KR20180107732A - Surface protecting film - Google Patents

Abstract

The present invention provides an optical surface protecting film with low transmittance of ultraviolet rays, a suppressed color change, and excellent adhesion stability. The optical surface protecting film according to the present invention includes a substrate made of polyester-based resins, and an adhesive layer made of adhesive compositions on one side of the substrate. A b* value of the surface protecting film is 2 or less and the transmittance of the surface protecting film at a wavelength of 365nm is 2% or less. After the adhesive layer is attached to glass, a change rate of an adhesive force before heating and an adhesive force after heating at 100 degrees centigrade for 30 minutes is ± 30% or less.

Description

Surface Protective Film {SURFACE PROTECTING FILM}

The present invention relates to an optical surface protective film. Particularly, the surface of the optical member (for example, a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a reflection sheet, a brightness enhancement film, a cover glass for a display, etc. used for a liquid crystal display or the like) Is useful as a surface protective film for optical use which is used for protecting members,

The protective film generally has a constitution in which a pressure-sensitive adhesive layer is formed on a film-like base material. Such a protective film is bonded to an optical member which is an adhesive member via the above-mentioned pressure-sensitive adhesive layer, and is thereby used for the purpose of protecting the optical member from scratches and contamination of the surface during processing, transportation, inspection, and the like. For example, a panel of a liquid crystal display is formed by bonding an optical member such as a polarizing plate or a wave plate to a liquid crystal cell via a pressure sensitive adhesive layer (Patent Document 1).

As a protective film, it is required to be able to prevent the color change (discoloration such as rusting) of the protective film with time because the appearance inspection or the like may be performed in the state of being bonded to an optical member or the like.

Further, since the liquid crystal sealed in the liquid crystal cell used in the panel of the liquid crystal display is deteriorated by ultraviolet rays, a protective film having an ultraviolet absorbing function is bonded to a member such as a polarizing plate bonded to the liquid crystal cell.

In recent years, in manufacturing a cover glass for a mobile terminal such as a thin smartphone or a tablet, a bonding work is performed using a resin cured by active energy such as ultraviolet rays or heat. However, A member which is deteriorated by ultraviolet rays may be used. In order to protect such a member, a protective film containing an ultraviolet absorber is used.

The protective film used is peeled off at an unnecessary step. However, when a protective film attached to a cover glass used for a thin smart phone or the like is peeled off and removed, the protective film having an increased adhesive strength by ultraviolet rays, It may be difficult to peel off and peel off, resulting in breakage of the cover glass or the like.

Japanese Patent Application Laid-Open No. 2007-304425

Therefore, the present inventors have intensively studied in view of the above circumstances, and as a result, it is an object of the present invention to provide an optical surface protective film having low ultraviolet transmittance, suppressed color change, and excellent adhesion stability.

That is, the optical surface protective film of the present invention is an optical surface protective film comprising a base material formed of a polyester resin and a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition on one side of the base material, Is 2 or less and the transmittance of the surface protective film at a wavelength of 365 nm is 2% or less. After the pressure-sensitive adhesive layer is adhered to the glass, the adhesive strength before heating and the adhesive strength before heating at 100 占 폚 for 30 minutes And the rate of change of adhesive force is within ± 30%.

In the optical surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains an ultraviolet absorber.

In the optical surface protective film of the present invention, it is preferable that the number of hydroxyl groups in the molecule of the ultraviolet absorber is 3 or less.

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

In the optical surface protective 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 absorbent per 100 parts by weight of the base polymer.

In the optical surface protective film of the present invention, it is preferable that the thickness of the substrate is 6 to 100 占 퐉 and the thickness of the pressure-sensitive adhesive layer is 1 to 30 占 퐉.

Use of a surface protective film having a specific optical property is advantageous in that an optical surface protective film having a low transmittance of ultraviolet rays, suppressed color change, and excellent adhesion stability is obtained.

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

<Overall Structure of Optical Surface Protective Film>

The surface protective film for optical purposes (hereafter simply referred to as the "surface protective film") disclosed herein is a surface protective film which is generally referred to as an adhesive tape, an adhesive label, an adhesive film, And is a surface protective film for protecting the surface of an optical component during processing, inspection and transportation of optical components (for example, optical components used as components of a liquid crystal display panel of polarizing plates, wave plates, and cover glasses) Suitable. The pressure-sensitive adhesive layer in the above-mentioned surface protective film is typically formed continuously, but is not limited to this. For example, it may be a pressure-sensitive adhesive layer formed in a regular or random pattern such as a dot or stripe. The surface protective film disclosed herein may be in a roll form or in a leaf form.

<Description>

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

As the polyester-based resin, a polyester-based polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polybutylene terephthalate, And a resin material composed of a resin component (a main component in the resin component, typically 50 wt% or more) can be preferably used as the above-described base material. Examples of other resin materials other than the polyester-based resin include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer; Olefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Vinyl chloride polymers; Amide polymers such as nylon 6, nylon 6,6, and aromatic polyamides; And the like as a resin material. As another example of the resin material, there may be mentioned imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, Based polymer, an aryl-based polymer, a polyoxymethylene-based polymer, and an epoxy-based polymer. Or a substrate comprising two or more blends of the above-mentioned polymers.

The resin material constituting the substrate may be blended with various additives such as antioxidants, ultraviolet absorbers, plasticizers, colorants (pigments, dyes, etc.) if necessary. For example, a known or conventional surface treatment such as corona discharge treatment, plasma treatment, ultraviolet ray irradiation treatment, acid treatment, alkali treatment, application of a primer may be performed. Such a surface treatment may be, for example, a treatment for enhancing the adhesion (adhesion property of the pressure-sensitive adhesive layer) between the substrate and the pressure-sensitive adhesive layer.

As the substrate, it is also possible to use one having an antistatic treatment. Use of the above-described base material is preferable because the charging of the surface protective film itself when peeling off is suppressed. Further, by applying the antistatic treatment to the substrate, it is possible to obtain a surface electrification preventing film having a reduced electrification property and an excellent antistatic property to an adherend. The method for imparting the antistatic function is not particularly limited and conventionally known methods can be used. For example, an antistatic resin or a conductive polymer containing an antistatic agent and a resin component, a conductive polymer containing a conductive substance A method of applying a resin, a method of depositing or plating a conductive material, a method of knocking an antistatic agent, and the like.

The thickness of the base material is preferably 6 to 100 占 퐉, more preferably 10 to 60 占 퐉, and still more preferably 15 to 40 占 퐉. When the thickness of the base material is within the above range, bonding workability to an adherend, peelability from the adherend, and workability are excellent.

The surface protective film disclosed herein can be carried out in a form including another layer in addition to the base material and the pressure-sensitive adhesive layer. Examples of the other layer include an undercoating layer (anchor layer) for enhancing the transparency of the antistatic layer and the pressure-sensitive adhesive layer. Further, a separator may be attached for the purpose of protecting the surface of the pressure-sensitive adhesive layer.

<Pressure-sensitive adhesive layer>

The optical surface protective film of the present invention is characterized in that a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition is formed on one side of the base material. The pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as it is formed from a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive polymer having adhesiveness. Examples of the pressure sensitive adhesive composition include acrylic pressure sensitive adhesives, urethane pressure sensitive adhesives, synthetic rubber pressure sensitive adhesives, natural rubber pressure sensitive adhesives, silicone pressure sensitive adhesives and polyester pressure sensitive adhesives. Among them, the (meth) acrylic polymer and / It is preferable to use a pressure-sensitive adhesive composition containing a urethane-based polymer.

<Acrylic pressure-sensitive adhesive>

(Meth) acryl-based polymer having an alkyl group having 1 to 14 carbon atoms as the base polymer and a (meth) acrylic-based (meth) acrylic-based Monomers can be used as main monomers. As the (meth) acrylic monomers, one type or two or more types can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) with respect to the adherend (subject to be protected) to a low level, A protective film is obtained. The (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and (meth) acrylate refers to acrylate and / or methacrylate.

Specific examples of the (meth) acrylic monomers having an alkyl group of 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate, n-dodecyl (meth) acrylate, n-octyl (meth) acrylate, Tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate.

Among them, in the surface protective film of the present invention, it is particularly preferable to use a copolymer of n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate, n-decyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) (meth) acrylic monomers having an alkyl group having 4 to 14 carbon atoms such as n-decyl (meth) acrylate and n-tetradecyl (meth) acrylate. In particular, by using a (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) on the adherend to be low, and the re-peeling property is excellent.

In particular, it is preferable that the (meth) acrylic polymer contains 65% by weight or more of (meth) acrylic monomers having an alkyl group having 1 to 14 carbon atoms relative to 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer, By weight, more preferably 85 to 99.9% by weight, particularly preferably 90 to 99% by weight. When the content is less than 65% by weight, the appropriate wettability of the pressure-sensitive adhesive composition and the cohesive strength of the pressure-sensitive adhesive layer are deteriorated.

The (meth) acrylic polymer may be a (meth) acrylic monomer containing a hydroxyl group as a raw material monomer. The hydroxyl group-containing (meth) acrylic monomers may be used alone or in combination of two or more. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easy to control the crosslinking of the pressure-sensitive adhesive composition, and furthermore, the balance between the improvement of the wettability by the flow and the reduction of the peeling force It gets easier.

Examples of the hydroxyl group-containing (meth) acrylic monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) (Meth) acrylate, 2-hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl Hexyl) methyl acrylate, N-methylol (meth) acrylamide, and the like.

The content of the hydroxyl group-containing (meth) acryl-based monomer is preferably 25% by weight or less, more preferably 15% by weight or less, and even more preferably 15% by weight or less, relative to 100% by weight of the total amount of the monomer components constituting the (meth) Preferably 0.1 to 10% by weight, particularly preferably 1 to 5% by weight. Within this range, it is preferable to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the resulting pressure-sensitive adhesive layer.

As another polymerizable monomer component, it is preferable to adjust the glass transition temperature and the peelability of the (meth) acryl-based polymer so that the Tg is 0 DEG C or lower (usually -100 DEG C or higher) And the like can be used within a range that does not impair the effect of the present invention.

The (meth) acrylic polymer may be a (meth) acrylic monomer containing a carboxyl group as a raw material monomer. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress the increase of the adhesive strength with time in the pressure-sensitive adhesive layer (surface protective film), and it is excellent in re-peeling property, Further, it is preferable that the pressure-sensitive adhesive layer has excellent cohesive force and shear force.

Examples of the carboxyl group-containing (meth) acrylic monomers include (meth) acrylic acid, carboxylethyl (meth) acrylate, and carboxypentyl (meth) acrylate.

The content of the carboxyl group-containing (meth) acrylic monomer is preferably 10% by weight or less, more preferably 0 to 8% by weight, and more preferably 0 to 6% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) More preferably in weight%. Within this range, it is preferable to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the resulting pressure-sensitive adhesive layer.

The (meth) acryl-based polymer may be used without any particular limitation, provided that other polymerizable monomers other than the above-mentioned raw material monomers are within a range that does not impair the characteristics of the present invention. For example, as the other polymerizable monomer, a cohesive force / heat resistance improving component such as a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group- , Acryloylmorpholine, vinyl ether monomer, and the like, or a component having a functional group which acts as a crosslinking starting point can be suitably used. Among them, it is preferable to use a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and a nitrogen-containing monomer such as N-acryloylmorpholine. By using the nitrogen-containing monomer, a suitable peeling force (adhesive force) that does not cause floating or peeling can be secured, and a surface protective film excellent in shearing force can be obtained. These polymerizable monomers may be used alone 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, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropylmethacrylamide, diacetone acrylamide And the like.

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

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

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

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

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

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 amount of the monomer components constituting the (meth) acrylic polymer Do. The other polymerizable monomers can be suitably adjusted to obtain desired properties.

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

The average addition mole number of oxyalkylene units in the alkylene oxide group-containing reactive monomer is preferably 1 to 40, more preferably 3 to 40, from the viewpoint of compatibility with the oxyalkylene group-containing compound, More preferably from 4 to 35, and particularly preferably from 5 to 30. When the average added mole number is 1 or more, there is a tendency that the effect of reducing the stain on the adherend (subject to be protected) is efficiently obtained. When the above-mentioned average addition mole number is more than 40, the interaction with the oxyalkylene group-containing compound is so large that the viscosity of the pressure-sensitive adhesive composition tends to increase and the coating tends to become difficult. The terminal of the oxyalkylene chain may be substituted with a hydroxyl group or other functional group.

The alkylene oxide group-containing reactive monomer may be used singly or in admixture of two or more. The content of the alkylene oxide group-containing reactive monomer is preferably 0 to 20% by weight, based on the whole monomer component of the (meth) acrylic polymer , More preferably from 0 to 10% by weight. When the content of the alkylene oxide group-containing reactive monomer is more than 20% by weight, the staining property against the adherend is deteriorated, which is not preferable.

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

It is more preferable that the alkylene oxide group-containing reactive monomer is a reactive monomer having an ethylene oxide group. The use of the (meth) acryl-based polymer containing a reactive monomer having an ethylene oxide group as the base polymer improves the compatibility of the base polymer with the oxyalkylene group-containing compound and appropriately suppresses the bleeding to the adherend, A composition is obtained.

Examples of the alkylene oxide group-containing reactive monomer include alkylene oxide adducts of (meth) acrylic acid and reactive surfactants having reactive substituents such as acryloyl groups, methacryloyl groups and allyl groups in the molecule, and the like have.

Specific examples of the (meth) acrylate alkylene oxide adduct include polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol- (Meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate, (Meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, stearoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol Acrylate, octoxypolyethylene glycol-polypropylene glycol (Meth) acrylate, and the like.

Specific examples of the reactive surfactant include anionic type reactive surfactants having a (meth) acryloyl group or an allyl group, nonionic reactive surfactants, and cationic reactive surfactants.

The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, still more preferably 300,000 to 3,000,000, and most preferably 300,000 to 1,000,000. 1.2 million. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer is reduced, and the pressure-sensitive adhesive tends to remain. On the other hand, when the weight average molecular weight exceeds 500,000, the fluidity of the polymer is lowered, the wettability to an adherend (for example, a polarizing plate) becomes insufficient and the bubble generated between the adherend and the pressure- And the like. The weight average molecular weight refers to a value obtained by measurement by GPC (gel permeation chromatography).

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). When the glass transition temperature is higher than 0 占 폚, the polymer tends to flow hardly, for example, wetting of the polarizing plate as an optical member becomes insufficient, and tends to cause bubbles generated between the polarizing plate and the pressure-sensitive adhesive layer of the surface protective film . Particularly, when the glass transition temperature is lower than -70 캜, a pressure-sensitive adhesive layer having excellent wettability and light fastness to a polarizing plate tends to be obtained. The glass transition temperature of the (meth) acryl-based polymer can be adjusted within the above range by suitably changing the monomer components or the composition ratio to be used.

The polymerization method of the (meth) acrylic polymer is not particularly limited, and it can be polymerized by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. However, In view of properties such as low staining property against a protective body, solution polymerization is a more preferable form. The resulting polymer may be a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer or the like.

<Urethane type adhesive>

When a urethane-based pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, any appropriate urethane-based pressure-sensitive adhesive can be employed. As such urethane pressure-sensitive adhesives, those containing a urethane-based polymer, which is a pressure-sensitive adhesive polymer obtained by reacting a polyol with a polyisocyanate compound, may be used as the base polymer. As the urethane pressure-sensitive adhesive, those containing a polyurethane- The polyurethane resin refers to a resin obtained by curing a composition containing a polyol and a polyisocyanate compound.

The content of the polyurethane resin in the urethane pressure-sensitive adhesive is preferably not less than 40% by weight, more preferably not less than 50% by weight, more preferably not less than 55% by weight as a lower limit value, More preferably 99.999% by weight or less, still more preferably 99.9% by weight or less, still more preferably 99.9% by weight or less, still more preferably 60% by weight or less, By weight or less, more preferably 99% by weight or less, particularly preferably 95% by weight or less, and most preferably 90% by weight or less. The polyurethane resin may be one type or two or more types.

The polyol may be one kind or two or more kinds.

Any suitable polyol may be employed as the polyol, provided that it is a polyol having two or more OH groups. Examples of such a polyol include a polyol (diol) having two OH groups, a polyol (triol) having three OH groups, a polyol (tetraol) having four OH groups, a polyol (pentanol) having five OH groups, , A polyol having six OH groups (hexanol), and the like.

As the polyol, a polyol (triol) having preferably three OH groups can be employed. By employing a polyol (triol) having three OH groups as a polyol, for example, a pressure sensitive adhesive layer having a high wetting speed can be obtained. By combining with a specific substrate employed in the present invention, the detection rate of scratches or foreign matter incorporation A higher surface protective film can be provided. The content ratio of the polyol (triol) having three OH groups in the polyol is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, still more preferably 80 to 100% by weight, More preferably 90 to 100% by weight, particularly preferably 95 to 100% by weight, and most preferably substantially 100% by weight.

The polyol preferably includes a polyol having a number average molecular weight (Mn) of 400 to 20,000. The content 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, still more preferably 90 to 100% by weight , Particularly preferably 95 to 100 wt%, and most preferably substantially 100 wt%.

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 7000 to 20,000 and a triol having a number average molecular weight (Mn) of 2000 to 6000 Triols having a number average molecular weight (Mn) of 400 to 1900 are used in combination with a triol having a number average molecular weight (Mn) of 8000 to 15000 and a triol having a number average molecular weight (Mn) And a triol having a number average molecular weight (Mn) of 500 to 1800 are used in combination with triols having a number average molecular weight (Mn) of 8000 to 12000 and a triol having a number average molecular weight (Mn) Triols having 2,000 to 4,000 and triols having a number average molecular weight (Mn) of 500 to 1,500 are used in combination.

Examples of the polyol include a polyester polyol, a polyether polyol, a polycaprolactone polyol, a polycarbonate polyol, and a castor oil-based polyol.

The polyester polyol can be obtained, for example, by an esterification reaction of a polyol component and an acid component.

Examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, -Methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, polypropylene glycol and the like.

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, , 4-cyclohexane dicarboxylic acid, 2-ethyl-1,4-cyclohexane dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalene dicarboxylic acid, '-Biphenyldicarboxylic acid, and their acid anhydrides.

Examples of the polyether polyols include water, low molecular weight polyols such as propylene glycol, ethylene glycol, glycerin, trimethylol propane, pentaerythritol, etc., bisphenols such as bisphenol A, dihydroxybenzenes such as catechol, , Hydroquinone and the like) as an initiator and addition polymerization of an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide and the like. Specific examples thereof include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Examples of the polycaprolactone polyols include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as? -Caprolactone and? -Valerolactone.

Examples of the polycarbonate polyol include polycarbonate polyols obtained by polycondensation reaction of the polyol component and phosgene; The above-mentioned polyol component is mixed with the carbonic acid di (methane) carbonate such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, Polycarbonate polyols obtained by ester exchange condensation of esters; A copolymerized polycarbonate polyol obtained by using two or more of the above polyol components in combination; A polycarbonate polyol obtained by esterifying the various polycarbonate polyols and a carboxyl group-containing compound; A polycarbonate polyol obtained by etherifying the various polycarbonate polyols and a hydroxyl group-containing compound; A polycarbonate polyol obtained by transesterifying various polycarbonate polyols and an ester compound; A polycarbonate polyol obtained by an ester exchange reaction between the various polycarbonate polyols and a hydroxyl group-containing compound; A polyester polycarbonate polyol obtained by polycondensation reaction of the various polycarbonate polyols and a dicarboxylic acid compound; A copolymerized polyether polycarbonate polyol obtained by co-polymerizing the various polycarbonate polyols and an alkylene oxide; And the like.

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

The polyisocyanate compound (polyfunctional isocyanate compound) may be one kind or two or more kinds.

As the polyisocyanate compound (polyfunctional isocyanate compound), any appropriate polyisocyanate compound which can be used for the urethanization reaction can be employed. Examples of such a polyisocyanate compound include a polyfunctional aliphatic isocyanate compound, a polyfunctional alicyclic isocyanate, and a polyfunctional aromatic isocyanate compound.

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

Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di Isocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, and the like.

Examples of the polyfunctional aromatic diisocyanate compound include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-di Phenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, .

Examples of the polyisocyanate compound include trimethylolpropane adducts of various polyfunctional isocyanate compounds as described above, burettes obtained by reacting with water, and trimesters having isocyanurate rings. These may be used in combination.

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 the NCO group and the OH group in the polyol and the polyisocyanate compound is preferably 1.0 or more and 5.0 or less, more preferably 1.1 to 5.0, and still more preferably 1.2 or less, To 4.0, particularly preferably 1.5 to 3.5, and most preferably 1.8 to 3.0.

The polyurethane resin may include a fatty acid ester which can be used as a wettable additive. When the polyurethane resin contains a fatty acid ester, the wetting rate can be improved. The fatty acid ester may be one kind or two or more kinds.

The content of the fatty acid ester is preferably 5 to 50 parts by weight, more preferably 10 to 45 parts by weight, still more preferably 15 to 40 parts by weight, particularly preferably 100 to 5 parts by weight, 20 to 35 parts by weight, and most preferably 25 to 30 parts by weight. By adjusting the content of the fatty acid ester within the above range, the wetting rate can be further improved. If the content of the fatty acid ester is too small, there is a possibility that the wetting rate can not be sufficiently improved. If the content of the fatty acid ester is too large, there arises a problem that it is disadvantageous in terms of cost, a problem that the adhesive property can not be maintained, or a problem that the adherend is contaminated may occur.

The number average molecular weight (Mn) of the fatty acid ester is preferably 200 to 400, more preferably 210 to 395, still more preferably 230 to 380, particularly preferably 240 to 360, 270 to 340. By adjusting the number average molecular weight (Mn) of the fatty acid ester within the above range, the wetting rate can be further improved. If the number-average molecular weight (Mn) of the fatty acid ester is too small, there is a fear that the wetting rate will not be improved even when the amount is large. When the number average molecular weight (Mn) of the fatty acid ester is too large, the curing property of the pressure-sensitive adhesive at the time of drying deteriorates, and there is a possibility that adherence to the wetting property is adversely affected.

As the fatty acid ester, any suitable fatty acid ester can be employed as long as the effect of the present invention is not impaired. Examples of such fatty acid esters include polyoxyethylene bisphenol A lauric acid esters, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, behenic acid monoglyceride, 2-ethylhexanoate , Isopropyl myristate, isopropyl palmitate, cholesteryl isostearate, lauryl methacrylate, methyl coconut fatty acid, methyl laurate, methyl oleate, methyl stearate, myristyl myristate, myristic acid Pentaerythritol monostearate, pentaerythritol tetrapalmitate, stearyl stearate, isostearyl stearate, 2-ethylhexanoic acid triglyceride, butyl laurate, oleic acid Octyl and the like.

The polyurethane resin may include a leveling agent. By including the leveling agent in the polyurethane resin, appearance irregularity due to orange peel can be prevented. The leveling agent may be one type or two or more types.

As a method for obtaining a polyurethane resin by curing a composition containing the polyol and a polyisocyanate compound, any appropriate method may be used as long as the effect of the present invention is not impaired, such as a urethane formation reaction method using bulk polymerization or solution polymerization Can be adopted. However, in the conventional polyurethane-based resin obtained by passing through a so-called urethane prepolymer, there is a possibility that the effect of the present invention can not be exhibited. Therefore, a composition containing the polyol and a polyisocyanate compound is cured to obtain a polyurethane- The method is preferably a method other than the method of obtaining the polyurethane resin through the urethane prepolymer.

<Ultraviolet absorber>

In the optical surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition 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, it becomes possible to protect members which are liable to be deteriorated by ultraviolet rays. Further, by using an ultraviolet absorber having three or less hydroxyl groups, excellent adhesion stability of the pressure-sensitive adhesive layer is preferable. In addition, when the number of hydroxyl groups in the molecule of the ultraviolet absorber is large, it is presumed that the ultraviolet absorber reacts with the crosslinking agent, thereby hindering the curing of the pressure-sensitive adhesive composition.

Examples of the ultraviolet absorber include, but are not limited to, triazine-based ultraviolet absorbers, benzotriazole based ultraviolet absorbers, benzophenone based ultraviolet absorbers, oxybenzophenone based ultraviolet absorbers, salicylate ester based ultraviolet absorbers, cyanoacrylate based ultraviolet absorbers These may be used alone or in combination of two or more. Among them, the ultraviolet absorber preferably has three or less hydroxyl groups in the molecule.

Specific examples of the triazine-based ultraviolet absorber having 3 or less hydroxyl groups in one molecule include 2,4-bis [{4- (4-ethylhexyloxy) -4-hydroxy} - (4-methoxyphenyl) -1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis [2-hydroxy- (2,4-dimethylphenyl) -1,3,5-triazin-2-yl (dibutoxyphenyl) -1,3,5-triazine (TINUVIN 460, ) -5-hydroxyphenyl and [(C ₁₀ -C ₁₆ (predominantly C ₁₂ -C ₁₃₎ alkyloxy) methyl] oxirane reaction product of (TINUVIN400, BASF claim), 2- [4,6-bis (2 (4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- [3- (dodecyloxy) -2-hydroxypropoxy] phenol) (TINUVIN 405, produced by BASF), 2 (2-ethylhexyl) -glycidic acid ester, (4,6-diphenyl-1,3,5-triazin-2-yl) -5 - [(hexyl) oxy] -phenol (TINUVIN 1577, Triazin-2-yl) -5- [2- (2-ethylhexano Oxy) ethoxy] -phenol (ADK STAB LA46, manufactured by ADEKA), 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] -1,3,5-triazine (TINUVIN479, manufactured by BASF), and the like.

Examples of the benzotriazole ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) Phenol (TINUVIN 928 from BASF), 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (from TINUVIN PS, BASF), benzenepropanoic acid and 3- 2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C ₇ - ₉ and the side chain ester (TINUVIN384-2, BASF claim), 2- (2H- benzo straight chain alkyl) triazole (1-methyl-1-phenylethyl) phenol (TINUVIN900, produced by BASF), 2- (2H-benzotriazol- (1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol (TINUVIN 928, manufactured by BASF) (TINUVIN 1130, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -p-cresol (TINUVIN P, BASF Bis (1-methyl-1-phenylethyl) phenol (TINUVIN234, manufactured by BASF), 2- [5- (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol (TINUVIN 326 from BASF), (TINUVIN 326 FL from BASF) (2-yl) -4,6-di-tert-pentylphenol (TINUVIN 328, manufactured by BASF), 2- (2H-benzotriazol- ) Phenol (TINUVIN 329, manufactured by BASF), the reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert- butyl-4-hydroxyphenyl) propionate with polyethylene glycol 300 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (TINUVIN571, manufactured by BASF) , 5,6-tetrahydrophthalimidemethyl) -5-methylphenyl] benzotriazole (Sumisorb 250, available from Sumitomo Chemical Co., Ltd.).

Examples of the benzophenone ultraviolet absorber (benzophenone compound) and oxybenzophenone ultraviolet absorber (oxybenzophenone compound) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy Benzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydride and trichostearate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy- Benzyloxy-2-hydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, 2,2' -Dihydroxy-4-methoxybenzophenone (KEMISORB 111, Chemipro Gaseous), and the like.

Examples of the salicylic acid ester-based ultraviolet absorber (salicylic ester compound) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, Acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, 2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy- Tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN 120, manufactured by BASF).

Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, Alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The ultraviolet absorber may be used singly or in admixture of two or more. The content of the ultraviolet absorber as a whole is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the base polymer, 0.5 To 15 parts by weight, more preferably 1 to 10 parts by weight. When the content of the ultraviolet absorber is within the above range, the ultraviolet ray absorbing function of the pressure-sensitive adhesive layer can be sufficiently exhibited, and it is preferable that the ultraviolet ray absorbing agent does not interfere with ultraviolet ray polymerization.

<Antioxidant>

In the optical surface protective film of the present invention, the pressure-sensitive adhesive composition may contain an antioxidant, and examples thereof include a radical chain inhibitor and a peroxide decomposition product.

Examples of the radical chain inhibitor include phenol-based antioxidants and amine-based antioxidants.

Examples of the release of the peroxide may include a sulfur-based antioxidant and a phosphorus-based antioxidant.

Examples of the phenol-based antioxidant include monophenol-based antioxidants, bisphenol-based antioxidants, and polymer-based phenol-based antioxidants.

Examples of the monophenol antioxidant include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di- - (3,5-di-t-butyl-4-hydroxyphenyl) propionate.

Examples of the bisphenol-based antioxidant include 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl- Dimethyl-2- [? - (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane .

Examples of the polymer type phenolic antioxidant include 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5- (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- Propionate] methane, bis [3,3'-bis- (4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, 1,3,5- (1H, 3H, 5H) trione, tocopherol, pentaerythritol tetrakis [3- (3 ', 5'- 5'-di-tert-butyl-4'-hydroxyphenyl) propionate].

Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, etc. .

Examples of the phosphorus antioxidant include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite and the like.

The antioxidant may be used singly or in admixture of two or more. The content of the antioxidant as a whole is preferably 0.01 to 1 part by weight, more preferably 0.1 to 1 part by weight per 100 parts by weight of the base polymer, To 0.8 parts by weight, more preferably 0.2 to 0.7 parts by weight. When the content of the antioxidant is within the above range, deterioration due to oxidation of the pressure-sensitive adhesive layer can be sufficiently inhibited, and the pressure-sensitive adhesive property is stable.

&Lt; Oxyalkylene group-containing compound >

The pressure-sensitive adhesive composition used in the present invention may contain an oxyalkylene group-containing compound. By containing the oxyalkylene group-containing compound, it is also possible to express the light yellow solubility. Examples of the oxyalkylene group-containing compound include an oxyalkylene group-containing compound not containing an organopolysiloxane having an oxyalkylene chain or an organopolysiloxane.

<Cross-linking agent>

In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a crosslinking agent. Further, in the present invention, the pressure-sensitive adhesive composition may be used to form a pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acryl-based polymer, by appropriately controlling and crosslinking the constituent unit, the constituent ratio, the selection and the addition ratio of the (meth) acrylic polymer, A pressure-sensitive adhesive layer (surface protective film) excellent in heat resistance can be obtained. Further, in the case of the urethane-based pressure-sensitive adhesive containing the urethane-based polymer, crosslinking by appropriately controlling the constitutional unit, the constituent ratio, the selection of the crosslinking agent, the ratio of the additive and the like of the polyol makes it possible to obtain excellent initial reworkability, An excellent pressure-sensitive adhesive layer (surface protective film) can be obtained.

As the crosslinking agent to be used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative and a metal chelate compound may be used, and in particular, the use of an isocyanate compound or an epoxy compound is a preferable form. 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, butylenediisocyanate, hexamethylene diisocyanate (HDI) and dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI) and 1,3-bis (isocyanatomethyl) cyclohexane; alicyclic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI) , An aromatic isocyanate compound such as an isocyanate compound represented by the following general formula (1), an isocyanate compound represented by the following general formula (1), an isocyanate compound such as an isocyanate compound, an isocyanate compound, a urea bond, a urea bond, a carbodiimide bond, And a polyisocyanate-modified product. For example, as commercial products, there may be mentioned trade names of Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (manufactured by Mitsui Chemicals), Sumidur T80, Sumidur L, , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by TOSOH CORPORATION), and the like. These isocyanate compounds may be used alone, or two or more isocyanate compounds may be used in combination, or a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. A pressure-sensitive adhesive layer (surface protective film) which is more excellent in adhesion reliability can be obtained by using both the pressure-sensitive adhesive layer and the crosslinking agent in combination.

Examples of the epoxy compound include N, N, N ', N'-tetraglycidyl-m-xylenediamine (trade name TETRAD-X manufactured by Mitsubishi Gas Chemical Company) Diglycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company).

Examples of the melamine resin include hexamethylol melamine and the like. Examples of the aziridine derivative include HDU, TAZM and TAZO (trade name, manufactured by Sogo Kogyo Kogyo Co., Ltd.) as a commercial product.

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

The content of the crosslinking agent used in the present invention is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer And most preferably 1 to 8 parts by weight. When the content is less than 0.01 part by weight, crosslinking by the crosslinking agent becomes insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer becomes small, sufficient heat resistance may not be obtained, and the pressure-sensitive adhesive tends to remain. On the other hand, when the content is more than 20 parts by weight, the cohesive force of the polymer is large and the fluidity is lowered, and the wettability to an adherend (for example, a polarizing plate) becomes insufficient and the adhesion between the adherend and the pressure- It tends to cause bubbles to be generated. These crosslinking agents may be used alone or in combination of two or more. In the case of the urethane-based pressure sensitive adhesive containing the urethane polymer, the content of the crosslinking agent is preferably 5 to 30 parts by weight, more preferably 5 to 28 parts by weight, more preferably 5 to 30 parts by weight, Is 5 to 25 parts by weight, particularly preferably 5 to 23 parts by weight. By adjusting the content of the cross-linking agent within the above range, the resulting pressure-sensitive adhesive layer has excellent initial tackiness when bonded to an adherend and excellent adhesion reliability after aging.

&Lt; Crosslinking catalyst &

The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for further promoting any of the crosslinking reactions described above. Examples of such a crosslinking catalyst include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate (dioctyltin dilaurate), tris (acetylacetonate) iron, tris (hexane-2,4- Tris (heptane-2,4-dianato) iron, tris (heptane-3,5-dianato) iron, tris (5-methylhexane- (2,4-dianato) iron, tris (6-methylheptane-2,4-dianato) iron, tris (2,6-dimethylheptane- Iron, tris (nonane-4,6-dianato) iron, tris (2,2,6,6-tetramethylheptane-3,5-dianato) iron, tris (tridecane-6,8 Iron, tris (ethyl acetoacetate) iron, tris (acetoacetic acid-n-propyl) iron, tris (acetoacetic acid-n-propyl) Iron, tris (isopropyl acetoacetate), tris (acetoacetic acid-n-butyl) iron, Tris (acetoacetic acid-sec-butyl) iron, tris (acetoacetic acid-tert-butyl) iron, tris (propionylacetic acid methyl) Iron, tris (propionylacetic acid isopropyl) iron, tris (propionylacetate-n-butyl) iron, tris (propionylacetic acid-sec-butyl) Based catalysts such as benzoyl acetylacetonate, iron tris (dimethyl malonate), tris (diethyl malonate), trimethoxy iron, triethoxy iron, triisopropoxy iron and ferric chloride can be used . These crosslinking catalysts may be used alone or in combination of two or more.

The content of the crosslinking catalyst is not particularly limited, but is preferably about 0.0001 to 1 part by weight, more preferably 0.001 to 0.5 part by weight, per 100 parts by weight of the (meth) acrylic polymer. Within the above range, the speed of the crosslinking reaction is high when the pressure-sensitive adhesive layer is formed, and the time for which the pressure-sensitive adhesive composition is used becomes long, which is a preferable form. In addition, they may be of only one kind, or two or more kinds. In the case of the urethane-based pressure sensitive adhesive containing the urethane polymer, the content of the crosslinking catalyst is preferably 0.01 to 1 part by weight, more preferably 0.08 to 0.5 part by weight, based on 100 parts by weight of the polyol.

<Other additives>

In addition, the pressure-sensitive adhesive composition may contain other known additives within the range not impairing the effects of the present invention. For example, the pressure-sensitive adhesive composition may contain a powder such as a lubricant, a colorant, a pigment, a solvent, a plasticizer, , A low molecular weight polymer, a surface lubricant, a leveling agent, a wetting additive, an antioxidant, a corrosion inhibitor, a light stabilizer, a heat stabilizer, an ultraviolet absorbent, a polymerization inhibitor, a silane coupling agent, an antistatic agent, And may be suitably added in accordance with the use of a foaming agent or the like.

&Lt; Surface protective film for optical use &

The optical surface protective film (surface protective film) of the present invention comprises a base material comprising a polyester resin and a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition on one side of the base material. It is generally carried out after application of the pressure-sensitive adhesive composition. However, it is also possible to transfer the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition after crosslinking to a substrate or the like.

A method of forming a pressure-sensitive adhesive layer on a substrate is not particularly limited, and is produced, for example, by applying the pressure-sensitive adhesive composition (solution) to a substrate, and drying the polymerization solvent or the like to dry to form a pressure-sensitive adhesive layer on the substrate. Thereafter, curing may be performed for the purpose of adjusting the component migration of the pressure-sensitive adhesive layer and adjusting the crosslinking reaction. When the pressure-sensitive adhesive composition is applied onto a substrate to produce a surface protective film, at least one solvent other than the polymerization solvent may be newly added to the pressure-sensitive adhesive composition so as to be uniformly applied on the substrate.

As a method of forming the pressure-sensitive adhesive layer in the production of the surface protective film of the present invention, a known method used for production of pressure-sensitive adhesive tapes is used. Specifically, for example, there may be mentioned an extrusion coating method using a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method or a die coater.

The thickness of the pressure-sensitive adhesive layer is preferably 1 to 30 占 퐉, more preferably 2 to 28 占 퐉, and still more preferably 3 to 25 占 퐉. When the thickness of the pressure-sensitive adhesive layer is within the above-mentioned range, it is preferable that a proper balance of re-peeling property and tackiness can be easily obtained.

The total thickness of the surface protective film of the present invention is preferably 7 to 130 占 퐉, more preferably 10 to 100 占 퐉, and still more preferably 20 to 50 占 퐉. Within the above-mentioned range, the composition is excellent in adhesive properties (re-peelability, tackiness, adhesion stability, etc.), workability, and appearance. The total thickness means the sum of thicknesses including all layers such as a substrate, a pressure-sensitive adhesive layer, a separator, and other layers.

<Separator>

In the surface protective film of the present invention, if necessary, it is possible to bond the separator for the purpose of protecting the surface of the pressure-sensitive adhesive layer.

As a material constituting the separator, there are a paper or a plastic film, but a plastic film is suitably used because of its excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, A polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually 5 to 200 占 퐉, preferably 8 to 100 占 퐉, and more preferably 10 to 50 占 퐉. If necessary, the separator may also be subjected to antistatic treatment such as releasing treatment with a silicone, fluorine, long chain alkyl or fatty acid amide releasing agent, silica powder or the like, a coating type, a kneading type, a deposition type or the like.

The surface protective film disclosed herein may be applied in addition to the support and the pressure-sensitive adhesive layer, and also in the form including another layer. Examples of the other layer include an undercoating layer (anchor layer) for enhancing the transparency of the antistatic layer and the pressure-sensitive adhesive layer.

&Lt; Method of using surface protective film for optical &

As a method of using the optical surface protective film of the present invention, for example, there is a method of bonding the surface of the pressure sensitive adhesive layer constituting the optical surface protective film of the present invention to the surface of a part of the printed portion of the printing glass, The surface protective film for optical is not bonded and the ultraviolet curable resin is applied to the exposed portion and the deterioration of the portion not coated with the ultraviolet curable resin to which the optical surface protective film is attached is prevented from being deteriorated by ultraviolet rays. According to this use method, it is possible to protect the members such as the progress of the curing reaction by irradiation of ultraviolet rays, the printing portion which is desired to prevent deterioration by ultraviolet ray irradiation, and the like.

&Lt; Optical member &

In the present invention, the surface of the pressure-sensitive adhesive layer of the optical surface protective film may be attached to the optical member to protect the optical member. The above surface protective film can prevent an increase in adhesive force even after being adhered to an optical member or the like serving as an adhesive for a pressure-sensitive adhesive layer and heated, and is excellent in adhesive strength stability and excellent in releasability, It can be used for surface protection use (surface protective film) at the time of shipment and the like, so that it is useful for protecting the surface of the optical member (polarizing plate or the like). Further, since the color change of the pressure-sensitive adhesive layer constituting the surface protective film is suppressed and the transmittance of ultraviolet rays is suppressed to a low level throughout the surface protective film, inspection can be carried out in the state that the surface protective film is bonded to the optical member, It is a preferred form because it can be used for the purpose of suppressing hardening or deterioration accompanying irradiation.

[Example]

Hereinafter, some embodiments related to the present invention will be described, but the present invention is not intended to be limited to what is shown in these embodiments. In the following description, &quot; part &quot; and &quot;% &quot; are by weight unless otherwise specified. In addition, the blending amount (added amount) in the table is shown.

Each characteristic in the following description was measured or evaluated as follows.

<Measurement of Glass Transition Temperature (Tg) of Acrylic Polymer>

The glass transition temperature (Tg) (占 폚) was a glass transition temperature Tgn (占 폚) of the homopolymer by each monomer, and was determined by the following formula using the following literatures.

1 / (Tg + 273) =? [Wn / (Tgn + 273)

Wherein Tg (° C) is the glass transition temperature of the copolymer, Wn (-) is the weight fraction of each monomer, Tgn (° C) is the glass transition temperature of the homopolymer by each monomer, and n is the kind of each monomer )

Literature value:

2-ethylhexyl acrylate (2EHA): -70 占 폚

2-hydroxyethyl acrylate (HEA): -15 ° C

In addition, reference was made to "Synthesis, design and development of new applications of acrylic resin" (published by Central Management Development Center Press) as a literature value.

&Lt; 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 a GPC (HLC-8220GPC) manufactured by TOSOH CORPORATION. The measurement conditions are as follows.

Sample concentration: 0.2 wt% (THF solution)

Sample injection amount: 10 μl

Eluent: THF

Flow rate: 0.6 ml / min

Measuring temperature: 40 ° C

column :

Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)

Reference column; TSKgel SuperH-RC (1)

Detector: Differential refractometer (RI)

In addition, the weight average molecular weight was determined in terms of polystyrene conversion. In addition, not only the acrylic polymer but also the number average molecular weight (Mn) was measured in the same manner as the weight average molecular weight (Mw).

< Measurement of b * value >

The optical surface protective film (surface protective film) for each example was aged at room temperature for 7 days, cut into a size of 50 mm in width and 50 mm in length, peeled from the surface of the pressure sensitive adhesive layer of the surface protective film, The &quot; b * value &quot; was measured by a high-speed integral-transmittance transmittance meter (manufactured by Murakami Shikisai Co., Ltd., type "DOT-3C"). Also, the b * value indicates the CIELab value.

The b * value of the surface protective film is 2 or less, preferably 1.6 or less, and more preferably 1.2 or less. When the b * value is within the above range, the color change of the pressure-sensitive adhesive layer is suppressed, and inspection can be carried out even when attached to the optical member.

<Measurement of transmittance>

The transmittance was measured by using a spectrophotometer U-4100 manufactured by Hitachi, Ltd. The light having a wavelength of 300 to 400 nm was vertically incident on the surface of the substrate from the substrate side of the optical surface protective film obtained according to Examples and Comparative Examples, (%). The transmittance (ultraviolet transmittance) shows the transmittance (%) at a wavelength of 365 nm in the transmittance to the light in the above range.

The transmittance is 2% or less, preferably 1.8% or less, and more preferably 1.6% or less. If the transmittance exceeds 2%, the transmittance of ultraviolet rays is high, so that curing or deterioration due to ultraviolet irradiation can not be prevented. For example, the strength of the printed portion is lowered.

&Lt; Initial Adhesion (Adhesion before Heating) >

The surface protective film of each example was cut to a width of 25 mm and the side of the pressure sensitive adhesive surface of the optical surface protective film from which the separator was peeled was placed on the surface of a glass plate (trade name: Micro Slide Glass S, manufactured by Matsunami Glass Co., The sheet was allowed to stand at room temperature (23 DEG C, 50% RH) for 20 minutes and then subjected to a tensile compression test using a tensile compression tester (TG-1kN, manufactured by Minebea) And peeled off under the conditions of a peeling speed of 0.3 m / min and peeling force (large glass adhesion) of the surface protective film was measured as &quot; initial adhesive force (adhesive force before heating) &quot; (N / 25 mm).

Measurement conditions: Temperature: 23 ± 2 ° C, Humidity: 50 ± 5% RH

&Lt; Adhesion after heating >

After the test piece was prepared, the test piece was heated at 100 占 폚 for 30 minutes and then allowed to stand at room temperature (23 占 폚, 50% RH) for 1 hour. Then, under the same conditions as the initial tackiness, N / 25 mm) was measured.

The above-mentioned large glass adhesion is preferably 0.2 N / 25 mm or less, more preferably 0.15 N / 25 mm or less, and even more preferably 0.1 N / / 25 mm or less. When the adhesive force is more than 0.2 N / 25 mm, the adhesive force becomes too high, and the light fastness (re-releasability) becomes difficult. For example, when used as a surface protective film, Or the base material may be damaged, which is not preferable.

&Lt; Rate of change of adhesive force before and after heating >

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

(% Change in adhesive force before and after heating) = 100 占 (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, and more preferably ± 20% or less. When the rate of change exceeds 賊 30%, it causes a problem of heavy peeling or peeling, which is not preferable.

[Example 1]

[Production of acrylic polymer]

200 parts by weight of 2-ethylhexyl acrylate (2EHA), 8 parts by weight of 2-hydroxyethyl acrylate (HEA), and 2 parts by weight of 2-ethylhexyl acrylate as a polymerization initiator were added to a four-necked flask equipped with a stirrer, a thermometer, , 0.4 parts by weight of 2'-azobisisobutyronitrile and 312 parts by weight of ethyl acetate as a solvent were fed into a flask, and nitrogen gas was introduced with gentle stirring. The liquid temperature in the flask was maintained at about 65 DEG C for 6 hours, , And an acrylic polymer solution (40% by weight). The acrylic polymer had a weight average molecular weight (Mw) of 540,000 and a glass transition temperature (Tg) of -68 ° C.

[Preparation of acrylic pressure-sensitive adhesive solution]

The acrylic polymer solution (40% by weight) was diluted to 29% by weight with ethyl acetate, and an isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name, 4 parts by weight of Coronate HX in Table 1), 4 parts by weight of dibutyl tin dilaurate (manufactured by TOKYO PINE CHEMICAL INDUSTRIES, trade name: Envisizer OL-1, &quot; OL- (4-ethylhexyloxy) -4-hydroxy} -phenyl] -6- (4-methoxyphenol) as an ultraviolet absorber Phenyl) -1,3,5-triazine (trade name: Tinosorb S, manufactured by BASF) as a crosslinking retarder and 3 parts by weight of acetylacetone as a crosslinking retarder in an amount of 3 parts by weight based on the total amount of the solvent were mixed and stirred to prepare an acrylic pressure- (Pressure-sensitive adhesive composition).

[Production of optical surface protective film]

The acrylic pressure-sensitive adhesive solution was coated on a surface opposite to the antistatic-treated surface of a polyethylene terephthalate film (trade name: Diofoil T100G38, made by Mitsubishi Gas Chemical Co., Ltd., thickness 38 μm) having an antistatic treatment layer as a substrate, For 1 minute to form a pressure-sensitive adhesive layer having a thickness of 21 mu m. Subsequently, a silicone-treated surface of a separator (a polyethylene terephthalate film having a thickness of 21 占 퐉 and subjected to a silicon treatment on one side) was bonded to the surface of the pressure-sensitive adhesive layer to prepare an optical surface protective film.

&Lt; Examples 2 to 5 and Comparative Examples 1 to 3 >

An optical surface protective film was prepared in the same manner as in Example 1, based on the formulation shown in Table 1.

&Lt; Examples 6 and 7 >

A polyester film having a thickness of 12 占 퐉 (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Diofoil T100G12) was used in place of the substrate used in Example 1, and on the basis of the content shown in Table 1, To prepare an optical surface protective film.

&Lt; Examples 8 and 9 >

A polyester film (trade name: SRF, manufactured by Toyobo Co., Ltd.) having a thickness of 80 占 퐉 was used in place of the substrate used in Example 1, and on the basis of the content shown in Table 1, A surface protective film was prepared.

&Lt; Example 10 >

[Preparation of urethane pressure-sensitive adhesive solution]

85 parts by weight of Prinin S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000), 13 parts by weight of Sanix GP3000 (manufactured by Sanyo Chemical Industries, Ltd., Mn = 3000), 13 parts by weight of SANNIX GP1000 , 10 parts by weight of Tinuvin 384-2 (manufactured by BSF) as an ultraviolet absorber, 18 parts by weight of a polyfunctional alicyclic isocyanate compound (tradename: Coronate HX) as a crosslinking agent, 0.08 part by weight of a crosslinking catalyst (manufactured by Nihon Kagaku Kogyo K.K., trade name: Nasematic Ferric), 0.5 part by weight of Irganox 1010 (manufactured by BASF) as an antioxidant, (Trade name: EXSEPAR IPM) (30 parts by weight), and ethyl acetate as a diluting solvent (210 parts by weight) were mixed and stirred with a disper to obtain a urethane pressure-sensitive adhesive solution (pressure-sensitive adhesive composition).

[Production of optical surface protective film]

The urethane pressure-sensitive adhesive composition was coated on a surface opposite to the antistatic-treated surface of a polyethylene terephthalate film (trade name: Diaphoto T100G38, manufactured by Mitsubishi Gas Chemical Co., Ltd., thickness 38 탆) having an antistatic treatment layer as a substrate, For 1 minute to form a pressure-sensitive adhesive layer having a thickness of 20 m. Subsequently, a silicone surface of a separator (a polyethylene terephthalate film having a thickness of 25 占 퐉 and subjected to a silicon treatment on one side) was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protective film for optical use.

Table 1 and Table 2 show the results of the above formulation, various measurements and evaluations of the optical surface protective film provided with the separator according to Examples and Comparative Examples. The compounding amounts in Table 1 indicate the active ingredients.

Details of abbreviations in Table 1 are shown below.

<Description>

Diafoil T100G38: Thickness 38 mu m, manufactured by Mitsubishi Rayon Co., Ltd. Product name: Diafoil T100G38

Diafoil T100G12: thickness 12 占 퐉, manufactured by Mitsubishi Chemical Corporation, trade name: Diafoil T100G12

SRF: thickness 80 占 퐉, product name: SRF

<Ultraviolet absorber>

Tinosorb S: 2,4-Bis- [{4- (4-ethylhexyloxy) -4-hydroxy} -phenyl] -6- (4- methoxyphenyl) Trade name: Tinosorb S, manufactured by BASF, hydroxyl number: 2)

Tinuvin 571: 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, trade name: Tinuvin 571,

Tinuvin 384-2: benzene propanoic acid and 3- (2H- benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C ₇ - ₉ branched and straight-chain alkyl) ester of Compound, product of BASF, trade name: Tinuvin 384-2, hydroxyl number: 1)

Tinuvin 326: 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert- butyl) phenol, trade name: TINUVIN326,

KEMISORB 111: 2,2'-dihydroxy-4-methoxybenzophenone, trade name: KEMISORB 111, hydroxyl number: 2)

SEESORB 106: 2-hydroxy-4-methoxybenzophenone, manufactured by Cipro Gage AG, trade name: SEESORB 106, hydroxyl number: 4)

<Antioxidant>

Irganox 1010: pentaerythritol tetrakis [3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], trade name: Irganox 1010

&Lt; Wettability additive &

Myristic acid isopropyl, Gao Ze, trade name: EXSEPAR IPM

From Table 2, it was confirmed that the color change was suppressed in all the examples, the ultraviolet curing could be prevented, and the adhesion strength after heating could be prevented. On the other hand, in Comparative Example 1, the ultraviolet transmittance was slightly high, and the prevention of deterioration upon irradiation with ultraviolet rays was insufficient. In Comparative Example 2, since the number of hydroxyl groups of the ultraviolet absorber used was large, the rate of change of the adhesive force before and after heating was large, and it became heavy and was unsuitable for use in light leathers. In Comparative Example 3, It was confirmed that the use of a material (member) to prevent ultraviolet curing (absorption) was inadequate because of a very high ultraviolet transmittance.

The optical surface protective film disclosed herein can be used for manufacturing optical members used as components of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display and the like, As a surface protective film for protecting the film. Particularly, a surface protective film for optical applications, which is applied to optical members such as a polarizing plate for a liquid crystal display panel, a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light diffusion sheet, .

Claims (6)

1. A surface protective film for optical use comprising a substrate formed of a polyester resin and a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition on one side of the substrate,
Wherein the surface protective film has a b * value of not more than 2, and the surface protective film has a transmittance of not more than 2% at a wavelength of 365 nm, And the rate of change of the adhesive force after heating for 30 minutes is not more than 30%. The method according to claim 1,
Wherein the pressure-sensitive adhesive composition contains an ultraviolet absorber. 3. The method of claim 2,
Wherein the ultraviolet absorber has 3 or less hydroxyl groups in the molecule thereof. 4. The method according to any one of claims 1 to 3,
Wherein the pressure-sensitive adhesive composition contains a (meth) acryl-based polymer and / or a urethane-based polymer as a base polymer. 5. The method of claim 4,
Wherein the pressure-sensitive adhesive composition contains 0.1 to 20 parts by weight of the ultraviolet absorbing agent per 100 parts by weight of the base polymer. 6. The method according to any one of claims 1 to 5,
Wherein the thickness of the substrate is 6 to 100 占 퐉 and the thickness of the pressure-sensitive adhesive layer is 1 to 30 占 퐉.