TWI863912B - Machinability improvement film, laminated machinability improvement film and method of using machinability improvement film - Google Patents

Abstract

Provided is a machinability improvement film and the like which acquire an excellent cutting ability and an excellent durability by bonding a resin plate, a functional film and the like via a machinability improvement layer. A machinability improvement film and the like, comprises an active energy lay-curable machinability improvement layer for bonding to a resin plate, which is formed by laminating on a predetermined substrate, wherein, in a machinability improvement layer in state of being bonded to the resin plate, a storage modulus(M2) after irradiation of an active energy lay is a value of 0.2 MPa or more and an adhesion(P2) after irradiation of an active energy lay is a value of 10 N/25mm or more.

Description

Machinability-enhancing film, laminate, and method of using the machinability-enhancing film

The present invention relates to a film for improving machinability, a laminate (resin sheet with a film for improving machinability attached thereto), and a method for using the film for improving machinability. In particular, the present invention relates to a film for improving machinability, a laminate, and a method for using the film for improving machinability with excellent cutting properties and durability used in manufacturing touch panels or liquid crystal display devices.

In the past, a touch panel has been proposed for the purpose of suppressing the occurrence of interference fringes caused by light interference and for easily replacing a decorative film (for example, see Patent Document 1). More specifically, it is a touch panel device, which is characterized by having an operating area that accepts touch input and a non-operating area that does not accept touch input, and a concave-convex surface is formed on the bottom of the decorative film corresponding to the operating area.

In addition, there is proposed an adhesive sheet suitable for bonding a pair of optical components having concave and convex surfaces to each other in a touch panel or a liquid crystal display device (for example, refer to patent document 2). More specifically, it is an adhesive sheet having an adhesive layer (X) of an adhesive that is semi-hardened by heating an adhesive composition containing a base polymer (A), a monomer (B) having at least one polymerizable unsaturated group, a thermal crosslinking agent (C), a polymerization initiator (D) and a solvent (E).

Furthermore, it is proposed that during the punching process, the adhesive is not easy to seep out, and the adhesive seepage and adhesion on the cross-section is small, and it is not easy to produce paste contamination or paste defects during handling (for example, refer to patent document 3). More specifically, during the punching process, the area of the adhesive on the cross-section other than the adhesive is less than 20% of the area of the adhesive layer. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Application No. 2018-5698 (patent application scope, etc.) [Patent Document 2] WO2013-61938 (patent application scope, etc.) [Patent Document 3] Japanese Patent Application No. 2001-235626 (patent application scope, etc.)

[Problems to be solved by the invention]

However, the touch panel device disclosed in Patent Document 1 has a specific exterior unit (sheet metal/adhesive layer/decorative film), and these exterior units are manufactured by processing the sheet metal and the adhesive layer into specific shapes and then laminating them. Therefore, there are many manufacturing steps to obtain the exterior unit. In addition, the adhesive layer is designed to easily replace the decorative film, and there is no consideration about the adhesion. Therefore, when it is subjected to durable conditions (such as 85°C, 85%RH, 500 hours, etc.), the adhesive layer is peeled off from the decorative film due to bulging or peeling at the adhesive interface, and the problem of lack of durability is also seen.

Furthermore, the adhesive sheet disclosed in Patent Document 2 only considers the bonding of a pair of optical components having concave and convex surfaces, and does not consider the sandwiching of the adhesive sheet between the optical components and cutting into a specific shape. Therefore, since the storage elastic modulus value of the adhesive layer is not considered at all, the problem of the adhesive sheet's lack of cutting performance is also seen.

Furthermore, the optical component disclosed in Patent Document 3 specifically does not describe a method for controlling the adhesive area of the cross-section other than the adhesive to be less than 20% of the adhesive layer area during the punching process, which shows a problem of lack of practicality.

Therefore, the inventors of the present invention have made active efforts in view of the above situation and found that by setting the storage elastic modulus (M2) of the machinability enhancing layer of the machinability enhancing layer attached to the resin board and having the machinability enhancing layer laminated on the specific substrate with active energy ray curing properties to a specific value or above, even when a cutting device is used to cut the functional film and the machinability enhancing layer of one of the specific substrates in the state of the resin board, the occurrence of defects or elongation of the machinability enhancing layer during cutting can be suppressed, and the cutting surface after processing has excellent machinability (machinability). Furthermore, it was found that by setting the adhesion (P2) of the machinability enhancement layer after irradiation with active energy rays to a specific value or more, even when a functional film or the like of one of the specific substrates and the machinability enhancement layer are subjected to severe durability conditions (e.g., 85°C, 85%RH, 500 hours of hot and humid environment conditions) in a state including a resin sheet, the occurrence of bulges or peeling can be suppressed, and excellent durability can be exhibited. That is, the inventors of the present invention found that the above-mentioned machinability problem can be solved and the durability problem can also be solved, thereby completing the present invention. Therefore, the purpose of the present invention is to provide a film for improving machinability that has excellent machining properties (machinability) when machining (cutting) with a resin plate of a touch panel or liquid crystal display device and a specific substrate, and excellent durability when subjected to durable conditions, a laminate formed by attaching such a film for improving machinability to a resin plate, and an effective method for using such a film for improving machinability. [Means for solving the problem]

According to the present invention, a machinability-enhancing film is provided, which is characterized by being attached to a resin board and having an active energy ray-curable machinability-enhancing layer formed by laminating on a specific substrate. For the machinability-enhancing layer attached to the resin board, the storage elastic modulus (M2) after active energy ray irradiation is a value of 0.2MPa or more, and the adhesive force (P2) after active energy ray irradiation is a value of 10N/25mm or more, which can solve the above-mentioned problem. That is, by configuring the machinability enhancing film in this way, by setting the storage elastic modulus (M2) of the machinability enhancing layer after being irradiated with active energy rays in the state of being attached to the resin board to a specific value or more, when the machinability enhancing film is cut while including the resin board, the occurrence of defects or elongation of the machinability enhancing layer during cutting can be suppressed, and the cutting surface after processing has excellent cutting properties. In addition, by setting the adhesion (P2) of the machinability enhancing layer after being irradiated with active energy rays to a specific value or more, even in the state of the machinability enhancing layer attached to the resin board, no bubbles or bulges or peeling occur during the time-humidity durability test (e.g., 85°C, 85%RH, 500 hours, etc.), and excellent durability can be exerted.

Furthermore, when the machinability-enhancing film of the present invention is constituted, it is preferable to include a functional film or a release film as a specific substrate. By including a functional film or a release film in this way, the machinability-enhancing film can be handled well and the adhesion with the resin sheet can be improved. Thereby, the appearance of the laminated body due to bonding errors can be suppressed, and the durability reduction caused by air entrapment at the laminate interface can be prevented. Furthermore, as a specific substrate, it is also preferable to include both a functional film and a release film.

Furthermore, when the machinability-enhancing film of the present invention is constructed, the gel fraction (G2) of the machinability-enhancing layer after active energy ray irradiation is preferably 60% or more. By controlling the gel fraction (G2) of the machinability-enhancing layer in this way, better cutting properties can be obtained. In addition, since the cohesion of the machinability-enhancing layer after active energy ray irradiation becomes appropriate, it also helps to improve durability.

Furthermore, when the machinability enhancing film of the present invention is constructed, the storage elastic modulus (M1) of the machinability enhancing layer before active energy ray irradiation is preferably within the range of 0.01 to 1 MPa. By controlling the storage elastic modulus (M1) of the machinability enhancing layer before active energy ray irradiation in this way, the film has excellent adhesion to the resin sheet, and the durability reduction caused by air entrapment during bonding can be prevented.

Furthermore, when the machinability-enhancing film of the present invention is constructed, the storage elastic modulus (M2) of the machinability-enhancing layer after active energy ray irradiation is preferably within the range of 0.2 to 3 MPa. By controlling the storage elastic modulus (M2) of the machinability-enhancing layer after active energy ray irradiation in this way, the machinability-enhancing layer becomes one with appropriate cohesion, so in addition to exhibiting good machinability, it becomes one that is easy to have durability.

Furthermore, when constructing the machinability-enhancing film of the present invention, it is preferred to set the storage elastic modulus of the machinability-enhancing layer before active energy ray irradiation to M1, and the storage elastic modulus of the machinability-enhancing layer after active energy ray irradiation to M2, so that the value represented by M2/M1×100 (storage elastic modulus increase rate) is within the range of 320 to 30000%. By controlling the increase rate (%) of the storage elastic modulus within a specific range, it is easy to achieve both good adhesion of the machinability-enhancing layer before curing and moderate cohesion after curing, thereby obtaining good machinability and durability. Furthermore, when the bonding is good before curing, the adhesion at the bonding interface is also improved after curing, so that the defect or elongation of the machinability-enhancing layer during cutting can be easily controlled in combination with the effect.

Furthermore, when the machinability-enhancing film of the present invention is constructed, it is preferable to make the thickness of the machinability-enhancing layer a value within the range of 3 to 40 μm. By controlling the thickness of the machinability-enhancing layer of the machinability-enhancing film in this way, it is easy to adjust the 180° peeling adhesion to glass measured in accordance with JIS Z 0237:2000 before and after active energy ray irradiation (hereinafter sometimes referred to as adhesion) to a value within the desired range, thereby achieving good durability. In addition, since it is a relatively thin thickness, it is easy to contribute to the weight reduction of the obtained laminate.

In addition, another aspect of the present invention is a laminate, which is characterized by attaching any of the above-mentioned machinability-enhancing films to a resin plate. According to such laminates, since resin plates have better machinability than conventional metal frames, various functional films used in various machines can be cut with good precision by attaching the machinability-enhancing layer to the resin plate. In addition, since resin plates are lighter than conventional metal frames, the machine using the laminate can also be made lighter.

Furthermore, when constituting the laminate of the present invention, the resin sheet is preferably an optical resin sheet. Laminated bodies including such optical resin sheets can be easily applied to optical devices, such as optical parts of touch panels or liquid crystal display devices, and have optical properties and can also be lightweight.

In addition, another aspect of the present invention is a method for using any of the above-mentioned machinability-enhancing films, which is characterized by comprising the following steps (1) to (4): (1) coating a composition containing an active energy ray-hardening component on the surface of a functional film as a specific substrate, and preparing a machinability-enhancing film having a machinability-enhancing layer with active energy ray hardening properties by heat treatment, (2) attaching the obtained machinability-enhancing film to a resin board, (3) irradiating active energy rays from the resin board or the specific substrate side to harden the active energy ray-hardening component in the machinability-enhancing layer to prepare a hardened machinability-enhancing layer, (4) performing a specific machining treatment on a laminate comprising the hardened machinability-enhancing layer and the resin board. By using such machinability-enhanced films, it is possible to apply them to optical parts such as touch panels or liquid crystal display devices, and resin plates with functional films attached through the machinability-enhanced layer can be easily manufactured. That is, a laminate having a desired shape can be easily obtained through a single cutting process. Furthermore, since there is no damage or elongation of the machinability-enhanced layer during the cutting process, the cutting surface after processing is good, and the obtained laminate has excellent appearance quality. Furthermore, since the obtained laminate has excellent durability, it can also be applied to optical parts used in harsh environments (such as automotive touch panels or liquid crystal display devices, etc.).

The embodiment of the present invention, as shown in FIG. 1(a) to (b), is a machinability enhancement film 18 formed by a machinability enhancement layer 14 having active energy ray curability and a specific substrate 16 (functional film) attached to a resin plate 12, or a laminate formed using such a machinability enhancement film 18, and further a method of using the machinability enhancement film 18. Therefore, the machinability enhancement film 18 of the present embodiment is characterized in that the storage elastic modulus (M2) of the machinability enhancement layer 14 laminated on the resin plate 12 after active energy ray irradiation is 0.2 MPa or more, and the adhesive force (P2) after active energy ray irradiation is 10 N/25 mm or more. The following will specifically describe the machinability-enhancing film 18 for each component with reference to appropriate figures. In addition, FIG. 1(a) is an example of a laminate 10 composed of a resin sheet 12 on which the machinability-enhancing film 18 is laminated, and FIG. 1(b) is an example of another laminate 10, which is an example of a touch panel having a specific space 14a in a portion of the machinability-enhancing layer 14 (but electrical wiring, etc. are omitted).

1. Resin board (1) Type The type of the resin board 12 shown in FIG. 1(a) is not particularly limited, but a known transparent or translucent resin board can be preferably used because of its good machinability.

Examples of such resin sheets include polyester resin sheets such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene resin sheets, polypropylene resin sheets, diacetyl cellulose resin sheets, triacetyl cellulose resin sheets, acetyl cellulose butyral resin sheets, polyvinyl chloride resin sheets, polyvinylidene chloride resin sheets, polyvinyl alcohol resin sheets, and polyvinyl alcohol resin sheets. Resin board, ethylene-vinyl acetate copolymer resin board, polystyrene resin board, polycarbonate resin board, polymethylpentene resin board, polysulfone resin board, polyetheretherketone resin board, polyethersulfone resin board, polyetherimide resin board, polyimide resin board, fluororesin board, polyamide resin board, acrylic resin board, norbornene series resin board, cycloolefin resin board, etc.

Among them, at least one of polyester resin sheet, polycarbonate resin sheet, polymethylpentene resin sheet, polyester resin sheet, acrylic resin sheet, polyetheretherketone resin sheet, polyimide resin sheet, norbornene resin sheet, and cycloolefin resin sheet is preferred due to good optical properties or heat resistance and excellent dimensional stability. Moreover, acrylic resin sheet (MMA resin sheet, etc.) or polycarbonate resin sheet is particularly preferred due to excellent transparency or mechanical strength, flexibility, processability, weather resistance, and economical performance.

(2) Thickness The thickness of the resin sheet 12 shown in FIG. 1(a) is usually preferably within the range of 200 to 10,000 μm. The reason is that if the thickness of the resin sheet is less than 200 μm, the strength of the resin sheet is reduced, and the fixity of the configuration of the touch panel, etc., including the resin sheet, is reduced. On the other hand, if the thickness of the resin sheet exceeds 10,000 μm, it is difficult to perform mechanical processing on the resin sheet and the functional film, etc., which is a specific substrate, through the machinability enhancement layer. Therefore, the thickness of the resin sheet is preferably within the range of 500 to 5,000 μm, and more preferably within the range of 700 to 2,000 μm.

(3) Optical properties Regarding the optical properties of the resin sheet, it is preferred that the sheet have a degree of transparency that allows it to be used in applications such as touch panels or liquid crystal display devices. Specifically, if the visible light transmittance of the resin sheet is too low, the yield rate will be significantly reduced, and the types of constituent materials that can be used may be excessively limited. Therefore, the lower limit of the visible light transmittance of the resin sheet is preferably set to a value of 60% or more, more preferably a value of 75% or more, and more preferably a value of 85% or more. On the other hand, the upper limit of the visible light transmittance of the resin sheet is usually 100% or less, preferably 99.9% or less, more preferably 99% or less, and more preferably 98% or less.

(4) Additives In order to improve the durability, physical properties, mechanical properties, etc., it is also better to mix at least one known additive such as antioxidant, hydrolysis inhibitor, ultraviolet absorber, inorganic filler, organic filler, inorganic fiber, organic fiber, conductive material, electrical insulating material, metal ion scavenger, lightweight agent, filler, abrasive, colorant, viscosity adjuster, etc. into the resin board. Therefore, when these known additives are mixed in the resin board, the mixing amount depends on the type of additive, but is usually preferably set to a value in the range of 0.1 to 30 weight %, more preferably 0.5 to 20 weight %, and even more preferably 1 to 10 weight %, relative to the total amount of the resin board (100 weight %).

2. Machinability-enhancing layer The machinability-enhancing layer 14 of the present embodiment can be obtained by heat-treating the resin layer 13 derived from the composition for forming the machinability-enhancing layer to perform thermal crosslinking, wherein the composition has a (meth)acrylate copolymer as a main agent (A), a thermosetting component (B), and an active energy ray-curing component (C) as essential components. That is, the machinability-enhancing layer 14 is composed of a (meth)acrylate copolymer as a main agent (A), a crosslinked structure composed of the thermosetting component (B), and an uncured active energy ray-curing component (C). The machinability-enhancing layer 14 is cured by irradiating the machinability-enhancing layer 14 with active energy rays to obtain a cured machinability-enhancing layer 14'.

In addition, in this specification, "(meth)acrylate" means both acrylate and methacrylate, and the same applies to other similar terms included below. Below, each component constituting the machinability enhancement layer 14 is specifically described.

(1) Main agent (A) The type of the main agent (A) constituting the machinability-enhancing layer 14 is not particularly limited. However, for example, based on the ease of obtaining and the ease of uniform mixing with the active energy ray-curable component (C) described later, it is preferred to use a (meth)acrylate copolymer derived from a specific (meth)acrylate monomer component as the main agent (A).

When the main agent is a (meth)acrylate copolymer, it is preferable that the monomer units constituting the copolymer contain a monomer having a reactive group in the molecule (a monomer containing a reactive functional group) that reacts with the thermosetting component (B) and an alkyl (meth)acrylate. The reason is that the reactive group of the monomer containing a reactive group reacts with the thermosetting component (B) to form a cross-linked structure (three-dimensional mesh structure), thereby obtaining a mechanical processing improvement layer with relatively high film strength.

(1)-1 Monomer 1 (monomer containing reactive functional groups) The monomer containing reactive groups that constitutes a part of the (meth)acrylate polymer as the main agent (A) may be, for example, a monomer having a hydroxyl group in the molecule (hereinafter sometimes referred to as a hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (hereinafter sometimes referred to as a carboxyl group-containing monomer), a monomer having an amino group in the molecule (hereinafter sometimes referred to as an amino group-containing monomer), etc. Among these, monomers containing hydroxyl groups are preferred from the viewpoint of excellent reactivity with the thermosetting component (B) and less adverse effects on the adherend, and even if the weight average molecular weight of the (meth)acrylate copolymer is relatively low, monomers containing carboxyl groups are preferred from the viewpoint of exerting the desired cohesive force.

Examples of monomers containing a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among them, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and 4-hydroxybutyl acrylate are more preferred, based on the reactivity of the hydroxyl group in the obtained (meth)acrylate copolymer with the thermosetting component (B) and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

Furthermore, the amount of the hydroxyl-containing monomer as a monomer unit is preferably 1% by weight or more, more preferably 10% by weight or more, and more preferably 15% by weight or more relative to the total amount of the monomer (100% by weight, the same below). Furthermore, the amount of the hydroxyl-containing monomer is preferably 50% by weight or less, more preferably 40% by weight or less, and more preferably 30% by weight or less relative to the total amount of the monomer. That is, the (meth)acrylate copolymer reacts more easily with the thermosetting component (B) to form a good crosslinking structure by containing a hydroxyl-containing monomer as a monomer component in a specific range. As a result, the film strength of the obtained machinability-enhancing layer is relatively high, and the storage elastic modulus of the machinability-enhancing layer easily meets the expected value, thereby becoming a layer with good cutting properties.

Examples of carboxyl-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, furoic acid, etc. Among them, acrylic acid is preferred from the viewpoint of the reactivity of the carboxyl group in the obtained (meth)acrylate copolymer with the thermosetting component (B) and the copolymerizability with other monomers. These can be used alone or in combination of two or more. Moreover, when the carboxyl-containing monomer is included as a monomer unit, the (meth)acrylate copolymer preferably contains 1% by weight or more, particularly preferably 5% by weight or more, and more preferably 8% by weight or more relative to the total amount of the monomer. Furthermore, the (meth)acrylate copolymer preferably contains 30% by weight or less of the carboxyl-containing monomer as a monomer unit constituting the polymer, more preferably 20% by weight or less, and even more preferably 15% by weight or less. That is, by containing carboxyl-containing monomers as monomer units within a specific range, it reacts more easily with the thermosetting component (B) to form a good cross-linking structure. As a result, the film strength of the obtained machinability-enhancing layer is relatively high, and the storage elastic modulus of the machinability-enhancing layer is easy to meet the expected value, and it becomes a layer with good machinability.

In addition, as a monomer unit, it is better to include a trace amount of carboxyl-containing monomers or not include them at all. The reason is that since carboxyl groups are acid components, by not including carboxyl-containing monomers, when there are defects caused by acid in the adhesive attachment object, such as transparent conductive films such as tin-doped indium oxide (ITO) or metal films, such defects caused by acid (corrosion, resistance value change, etc.) can be suppressed. However, it is also allowed to contain a specific amount of carboxyl-containing monomers to the extent that such defects will not be generated. Specifically, in the (meth)acrylate copolymer, as a monomer unit, it is allowed to contain carboxyl-containing monomers in an amount of 5% by weight or less, preferably 1% by weight or less, and more preferably 0.1% by weight or less.

In addition, examples of monomers containing an amino group include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These monomers can be used alone or in combination of two or more.

(1)-2 Monomer 2 ((meth)acrylate alkyl ester monomer) The (meth)acrylate copolymer as the main agent (A) preferably contains a (meth)acrylate alkyl ester having an alkyl group with a carbon number of 1 to 20 as a monomer unit constituting the copolymer. Thereby, the machinability-enhancing layer can exhibit better adhesion. In addition, from the viewpoint of exhibiting better adhesion, the (meth)acrylate alkyl ester having a carbon number of 1 to 20 is preferably a straight chain or branched chain structure.

The (meth) alkyl acrylate having a carbon number of 1 to 20 preferably has a glass transition temperature (Tg) of less than 0°C as a homopolymer (hereinafter sometimes referred to as a low-Tg alkyl acrylate). The reason is that by containing the low-Tg alkyl acrylate as a constituent monomer unit, the adhesion of the obtained machinability-enhancing layer can be further improved.

Here, as the low Tg alkyl acrylate, at least one of n-butyl acrylate (Tg: -55°C), n-octyl acrylate (Tg: -65°C), isooctyl acrylate (Tg: -58°C), 2-ethylhexyl acrylate (Tg: -70°C), isononyl acrylate (Tg: -58°C), isodecyl acrylate (Tg: -60°C), isodecyl methacrylate (Tg: -41°C), n-lauryl methacrylate (Tg: -65°C), tridecyl acrylate (Tg: -55°C), tridecyl methacrylate (Tg: -40°C) and the like can be preferably cited. Among them, from the viewpoint of more effectively improving adhesion, the low Tg alkyl acrylate is preferably a homopolymer having a Tg of -25°C or less, and more preferably a homopolymer having a Tg of -50°C or less. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred.

In addition, the (meth)acrylate copolymer preferably contains 30% by weight or more, particularly preferably 40% by weight or more, and more preferably 50% by weight or more of low Tg alkyl acrylate as a monomer unit constituting the polymer as a lower limit. The reason is that if the low Tg alkyl acrylate is formulated in this way, the adhesion of the obtained machinability-enhancing layer can be improved, and the adhesion to the resin board can be better. In addition, the (meth)acrylate copolymer preferably contains 99% by weight or less, particularly preferably 90% by weight or less, and more preferably 80% by weight or less of low Tg alkyl acrylate as a monomer unit constituting the polymer as an upper limit. The reason is that if the low Tg alkyl acrylate is formulated in this way, an appropriate amount of other monomer components (especially monomers containing reactive functional groups) can be introduced into the (meth)acrylate polymer.

In addition, (meth)acrylate polymers are also preferably used in combination with monomers having a glass transition temperature (Tg) of more than 0°C as homopolymers (hereinafter sometimes referred to as high-Tg alkyl acrylates) as monomer units. The reason is that appropriate cohesion can be imparted to the obtained machinability-enhancing layer, the storage elastic modulus of the machinability-enhancing layer can easily meet the expected value, and the machinability can be improved.

However, the high Tg alkyl acrylates described in this article exclude the monomers with alicyclic structures and nitrogen-containing monomers described later. As such high Tg alkyl acrylates, preferably, at least one of methyl acrylate (Tg: 10°C), methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-butyl methacrylate (Tg: 20°C), isobutyl methacrylate (Tg: 48°C), tert-butyl methacrylate (Tg: 107°C), n-stearyl acrylate (Tg: 30°C), n-stearyl methacrylate (Tg: 38°C), vinyl acetate (Tg: 32°C), styrene (Tg: 30°C), etc. can be cited. Among these, methyl methacrylate is particularly preferred as the high Tg alkyl acrylate from the viewpoint of providing a suitable cohesive force to the machinability-enhancing layer and exhibiting a desired storage elastic modulus.

That is, when the (meth)acrylate polymer contains the above-mentioned high Tg alkyl acrylate as a monomer unit constituting the polymer, the high Tg alkyl acrylate is preferably contained in an amount of 1% by weight or more, and more preferably in an amount of 3% by weight or more, relative to the total amount of the monomer component. Moreover, the (meth)acrylate polymer preferably contains 20% by weight or less, more preferably 12% by weight or less, and more preferably 8% by weight or less of the high Tg alkyl acrylate as a monomer unit constituting the polymer. The reason is that by using the high Tg alkyl acrylate and the low Tg alkyl acrylate together in the above-mentioned amount, the obtained machinability-enhancing layer can exhibit appropriate adhesion and cohesion, and the adhesion and storage elastic modulus are easy to meet the expected values, and it is easy to exert cutting properties and durability.

(1)-3 Monomer 3 (monomer containing alicyclic structure) The (meth)acrylate copolymer as the main agent (A) preferably contains a monomer having an alicyclic structure in the molecule (monomer containing alicyclic structure) as a monomer unit constituting the polymer. The reason is that the monomer molecule containing alicyclic structure is structurally large, so by having it exist in the copolymer, it is presumed that the interval between polymers can be expanded. As a result, the obtained machinability-enhanced layer can be excellent in flexibility. Therefore, by making the (meth)acrylate copolymer contain a monomer containing alicyclic structure as a monomer unit constituting the polymer, the composition can be crosslinked, and the obtained machinability-enhanced layer can be excellent in adhesion to the resin board.

In addition, the carbon ring of the alicyclic structure in the monomer containing the alicyclic structure may be a saturated structure or may have unsaturated bonds in part. And these alicyclic structures may be monocyclic alicyclic structures or polycyclic alicyclic structures such as bicyclic and tricyclic. Based on the viewpoint of expanding the interval between polymers in the obtained (meth)acrylate copolymer and effectively exerting the flexibility of the machinability-enhancing layer, the above-mentioned alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure). Furthermore, based on the good compatibility between the (meth)acrylate copolymer and other components, the above-mentioned polycyclic structure is particularly preferably bicyclic to tetracyclic.

Moreover, similarly to the above, from the viewpoint of effectively exerting the softness of the adhesive, the carbon number of the alicyclic structure (meaning the total carbon number of the part forming the ring, and when multiple rings exist independently, it means the total carbon number) is usually preferably 5 or more, and more preferably 7 or more. On the other hand, the upper limit of the carbon number of the alicyclic structure is not particularly limited, but similarly to the above, from the viewpoint of compatibility, it is preferably 15 or less, and more preferably 10 or less.

Therefore, as the alicyclic structure contained in the monomer containing an alicyclic structure, examples include at least one of a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, an isobornyl skeleton, a cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.), a cycloene skeleton (cycloheptene skeleton, cyclooctene skeleton), a norbornene skeleton, a norbornadiene skeleton, a cubane skeleton, a basketane skeleton, a housane skeleton, a spiro skeleton, etc.

Moreover, among them, from the viewpoint of obtaining better durability, it is preferred to contain a dicyclopentadiene skeleton (alicyclic carbon number: 10), an adamantane skeleton (alicyclic carbon number: 10) or an isobornyl skeleton (alicyclic carbon number: 7), and it is more preferred to contain an isobornyl skeleton. Therefore, as the above-mentioned monomer containing an alicyclic structure, it is preferred to be a (meth)acrylate monomer containing the above-mentioned skeleton. Specifically, it is exemplified by at least one of cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantane (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc. Among them, from the viewpoint of obtaining better durability, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate or isobornyl (meth)acrylate is preferred, isobornyl (meth)acrylate is more preferred, and isobornyl acrylate is particularly preferred.

In addition, the (meth)acrylate copolymer preferably contains 1% by weight or more, more preferably 4% by weight or more, and more preferably 8% by weight or more of monomers containing a lipid ring structure as monomer units constituting the copolymer relative to the total amount of monomers. Similarly, the (meth)acrylate copolymer preferably contains 40% by weight or less, more preferably 30% by weight or less, and more preferably 24% by weight or less of monomers containing a lipid ring structure as monomer units constituting the copolymer, and in terms of achieving better durability, it is particularly preferred to contain 18% by weight or less. By making the content of the monomer containing a lipid ring structure within the above range, the resulting machinability-enhancing layer has better flexibility, better adhesion to the resin board, and is more likely to meet the desired adhesion value, and easy to exert cutting properties and durability.

(1)-4 Monomer 4 (nitrogen-containing monomer) The (meth)acrylate copolymer as the main agent (A) preferably contains a monomer having a nitrogen atom in the molecule (nitrogen-containing monomer) as a monomer unit constituting the polymer. In addition, the amine-containing monomer exemplified as a monomer containing a reactive functional group is excluded from the nitrogen-containing monomer. By the presence of a nitrogen-containing monomer as a constituent unit in the copolymer, the reactivity of the acrylate copolymer and the thermosetting component (B) can be promoted, polarity can be imparted to the machinability-enhancing layer, and the cohesion of the machinability-enhancing layer can be improved.

Examples of the above-mentioned nitrogen-containing monomers include monomers having tertiary amine groups, monomers having amide groups, and nitrogen-containing heterocyclic monomers. Among them, monomers having nitrogen-containing heterocyclic monomers are preferred. Examples of the monomers having nitrogen-containing heterocyclic monomers include at least one of N-(methyl)acryloyl morpholine, N-vinyl-2-pyrrolidone, N-(methyl)acryloyl pyrrolidone, N-(methyl)acryloyl piperidine, N-(methyl)acryloyl pyrrolidine, N-(methyl)acryloyl aziridine, (methyl)acrylic acid aziridine ethyl ester, 2-vinyl pyridine, 4-vinyl pyridine, 2-vinyl pyrazine, 1-vinylimidazole, N-vinyl carbazole, and N-vinyl phthalimide. Among them, N-(meth)acryloylmorpholine is preferred, and N-acryloylmorpholine is more preferred, from the viewpoint of obtaining a better adhesive force.

In addition, as a nitrogen-containing monomer other than the above-mentioned monomer having a nitrogen-containing heterocyclic ring, there can be exemplified at least one of (meth)acrylamide, N-methyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-ethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-phenyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, N-vinylcaprolactam, dimethylaminoethyl(meth)acrylate, and the like.

Moreover, the (meth)acrylate copolymer preferably contains 1% by weight or more, more preferably 2% by weight or more, and more preferably 4% by weight or more of nitrogen-containing monomers relative to the total monomer components. Moreover, the (meth)acrylate copolymer preferably contains 40% by weight or less, more preferably 30% by weight or less, and more preferably 20% by weight or less of nitrogen-containing monomers as monomer units constituting the copolymer, and preferably contains 10% by weight or less in order to achieve better durability. This is because by making the content of nitrogen-containing monomers fall within the above range, the cohesive force of the obtained machinability-enhancing layer is effectively improved, and it is easy to meet the desired storage elastic modulus value, which can achieve better durability.

(1)-5 Monomer 5 (other monomers) The (meth)acrylate copolymer as the main agent (A) preferably contains other monomers different from the above-mentioned monomer components as monomer units constituting the polymer as needed. Such other monomers are preferably monomers that do not contain reactive functional groups. That is, examples include (meth)acrylate alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, styrene, etc. These monomers may be used alone or in combination of two or more. In addition, the polymerization state of the (meth)acrylate copolymer may be a random copolymer or a block copolymer.

(1)-6 Weight average molecular weight When the main agent (A) constituting the machinability-enhancing layer 14 is a (meth)acrylate copolymer, its weight average molecular weight (Mw) is preferably set to a value in the range of 50,000 to 2.5 million. The reason is that when the weight average molecular weight of the (meth)acrylate copolymer is set to a value below 50,000, the cohesive force is reduced, the copolymer peels off from the resin sheet, and the adhesion is significantly reduced. On the other hand, when the weight average molecular weight of the (meth)acrylate copolymer is set to a value exceeding 2.5 million, the handling becomes difficult, and the adhesion to the resin sheet is reduced. Therefore, the weight average molecular weight of the (meth)acrylate copolymer is preferably set to a value in the range of 100,000 to 1.8 million, particularly preferably set to a value in the range of 200,000 to 1.2 million, and more preferably set to a value in the range of 300,000 to 800,000. The weight average molecular weight of the main agent of the machinability improving layer can be determined by comparing it with a pre-prepared calibration curve for standard polystyrene particles using GPC (gel permeation chromatography).

(1)-7 Polymerization of (meth)acrylate copolymer The (meth)acrylate copolymer as the main agent (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional free radical polymerization method. The polymerization of the (meth)acrylate copolymer can be carried out by a solution polymerization method or the like using a polymerization initiator. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc., and two or more kinds may be used in combination.

Examples of polymerization initiators for the polymerization of (meth)acrylate copolymers include azo compounds, organic peroxides, etc., and two or more types may be used in combination. More specifically, examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexyl-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(2-methylpropionic acid)dimethyl ester, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumyl hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxyvalerate, (3,5,5-trimethylhexyl) peroxide, dipropionyl peroxide, diacetyl peroxide, etc. In addition, in the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted to a desired value by mixing a chain transfer agent such as 2-hydroxyethanol.

(2) Thermosetting component (B) When a composition containing a thermosetting component (B) is heated, the thermosetting component (B) undergoes a crosslinking reaction with the (meth)acrylate copolymer as the main agent (A) to form a crosslinked structure (three-dimensional mesh structure). This allows a layer with improved machinability and relatively high mold strength to be obtained. The type of such thermosetting component (B) may be any one that reacts with the main agent (A) (e.g., a (meth)acrylate copolymer), and preferably any one that reacts with a reactive group (e.g., a hydroxyl group or a carboxyl group, etc.) introduced into the main agent (A) of the composition. Therefore, the thermosetting component (B) is exemplified by at least one of an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent, a melamine crosslinking agent, an aziridine crosslinking agent, a diamine crosslinking agent, an aldehyde crosslinking agent, an oxazoline crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate crosslinking agent, a metal salt crosslinking agent, an ammonium salt crosslinking agent, etc. The type of the thermosetting component (B) can be selected according to the reactivity of the reactive group possessed by the main agent (A). For example, when the reactive group possessed by the main agent (A) is a hydroxyl group, it is better to prepare an isocyanate crosslinking agent having excellent reactivity with the hydroxyl group. Furthermore, when the reactive group of the main agent (A) is a carboxyl group, it is better to use an epoxy-based crosslinking agent that has excellent reactivity with the carboxyl group. Moreover, the thermosetting component (B) can be used alone or in combination of two or more.

In addition, the isocyanate crosslinking agent preferably contains at least a polyisocyanate compound. Here, examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and urea bodies and isocyanurate bodies thereof, and adducts of reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trihydroxymethylpropane, and castor oil. Among them, trihydroxymethylpropane-modified aromatic polyisocyanates are preferred from the viewpoint of reactivity with hydroxyl groups, and at least one of trihydroxymethylpropane-modified toluene diisocyanate and trihydroxymethylpropane-modified xylene diisocyanate is particularly preferred.

In addition, examples of epoxy crosslinking agents include at least one of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxymethylpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine. Among them, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is particularly preferred from the viewpoint of reactivity with carboxyl groups.

Furthermore, the amount of the thermosetting component (B) is preferably set to a value within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the main agent (A). The reason is that when the amount of the thermosetting component (B) is set to a value less than 0.05 parts by weight, the reactivity with the hydroxyl group or carboxyl group introduced into the main agent is significantly reduced, and the resulting machinability-enhancing layer cannot obtain the desired cohesive force and cannot exert specific adhesiveness. As a result, there is a case where the machinability-enhancing layer is peeled off from the resin sheet and the adhesion is significantly reduced. On the other hand, when the amount of the thermosetting component (B) is set to a value exceeding 10 parts by weight, the thermosetting component (B) reacts excessively with the hydroxyl group or carboxyl group introduced into the main agent (A), and the cohesive force of the machinability-enhancing layer becomes too high, and the adhesion is significantly reduced. Therefore, the amount of the thermosetting component (B) is preferably set to a value within the range of 0.1 to 5 parts by weight, and more preferably within the range of 0.3 to 1 part by weight, relative to 100 parts by weight of the main agent (A).

(3) Active energy ray-hardening component (C) The machinability-enhancing layer of this embodiment preferably contains an active energy ray-hardening component (C). After the machinability-enhancing layer is attached to the adherend (resin sheet), when the active energy ray is irradiated, the polymerization of the active energy ray-hardening component (C) is promoted starting from the cracking of the photopolymerization initiator (D) described later. The polymerized active energy ray-hardening component (C) is presumed to be entangled in the crosslinked structure (three-dimensional mesh structure) formed by the thermal crosslinking of the main agent (A) and the thermosetting component (B). Therefore, the machinability-enhancing layer having such a high-dimensional structure can easily meet the desired adhesion value, and has excellent durability under high temperature and high humidity conditions, and can also easily meet the desired storage elastic modulus value, and has excellent machinability.

Here, the active energy ray-curable component (C) is not particularly limited as long as it is a component that produces a curing reaction by irradiating active energy rays to obtain the above-mentioned effect. In addition, the active energy ray-curable component (C) may be any of a monomer, an oligomer or a polymer, or a mixture thereof. Among them, a multifunctional acrylate monomer having a weight average molecular weight of less than 1,000 and having excellent compatibility with the main agent (A) is preferred.

More specifically, as a multifunctional acrylate monomer having a weight average molecular weight of less than 1,000, it is preferably an acrylate monomer having 2 to 6 reactive functional groups. Here, examples of the acrylate monomer having two reactive functional groups include at least one of 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxyvaleric acid neopentyl glycol di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl) isocyanurate, allyl cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene.

In addition, examples of the acrylate monomer having three reactive functional groups include at least one of trihydroxymethylpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trihydroxymethylpropane tri(meth)acrylate, tris(acryloyloxyethyl)isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloyloxyethyl)isocyanurate.

Furthermore, examples of acrylate monomers having four reactive functional groups include diglycerol tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate. Examples of acrylate monomers having five reactive functional groups include at least one of propionic acid-modified dipentaerythritol penta(meth)acrylate. Examples of acrylate monomers having six reactive functional groups include at least one of dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

Among them, from the viewpoint of improving the durability of the machinability-enhancing layer, acrylate monomers having 3 to 6 reactive functional groups are particularly preferred. Specifically, trihydroxymethylpropane triacrylate, dipentaerythritol hexaacrylate, and ε-caprolactone-modified tri-(2-(methyl)acryloyloxyethyl) isocyanurate are particularly preferred.

In addition, it is also preferable to use an active energy ray-curable acrylate oligomer as the active energy ray-curable component (C). Examples of such acrylate oligomers include at least one of polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and polysilicone acrylate. Moreover, the weight average molecular weight of such acrylate oligomers is preferably 50,000 or less, more preferably 500 to 50,000, and even more preferably 3,000 to 40,000.

Furthermore, as the active energy ray-hardening component (C), it is also preferable to use an addition acrylate polymer having a (meth)acrylic group introduced into the side chain. Such addition acrylate polymers can be obtained by using a copolymer of (meth)acrylic acid ester and a monomer having a crosslinking functional group in the molecule, and reacting a part of the crosslinking functional group of the copolymer with a compound having a group that reacts with the (meth)acrylic group and the crosslinking functional group. The weight average molecular weight of the above-mentioned addition acrylate polymer is preferably about 50,000 to 900,000, and more preferably about 100,000 to 500,000.

In this embodiment, the active energy ray-hardening component (C) preferably uses the aforementioned multifunctional acrylate monomer, but one type may be selected from multifunctional acrylate monomers, acrylate oligomers and addition acrylate polymers, or two or more types may be used in combination, or these components may be used in combination with other active energy ray-hardening components.

Furthermore, the amount of the active energy ray curable component (C) is preferably set to a value within the range of 1 to 50 parts by weight relative to 100 parts by weight of the main agent (A). The reason is that when the amount of the active energy ray curable component (C) is set to a value less than 1 part by weight, it lacks reactivity and may not be able to obtain good mechanical processing properties. On the other hand, when the amount of the active energy ray curable component (C) is set to more than 50 parts by weight, the reactivity cannot be controlled, and it will react excessively with the main agent (A), making the cross-linked structure too dense, reducing the adhesion, and may not be able to obtain good durability. Therefore, the lower limit of the amount of the active energy ray curable component (C) is preferably set to 3 parts by weight or more, particularly preferably 6 parts by weight or more, and more preferably 10 parts by weight or more, relative to 100 parts by weight of the main agent (A). On the other hand, the upper limit of the amount of the active energy ray curable component (C) is preferably set to 30 parts by weight or less, particularly preferably 20 parts by weight or less, and more preferably 13 parts by weight or less.

(4) Photopolymerization initiator (D) Since the active energy ray-curable component (C) can be effectively cured by irradiation with active energy rays, it is preferable to contain a photopolymerization initiator (D) as desired.

Examples of the photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, benzophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl) At least one of benzophenone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthiazonone, 2-ethylthiazonone, 2-chlorothiazonone, 2,4-dimethylthiazonone, 2,4-diethylthiazonone, benzyl dimethyl acetal, acetophenone dimethyl acetal, p-dimethylaminobenzoate, 2,4,6-trimethylbenzyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide, and the like.

Among them, when ultraviolet rays are used as active energy rays, it is better to contain a photopolymerization initiator (D) having an absorption wavelength outside the ultraviolet absorption wavelength region, and it is more preferable to contain a photopolymerization initiator (D) having an absorption wavelength on the longer wavelength side (380nm or more) than the ultraviolet region, and it is particularly preferable to contain a photopolymerization initiator (D) having an absorption wavelength in the wavelength region of 380nm to 410nm. Specifically, it is better to contain 2,4,6-trimethylbenzyl-diphenylphosphine oxide or bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide. The reason is as follows. Since mobile electronic devices with touch panels are mostly used outdoors, their components may be degraded by ultraviolet rays. To solve this problem, there is a method of suppressing deterioration due to ultraviolet light by assembling a component having ultraviolet light absorption performance (ultraviolet light shielding component) in an electronic device. By assembling the ultraviolet light shielding component in the electronic device, when ultraviolet light is irradiated from the ultraviolet light shielding component side, if a photopolymerization initiator (D) that does not have an absorption wavelength outside the ultraviolet light absorption wavelength region is used in the machinability improvement layer, the ultraviolet light cannot be cured due to the shielding of the ultraviolet light shielding material component. On the other hand, in such a case, if a photopolymerization initiator (D) that has an absorption wavelength outside the ultraviolet light absorption wavelength region is used in the machinability improvement layer, the ultraviolet light can be fully cured by utilizing the wavelength outside the ultraviolet light absorption wavelength region.

The amount of the photopolymerization initiator (D) is preferably 0.5 to 25 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 5 to 15 parts by weight, based on 100 parts by weight of the active energy ray-curable component (C).

(5) Silane coupling agent (E) The composition used to form the machinability enhancing layer preferably further contains a silane coupling agent (E). Therefore, when the adherend includes a glass component or a resin component, the adhesion between the machinability enhancing layer and the adherend is improved. Therefore, the machinability enhancing layer containing a silane coupling agent (E) becomes more durable under high temperature and high humidity conditions.

Here, the type of silane coupling agent (E) is an organic silicon compound having at least one alkoxysilyl group in the molecule, preferably one having light transmittance. Examples of such silane coupling agents (E) include silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidyloxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; silicon compounds containing olefins such as 3-butylpropyltrimethoxysilane, 3-butylpropyltriethoxysilane, and 3-butylpropyldimethoxymethylsilane; silane compounds containing amino groups; silane compounds containing amino groups such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; condensates of 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These compounds may be used alone or in combination of two or more.

In addition, the amount of the silane coupling agent (E) is preferably set within the range of 0.01 to 5 parts by weight relative to 100 parts by weight of the main agent (A). The reason is that if the amount of the silane coupling agent (E) is set to a value less than 0.01 parts by weight, the effect of the compounding may not be easily obtained. On the other hand, if the amount of the silane coupling agent (E) is set to a value exceeding 5 parts by weight, the hydroxyl group or carboxyl group introduced into the main agent (A) may react excessively with the thermosetting component (B) due to the silane coupling agent (E), thereby significantly reducing the adhesion. Therefore, the amount of the silane coupling agent (E) is preferably set to a value within the range of 0.1 to 3 parts by weight, and more preferably set to a value within the range of 0.2 to 1 part by weight, relative to 100 parts by weight of the main agent (A).

(6) Additives In order to further improve the machinability or mechanical properties of the machinability enhancing layer, in addition to the above-mentioned silane coupling agent (E), it is also preferred to formulate at least one known additive such as inorganic filler, organic filler, inorganic fiber, organic fiber, conductive material, electrical insulating material, metal ion scavenger, lightweight agent, thickener, filler, abrasive, colorant, antioxidant, hydrolysis inhibitor, ultraviolet absorber, etc. Therefore, when these conventional additives are added, their amount is usually preferably set to a value within the range of 0.1 to 50 wt %, and more preferably set to a value within the range of 0.5 to 30 wt %, relative to the total amount (100 wt %) of the main agent (A).

(7) Thickness The thickness of the machinability enhancing layer is preferably set to a value within the range of 3 to 40 μm. The reason is that if the thickness of the machinability enhancing layer is set to a value less than 3 μm, the desired adhesion cannot be exhibited, and there is a tendency for the adhesion or durability to the resin board to deteriorate. On the other hand, if the thickness of the machinability enhancing layer is set to a value exceeding 40 μm, there is a possibility that the cutting performance deteriorates, or it is difficult to adjust the adhesion before and after the active energy ray irradiation to a value within the desired range. Therefore, the thickness of the machinability enhancing layer is preferably set to a value within the range of 8 to 30 μm, and more preferably set to a value within the range of 10 to 20 μm.

3. Specific substrate The type of specific substrate is not particularly limited, but it is typically a functional film or a release film.

When the specific substrate is a functional film, its type is, for example, at least one of a decorative film in a touch panel, a deflection film in a liquid crystal display device, a phase difference film, a light diffusion film, a light control film, an anti-glare film, a photocatalytic film, an ultraviolet shielding film, a heat-insulating film, an antistatic film, a conductive film, a semi-mirror film, a hard coating film, a decorative film, a holographic film, etc. The above-mentioned various functional films have functional layers on the surface or inside for imparting various functions (decoration, light polarization, light phase, light diffusion, light control, anti-glare, UV shielding, heat insulation, anti-static, conductivity, semi-mirror, hard coating, decoration, holography, etc.) to the surface of PET film, PEN film, acrylic film, polycarbonate film, or TAC film, etc., and they can be appropriately selected according to the purpose.

The thickness of the functional film as a specific substrate is determined in consideration of the application and light transmittance, but is preferably set to a value in the range of 10 to 300 μm. The reason is that if the thickness of the functional film is set to a value less than 10 μm, the mechanical strength and durability may be significantly reduced. On the other hand, if the thickness of the functional film is set to a value exceeding 300 μm, when used in a touch panel, the sensitivity may be reduced and the transmittance of the active energy line may be significantly reduced. Therefore, the thickness of the functional film is preferably set to a value in the range of 20 to 250 μm, and more preferably to a value in the range of 30 to 200 μm.

When the specific substrate is a release film, its type is, for example, at least one of a polyester film (PET film, etc.), an olefin film, an acrylic film, a urethane film, a polycarbonate film, a TAC film, a fluorine film, a polyimide film, etc. having a release surface. In addition, the release surface in this specification includes any one of a surface subjected to a release treatment and a surface showing release properties even without a release treatment.

The thickness of the release film as a specific substrate is determined in consideration of the application and light transmittance, but is preferably set to a value in the range of 10 to 300 μm. The reason is that if the thickness of the release film is set to a value less than 10 μm, the mechanical strength and durability may be significantly reduced. On the other hand, if the thickness of the release film is set to a value exceeding 300 μm, it may be difficult to wind it into a roll shape and handle it. Therefore, the thickness of the release film is preferably set to a value in the range of 20 to 250 μm, and more preferably set to a value in the range of 30 to 200 μm.

As the optical property of a specific substrate (functional film or release film, etc.), it is preferred to have appropriate transparency for use as a touch panel or liquid crystal display device. That is, as the lower limit of the visible light transmittance of the resin plate, it is preferably set to a value of 60% or more, more preferably to a value of 75% or more, and more preferably to a value of 85% or more. In addition, the upper limit of the visible light transmittance of the resin plate is preferably set to a value of 100% or less, more preferably to a value of 99.9% or less, more preferably to a value of 99% or less, and more preferably to a value of 98% or less.

4. Properties of the machinability enhancing layer (1) Storage elastic modulus (M1) before active energy ray irradiation The machinability enhancing layer of this embodiment preferably has a storage elastic modulus (M1) before active energy ray irradiation within a range of 0.01 to 1 MPa. The reason is that by controlling the storage elastic modulus (M1) within a specific range, the flexibility of the machinability enhancing layer before active energy ray irradiation can be made appropriate, and the adhesion to the resin board can be made good. Therefore, the storage elastic modulus (M1) before active energy ray irradiation is preferably set to a value within the range of 0.04 to 0.20 MPa, and further, based on the ease of achieving both durability and machinability after active energy ray irradiation, it is more preferably set to a value within the range of 0.07 to 0.08 MPa. In addition, unless otherwise specified, in this specification, it means the storage elastic modulus (M1, M2) equivalent to a temperature of 25°C (the same applies hereinafter).

(2) Storage elastic modulus (M2) after active energy ray irradiation The characteristic of the machinability enhancing layer of this embodiment is that the storage elastic modulus (M2) after active energy ray irradiation is set to a value of 0.20 MPa or more. The reason is that by controlling the storage elastic modulus (M2) to a value of 0.20 MPa or more, when the machinability enhancing film is attached to the resin plate and cut using a cutting device, the occurrence of defects and seepage from the machinability enhancing layer can be suppressed, thereby obtaining good cutting performance. Therefore, the lower limit of the storage elastic modulus (M2) is preferably set to a value of 0.22 MPa or more, more preferably set to a value of 0.25 MPa or more, and more preferably set to a value of 0.30 MPa or more. On the other hand, when the storage elastic modulus (M2) becomes excessively large, durability may be reduced. Therefore, the upper limit of the storage elastic modulus (M2) is preferably set to a value below 5MPa, more preferably to a value below 2MPa, particularly preferably to a value below 1MPa, and even more preferably to a value below 0.6MPa.

Here, referring to FIG. 2, the relationship between the storage elastic modulus (M2) and machinability of the machinability improvement layer after active energy ray irradiation is described. FIG. 2 is based on the evaluation results of the embodiment and comparative example described later, with the value of the storage elastic modulus (M2) (MPa) of the machinability improvement layer after active energy ray irradiation on the horizontal axis and the value of the machinability evaluation (relative value) on the vertical axis. In addition, the value of the machinability evaluation (relative value) is a relative value calculated by setting ◎ to 5 points, ○ to 3 points, △ to 1 point, and × to 0 points in the machinability evaluation of the embodiment and comparative example described later. As can be seen from FIG. 2, when the value of the storage elastic modulus (M2) is less than 0.2MPa, the value of the machinability evaluation (relative value) is 0 points, but when it is 0.20MPa or more, the value of the machinability evaluation (relative value) tends to increase. Furthermore, it can be seen that when the value of the storage elastic modulus (M2) falls between 0.25 and 0.3MPa, the value of the machinability evaluation (relative value) increases to about 3 to 5 points, and when it is above 0.3MPa, the value of the machinability evaluation (relative value) becomes the highest 5 points. Therefore, it can be seen from FIG. 2 that by setting the value of the storage elastic modulus (M2) after active energy ray irradiation to a relatively small value of 0.2MPa or more, relatively good machinability can be obtained, and the larger the value, the better the machinability.

(3) Increase rate of storage elastic modulus (M2/M1×100) The increase rate (M2/M1×100) of the storage elastic modulus (M2) of the machinability enhancement layer of this embodiment after active energy ray irradiation relative to the storage elastic modulus (M1) before active energy ray irradiation is usually preferably set to a value within the range of 320 to 30000%. The reason is that by controlling the increase rate (%) of the aforementioned storage elastic modulus to a value within a specific range, it is easy to achieve both adhesion to the resin board before active energy ray irradiation and durability and machinability before and after active energy ray irradiation. Therefore, the increase rate of the storage elastic modulus is more preferably set to a value within the range of 350 to 10000%, and more preferably set to a value within the range of 380 to 1000%.

(4) Gel fraction (G1) before active energy ray irradiation The gel fraction (G1) of the machinability enhancing layer of this embodiment before active energy ray irradiation is usually preferably set to a value within the range of 40 to 78%. The reason is that by controlling the gel fraction (G1) within a specific range, the adhesion to the resin board can be improved. More specifically, when the gel fraction (G1) is less than 40%, the cohesion of the machinability enhancing layer is insufficient, and the handling property of the machinability enhancing film may deteriorate. On the other hand, when the gel fraction (G1) is a value exceeding 78%, the machinability enhancement layer is over-hardened, and the adhesion to the resin board is deteriorated, and the durability is deteriorated. Therefore, the gel fraction (G1) is preferably set to a value within the range of 50 to 76%, and more preferably set to a value within the range of 60 to 72%. In addition, the method for determining the gel fraction (G1) is described in detail in the following embodiments.

(5) Gel fraction (G2) after active energy ray irradiation The gel fraction (G2) of the machinability-enhancing layer of the present embodiment after active energy ray irradiation is preferably set to a value of 60% or more. The reason is that when the gel fraction (G2) is controlled to a value below 60%, the machinability is significantly reduced and adhesive residues may occur. Therefore, the lower limit of the gel fraction (G2) is preferably set to a value of 70% or more, particularly preferably to a value of 75% or more, and even more preferably to a value of 77% or more. In addition, the upper limit of the gel fraction (G2) is not particularly limited and may be 100%, but from the viewpoint of both machinability and durability, it is preferably 95% or less, particularly preferably 90% or less. In addition, the method for measuring the gel fraction (G2) is described in detail in the examples described later.

(6) Increase rate of gel fraction (G2/G1×100) The increase rate of the gel fraction (G2) of the machinability enhancement layer after active energy ray irradiation relative to the gel fraction (G1) before active energy ray irradiation (=G2/G1×100) of the present embodiment is usually preferably set to a value within the range of 110 to 250%. The reason is that by controlling the increase rate of the gel fraction within a specific range, the adhesion to the resin board before active energy ray irradiation can be made better, and it is easy to have both durability and machinability after active energy ray irradiation. More specifically, if the increase rate of the gel fraction is a value less than 110%, the machinability is reduced, the machinability enhancement layer is damaged, and the durability is reduced. On the other hand, if the increase rate of the gel fraction exceeds 250%, the machinability-enhanced layer may become brittle and classified. Therefore, the increase rate of the gel fraction is preferably set to a value within the range of 114 to 200%, more preferably within the range of 120 to 160%, and particularly preferably within the range of 128 to 140%.

(7) Adhesion before active energy ray irradiation (P1) The adhesion (P1) of the machinability enhancement layer of this embodiment before active energy ray irradiation is preferably set to a value within the range of 1 to 60 N/25 mm. The reason is that by controlling the adhesion (P1) within a specific range, the adhesion to the resin board becomes better. If the adhesion (P1) is less than 1 N/25 mm, first, it becomes difficult to bond to the resin board, and even if bonding is attempted, the machinability enhancement layer may peel off from the resin board and easily cause defects. On the other hand, if the adhesion (P1) exceeds 60 N/25 mm, the handling property may deteriorate. Therefore, the adhesive force (P1) is preferably set to a value within the range of 8 to 40 N/25 mm, and more preferably set to a value of 15 to 30 N/25 mm. In addition, the adhesive force (P1) can be measured by the 180-degree peeling method according to JIS Z0237:2009 before active energy ray irradiation, but a more specific measurement method is shown in the following embodiment.

(8) Adhesion after active energy ray irradiation (P2) The characteristic of the machinability-enhancing layer of this embodiment is that the adhesion (P2) after active energy ray irradiation is set to a value of 10N/25mm or more. The reason is that by controlling the adhesion (P2) to a value of 10N/25mm or more, the adhesion is good and excellent durability is exhibited. Therefore, the lower limit of the adhesion (P2) is preferably set to a value of 15N/25mm or more, more preferably to a value of 20N/25mm or more, and more preferably to a value of 24N/25mm or more. On the other hand, the upper limit of the adhesive force (P2) is preferably set to a value below 200N/25mm, more preferably set to a value below 120N/25mm, more preferably set to a value below 60N/25mm, and particularly preferably set to a value below 40N/25mm. In addition, the adhesive force (P2) can be measured by the 180-degree peeling method according to JIS Z0237:2009 after irradiation with active energy rays, but a more specific measurement method is shown in the following embodiment.

(9) Increase rate of adhesive force (P2/P1×100) The increase rate of the adhesive force (P2) of the machinability enhancement layer of this embodiment after active energy ray irradiation relative to the adhesive force (P1) before active energy ray irradiation (=P2/P1×100) is preferably set to a value of 80 to 300%. The reason is that by controlling the increase rate of the adhesive force within a specific range, it is easier to achieve both the adhesion to the resin board before active energy ray irradiation and the durability after active energy ray irradiation. Therefore, the increase rate of the adhesive force (P2) is preferably set to a value within the range of 100 to 200%, and more preferably to a value within the range of 120 to 140%.

(10) Maximum stress (S2) The maximum stress (S2) of the machinability-enhancing layer of this embodiment when measuring the tensile stress after active energy ray irradiation is usually preferably set to a value of 1.5 N/mm ² or more. The reason is that by setting the maximum stress (S2) to a value of 1.5 N/mm ² or more, there is a tendency to suppress the damage of the machinability-enhancing layer during machining, and the machinability becomes good. Therefore, the maximum stress (S2) is more preferably set to a value of 2.0 N/mm ² or more, and from the viewpoint of durability, it is more preferably set to a value of 2.5 N/mm ² or more. On the other hand, the upper limit of the maximum stress (S2) is not particularly limited, but based on the viewpoint of both durability and machinability, it is preferably set to a value below 20N/ ^mm2 , more preferably to a value ^below 10N/mm2, and particularly preferably to a value below 4N/ ^mm2 .

(11) Stress at 100% elongation (E2) The stress at 100% elongation (E2) of the machinability-enhancing layer of this embodiment after irradiation with active energy rays is usually preferably set to a value of 10N/ ^mm2 or less. The reason is that by setting the stress at 100% elongation (E2) to a value of 10N/mm2 ^or less, the machinability-enhancing layer tends to be difficult to elongate during machining, and a cutting surface in which the machinability-enhancing layer does not ooze out after cutting can be obtained, thereby achieving good machinability. Therefore, the upper limit value of the stress at 100% elongation (E2) is preferably set to a value of 6N/mm2 or ^less , and from the viewpoint of durability, it is more preferably set to a value of 1N/mm2 or ^less . On the other hand, the lower limit of the stress at 100% elongation (E2) is not particularly limited, but from the perspective of both durability and machinability, it is preferably set to a value of 0.1 N/mm ² or more, more preferably set to a value of 0.4 N/mm ² or more, and particularly preferably set to a value of 0.7 N/mm ² or more.

5. Laminated body The laminated body using the machinability-enhanced film of the present embodiment is not particularly limited as long as it is a laminated body composed of a resin plate 12 formed by laminating a machinability-enhanced film 18 as shown in FIG. 1(a) and the like. Therefore, various functional films used in various machines can be easily manufactured into laminated bodies such as functional films attached to resin plates by machining (cutting) the machinability-enhanced layer and the resin plate with good precision. The laminated body is described in detail below.

(1) Laminated body before active energy ray curing The laminated body before active energy ray curing is a laminated body 10 formed by laminating a functional film as a specific substrate 16, a machinability-enhancing film 18, and a resin plate 12 in sequence, as shown in FIG. 1(a), FIG. 3(c), FIG. 4(d), and FIG. 5(d). In addition, the contents of FIG. 3 to FIG. 5 are used as a specific explanation of the method of using the machinability-enhancing film described later.

(2) Laminated body after active energy ray irradiation and curing The laminated body after active energy ray curing is formed by irradiating the laminated body before active energy ray curing with active energy ray from the specific substrate 16 or the resin plate 12 side, so that the machinability enhancing layer 14 is changed into the machinability enhancing layer 14' after curing. That is, as shown in Figs. 3(d) and 3(e), Figs. 4(e) and 4(f), and Figs. 5(e) and 5(f), the functional film as the specific substrate 16, the machinability enhancing layer 14' after curing, and the resin plate 12 are sequentially laminated to form a laminated body 10'.

The cured machinability enhancing layer 14' is the machinability enhancing layer 14 of the machinability enhancing film 18 that is cured by irradiation with active energy rays. In the present embodiment, the cured machinability enhancing layer 14' is formed by an adhesive having a crosslinked structure composed of a (meth)acrylate copolymer as a main agent (A) and a thermosetting component (B), and containing a structure (polymerized structure) that polymerizes and cures the active energy ray curing component (C). The polymerized structure is presumed to be a structure that entangles the crosslinked structure composed of a (meth)acrylate copolymer as a main agent (A) and a thermosetting component (B). By having a structure in which multiple three-dimensional structures are intertwined, the machinability-enhancing layer 14' after hardening becomes one with high cohesion, and becomes one that easily satisfies the desired values of adhesion and storage elasticity. Therefore, the machinability-enhancing layer 14' after hardening exhibits excellent cutting performance and also becomes one with excellent durability.

Furthermore, as long as the effect of the present invention can be obtained, the cured machinability enhancing layer 14' may also contain a photopolymerization initiator (D) that does not crack even when irradiated with active energy rays. In this embodiment, the residual amount of the photopolymerization initiator in the cured machinability enhancing layer 14' is preferably 0.1% by mass or less, and more preferably 0.01% by mass or less.

6. Method of use The method of using the machinability enhancing film 18 is as shown in Fig. 3(a) to (e), and preferably includes the following steps (1) to (4). (1) A composition containing an active energy ray-hardening component (derived from a resin layer 13 of a composition for forming a machinability enhancing layer) is applied to the surface of a functional film as a specific substrate 16, and a machinability enhancing film 18 having a machinability enhancing layer 14 having active energy ray hardening properties is prepared by heat treatment. (2) The obtained machinability enhancing film 18 is attached to The step of: (1) irradiating the resin plate 12 with active energy rays from the side of the resin plate 12 or the specific substrate 16 to harden the active energy ray-hardening component in the machinability enhancing layer 14 to form a hardened machinability enhancing layer 14'; (2) performing a specific machining treatment on the laminate 10' including the hardened machinability enhancing layer 14' and the resin plate 12. The following describes the method of using the machinability enhancing film 18 in detail with reference to appropriate figures.

6-1: Step (1)-1 Step (1)-1 is a step of preparing a composition for forming a machinability-enhancing layer. Therefore, the resin layer 13 derived from the composition for forming a machinability-enhancing layer shown in FIG. 3(a) is composed of a composition including a (meth)acrylate copolymer as a main agent (A), a thermosetting component (B), and an active energy ray-curing component (C) as main components. The composition may include a photopolymerization initiator (D), a silane coupling agent (E), and an organic solvent as required, and by uniformly mixing these, a coating liquid for forming the above-mentioned resin layer 13 can be obtained.

6-2: Step (1)-2 Step (1)-2 is a step of applying the coating liquid of the aforementioned specific composition. Therefore, as shown in FIG. 3(a), the coating liquid of the aforementioned composition is applied to the surface of a specific substrate 16 (functional film, etc.), and a laminated product is obtained in which the specific substrate 16 and the resin layer 13 derived from the composition for forming the machinability-enhancing layer are laminated. The method for applying the coating liquid is not particularly limited, and it can be carried out by a known method. For example, rod coating, scraper coating, roller coating, blade coating, die nozzle coating, gravure coating, etc. are exemplified. Next, as shown in FIG. 3( b ), a specific heat treatment (H) is performed to allow the functional groups contained in the main agent (A) to undergo a thermal crosslinking reaction with the thermosetting component (B) to form an active energy ray-curable machinability-enhancing layer 14, thereby obtaining a machinability-enhancing film 18. The heat treatment (H) can also simultaneously remove the solvent contained in the coating liquid of the aforementioned composition. At this time, specifically, the heating temperature of the heat treatment (H) is preferably 50 to 150°C, more preferably 70 to 120°C. In addition, the heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes. Furthermore, after the heat treatment, it is preferred to provide a curing period of about 1 to 2 weeks at room temperature (e.g., 23°C, 50%RH). By such heat treatment (and curing), the (meth)acrylate copolymer is well crosslinked through the heat-curable component (B) to form a crosslinked structure. That is, after these steps, the machinability-enhancing layer 14 is obtained by thermally crosslinking the resin layer 13 derived from the composition for forming the machinability-enhancing layer, and becomes the machinability-enhancing film 18. In addition, the content and properties of other components (active energy line curable component (C), photopolymerization initiator (D), silane coupling agent (E), etc.) contained in the composition for forming the machinability-enhancing layer do not change before and after the thermal crosslinking.

6-3: Step (2) Next, step (2) is a step of laminating the machinability enhancing film on the resin sheet. Therefore, as shown in FIG3(c), the resin sheet 12 and the machinability enhancing layer 14 of the machinability enhancing film 18 are laminated. The lamination of the resin sheet 12 and the machinability enhancing film 18 in this way can be performed using a known lamination method such as a lamination machine. Thereby, a laminate 10 is obtained in which the active energy ray-curable machinability enhancing layer 14 is sandwiched between a specific substrate (functional film, etc.) 16 and the resin sheet 12.

6-4: Step (3) Next, step (3) is an active energy ray irradiation step. Therefore, as shown in FIG. 3(d), active energy rays (L) such as ultraviolet rays are irradiated from the back side of the specific substrate 16. Thereby, the active energy ray-hardening component (C) in the machinability-enhancing layer 14 is hardened to form a hardened machinability-enhancing layer 14'. That is, a laminate 10' is obtained in which the hardened machinability-enhancing layer 14' is sandwiched between the specific substrate 16 (functional film, etc.) and the resin sheet 12. In addition, in Figure 3(d), the active energy ray (L) is irradiated from the back side of the resin plate 12, or it can also be irradiated from the side where a specific substrate 16 (functional film, etc.) is set, that is, the active energy ray (L) is irradiated from the side opposite to the back side, and further, the active energy ray (L) can also be irradiated from both the back side of the resin plate 12 and the specific substrate 16 (functional film, etc.) side.

Here, the so-called active energy ray refers to electromagnetic waves or charged particle beams that have energy, and specific examples include ultraviolet rays, electron beams, etc. As the active energy ray of this embodiment, it is preferably an active energy ray containing light with a wavelength of 200 to 450 nm. In order to obtain active energy rays that meet the above conditions, it is sufficient to use a light source that can irradiate ultraviolet rays, such as a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc. The irradiation amount of the active energy ray is preferably a value within the range of an illumination of 50 to 1000 mW/ ^cm2 . The light amount is preferably 50 mJ/ ^cm2 or more, more preferably 80 mJ/ ^cm2 or more, and more preferably 200 mJ/ ^cm2 or more. Moreover, the amount of light is preferably 10000 mJ/cm2 or ^less , more preferably 5000 mJ/cm2 or ^less , and even more preferably 2000 mJ/cm2 ^or less.

6-5: Step (4) Step (4) is a machining step. Therefore, as shown in FIG3(e), the resin sheet 12 having the machinability-enhancing layer 14' laminated thereon is subjected to a specific machining process (e.g., a cutting process in the direction indicated by arrow A) together with a specific substrate 16 (functional film, etc.). Therefore, since the machinability-enhancing film of the present embodiment has excellent machinability, a laminate having a specific shape can be easily obtained by a single cutting process. Furthermore, since the machinability-enhancing layer is not damaged or elongated during the cutting process, the cut surface after machining becomes good, and the obtained laminate becomes one having excellent appearance quality. In addition, the obtained laminate can also be applied to optical parts used in harsh environments (such as touch panels or liquid crystal display devices for vehicles, etc.) due to its excellent durability. Therefore, the machinability-enhanced film of this embodiment can be applied to optical parts such as touch panels or liquid crystal display devices by using it as described above, and a resin plate with a functional film attached through the machinability-enhanced layer can be easily manufactured.

7. Other methods of use 7-1 Variations The steps illustrated in FIG. 4(a) to (f) are examples of steps when a specific substrate 16' (peel-off film, etc.) is used in the aforementioned step (1). Therefore, for example, when a specific substrate 16' (peel-off film, etc.) is used, as illustrated in FIG. 4(a) to (f), by including the following steps (1') to (4'), it can be preferably used for machining (cutting) the machinability-enhancing film 18.

(1) Step (1') Step (1') is a heat treatment step. Therefore, as shown in FIG. 4(a) and FIG. 4(b), a resin layer 13 derived from a composition for forming a machinability-enhancing layer is applied to the surface of a specific substrate 16' (peel-off film, etc.), and a machinability-enhancing film 18' including a machinability-enhancing layer 14 is prepared by heat treatment (H). Here, the preparation step and the coating step of the composition for forming a machinability-enhancing layer are based on the aforementioned step (1)-1 and step (1)-2. In addition, although not shown, in FIG. 4(b), a specific substrate 16' (peel-off film, etc.) can also be provided on one surface of the machinability enhancement layer 14. By adopting such a configuration, the risk of contamination of the machinability enhancement layer 14 can be reduced until use.

(2) Step (2') Next, step (2') is a step of laminating the machinability enhancing film on the resin sheet. That is, as shown in Fig. 4(c) and Fig. 4(d), the exposed surface of the machinability enhancing layer 14 of the machinability enhancing film 18' is laminated to the specific substrate 16' (peel-off film, etc.). Then, the specific substrate 16' (peel-off film, etc.) is peeled off and the resin sheet 12 is laminated. Thus, a laminated body 10 is obtained in which the active energy ray-curable machinability enhancing layer 14 is sandwiched between the specific substrate 16 (functional film, etc.) and the resin sheet 12.

(3): Step (3') Next, step (3') is an active energy ray irradiation step. Therefore, as shown in FIG4(e), the active energy ray (L) is irradiated to harden the active energy ray hardening component (C) contained in the machinability enhancing layer 14 to form the machinability enhancing layer 14'. That is, a laminate 10' is obtained in which the hardened machinability enhancing layer 14' is clamped between a specific substrate 16 (functional film, etc.) and a resin sheet 12. In addition, the irradiation conditions of the active energy ray are based on the aforementioned step (3).

(4): Step (4') Step (4') is a machining step. Therefore, as shown in FIG. 4(f), the resin sheet 12 having the machinability enhancing layer 14' laminated thereon is subjected to a specific machining process (e.g., cutting process in the direction indicated by arrow A) together with a specific substrate 16 (functional film, etc.). In addition, in the above steps (1') to (4'), the machinability enhancing film of the present embodiment can be preferably used as in the above steps (1) to (4). Therefore, in this variation 1, it can also be applied to optical parts such as touch panels or liquid crystal display devices, and a resin sheet with a functional film attached thereto through a machinability enhancing layer can be easily manufactured.

7-2 Variation 2 The steps illustrated in FIG. 5(a) to (f) are steps in which the bonding order of the machinability enhancement film 18' is different from that of step (2') of variation 1 described above. That is, as shown in FIG. 5(c), one side of the machinability enhancement layer 14 of the machinability enhancement film 18' shown in FIG. 5(b) is bonded to the resin sheet 12 and laminated. Next, as shown in FIG. 5(d), the specific substrate 16' (peel-off film, etc.) is peeled off and the specific substrate 16 (functional film) is laminated. In addition, except for the above step (2'), the above variation 1 is followed. Therefore, in this variation 2, the machinability-enhanced film of this embodiment can be used preferably, as in the above steps (1) to (4) and the above steps (1') to (4'). Therefore, the above steps (1') to (4') can also be applied to optical parts such as touch panels or liquid crystal display devices, and a resin plate with a functional film attached through a machinability-enhanced layer can be easily manufactured. [Example]

The following reference examples will be used to explain in more detail the machinability-enhancing film of this embodiment and the method of using the machinability-enhancing film. However, this embodiment is not limited to the description of these embodiments without any special reason.

[Example 1] 1. Preparation and use of a film with improved machinability 1-(1) Preparation of main agent (A) The total amount of the monomer components was set to 100 parts by weight, and 30 parts by weight of butyl acrylate, 25 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of isobornyl acrylate, 5 parts by weight of methyl methacrylate, 5 parts by weight of acrylamide and 25 parts by weight of 2-hydroxyethyl acrylate were solution polymerized to prepare a (meth)acrylate copolymer as the main agent (A). The weight average molecular weight (Mw) of the obtained (meth)acrylate copolymer was 500,000 as measured by the method shown below.

The weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured using a gel permeation chromatography (GPC) under the following conditions (GPC measurement). (Measurement conditions) ・GPC measurement apparatus: HLC-8020 manufactured by TOSOH ・GPC column (passed in the following order): manufactured by TOSOH TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL ・Measurement solvent: tetrahydrofuran ・Measurement temperature: 40°C

In addition, the details of the abbreviations listed in Table 1 are as follows. (Main agent (A): ((meth)acrylate copolymer)) BA: Butyl acrylate 2EHA: 2-ethylhexyl acrylate IBXA: Isobornyl acrylate MMA: Methyl methacrylate ACMO: N-acryloylmorpholine HEA: 2-hydroxyethyl acrylate AA: Acrylic acid 4HBA: 4-hydroxybutyl acrylate HEMA: 2-hydroxyethyl methacrylate

1-(2) Preparation of a composition for forming a machinability-enhancing layer Next, 100 parts by weight of a (meth)acrylate copolymer (solid component) as a main agent (A) was mixed with 0.3 parts by weight of trihydroxymethylpropane-modified toluene diisocyanate as a thermosetting component (B), 8 parts by weight of ε-caprolactone-modified tris(2-acryloyloxyethyl)isocyanurate as an active energy ray-curable component (C), 0.8 parts by weight of 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide as a photopolymerization initiator (D), and 0.3 parts by weight of 3-glycidyloxypropyltrimethoxysilane as a silane coupling agent (E) in the following proportions, stirred until uniform, and diluted with methyl ethyl ketone to obtain a coating solution having a solid component concentration of 30% by weight.

In addition, the details of the abbreviations listed in Table 2 are as follows. (Thermosetting component (B)) B1: Trihydroxymethylpropane modified toluene diisocyanate B2: Trihydroxymethylpropane modified xylene diisocyanate B3: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (Active energy ray curing component (C)) C1: ε-caprolactone modified tris(2-acryloyloxyethyl) isocyanurate C2: Trihydroxymethylpropane triacrylate C3: Dipentaerythritol hexaacrylate

1-(3) Formation step of the machinability-enhancing layer On the peeling-treated surface of a heavy-peel release film (manufactured by LINTEC, product name "SP-PET752150"), one side of which was peeled with a silicone-based release agent, the obtained coating solution was applied using a rod coater in such a manner that the thickness after drying became 15 μm. Then, the coating layer was heat-treated at 90°C for 1 minute to perform a thermal crosslinking reaction, thereby forming a machinability-enhancing layer having a crosslinked structure composed of a (meth)acrylate copolymer as a main agent (A) and a thermosetting component (B).

Next, the coating layer on the heavy-peel release film obtained above was laminated with a light-peel release film (manufactured by LINTEC, product name "SP-PET382120") of polyethylene terephthalate film with one side treated with a silicone release agent, with the release-treated surface of the light-peel release film in contact with the machinability-enhancing layer, and cured for 7 days at 23°C and 50% RH to produce an evaluation machinability-enhancing film consisting of a heavy-peel release film/machinability-enhancing layer (thickness: 15μm)/light-peel release film. The thickness of the machinability-enhancing layer is a value measured using a constant-pressure thickness gauge (manufactured by TECLOCK, product name "PG-02") in accordance with JIS K7130.

2. Evaluation of machinability-enhancing film 2-(1) Determination of adhesion (P1) before active energy ray irradiation In the machinability-enhancing film for evaluation, a light-peel release film was peeled off from the machinability-enhancing layer and attached to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100μm) to obtain a laminate of a heavy-peel release film/machinability-enhancing layer (15μm)/PET film. The obtained laminate was cut into 25 mm wide and 150 mm long pieces and used as samples. At 23°C and 50% RH, the heavy-peel peeling sheet was peeled off from the sample obtained above, and the exposed mechanical processing improvement layer was attached to a glass plate, and then pressed with a 2kg roller with one back and forth piercing. After being placed at 23°C and 50% RH for 24 hours, the adhesion (P1, N/25mm) was measured using a tensile tester (TENSILON, manufactured by ORIENTEC) at a peeling speed of 300mm/min and a peeling angle of 180 degrees. In addition, the conditions other than those described here were measured in accordance with JIS Z 0237:2000. The results are shown in Table 2.

2-(2) Measurement of Adhesion (P2) after Active Energy Ray Irradiation In an environment of 23°C and 50%RH, a heavy-peel type peeling sheet was peeled off from the sample obtained above, and the exposed mechanical processing improvement layer was attached to a glass plate. Then, it was pressed with a 2 kg roller moving back and forth once, and ultraviolet rays as active energy rays were irradiated from the PET film side under the following conditions. After being left at 23°C and 50%RH for 24 hours, the adhesion (P2, N/25mm) after active energy ray irradiation was measured using a tensile tester (TENSILON, manufactured by ORIENTEC) at a peeling speed of 300 mm/min and a peeling angle of 180 degrees. The conditions other than those described here were measured in accordance with JIS Z 0237:2000. The results are shown in Table 2. <Ultraviolet irradiation conditions> ・High-pressure mercury lamp was used. ・Illuminance: 200mW/cm ² , light quantity: 2000mJ/cm ²・UV illuminance/light meter: "UVPF-A1" manufactured by EYE GRAPHICS

2-(3) Calculation of the increase rate of adhesive force The increase rate of the adhesive force (P2) after the active energy ray irradiation measured above relative to the adhesive force (P1) before the active energy ray irradiation was calculated (=P2/P1×100, %). The results are shown in Table 2.

2-(4) Determination of gel fraction (G1) before active energy ray irradiation In the obtained evaluation machinability-enhancing film, only the machinability-enhancing layer was wrapped in a polyester mesh (mesh size 200), and its mass was weighed with a precision balance. By subtracting the mass of the mesh alone, the mass of only the machinability-enhancing layer was calculated. The mass at this time was set as m1. Next, the machinability-enhancing layer wrapped in a polyester mesh prepared by the above method was immersed in ethyl acetate at room temperature (23°C) for 72 hours. Then, the machinability-enhancing layer wrapped in the polyester mesh was taken out and air-dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, and then dried in an oven at 80°C for 12 hours. After drying, the weight was measured with a precision balance, and the mass of the machinability-enhancing layer alone was calculated by subtracting the mass of the mesh alone. The mass at this time was set as m2. Based on the mass calculated above, the gel fraction (G1) of the machinability-enhancing layer before active energy ray irradiation was derived (=(m2/m1)×100,%). The results are shown in Table 2.

2-(5) Determination of gel fraction (G2) after active energy ray irradiation The obtained evaluation machinability enhancement film peeling light peel type peeling film was directly irradiated with active energy rays under the above conditions to harden the machinability enhancement layer. The gel fraction (G2) of the machinability enhancement layer after active energy ray irradiation was derived in the same manner as above for the hardened machinability enhancement layer. The results are shown in Table 2.

2-(6) Calculation of the increase rate of gel fraction The increase rate of the gel fraction (G2) after the active energy ray irradiation relative to the gel fraction (G1) before the active energy ray irradiation was calculated (=G2/G1×100, %). The results are shown in Table 2.

2-(7) Measurement of maximum stress (S2) and stress at 100% elongation (E2) The obtained evaluation machinability-enhancing film was peeled off from the light-peel release type peeling film, and the exposed machinability-enhancing layer was directly irradiated with active energy rays under the above conditions to harden the machinability-enhancing layer. The maximum stress (S2, N/mm 2 ) and stress at 100% elongation (E2, N/mm ² ) were measured only for the hardened machinability-enhancing layer using a tensile testing machine (TENSILON manufactured by ORIENTEC, peeling speed 200 mm/ ^min ). The conditions other than those described here were measured in accordance with JIS K 7162-2:2014. The results are shown in Table 2.

2-(8) Determination of storage elastic modulus (M1) before active energy ray irradiation Among the obtained machinability-enhancing films for evaluation, only the machinability-enhancing layer was measured for storage elastic modulus (M1, MPa (25°C)) before active energy ray irradiation using a viscoelasticity measuring device (ARES, manufactured by TA INSTRUMENTS, frequency 1 Hz) in accordance with JIS K7244-4:1999. The results are shown in Table 2.

2-(9) Determination of storage elastic modulus (M2) after active energy ray irradiation The obtained evaluation machinability-enhancing film was peeled off from the light-peel type peelable film, and the exposed machinability-enhancing layer was directly irradiated with active energy rays under the above conditions to harden the machinability-enhancing layer. Only for the hardened machinability-enhancing layer, the storage elastic modulus (M2, MPa (25°C)) of the machinability-enhancing layer after active energy ray irradiation was measured under the same conditions as above. The results are shown in Table 2.

2-(10) Calculation of the increase rate of storage elastic modulus The increase rate of the storage elastic modulus (M2) after the active energy ray irradiation measured above relative to the storage elastic modulus (M1) before the active energy ray irradiation was calculated (=M2/M1×100, %). The results are shown in Table 2.

2-(11) Evaluation of cutting properties The obtained evaluation film for improving machinability was peeled off from a light peeling type peeling sheet, and the exposed machinability improving layer was attached to a PET film (100 μm). Furthermore, the heavy peeling type peeling sheet was peeled off, and the exposed machinability improving layer was attached to a PET film (100 μm), thereby obtaining a test piece. After irradiating the test piece with active energy rays under the above conditions to harden the machinability improving layer, a cutter was used to cut one of the PET film surfaces of the test piece in a vertical direction. The cut surface was then observed under a microscope, and the cutting properties were evaluated according to the following criteria. ◎: No defects or elongation were observed in the machinability improving layer, and the test piece was a good cutting surface. ○: Slightly observed defects or elongation in the machinability improvement layer, which is a practically acceptable cutting surface. △: Defects or elongation in the machinability improvement layer, which is a practically unsuitable cutting surface. ×: Defects or elongation in the machinability improvement layer, which is a practically unsuitable cutting surface.

2-(12) Evaluation of durability The obtained evaluation film with improved machinability was peeled off from a light-peel release sheet, and the exposed machinability-enhancing layer was attached to the polycarbonate side of a resin plate (thickness: 1 mm, containing an ultraviolet absorber) on which polymethyl methacrylate (PMMA) and polycarbonate (PC) were layered. Furthermore, the evaluation film with improved machinability was peeled off from a heavy-peel release sheet, and the exposed machinability-enhancing layer was attached to a TAC film (thickness: 100 μm) as a functional film to obtain a test piece. The obtained test piece was autoclaved for 30 minutes at 50°C and 0.5MPa, and then placed at normal pressure, 23°C, and 50%RH for 24 hours. Next, the active energy beam was irradiated under the above conditions to harden the machinability-enhancing layer, and then stored at high temperature and high humidity conditions of 85°C and 85%RH for 500 hours. Then, the ridges and peeling at the interface between the machinability-enhancing layer and the adherend were visually confirmed, and the durability was evaluated according to the following criteria. The results are shown in Table 2. ◎: Neither bubbles nor ridges and peeling could be confirmed. ○: Slightly small bubbles occurred, but larger bubbles or peeling could not be confirmed. △: Moderate bubbles occurred, and larger bubbles or peeling were slightly confirmed. ×: Large bubbles or swelling and peeling were clearly observed.

[Examples 2 to 9, Comparative Examples 1 to 4] Except that the composition and molecular weight of the (meth)acrylate copolymer as the main agent (A), the weight and amount of the thermosetting component (B), the type and amount of the active energy ray-curing component (C), the amount of the photopolymerization initiator (D), and the amount of the silane coupling agent (E) were changed as shown in Table 1, a film with improved machinability was obtained in the same manner as in Example 1, and the film with improved machinability was evaluated. The results are shown in Table 2.

[Industrial Availability]

As described above, according to the machinability enhancement film of the present invention, by setting the storage elastic modulus (M2) of the machinability enhancement layer attached to a specific resin plate and then irradiated with active energy rays to a specific value, good machinability can be obtained when the machinability enhancement layer is cut while the resin plate is included in the mechanical processing device. In addition, according to the machinability enhancement film of the present invention, by setting the adhesion (P2) of the machinability enhancement layer after irradiation with active energy rays to a specific value, good durability can be obtained.

Therefore, a machinability-enhancing film having such a machinability-enhancing layer, a laminate including such a machinability-enhancing layer (resin sheet with a machinability-enhancing film attached thereto), and an efficient method for using such a machinability-enhancing film can be provided. Therefore, the machinability-enhancing film of the present invention can be expected to contribute to the improvement of production efficiency or quality in touch panels or liquid crystal display devices, etc.

10, 10': Laminated body 12: Resin sheet 13: Resin layer derived from a composition for forming a machinability-enhancing layer 14: Machinability-enhancing layer 14': Machinability-enhancing layer after curing 14a: Specific space 16: Specific substrate (functional film, etc.) 16': Specific substrate (peel-off film, etc.) 18, 18': Machinability-enhancing film

Figures 1(a) to (b) are diagrams for respectively explaining the configuration examples of a laminate formed using a machinability-enhancing film. Figure 2 is a diagram for explaining the relationship between the storage elastic modulus (MPa) and the machinability (relative value) of the machinability-enhancing layer after irradiation with active energy rays. Figures 3(a) to (e) are diagrams for explaining the method for manufacturing a machinability-enhancing film including a thermal crosslinking step and the method for manufacturing a laminate using the machinability-enhancing film. Figures 4(a) to (f) are diagrams for explaining the manufacturing steps and use steps of a laminate formed using a machinability-enhancing film using a functional film as a specific substrate (part 1). 5(a) to (f) are diagrams for explaining the manufacturing steps and use steps of another laminate formed by using a release film as a specific substrate and a machinability-enhancing film (part 2).

10: Layered body

12: Resin board

14: Machinability improvement layer

14a: Specific space

16: Specific substrates (functional films, etc.)

18, 18’: Films to improve machinability

Claims (8)

A machinability enhancing film is attached to a resin plate and has an active energy ray-curable machinability enhancing layer formed by laminating on a specific substrate, wherein the thickness of the machinability enhancing layer is within a range of 3 to 40 μm, the machinability enhancing layer is obtained from a composition comprising a (meth)acrylate copolymer as a main agent (A), a thermosetting component (B) and an active energy ray-curable component (C), and the machinability enhancing layer is attached to the resin plate. For the machinability enhancement layer, the storage elastic modulus of the aforementioned machinability enhancement layer before active energy ray irradiation is set as M1, and the storage elastic modulus of the aforementioned machinability enhancement layer after active energy ray irradiation is set as M2, so that the value represented by M2/M1×100 is within the range of 320~30000%, the storage elastic modulus after active energy ray irradiation is a value of 0.2MPa or more, and the adhesive force after active energy ray irradiation is a value of 10N/25mm or more. The machinability-enhanced film of claim 1, wherein the aforementioned specific substrate comprises a functional film or a release film. For example, the machinability-enhanced film of claim 1, wherein the gel fraction of the aforementioned machinability-enhanced layer after irradiation with active energy rays is a value of 60% or more. For example, the machinability-enhanced film of claim 1, wherein the storage elastic modulus of the machinability-enhanced layer before irradiation with active energy rays is a value within the range of 0.01 to 1 MPa. For example, the machinability-enhanced film of claim 1, wherein the storage elastic modulus of the aforementioned machinability-enhanced layer after irradiation with active energy rays is a value within the range of 0.2~5MPa. A laminated body characterized by attaching a machinability-enhancing film as in claim 1 to a resin board. As in claim 6, the laminate, wherein the resin sheet is an optical resin sheet. A method for using a machinability-enhancing film as claimed in claim 1, characterized in that it comprises the following steps (1) to (4): (1) coating a composition containing an active energy ray-hardening component on the surface of a functional film as a specific substrate, and preparing a machinability-enhancing film having an active energy ray-hardening machinability-enhancing layer by heat treatment; (2) attaching the aforementioned machinability-enhancing film to a resin board; (3) irradiating the resin board or the specific substrate side with active energy rays to harden the active energy ray-hardening component in the aforementioned machinability-enhancing layer to prepare a hardened machinability-enhancing layer; (4) performing a specific machining treatment on a laminate comprising the hardened machinability-enhancing layer and the resin board.