TWI776869B - surface protection film - Google Patents

Abstract

The present invention provides an optical surface protective film with low ultraviolet transmittance, suppressed hue change and excellent adhesion stability. The optical surface protective film of the present invention is characterized in that: it is formed by providing a base material formed of a polyester resin and an adhesive layer formed of an adhesive composition on one side of the base material; The b* value of the protective film is 2 or less, the transmittance of the above-mentioned surface protective film at a wavelength of 365 nm is 2% or less, and the adhesive force after the above-mentioned adhesive layer is attached to the glass and heated at 100°C for 30 minutes is relatively The change rate of the adhesive force before heating is less than ±30%.

Description

surface protection film

The present invention relates to an optical surface protection film. In particular, it is used to protect the surface of optical members (for example, polarizers, wavelength plates, retardation plates, optical compensation films, reflection sheets, brightness enhancement films, cover glass for displays, etc. for liquid crystal displays, etc.) On the other hand, a surface protection film for optics that protects a member that is prone to deterioration and the like from ultraviolet rays is useful.

The protective film generally has a structure in which an adhesive layer is provided on a film-like base material. The purpose of using this protective film is to adhere it to an optical member as an adherend through the above-mentioned adhesive layer, thereby protecting the optical member from surface damage or contamination during processing, transportation, inspection, and the like. For example, the panel of a liquid crystal display is formed by bonding optical members, such as a polarizing plate and a wave plate, to a liquid crystal cell via an adhesive bond layer (patent document 1).

As a protective film, an appearance inspection or the like may be performed in a state of being attached to an optical member or the like, and therefore it is required to prevent the color change (discoloration such as reddening) of the protective film over time.

Moreover, since the liquid crystal enclosed in the liquid crystal cell of the panel used for a liquid crystal display is deteriorated by ultraviolet rays, it is used by attaching a protective film having an ultraviolet absorption function to a member such as a polarizing plate attached to the liquid crystal cell.

In addition, in recent years, in the manufacture of cover glass for mobile terminals such as thin smartphones and tablets, resins that are hardened by active energy such as ultraviolet rays or heat are used for lamination work, but there are cases where no ultraviolet rays are used. A protective film containing an ultraviolet absorber is used in order to protect a member that is degraded by ultraviolet rays due to irradiation.

The protective film used will be peeled off at a stage when it is no longer needed. However, when the protective film attached to the cover glass used in thin smartphones, etc. is to be peeled off and removed, it is For the protective film with increased adhesive force, it is difficult to easily peel off and remove the protective film, and the cover glass may be damaged or the like. [Prior Art Literature] [Patent Literature]

[Patent Document 1]: Japanese Patent Laid-Open No. 2007-304425

[Problems to be Solved by Invention]

Therefore, the present inventors made diligent studies in view of the above-mentioned circumstances, and as a result, an object of the present invention is to provide a surface protective film for optics with low ultraviolet transmittance, suppressed hue change, and excellent adhesion stability. [Technical means to solve problems]

That is, the optical surface protective film of the present invention is characterized in that: it is formed by providing a substrate formed of a polyester resin and an adhesive layer formed of an adhesive composition on one side of the substrate; The b* value of the above-mentioned surface protective film is 2 or less, and the transmittance of the above-mentioned surface protective film at a wavelength of 365 nm is 2% or less. After the above-mentioned adhesive layer is attached to the glass, it is heated at 100°C for 30 minutes. The change rate of the force relative to the adhesive force before heating is ±30% or less.

In the optical surface protective film of this invention, it is preferable that the said adhesive composition contains an ultraviolet absorber.

In the optical surface protective film of this invention, it is preferable that the hydroxyl group in the molecule|numerator of the said ultraviolet absorber is 3 or less.

In the optical surface protective film of this invention, it is preferable that the said adhesive composition contains a (meth)acrylic-type polymer and/or a urethane-type polymer as a base polymer.

In the optical surface protective film of this invention, it is preferable that the said adhesive composition contains 0.1 weight part - 20 weight part of said ultraviolet absorbers with respect to 100 weight part of said base polymers.

It is preferable that the thickness of the said base material is 6-100 micrometers in the surface protective film for optics of this invention, and the thickness of the said adhesive bond layer is 1-30 micrometers.

By using a surface protective film having specific optical properties, the present invention is useful because it can obtain a surface protective film for optics with low transmittance of ultraviolet rays, suppressed hue change, and excellent adhesion stability.

Hereinafter, embodiments of the present invention will be described in detail.

<Overall structure of optical surface protective film> The optical surface protective film (hereinafter, sometimes simply referred to as "surface protective film") disclosed here is generally referred to as an adhesive tape, adhesive tape, adhesive film, etc. When the surface of the agent layer is protected by a separator, it is especially suitable for protecting the surface of optical parts (for example, optical parts used as components of liquid crystal display panels such as polarizers, wave plates, cover glass, etc.), inspection, and transportation. surface protective film. The adhesive layer in the above-mentioned surface protective film is typically formed continuously, but is not limited to this form. For example, it may be an adhesive layer formed in a regular or random pattern such as dots and stripes. In addition, the surface protective film disclosed here may be in a roll form, or a single sheet form may be sufficient as it.

<Substrate> The optical surface protective film of the present invention is characterized by having a substrate formed of a polyester-based resin. The above-mentioned base material formed of a polyester-based resin has preferable characteristics as a base material for a surface protective film, such as excellent optical properties and excellent dimensional stability.

Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, etc. having ester bonds can be preferably used as the above-mentioned polyester resins. The polyester-based polymer material (polyester resin) of the basic main skeleton is the resin material constituting the main resin component (the main component in the resin component, typically 50% by weight or more) as the above-mentioned base material. Examples of resin materials other than the above polyester-based resins include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; polyethylene, polypropylene, and polymers having a cyclic or norbornene structure. Olefin-based polymers such as olefins and ethylene-propylene copolymers; vinyl chloride-based polymers; and amide-based polymers such as nylon 6, nylon 6,6, and aromatic polyamides, etc., are used as resin materials. Other examples of the above-mentioned resin materials include imide-based polymers, silo-based polymers, polyether s-series polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, and vinyl alcohol-based polymers. Polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and the like. It may also be a substrate comprising a blend of two or more of the above-mentioned polymers.

Various additives such as antioxidants, ultraviolet absorbers, plasticizers, colorants (pigments, dyes, etc.) can also be blended into the resin material constituting the above-mentioned base material as required. For example, known or commonly used surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and primer coating can be performed. Such surface treatment may be, for example, treatment for improving the adhesion between the base material and the adhesive layer (the tackiness of the adhesive layer).

As the above-mentioned base material, those subjected to antistatic treatment can also be used. By using the above-mentioned base material, the electrification of the surface protective film itself at the time of peeling can be suppressed, which is preferable. In addition, by applying antistatic treatment to the above-mentioned base material, the electrification of the surface protection film itself can be reduced, and a base material having excellent antistatic ability to the adherend can be obtained. Furthermore, there is no particular limitation on the method for imparting an antistatic function, and conventionally known methods can be used, for example, coating an antistatic resin containing an antistatic agent and a resin component, a conductive polymer, a Methods of conductive resins for substances; methods of vapor deposition or plating of conductive substances, and methods of kneading antistatic agents, etc.

As thickness of the said base material, 6-100 micrometers are preferable, 10-60 micrometers are more preferable, and 15-40 micrometers are still more preferable. If the thickness of the said base material is in the said range, since the workability|operativity of sticking to an adherend and the peelability or workability|operativity from a to-be-adhered body are excellent, it is preferable.

The surface protection film disclosed here can also be implemented in the aspect which contains other layers besides a base material and an adhesive bond layer. As said other layer, the primer layer (tackifier layer) etc. which improve the grip property of an antistatic layer or an adhesive layer are mentioned. In addition, in order to protect the surface of the adhesive layer, a separator may be attached.

<Adhesive layer> The optical surface protective film of the present invention is characterized by providing an adhesive layer formed of an adhesive composition on one side of the above-mentioned base material. The adhesive layer used in the present invention can be used without any particular limitation as long as it is formed of an adhesive composition containing an adhesive polymer having adhesive properties. As the above-mentioned adhesive composition, for example, acrylic adhesives, urethane-based adhesives, synthetic rubber-based adhesives, natural rubber-based adhesives, polysiloxane-based adhesives, polyester-based adhesives, and the like can be used, Among these, it is preferable to use the adhesive composition containing a (meth)acrylic-type polymer and/or a urethane-type polymer as a base polymer.

<Acrylic adhesive> In the case where an acrylic adhesive is used for the above-mentioned adhesive layer, the (meth)acrylic polymer that is an adhesive polymer constituting the above-mentioned acrylic adhesive is used as a base polymer, and the As the raw material monomer, a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used as the main monomer. As said (meth)acrylic-type monomer, 1 type or 2 or more types can be used. By using the above-mentioned (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) to the adherend (to be protected) low, and light weight can be obtained. Surface protection film with excellent peelability or repeelability. Furthermore, the (meth)acrylic polymer in the present invention refers to an acrylic polymer and/or a methacrylic polymer, and the (meth)acrylate refers to an acrylate and/or a methacrylate .

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, and n-(meth)acrylate. Butyl, 2-butyl (meth)acrylate, 3-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate Ester, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylate ) isodecyl acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, etc.

Among them, in the surface protective film of the present invention, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-(meth)acrylate Octyl ester, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, (meth)acrylate (meth)acrylic acid system having an alkyl group with a carbon number of 4 to 14, such as n-dodecyl acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, etc. Monomers are suitable monomers. In particular, by using the (meth)acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) to the adherend to be low, and it becomes one that is excellent in releasability.

In particular, the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms is preferably contained in an amount of 65% by weight or more relative to 100% by weight of the total amount of monomer components constituting the (meth)acrylic polymer. It is more preferably 75% by weight or more, still more preferably 85 to 99.9% by weight, and still more preferably 90 to 99% by weight. If it is less than 65 weight%, since the moderate wettability of an adhesive composition or the cohesion of an adhesive layer will worsen, it is unfavorable.

Moreover, the said (meth)acrylic-type polymer can use the (meth)acrylic-type monomer containing a hydroxyl group as a raw material monomer. As for the above-mentioned hydroxyl-containing (meth)acrylic monomer, one type or two or more types may be used. By using the above-mentioned hydroxyl-containing (meth)acrylic monomer, it is easy to control the crosslinking of the adhesive composition, etc., and further to easily control the improvement of wettability by flow and the peeling force (adhesive force) during peeling The balance of the reduction.

As said hydroxyl group-containing (meth)acrylic monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate can be mentioned. , 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxyl acrylate) methylcyclohexyl) methyl ester, N-methylol (meth) acrylamide, etc.

The above-mentioned hydroxyl-containing (meth)acrylic monomer is preferably contained in an amount of 25% by weight or less, more preferably 15% by weight, relative to 100% by weight of the total amount of monomer components constituting the (meth)acrylic polymer. Hereinafter, it is more preferably 0.1 to 10% by weight, particularly preferably 1 to 5% by weight. Within the above range, it is easy to control the balance between the wettability of the adhesive composition and the cohesive force of the obtained adhesive layer, which is preferable.

In addition, as another polymerizable monomer component, it can be used for adjusting the glass transition temperature or peeling of the (meth)acrylic polymer within a range that does not impair the effect of the present invention, because it is easy to obtain the balance of the adhesive properties. The polymerizable monomer and the like are used so that the Tg is 0°C or lower (usually -100°C or higher).

Moreover, the said (meth)acrylic-type polymer can use the (meth)acrylic-type monomer containing a carboxyl group as a raw material monomer. By using the above-mentioned carboxyl group-containing (meth)acrylic monomer, the increase in the time-dependent adhesive force of the adhesive layer (surface protective film) can be suppressed, and the re-peelability, the increase in the anti-adhesion force, and the workability are excellent. Moreover, since the cohesion force of the adhesive layer and the shear force are also excellent, it is preferable.

As said carboxyl group-containing (meth)acrylic-type monomer, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, etc. are mentioned, for example.

The amount of the carboxyl group-containing (meth)acrylic monomer is preferably 10% by weight or less, more preferably 0 to 8, relative to 100% by weight of the total amount of the monomer components constituting the (meth)acrylic polymer. % by weight, more preferably 0 to 6% by weight. If it exists in the said range, since it becomes easy to control the balance between the wettability of an adhesive composition and the cohesion of the adhesive layer obtained, it is preferable.

Furthermore, as long as the said (meth)acrylic-type polymer is the range which does not impair the characteristic of this invention, other polymerizable monomers other than the said raw material monomer can be used without particular restriction. For example, as the above-mentioned other polymerizable monomers, components that improve cohesion and heat resistance, such as cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers, etc.; Imide group monomers, amine group-containing monomers, epoxy group-containing monomers, N-acrylomorpholine, vinyl ether monomers, etc. improve the peeling force (adhesion) or function as a crosslinking base point. Composition of functional groups. Among them, nitrogen-containing monomers such as cyano group-containing monomers, amide group-containing monomers, amide imine group-containing monomers, amine group-containing monomers, and N-acrylomorpholine are preferably used. By using a nitrogen-containing monomer, a suitable peeling force (adhesive force) such as no swelling or peeling can be ensured, and a surface protective film excellent in shear force can be obtained, which is useful. One or two or more of these polymerizable monomers can be used.

As said cyano group containing monomer, acrylonitrile and methacrylonitrile are mentioned, for example.

Examples of the above-mentioned amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylacrylamide, N-vinylpyrrolidone ,N-Dimethylmethacrylamide, N,N-Diethylacrylamide, N,N-Diethylmethacrylamide, N,N'-methylenebisacrylamide, N , N-dimethylaminopropyl acrylamide, N,N-dimethylaminopropyl methyl acrylamide, diacetone acrylamide, etc.

Examples of the above-mentioned imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, iconimide, and the like.

As the above-mentioned amino group-containing monomer, for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethyl (meth)acrylate can be mentioned. aminopropyl ester, etc.

As said vinyl ester monomer, vinyl acetate, vinyl propionate, vinyl laurate, etc. are mentioned, for example.

As said aromatic vinyl monomer, styrene, chlorostyrene, chloromethylstyrene, alpha-methylstyrene, other substituted styrene etc. are mentioned, for example.

As said epoxy group-containing monomer, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether, etc. are mentioned, for example.

As said vinyl ether monomer, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. are mentioned, for example.

In the present invention, the other polymerizable monomer is preferably 0 to 30 wt %, more preferably 0 to 10 wt %, relative to 100 wt % of the total amount of monomer components constituting the (meth)acrylic polymer. The other polymerizable monomers described above can be appropriately adjusted in order to obtain desired properties.

The said (meth)acrylic-type polymer may further contain the reactive monomer containing an oxyalkylene group as a monomer component.

Further, from the viewpoint of compatibility with the oxyalkylene compound, the average number of added moles of the oxyalkylene unit of the above-mentioned oxyalkylene-containing reactive monomer is preferably 1 to 40, More preferably, it is 3-40, More preferably, it is 4-35, Especially preferably, it is 5-30. When the said average added mole number is 1 or more, there exists a tendency for the contamination reduction effect of an adherend (to-be-protected body) to be obtained efficiently. Moreover, when the above-mentioned average added molar number exceeds 40, the interaction with the oxygen-containing alkylene compound is large, and the viscosity of the adhesive composition tends to increase, making application difficult, which is not preferable. Furthermore, the end of the oxyalkylene chain may be directly hydroxy, or may be substituted with other functional groups.

The above-mentioned reactive monomers containing oxyalkylene groups can be used alone or in combination of two or more kinds, and the overall content thereof is preferably 0-20% in the total amount of the monomer components of the above-mentioned (meth)acrylic polymer. % by weight, more preferably 0 to 10% by weight. When the content of the reactive monomer containing an oxyalkylene group exceeds 20% by weight, the contamination to the adherend becomes poor, which is not preferable.

As the oxyalkylene unit of the above-mentioned oxyalkylene-containing reactive monomer, those having an alkylene group having 1 to 6 carbon atoms can be mentioned, and examples thereof include oxymethylene, oxyethylene, and oxypropylene. base, oxybutylene, etc. The hydrocarbon group of the oxyalkylene chain may be straight or branched.

Moreover, it is more preferable that the reactive monomer containing an oxyalkylene group is a reactive monomer having an oxyethylene group. By using a (meth)acrylic polymer containing a reactive monomer having an oxyethylene group as the base polymer, the compatibility between the base polymer and the oxyalkylene compound is improved, and the tendency to stick to the oxyalkylene compound is appropriately suppressed. The exudation of the body can obtain a low-polluting adhesive composition.

Examples of the reactive monomer containing an oxyalkylene group include (meth)acrylic acid alkylene oxide adducts, reactive substituents such as acryl group, methacryloyl group, and allyl group in the molecule. Reactive surfactants, etc.

Specific examples of the above-mentioned (meth)acrylic acid alkylene oxide adduct include, for example, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol-polypropylene glycol (methyl) base) acrylate, polyethylene glycol-polybutylene glycol (meth)acrylate, polypropylene glycol-polybutylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethylene glycol Oxy polyethylene glycol (meth)acrylate, butoxy polyethylene glycol (meth)acrylate, octoxy polyethylene glycol (meth)acrylate, lauryloxy polyethylene glycol (methyl) base) acrylate, stearyloxy polyethylene glycol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, octoxypolyethylene glycol (meth)acrylate Ethylene glycol-polypropylene glycol (meth)acrylate, etc.

Moreover, as a specific example of the said reactive surfactant, the anionic reactive surfactant which has a (meth)acryloyl group or an allyl group, a nonionic reactive surfactant, a cationic reactive surfactant, for example is mentioned. surfactants, etc.

The weight average molecular weight (Mw) of the above-mentioned (meth)acrylic polymer is preferably 100,000 to 5 million, more preferably 200,000 to 4 million, further preferably 300,000 to 3 million, and most preferably 300,000 to 300,000. 1.2 million. When the weight-average molecular weight is less than 100,000, the cohesion force of the obtained adhesive layer tends to be small and paste residue tends to occur. On the other hand, when the weight average molecular weight exceeds 5 million, the fluidity of the polymer decreases, and the wetting of the adherend (such as a polarizing plate) is insufficient, and it becomes an adhesive between the adherend and the surface protective film. The tendency to cause bulges between layers. In addition, the weight average molecular weight means the molecular weight obtained by measuring by GPC (gel permeation chromatography).

Moreover, the glass transition temperature (Tg) of the said (meth)acrylic-type polymer becomes like this. Preferably it is 0 degreeC or less, More preferably, it is -10 degreeC or less (normally -100 degreeC or more). When the glass transition temperature is higher than 0°C, it is difficult for the polymer to flow, for example, the wetting of the polarizing plate as an optical member is insufficient, which is the cause of the bulge generated between the polarizing plate and the adhesive layer of the surface protection film. tendency of the cause. In particular, by setting the glass transition temperature to -70°C or lower, it is easy to obtain an adhesive layer excellent in wettability to a polarizing plate and light releasability. In addition, the glass transition temperature of a (meth)acrylic-type polymer can be adjusted to the said range by suitably changing the monomer component or composition ratio used.

The polymerization method of the above-mentioned (meth)acrylic polymer is not particularly limited, and the polymerization can be carried out by known methods such as solution polymerization, emulsion polymerization, block polymerization, and suspension polymerization. In terms of properties such as low contamination of the protected body), solution polymerization is a better aspect. Moreover, the polymer obtained may be a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, or the like.

<Urethane-based adhesive> When using a urethane-based adhesive in the above-mentioned adhesive layer, any appropriate urethane-based adhesive can be used. As such a urethane-based adhesive, an adhesive polymer obtained by reacting a polyol and a polyisocyanate compound, that is, a urethane-based polymer, is preferably used as a base polymer. As the urethane-based adhesive, one containing a polyurethane-based resin, which is obtained by curing a composition containing a polyol and a polyisocyanate compound, can be used.

The lower limit of the content ratio of the polyurethane-based resin in the urethane-based adhesive is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 55% by weight or more % by weight or more, more preferably 60% by weight or more, particularly preferably 65% by weight or more, and most preferably 70% by weight or more, and the upper limit is preferably 99.999% by weight or less, more preferably 99.99% by weight or less, More preferably, it is 99.9 wt % or less, still more preferably 99 wt % or less, particularly preferably 95 wt % or less, and most preferably 90 wt % or less. Only one type of the above-mentioned polyurethane-based resin may be used, or two or more types may be used.

Moreover, the said polyhydric alcohol may be only 1 type, and may be 2 or more types.

As the above-mentioned polyol, any appropriate polyol can be used as long as it is a polyol having two or more OH groups. Examples of such polyols include polyols (diols) having two OH groups, polyols (triols) having three OH groups, and polyols (tetraols) having four OH groups. ), polyols with 5 OH groups (pentahydric alcohols), polyols with 6 OH groups (hexahydric alcohols), and the like.

In addition, as the above-mentioned polyol, a polyol (triol) having three OH groups can be preferably used. In this way, by using a polyol (triol) having 3 OH groups as the polyol, for example, an adhesive layer with a faster wetting speed can be made, and by combining with the specific substrate used in the present invention, It can provide a surface protection film with a higher detection rate of damage or impurity mixing. The content ratio of the polyol (triol) having 3 OH groups in the polyol is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, more preferably 80 to 100% by weight, and more preferably It is preferably 90 to 100% by weight, more preferably 95 to 100% by weight, and most preferably substantially 100% by weight.

As said polyol, the polyol which can contain the number average molecular weight (Mn) of 400-20000 is preferable. The content ratio of the polyol having a number average molecular weight (Mn) of 400 to 20,000 in the polyol is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, further preferably 90 to 100% by weight, particularly preferably It is 95 to 100% by weight, and the most preferably is substantially 100% by weight.

In the present invention, the polyol (triol) having three OH groups as the polyol is preferably a triol having a number-average molecular weight (Mn) of 7,000 to 20,000, and a number-average molecular weight (Mn) of 2,000. Trivalent alcohol of ~6000 and number average molecular weight (Mn) of 400 to 1900 are used in combination, and it is more preferable to use trivalent alcohol of number average molecular weight (Mn) of 8000 to 15000 and number average molecular weight (Mn) of 2000 A triol with a number-average molecular weight (Mn) of 500-1800 and a triol with a number-average molecular weight (Mn) of 500-1800 are used in combination. A trihydric alcohol of 2000-4000 and a trihydric alcohol having a number average molecular weight (Mn) of 500-1500 are used in combination.

As said polyol, polyester polyol, polyether polyol, polycaprolactone polyol, polycarbonate polyol, castor oil type polyol, etc. are mentioned, for example.

As said polyester polyol, it can obtain, for example by the esterification reaction of a polyol component and an acid component.

As said polyol component, ethylene glycol, diethylene glycol, 1, 3- butanediol, 1, 4- butanediol, neopentyl glycol, 3-methyl-1, 5-pentane are mentioned, for example Diol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol , 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylol Propane, pentaerythritol, hexanetriol, polypropylene glycol, etc.

Examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, and 1,14-tetradecane Diacid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, o- Phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, anhydrides of these, etc.

Examples of the above-mentioned polyether polyol include water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerol, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), dihydroxybenzene (Catechol, resorcinol, hydroquinone, etc.) as initiators, polyethers obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc. Polyol. Specifically, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. are mentioned, for example.

As said polycaprolactone polyol, the caprolactone type polyester diol etc. obtained by ring-opening polymerization of cyclic ester monomers, such as ε-caprolactone and σ-valerolactone, are mentioned, for example.

Examples of the above-mentioned polycarbonate polyol include: a polycarbonate polyol obtained by subjecting the above-mentioned polyol component to a polycondensation reaction with phosgene; Propyl, diisopropyl carbonate, dibutyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, dibenzyl carbonate and other carbonic diesters are obtained by transesterification condensation Polycarbonate polyols; Copolycarbonate polyols obtained by combining two or more of the above-mentioned polyol components; Polycarbonate polyols obtained by esterification of the above-mentioned various polycarbonate polyols with carboxyl-containing compounds ; Polycarbonate polyols obtained by etherifying the above-mentioned various polycarbonate polyols with hydroxyl-containing compounds; Polycarbonate polyols obtained by transesterifying the above-mentioned various polycarbonate polyols with ester compounds; Polycarbonate polyols obtained by transesterification of the above-mentioned various polycarbonate polyols with hydroxyl-containing compounds; polyester-based polycarbonates obtained by polycondensation reaction of the above-mentioned various polycarbonate polyols with dicarboxylic acid compounds Polyols; copolyether-based polycarbonate polyols obtained by copolymerizing the above-mentioned various polycarbonate polyols and alkylene oxides, and the like.

As said castor oil type polyol, the castor oil type polyol obtained by making a castor oil fatty acid react with the said polyol component is mentioned, for example. Specifically, for example, castor oil-based polyols obtained by reacting castor oil fatty acid and polypropylene glycol can be mentioned.

Only one type of the above-mentioned polyisocyanate compound (polyfunctional isocyanate compound) may be used, or two or more types may be used.

As the above-mentioned polyisocyanate compound (polyfunctional isocyanate compound), any appropriate polyisocyanate compound that can be used in the urethane reaction can be used. As such a polyisocyanate compound, a polyfunctional aliphatic isocyanate compound, a polyfunctional alicyclic isocyanate, a polyfunctional aromatic isocyanate compound etc. are mentioned, for example.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, and 1,2-propylene diisocyanate. , 1,3-butylene diisocyanate, dodecylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, and isophorone diisocyanate. Isocyanates, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, and the like.

As said polyfunctional aromatic diisocyanate compound, benzene diisocyanate, 2, 4- toluene diisocyanate, 2, 6- toluene diisocyanate, 2, 2'- diphenylmethane diisocyanate, 4 ,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate , xylylene diisocyanate, etc.

Examples of the polyisocyanate compound include trimethylolpropane adducts of various polyfunctional isocyanate compounds as described above, biurets obtained by reacting with water, and trimers having an isocyanurate ring. Wait. Moreover, you may use these together.

The content ratio of the polyisocyanate compound is preferably 5 to 60 parts by weight, more preferably 10 to 50 parts by weight, and still more preferably 15 to 40 parts by weight relative to 100 parts by weight of the above-mentioned polyol.

The equivalent ratio of NCO groups and OH groups in the polyol and the polyisocyanate compound is preferably more than 1.0 and 5.0 or less in terms of NCO groups/OH groups, more preferably 1.1 to 5.0, still more preferably 1.2 to 4.0, particularly preferably It is 1.5 to 3.5, and the best is 1.8 to 3.0.

The above-mentioned polyurethane-based resin may contain a fatty acid ester which can be used as a wettability additive. Wetting rate can be improved by making a urethane-type resin contain a fatty acid ester. Only one type of fatty acid ester may be used, or two or more types may be used.

The content ratio of the fatty acid ester is preferably 5 to 50 parts by weight, more preferably 10 to 45 parts by weight, more preferably 1 to 40 parts by weight, and particularly preferably 20 to 35 parts by weight relative to 100 parts by weight of the above-mentioned polyol The optimum weight part is 25 to 30 parts by weight. By adjusting the content ratio of the fatty acid ester within the above range, the wetting rate can be further improved. When the content rate of the fatty acid ester is too small, there is a possibility that the wetting rate cannot be sufficiently improved. If the content ratio of the fatty acid ester is too large, there is a problem of being disadvantageous in cost, a problem of not being able to maintain the adhesive properties, or a problem of contamination of the adherend.

The number average molecular weight (Mn) of the fatty acid ester is preferably 200-400, more preferably 210-395, further preferably 230-380, particularly preferably 240-360, and most preferably 270-340. By adjusting the number average molecular weight (Mn) of the fatty acid ester within the above range, the wetting speed can be further improved. If the number-average molecular weight (Mn) of the fatty acid ester is too small, there is a possibility that the wetting speed will not increase even if the amount of the compound is large. If the number-average molecular weight (Mn) of the fatty acid ester is too large, the sclerosing properties of the adhesive at the time of drying may deteriorate, and there is a possibility that not only the wetting properties but also other adhesive properties may be adversely affected.

As the above-mentioned fatty acid ester, any appropriate fatty acid ester can be used within a range that does not impair the effects of the present invention. Examples of such fatty acid esters include polyoxyethylene bisphenol A laurate, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, and monobehenate. Glycerides, Cetyl 2-Ethylhexanoate, Isopropyl Myristate, Isopropyl Palmitate, Cholesteryl Isostearate, Lauryl Methacrylate, Methyl Coconut Fatty Acid, Methyl Laurate, Methyl Oleate, Methyl Stearate, Myristyl Myristate, Octyldodecyl Myristate, Pentaerythritol Monooleate, Pentaerythritol Monostearate, Pentaerythritol Tetrapalmitate, Stearic Acid Stearate, isotridecyl stearate, triglyceride 2-ethylhexanoate, butyl laurate, octyl oleate, etc.

The above-mentioned polyurethane-based resin may contain a leveling agent. By including a leveling agent in the polyurethane-based resin, it is possible to prevent uneven appearance caused by orange peel. Only one type of the above-mentioned leveling agent may be used, or two or more types may be used.

As a method for obtaining a polyurethane-based resin by curing the above-mentioned composition containing a polyol and a polyisocyanate compound, a urethane-forming reaction method using block polymerization or solution polymerization can be used, which does not impair the present invention. any appropriate method within the scope of the effect. However, since there is a possibility that the effect of the present invention cannot be exhibited by the urethane-based resin obtained by the so-called urethane prepolymer, the above-mentioned composition containing a polyol and a polyisocyanate compound is cured. The method of obtaining the polyurethane-based resin is preferably a method other than the method of obtaining the polyurethane-based resin through a urethane prepolymer.

<Ultraviolet absorber> In the optical surface protective film of the present invention, the adhesive composition preferably contains an ultraviolet absorber, and the number of hydroxyl groups in the molecule of the ultraviolet absorber is preferably 3 or less. By using an ultraviolet absorber, a member that is easily degraded by ultraviolet rays can be protected, and by using an ultraviolet absorber having three or less hydroxyl groups, the adhesive layer has excellent adhesion stability, which is preferable. Furthermore, when there are many hydroxyl groups in the molecule|numerator of the said ultraviolet absorber, it is presumed that the ultraviolet absorber and the crosslinking agent react, and the curing of the adhesive composition is inhibited.

The above-mentioned ultraviolet absorber is not particularly limited, and examples thereof include trisulfan-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, hydroxybenzophenone-based ultraviolet absorbers, and salicylic acid. Ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and the like may be used alone or in combination of two or more. Among these, it is more preferable that the hydroxyl group in the molecule|numerator of the said ultraviolet absorber is 3 or less.

As a tertiary UV absorber having three or less hydroxyl groups in one molecule, specifically, 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl] -6-(4-Methoxyphenyl)-1,3,5-tris(Tinosorb S, manufactured by BASF); 2,4-bis[2-hydroxy-4-butoxyphenyl]-6- (2,4-Dibutoxyphenyl)-1,3,5-tris(TINUVIN 460, manufactured by BASF); 2-(4,6-bis(2,4-dimethylphenyl)-1 ,3,5-Tris(2-yl)-5-hydroxyphenyl and [(C ₁₀ -C ₁₆ (mainly C ₁₂ -C ₁₃ )alkoxy)methyl]oxirane reaction product (TINUVIN400, manufactured by BASF); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-tris-2-yl]-5-[3-(dodecane) oxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5- Reaction product of tris(2-ethylhexyl) glycidate (TINUVIN405, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-tris-2-yl)-5- [(hexyl)oxy]phenol (TINUVIN1577, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-tris-2-yl)-5-[2-(2-ethyl) Hexyloxy)ethoxy]phenol (ADK STAB LA46, manufactured by ADEKA); 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis( 4-phenylphenyl)-1,3,5-tris(TINUVIN479, manufactured by BASF) and the like.

As the above-mentioned benzotriazole-based ultraviolet absorber, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1, 1,3,3-Tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF) ), phenylpropionic acid and 3-(2H-benzotriazol- _{2-yl)-5-(1,1-dimethylethyl)-4-hydroxyl (C 7-9 side} chain and straight-chain alkyl ) ester compound (TINUVIN384-2, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN900, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl) yl)phenol (TINUVIN928, manufactured by BASF); methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol Reaction product of 300 (TINUVIN1130, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P, manufactured by BASF); 2-(2H-benzotriazol-2-yl) )-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN234, manufactured by BASF); 2-[5-chloro(2H)-benzotriazol-2-yl]-4- Methyl-6-tert-butylphenol (TINUVIN326, manufactured by BASF), (TINUVIN326 FL, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN328, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN329, manufactured by BASF); 3-( The reaction product of methyl 3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 (TINUVIN213, manufactured by BASF); 2 -(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN571, manufactured by BASF); 2-[2-hydroxy-3-(3,4,5,6 -Tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Industries, Ltd.) and the like.

As said benzophenone type ultraviolet absorber (benzophenone type compound), hydroxybenzophenone type ultraviolet absorber (hydroxybenzophenone type compound), 2, 4- dihydroxy diphenyl is mentioned, for example: Methanone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (acid anhydride and trihydrate salt), 2-hydroxy-4-octane oxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxy Benzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone (KEMISORB 111, manufactured by Chemipro Chemicals) )Wait.

As said salicylate type ultraviolet absorber (salicylate type compound), phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, 2-Propenyloxy-4-phenylmethylbenzoate, 2-propenyloxy-5-methylbenzoate phenyl, 2-propenyloxy-3-methoxyphenylbenzoate, 2 -phenyl hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, 2-hydroxy- Phenyl 3-methoxybenzoate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF), and the like.

Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include 2-cyanoacrylate alkyl ester, 2-cyanoacrylate cycloalkyl ester, and 2-cyanoacrylate alkoxy group. Alkyl ester, alkenyl 2-cyanoacrylate, alkynyl 2-cyanoacrylate, etc.

The above-mentioned ultraviolet absorbers can be used alone or in a mixture of two or more kinds, and relative to 100 parts by weight of the above-mentioned base polymer, the overall content of the above-mentioned ultraviolet absorbers is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight , and more preferably 1 to 10 parts by weight. By making the content of the ultraviolet absorber into the above-mentioned range, the ultraviolet absorption function of the adhesive layer can be fully exerted and the ultraviolet polymerization is not inhibited, which is preferable.

<Antioxidant> In the optical surface protective film of this invention, the said adhesive composition may contain an antioxidant, for example, a radical chain terminator, a peroxide decomposition agent, etc. are mentioned.

As said radical chain terminator, a phenolic antioxidant, an amine antioxidant, etc. are mentioned, for example.

As said peroxide decomposer, a sulfur type antioxidant, a phosphorus type antioxidant, etc. are mentioned, for example.

As said phenolic antioxidant, a monophenolic antioxidant, a bisphenolic antioxidant, a polymer type phenolic antioxidant, etc. are mentioned, for example.

As said monophenol type antioxidant, 2, 6- di-tert-butyl-p-cresol, butylated hydroxyanisole, 2, 6- di-tert-butyl-4-ethylphenol, β- (3,5-di-tert-butyl-4-hydroxyphenyl) stearyl propionate and the like.

As said bisphenol type antioxidant, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl), for example -6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylene bis(3-methyl-6- tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy] ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, etc.

As said polymer type phenolic antioxidant, for example, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris Methyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[methylene-3-(3',5'-di-tert-butyl- 4'-Hydroxyphenyl)propionate]methane, bis[3,3'-bis(4'-hydroxy-3'-tert-butylphenyl)butyric acid]diol, 1,3,5- Tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mestris-2,4,6-(1H, 3H, 5H)trione, tocopherol, pentaerythritol tetra[3-( 3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] and the like.

As said sulfur-based antioxidant, for example, dilauryl 3,3'-thiodipropionate, 3,3'-dimyristyl thiodipropionate, and 3,3'-thiodipropionic acid are mentioned. Distearate, etc.

As said phosphorus antioxidant, triphenyl phosphite, diphenyl phosphite isodecyl, phenyl phosphite diisodecyl, etc. are mentioned, for example.

The above-mentioned antioxidants can be used alone or in combination of two or more kinds, and relative to 100 parts by weight of the above-mentioned base polymer, the whole content of the above-mentioned antioxidants is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.8 part by weight, and further Preferably it is 0.2-0.7 weight part. By setting the content of the above-mentioned antioxidant in the above-mentioned range, the deterioration of the adhesive layer due to oxidation can be sufficiently suppressed, and the adhesive properties can be stabilized, which is preferable.

<The compound containing an oxygen alkylene group> The adhesive composition used by this invention may contain the compound containing an oxygen alkylene group. The light peeling property can be further expressed by the compound containing an oxyalkylene group. As the compound containing an oxyalkylene group, an organopolysiloxane having an oxyalkylene chain or a compound containing an oxyalkylene group which does not include an organopolysiloxane can be exemplified.

<Crosslinking agent> In the surface protection film of this invention, it is preferable that the said adhesive composition contains a crosslinking agent. Moreover, in this invention, the said adhesive composition can be used as an adhesive layer. For example, in the case where the above-mentioned adhesive composition is an acrylic adhesive containing the above-mentioned (meth)acrylic polymer, the structural unit, the structural ratio, the cross-linking ratio of the above-mentioned (meth)acrylic polymer can be adjusted appropriately. The selection of the linking agent and the addition ratio, etc., can be used for cross-linking to obtain an adhesive layer (surface protection film) with more excellent heat resistance. Moreover, in the case of the urethane-based adhesive containing the above-mentioned urethane-based polymer, it is carried out by appropriately adjusting the structural unit of the polyol, the structural ratio, the selection of the crosslinking agent, the ratio of the additives, and the like. By cross-linking, an adhesive layer (surface protective film) having excellent initial reworkability and excellent adhesion reliability over time can be obtained.

As the crosslinking agent used in the present invention, isocyanate compounds, epoxy compounds, melamine-based resins, aziridine derivatives, metal chelate compounds, etc. can be used, and isocyanate compounds or epoxy compounds are particularly preferred. In addition, these compounds may be used individually or in mixture of 2 or more types.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), and dimer acid diisocyanate; cyclopentylene diisocyanate, Cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane and other alicyclic isocyanates; 2,4-toluene diisocyanate, 4,4 '-diphenylmethane diisocyanate, xylylene diisocyanate (XDI) and other aromatic isocyanates; using allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea Bond, carbodiimide bond, uretonimide bond, diketone bond, etc. The polyisocyanate compound obtained by modifying the above-mentioned isocyanate compound. For example, commercial products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (the above are manufactured by Mitsui Chemicals Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (the above are manufactured by Sumika Bayer Urethane Co., Ltd.) , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (the above are manufactured by Tosoh Corporation), etc. These isocyanate compounds may be used alone, or two or more of them may be used in combination, or a bifunctional isocyanate compound and a trifunctional or more functional isocyanate compound may be used in combination. By using a cross-linking agent in combination, both adhesion and rebound resistance (adhesion to curved surfaces) can be achieved, and an adhesive layer (surface protective film) with better adhesion reliability can be obtained.

As said epoxy compound, for example, N,N,N',N'-tetraglycidyl-m-xylylenediamine (trade name TETRAD-X, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 1,3-bis(N , N-diglycidylaminomethyl)cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and the like.

As said melamine type-resin, hexamethylol melamine etc. are mentioned. As an aziridine derivative, the trade name HDU, TAZM, TAZO (the above are made by Mutual Pharmaceutical Co., Ltd.) etc. are mentioned, for example.

As the metal chelate compound, aluminum, iron, tin, titanium, nickel, etc. are mentioned as the metal component, and acetylene, methyl acetoacetate, ethyl lactate, etc. are mentioned as the chelate component.

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer, for example, More preferably, it is 0.5 to 10 parts by weight, and most preferably 1 to 8 parts by weight. In the case where the above-mentioned content is less than 0.01 parts by weight, the formation of cross-linking by the cross-linking agent becomes insufficient, the cohesive force of the obtained adhesive layer becomes small, and sufficient heat resistance cannot be obtained, and There is a tendency to cause paste residues. On the other hand, when the content exceeds 20 parts by weight, the cohesive force of the polymer is large, the fluidity is reduced, and the wetting of the adherend (such as a polarizing plate) is insufficient, and the adherend and the adhesive are formed. Tendency to cause bulge between layers (adhesive composition layers). In addition, these crosslinking agents may be used individually or in mixture of 2 or more types. Moreover, in the case of the urethane adhesive containing the urethane polymer, the content of the crosslinking agent is preferably 5 to 30 parts by weight relative to 100 parts by weight of the polyol. More preferably, it is 5-28 weight part, More preferably, it is 5-25 weight part, Especially preferably, it is 5-23 weight part. By adjusting the content of the above-mentioned crosslinking agent within the above-mentioned range, the obtained adhesive layer is excellent not only in initial adhesion but also in adhesion reliability after time when it is attached to an adherend.

<Cross-linking catalyst> The above-mentioned adhesive composition may further contain a cross-linking catalyst for making any of the above-mentioned cross-linking reactions proceed more efficiently. As the crosslinking catalyst, for example, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate (dioctyltin dilaurate); Alkane-2,4-dione)iron, tris(heptane-2,4-dione)iron, tris(heptane-3,5-dione)iron, tris(5-methylhexane-2, 4-diketo)iron, tris(octane-2,4-dione)iron, tris(6-methylheptane-2,4-dione)iron, tris(2,6-dimethylheptane) -3,5-dione)iron, tris(nonane-2,4-dione)iron, tris(nonane-4,6-dione)iron, tris(2,2,6,6-tetramethyl) Heptane-3,5-dione)iron, tris(tridecane-6,8-dione)iron, tris(1-phenylbutane-1,3-dione)iron, tris(hexafluoro) Acetate acetone) iron, tris (acetonitrile ethyl acetate) iron, tris (acetoacetate n-propyl acetate) iron, tris (acetate isopropyl acetate) iron, tris (acetonitrile n-butyl acetate) iron, tris (2-butylacetate)iron, tris(3-butylacetate)iron, tris(methylacetate)iron, tris(ethylacetate)iron, tris(n-propylacetate) Ester) iron, tris(propyl propyl acetate isopropyl) iron, tris(propyl propyl acetate n-butyl) iron, tris(propyl propyl acetate 2-butyl) iron, tris(propyl propyl acetate tertiary butyl) ) iron, tris(acetoxybenzyl acetate) iron, tris(dimethylmalonate) iron, tris(diethylmalonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy Iron-based catalysts such as base iron and ferric chloride. These crosslinking catalysts may be used alone or in combination of two or more.

Although content of the said crosslinking catalyst is not specifically limited, For example, it is preferable to set it as about 0.0001-1 weight part with respect to 100 weight part of said (meth)acrylic-type polymers, More preferably, it is 0.001-0.5 weight part. Within the above range, the rate of the cross-linking reaction during the formation of the adhesive layer becomes faster, and the pot life of the adhesive composition becomes longer, which is a preferable aspect. Moreover, only one type may be sufficient as it, and two or more types may be sufficient as it. Moreover, in the case of containing the urethane-based adhesive of the urethane-based polymer, the content of the crosslinking catalyst is preferably 0.01 to 0.01 parts by weight relative to 100 parts by weight of the polyol. 1 part by weight, more preferably 0.08 to 0.5 part by weight.

<Other additives> Further, other known additives may be contained in the above-mentioned adhesive composition within the range that does not impair the effect of the present invention. For example, powders such as lubricants, colorants, and pigments, and solvents may be appropriately added according to the application. , plasticizer, softener, tackifier, low molecular weight polymer, surface lubricant, leveling agent, wetting additive, antioxidant, anti-corrosion agent, light stabilizer, heat-resistant stabilizer, ultraviolet absorber, polymerization inhibitor agents, silane coupling agents, antistatic agents, inorganic or organic fillers, metal powders, granules, foils, etc.

<Surface protective film for optics> The surface protective film (surface protective film) for optics of the present invention is provided with a substrate containing a polyester resin, and an adhesive layer formed of an adhesive composition on one side of the substrate. At this time, the cross-linking of the adhesive composition is usually performed after the coating of the adhesive composition, but the adhesive layer including the cross-linked adhesive composition may also be transferred to a substrate or the like.

In addition, the method of forming the adhesive layer on the substrate is not particularly limited. For example, it can be prepared by applying the above-mentioned adhesive composition (solution) to the substrate, drying and removing the polymerization solvent, etc. An adhesive layer is formed on the material. After that, curing is performed in order to adjust the component transfer of the adhesive layer, to adjust the cross-linking reaction, and the like. Furthermore, when the surface protective film is produced by coating the adhesive composition on the base material, one or more solvents other than the polymerization solvent may be newly added to the above-mentioned adhesive composition so that it can be uniformly coated on the base material. .

Moreover, as the formation method of the adhesive bond layer at the time of manufacture of the surface protection film of this invention, the well-known method used for manufacture of an adhesive tape etc. is used. Specifically, for example, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an extrusion coating method using a die coater, etc. can be mentioned. .

The thickness of the above-mentioned adhesive layer is preferably 1-30 μm, more preferably 2-28 μm, and still more preferably 3-25 μm. If the thickness of the adhesive layer is within the above-mentioned range, it is easy to obtain a balance between moderate re-peelability and adhesiveness, which is preferable.

The surface protective film of the present invention preferably has a total thickness of 7 to 130 μm, more preferably 10 to 100 μm, and still more preferably 20 to 50 μm. Within the above-mentioned range, adhesive properties (removability, tackiness, adhesive force stability, etc.), workability, and appearance properties are excellent, which is a preferable aspect. Furthermore, the above-mentioned total thickness refers to the total thickness of all layers including the base material, the adhesive layer, the release film and other layers.

<Separation film> The surface protection film of the present invention may also be attached to a separation film as required to protect the surface of the adhesive layer.

As a material constituting the above-mentioned separator, there are paper or plastic film, and it is preferable to use a plastic film from the viewpoint of excellent surface smoothness. The film is not particularly limited as long as it can protect the above-mentioned adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, Polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the above-mentioned separator is usually about 5 to 200 μm, preferably about 8 to 100 μm, and more preferably about 10 to 50 μm. The above-mentioned isolation film can also be subjected to mold release and antifouling treatment using polysiloxane-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agents, silicon dioxide powder, etc., or coating type according to needs. , Kneading type, evaporation type and other antistatic treatment.

The surface protective film disclosed here may be implemented in a form including other layers in addition to the support and the adhesive layer. As said other layer, the primer layer (tackifier layer) etc. which improve the grip property of an antistatic layer or an adhesive layer are mentioned.

<The method of using the optical surface protective film> As the method of using the optical surface protective film of the present invention, for example, the surface of the adhesive layer constituting the optical surface protective film of the present invention is bonded to a part of the printing portion of the printing glass. In the step of UV hardening on the surface of the optical fiber, the exposed part of the optical surface protective film is coated with UV curable resin to prevent the uncoated part of the optical surface protective film attached with UV curable resin from being damaged by ultraviolet rays. lead to deterioration. According to this method of use, a curing reaction can be performed by irradiation with ultraviolet rays, and members such as a printed portion to be prevented from being deteriorated by irradiation with ultraviolet rays are protected, which is useful.

<Optical member> In this invention, an optical member can be protected by sticking the surface of the adhesive layer of the said surface protection film for optics to an optical member. The above-mentioned surface protection film can prevent the increase of the adhesive force even when it is heated after being attached to an optical member, etc., which is a to-be-adhered body as an adhesive layer, and has excellent adhesive force stability and excellent re-peelability, so it can be used. Since it is used for surface protection purposes (surface protection films) at the time of processing, conveying, and shipping, etc., it is useful for protecting the surfaces of the above-mentioned optical members (polarizing plates, etc.). In addition, the change in the hue of the adhesive layer constituting the surface protection film is suppressed, and the ultraviolet transmittance of the entire surface protection film is suppressed to be low, so that the inspection can be performed in the state where the surface protection film is attached to the optical member, or It is a preferable aspect because it is used for the purpose of suppressing hardening or deterioration accompanying ultraviolet irradiation. [Example]

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to these specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified. In addition, the compounding amount (addition amount) in the table is shown.

In addition, each characteristic in the following description was measured or evaluated as follows, respectively.

<Measurement of glass transition temperature (Tg) of acrylic polymer> The glass transition temperature (Tg) (°C) was determined by using the following literature value as the glass transition temperature Tgn (°C) of the homopolymer formed from each monomer, and according to It is calculated|required by the following formula. Formula: 1/(Tg+273)=Σ[Wn/(Tgn+273)] (In the formula, Tg(°C) represents the glass transition temperature of the copolymer, Wn(-) represents the weight fraction of each monomer, and Tgn(°C) represents Glass transition temperature of homopolymer formed from each monomer, n represents the kind of each monomer) Literature value: 2-ethylhexyl acrylate (2EHA): -70°C 2-hydroxyethyl acrylate (HEA): -15°C In addition, as the literature value, "Synthesis, Design and New Application Development of Acrylic Resin" (published by the Central Business Development Center Publishing Department) was referred to.

<Measurement of the weight average molecular weight (Mw) of the acrylic polymer> The weight average molecular weight (Mw) of the (meth)acrylic polymer used was measured using a GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation Determination. The measurement conditions are as follows. Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution) Sample injection volume: 10 μl Eluent: THF flow rate: 0.6 ml/min Measurement temperature: 40°C Column: Sample column: TSKguardcolumn SuperHZ-H (1 piece) + TSKgel SuperHZM-H (two pieces) Reference column: TSKgel SuperH-RC (one piece) Detector: Differential refractometer (RI) In addition, the weight average molecular weight was calculated|required by polystyrene conversion value. In addition, when measuring the number average molecular weight (Mn), it is not limited to the acrylic polymer, and it measures similarly to the weight average molecular weight (Mw).

<Determination of b* value> The optical surface protection film (surface protection film) of each example was aged at room temperature for 7 days, and then cut into a size of 50 mm in width and 50 mm in length, and the separator was removed from the surface protection film. After the surface of the adhesive layer was peeled off, the "b* value" was measured using a high-speed integrating sphere transmittance tester (manufactured by Murakami Color Institute, model "DOT-3C"). Again, b* values refer to CIELab values.

The b* value of the said surface protective film is 2 or less, Preferably it is 1.6 or less, More preferably, it is 1.2 or less. If the b* value is within the above range, the change in the hue of the adhesive layer can be suppressed, and the inspection can be performed even in the state of being attached to the optical member, which is a level that has no practical problems, and is therefore preferable.

<Measurement of transmittance> The transmittance was measured using a spectrophotometer U-4100 manufactured by Hitachi, Inc., and light with a wavelength of 300 to 400 nm was vertically incident on the substrate side of the optical surface protection films obtained in Examples and Comparative Examples. The transmittance (%) was obtained on the surface of the substrate. In addition, transmittance (ultraviolet transmittance) represents transmittance (%) at a wavelength of 365 nm among transmittances of light having a wavelength within the above range.

The said transmittance is 2% or less, preferably 1.8% or less, more preferably 1.6% or less. If the above transmittance exceeds 2%, the transmittance of ultraviolet rays is high, and hardening or deterioration due to ultraviolet irradiation cannot be prevented, for example, problems such as reduction in strength of the printed part occur, which is not preferable.

<Initial adhesive force (adhesion before heating)> The surface protective film of each example was cut into a width of 25 mm, and the adhesive layer side of the optical surface protective film after peeling the separator was attached to the glass using a 2 kg roller. The surface of the plate (manufactured by Matsunami Glass Industrial Co., Ltd., trade name: Micro Slide Glass S) was then left at room temperature (23°C, 50% RH) for 20 minutes, and then tested by a tensile compression tester (device name "TG" -1kN", manufactured by Minebea Co., Ltd.) peeled off under the conditions of a peeling angle of 180° and a peeling speed of 0.3 m/min, and the peeling force (relative glass adhesion) of the surface protective film was measured as "initial adhesion (adhesion before heating )” (N/25 mm). Measurement conditions: temperature: 23±2℃, humidity: 50±5%RH

<Adhesion after heating> A test piece was prepared in the same manner as the above-mentioned initial adhesion, heated at 100° C. for 30 minutes, and then left at room temperature (23° C., 50% RH) for 1 hour. "Adhesion after heating" (N/25 mm) was measured under the same conditions as initial adhesion.

The relative glass adhesion is preferably 0.2 N/25 mm or less both at the initial stage (before heating) and after heating, more preferably 0.15 N/25 mm or less, and still more preferably 0.1 N/25 mm or less. If the above-mentioned adhesive force exceeds 0.2 N/25 mm, the adhesive force becomes too high, and it becomes difficult to achieve light peelability (repeelability). There is a risk of paste residue on the adherend or damage to the base material, which is not preferable.

<Change rate of adhesive force before and after heating> The change rate of adhesive force before and after heating was calculated by the following formula. (Rate of change in adhesive force before and after heating (%)) = 100 × (adhesive force after heating - adhesive force before heating)/(adhesive force before heating)

The change rate of the adhesive force before and after the heating is ±30% or less, preferably ±25% or less, more preferably ±20% or less. If the above-mentioned rate of change exceeds ±30%, it is unfavorable because it causes heavy peeling or peeling problems.

[Example 1] [Preparation of acrylic polymer] 200 parts by weight of 2-ethylhexyl acrylate (2EHA) and 2-hydroxy acrylate were put into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser. 8 parts by weight of ethyl ester (HEA), 0.4 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 312 parts by weight of ethyl acetate as a solvent, while stirring slowly, nitrogen was introduced into the flask. The liquid temperature was maintained at around 65°C, and a polymerization reaction was performed for 6 hours to prepare an acrylic polymer solution (40% by weight). The weight average molecular weight (Mw) of the said acrylic polymer was 540,000, and the glass transition temperature (Tg) was -68 degreeC.

[Preparation of Acrylic Adhesive Solution] The above-mentioned acrylic polymer solution (40% by weight) was diluted with ethyl acetate to 29% by weight, and added as a crosslinking agent with respect to 100 parts by weight of solid content in the solution. 4 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry, trade name: Coronate HX, "C/HX" in Table 1), dilaurate dilaurate as a crosslinking catalyst Butyltin (manufactured by Tokyo Fine Chemical Co., Ltd., trade name: EMBILIZER OL-1, "OL-1" in Table 1, 0.5% by weight ethyl acetate solution) 0.015 parts by weight, 2,4-bis[{ 4-(4-Ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-tris(trade name: Tinosorb S, manufactured by BASF) 2 parts by weight and 3 parts by weight of acetone acetone as a crosslinking retarder with respect to the total solvent amount were mixed and stirred to obtain an acrylic adhesive solution (adhesive composition).

[Production of optical surface protective film] The above-mentioned acrylic adhesive solution was coated on a polyethylene terephthalate film (trade name: Diafoil T100G38, manufactured by Mitsubishi Plastics Co., Ltd.) with an antistatic treatment layer as a base material. The surface opposite to the antistatic treated surface with a thickness of 38 μm) was heated at 130° C. for 1 minute to form an adhesive layer with a thickness of 21 μm. Then, the polysiloxane-treated surface of the isolation film (polysiloxane-treated polyethylene terephthalate film with a thickness of 21 μm on one side) was attached to the surface of the above-mentioned adhesive layer, thereby producing an optical fiber. Surface protection film.

<Examples 2-5, Comparative Examples 1-3> Based on the preparation content shown in Table 1, the surface protective film for optics was produced by the method similar to Example 1.

<Examples 6 and 7> A polyester film with a thickness of 12 μm (manufactured by Mitsubishi Plastics Co., Ltd., trade name: Diafoil T100G12) was used instead of the base material used in Example 1. Example 1 A surface protective film for optics was produced by the same method.

<Examples 8 and 9> A polyester film with a thickness of 80 μm (manufactured by Toyobo Co., Ltd., trade name: SRF) was used instead of the base material used in Example 1. The same method was used to produce the optical surface protection film.

<Example 10> [Preparation of urethane-based adhesive solution] 85 parts by weight of PREMINOL S3011 (manufactured by Asahi Glass Co., Ltd., Mn=10000), SANNIX GP3000 (manufactured by Sanyo Chemical Industries, Ltd., Mn=10000) were used as polyols. 3000) 13 parts by weight, SANNIX GP1000 (manufactured by Sanyo Chemical Industry Co., Ltd., Mn=1000) 2 parts by weight, 10 parts by weight of Tinuvin 384-2 (manufactured by BASF) as a UV absorber, polyfunctional alicyclic as a cross-linking agent 18 parts by weight of an isocyanate compound (manufactured by Tosoh, trade name: Coronate HX), 0.08 part by weight of a crosslinking catalyst (manufactured by Nippon Chemical Industries, Ltd., trade name: Nacem Fe(III)), and Irganox1010 ( BASF) 0.5 parts by weight, 30 parts by weight of isopropyl myristate as a fatty acid ester (manufactured by Kao, trade name: Exceparl IPM) as a wettability additive, 210 parts by weight of ethyl acetate as a diluting solvent, using The disperser was stirred to obtain a urethane-based adhesive solution (adhesive composition).

[Production of optical surface protective film] The above-mentioned urethane-based adhesive composition was coated on a polyethylene terephthalate film (trade name: Diafoil T100G38, a base material with an antistatic treatment layer) The surface opposite to the antistatic treated surface (manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) was heated at 130° C. for 1 minute to form an adhesive layer with a thickness of 20 μm. Then, the polysiloxane-treated surface of the isolation film (polysiloxane-treated polyethylene terephthalate film with a thickness of 25 μm on one side) was attached to the surface of the above-mentioned adhesive layer, thereby producing an optical fiber. Surface protection film.

Table 1 and Table 2 show the results of the above-mentioned preparation contents and various measurements and evaluations regarding the surface protection films for optics with a separator of Examples and Comparative Examples. In addition, the compounding quantity in Table 1 represents an active ingredient.

[Table 1]

The details of the abbreviations in Table 1 above are as follows. <Substrate> Diafoil T100G38: thickness 38 μm, manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil T100G38 Diafoil T100G12: thickness 12 μm, manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil T100G12 SRF: thickness 80 μm, manufactured by Toyobo Corporation, trade name : SRF

<Ultraviolet absorber> Tinosorb S: 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3 , 5-Tris𠯤, trade name: Tinosorb S, manufactured by BASF, number of hydroxyl groups: 2) Tinuvin 571: 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl Phenol, manufactured by BASF, trade name: Tinuvin 571, number of hydroxyl groups: 1) Tinuvin 384-2: phenylpropionic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylene) ethyl)-4-hydroxy (C _7-9 side chain and straight-chain alkyl) ester compound, manufactured by BASF, trade name: Tinuvin _384-2 , number of hydroxyl groups: 1) Tinuvin 326: 2-[5- Chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol, manufactured by BASF, trade name: TINUVIN326, number of hydroxyl groups: 1) KEMISORB 111: 2,2 '-Dihydroxy-4-methoxybenzophenone, manufactured by Chemipro Chemical Co., Ltd., trade name: KEMISORB 111, number of hydroxyl groups: 2) SEESORB 106: 2-hydroxy-4-methoxybenzophenone, SHIPRO Manufactured by Kasei Corporation, trade name: SEESORB 106, number of hydroxyl groups: 4) <Antioxidant> Irganox1010: Pentaerythritol tetrakis[3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate ], manufactured by BASF, trade name: Irganox1010 <Wetting additive> Isopropyl myristate, manufactured by Kao, trade name: Exceparl IPM

[Table 2]

From the above-mentioned Table 2, it was confirmed that in all the examples, the hue change was suppressed, the UV curing was prevented, and the increase in the adhesive force after heating could be prevented. On the other hand, in Comparative Example 1, the ultraviolet transmittance was slightly high, and the deterioration prevention during ultraviolet irradiation was insufficient. In Comparative Example 2, the ultraviolet absorber used has more hydroxyl groups, and the change rate of the adhesive force before and after heating is large, which leads to heavy peeling and is not suitable for light peeling purposes. In Comparative Example 3, since no ultraviolet absorber was used, Therefore, it was confirmed that the transmittance of ultraviolet rays was very high, and it was not suitable for use in materials (members) for preventing ultraviolet rays from curing (absorbing). [Industrial Availability]

The optical surface protective film disclosed here is suitable for use in the manufacture and transportation of optical members used as constituent elements of liquid crystal display panels, plasma display panels (PDP), organic electroluminescence (EL) displays, and the like. A surface protective film to protect the optical member. Especially as polarizers, wave plates, retardation plates, optical compensation films, brightness enhancement films, light diffusion sheets, reflective sheets and other optical components for liquid crystal display panels, or as surface protection for optical components such as glass for displays Membranes are more useful.

Claims (5)

An optical surface protective film, characterized in that it is a base material formed of a polyester resin, and an adhesive layer formed of an adhesive composition provided on one side of the base material, wherein the adhesive The agent composition contains a base polymer and an ultraviolet absorber, the base polymer is a (meth)acrylic polymer or a urethane polymer, the b* value of the surface protection film is 2 or less, and the surface protection The transmittance of the film at a wavelength of 365 nm is 2% or less. After the adhesive layer is attached to the glass, the adhesive force before heating is 0.2N/25mm or less. After the adhesive layer is attached to the glass, the temperature is 100°C. The change rate of the adhesive force after heating for 30 minutes relative to the adhesive force before heating is ±30% or less. The optical surface protective film of claim 1, wherein the number of hydroxyl groups in the molecule of the ultraviolet absorber is 3 or less. The optical surface protective film according to claim 1 or 2, wherein the adhesive composition contains 0.1 to 20 parts by weight of the ultraviolet absorber relative to 100 parts by weight of the base polymer. The optical surface protective film of claim 1 or 2, wherein the thickness of the substrate is 6-100 μm, and the thickness of the adhesive layer is 1-30 μm. The optical surface protection film of claim 3, wherein the thickness of the substrate is 6-100 μm, and the thickness of the adhesive layer is 1-30 μm.