CN108624252A - Surface protection film - Google Patents

Abstract

The present invention relates to surface protection films. The present invention provides a surface protection film for optics that has a low transmittance of ultraviolet rays, suppresses changes in color tone, and is excellent in stability of adhesive force. The optical surface protection film of the present invention has a substrate formed of a polyester resin and an adhesive layer formed of an adhesive composition provided on one side of the substrate, wherein the surface protection The b* value of the film is 2 or less, the transmittance at the wavelength of 365 nm of the surface protection film is 2% or less, and the bonding after the adhesive layer is attached to the glass and heated at 100° C. for 30 minutes The rate of change in force from the adhesive force before heating was ±30% or less.

Description

surface protection film

technical field

The present invention relates to a surface protective film for optics. In particular, it is used to protect the surface of optical members (such as polarizing plates for liquid crystal displays, wave plates, retardation plates, optical compensation films, reflective sheets, brightness enhancement films, protective glasses for displays, etc.), and to protect them from ultraviolet rays. On the other hand, a surface protection film for optics is useful for protecting members that are prone to deterioration and the like from ultraviolet rays.

Background technique

A protective film generally has a structure in which an adhesive layer is provided on a film-form base material. The protective film is used for the purpose of bonding it to an optical member as an adherend via the adhesive layer, thereby protecting the optical member from surface damage during processing, transportation, inspection, etc. , stains. 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 layer (patent document 1).

Since the protective film may be subjected to visual inspection or the like in a state of being bonded to an optical member or the like, it is required to prevent color change (discoloration such as reddening) of the protective film over time.

In addition, since the liquid crystal enclosed in the liquid crystal cell used in the panel of the liquid crystal display is degraded by ultraviolet rays, a protective film having an ultraviolet absorbing function is attached and used on a member such as a polarizing plate attached to the liquid crystal cell.

In addition, in recent years, in the manufacture of cover glasses for mobile terminals such as thinned smartphones and tablet PCs, resins that are cured by active energy such as ultraviolet rays and heat have been used for lamination. In order to protect components degraded by ultraviolet rays, protective films containing ultraviolet absorbers are used.

The protective film used will be peeled and removed when the protective film is no longer needed, but when peeling and removing the protective film attached to the protective glass used in thinned smartphones, etc. It is difficult to easily peel and remove the protective film whose resultant force is increased, and damage or the like of the protective glass may be caused.

prior art literature

patent documents

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

Contents of the invention

The problem to be solved by the invention

Therefore, the inventors of the present invention conducted intensive studies in view of the above circumstances, and as a result, an object of the present invention is to provide an optical surface protection film having a low ultraviolet transmittance, suppressing a change in color tone, and excellent in adhesive force stability.

means of solving problems

That is, the optical surface protection film of the present invention has 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, and the optical surface protection film of the present invention The protective film is characterized in that the b* value of the surface protective film is 2 or less, the transmittance of the surface protective film at a wavelength of 365 nm is 2% or less, and after the adhesive layer is pasted on the glass, the The change rate of the adhesive force after heating at 100° C. for 30 minutes with respect to the adhesive force before heating was ±30% or less.

In the surface protection film for optics of this invention, it is preferable that the said adhesive composition contains a ultraviolet absorber.

In the surface protection film for optics of the present invention, it is preferable that the number of hydroxyl groups in the molecule of the ultraviolet absorber is three or less.

In the surface protection film for optics of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a (meth)acrylic polymer and/or a polyurethane-based polymer as a base polymer.

In the optical surface protection film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains 0.1 to 20 parts by weight of the ultraviolet absorber with respect to 100 parts by weight of the base polymer.

In the surface protection film for optics of the present invention, it is preferable that the substrate has a thickness of 6 μm to 100 μm, and the adhesive layer has a thickness of 1 μm to 30 μm.

The present invention is useful because it is possible to obtain a surface protection film for optics that has a low transmittance of ultraviolet rays, suppresses changes in color tone, and is excellent in adhesive force stability by using a surface protection film having specific optical characteristics.

Detailed ways

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

＜Overall structure of optical surface protection film＞

The surface protection film for optics disclosed here (hereinafter, sometimes simply referred to as "surface protection film") is one in which the surface of an adhesive layer in the form of an adhesive tape, adhesive label, or adhesive film is generally protected by a separator. The film is particularly suitable as a surface protection film for protecting the surface of optical components (for example, optical components used as components of liquid crystal display panels such as polarizing plates, wave plates, and cover glasses) during processing, inspection, and transportation. The adhesive layer in the surface protection film is typically formed continuously, but is not limited to such a form. For example, the adhesive layer may be formed in a regular or irregular pattern such as dots or stripes. In addition, the surface protective film disclosed here may be in the form of a roll, or may be in the form of a sheet (leaf-shaped).

＜Substrate＞

The surface protection film for optics of this invention has the base material which consists of polyester resins, It is characterized by the above-mentioned. The base material formed of the polyester resin has excellent properties such as optical properties and dimensional stability, which are preferable as a base material for a surface protection film.

Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, etc., which are based on A base material composed of a polyester-based polymer material (polyester resin) having a main skeleton of an ester bond as a main resin component (the main component of the resin component, typically accounting for 50% by weight or more) is used as the base material. Substrate. As other resin materials other than the above-mentioned polyester resins, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; polyethylene, polypropylene, cyclic or norbornan Examples of the resin material include olefin-based polymers such as polyolefins and ethylene-propylene copolymers; vinyl chloride-based polymers; and amide-based polymers such as nylon 6, nylon 6,6, and aromatic polyamide. Other examples of the resin material include imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol Polymers, vinylidene chloride polymers, vinyl butyral polymers, aryl ester polymers, polyoxymethylene polymers, epoxy polymers, etc. A substrate comprising a blend of two or more of the aforementioned polymers is also possible.

Various additives such as antioxidants, ultraviolet absorbers, plasticizers, colorants (pigments, dyes, etc.) can be blended as necessary into the resin material constituting the base material. 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, a treatment for improving the adhesiveness between the substrate and the adhesive layer (anchorability of the adhesive layer).

As the base material, a base material subjected to antistatic treatment can also be used. By using such a substrate, it is possible to suppress the charging of the surface protection film itself at the time of peeling, which is preferable. In addition, by subjecting the base material to antistatic treatment, it is possible to obtain a base material excellent in antistatic ability to an adherend while reducing the charge of the surface protection film itself. It should be noted that, as the method of imparting antistatic function, there is no particular limitation, existing known methods can be used, for example: coating antistatic resin containing antistatic agent and resin component, conductive polymer, containing A method of conductive resin for conductive substances; a method of vapor deposition or plating of conductive substances, and a method of kneading antistatic agents, etc.

The thickness of the base material is preferably 6 μm to 100 μm, more preferably 10 μm to 60 μm, even more preferably 15 μm to 40 μm. When the thickness of the base material is within the above-mentioned range, it is preferable because of excellent adhesion workability to an adherend, peelability and workability from an adherend.

The surface protection film disclosed here can also be implemented by including other layers besides a base material and an adhesive layer. As said other layer, the primer layer (anchor layer) etc. which improve the anchorability of an antistatic layer and an adhesive layer are mentioned. In addition, a separator may be pasted for the purpose of protecting the surface of the pressure-sensitive adhesive layer.

＜Adhesive layer＞

The surface protection film for optics of this invention is formed by providing the adhesive layer which consists of an adhesive composition on one side of the said base material, It is characterized by the above-mentioned. The adhesive layer used in the present invention is not particularly limited as long as it is formed of an adhesive composition containing an adhesive polymer having adhesive properties. As the adhesive composition, for example, an acrylic adhesive, a polyurethane adhesive, a synthetic rubber adhesive, a natural rubber adhesive, a polysiloxane adhesive, a poly Among the ester-based adhesives, it is preferable to use an adhesive composition containing a (meth)acrylic polymer and/or a polyurethane-based polymer as the base polymer.

＜Acrylic adhesive＞

When an acrylic adhesive is used for the adhesive layer, a (meth)acrylic polymer, which is an adhesive polymer constituting the acrylic adhesive, is used as a base polymer, and a (meth)acrylic polymer constituting the acrylic adhesive is As a raw material monomer of the base polymer, a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used as a main monomer. As the (meth)acrylic monomer, one kind or two or more kinds 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 (protected body) to be low, and it is possible to A surface protection film excellent in light peelability and re-peelability was obtained. It should be noted that (meth)acrylic polymers in the present invention refer to acrylic polymers and/or methacrylic polymers, and (meth)acrylates refer to acrylate and/or methacrylic polymers. Acrylate.

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, (meth) n-butyl acrylate, sec-butyl (meth)acrylate, tert-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-butyl (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 having an alkyl group with 4 to 14 carbon atoms, such as n-dodecyl acrylate, n-tridecyl (meth)acrylate, and n-tetradecyl (meth)acrylate class monomers as suitable monomers. In particular, by using a (meth)acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it is easy to control the release force (adhesive force) to the adherend to be low, and it becomes an adhesive with excellent re-peelability. mixture layer.

In particular, a (meth)acrylic polymer having an alkyl group having 1 to 14 carbon atoms is preferably contained in an amount of 65% by weight or more based on 100% by weight of the total amount of monomer components constituting the (meth)acrylic polymer. The monomer is more preferably 75% by weight or more, still more preferably 85% by weight to 99.9% by weight, particularly preferably 90% by weight to 99% by weight. When it is less than 65% by weight, the moderate wettability of the pressure-sensitive adhesive composition and the cohesion force of the pressure-sensitive adhesive layer deteriorate, which is not preferable.

In addition, the (meth)acrylic polymer may use a hydroxyl group-containing (meth)acrylic monomer as a raw material monomer. The hydroxyl group-containing (meth)acrylic monomers may be used singly or in combination of two or more. By using the hydroxyl group-containing (meth)acrylic monomer, it is easy to control the crosslinking of the adhesive composition, etc., and it is easy to control the improvement of wettability by flow and the peeling force at the time of peeling (adhesion). force) of the reduced balance.

As the hydroxyl group-containing (meth)acrylic monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxypropyl (meth)acrylate, Hydroxybutyl, 6-Hydroxyhexyl (meth)acrylate, 8-Hydroxyoctyl (meth)acrylate, 10-Hydroxydecyl (meth)acrylate, 12-Hydroxylauryl (meth)acrylate, Acrylic acid ( 4-hydroxymethylcyclohexyl)methyl ester, N-methylol(meth)acrylamide and the like.

The hydroxyl group-containing (meth)acrylic monomer is preferably contained in an amount of 25% by weight or less, more preferably 15% by weight, based on 100% by weight of the total monomer components constituting the (meth)acrylic polymer. Below, it is more preferably 0.1% by weight to 10% by weight, particularly preferably 1% by weight to 5% by weight. When it exists in the said range, it becomes easy to control the balance of the wettability of an adhesive composition, and the cohesive force of the adhesive layer obtained, and it is preferable.

In addition, as other polymerizable monomer components, for the reason that it is easy to obtain a balance of adhesive performance, within the range that does not impair the effect of the present invention, it can be used to adjust the glass transition temperature of the (meth)acrylic polymer. A polymerizable monomer such that Tg is 0°C or lower (usually -100°C or higher), a polymerizable monomer for adjusting peelability, and the like.

In addition, the (meth)acrylic polymer may use a carboxyl group-containing (meth)acrylic monomer as a raw material monomer. By using the carboxyl group-containing (meth)acrylic monomer, it is possible to suppress the increase in the adhesive force of the adhesive layer (surface protection film) over time, re-peelability, anti-adhesive force increase, and workability. excellent. Moreover, since it is excellent not only in the cohesive force of an adhesive layer but also in a shear force, it is preferable.

Examples of the carboxyl group-containing (meth)acrylic monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and the like.

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

In addition, as the (meth)acrylic polymer, other polymerizable monomers other than the above-mentioned raw material monomers can be used without particular limitation as long as the characteristics of the present invention are not impaired. For example, as the other polymerizable monomers, components that improve cohesion and heat resistance such as cyano group-containing monomers, vinyl ester monomers, and aromatic vinyl monomers; amide group-containing monomers can be suitably used; Body, imide-containing monomers, amino-containing monomers, epoxy-containing monomers, N-acryloylmorpholine, vinyl ether monomers, etc. improve the peeling force (adhesive force) or have a Components with functional groups acting as cross-linking bases. Among them, nitrogen-containing monomers such as cyano group-containing monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, and N-acryloylmorpholine are preferably used. By using a nitrogen-containing monomer, it is possible to secure a moderate peel force (adhesive force) that does not cause warping, peeling, etc., and to obtain a surface protection film excellent in shear force, which is useful. These polymerizable monomers can be used singly or in combination of two or more.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N- Dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylamino Propyl acrylamide, N,N-dimethylaminopropyl methacrylamide, diacetone acrylamide, etc.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide. Wait.

As the amino group-containing monomer, for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, Methylaminopropyl Etc.

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

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether, and the like.

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% by weight, more preferably 0 to 10% by weight, based on 100% by weight of the total monomer components constituting the (meth)acrylic polymer. %. The other polymerizable monomers may be appropriately adjusted in order to obtain desired properties.

The (meth)acrylic polymer may further contain an alkylene oxide group-containing reactive monomer as a monomer component.

In addition, from the viewpoint of compatibility with oxyalkylene-containing compounds, the average addition mole number of oxyalkylene units of the reactive monomer containing an alkylene oxide group is preferably 1 to 40, more preferably 3-40, still more preferably 4-35, particularly preferably 5-30. When the average added mole number is 1 or more, the effect of reducing contamination of an adherend (protected body) tends to be efficiently obtained. In addition, when the average added mole number is greater than 40, the interaction with the oxyalkylene group-containing compound is large, and the viscosity of the adhesive composition tends to increase, making application difficult, so it is not preferable. . It should be noted that the terminal of the oxyalkylene chain may be a hydroxyl group as it is, or may be substituted with another functional group or the like.

The reactive monomer containing the alkylene oxide group can be used alone, or two or more kinds can be used in combination. The overall content of the reactive monomer containing the alkylene oxide group is in the Based on the total amount of monomer components of the acrylic polymer, it is preferably 0 to 20% by weight, more preferably 0 to 10% by weight. When the content of the alkylene oxide group-containing reactive monomer exceeds 20% by weight, it is not preferable since the contamination property to the adherend will be deteriorated.

Examples of the oxyalkylene unit of the reactive monomer containing an alkylene oxide group include oxyalkylene units having an alkylene group having 1 to 6 carbon atoms, for example: Methylene, oxyethylene, oxypropylene, oxybutylene, etc. The hydrocarbon group of the oxyalkylene chain may be a straight chain or a branched chain.

In addition, it is more preferable that the reactive monomer containing an alkylene oxide group is a reactive monomer having an ethylene oxide group (Echelen Oxidide group). By using (meth)acrylic polymers containing reactive monomers with ethylene oxide groups as base polymers, the compatibility of the base polymers with oxyalkylene-containing compounds is improved, suitably suppressing Bleeding out to an adherend enables a low-contamination adhesive composition to be obtained.

Examples of reactive monomers containing alkylene oxide groups include (meth)acrylic acid alkylene oxide adducts, acryloyl groups, methacryloyl groups, allyl Reactive surfactants with reactive substituents such as radicals, etc.

Specific examples of the (meth)acrylic acid alkylene oxide adducts include, for example, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol - Polypropylene glycol (meth)acrylate, Polyethylene glycol-polybutylene glycol (meth)acrylate, Polypropylene glycol-polybutylene glycol (meth)acrylate, Methoxypolyethylene glycol (meth) ) acrylate, ethoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol (meth)acrylate, dodecyloxy Polyethylene glycol (meth)acrylate, octadecyloxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (methyl) ) acrylate, octyloxypolyethylene glycol-polypropylene glycol (meth)acrylate, etc.

In addition, specific examples of the reactive surfactant include, for example, anionic reactive surfactants having (meth)acryloyl or allyl groups, nonionic reactive surfactants, cationic Type reactive surfactants, etc.

The weight average molecular weight (Mw) of the (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 120. Ten thousand. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer to be obtained tends to be small, and glue residue tends to occur. On the other hand, when the weight-average molecular weight exceeds 5 million, the fluidity of the polymer is reduced, and there is insufficient wetting to the adherend (for example, a polarizing plate), and there is a problem of adhesion between the adherend and the surface protection film. The tendency of the cause of the swelling between the mixture layers. In addition, the weight average molecular weight means the molecular weight measured by GPC (gel permeation chromatography).

In addition, the glass transition temperature (Tg) of the (meth)acrylic polymer is preferably 0°C or lower, more preferably -10°C or lower (usually -100°C or higher). In the case where the glass transition temperature is higher than 0° C., the polymer is difficult to flow, for example, there is insufficient wetting of the polarizing plate as an optical member, and a gap occurs between the polarizing plate and the adhesive layer of the surface protection film. Tendency to cause uplift. In particular, by adjusting the glass transition temperature to -70° C. or lower, it is easy to obtain an adhesive layer excellent in wettability with respect to a polarizing plate and light peelability. In addition, the glass transition temperature of a (meth)acrylic polymer can be adjusted within the said range by suitably changing the monomer component used and a composition ratio.

The method of polymerizing the (meth)acrylic polymer is not particularly limited, and it can be polymerized by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. In view of characteristics such as low pollution of protected body), solution polymerization is a more preferable method. In addition, the obtained polymer may be any of random copolymers, block copolymers, alternating copolymers, graft copolymers, and the like.

＜Polyurethane adhesive＞

In the case where a polyurethane-based adhesive is used for the adhesive layer, any appropriate polyurethane-based adhesive may be employed. As such polyurethane-based adhesives, adhesive polymers obtained by reacting polyols and polyisocyanate compounds, that is, polyurethane-based polymers, as base polymers, are preferably used. As the adhesive, an adhesive containing a polyurethane resin obtained by curing a composition containing a polyol and a polyisocyanate compound can be used.

The lower limit of the content of the polyurethane resin in the polyurethane adhesive is preferably 40% by weight or more, more preferably 50% by weight or more, still more preferably 55% by weight or more, and still more preferably 60% by weight or more, particularly preferably 65% by weight or more, most preferably 70% by weight or more, as the upper limit, preferably 99.999% by weight or less, more preferably 99.99% by weight or less, further preferably 99.9% by weight or less, further It is preferably 99% by weight or less, particularly preferably 95% by weight or less, and most preferably 90% by weight or less. The polyurethane-based resin may be of only one type, or may be of two or more types.

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

Any appropriate polyol can be used as the polyol as long as it has two or more OH groups. Examples of such polyhydric alcohols include polyhydric alcohols (dihydric alcohols) having 2 OH groups, polyhydric alcohols (trihydric alcohols) having 3 OH groups, and polyhydric alcohols (tetrahydric alcohols) having 4 OH groups. Alcohols), polyols with 5 OH groups (pentaols), polyols with 6 OH groups (hexaols), etc.

In addition, as the polyol, a polyol (triol) having three OH groups can be preferably used. In this way, by using a polyol (trihydric alcohol) having 3 OH groups as the polyol, for example, an adhesive layer with a fast wetting speed can be made, and by combining with the specific substrate used in the present invention, it is possible to Provides a surface protection film with a higher detection rate of damage and impurities. The content ratio of the polyol (triol) having three OH groups in the polyol is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, still more preferably 80% by weight to 100% by weight %, more preferably 90% by weight to 100% by weight, particularly preferably 95% by weight to 100% by weight, and most preferably substantially 100% by weight.

As the polyol, preferably, a polyol having a number average molecular weight (Mn) of 400 to 20,000 may be included. The content ratio of the polyol having a number average molecular weight (Mn) of 400 to 20000 in the polyol is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, still more preferably 90% by weight to 100% by weight %, particularly preferably 95% by weight to 100% by weight, most preferably substantially 100% by weight.

In addition, in the present invention, it is preferable to use a polyol (triol) having three OH groups as a polyol in combination with 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 to 6,000. Trihydric alcohols with number average molecular weight (Mn) of 400 to 1900, more preferably trihydric alcohols with number average molecular weight (Mn) of 8000 to 15000 and ternary alcohols with number average molecular weight (Mn) of 2000 to 5000 Alcohol and a trihydric alcohol with a number average molecular weight (Mn) of 500 to 1800, more preferably a trihydric alcohol with a number average molecular weight (Mn) of 8000 to 12000, a trihydric alcohol with a number average molecular weight (Mn) of 2000 to 4000 and a number average A trihydric alcohol with a molecular weight (Mn) of 500-1500.

Examples of such polyols include polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols.

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

Examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6- Hexylene glycol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, tri Methylolpropane, 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, 1,14- Tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, Phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, their anhydrides, etc.

Examples of the polyether polyol include water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), dihydroxy Using benzene (catechol, resorcinol, hydroquinone, etc.) as an initiator, the addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide The obtained polyether polyol. Specifically, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. are mentioned, for example.

Examples of the polycaprolactone polyol include caprolactone-based polyester diol obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

As the polycarbonate polyol, for example, polycarbonate polyol obtained by polycondensation reaction of the above-mentioned polyol component and phosgene; , dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, dibenzyl carbonate and other carbonate diesters undergo transesterification Polycarbonate polyols obtained by condensation; Copolycarbonate polyols obtained by using two or more of the above-mentioned polyol components; Polycarbonate polyol; polycarbonate polyol obtained by etherification reaction of the above-mentioned various polycarbonate polyols with hydroxyl-containing compounds; transesterification reaction of the above-mentioned various polycarbonate polyols with ester compounds The obtained polycarbonate polyol; the polycarbonate polyol obtained by transesterifying the above-mentioned various polycarbonate polyols with hydroxyl-containing compounds; the above-mentioned various polycarbonate polyols and dicarboxylic acid compounds Polyester-based polycarbonate polyol obtained by polycondensation reaction; copolyether-based polycarbonate polyol obtained by copolymerizing the above-mentioned various polycarbonate polyols with alkylene oxides, and the like.

Examples of the castor oil-based polyol include castor oil-based polyols obtained by reacting castor oil fatty acid with the above-mentioned polyol component. Specifically, for example, a castor oil-based polyol obtained by reacting castor oil fatty acid with polypropylene glycol may be mentioned.

The said polyisocyanate compound (polyfunctional isocyanate compound) may be only 1 type, and may be 2 or more types.

As the polyisocyanate compound (polyfunctional isocyanate compound), any appropriate polyisocyanate compound that can be used in a urethane reaction can be employed. 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, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

Examples of the polyfunctional alicyclic isocyanate compound include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isofor Alone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, etc.

Examples of the polyfunctional aromatic diisocyanate compound include: phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, Isocyanate, 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 the above-mentioned various polyfunctional isocyanate compounds, biuret forms obtained by reacting with water, and polyisocyanurate rings. trimers, etc. In addition, these can also be used together.

The content 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 based on 100 parts by weight of the polyol.

The equivalent ratio of NCO groups to OH groups in the polyol and the polyisocyanate compound is preferably greater than 1.0 and less than or equal to 5.0 in terms of NCO groups/OH groups, more preferably 1.1 to 5.0, further preferably 1.2 to 4.0, especially Preferably it is 1.5-3.5, most preferably it is 1.8-3.0.

The polyurethane-based resin may contain fatty acid esters that can be used as wetting additives. Wetting speed can be improved by making polyurethane-type resin contain fatty acid ester. There may be only one kind of fatty acid ester, or two or more kinds thereof.

With respect to 100 parts by weight of the polyol, the content ratio of the fatty acid ester is preferably 5 parts by weight to 50 parts by weight, more preferably 10 parts by weight to 45 parts by weight, even more preferably 15 parts by weight to 40 parts by weight, Particularly preferably, it is 20 parts by weight to 35 parts by weight, and most preferably it is 25 parts by weight to 30 parts by weight. Wetting rate can be further improved by adjusting the content ratio of fatty acid ester to the said range. When the content ratio of fatty acid ester is too small, there exists a possibility that wetting speed may not fully improve. When the content ratio of the fatty acid ester is too large, there may be a problem that the cost is disadvantageous, that the adhesive property cannot be maintained, or that the adherend is contaminated.

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, most preferably 270-340. By adjusting the number average molecular weight (Mn) of the fatty acid ester to be within the above-mentioned range, the wetting rate can be further improved. When the number average molecular weight (Mn) of the fatty acid ester is too small, there is a possibility that the wetting speed may not increase even if the compounding amount is large. When the number-average molecular weight (Mn) of the fatty acid ester is too large, the curability of the adhesive during drying may deteriorate, which may adversely affect not only the wettability but also other adhesive properties.

As the fatty acid ester, any suitable fatty acid ester can be employed within a range not impairing the effect of the present invention. Examples of such fatty acid esters include polyethylene oxide bisphenol A laurate, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, glycerol mono Behenate, Cetyl 2-Ethylhexanoate, Isopropyl Myristate, Isopropyl Palmitate, Cholesteryl Isostearate, Lauryl Methacrylate, Coco Fatty Acid Methyl Ester, Methyl laurate, methyl oleate, methyl stearate, myristyl myristate, octyldodecyl myristate, pentaerythritol monooleate, pentaerythritol monostearate, pentaerythritol tetrapalmitate , stearyl stearate, isotridecyl stearate, triglyceride (2-ethylhexanoate), butyl laurate, octyl oleate, etc.

The polyurethane-based resin may contain a leveling agent. By containing a leveling agent in the urethane-based resin, uneven appearance due to orange peel wrinkles can be prevented. The leveling agent may be only one kind, or two or more kinds.

As a method of curing the composition containing the polyol and the polyisocyanate compound to obtain a polyurethane resin, a method of urethane reaction using bulk polymerization, solution polymerization, etc. can be used within the range that does not impair the effect of the present invention. Any suitable method within . However, conventional polyurethane-based resins obtained through so-called urethane prepolymers may not be able to exhibit the effects of the present invention. As a method, methods other than the method of obtaining a polyurethane-based resin via a urethane prepolymer are preferable.

＜UV absorbers＞

In the surface protection film for optics of the present invention, the pressure-sensitive adhesive composition preferably contains an ultraviolet absorber, and the ultraviolet absorber preferably has three or less hydroxyl groups in a molecule. By using an ultraviolet absorber, members easily degraded by ultraviolet rays can be protected, and furthermore, by using an ultraviolet absorber having three or less hydroxyl groups, the adhesive force of the adhesive layer is excellent in stability, so it is preferable. In addition, it is presumed that when the number of hydroxyl groups in the molecule of the ultraviolet absorber is large, the ultraviolet absorber reacts with the crosslinking agent and inhibits curing of the adhesive composition.

The ultraviolet absorber is not particularly limited, and examples thereof include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, hydroxybenzophenone-based ultraviolet absorbers, salicylic acid An ester type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, etc. can be used individually by 1 type or in combination of 2 or more types. Among them, an embodiment in which the number of hydroxyl groups in the molecule of the ultraviolet absorber is three or less is a more preferable embodiment.

As a triazine-based ultraviolet absorber having three or less hydroxyl groups in one molecule, specifically, 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}benzene can be used base]-6-(4-methoxyphenyl)-1,3,5-triazine (TinosorbS, manufactured by BASF); 2,4-bis[2-hydroxy-4-butoxyphenyl ]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN 460, manufactured by BASF); 2-(4,6-bis(2,4-dimethylbenzene base)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C ₁₀ -C ₁₆ (mainly C ₁₂ -C ₁₃ )alkyloxy)methyl]oxirane The reaction product of alkanes (TINUVIN400, manufactured by BASF); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3- (dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 , the reaction product of 3,5-triazine and 2-ethylhexyl glycidate (TINUVIN405, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl )-5-[(hexyl)oxy]phenol (TINUVIN1577, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-( 2-Ethylhexanoyloxy)ethoxy]phenol (ADK STAB LA46, manufactured by ADEKA); 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]benzene base)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF Corporation) and the like.

As the benzotriazole UV 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 manufacturing), phenylpropionic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyl (C _7-9 side chain and straight chain alkanes base) 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-tetramethyl Butyl)phenol (TINUVIN928, manufactured by BASF); Methyl-3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene The reaction product of diol 300 (TINUVIN1130, manufactured by BASF); 2-(2H-benzotriazol-2-yl) p-cresol (TINUVIN P, manufactured by BASF); 2-(2H-benzotriazole-2- base)-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), (TINUVIN326FL, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol (TINUVIN328 , manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN329, manufactured by BASF); methyl 3-( The reaction product of 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-hydroxyl-3-(3,4,5,6-tetrahydro-o- Phthalimidomethyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Industries) and the like.

Examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and hydroxybenzophenone-based ultraviolet absorbers (hydroxybenzophenone-based compounds) include, for example, 2,4-diphenone Hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous salt and trihydrate salt), 2- Hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone (KEMISORB 111, manufactured by Chemipro Chemicals), etc.

Examples of the salicylate-based ultraviolet absorber (salicylate-based compound) include phenyl 2-acryloyloxybenzoate, 2-acryloyloxy-3-methylbenzoic acid Phenyl ester, 2-acryloyloxy-4-methylbenzoic acid phenyl ester, 2-acryloyloxy-5-methylbenzoic acid phenyl ester, 2-acryloyloxy-3-methoxybenzoic acid phenyl Esters, 2-hydroxyphenylbenzoate, 2-hydroxy-3-methylbenzoate, 2-hydroxy-4-methylbenzoate, 2-hydroxy-5-methylbenzoate, 2 -Hydroxy-3-methoxyphenylbenzoate, 3,5-di-tert-butyl-4-hydroxybenzoic acid 2,4-di-tert-butylphenyl (TINUVIN120, manufactured by BASF) and the like.

Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include: 2-alkyl cyanoacrylate, 2-cycloalkyl cyanoacrylate, 2-cyanoacrylate Alkoxyalkyl esters, alkenyl 2-cyanoacrylates, alkynyl 2-cyanoacrylates, and the like.

The ultraviolet absorber may be used alone or in combination of two or more. The total content of the ultraviolet absorber is preferably 0.1 to 20 parts by weight, more preferably 0.5 parts by weight, relative to 100 parts by weight of the base polymer. It is a weight part - 15 weight part, More preferably, it is 1 weight part - 10 weight part. By setting the content of the ultraviolet absorber within the above-mentioned range, the ultraviolet absorbing function of the pressure-sensitive adhesive layer can be fully exhibited and the ultraviolet polymerization is not hindered, so it is preferable.

＜Antioxidant＞

In the optical surface protection film of the present invention, the adhesive composition may contain an antioxidant, and examples thereof include radical chain terminators (radical chain inhibitors), peroxide decomposers, and the like.

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

Examples of the peroxide decomposing agent include sulfur-containing antioxidants and phosphorus-containing antioxidants.

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

Examples of the monophenol antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, β -(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, etc.

Examples of the bisphenol antioxidants include 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4- ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylenebis(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.

Examples of the polymeric phenolic antioxidant include: 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5 -Trimethyl-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)butyrate]ethylene glycol, 1,3,5- Tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, tocopherol, pentaerythritol tetrakis[3-(3 ',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] and so on.

Examples of the sulfur-containing antioxidant include: dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, 3,3'-thiodipropionate Distearyl dipropionate, etc.

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

The antioxidant may be used alone or in combination of two or more. The overall content of the antioxidant is preferably 0.01 to 1 part by weight, more preferably 0.1 part by weight, relative to 100 parts by weight of the base polymer. ~0.8 parts by weight, more preferably 0.2 parts by weight to 0.7 parts by weight. By setting the content of the antioxidant within the above-mentioned range, deterioration due to oxidation of the pressure-sensitive adhesive layer can be sufficiently suppressed, and the adhesive properties are stabilized, which is preferable.

＜Oxyalkylene-containing compounds＞

The adhesive composition used in the present invention may contain an oxyalkylene group-containing compound. By containing an oxyalkylene group-containing compound, light peelability can be further expressed. Examples of the oxyalkylene-containing compound include organopolysiloxanes having an oxyalkylene chain, and oxyalkylene-containing compounds excluding organopolysiloxane.

＜Crosslinking agent＞

In the surface protection film of the present invention, it is preferable that the adhesive composition contains a crosslinking agent. Moreover, in this invention, the said adhesive composition can be used as an adhesive layer. For example, when the adhesive composition is an acrylic adhesive containing the (meth)acrylic polymer, by appropriately adjusting the constituent units of the (meth)acrylic polymer, The composition ratio, the selection of the crosslinking agent, the addition ratio, and the like can be crosslinked to obtain a pressure-sensitive adhesive layer (surface protection film) that is more excellent in heat resistance. In addition, in the case of a polyurethane-based adhesive containing the above-mentioned polyurethane-based polymer, it is possible to obtain an initial An adhesive layer (surface protection film) that is excellent in reworkability (reworkability) and excellent in adhesion reliability over time.

As the crosslinking agent used in the present invention, isocyanate compounds, epoxy compounds, melamine-based resins, aziridine derivatives, and metal chelate compounds can be used. In particular, it is preferable to use isocyanate compounds and epoxy compounds. The way. In addition, these compounds may be used alone or in combination of two or more.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), and dimer acid diisocyanate; Cycloaliphatic isocyanates such as isocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane; 2,4-toluene diisocyanate, 4 , 4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI) and other aromatic isocyanates; using allophanate bond, biuret bond, isocyanurate bond, uretdione bond (ウレトジオン bond), urea bond, carbodiimide bond, uretonimine bond (ウレトンイミン bond), A modified polyisocyanate obtained by modifying the above-mentioned isocyanate compound with a diazinetrione bond or the like. Examples of commercially available products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (the above are manufactured by Mitsui Chemicals), Sumidule T80, Sumidule L, Desmodur N3400 (the above, Sumika Bayer Polyurethane (Sumika Bayer Urethane), 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 in combination of two or more, and a difunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a crosslinking agent in combination, both adhesiveness and repulsion resistance (adhesion to a curved surface) can be achieved, and an adhesive layer (surface protection film) having better adhesion reliability can be obtained.

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

Hexamethylolmelamine etc. are mentioned as said melamine resin. Examples of the aziridine derivatives include commercially available products under the trade names HDU, TAZM, and TAZO (the above are manufactured by Mutual Pharmaceutical Co., Ltd.).

As the metal chelate compound, examples of metal components include aluminum, iron, tin, titanium, nickel, and the like; and examples of chelate components include acetylene, methyl acetoacetate, ethyl lactate, and the like.

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, based on 100 parts by weight of the (meth)acrylic polymer. parts, more preferably 0.5 to 10 parts by weight, most preferably 1 to 8 parts by weight. When the content is less than 0.01 parts by weight, the formation of crosslinks by the crosslinking agent becomes insufficient, and there is a tendency that the cohesive force of the obtained adhesive layer becomes small, and sufficient heat resistance may not be obtained. , and become the cause of glue residue. On the other hand, when the content is more than 20 parts by weight, the cohesive force of the polymer is large, the fluidity is lowered, and there is a tendency that the wetting of the adherend (for example, a polarizing plate) is insufficient, and the adhesion between the adherend and the adherend tends to be insufficient. The cause of swelling generated between adhesive layers (adhesive composition layers). In addition, these crosslinking agents may be used alone or in combination of two or more. In addition, in the case of the polyurethane-based adhesive containing the polyurethane-based polymer, the content of the cross-linking agent is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the polyol, more preferably 5 parts by weight to 28 parts by weight, more preferably 5 parts by weight to 25 parts by weight, particularly preferably 5 parts by weight to 23 parts by weight. By adjusting the content of the crosslinking agent within the above-mentioned range, the obtained pressure-sensitive adhesive layer is excellent not only in initial adhesiveness but also in adhesion reliability over time when sticking to an adherend.

＜Crosslinking catalyst＞

The adhesive composition may further contain a cross-linking catalyst for more efficiently performing any of the above-mentioned cross-linking reactions. As the crosslinking catalyst, for example, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate (dioctyltin dilaurate); tri(acetylacetonate)iron, tri(hexane -2,4-diketone)iron, tris(heptane-2,4-diketone)iron, tris(heptane-3,5-diketone)iron, tris(5-methylhexane- 2,4-diketone)iron, tris(octane-2,4-diketone)iron, tris(6-methylheptane-2,4-diketone)iron, tris(2,6- Dimethylheptane-3,5-diketonate)iron, Tris(nonane-2,4-diketonate)iron, Tris(nonane-4,6-diketonate)iron, Tris(2, 2,6,6-Tetramethylheptane-3,5-dione)iron, Tris(tridecane-6,8-dione)iron, Tris(1-phenylbutane-1,3 -diketo)iron, tris(hexafluoroacetylacetonate)iron, tris(ethylacetoacetate)iron, tris(n-propylacetoacetate)iron, tris(isopropylacetoacetate)iron, tris(acetoacetate)iron n-butyl) iron, tris(sec-butyl acetoacetate) iron, tris(tert-butyl acetoacetate) iron, tris(methyl propionyl acetate) iron, tris(ethyl propionyl acetate) iron, tris(propionyl n-Propyl acetate) iron, tris (isopropyl propionyl acetate) iron, tris (n-butyl propionyl acetate) iron, tris (sec-butyl propionyl acetate) iron, tris (tert-butyl propionyl acetate) iron , Tris(benzyl acetoacetate) iron, tris(dimethyl malonate) iron, tris(diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, Iron catalysts such as ferric chloride. These crosslinking catalysts may be used alone or in combination of two or more.

The content of the crosslinking catalyst is not particularly limited, for example, it is preferably set at about 0.0001 parts by weight to about 1 part by weight, more preferably 0.001 parts by weight to 0.5 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer. parts by weight. When it exists in the said range, the speed of a crosslinking reaction at the time of forming an adhesive layer will be quick and the pot life of an adhesive composition will also become long, and it is a preferable aspect. In addition, only one kind may be used, or two or more kinds may be used. In addition, in the case of the polyurethane adhesive containing the polyurethane polymer, the content of the crosslinking catalyst is preferably 0.01 to 1 part by weight based on 100 parts by weight of the polyol. , more preferably 0.08 to 0.5 parts by weight.

＜Other additives＞

In addition, within the range that does not impair the effects of the present invention, other known additives may be contained in the adhesive composition, for example, powders such as lubricants, colorants, pigments, etc. may be appropriately added according to the intended use. Solvents, plasticizers, softeners, tackifiers, low molecular weight polymers, surface lubricants, leveling agents, wetting additives, antioxidants, corrosion inhibitors, light stabilizers, heat-resistant stabilizers, UV absorbers , polymerization inhibitors, silane coupling agents, antistatic agents, inorganic or organic fillers, metal powders, granules, foils, etc.

＜Optical surface protection film＞

The optical surface protection film (surface protection film) of the present invention has a substrate comprising a polyester resin and an adhesive layer formed of an adhesive composition provided on one side of the substrate. In this case, the adhesive The crosslinking of the mixture composition is usually carried out after application of the adhesive composition, but the adhesive layer including the crosslinked adhesive composition may be transferred onto 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 produced by applying the adhesive composition (solution) on the substrate, drying and removing the polymerization solvent, etc. An adhesive layer is formed on the substrate. Thereafter, curing may be performed for the purpose of adjusting component migration of the adhesive layer, adjusting crosslinking reaction, and the like. In addition, when the adhesive composition is coated on the substrate to form a surface protection film, one or more solvents other than the polymerization solvent may be newly added to the adhesive composition so that the adhesive composition can be coated uniformly. cloth on the substrate.

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

The thickness of the adhesive layer is preferably 1 μm to 30 μm, more preferably 2 μm to 28 μm, and even more preferably 3 μm to 25 μm. When the thickness of the pressure-sensitive adhesive layer is in the above-mentioned range, it is easy to obtain a balance of moderate re-peelability and adhesiveness, which is preferable.

The surface protection film of the present invention preferably has a total thickness of 7 μm to 130 μm, more preferably 10 μm to 100 μm, further preferably 20 μm to 50 μm. When it is in the said range, adhesive characteristics (removability, adhesiveness, adhesive force stability, etc.), workability, and appearance characteristics are excellent, and it is a preferable embodiment. It should be noted that the total thickness refers to the sum of the thicknesses of all layers including the base material, the adhesive layer, the separator, and other layers.

＜Separator＞

The surface protection film of the present invention may, if necessary, bond a separator for the purpose of protecting the surface of the pressure-sensitive adhesive layer.

As a material constituting the separator, there are paper and a 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 adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentadiene films, and polymethylpentadiene films. Polyethylene film, 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 separator is usually about 5 μm to about 200 μm, preferably about 8 μm to about 100 μm, more preferably about 10 μm to about 50 μm. The spacer can also be subjected to mold release and antifouling treatment with polysiloxane, fluorine-containing, long-chain alkyl or fatty acid amide release agents, silica powder, etc., as required, or Anti-static treatment such as coating type, kneading type, evaporation type, etc.

The surface protection film disclosed here may be implemented in such a manner that it contains other layers in addition to the support and the adhesive layer. As said other layer, the primer layer (anchor layer) etc. which improve the anchorability of an antistatic layer and an adhesive layer are mentioned.

＜How to use optical surface protection film＞

As a method of using the optical surface protection film of the present invention, for example, the surface of the pressure-sensitive adhesive layer constituting the optical surface protection film of the present invention is bonded to the surface of a part of the printed part of the printed glass to perform ultraviolet curing. In the step, an ultraviolet curable resin is applied to the exposed portion where the optical surface protection film is not bonded, so as to prevent ultraviolet rays from deteriorating the portion where the optical surface protection film is bonded and where the ultraviolet curable resin is not applied. This method of use can protect members, such as printed parts, which are expected to be prevented from undergoing a curing reaction by ultraviolet irradiation and being degraded by ultraviolet irradiation.

＜Optical components＞

In the present invention, the surface of the pressure-sensitive adhesive layer of the optical surface protection film can be bonded to an optical member to protect the optical member. Even if the surface protection film is pasted and stored on an optical member as an adherend of an adhesive layer and then heated, it can prevent an increase in the adhesive force, has excellent adhesive force stability, and can be peeled off again. Since it can be used for the surface protection application (surface protection film) at the time of processing, transportation, shipment, etc. because it is excellent, it is useful for protecting the surface of the said optical member (polarizing plate etc.). In addition, since the change in the color tone of the adhesive layer constituting the surface protection film is suppressed, and the ultraviolet transmittance of the entire surface protection film is suppressed low, it is possible to inspect the surface protection film in a state where the surface protection film is bonded to the optical member. It is a preferred embodiment because it can be used in applications where it is desired to suppress curing and deterioration accompanying ultraviolet irradiation.

[Example]

Hereinafter, several examples related to the present invention will be described, but the present invention is not intended to be limited to the scope shown in the specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise indicated. In addition, the compounding quantity (addition quantity) in a table|surface is shown.

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

<Measurement of glass transition temperature (Tg) of acrylic polymer>

The glass transition temperature (Tg) (° C.) was obtained from the following formula using the following literature value as the glass transition temperature Tgn (° C.) of the homopolymer composed of each monomer.

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, Tgn (°C) represents the glass transition temperature of the homopolymer formed by each monomer, n Indicates the type of each monomer.)

Literature value:

2-ethylhexyl acrylate (2EHA): -70°C

2-Hydroxyethyl Acrylate (HEA): -15°C

In addition, reference is made to "Synthesis, design and development of new applications of acrylic resins (Synthesis, Design and Development of New Applications of Acryl Resin)" (published by the Central Management and Development Center Publishing Department) as a document value.

<Measurement of weight average molecular weight (Mw) of acrylic polymer>

The weight average molecular weight (Mw) of the (meth)acrylic polymer used was measured using the Tosoh Corporation GPC apparatus (HLC-8220GPC). The measurement conditions are as follows.

Sample concentration: 0.2% by weight (tetrahydrofuran (THF) solution)

Injection volume: 10μl

Eluent: tetrahydrofuran

Flow rate: 0.6ml/min

Measuring temperature: 40°C

column:

Sample column: TSKguardcolumn SuperHZ-H (1 piece) + TSKgel SuperHZM-H (2 pieces)

Reference column: TSKgel SuperH-RC (1 piece)

Detector: Differential Refractometer (RI)

In addition, the weight average molecular weight was calculated|required by the polystyrene conversion value. In addition, not limited to the acrylic polymer, the number average molecular weight (Mn) was also measured in the same manner as the weight average molecular weight (Mw).

<Measurement of b* value>

The optical surface protection film (surface protection film) of each example was cured at room temperature for 7 days, then cut into a size of 50 mm in width and 50 mm in length, and the separator was peeled off from the surface of the adhesive layer of the surface protection film, and then the The "b* value" was measured with an integrating sphere-type transmittance measuring instrument (manufactured by Murakami Color Technology Laboratory Co., Ltd., model "DOT-3C"). It should be noted that the b* value refers to the CIELab value.

The b* value of the surface protection film is 2 or less, preferably 1.6 or less, more preferably 1.2 or less. If the b* value is within the above range, it is possible to suppress the change in the color tone of the pressure-sensitive adhesive layer, and it is also possible to perform inspection in the state attached to the optical member, which is a level that does not cause problems in practical use, so it is preferable.

＜Measurement of Transmittance＞

Regarding the transmittance, using a spectrophotometer U-4100 manufactured by Hitachi Corporation, light with a wavelength of 300 nm to 400 nm is vertically incident on the surface of the substrate from the substrate side of the optical surface protection film obtained in Examples and Comparative Examples to obtain The transmittance (%) is shown. In addition, the transmittance (ultraviolet transmittance) shows the transmittance (%) at the time of wavelength 365nm among the transmittance|permeability to the light of the wavelength in the said range.

The transmittance is 2% or less, preferably 1.8% or less, more preferably 1.6% or less. When the transmittance is greater than 2%, the transmittance of ultraviolet rays is high, and curing and deterioration due to ultraviolet irradiation cannot be prevented, and problems such as a decrease in the strength of printed parts occur, which is not preferable.

＜Initial adhesion (adhesion before heating)＞

The surface protection film of each example was cut into a width of 25 mm, and the adhesive layer side of the surface protection film for optics after the separator was peeled off was bonded to a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., trade name: Micro) using a 2 kg roller. The surface of SlideGlass S) was left at room temperature (23°C, 50%RH) for 20 minutes, and then a tension-compression tester (device name "TG-1kN", manufactured by Minebea Corporation) was used at a peeling angle of 180° and a peeling speed of 0.3 Peeling was performed at m/min, and the peeling force (adhesion to glass) of the surface protection film was measured as "initial adhesive force (adhesive force before heating)" (N/25mm).

Measuring conditions: temperature: 23±2℃, humidity: 50±5%RH

＜Adhesive force after heating＞

Prepare a test piece in the same manner as the above-mentioned initial adhesion force, then heat at 100°C for 30 minutes, then leave it at room temperature (23°C, 50%RH) for 1 hour, and then The "adhesive force after heating" (N/25mm) was measured as follows.

The adhesion to glass is preferably 0.2 N/25 mm or less, more preferably 0.15 N/25 mm or less, and still more preferably 0.1 N/25 mm or less, both initially (before heating) and after heating. When the adhesive force is greater than 0.2N/25mm, the adhesive force becomes too high, which makes it difficult to achieve light peelability (repeelability). For example, when used as a surface protection film, it may be peeled off later. In some cases, adhesive residues are generated on the adherend or the base material is damaged, so it is not preferable.

<Rate of change in adhesive force before and after heating>

The change rate of the adhesive force before and after heating was calculated by the following formula.

(Change (%) of 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 rate of change exceeds ±30%, it is not preferable because heavy peeling and peeling problems are caused.

[Example 1]

[Preparation of Acrylic Polymer]

Put 200 parts by weight of 2-ethylhexyl acrylate (2EHA) and 8 parts by weight of 2-hydroxyethyl acrylate (HEA) into a four-necked flask with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, as a polymerization initiator 0.4 parts by weight of 2,2'-azobisisobutyronitrile, 312 parts by weight of ethyl acetate as a solvent, introducing nitrogen gas while stirring slowly, keeping the liquid temperature in the flask at about 65°C, and performing 6 Polymerization was carried out for 1 hour 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 Binder Solution]

The above-mentioned acrylic polymer solution (40% by weight) was diluted to 29% by weight with ethyl acetate, and isocyanurate of hexamethylene diisocyanate was added as a crosslinking agent with respect to 100 parts by weight of solid content in the solution. Ester form (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate HX, "C/HX" in Table 1) 4 parts by weight, dibutyltin dilaurate (Tokyo Fine Chemical Co., Ltd.) as a crosslinking catalyst Manufactured, 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-ethane Hexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name: Tinosorb S, manufactured by BASF) 2 parts by weight, relative to The total amount of the solvent was 3 parts by weight of acetylacetone as a crosslinking retarder, and mixed and stirred to obtain an acrylic adhesive solution (adhesive composition).

[Production of optical surface protection film]

The above-mentioned acrylic adhesive solution was coated on a polyethylene terephthalate film (trade name: Diafoil T100G38, manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) with an antistatic treatment layer as a base material. The surface opposite to the electrostatically treated surface was heated at 130° C. for 1 minute to form an adhesive layer with a thickness of 21 μm. Next, the silicone-treated surface of the separator (polyethylene terephthalate film with a thickness of 21 μm treated with silicone on one side) was attached to the surface of the above-mentioned pressure-sensitive adhesive layer, thereby Produced optical surface protection film.

<Examples 2 to 5, Comparative Examples 1 to 3>

Based on the compounding content shown in Table 1, the surface protection film for optics was produced by the method similar to Example 1.

<Examples 6 and 7>

Using a polyester film with a thickness of 12 μm (manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil T100G12) instead of the base material used in Example 1, an optical film was produced in the same manner as in Example 1 based on the composition shown in Table 1. Surface protection film.

<Examples 8 and 9>

Using a polyester film with a thickness of 80 μm (manufactured by Toyobo Co., Ltd., trade name: SRF) instead of the base material used in Example 1, an optical surface was produced by the same method as in Example 1 based on the composition shown in Table 1. protective film.

<Example 10>

[Preparation of Polyurethane Adhesive Solution]

As polyols, 85 parts by weight of PREMINOL S3011 (manufactured by Asahi Glass Co., Ltd., Mn=10000), 13 parts by weight of SANNIX GP3000 (manufactured by Sanyo Chemical Industries, Mn=3000), and 2 parts by weight of SANNIX GP1000 (manufactured by Sanyo Chemical Industries, Mn=1000) were used. Parts by weight, 10 parts by weight of Tinuvin 384-2 (manufactured by BASF) as a UV absorber, 18 parts by weight of a polyfunctional alicyclic isocyanate compound (manufactured by Tosoh, trade name: Coronate HX) as a crosslinking agent, Co-catalyst (manufactured by Nippon Chemical Industry Co., Ltd., trade name: Nacem Fe(III)) 0.08 parts by weight, 0.5 parts by weight of Irganox 1010 (manufactured by BASF) as an antioxidant, nutmeg as a fatty acid ester as a wetting additive 30 parts by weight of isopropyl ester (manufactured by Kao, trade name: Exceparl IPM) and 210 parts by weight of ethyl acetate as a diluting solvent were stirred with a disperser to obtain a polyurethane adhesive solution (adhesive composition ).

[Production of optical surface protection film]

The above-mentioned polyurethane adhesive composition is coated on a polyethylene terephthalate film (trade name: Diafoil T100G38, manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) with an antistatic treatment layer as a base material and The surface opposite to the antistatic treatment surface was heated at 130° C. for 1 minute to form an adhesive layer with a thickness of 20 μm. Next, the silicone-treated surface of the separator (polyethylene terephthalate film with a thickness of 25 μm treated with silicone on one side) was attached to the surface of the above-mentioned pressure-sensitive adhesive layer, thereby Produced optical surface protection film.

Table 1 and Table 2 show the above-mentioned composition content, various measurement and evaluation results of the surface protection films for optics with spacers of Examples and Comparative Examples. In addition, the compounding quantity in Table 1 shows an active ingredient.

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 Co., Ltd., trade name: SRF

＜UV absorbers＞

Tinosorb S: 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine , trade name: Tinosorb S, manufactured by BASF, hydroxyl number: 2)

Tinuvin 571: 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 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-dimethylethyl)-4-hydroxyl (C _7-9 side chain and straight 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-butylphenol, manufactured by BASF, trade name: TINUVIN326, number of hydroxyl groups: 1)

KEMISORB 111: 2,2'-dihydroxy-4-methoxybenzophenone, manufactured by Chemipro Chemicals, trade name: KEMISORB 111, number of hydroxyl groups: 2)

SEESORB 106: 2-Hydroxy-4-methoxybenzophenone, manufactured by Shipro Chemical Co., Ltd., trade name: SEESORB106, 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 Additives＞

Isopropyl myristate, manufactured by Kao, trade name: Exceparl IPM

From the above-mentioned Table 2, it can be confirmed that, in all the examples, the color tone change was suppressed, ultraviolet curing was prevented, and an increase in the adhesive force after heating was prevented. On the other hand, in Comparative Example 1, the ultraviolet transmittance was slightly high, and the deterioration prevention at the time of ultraviolet irradiation was insufficient. In Comparative Example 2, the UV absorber used had many hydroxyl groups, and the change rate of the adhesive force before and after heating was large, resulting in heavy peeling and was not suitable for light peeling applications. In Comparative Example 3, since no UV absorbing It was confirmed that the ultraviolet transmittance is very high, and it is not suitable for use as a material (member) intended to prevent ultraviolet curing (absorption).

Industrial applicability

The surface protection film for optics disclosed here is suitable for use as an optical member used as a constituent element of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, etc. during manufacture and transportation. The surface protection film which protects this optical member. In particular, it is useful as an optical surface protection film for optical components such as polarizing plates, wave plates, retardation plates, optical compensation films, brightness enhancement films, light diffusion sheets, and reflection sheets for liquid crystal display panels, or glass for displays. of.

Claims (6)

1. a kind of optics surface protection film, the list that there is the base material formed by polyester resin and be set to the base material The adhesive phase formed by adhesive composition in face, which is characterized in that

The b* values of the surface protection film be 2 hereinafter,

Transmissivity when the wavelength 365nm of the surface protection film be 2% hereinafter,

After described adhesive layer is pasted onto on glass, before bonding force after being heated 30 minutes at 100 DEG C is relative to heating Bonding force change rate be ± 30% or less.

2. optics surface protection film as described in claim 1, which is characterized in that described adhesive composition contains ultraviolet light Absorbent.

3. optics surface protection film as claimed in claim 2, which is characterized in that the intramolecular of the ultra-violet absorber Hydroxyl is 3 or less.

4. optics surface protection film according to any one of claims 1 to 3, which is characterized in that described adhesive combines Object contains (methyl) acrylic polymer and/or polyurethane polymer as basic polymer.

5. optics surface protection film as claimed in claim 4, which is characterized in that relative to 100 weight of the base polymer Part is measured, described adhesive composition contains the ultra-violet absorber of the parts by weight of 0.1 parts by weight~20.

6. such as optics surface protection film according to any one of claims 1 to 5, which is characterized in that the thickness of the base material It it is 6 μm~100 μm, the thickness of described adhesive layer is 1 μm~30 μm.