JP2018158990A - Adhesive composition for decorative film, decorative film and decorative molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for a decorative film suppressing tackiness after heating and cooling to be low, and capable of forming an adhesive layer having a high adhesive force to an adherend of low polarity, and also to provide a decorative film and a decorative molding having the adhesive layer.SOLUTION: An adhesive composition for a decorative film includes: a (meth)acrylic polymer of 100 pts.mass in which a content of a constitutional unit derived from a tert-butyl (meth)acrylate is 25-65 mass% with regard to entire constitutional units, a content of a constitutional unit derived from a monomer having a carboxy group is 8 mass% or less with regard to the entire constitutional units; a tackifier resin of 30-50 pts.mass; and a crosslinking agent at a content of less than 10 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition for a decorative film, a decorative film, and a decorative molded product.

  As a method for decorating a molded body having a three-dimensional curved surface (hereinafter also referred to as an “adhered body”) such as an automobile interior product, a vacuum molding method, a pressure molding method, and the like are known. In the vacuum forming method, the pressure forming method, etc., the decorative film is heated to, for example, 100 ° C. or more, stretched in a softened state, pressed onto the adherend, and then cooled to room temperature (hereinafter, such treatment is referred to as “heating and cooling”). Also called.). Then, trimming is performed on unnecessary portions of the decorative film.

In general, acrylonitrile-butadiene-styrene resin (hereinafter also referred to as “ABS resin”) is used as the material of the adherend. In recent years, in order to reduce the weight of automobile interior parts, a case where a polypropylene resin (hereinafter also referred to as “PP resin”) having a low specific gravity and excellent thermoformability is used as an adherend is increasing. Therefore, there is a demand for a decorative film capable of decorating a PP resin having a low polarity.
Since an adhesive is used for adhering the decorative film and the adherend, the decorative film often has at least a base material layer and an adhesive layer.

  As a decorative film, for example, a vacuum comprising a base material, a decorative layer, an acrylic pressure-sensitive adhesive, and a pressure-sensitive adhesive layer comprising a tackifier having a softening point of 90 ° C. to 180 ° C. in this order. A decorative film for molding is disclosed (see, for example, Patent Document 1).

  As the decorative film adhesive, for example, an acrylic adhesive containing a copolymer of n-butyl acrylate: acrylic acid = 95: 5 and a curing agent is disclosed (for example, see Patent Document 2). In addition, as a decorative film adhesive, for example, a so-called blend-type adhesive composition containing two kinds of acrylic polymers is disclosed (for example, see Patent Document 3).

JP 2012-213894 A Japanese Patent Application Laid-Open No. 2015-196289 JP 2009-35588 A

  In general, the pressure-sensitive adhesive layer provided in the decorative film is required to have a low tack after heating and cooling in order to easily perform trimming. Further, since the decorative film is stretched during heating, a stress that tends to return to the original during cooling works, so that unexpected peeling is likely to occur. For this reason, it is calculated | required for the adhesive layer with which a decorating film is provided that the adhesive force with respect to the to-be-adhered body after heating and cooling is high.

None of the above-mentioned Patent Documents 1 to 3 has been studied on the material of the adherend, and therefore, the adherend having a low polarity such as PP resin may be peeled off.
Specifically, when the inventors examined, in the decorative film for vacuum forming described in Patent Document 1, no study was made on the composition and physical properties of the acrylic pressure-sensitive adhesive. For this reason, there are cases where the tackiness is high after heating and cooling and the workability is inferior, or the adhesive strength after cooling is low and unexpected peeling occurs.
In addition, the acrylic pressure-sensitive adhesive described in Patent Document 2 and the pressure-sensitive adhesive composition described in Patent Document 3 have a low adhesive force with respect to an adherend having a low polarity such as PP resin, and may cause unexpected peeling. .

  The present invention has been made in view of the above-described problems, and can provide a pressure-sensitive adhesive for a decorative film that can form a pressure-sensitive adhesive layer that has low tack after heating and cooling and has high adhesion to an adherend with low polarity. It is an object to provide a decorative composition, a decorative film having a pressure-sensitive adhesive layer, and a decorative molded product.

Means for solving the above problems include the following embodiments.
<1> The content rate of the structural unit derived from the monomer which has the content rate of the structural unit derived from tert-butyl (meth) acrylate is 25 mass%-65 mass% with respect to all the structural units, and has a carboxy group. Including 100 parts by mass of a (meth) acrylic polymer that is 8% by mass or less based on the total structural unit, and 30 parts by mass to 50 parts by mass of the tackifier resin, and the content of the crosslinking agent is less than 10 parts by mass. A pressure-sensitive adhesive composition for a decorative film.
<2> The decorative film adhesive composition according to <1>, wherein the tackifying resin has a softening point of 70 ° C to 130 ° C.
<3> The pressure-sensitive adhesive composition for a decorative film according to <1> or <2>, wherein the glass transition temperature of the (meth) acrylic polymer is −40 ° C. to −5 ° C.
<4> Any one of <1> to <3>, wherein the content of the structural unit derived from the monomer having a carboxy group in the (meth) acrylic polymer is 0.05% by mass or more based on the total structural unit. The pressure-sensitive adhesive composition for decorative film <5> according to any one of <1> to <4>, wherein the tackifying resin is at least one selected from a terpene resin and a rosin resin. A pressure-sensitive adhesive composition for a decorative film.
<6> For the decorative film according to any one of <1> to <5>, wherein the content of the crosslinking agent is 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer. Adhesive composition.
<7> The pressure-sensitive adhesive composition for a decorative film according to <6>, wherein the gel fraction after crosslinking is less than 50% by mass.
The decorative film which has a <8> base material and the adhesive layer formed from the adhesive composition for decorative films as described in any one of <1>-<7>.
<9> A decorative molded product having a molded body and the decorative film according to <8> arranged on the molded body.

  According to the present invention, the pressure-sensitive adhesive composition for a decorative film capable of forming a pressure-sensitive adhesive layer having a low tackiness after heating and cooling and having a high adhesion to a low-polarity adherend, and the pressure-sensitive adhesive layer It is possible to provide a decorative film and a decorative molded product having

Embodiments that are examples of the present invention will be described below.
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In addition, in the present specification, the amount of each component in the composition corresponds to that component unless a particular notice is given when a plurality of substances corresponding to each component are used in combination in the pressure-sensitive adhesive composition for decorative film. It means the total amount of multiple types of substances.
(Meth) acryl means at least one of acryl and methacryl, and (meth) acrylate means at least one of acrylate and methacrylate.
The pressure-sensitive adhesive composition for decorative film is a composition before the crosslinking reaction between the (meth) acrylic polymer and the crosslinking agent is completed, and means, for example, a liquid, pasty or powdery composition. .
The pressure-sensitive adhesive layer means a layer formed by applying and drying a pressure-sensitive adhesive composition. In one embodiment, the layer is a layer after the (meth) acrylic polymer and the crosslinking agent are substantially crosslinked, for example, a solid or gel layer.

≪Adhesive composition for decorative film≫
The pressure-sensitive adhesive composition for a decorative film of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive composition”) has a content of structural units derived from tert-butyl (meth) acrylate of 25 based on the total structural units. 100% by mass of a (meth) acrylic polymer that is from mass% to 65% by mass and the content of the structural unit derived from the monomer having a carboxy group is 8% by mass or less based on the total structural units, and tackifying 30 mass parts to 50 mass parts of resin, and content of a crosslinking agent is less than 10 mass parts.
The pressure-sensitive adhesive composition of the present invention comprises a (meth) acrylic polymer containing at least a structural unit derived from a specific amount of tert-butyl (meth) acrylate and a structural unit derived from a monomer having a specific amount of carboxy group, A specific amount of tackifying resin, and the content of the crosslinking agent is not more than a specific amount, so that it exhibits excellent adhesion to adherends formed from resins with low polarity such as PP resin. And it is possible to keep the tack after heating and cooling low.
The reason for this is not clear, but is presumed as follows.

  The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention contains 25 mass% to 65 mass% of structural units derived from tert-butyl (meth) acrylate with respect to the total structural units. In particular, since tert-butyl (meth) acrylate has a low polarity, the (meth) acrylic polymer of the present invention has a low polarity compared to a general (meth) acrylic polymer, and has a low polarity. There is a tendency that the compatibility with is improved.

The pressure-sensitive adhesive composition of the present invention contains 30 to 50 parts by mass of a tackifier resin. As above-mentioned, tackifying resin shows high compatibility with the (meth) acrylic-type polymer which the adhesive composition of this invention contains. Therefore, although the pressure-sensitive adhesive composition of the present invention contains a relatively large amount of tackifying resin of 30 to 50 parts by mass, it is difficult to bleed out even during heating in which the tackifying resin tends to bleed out. It tends to stay on the surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention can maintain an excellent adhesive force even on an adherend having a low polarity by the tackifier resin localized on the surface layer.
Further, since the pressure-sensitive adhesive composition of the present invention contains a relatively large amount of tackifying resin, the amount of the tackifying resin remaining in the vicinity of the surface layer of the pressure-sensitive adhesive layer is increased, and the temperature of tack development is in a region higher than room temperature. It becomes easy to move and it becomes possible to suppress the tack after heating and cooling to a lower level.
In general, when the tackifier resin bleeds out, the adhesive strength of the adhesive layer tends to decrease.

  Moreover, the glass transition temperature (Tg) of tert-butyl (meth) acrylate which comprises the (meth) acrylic-type polymer used by this invention exists in a temperature range higher than room temperature (25 degreeC). The (meth) acrylic polymer of the present invention can increase the glass transition temperature (Tg) of the (meth) acrylic polymer by including a structural unit derived from a specific amount of tert-butyl (meth) acrylate. It becomes. If the Tg value of the (meth) acrylic polymer is high, the temperature range where tack due to the tackifier resin develops moves to a higher temperature side than room temperature, so it is presumed that the tack after heating and cooling can be kept low. .

In the pressure-sensitive adhesive composition of the present invention, the blending amount of the crosslinking agent is adjusted within a predetermined range, and the content of the structural unit derived from the monomer having a carboxy group constituting the (meth) acrylic polymer is predetermined. It is adjusted within the range. For this reason, the pressure-sensitive adhesive layer formed from this pressure-sensitive adhesive composition does not have an excessively high cross-linking density, does not have a high cohesive force, and easily wets and spreads on the irregularities of the adherend during heating. There is a tendency to have excellent adhesive strength.
The pressure-sensitive adhesive composition of the present invention is presumed that each component is combined to form a pressure-sensitive adhesive layer having high adhesion to an adherend with low polarity and low tack after heating and cooling.
In addition, if the Tg of the (meth) acrylic polymer is high, the cohesive force at high temperatures tends to be high, so the decorative film of the present invention is less likely to wrinkle, foam, etc., and tends to be excellent in appearance. is there.

  In addition, in this specification, the external appearance of the decorative film after decorating a molded object may only be described as "external appearance". The decorative film is preferably excellent in appearance with few wrinkles and foaming after decoration of the molded product.

<(Meth) acrylic polymer>
In the (meth) acrylic polymer used in the present invention, at least the content of the structural unit derived from tert-butyl (meth) acrylate is 25% by mass to 65% by mass with respect to all the structural units, and a carboxy group The content rate of the structural unit derived from the monomer which has is 8 mass% or less with respect to all the structural units.

  The (meth) acrylic polymer used in the present invention preferably contains a structural unit derived from tert-butyl acrylate from the viewpoint of keeping the compatibility with the tackifier resin described later and the tack after heating and cooling low.

The content rate of the structural unit derived from tert-butyl (meth) acrylate in the (meth) acrylic polymer used in the present invention is 25% by mass to 65% by mass with respect to all the structural units. If the content of the structural unit derived from tert-butyl (meth) acrylate is less than 25% by mass, the glass transition temperature of the (meth) acrylic polymer becomes too high, and the tack after heating and cooling can be kept low. Have difficulty.
Moreover, when the content rate of the structural unit derived from tert-butyl (meth) acrylate exceeds 65 mass%, the glass transition temperature (Tg) of a (meth) acrylic-type polymer will become high too much, and from an adhesive composition. There is a tendency that the adhesive strength of the formed pressure-sensitive adhesive layer cannot be obtained sufficiently.
From the viewpoint of suppressing the tack after heating and cooling and improving the adhesive strength, the content of the structural unit derived from tert-butyl (meth) acrylate in the (meth) acrylic polymer used in the present invention is all structural units. 30% by mass to 60% by mass is preferable, 35% by mass to 55% by mass is more preferable, and 40% by mass to 50% by mass is still more preferable.

Examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, succinic acid monohydroxyethyl (meth) acrylate, and maleic acid. Monohydroxyethyl (meth) acrylate, monohydroxyethyl fumarate (meth) acrylate, phthalate monohydroxyethyl (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic acid dimer, ω-carboxy-polycaprolactone mono (meth) acrylate.
Among these, from the viewpoint of keeping the tack after heating and cooling low and improving the adhesive force, as the (meth) acrylic monomer having a carboxy group, acrylic acid, methacrylic acid, ω-carboxy-polycaprolactone mono ( At least one selected from (meth) acrylate is preferable, and at least one of acrylic acid and methacrylic acid is more preferable.
In addition, the monomer which has a carboxy group may be used individually by 1 type, and may use 2 or more types together.

The content rate of the structural unit derived from the monomer which has a carboxy group in the (meth) acrylic-type polymer used by this invention is 8 mass% or less with respect to all the structural units. When the content of the structural unit derived from the monomer having a carboxy group exceeds 8% by mass, the cross-linking reaction between the (meth) acrylic polymer and the cross-linking agent proceeds excessively when the cross-linking agent is included. There is a tendency that the pressure-sensitive adhesive layer formed from the composition becomes too hard and sufficient adhesive strength cannot be obtained.
The (meth) acrylic polymer used in the present invention may not substantially contain a structural unit derived from a monomer having a carboxy group.
Here, “substantially free” means that the presence of a (meth) acrylic polymer containing a structural unit derived from a monomer having a carboxy group inevitably mixed is allowed. It means that the presence of a (meth) acrylic polymer containing a structural unit derived from the monomer it has is not allowed.
Containing a structural unit derived from a monomer having a carboxy group in the (meth) acrylic polymer used in the present invention from the viewpoint of imparting appropriate hardness to the pressure-sensitive adhesive layer and suppressing shrinkage of the decorative sheet during heating and cooling. The rate is preferably 0.01% by mass or more, more preferably 0.05% by mass or more with respect to all the structural units. From the viewpoint of reducing tack after heating and cooling and improving adhesive strength, 0.1% by mass to 6 mass% is particularly preferable, and 0.5 mass% to 3 mass% is most preferable.
In addition, when a (meth) acrylic-type polymer contains the structural unit derived from the monomer which has a carboxy group, from a viewpoint of giving a cohesive force to an adhesive layer and improving an external appearance, a crosslinking agent is included in an adhesive composition. It is preferable to include.

  The (meth) acrylic polymer used in the present invention includes a structural unit derived from an alkyl (meth) acrylate other than tert-butyl (meth) acrylate (hereinafter also referred to as “other alkyl (meth) acrylate”). May be.

  As other alkyl (meth) acrylate, unsubstituted alkyl (meth) acrylate is preferable, and the kind is not particularly limited. The alkyl group of other alkyl (meth) acrylates may be linear, branched or cyclic. Moreover, 1-18 are preferable, as for carbon number of the alkyl group of another alkyl (meth) acrylate, 1-8 are more preferable, and 1-4 are still more preferable.

  Examples of other alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, and n-octyl ( (Meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl ( Examples include meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.

  From the viewpoint of obtaining sufficient adhesive strength when the pressure-sensitive adhesive layer is formed, other alkyl (meth) acrylates include methyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. At least one selected from the group consisting of n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is more preferable.

  The content of the structural unit derived from the other alkyl (meth) acrylate in the (meth) acrylic polymer used in the present invention is preferably 35% by mass or more based on the total structural units. Thereby, the wettability to a to-be-adhered body rises by the heating of an adhesive layer, and there exists a tendency for the adhesive force of an adhesive layer to rise.

  The content of other alkyl (meth) acrylates in the (meth) acrylic polymer used in the present invention is from the viewpoint of increasing wettability to the adherend and increasing the adhesive strength of the pressure-sensitive adhesive layer, with respect to all structural units. 35 mass%-70 mass% is preferable, 50 mass%-65 mass% is more preferable, 55 mass%-63 mass% is still more preferable.

The (meth) acrylic polymer used in the present invention is a structural unit derived from tert-butyl (meth) acrylate, a structural unit derived from a monomer having a carboxy group, and a range in which the effects of the present invention are exhibited. Other structural units other than the structural units derived from other alkyl (meth) acrylates (hereinafter also referred to as “other structural units”) may be included.
The monomer constituting the other structural unit is not particularly limited as long as it can be copolymerized with tert-butyl (meth) acrylate and a monomer having a carboxy group, and can be appropriately selected according to the purpose.

  As other monomers constituting the structural unit, monomers having a functional group such as a hydroxyl group, an alkylene oxide group, a glycidyl group, an amide group, an N-substituted amide group, a tertiary amino group, a polyfunctional acrylic monomer, an aromatic Examples thereof include a monovinyl monomer, a vinyl cyanide monomer, a vinyl carboxylate monomer, and a (meth) acrylic monomer having an aromatic ring.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 6-hydroxyhexyl ( And (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and 3-methyl-3-hydroxybutyl (meth) acrylate.

  Examples of the monomer having an alkylene oxide group include methoxyethyl (meth) acrylate, 2- (ethoxyethoxy) ethyl acrylate, polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, Examples include polypropylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) acrylate.

  As monomers having a glycidyl group, glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meth) allyl ether, 3,4-epoxycyclohexyl Examples include (meth) allyl ether.

  Examples of the monomer having an amide group or an N-substituted amide group include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meta ) Acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-tert-butylacrylamide, N-octylacrylamide, diacetone acrylamide and the like.

  Examples of the monomer having a tertiary amino group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropyl (meth) acrylamide.

  Polyfunctional acrylic monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, caprolactone Modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (meth) acryloxyethyl isocyanurate, tricyclodecane dimethanol (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, ethylene oxide Modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane di (meth) acrylate, trimethylo Tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, diglycerol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate.

Examples of the aromatic monovinyl monomer include styrene, α-methylstyrene, tert-butylstyrene, p-chlorostyrene, chloromethylstyrene, vinyltoluene, and vinylpyridine.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile.
Examples of the vinyl carboxylate monomer include vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate (trade name, vinyl neodecanoate).

  Examples of the (meth) acrylic monomer having an aromatic ring include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide (EO) -modified cresol (meth) acrylate, and ethylene oxide. (EO) modified nonylphenol (meth) acrylate, hydroxyethylated β-naphthol acrylate, and biphenyl (meth) acrylate.

The content rate of the (meth) acrylic-type polymer used by this invention in an adhesive composition can be suitably selected according to the objective. The content of the (meth) acrylic polymer is preferably 60% by mass to 77% by mass and more preferably 64% by mass to 75% by mass with respect to the total solid content of the adhesive composition from the viewpoint of adhesive strength. 66 mass% to 72 mass% is more preferable.
In addition, solid content total mass means the total mass of the residue remove | excluding volatile components, such as a solvent, from an adhesive composition.

There is no restriction | limiting in particular in the weight average molecular weight (Mw) of the (meth) acrylic-type polymer used by this invention, From a viewpoint of improving an external appearance and adhesive force, it is preferable that it is 100,000-2 million, 200,000-1,500,000. It is more preferable that it is 500,000 to 1,200,000.
The weight average molecular weight can be adjusted by the polymerization reaction temperature, time, the amount of organic solvent, and the like.

The weight average molecular weight (Mw) of the (meth) acrylic polymer is a value measured by the following method.
(Measurement method of weight average molecular weight (Mw))
It measures according to following (1)-(3).
(1) A solution of (meth) acrylic polymer is applied to release paper and dried at 100 ° C. for 1 minute to obtain a film-like (meth) acrylic polymer.
(2) The film-like (meth) acrylic polymer obtained in (1) is dissolved in tetrahydrofuran so that the solid content is 0.2% by mass.
(3) The weight average molecular weight (Mw) of the (meth) acrylic polymer is measured as a standard polystyrene conversion value using gel permeation chromatography (GPC) under the following conditions.
(conditions)
GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: TSK-GEL GMHXL (manufactured by Tosoh Corporation) 4 used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.6 ml / min
Column temperature: 40 ° C

  The glass transition temperature (Tg) of the (meth) acrylic polymer used in the present invention is from −40 ° C. to −5 from the viewpoint of increasing the adhesive strength when used as an adhesive layer and keeping the tack after heating and cooling low. It is preferable that it is ° C, and it is more preferable that it is -35 ° C--20 ° C.

  The glass transition temperature (Tg) of the (meth) acrylic polymer is a molar average glass transition temperature obtained by calculation of the following formula.

_Wherein, Tg _1, Tg 2, ..... and Tg _n are the monomers 1, monomer 2, a glass transition represented by ----- and monomer n absolute temperature of the respective homopolymers (K) Temperature. m ₁ , m ₂ ,... and _mn are the mole fractions of the respective monomer components.

  The “glass transition temperature represented by the absolute temperature (K) of the homopolymer” refers to the glass transition temperature represented by the absolute temperature (K) of the homopolymer produced by polymerizing the monomer alone. . The glass transition temperature of the homopolymer was determined by using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Inc., EXSTAR6000), measuring sample 10 mg, heating rate 10 ° C. / The measurement is performed under the conditions of minutes, and the inflection point of the obtained DSC curve is defined as the glass transition temperature of the homopolymer.

Typical monomer “glass transition temperature expressed by Celsius temperature (° C.) of homopolymer” is 5 ° C. for methyl acrylate, −27 ° C. for ethyl acrylate, and −57 ° C. for n-butyl acrylate. 2-ethylhexyl acrylate is -76 ° C, 2-hydroxyethyl acrylate is -15 ° C, 4-hydroxybutyl acrylate is -39 ° C, tert-butyl acrylate is 41 ° C, tert- Butyl methacrylate is 107 ° C, vinyl acetate is 33 ° C, and acrylic acid is 163 ° C. For example, by using these typical monomers, the above-mentioned glass transition temperature can be appropriately adjusted.
The absolute temperature (K) can be converted into the Celsius temperature (° C.) by subtracting 273 from the absolute temperature (K), and the Celsius temperature (° C.) can be converted into the absolute temperature (° C.) by adding 273 to the Celsius temperature (° C.). K) can be converted.

  The method for producing the (meth) acrylic polymer used in the present invention is not particularly limited. The (meth) acrylic polymer used in the present invention can be produced, for example, by polymerizing monomers by a method such as solution polymerization, emulsion polymerization or suspension polymerization. In preparing the pressure-sensitive adhesive composition of the present invention after production, solution polymerization is preferable because the treatment process can be performed relatively easily and in a short time.

  In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent to be used as needed are generally charged in a polymerization tank and are stirred for several hours in a nitrogen stream or at the reflux temperature of the organic solvent. A method such as heating reaction can be used.

  Examples of the organic solvent used in the polymerization reaction of the (meth) acrylic polymer include aromatic hydrocarbon compounds, aliphatic or alicyclic hydrocarbon compounds, ester compounds, ketone compounds, glycol ether compounds, and alcohol compounds. Each of these organic solvents may be used alone or in combination of two or more.

  More specifically, examples of the organic solvent used in the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and Aromatic hydrocarbon-based organic solvents represented by aromatic naphtha, n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and aliphatic represented by turpentine oil To hydrocarbon-based or alicyclic hydrocarbon-based organic solvents, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate Representative ester organic solvents, acetone, methyl ethyl ketone, methyl-isobutyl ketone Ketone organic solvents typified by isophorone, cyclohexanone, and methylcyclohexanone, glycols typified by ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether Examples include ether organic solvents and alcohol organic solvents represented by methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol, and tert-butyl alcohol. .

  Moreover, as a polymerization initiator, the organic peroxide and azo compound which can be used with a normal polymerization method are mentioned, for example.

[Crosslinking agent]
Content of the crosslinking agent in the adhesive composition of this invention is less than 10 mass parts with respect to 100 mass parts of (meth) acrylic-type polymers.

  The crosslinking agent is not particularly limited as long as it can crosslink the (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention, and examples thereof include an epoxy compound, an isocyanate compound, an aziridine compound, and a metal chelate compound. Among them, an epoxy compound or an isocyanate compound is preferable. A crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

  Examples of the epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether, 2,2-dibromo Neopentyl glycol diglycidyl A , Trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate, tris (glycidoxyethyl) isocyanurate, 1 , 3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-1,3-benzenedi (methanamine). These epoxy compounds may be used individually by 1 type, and may use 2 or more types together.

Examples of the isocyanate compound include xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, aromatic polyisocyanate compounds represented by tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenation of the above-described aromatic polyisocyanate compound. Chain or cyclic aliphatic polyisocyanate compounds represented by products, burettes, dimers, trimers or pentamers of these polyisocyanate compounds, these polyisocyanate compounds and polyols such as trimethylolpropane Examples include adducts with compounds.
These isocyanate compounds may be used individually by 1 type, and may use 2 or more types together.

  Among these, as the isocyanate compound, tolylene diisocyanate, tolylene diisocyanate dimer, adduct of tolylene diisocyanate and polyol, tolylene diisocyanate trimer or pentamer isocyanurate, tolylene diisocyanate Tolylene diisocyanate compounds derived from various tolylene diisocyanates such as burettes are preferred. Furthermore, from the viewpoint of excellent reactivity and the ability to increase the crosslinking density, and from the viewpoint of excellent compatibility with the (meth) acrylic polymer, tolylene diisocyanate or an adduct of tolylene diisocyanate and a polyol is preferable, and in particular, crosslinking. From the viewpoint of suppressing gelation at the time, tolylene diisocyanate or an adduct of tolylene diisocyanate and trimethylolpropane is particularly preferable.

  A commercially available product may be used as the epoxy compound. As a commercial item, what is marketed by the brand name of "TETRAD-X" and "TETRAD-C" by Mitsubishi Gas Chemical Co., Ltd. can be used conveniently, for example.

  A commercially available product may be used as the isocyanate compound. Examples of commercially available products include “Coronate HX”, “Coronate HL-S”, “Coronate L”, “Coronate 2031”, “Coronate 2030”, “Coronate 2037”, “Coronate 2234” manufactured by Tosoh Corporation. "Coronate 2785", "Aquanate 200" and "Aquanate 210", "Sumijoule N3300", "Desmodur N3400" and "Sumijoule N-75" manufactured by Covestro, "Duranate" manufactured by Asahi Kasei Chemicals Corporation “E-405-80T”, “Duranate 24A-100”, and “Duranate TSE-100”, and “Takenate D-110N”, “Takenate D-120N”, “Takenate M-631N” manufactured by Mitsui Chemicals, Inc. , And products of "MT-Olestar NP1200" It can be suitably used those commercially available by.

The pressure-sensitive adhesive composition of the present invention may not contain a crosslinking agent, but preferably contains 0.01 parts by mass or more of the crosslinking agent with respect to 100 parts by mass of the (meth) acrylic polymer. By including 0.01 parts by mass or more of a crosslinking agent, when the (meth) acrylic polymer contains a crosslinkable functional group such as a carboxy group, the crosslinking reaction between the (meth) acrylic polymer and the crosslinking agent is sufficient. Therefore, the generation of wrinkles after heating and cooling tends to be suppressed, and the appearance tends to be excellent.
From the above viewpoint, the content of the crosslinking agent in the pressure-sensitive adhesive composition of the present invention is preferably 0.05 parts by mass or more, and 0.1 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer. Is more preferable.
In the case where the pressure-sensitive adhesive composition contains a crosslinking agent, the (meth) acrylic polymer includes a structural unit derived from a monomer having a carboxy group from the viewpoint of imparting cohesive force to the pressure-sensitive adhesive layer and improving the appearance. It is preferable.

  Moreover, content of the crosslinking agent in the adhesive composition of this invention is less than 10 mass parts with respect to 100 mass parts of (meth) acrylic-type polymers. When the content of the crosslinking agent in the pressure-sensitive adhesive composition is 10 parts by mass or more, when the (meth) acrylic polymer contains a crosslinkable functional group such as a carboxy group, the (meth) acrylic polymer and the crosslinking agent The crosslinking reaction proceeds excessively, the pressure-sensitive adhesive layer becomes too hard, and it becomes difficult to impart sufficient pressure-sensitive adhesive force to the pressure-sensitive adhesive layer. In addition, when the (meth) acrylic polymer does not contain a crosslinkable reactive group such as a carboxy group, the amount of the crosslinking agent becomes excessive, for example, a gas is generated due to a condensation reaction between the crosslinking agents, and the appearance is increased. There is a tendency to be inferior.

  The cross-linking reaction between the (meth) acrylic polymer and the cross-linking agent is allowed to proceed moderately to give the pressure-sensitive adhesive layer adhesive force, and improve the wettability during heating and suppress foaming from the adherend. From the viewpoint of improving the appearance, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.05 parts by mass to 8.0 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, it is 0.5 mass part-8.0 mass part.

When an isocyanate compound is included as a crosslinking agent, the content of the isocyanate compound is preferably 0.1 parts by mass to 8.0 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer, and 1.0 parts by mass to 7 parts by mass. 0.0 part by mass is more preferable, and 3.0 parts by mass to 6.0 parts by mass is even more preferable.
When an epoxy compound is included as a crosslinking agent, the content of the epoxy compound is preferably 0.1 part by mass to 0.5 part by mass with respect to 100 parts by mass of the (meth) acrylic polymer, and 0.2 part by mass to 0 part by mass. More preferably, 4 parts by mass.
If it is within the above range, the generation of wrinkles during heating and cooling tends to be suppressed, and the appearance tends to be excellent.

<Tackifying resin>
The pressure-sensitive adhesive composition of the present invention contains 30 parts by mass to 50 parts by mass of a tackifying resin with respect to 100 parts by mass of the (meth) acrylic polymer.
The softening point of the tackifier resin can be measured by the ring and ball method.

  Examples of tackifying resins include natural resin systems and synthetic resin systems. Since it is easy to balance the compatibility with the (meth) acrylic polymer, a natural resin-based tackifier resin is preferable, and at least one selected from a terpene resin and a rosin resin is preferable.

  Examples of the terpene resin include an unmodified terpene resin, a terpene phenol resin, an aromatic modified terpene resin, and a hydrogenated terpene resin, and among them, a terpene phenol resin is preferable.

  Examples of the terpene phenol resin include a copolymer of a terpene and a phenol compound. For example, monocyclic monoterpenes represented by α-pinene, β-pinene, and dipentene (limonene), and phenol and cresol. And a copolymer with a phenol compound typified by bisphenol A.

  Examples of the rosin resin include rosin, hydrogenated rosin, disproportionated rosin, and esterified rosin. Among these, esterified rosin is preferable.

  These terpene resins and rosin resins may be used alone or in combination of two or more.

  Commercial products may be used as the terpene resin and rosin resin. Examples of commercially available terpene resins include “YS Resin TO-105”, “YS Polystar U130”, “YS Polystar T130”, “YS Polystar TH130”, “YS Polystar T145”, “YS” manufactured by Yashara Chemical Co., Ltd. “Polystar T160”, “YS Polyster S145”, “YS Polystar G150”, and “YS Polystar K140”, and “Tamanor 803L” and “Tamanor 901” manufactured by Arakawa Chemical Industries, Ltd. A thing can be used conveniently. Examples of commercially available rosin resins include “Neotor 160”, “Harry Star S”, “Harry Star DS-90S”, “Harry Star DS-110S” manufactured by Harima Chemical Co., Ltd., and Arakawa Chemical Industries Ltd. What is marketed with the brand name of "Pencel D-125" made from a company can be used conveniently.

  As a softening point of tackifying resin, 70 to 130 degreeC is preferable. When the softening point is 70 ° C. or higher, an increase in tack in the pressure-sensitive adhesive layer after heating and cooling tends to be suppressed. When the softening point is 130 ° C. or lower, the wettability to the adherend is increased by heating the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer tends to be increased.

  From the above viewpoint, the softening point of the tackifier resin is preferably 70 ° C to 125 ° C, more preferably 75 ° C to 115 ° C, and still more preferably 80 ° C to 110 ° C.

  The pressure-sensitive adhesive composition of the present invention contains 30 to 50 parts by mass of a tackifier resin with respect to 100 parts by mass of a (meth) acrylic polymer. For this reason, it is estimated that the tackifying resin is easily localized by the surface layer of the pressure-sensitive adhesive layer during heating. Thereby, even in the room temperature environment after cooling, the tackifier resin is localized on the surface layer of the pressure-sensitive adhesive layer, and the increase in tack is suppressed.

Moreover, when the pressure-sensitive adhesive composition of the present invention contains more than 50 parts by mass of the tackifying resin with respect to 100 parts by mass of the (meth) acrylic polymer, the tackifying resin excessively bleeds out from the surface of the pressure-sensitive adhesive layer. Therefore, there is a tendency that it is difficult to give sufficient adhesive strength. Moreover, when content of tackifying resin is less than 30 mass parts with respect to 100 mass parts of (meth) acrylic-type polymers, it will become difficult to fully suppress the raise of the tack after heating and cooling.
From the above viewpoint, the content of the tackifier resin is preferably 35 parts by mass to 45 parts by mass, and more preferably 37 parts by mass to 43 parts by mass.

[Other ingredients]
In addition to the (meth) acrylic polymer, the crosslinking agent and the tackifier resin, the pressure-sensitive adhesive composition of the present invention includes a crosslinking catalyst, a silane coupling agent, an organic solvent, a weather resistance stabilizer, a plasticizer, Softeners, peeling aids, dyes, pigments, inorganic fillers, surfactants, antioxidants, metal corrosion inhibitors, UV absorbers, light stabilizers typified by hindered amine compounds, and the like may be included as appropriate. .

-Gel fraction-
In the pressure-sensitive adhesive composition of the present invention, the gel fraction after crosslinking is preferably less than 50% by mass. When the gel fraction after cross-linking is less than 50% by mass, the cross-linked structure does not increase too much, it becomes possible to impart adhesive force to the pressure-sensitive adhesive layer, reduce tack after heating and cooling, and the polarity is There is a tendency that sufficient adhesive force can be obtained even on a low adherend.
From the above viewpoint, the gel fraction after crosslinking is more preferably 45% by mass or less, and still more preferably 40% by mass or less.
The gel fraction after crosslinking is preferably 0.5% by mass or more, and more preferably 1% by mass or more from the viewpoint of improving the appearance by suppressing generation of wrinkles and foaming.
In addition, when performing curing, it is preferable that the gel fraction after curing is the said range.
Moreover, the gel fraction in case the adhesive composition of this invention does not contain a crosslinking agent is a value measured by the following method, after apply | coating an adhesive composition to a peeling film or a base material and drying.

The “gel fraction” after crosslinking in the pressure-sensitive adhesive composition is a value measured according to the following procedures (1) to (17).
(1) The pressure-sensitive adhesive composition was coated on a 100 μm-thick PET film separator (release paper), air-dried at room temperature for 30 minutes, and then dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer. A sticky adhesive layer is obtained.
(2) The obtained pressure-sensitive adhesive layer with a separator is cured for 7 days under conditions of 23 ° C. and a relative humidity of 65%. Thereafter, the pressure-sensitive adhesive layer with a separator is cut into a size of 75 mm × 75 mm. The weight of the pressure-sensitive adhesive layer of the cut sample is approximately 0.2 g.

(3) A metal wire mesh of 250 mesh (wire diameter 0.03 mm, mesh opening 72 μm, made of stainless steel) is prepared, and the metal wire mesh is cut into a size of 100 mm × 100 mm.
(4) The metal wire mesh is degreased with ethyl acetate and then dried. The metal wire mesh after degreasing and drying is stored in a desiccator. Also, the end of the metal wire mesh is removed in advance because it causes measurement errors.
(5) Measure the mass of the metal wire mesh accurately. Let this mass be A.

(6) After sticking the separator-attached pressure-sensitive adhesive layer (2) cut out to a size of 75 mm × 75 mm in the center of the metal wire mesh, the PET film separator is peeled off from the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer is attached to the metal wire mesh so that the pressure-sensitive adhesive layer is positioned in the plane after the metal wire mesh is folded by the following steps (7) to (9).
(7) The metal wire mesh is folded in half from the back side to the near side with the surface on which the film-like adhesive layer is attached as the inside.
(8) Fold the front third of the metal wire mesh (having two ends on the front side) folded in half, and then fold the back third in front (100 mm in the vertical direction) Folded to one-sixth of the width and not folded in the horizontal direction).
(9) Fold the wire mesh to the right at the one-third portion from the left and similarly fold to the left at the one-third portion from the right. This is designated as Sample 1. In the sample 1, the vertical direction is folded by 1/6 and the horizontal direction is folded by 1/3 because of the size of the original metal wire mesh.
(10) The mass of the sample 1 is accurately measured. Let this mass be B.

(11) The sample 1 is fastened with a stapler so as not to open the crease. This is designated as Sample 2. The mass of sample 2 is measured. Let this mass be C.
(12) Two samples 2 for gel fraction measurement are prepared for one type of pressure-sensitive adhesive composition.

(13) Put sample 2 in a glass bottle containing 80 g of ethyl acetate and cover.
(14) The glass bottle containing the sample 2 is left for 3 days at 23 ° C. and a relative humidity of 65%.
(15) Remove Sample 2 from the glass bottle and simply wash with ethyl acetate.
(16) After the sample 2 is dried at 120 ° C. for 24 hours, the mass is accurately measured. This is D.

(17) Calculate the gel fraction by the following formula.
Gel fraction [% by mass] = (D− (A + (CB))) / (B−A) × 100

[Usage]
The pressure-sensitive adhesive composition of the present invention is used for sticking a decorative film to an adherend.
Examples of the method for attaching the decorative film to the adherend include a vacuum forming method, a pressure forming method, and a hot-high pressure forming method. Among these, a vacuum forming method is preferable as a method for attaching the decorative film to the adherend.

The adherend is not particularly limited, and examples thereof include plate materials such as flat plates and curved plates, three-dimensional shaped articles, and molded products such as films. Among these, a three-dimensional article is preferable as the adherend. The material for forming the adherend is not particularly limited, and examples thereof include ABS resin, polycarbonate resin, polyester resin, PP resin, and polyethylene (PE) resin.
Among them, the pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer that has a low tack after heating and cooling and has a high adhesion to an adherend with low polarity. It can be suitably used when adhering to an adherend formed from a resin having a low polarity such as a resin. In addition, since the pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer with low tack after heating and cooling and high adhesion to an adherend with low polarity, a decorative film is generally applied. It can be suitably used when sticking to a three-dimensional article that is difficult to wear.

<Adhesive sheet>
The present invention may be a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive sheet of the present invention may be a non-base material-type pressure-sensitive adhesive sheet having no base material, or a base material-type pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one side of the base material.

  In the pressure-sensitive adhesive sheet of the present invention, the thickness of the pressure-sensitive adhesive layer is not particularly limited, and can be appropriately selected depending on the application and required performance. As a thickness of an adhesive layer, the range of 1 micrometer-100 micrometers is mentioned, for example.

  The exposed pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention may be protected by a release film. The release film is not particularly limited as long as it can be easily peeled off from the pressure-sensitive adhesive layer, and examples thereof include a resin film that has been subjected to easy release treatment on at least one side using a release treatment agent. As a resin film, the polyester film represented by the polyethylene terephthalate film is mentioned, for example. Examples of the release treatment agent include a fluorine-based resin, paraffin wax, silicone, and a long-chain alkyl group compound. The release film protects the surface of the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet is practically used, and is peeled off during use.

  The pressure-sensitive adhesive sheet of the present invention can be produced, for example, by forming a pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition of the present invention to a release film or a substrate and curing it after drying for a certain period. The curing conditions can be 1 to 10 days under an environment of 23 ° C. and 50% RH (relative humidity), for example. By curing the pressure-sensitive adhesive layer, the (meth) acrylic polymer can be sufficiently crosslinked by the crosslinking agent.

  The non-base type pressure-sensitive adhesive sheet is formed by, for example, applying a pressure-sensitive adhesive composition to the release-treated surface of a release film, drying it to form a layer of the pressure-sensitive adhesive composition, and contacting the release film of the obtained layer. It can be produced by a method in which another release film is stacked on the exposed surface so that the release treatment surface is in contact with the exposed surface, and is cured to form an adhesive layer.

  The substrate-type pressure-sensitive adhesive sheet may be produced by a method in which the pressure-sensitive adhesive composition is applied to a substrate, or may be produced by a method in which the pressure-sensitive adhesive composition is applied to a release film. As such a method, for example, the pressure-sensitive adhesive composition is applied to the release-treated surface of the release film and dried to form a layer of the pressure-sensitive adhesive composition, and the exposed layer that is not in contact with the release film is exposed. The method of bonding a base material to a surface and curing and forming an adhesive layer is mentioned.

  Examples of the method for applying the pressure-sensitive adhesive composition to the release film or the substrate include known methods using a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, etc. It is done.

<Decorative film>
Examples of the substrate-type pressure-sensitive adhesive sheet include a decorative film having at least a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and a base material. As a base material in a decorative film, for example, a resin layer formed from a thermoplastic resin may be used, and among them, it is preferable to include a vinyl chloride resin, an ABS resin, a PP resin, or an acrylic resin. A base material formed using a vinyl chloride resin, an ABS resin, a PP resin, or an acrylic resin is required to produce a decorative molded product by a vacuum forming method. Excellent vacuum forming processability such as shape followability.

  The base material in the decorative film is positioned in, for example, the outermost layer of the decorative molded product after the decorative film is decorated on the molded body, and functions as a protective layer for the decorative molded product. By forming the base material from vinyl chloride resin, ABS resin, PP resin, or acrylic resin, it becomes a decorative molded product having excellent durability such as wear resistance, chemical resistance, and weather resistance.

The base material in the decorative film may be colorless or colored. In order to color the substrate, a known colorant may be added to the resin.
Further, the substrate in the decorative film may be transparent, translucent, or opaque.

Usually, the thickness of the substrate is preferably 25 μm to 300 μm, more preferably 50 μm to
200 μm. When the thickness of the base material is within the above range, when the decorative molded product is manufactured by the vacuum forming method, the processability, the shape followability, and the handleability are improved.

  The decorative film of the present invention is not particularly limited, and may have a decorative layer between the base material and the pressure-sensitive adhesive layer. A decoration layer is a layer provided in order to provide designability to a decoration film, and is a pattern layer expressing a pattern, a character, a pattern picture, etc.

<Decorated molded products>
The decorative molded product of this invention has a molded object and the said decorative film arrange | positioned on a molded object. More specifically, a molded body, a pressure-sensitive adhesive layer, and, if necessary, a decorative layer and a base material layer are laminated in this order.
The decorative molded product of the present invention can be obtained by laminating the decorative film of the present invention on a molded body by a vacuum forming method or a pressure forming method (preferably a vacuum forming method).

The molded body is not particularly limited as long as the decorative film of the present invention can be attached, and examples thereof include plate materials such as flat plates and curved plates, three-dimensional shaped articles, and molded products such as films. Among these, a three-dimensional article is preferable as the molded body.
The material of the molded body is not particularly limited, and examples thereof include ABS resin, polycarbonate resin, polyester resin, PP resin, and PE resin.
Among these, PP resin, PE resin and the like are preferable as the material of the molded body.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Production of (meth) acrylic polymer]
<Production Example 1>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a sequential dropping device and a thermometer, 57 parts by mass of n-butyl acrylate (BA), 42 parts by mass of tert-butyl acrylate (tBA), acrylic acid (AA ) 1 part by mass and 75 parts by mass of ethyl acetate (EAc) were added, and the air in the reaction vessel was replaced with nitrogen gas. Thereafter, the temperature of the contents of the reaction vessel was raised to 70 ° C. in a nitrogen atmosphere under stirring. Thereafter, a solution in which 0.02 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) (ABN-V), which is a polymerization initiator, was dissolved in 120 parts by mass of ethyl acetate (EAc) over 4 hours. Then, the solution was added dropwise and reacted for another 2 hours. After completion of the reaction, the reaction mixture was diluted with methyl ethyl ketone to obtain a solution of a (meth) acrylic polymer having a solid content of about 20% by mass.
The obtained (meth) acrylic polymer had a glass transition temperature (Tg) of −23 ° C., a weight average molecular weight (Mw) of 1,000,000, and a gel fraction of 22 mass%. Table 1 shows the monomer composition in Production Example 1.
The glass transition temperature (Tg), the weight average molecular weight (Mw), and the gel fraction (mass%) were measured and calculated by the methods described above.

<Production Examples 2-14>
A (meth) acrylic polymer solution was obtained in the same manner as in Production Example 1 except that the monomer composition shown in Table 1 below was used, and the weight average molecular weight was adjusted by changing the amounts of the organic solvent and the polymerization initiator.
Table 1 shows the monomer composition, glass transition temperature (Tg), weight average molecular weight (Mw), and gel fraction (mass%) of the (meth) acrylic polymer produced in Production Examples 2 to 14.
The glass transition temperature (Tg), the weight average molecular weight (Mw), and the gel fraction (mass%) were measured and calculated by the methods described above.

<Preparation of pressure-sensitive adhesive composition>
Example 1
100 parts by mass of the solution of the (meth) acrylic polymer of Production Example 1 obtained above as a solid content and 6.7 parts by mass of coronate L (manufactured by Tosoh Corporation, trimethylolpropane adduct of tolylene diisocyanate) ( 5 parts by mass as an active ingredient) and Hariestar DS-90S (Harima Kasei Co., Ltd., softening point 90 ° C., active ingredient 100%), which is a rosin-glycerin resin as a tackifier resin, is 50% by mass with ethyl acetate. A pressure-sensitive adhesive composition was obtained by sufficiently stirring and mixing 80 parts by weight (30 parts by weight as an active ingredient) of a solution diluted in a% solution.
Table 1 shows the composition of the pressure-sensitive adhesive composition prepared in Example 1.

<Production of test film>
Using the pressure-sensitive adhesive composition obtained in Example 1, a test film was produced as follows.
First, the pressure-sensitive adhesive composition is fluted so that the thickness after drying is about 40 μm on the release-treated surface of a polyethylene terephthalate (PET) film (thickness: 100 μm) that has been subjected to a release treatment on one side. It was applied and dried at 100 ° C. for 2 minutes.
Thereafter, the PET film coated with the pressure-sensitive adhesive composition and the vinyl chloride film (thickness 150 μm) were superposed so that the coated surface of the pressure-sensitive adhesive composition solution was in contact with the vinyl chloride film to obtain a laminate. After this laminate was pressed and bonded through a pair of pressure nip rolls, it was cured for 7 days under conditions of 23 ° C. and 50% RH, and a test film (PET film / adhesive layer / vinyl chloride film) was obtained. Produced.

[Evaluation]
<Adhesive strength>
The produced test film was cut to 25 mm × 150 mm, and then the PET film was peeled off, superimposed on a 1 mm-thick PP plate, which was an adherend, and pasted once with a 2 kg roller. Then, it was put into a dryer at 110 ° C. for 10 minutes and heated. Next, the test film was taken out from the dryer, allowed to cool for 30 minutes under conditions of 23 ° C. and 50% RH, and then the adhesion at a peeling rate of 100 mm / min and 180 ° peeling was measured.
The adhesive strength after heating and cooling was evaluated according to the following evaluation criteria, and the results are shown in Table 1.
If the evaluation results are A to C, there is no practical problem, but B or more is preferable, and A is more preferable. The results of measuring the adhesive strength are shown in Table 1.
(Evaluation criteria)
A: 30 N / 25 mm or more B: 15 N / 25 mm or more and less than 30 N / 25 mm C: 10 N / 25 mm or more and less than 15 N / 25 mm D: Less than 10 N / 25 mm

<Tack after heating and cooling>
The following probe tack test was conducted using the test film prepared above.
First, the produced test film was cut into 25 mm × 150 mm, put into a dryer at 110 ° C. for 1 hour, and heated. Next, the test film was taken out of the dryer and allowed to cool for 30 minutes under conditions of 25 ° C. and 50% RH, and then the PET film was peeled off. The tack of the pressure-sensitive adhesive layer of the test film was measured with a probe size 5φ, a contact time of 0.1 second, an indentation load of 200 gf, and a temperature of 25 ° C. and 50% RH, using a tacking tester (Model TAC-1000) manufactured by Reska Co., Ltd. The tack after heating and cooling was measured under the conditions.
Tack after heating and cooling was evaluated according to the following evaluation criteria, and the results are shown in Table 1.
If the evaluation results are A to C, there is no practical problem, but B or more is preferable, and A is more preferable.
(Evaluation criteria)
A: Less than 100 gf / 5φ B: 100 gf / 5φ or more and less than 200 gf / 5φ C: 200 gf / 5φ or more and less than 400 gf / 5φ D: 400 gf / 5φ or more

<Appearance>
The prepared test film was cut to 50 mm × 75 mm, and then the PET film was peeled off, and was superimposed on a 2 mm-thick PP plate, which was an adherend, and pasted once with a 2 kg roller.
Then, it was put into a dryer at 110 ° C. for 1 hour and heated. Subsequently, it was taken out from the dryer, and the appearance of the vinyl chloride film surface was visually confirmed.
The appearance was evaluated according to the following evaluation criteria, and the results are shown in Table 1.
(Evaluation criteria)
A: Wrinkles and foaming are not seen, and the appearance is very good.
B: Appearance is good because wrinkles and foaming are partially observed.
C: Wrinkles and foaming are observed on the entire surface.

(Examples 2 to 21)
In Examples 2 to 21, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive composition shown in Table 1 below was used. Using the prepared pressure-sensitive adhesive composition, a test film was produced in the same manner as in Example 1. Each test film was evaluated in the same manner as in Example 1. The results are shown in Table 1.
In addition, the compounding quantity shown in Table 1 is a solid content conversion value or an active ingredient conversion value.

(Comparative Examples 1-9)
In Comparative Examples 1 to 9, pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive composition shown in Table 1 below was used. Using the prepared pressure-sensitive adhesive composition, a test film was produced in the same manner as in Example 1. Each test film was evaluated in the same manner as in Example 1. The results are shown in Table 1.
In addition, the compounding quantity shown in Table 1 is a solid content conversion value or an active ingredient conversion value.

  Abbreviations in Table 1 are as follows. In addition, the mass part number of Table 1 is a conversion value of solid content or an active ingredient. “-” In Table 1 indicates that the corresponding component is not included.

TBA: tert-butyl acrylate BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate AA: acrylic acid Coronate L: isocyanate compound (manufactured by Tosoh Corporation, adduct form of tolylene diisocyanate and trimethylolpropane)
TETRAD-X: epoxy compound (Mitsubishi Gas Chemical Co., Ltd., N, N, N ′, N′-tetraglycidyl-1,3-benzenedi (methanamine))
DS-90S: Rosin-based tackifying resin having a softening point of 90 ° C. (trade name: Harrier Star DS-90S, manufactured by Harima Chemical Co., Ltd.)
・ Hari Star S: Rosin-based tackifying resin with a softening point of 70 ° C. (Harima Kasei Co., Ltd., trade name: Harri Star S)
DS-110S: Rosin-based tackifying resin having a softening point of 110 ° C. (manufactured by Harima Chemicals Co., Ltd., trade name: Harrier Star DS-110S)
D-125: Rosin-based tackifying resin having a softening point of 125 ° C. (Arakawa Chemical Industries, trade name: Pencel D-125)
TO-105: Aromatically modified terpene tackifying resin having a softening point of 105 ° C. (trade name: YS Resin TO-105, manufactured by Yashara Chemical Co., Ltd.)

[result]
The content of the structural unit derived from tert-butyl (meth) acrylate is 25% by mass to 65% by mass with respect to all the structural units, and the content of the structural unit derived from the monomer having a carboxy group is the total content. Adhesives of Examples 1 to 21, comprising 100 parts by weight of (meth) acrylic polymer, 30 parts by weight to 50 parts by weight of tackifier resin, and less than 10 parts by weight of a crosslinking agent with respect to the unit of 8% by weight or less. The decorative film having the pressure-sensitive adhesive layer formed from the adhesive composition was excellent in adhesive strength to adherends having low polarity, and the tack after heating and cooling was kept low.
In particular, the decorative film having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive compositions of Examples 2, 3, 5, 7, 9 to 11 and 15 to 21 was more excellent for adherends having low polarity. It had adhesive force and the tack after heating and cooling was kept lower. Among these, the decorative film which has the adhesive layer formed from the adhesive composition of Examples 2, 3, 5, 7, 9-11, and 17-21 was excellent in addition to the external appearance.

On the other hand, the content rate of the structural unit derived from the comparative example 1 and tert- butyl (meth) acrylate in which the content rate of tackifying resin is less than 30 mass parts with respect to 100 mass parts of (meth) acrylic-type polymers is all. Comparative Example 4 of less than 25% by mass with respect to the structural unit, which does not include a structural unit derived from tert-butyl (meth) acrylate, and is derived from n-butyl acrylate as a structural unit derived from alkyl (meth) acrylate In Comparative Example 6 containing only the above and Comparative Example 8 containing no structural unit derived from tert-butyl (meth) acrylate, both were poor in tack after heating and cooling.
Comparative Example 2 in which the content of the tackifying resin exceeds 50 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer, the content of the structural unit derived from the monomer having a carboxy group is 8 masses with respect to all the structural units. Comparative Example 3 in excess of%, Comparative Example 5 in which the content of structural units derived from tert-butyl (meth) acrylate exceeds 65% by mass with respect to all structural units, and the content of the crosslinking agent is (meth) acrylic In Comparative Example 9 exceeding 10 parts by mass with respect to 100 parts by mass of the polymer, all had poor adhesion to adherends with low polarity.
The comparative example 7 which does not contain tackifying resin was inferior in the adhesive force with respect to a to-be-adhered body with low polarity, and was inferior to the tack after heating and cooling.

  From the above, it can be seen that the decorative film having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention has a low tackiness after heating and cooling and has an adhesive force to an adherend having a low polarity. . Moreover, when the gel fraction exceeds 0 mass%, it turns out that the decoration film which has the adhesive layer formed from the adhesive composition of this invention is also a favorable result also about an external appearance.

Claims (9)

The content of the structural unit derived from tert-butyl (meth) acrylate is 25% by mass to 65% by mass with respect to all the structural units, and the content of the structural unit derived from the monomer having a carboxy group is the total content. 100 parts by weight of a (meth) acrylic polymer that is 8% by weight or less based on the unit;
A pressure-sensitive adhesive composition for a decorative film, comprising 30 parts by mass to 50 parts by mass of a tackifier resin, wherein the content of the crosslinking agent is less than 10 parts by mass.   The pressure-sensitive adhesive composition for a decorative film according to claim 1, wherein the tackifying resin has a softening point of 70C to 130C.   The pressure-sensitive adhesive composition for a decorative film according to claim 1 or 2, wherein the glass transition temperature of the (meth) acrylic polymer is -40 ° C to -5 ° C.   The content rate of the structural unit derived from the monomer which has a carboxy group in the said (meth) acrylic-type polymer is 0.05 mass% or more with respect to all the structural units, In any one of Claims 1-3. The pressure-sensitive adhesive composition for a decorative film as described.   The pressure-sensitive adhesive composition for a decorative film according to any one of claims 1 to 4, wherein the tackifying resin is at least one selected from terpene resins and rosin resins.   Content of the said crosslinking agent is 0.01 mass part or more with respect to 100 mass parts of said (meth) acrylic-type polymers, The adhesive for decorative films of any one of Claims 1-5. Composition.   The pressure-sensitive adhesive composition for a decorative film according to claim 6, wherein the gel fraction after crosslinking is less than 50% by mass.   The decorating film which has a base material and the adhesive layer formed from the adhesive composition for decorating films of any one of Claims 1-7.   The decorative molded product which has a molded object and the decorative film of Claim 8 arrange | positioned on the said molded object.