KR20220121031A - Polarizer plate comprising protection film and method for peeling the protection film - Google Patents

Abstract

The present invention relates to a polarizing plate having a structure, where a first protection film, a polarizer, and a second protection film are sequentially laminated, and a protection film separation method from the same. According to the present invention, when using the polarizing plate having the protection film and the protection film separation method thereof, the protection film is not bulged from the polarizing plate to have excellent storage stability even when the protection film is stored for a long period of time, there is no problem such as residue or a stain of an adhesive after separation, and effectively separates only the protection film on one preferred surface among the double-sided protection film without double-sided separation.

Description

Polarizing plate including a protective film and peeling method of the protective film

The present invention relates to a polarizing plate including a protective film and a method for peeling the protective film.

The polarizing plate is an optically functional film applied to an image display device such as a liquid crystal display (LCD) or an organic light emitting diode display (OLED).

In general, a polarizing plate is very sensitive to heat and moisture, and thus, a polyvinyl alcohol (PVA) polarizer containing an iodine-based compound or a dichroic polarizing material and a protective layer such as triacetate cellulose (TAC) to protect the polarizer It was prepared including a protective film that serves as the

However, as a result, the overall thickness and manufacturing cost of the polarizing plate including the protective layer increased, and as a thin polarizing plate was required, recently, instead of the role of a protective film, it was directly combined with a retardation film or liquid crystal cell of an image display device. , efforts to lower the overall thickness of the display including the polarizer are continuing.

Therefore, the protective film is used for temporary bonding to protect the polarizer until it is directly bonded to the retardation film or the image display device, and the protective film is peeled and removed before performing the product manufacturing process for the polarizer.

Therefore, in the case of a protective film, it is necessary to prevent the problem that the protective film is lifted during the storage or transport process of the polarizing plate, and during the peeling operation of peeling the protective film on one side from the polarizing plate among the protective films on both sides, the protective film is not peeled cleanly or the peeling target is not Instead, there should be no problem of peeling together with the back protective film, and properties capable of suppressing problems such as the generation of residues of adhesives on the polarizing plate or the panel and the occurrence of stains are required.

Conventionally, as a method of peeling a protective film from a polarizing plate, a technique using a contact peeling tool or a mechanical device has been proposed. Therefore, there was a problem in that the entire peeling process becomes complicated. In addition, there is a disadvantage that the peeling tool is in contact with the surface of the polarizing plate or the like, causing surface damage.

Korean Patent No. 10-1818473, etc. discloses a peeling device for peeling a protective film from a polarizing plate, but includes a complicated driving device for peeling, so the process is complicated, the equipment arrangement area is large, and maintenance of the device is difficult. The downside is that it's not easy.

Republic of Korea Patent Registration No. 10-1818473 (2018.01.16. Announcement)

The present invention is a polarizing plate comprising a protective film that has excellent storage stability, does not cause problems such as adhesive residue or stains after peeling, and can effectively peel only a protective film on one side of the protective film on both sides, and a protective film therefor It is an object of the present invention to provide a peeling method of

In order to achieve the above object,

The present invention is a polarizing plate including a structure in which a first protective film, a polarizer and a second protective film are laminated in order, and includes a second adhesive for attaching the second protective film and the polarizer, wherein the second adhesive is variable It provides a polarizing plate comprising a protective film, characterized in that the adhesive.

In addition, the present invention provides a method of peeling a protective film from a polarizing plate including a structure in which a first protective film, a polarizer, and a second protective film are sequentially stacked, the method comprising the steps of: 1) surface-modifying the polarizer; 2) bonding the polarizer to the first protective film and the second protective film using a first adhesive and a second adhesive, respectively; and 3) peeling the second protective film from the polarizer by irradiating ultraviolet (UV) light on the second protective film.

In the case of using the polarizing plate comprising the protective film according to the present invention and the peeling method of the protective film, the protective film does not float on the polarizing plate even when stored for a long period of time, so storage stability is excellent, and problems such as adhesive residue or stains after peeling occur It can provide an effect of effectively peeling only a desired protective film on one side without a double-sided peeling problem among the protective films on both sides.

The present invention relates to a polarizing plate including a protective film and a method for peeling the protective film.

Hereinafter, the present invention will be described in detail.

Throughout this specification, when a member is referred to as being “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

In the present specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

<Polarizer>

A polarizing plate including a protective film according to the present invention includes a structure in which a first protective film, a polarizer, and a second protective film are laminated in order, wherein the polarizer and the first protective film or the second protective film are combined with an adhesive composition it could be

polarizer

The polarizer according to the present invention is an optical film that serves to change incident natural light into a desired single polarization state (linear polarization state), and includes steps such as swelling, dyeing, crosslinking, stretching, washing with water, drying, etc. It may be a polarizer commonly used in the art manufactured according to the process.

As the polarizer, the type is not particularly limited as long as it is a dichroic material, that is, a film that can be dyed with iodine. a film, a polyethylene terephthalate film, an ethylene-vinyl acetate copolymer film, an ethylene-vinyl alcohol copolymer film, a cellulose film, these partially saponified films, etc. are mentioned. Among them, a polyvinyl alcohol-based film is preferable in that it is excellent in the effect of enhancing the uniformity of the degree of polarization in the plane and also has excellent dyeing affinity to iodine.

The polyvinyl alcohol-based resin constituting the polarizer can be produced by saponifying polyvinyl acetate-based resin. The degree of saponification of the polyvinyl alcohol-based resin may be 85 to 100 mol%, preferably 90 mol% or more, and more preferably 98 to 100 mol%.

Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other copolymerizable monomers. Specific examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, unsaturated amines, vinyl ethers, and acrylamides having an ammonium group.

In addition, the polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal, polyvinyl acetal or polyvinyl butyral modified with aldehydes may be used.

The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

The polyvinyl alcohol-based resin may be formed into a film and used as a polarizer. A method for forming a film of the polyvinyl alcohol-based resin is not particularly limited, and various methods known in the art may be used. For example, the process of uniaxially stretching a polyvinyl alcohol-type resin film; dyeing the stretched film with a dichroic dye to adsorb the dye; a process of treating the dye-adsorbed film with an aqueous solution of boric acid; And it can be manufactured through a process of washing with water. At this time, as the dichroic dye, iodine or dichroic organic dye can be used.

It is preferable that the surface of the polarizer is modified by at least one of corona treatment or plasma treatment. Through the corona treatment or plasma treatment, foreign substances on the surface of the polarizer may be removed, and coating properties may be increased. If the surface of the polarizer is not modified, coating properties and the like may be deteriorated, and residues and stains of the adhesive may occur during the peeling process.

The thickness of the polarizer according to the present invention may be 4 to 40 μm, preferably 8 to 25 μm. When the thickness of the polarizer is less than 4 μm, there is a problem of insufficient fairness and mass productivity during the polarizer stretching process, and when it exceeds 40 μm, there is a problem that the thinning of the polarizing plate cannot be achieved.

protective film

The protective film according to the present invention may be divided into a first protective film and a second protective film, and in the present specification, the first protective film and the second protective film are used to clarify the difference according to the composition and peeling method of the protective film and adhesive. The first protective film may be an upper protective film, or the second protective film may be an upper protective film, depending on the viewing angle, but is not limited thereto. However, the first protective film and the second protective film should be coupled to opposite surfaces of the polarizer.

The first or second protective film is a film capable of being separated from the polarizing plate in a subsequent process together with the following adhesive by bonding to the opposite side of the polarizer, respectively,

It is a film for protecting the surface of the polarizing plate from damage or abrasion when storing and transporting the polarizing plate, or handling the polarizing plate, such as when attaching it to a liquid crystal cell or panel of an image display device.

When the protective film is peeled from the polarizer, the adhesive may be peeled from the polarizer together with the protective film while being attached to the protective film side.

The protective film according to the present invention is not particularly limited as long as it is a resin film excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, and the like.

Specifically, as the protective film, a polyester-based resin film such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, which is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol;

Cellulose resin films, such as a diacetyl cellulose and a triacetyl cellulose;

Polycarbonate-type resin film which is a polymer which has a carbonate bond in a principal chain, and is obtained by condensation polymerization of bisphenol A and phosgene;

Acrylic resin films, such as polymethyl (meth)acrylate and polyethyl (meth)acrylate which are a homopolymer of methyl methacrylate, or a copolymer of methyl methacrylate and acrylic acid ester like methyl acrylate;

styrene-based resin films such as polystyrene and acrylonitrile-styrene copolymer;

polyolefin-based resin films such as cycloolefin, cycloolefin copolymer, polynorbornene, polypropylene, polyethylene, and ethylenepropylene copolymer;

vinyl chloride-based film; polyamide-based resin films such as nylon and aromatic polyamide;

other imide-based resin films; sulfone-based resin film; polyether sulfone-based resin film; polyether ketone-based resin film; sulfide polyphenylene-based resin film; vinyl alcohol-based resin film; vinylidene chloride-based resin film; vinyl butyral-based resin film; allylate-based resin film; polyoxymethylene-based resin film; urethane-based resin film; epoxy resin film; Alternatively, a silicone-based resin film or the like may be used.

The first protective film and the second protective film may use the same or different types of resin films.

The thickness of the protective film according to the present invention may be 10 to 100 μm, preferably 25 to 40 μm. When the thickness of the protective film is less than 10 μm, when it is used as the first protective film, problems such as wrinkles or stains due to overdrying during bonding of the polarizing plate may occur, and when used as the second protective film, an adhesive composition is applied In doing so, problems with coating defects such as linear stains and dewetting may occur. If it exceeds 100 μm, drying may not be easy and stains may occur due to residual moisture.

The first or second protective film may be each independently a single layer or a multilayer film. Functional layers such as a hard coating layer, an anti-glare layer, an anti-reflection layer, and a luminance enhancing layer may be formed on the surface to which the protective film and the polarizer do not adhere, and it is preferable to form a hard coating layer. When the hard coating layer is formed, cracks or damage on the surface of the protective film can be prevented, hardness and slip properties are improved, and cracks or stains of the polarizer can be more effectively prevented in the peeling process.

The said hard-coat layer can be formed by apply|coating resin materials, such as a silicone resin, an acrylic resin, a urethane acrylate resin, or the resin which mixed the filler on a protective film. The hard coat layer can be formed by coating and curing the resin by a known method such as a spin coating method or a micro gravure coating method.

first adhesive

The first adhesive (Adhesives) is used for bonding or bonding the polarizer and the first protective film, and may be peeled off together with the protective film when the protective film is peeled off.

As the first adhesive used for bonding the first protective film and the polarizer, an ordinary adhesive may be used, but a water-based adhesive is preferable.

Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, water-based polyesters, and water-based two-part urethane-based emulsion adhesives. The water-based adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains 0.5 to 60% by weight of solid content. Especially, deionized water or polyvinyl alcohol-type resin aqueous solution is preferable.

In the polyvinyl alcohol-based resin used as an adhesive, in addition to the vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, vinyl alcohol obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith. copolymers, and modified polyvinyl alcohol-based polymers in which hydroxyl groups are partially modified. In addition, a polyhydric aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconia compound, a zinc compound, and the like may be added to the water-based adhesive as additives.

The viscosity of the adhesive may be 5 to 100 cP. When included in the above range, spreadability on the surface of the polarizer is secured, so that fairness can be secured in a slit coater, a slit die coater, and the like.

The thickness of the adhesive is not particularly limited, but may preferably be 10 nm to 200 nm.

Application of the adhesive may be performed on either the protective film or the polarizer, or on both of them, and in general, a drying treatment is performed after bonding to form an adhesive layer including the applied dry layer.

The bonding method between the polarizer and the protective film using an adhesive is not particularly limited, and for example, the polarizer and/or the protective film may be coated by a casting method, a Mayer bar coating method, a gravure coating method, a die coating method, an immersion coating method, or a spraying method. The method of apply|coating an adhesive agent to an adhesive surface and overlapping both is mentioned.

second adhesive

The second adhesive is used for bonding or bonding the polarizer and the second protective film, and may be peeled off together with the protective film when the protective film is peeled off.

The second adhesive according to the present invention is a 'variable adhesive', has a composite property of reacting to both heat and ultraviolet (UV), and is characterized in that the adhesive force can be changed according to the curing process. Specifically, the second adhesive is a variable adhesive, characterized in that the adhesion is increased during thermal curing, and the adhesion is reduced when irradiated with ultraviolet (UV) rays.

The second adhesive according to the present invention may include a reactive resin prepared by copolymerizing a (meth)acrylic ester monomer or a vinyl carboxylate monomer. The reactive resin may have complex properties including both photoreactivity and thermal reactivity.

The (meth)acrylic ester monomer may be, for example, an alkyl (meth)acrylate containing a linear or branched alkyl group having 1 to 14 carbon atoms, specifically methyl (meth)acrylate, ethyl (meth) ) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl ( meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, It may include one selected from the group consisting of isononyl (meth) acrylate and combinations thereof.

Examples of the vinyl carboxylate monomer include vinyl acetate and vinyl butyrate, and the vinyl carboxylate monomer may be polymerized with a polymerizable monomer having a crosslinkable functional group.

Examples of the polymerizable monomer having a crosslinkable functional group include glycidyl methacrylate, which is an unsaturated monomer having a glycidyl group;

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, N -ethylenically unsaturated monomers having a hydroxyl group such as hydroxyethyl (meth)acrylates such as hydroxyethyl acrylamide;

Styrene, vinyltoluene, α-methylstyrene, p-chlorostyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-vinylbenzylmethyl ether, m-vinylbenzylmethyl ether, p-vinyl aromatic vinyl compounds such as benzyl methyl ether, o-vinyl benzyl glycidyl ether, m-vinyl benzyl glycidyl ether, and p-vinyl benzyl glycidyl ether;

N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N-o-hydroxyphenylmaleimide, N-m-hydroxyphenylmaleimide, N-p-hydroxyphenylmaleimide, N-o-methylphenylmaleimide, N-m -N-substituted maleimide compounds, such as methylphenylmaleimide, N-p-methylphenylmaleimide, N-o-methoxyphenylmaleimide, N-m-methoxyphenylmaleimide, and N-p-methoxyphenylmaleimide;

Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, alkyl (meth)acrylates such as sec-butyl (meth)acrylate and t-butyl (meth)acrylate; Cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methylcyclohexyl (meth) acrylate, tricyclo [5.2.1.0 2,6 ] decan-8-yl (meth) acrylate, 2- alicyclic (meth)acrylates such as dicyclopentanyloxyethyl (meth)acrylate and isobornyl (meth)acrylate;

aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate;

3-(methacryloyloxymethyl)oxetane, 3-(methacryloyloxymethyl)-3-ethyloxetane, 3-(methacryloyloxymethyl)-2-trifluoromethyloxetane; 3-(methacryloyloxymethyl)-2-phenyloxetane, 2-(methacryloyloxymethyl)oxetane, 2-(methacryloyloxymethyl)-4-trifluoromethyloxetane, etc. of unsaturated oxetane compounds; and the like, but is not limited thereto, and these may be used alone or in combination of two or more.

In one embodiment, the second adhesive including a reactive resin prepared by copolymerizing the (meth)acrylic ester monomer or carboxylate vinyl monomer according to the present invention may be a compound represented by Formula 1.

[Formula 1]

In Formula 1, R1 is a straight-chain or branched alkyl group having 1 to 14 carbon atoms, n, m and l are mole fractions of each monomer, respectively, n is 70 to 95, m is 4.5 to 29.9, l is 0.1 to 0.5 can be

The viscosity of the second adhesive is preferably 500 to 1,500 cP, and can be adjusted by mixing the reactive resin and a solvent. When the viscosity of the second adhesive is less than 500 cP, it may be difficult to secure coating properties in methods such as slit coater, slit die coater, and gravure coating. Coating defects may occur.

In addition, the reactive resin may be included in an amount of 20 to 50 parts by weight, preferably 30 to 40 parts by weight, based on the total weight of the second adhesive. When included in the above viscosity and content range, spreadability on the surface of the polarizer is secured, so that fairness can be secured in a slit coater, a slit die coater, and the like.

In addition, the weight average molecular weight of the reactive resin (eg, measured by gel permeation chromatography (GPC) using polystyrene as a standard material) may be about 10,000 to 90,000, preferably 50,000 to 80,000. If the weight average molecular weight is less than 10,000, the viscosity of the variable adhesive may decrease, and defects may occur in the coating or coating process due to the low viscosity. can do. If the weight average molecular weight is more than 90,000, the viscosity of the variable adhesive may be too high, and thus process defects may occur depending on the type of coating or coating, and difficulty in controlling the solid content of the adhesive composition may occur.

In addition, it is preferable that the acid value of the reactive resin is 3 mgKOH/g or more. When the acid value is 3 mgKOH/g or more, the tackiness of the surface of the adhesive is increased, so that the peeling force of the release film can be increased, and the reactivity of the adhesive composition can be increased to accelerate gelation after mixing the composition.

The solvent is preferably methyl ethyl ketone or ethyl acetate, but is not particularly limited as long as it dissolves the second adhesive.

In addition, ethers, aromatic hydrocarbons, ketones, alcohols, esters or amide solvents can be further used. Specifically, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol di Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dipropyl ether and dipropylene glycol ethers such as dibutyl ether; aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene; ketones such as methyl ethyl ketone, acetone, methyl amyl ketone, methyl isobutyl ketone and cyclohexanone; alcohols such as ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol and glycerin; 3-ethyl 3-ethoxypropionate, 3-methoxymethyl propionate, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, butyl acetate, amyl acetate, methyl lactate, ethyl lactate, butyl lactate, 3-methyl Toxybutyl acetate, 3-methyl-3-methoxy-1-butyl acetate, methoxypentyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol Esters such as monoacetate, diethylene glycol diacetate, diethylene glycol monobutyl ether acetate, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol monoethyl ether acetate, ethylene carbonate, propylene carbonate and γ-butyrolactone, etc. can be heard The solvent may be used alone or in a mixture of two or more selected from the group consisting of the exemplified solvents.

The second adhesive has an adhesive force of 3.0 N/25 mm or less, preferably 1-3 N/25 mm, more preferably 2-3 N/ It can exhibit a high adhesion of 25mm, and then when subjected to a UV curing process, 0.35 N/25mm or less, preferably 0.01 to 0.35 N/25mm, more preferably 0.01 to 0.1 N/25mm, most preferably 0.01 to 0.05 N/25mm may have an adhesive force. As the range of change in adhesion is satisfied, the protective film does not float on the polarizing plate even when stored for a long period of time, so storage stability is excellent, adhesive residues or stains after peeling do not occur, and double-sided peeling problems among the protective films on both sides It is possible to provide the effect of effectively peeling off only the desired protective film on one side without the need.

In addition, in the case of the second adhesive, a photopolymerization initiator, a crosslinking agent, etc. other than the reactive resin and solvent may be further included.

The photopolymerization initiator may serve to facilitate the peeling process by reducing the adhesive strength of the adhesive during UV curing by performing a curing reaction with the reactive resin.

The photopolymerization initiator is typically an acetophenone-based compound, a benzophenone-based compound, a biimidazole-based compound, a triazine-based compound, an oxime ester-based compound, and a thioxanthone-based compound.

Specific examples of the acetophenone-based compound include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 2-hydroxy-1-[4-(2-hydroxyl) oxyethoxy)phenyl]-2-methylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one; 2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1 -one, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, etc. are mentioned.

Examples of the benzophenone-based compound include benzophenone, methyl O-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3',4,4'-tetra( tert-butylperoxycarbonyl)benzophenone and 2,4,6-trimethylbenzophenone.

Specific examples of the biimidazole compound include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3-dichloro Phenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetra(alkoxyphenyl)biimidazole , 2,2'-bis (2-chlorophenyl) -4,4', 5,5'-tetra (trialkoxyphenyl) biimidazole, 2,2-bis (2,6-dichlorophenyl) -4, 4'5,5'-tetraphenyl-1,2'-biimidazole or the imidazole compound in which the phenyl group at the 4,4',5,5'-position is substituted by the carboalkoxy group, etc. are mentioned. Among them, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3-dichlorophenyl)-4,4' ,5,5'-tetraphenylbiimidazole and 2,2-bis(2,6-dichlorophenyl)-4,4'5,5'-tetraphenyl-1,2'-biimidazole are preferably used do.

Specific examples of the triazine-based compound include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6 -(4-Methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-piperonyl-1,3,5-triazine, 2,4-bis (trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2- yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine , 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl )-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine etc. are mentioned.

The oxime ester compound is o-ethoxycarbonyl-α-oxyimino-1-phenylpropan-1-one, 1,2-octadione,-1-(4-phenylthio)phenyl,-2-(o -benzoyloxime), ethanone,-1-(9-ethyl)-6-(2-methylbenzoyl-3-yl)-,1-(o-acetyloxime), etc. 124 (Shiva Geigisa), CGI-224 (Chiba Geigisa), Irgacure OXE-01 (BASF), Irgacure OXE-02 (BASF), N-1919 (Adecas), NCI-831 (Adecas), etc. can be heard

Examples of the thioxanthone-based compound include 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and the like. There is this.

The photopolymerization initiator may be added in an amount of 0.1 to 3.0 parts by weight based on 100 parts by weight of the reactive resin. When the photopolymerization initiator is included in an amount exceeding 3 parts by weight, an additional reaction of the adhesive may proceed by an external light source such as a fluorescent lamp or sunlight, and storage stability may be adversely affected.

As the crosslinking agent, a polyisocyanate-based, aziridine-based, or epoxy-based crosslinking agent may be used, and preferably, an aziridine-based crosslinking agent may be included. In addition, the crosslinking agent may be used alone or in combination of two or more.

The polyisocyanate-based crosslinking agent is a compound having two or more isocyanate functional groups, and includes, for example, aromatic polyisocyanates such as tolylene diisocyanate diphenylmethane diisocyanate and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; Alicyclic polyisocyanates, such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, etc. are mentioned, These biuret form, isocyanurate form, or these with ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane. , and an adduct body which is a reaction product of a low-molecular active hydrogen-containing compound such as castor oil.

The aziridine-based crosslinking agent is, for example, trimethylolpropane tri[3-(1-aziridinyl)propionate], trimethylolpropane-tris-(beta-N-aziridinyl)propionate, trimethylol Propane tris(2-methyl-1-aziridinepropionate), 2-methylaziridine, lithium L-aziridine-2-carboxylate, N-tosylaziridine, 1-(2-cyanoethyl)aziri Dean, 1-(benzylsulfonyl)aziridine, 1-(p-tosyl)aziridine 1-phenylmethanesulfonylaziridine, pentaerythritol-tris-(β-(N-aziridinyl)propionate, etc. can be heard

The epoxy-based crosslinking agent is, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylene Diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, etc. are mentioned.

In addition, the crosslinking agent may further include (meth)acrylate containing an ethylene oxide group. As the (meth)acrylate containing the ethylene oxide group, AM90G (methoxypolyethylene glycol acrylate) (EO 9.0 mol), M130G (methoxypolyethylene glycol methacrylate) (EO 13 mol), M230G manufactured by Shin-Nakamura Chemical Co., Ltd. (methoxypolyethylene glycol methacrylate) (EO 23 mol) and the like, and according to an embodiment of the present invention, M130G may be preferably used.

The crosslinking agent may be added in an amount of 6 to 10 parts by weight based on 100 parts by weight of the reactive resin. When the content of the crosslinking agent is less than the above range, adhesion may be reduced, and if the content exceeds the above range, the crosslinking reaction may occur excessively, and problems such as deterioration of durability and storage stability may occur.

In the case of a polarizing plate comprising a protective film according to the present invention, the difference between the adhesion of the first protective film to the polarizer and the adhesion of the second protective film to the polarizer is 0.1 N/25mm or more, preferably 1 N/25mm or more. have.

The adhesion of the first surface using the first protective film and the first adhesive may be 0.05 to 0.35 N/25 mm, preferably 0.1 to 0.2 N/25 mm. If the adhesion is less than 0.05 N/25mm, the protective film may float during storage, which may cause difficulties in the next process, and if the adhesion exceeds 0.35 N/25mm, peeling failure may occur.

The adhesion of the second surface using the second protective film and the second adhesive may have an adhesion of 3.0 N/25 mm or less before photocuring, preferably 1.0 to 3.0 N/25 mm, and more preferably 2 to 3 It can be N/25mm. After photocuring, it may have an adhesion of 0.35 N/25mm or less, preferably 0.01 to 0.35 N/25mm, more preferably 0.01 to 0.1 N/25mm, and most preferably 0.01 to 0.05 N/25mm. As the adhesion range is satisfied, the problem of peeling both sides of the protective film can be suppressed due to the difference in adhesion between the two protective films, and there is an advantage in that only a desired protective film can be peeled off in the product manufacturing process.

<Peeling method of protective film>

In addition, the present invention provides a method of peeling a protective film from a polarizing plate including a structure in which a first protective film, a polarizer, and a second protective film are sequentially stacked.

In the peeling method of the protective film, the content of the polarizer, the protective film and the adhesive may be applied as it is described in the <polarizing plate>.

In the peeling method of the protective film of the present invention, the structure and components of the protective film, polarizer, hard coating layer, adhesive, etc., and the manufacturing method thereof are not particularly limited as long as they do not interfere with the technical characteristics described above, Those known in the art may be employed without limitation.

A method for peeling a protective film according to the present invention,

1) surface modification of the polarizer;

2) bonding the polarizer to the first protective film and the second protective film using a first adhesive and a second adhesive, respectively; and

3) irradiating ultraviolet (UV) light on the second protective film to peel the second protective film from the polarizer.

Hereinafter, each step will be described in detail.

In the 1) step of surface-modifying the polarizer ,

The surface modification may be made through corona or plasma treatment on the surface of the polarizer, remove foreign substances on the surface of the polarizer, and increase coating properties. If the surface of the polarizer is not modified, coating properties and the like may be deteriorated, and residues and stains of the adhesive may occur during the peeling process.

Corona treatment involves applying a high voltage between an electrode connected to a high voltage generator and a roll of dielectric, and placing or moving a polarizer into the corona discharge generated between the roll and the electrode. Usually, the frequency of the high voltage applied between the roll and the electrode is referred to as a discharge frequency, and the discharge frequency may be generally in the range of 50 Hz to 5,000 kHz, preferably in the range of 5 to several hundreds of kHz. If the discharge frequency is too low, the discharge is unstable, and a large number of pinholes may be formed on the surface of the polarizer.

Corona discharge treatment is easily performed under the atmosphere, but can be performed in a sealed or semi-sealed treatment apparatus filled with a gas other than air or filled with an air-polluted gas. Examples of the gas may include nitrogen gas, argon gas, and oxygen gas.

Plasma treatment used in the present invention can be performed by glow discharge, and in the above-mentioned glow discharge plasma generating apparatus, a polarizer intended to impart hydrophilicity is placed between counter electrodes, and a plasma excitatory gas is introduced between the electrodes at high frequency. The surface treatment can be performed by plasma excitation of the gas by applying a voltage to cause a glow discharge to be performed between the electrodes.

The plasma excitable gas refers to a gas excited by plasma, and includes argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, and the like.

The frequency of the applied high-frequency voltage is preferably 1 kHz or more and 100 kHz or less, and more preferably 1 kHz or more and 10 kHz or less.

In the 2) step of bonding the polarizer, the first protective film, and the second protective film with a first adhesive and a second adhesive, respectively ,

The bonding method between the polarizer and the protective film using an adhesive is not particularly limited, and for example, the polarizer and/or the protective film may be coated by a casting method, a Mayer bar coating method, a gravure coating method, a die coating method, an immersion coating method, or a spraying method. The method of apply|coating an adhesive agent to an adhesive surface, and sticking or crimping|bonding both is mentioned.

When the first protective film or the second protective film is composed of a plurality of layers, such as a release film, after the release film is removed, it may be combined with a polarizer using an adhesive.

In addition, as a method of bonding the polarizer and the protective film, a conventional adhesive or pressure-sensitive adhesive bonding method may be used, and preferably, the first protective film and the second protective film are compressed by the first adhesive and the second adhesive, respectively. As the method, a method of pressing by applying heat may be used, and specifically, a hot press method or the like may be used. In the case of the second adhesive, it may be more preferable to combine by applying heat and pressing.

In the case of attaching the adhesive by applying heat, high adhesion of the second adhesive, which is a variable adhesive, can be induced by heat curing, and thereafter, in shipping the first adhesive and the first protective film, which are conventional adhesives, double-sided peeling, etc. Problems can be prevented, and it can be advantageously used for the storage method of the protective film, which will be described later.

In the case of pressing by applying heat, the temperature of the heat treatment is preferably 80 to 100 °C, and the heat treatment time is preferably 2 to 4 minutes. If the heat treatment is performed at 80 ° C. or less than 2 minutes, the solvent volatilization is insufficient, causing stains on the polarizer or the adhesive (or adhesion) strength of the adhesive may decrease. This may occur, thereby reducing the uniformity of the thickness.

In addition, as long as the object of the present invention is not impaired, the second protective film may be bonded to only one surface of the polarizer by pressing the second protective film using the second adhesive, if necessary.

3) The step of peeling the second protective film from the polarizer by irradiating ultraviolet (UV) light on the second protective film is specifically,

3-1) peeling from the polarizer using the low adhesion of the first protective film;

3-2) It is preferable to irradiate the second protective film with ultraviolet rays (UV) to peel the second protective film.

In addition, after peeling each protective film from the polarizer, the step of bonding a PF or retardation film to each protective film surface may be further included.

In the case of the second protective film side containing the second adhesive according to the present invention, since it has very high adhesion before UV curing, the first protective film and the first adhesive including a conventional adhesive or pressure-sensitive adhesive before UV curing By pre-peeling, the problem of double-sided peeling or adhesive residue, etc. can be prevented. However, when UV curing is performed first and the second adhesive, which is a variable adhesive, is first peeled off, the difference in adhesion between the first protective film and the first protective film including the first adhesive, which is a conventional adhesive, is not large, so problems such as double-sided peeling may occur. It is not preferable to have

In addition, in the method of peeling the first protective film of the present invention, it is not particularly limited, but preferably, only the first protective film can be peeled by fixing the first protective film and folding the polarizer and the second protective film. .

When the first protective film is fixed and the polarizer and the second protective film are peeled off by folding the polarizer and the second protective film, the adhesion is lower than when the polarizer and the second protective film are fixed and the first protective film is folded and peeled. Since the protective film can be peeled off without applying a large pressure to the polarizing plate with less force, process stability can be secured, and the problem of staining of the polarizing plate can be solved by suppressing the generation of residues of the adhesive.

<Storage method of polarizer>

The present invention provides a method for storing a polarizing plate including a protective film.

In the storage method of the polarizing plate including the protective film, the content of the polarizer, the protective film, and the adhesive may be applied as it is described in the <polarizing plate>.

The storage method of the polarizing plate including the protective film according to the present invention may be applied when storing or transporting the polarizing plate in a roll form, and in the polarizing plate of the present invention, the high adhesion side is rolled inward and stored characterized in that

Specifically, when the polarizing plate is rolled and stored with the second protective film including the second adhesive having high adhesion as the inner surface, the efficiency is high in storage and transport, and the contraction of the protective film or the polarizer is prevented for a long period of time. Even in the case of storage, it is possible to provide an effect of suppressing defective problems such as floating, air bubbles, or moisture penetration between the respective components of the polarizing plate.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

<Manufacture of polarizing plate>

Preparation Example 1: Preparation of the second adhesive

Butyl acrylate monomer (butyl acrylate, BAM) 80 to 120 parts by weight, 2,3-epoxypropyl methacrylate (2,3-epoxypropyl methacrylate) 10 to 30 parts by weight, acrylic acid (AAc) or methacrylic acid (methacrylic acid, mAAc) 10-20 parts by weight, 2,2'-azobis(isobutyronitrile) (2,2'-azobis(isobutyronitrile), AIBN) 0.6-1.0 parts by weight, methyl ethyl ketone (Metyl ethyl) ketone, MEK) 100 to 200 parts by weight and methyl isobutyl ketone (MIBK) 60 to 80 parts by weight were mixed to prepare a copolymerized reactive resin. The prepared reactive resin had a weight average molecular weight of 80,000 and an acid value of 2.78 mgKOH/g. Thereafter, a reactive resin mixture was prepared by mixing 30 to 40 parts by weight of methyl ethyl ketone and a solid content of the reactive resin as a solvent, and the viscosity was measured to be 500 to 1,500 cP (25° C.).

In addition, based on 100 parts by weight of the prepared reactive resin mixture, 200 parts by weight of methyl ethyl ketone (MEK) as a solvent, 1 part by weight of I-184 (BASF) as a photoinitiator, and MC-A100 (AK) as a crosslinking agent Chemical Co.) 6 parts by weight and M130G (methoxypolyethylene glycol methacrylate, Shin-Nakamura Co.) 6 parts by weight as an additive were mixed to finally prepare a second adhesive, which is a variable adhesive.

Preparation Example 2: Preparation of a polarizing plate

Polarizing plates including protective films according to Examples and Comparative Examples were prepared according to the laminate structure shown in Table 1 below.

- TAC-HC: HC-40TAC composition (DNP company)

- TAC: Triacetyl Cellulose, the number in front of TAC indicates the thickness of the protective film.

- DIW: De-Ionized Water

- Z1: acetoacetyl group-modified polyvinyl alcohol-based resin (including Z200 solids 1%, Japan Synthetic Chemical Industry Co., Ltd.)

- Variable adhesive: the second adhesive according to Preparation Example 1

<Experimental example>

For the polarizing plates according to Examples and Comparative Examples, storage stability, peeling process stability, and quality evaluation of the polarizing plate after peeling off the protective film were performed, and the results are shown in Table 2 below. The measuring method and evaluation method used in the present invention are as follows.

1. Adhesion evaluation

For the prepared Examples and Comparative Examples, the adhesion of the protective film to the polarizer was measured.

Specifically, the adhesion strength is measured by cutting the finished polarizing plate into a width of 2.5 mm and a length of 20 cm or more based on the stretching direction of the polarizer to prepare a sample (Sample Precision Cutter, TOKO, TMC-600), and then attach the fixed surface to the glass with double-sided tape. The force measured while fixing and peeling the protective film to be peeled at 180° was evaluated. In this case, UTM equipment (Shimadzu, CA-210) was used.

2. Storage stability evaluation

The prepared Example and Comparative Example polarizing plates were cut to a width of 50 mm and a length of 300 mm using a precision sample cutter (TOKO, TMC-600). The prepared sample was adhered to a 3-inch core (outer diameter 90 mm), each end was fixed with tape, and the appearance of the sample was evaluated according to the following criteria after storage for 1 week and 1 month under constant temperature and humidity conditions (25° C., 55%).

<Evaluation criteria>

○: No defects such as air bubbles or floating in storage period of 1 week and 1 month, respectively

×: Defects such as bubbles and floating occurred in storage period of 1 week and 1 month, respectively

3. Evaluation of peeling process stability

The prepared Examples and Comparative Examples polarizing plates were cut to a width of 2.5 mm and a length of 20 cm using a precision sample cutter (TOKO, TMC-600). The adhesiveness of the upper and lower protective films was measured by the peeling method according to the present invention, and the stability in the peeling process was evaluated by evaluating whether double-sided peeling occurred.

<Evaluation criteria>

○: Adhesion 0.01 N/25mm or more and 0.50 N/25mm or less, no peeling on both sides.

×: Adhesion force less than 0.01N/25mm, more than 0.50N/25mm, double-sided peeling occurred.

4. Evaluation of Polarizer Quality

During the peeling process stability evaluation of the completed polarizer, the peeling surface was visually inspected to confirm whether there was any cloudiness such as adhesive residues or stains.

<Evaluation criteria>

○: No white turbidity such as stains

×: There is a cloudiness phenomenon such as unevenness

Referring to Table 2, as a result of removing the protective film according to the peeling method of the polarizing plate and the protective film comprising the protective film and the adhesive composition according to the present invention, the protective film does not float even after a long-term storage of 1 month or more, so storage stability It can be seen that this is excellent. In addition, it can be confirmed that the protective film and the adhesive are peeled cleanly without any residue or stain of the adhesive occurring during the peeling process, and it can be confirmed that the stability is further improved in the peeling process. This effect, in the case of the second adhesive, shows a very high adhesion of 2.0 N/25mm level before UV irradiation, while fixing the first protective film and peeling the polarizer and the second protective film by folding and peeling it shows low adhesion. It can be confirmed that peeling is effectively performed due to the difference in adhesion between the upper and lower protective films.

On the other hand, in Comparative Examples 1 and 2 in which surface modification (corona treatment) was not performed for the polarizer, there was a problem that a residue of the adhesive was generated, and in Comparative Examples 3 to 7 using a conventional adhesive as the second adhesive, storage The stability was poor, and problems such as staining or floating with the underlying substrate during the peeling process were confirmed.

Claims (14)

A polarizing plate comprising a structure in which a first protective film, a polarizer, and a second protective film are sequentially stacked,
a second adhesive for attaching the second protective film and the polarizer;
The second adhesive is a polarizing plate comprising a protective film, characterized in that the variable adhesive.
According to claim 1,
The second adhesive is a polarizing plate comprising a protective film, characterized in that the adhesion is increased during thermal curing, and the adhesion is reduced when irradiated with ultraviolet (UV).
According to claim 1,
The second adhesive is a polarizing plate comprising a protective film, characterized in that it comprises a reactive resin prepared by copolymerizing a (meth)acrylic ester monomer or a vinyl carboxylate monomer.
4. The method of claim 3,
The (meth)acrylic ester monomer is an alkyl (meth)acrylate containing an alkyl group having 1 to 14 carbon atoms, a polarizing plate comprising a protective film.
According to claim 1,
The second adhesive is a polarizing plate comprising a protective film, characterized in that it comprises a compound represented by the following formula (1):
[Formula 1]

In Formula 1,
R1 is a straight or branched chain alkyl group having 1 to 14 carbon atoms,
n, m and l are mole fractions of each monomer, respectively, n is 70 to 95, m is 4.5 to 29.9, and 1 is 0.1 to 0.5.
4. The method of claim 3,
A polarizing plate comprising a protective film, characterized in that the reactive resin has a weight average molecular weight of 10,000 to 90,000.
According to claim 1,
The second adhesive is a polarizing plate comprising a protective film, characterized in that the adhesion before UV curing is 1 to 3 N/25mm, and the adhesion after UV curing is 0.35 N/25mm or less.
According to claim 1,
A polarizing plate comprising a protective film, characterized in that the difference between the adhesion of the first protective film to the polarizer and the adhesion force of the second protective film to the polarizer is 1 N/25 mm or more.
A method of peeling a protective film from a polarizing plate comprising a structure in which a first protective film, a polarizer and a second protective film are laminated in order, the method comprising:
1) surface modification of the polarizer;
2) bonding the polarizer to the first protective film and the second protective film using a first adhesive and a second adhesive, respectively; and
3) The peeling method of the protective film, characterized in that it comprises the step of peeling the second protective film from the polarizer by irradiating ultraviolet (UV) on the second protective film.
10. The method of claim 9,
The surface modification in step 1), a method of peeling a protective film, characterized in that it is performed by any one or more methods of corona treatment or plasma treatment.
10. The method of claim 9,
Step 2) is a method of peeling a protective film, characterized in that by applying heat treatment to bond the polarizer and the second protective film with a second adhesive.
12. The method of claim 11,
The temperature of the heat treatment is 80 to 100 ℃ 2 to 4 minutes, characterized in that the treatment, the peeling method of the protective film.
10. The method of claim 9,
After irradiating ultraviolet (UV) light in step 3), the adhesive force between the second protective film and the polarizer is 0.35 N/25 mm or less.
As a storage method of a polarizing plate comprising the protective film according to any one of claims 1 to 8,
A method of storing a polarizing plate comprising a protective film, characterized in that the second protective film containing the second adhesive is stored as the inner surface.