KR20110068436A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE: A pressure-sensitive adhesive composition is provided to ensure excellent wettability to a material, releasability, high speed releasability and low speed releasability. CONSTITUTION: A pressure-sensitive adhesive composition has an interpenetrating polymer network structure after hardening and includes an acrylic resin and a thermal initiator in which 10 hours half-life temperature is 70 °C or less. The acrylic resin has average molecular weight of 1,000,000 or less. The acrylic resin is a polymer of alkyl (meth)acrylate and a monomer mixture including the alkyl (meth)acrylate. The thermal initiator is an azo-based initiator or peroxide-based initiator.

Description

Pressure-sensitive adhesive composition

The present invention relates to a pressure-sensitive adhesive composition, a protective film for an optical member, a manufacturing method of the pressure-sensitive adhesive, a polarizing plate and a liquid crystal display device.

A liquid crystal display is a device that displays an image by inserting a liquid crystal between two thin glass substrates. In the device, when a voltage is applied through an electrode connected to the liquid crystal, the molecular arrangement of the liquid crystal is changed, and thus, the rate of light passing through the liquid crystal is changed, thereby displaying a picture or color. The liquid crystal display device is a display device that is in the spotlight in various fields because of the low power consumption and the planar thinness.

As the demand for liquid crystal display devices increases, the demand for films having optical properties such as polarizing plates is increasing rapidly, and the speed of production of liquid crystal display devices is also required. In addition, as the production line speeds up, the demand for various raw subsidiary materials also increases, and the productivity of the raw subsidiary materials also becomes an important problem.

A protective film applied to an optical member such as a polarizing plate is usually manufactured by applying and drying the pressure-sensitive adhesive composition to a substrate and sequentially performing a process such as plywood, aging, inspection, slitting and packaging with a release film. In order to mature the pressure-sensitive adhesive in the step, it takes several tens of hours or more. The aging process is carried out for the reaction of the crosslinking agent and the adhesive resin blended in the pressure-sensitive adhesive composition, in this process the cohesion and durability of the pressure-sensitive adhesive is improved. Therefore, in order to manufacture an optical member such as a polarizing plate, in order to control the aging conditions as described above, a temperature and humidity control facility and space for the same are required, which causes an increase in processing cost and the like, which is a factor that lowers product competitiveness. have.

On the other hand, the protective film for the optical member is very important to control the adhesive force according to the peel rate. For example, in the case of manufacturing a polarizing plate, in order for the protective film to play a role, an appropriate low-speed peeling force is required. If the peeling force is too low, after the protective film is attached, moisture or bubbles or polarization on the surface or inside of the adherend is polarized. Lifting phenomenon is likely to occur due to shrinkage of the film. In addition, when the low-speed peeling force is low, the protective film of the cut surface is easily lifted during cutting, and is easily left to contamination from the outside.

In addition, in order to inspect the foreign material on the polarizing plate, when the protective film is peeled off and confirmed, it is necessary to be excellent in the property of wetting the adherend again upon reattachment.

In addition, in the case of manufacturing a liquid crystal display by attaching a polarizing plate, the protective film finally attached to the polarizing plate is removed, and at this time, the protective film is peeled off at high speed in terms of productivity. In this case, if the adhesive force is high during high-speed peeling, the thin liquid crystal panel is easily damaged, and the degree of static electricity is generated so that the driving device of the panel is lost.

Therefore, the pressure-sensitive adhesive of the protective film used for the optical member such as a polarizing plate exhibits a moderate low-speed peeling force, excellent wettability, it is necessary to adjust the properties to show a low peeling force at high peeling.

In general, the crosslinking degree of the pressure-sensitive adhesive for the protective film is set to be very high in order to control the adhesive force change according to the peeling speed. However, in the thermosetting adhesive, when the adhesive force according to the peeling rate is simply adjusted through the degree of crosslinking, the low speed and the high speed peeling force exhibit opposite results. Specifically, if the degree of crosslinking is lowered, the adhesive strength, in particular, the adhesive strength after heating is increased, and the peeling force is greatly increased at high speed peeling, while if the degree of crosslinking is high, the high-speed peeling force is low, but the low-speed peeling force is very low, and the wettability is poor. do.

As the prior arts, Japanese Patent Laid-Open Nos. Hei 5-163468 and Hei 11-256111 disclose an adhesive in which an epoxy crosslinking agent is added to a carboxyl group-containing acrylic copolymer to control gel content. However, in the case of the above technique, there is a problem that the balance of low speed and high speed peeling force is very poor.

Further, Japanese Patent Laid-Open No. 2001-323239 discloses a technique of lowering a high-speed peeling force by copolymerizing a (meth) acrylic acid ester having 12 or more carbon atoms of an alkyl group with a (meth) acrylic acid ester having 3 to 10 carbon atoms. However, the above technique has a problem in that the glass transition temperature of the copolymer increases due to the long-chain alkyl group having 12 or more carbon atoms, the wettability decreases, and the adhesion to the substrate decreases.

In addition, Japanese Patent Laid-Open No. 2005-23143 discloses a technique for controlling the degree of crosslinking of an adhesive in order to adjust the peeling force of a protective film. However, when the degree of crosslinking in the thermosetting system as in the above technology is increased, the low-speed peeling force is also lowered along with the high-speed peeling force, making it difficult to perform the fundamental function of the protective film protecting the panel from external contamination.

An object of the present invention is to provide an adhesive composition, a protective film for an optical member, a manufacturing method of an adhesive, a polarizing plate, and a liquid crystal display device.

The present invention, as a means for solving the above problems, implements the interpenetrating polymer network (Interpenetrating Polymer Network) structure after curing,

It provides an adhesive composition comprising an acrylic resin and a thermal initiator having a half-life temperature of 10 hours or less.

The present invention as another means for solving the above problems, the base; And it is provided on one side or both sides of the base material, and provides a protective film for an optical member having a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition according to the present invention.

The present invention is another means for solving the above problems, the first step of applying a coating liquid containing a pressure-sensitive adhesive composition according to the invention on the process substrate; A second step of drying the coating solution applied in the first step; And a third step of irradiating light to the coating liquid dried in the second step.

The present invention as another means for solving the above problems, provides a polarizing plate attached to one or both surfaces of the protective film according to the present invention.

As another means for solving the above problems, the present invention provides a liquid crystal display device comprising a liquid crystal panel in which the polarizing plate of the present invention is attached to one side or both sides.

In this invention, the adhesive which is excellent in the wettability and re-peelability with respect to a base material, is excellent in the balance of the low speed and high speed peeling force, and does not cause contamination of a to-be-adhered body after peeling. In addition, in the present invention, it is possible to provide a pressure-sensitive adhesive that significantly shortens the aging time in the pressure-sensitive adhesive manufacturing process, but does not cause a change in the adhesive properties with time after manufacture, that is, a change over time.

The present invention implements an interpenetrating polymer network (hereinafter sometimes referred to as "IPN") structure after curing,

It is related with the adhesive composition containing acrylic resin and the thermal initiator whose half life temperature of 10 hours is 70 degrees C or less.

The pressure-sensitive adhesive composition of the present invention can be effectively used for, for example, an optical member (ex. Polarizing plate) protective film.

Hereinafter, the pressure-sensitive adhesive composition of the present invention will be described in detail.

The pressure-sensitive adhesive composition of the present invention implements the IPN structure after curing, that is, in the cured state. The term "cured state of the adhesive composition" used in the present specification means a state in which the composition of the present invention is manufactured in the form of an adhesive through light irradiation, heating, drying, or aging. The term "light irradiation" used in the present invention refers to irradiation of electromagnetic waves that can cause a polymerization reaction by affecting a photoinitiator or a polyfunctional acrylate and the like, wherein the electromagnetic waves are microwaves, infrared rays (IR), ultraviolet rays ( UV, X-rays and γ-rays, as well as particle beams such as α-particle beam (α-particle beam), proton beam (neuton beam), neutron beam (electron beam) and electron beam (electron beam) Used.

In addition, the term "IPN structure" used in the present invention means a case where two or more crosslinked structures are simultaneously implemented in the pressure-sensitive adhesive. For example, the acrylic resin included in the pressure-sensitive adhesive composition of the present invention can impart a crosslinked structure to the pressure-sensitive adhesive through a crosslinking reaction induced by a thermal initiator. In this case, when the composition further includes a component that may cause a crosslinking reaction or a polymerization reaction separate from the reaction of the acrylic resin and the thermal initiator, such as a multifunctional acrylate and a radical polymerization initiator, after curing, Two or more crosslinked structures may coexist in the pressure-sensitive adhesive. As a component capable of imparting an additional crosslinked structure to the pressure-sensitive adhesive as described above, polyfunctional acrylates and radical polymerization initiators are exemplified, but the components that can implement the IPN structure in the present invention are not limited thereto.

The pressure-sensitive adhesive composition of the present invention includes an acrylic resin and a thermal initiator, and the acrylic resin may impart a crosslinked structure to the pressure-sensitive adhesive through a crosslinking reaction by the thermal initiator.

Generally, in the case of the existing pressure-sensitive adhesive, a crosslinkable functional group is given to an acrylic resin, and it is blended with a multifunctional crosslinking agent such as an isocyanate or an epoxy compound to give a crosslinking structure through the reaction of the crosslinkable functional group and the crosslinking agent. However, in the case of the existing pressure-sensitive adhesive as described above, an excessive crosslinking agent is required for adjusting the peeling force balance of the pressure-sensitive adhesive sheet, and thus, it takes a long time for the aging to terminate the change over time of the adhesive force and to secure a stable peeling force.

In the case of the present invention, thermal initiators that can be activated at sufficiently low temperatures are used to induce a crosslinking reaction of the subject. That is, in the present invention, the thermal initiator is activated during the drying of the pressure-sensitive adhesive to generate radicals, and the generated radicals attack radicals having a relatively weak bonding force such as a skeleton or side chain in the main chain (acrylic resin). It occurs serially. In the present invention, through the reaction of the generated radicals, the acrylic resin as a main material can quickly implement a crosslinked structure.

The acrylic resin used in the present invention may have a weight average molecular weight of 1 million or less. In the above, the weight average molecular weight of acrylic resin means the polystyrene conversion value measured by GPC (gel permeation chromatography). If the weight average molecular weight of the acrylic resin in the present invention exceeds 1 million, there is a fear that the durability and workability of the pressure-sensitive adhesive and the like. In the present invention, the lower limit of the weight average molecular weight of the acrylic resin is not particularly limited. In the present invention, the weight average molecular weight can be controlled in a range of 200,000 or more, for example, in consideration of the cohesive force of the pressure-sensitive adhesive.

In the present invention, the specific composition of the acrylic resin is not particularly limited. In the present invention, for example, the acrylic resin may be a polymer of a (meth) acrylic acid ester monomer or a polymer of a monomer mixture containing a (meth) acrylic acid ester monomer.

The kind of the (meth) acrylic acid ester monomer that can be used in the present invention is not particularly limited, and may be, for example, alkyl (meth) acrylate. In this case, when the alkyl group contained in the alkyl (meth) acrylate becomes too long, the cohesion force of the pressure-sensitive adhesive may be lowered, or the glass transition temperature (T _g ) or the adhesion may become difficult to be controlled. Preferably, an alkyl (meth) acrylate having an alkyl group of 4 to 12 is used. Examples of such monomers include 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, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate And, in the present invention, one kind or a mixture of two or more of the above can be used.

In the present invention, the acrylic resin may be provided with a crosslinkable functional group as necessary. In this case, the acrylic resin may be a polymer of a monomer mixture including a (meth) acrylic acid ester monomer and a crosslinkable monomer.

Examples of the crosslinkable monomer that can be used in the present invention include hydroxy group-containing monomers, carboxyl group-containing monomers and nitrogen-containing monomers. In the present invention, it is particularly preferable to use a hydroxy group-containing monomer among the crosslinkable monomers, but is not limited thereto. Specific examples of the hydroxy group-containing monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth). ) Acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate or 2-hydroxypropylene glycol (meth) acrylate, and the like. Examples of the carboxyl group-containing monomers Is (meth) acrylic acid, 2- (meth) acryloyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, acrylic acid duplex, itaconic acid, maleic acid And maleic anhydride. Examples of the nitrogen-containing monomer include (meth) acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, but are not limited thereto. In the present invention, a mixture of one or more of the above can be used.

In the present invention, when the monomer mixture includes a crosslinkable monomer, the monomer mixture is, for example, 80 parts by weight to 99.8 parts by weight of the aforementioned (meth) acrylic acid ester monomer and 0.01 parts by weight to 3 parts by weight of the crosslinkable monomer. It may include wealth.

When the monomer mixture of the present invention contains a crosslinkable monomer, if the content of the (meth) acrylic acid ester monomer is less than 80 parts by weight, the initial adhesive strength of the pressure-sensitive adhesive may be lowered, and if it exceeds 99.8 parts by weight, the cohesion may be reduced. Due to this, there is a fear of problems in durability. In addition, when the content of the crosslinkable monomer in the monomer mixture is less than 0.01 part by weight, the durability of the pressure-sensitive adhesive may be lowered. When the content of the crosslinkable monomer is more than 3 parts by weight, the adhesiveness or peeling force may be lowered.

In the present invention, the acrylic resin may, if necessary, be a polymer of a monomer mixture containing an additional monomer in addition to the (meth) acrylic acid ester monomer described above. In this case, the monomer mixture may further include, for example, a compound represented by the following formula (1). The compound of Chemical Formula 1 may be added for the purpose of controlling the glass transition temperature of the pressure-sensitive adhesive and providing other functionalities.

[Formula 1]

Wherein R ₁ to R ₃ each independently represent hydrogen or alkyl, and R ₄ represents cyano; Phenyl unsubstituted or substituted with alkyl; Acetyloxy; Or COR ₅ , wherein R ₅ represents amino or glycidyloxy unsubstituted or substituted with alkyl or alkoxyalkyl.

Alkyl or alkoxy in the definition of R ₁ to R _{5 in} the above formula means alkyl or alkoxy having 1 to 8 carbon atoms, preferably methyl, ethyl, methoxy, ethoxy, propoxy or butoxy.

Specific examples of the monomer of Formula 1 include nitrogen-containing monomers such as (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide or N-butoxy methyl (meth) acrylamide; Styrene-based monomers such as styrene or methyl styrene; Glycidyl (meth) acrylate; Or a carboxylic acid vinyl ester such as vinyl acetate, or the like, or a heterogeneous compound, but is not limited thereto. When the monomer mixture of the present invention includes the compound of Formula 1, the content thereof may be 20 parts by weight or less relative to the content of the (meth) acrylic acid ester monomer or the crosslinkable monomer. When the content exceeds 20 parts by weight, there is a fear that the flexibility and / or peeling force of the pressure-sensitive adhesive is lowered.

In the present invention, the method for producing the acrylic resin using the monomer mixture is not particularly limited, and may be prepared using, for example, a general polymerization method such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization. . In the present invention, in particular, a solution polymerization method may be used, and solution polymerization is preferably performed at a polymerization temperature of 50 ° C. to 140 ° C. by adding an initiator in a state where each monomer is uniformly mixed. Examples of initiators that can be used in this process include azo initiators such as azobisisobutyronitrile or azobiscyclohexane carbonitrile; And / or conventional initiators such as peroxides such as benzoyl peroxide or acetyl peroxide, and the like, but may be used one or a mixture of two or more thereof, but is not limited thereto.

The adhesive composition of this invention contains a thermal initiator. In the present invention, the thermal initiator may generate radicals instantaneously by heat applied in the drying or aging process, and thus may cause a crosslinking reaction of the acrylic resin. The thermal initiator used in the present invention may have a half-life temperature of 10 hours or less, preferably 60 ° C. or less, more preferably 50 ° C. or less. In the present invention, the 10-hour half-life temperature of the thermal initiator is controlled to 70 ° C. or less, maintaining high decomposition efficiency in the drying or aging process of the adhesive, and effectively inducing the crosslinking reaction of the acrylic resin, while the thermal initiator remains after curing. It can prevent the point which causes the time-dependent change of adhesive peeling force. On the other hand, in the present invention, the lower limit of the 10-hour half-life temperature of the thermal initiator is not particularly limited. However, if the half-life temperature is too low for 10 hours, since a heterogeneous curing reaction or the like may be caused, the half-life temperature may be appropriately controlled in a range of 30 ° C. or more.

The kind of thermal initiator that can be used in the present invention is not particularly limited as long as it has a half-life temperature in the above-described range. In the present invention, for example, 2,2-azobis-2,4-dimethylvaleronitrile (V-65, manufactured by Wako), 2,2-azobisisobutyronitrile (V-60, Wako) (A)) or an azo initiator such as 2,2-azobis-2-methylbutyronitrile (V-59, Wako); Dipropyl peroxydicarbonate (Peroyl NPP, NOF (manufactured)), Diisopropyl peroxy dicarbonate (Peroyl IPP, NOF (manufactured)), Bis-4-butylcyclohexyl peroxy dicarbonate (Peroyl TCP, NOF (manufactured) )), Diethoxyethyl peroxy dicarbonate (Peroyl EEP, NOF (product)), diethoxyhexyl peroxy dicarbonate (Peroyl OPP, NOF agent), hexyl peroxy dicarbonate (Perhexyl ND, NOF agent) ), Dimethoxybutyl peroxy dicarbonate (Peroyl MBP, NOF (product)), bis (3-methoxy-3-methoxybutyl) peroxy dicarbonate (Peroyl SOP, NOF agent), hexyl peroxy pival Rate (Perhexyl PV, NOF), amyl peroxy pivalate (Luperox 546M75, Atofina), butyl peroxy pivalate (Perbutyl, NOF) or trimethylhexanoyl peroxide (Peroyl 355, NOF) Peroxy ester compounds such as (agent); Dimethyl hydroxybutyl peroxane neodecanoate (Luperox 610M75, Atofina), amyl peroxy neodecanoate (Luperox 546M75, Atofina) or butyl peroxy neodecanoate (Luperox 10M75, Atofina) Peroxy dicarbonate compounds such as; Acyl peroxides such as 3,5,5-trimethylhexanoyl peroxide, lauryl peroxide or dibenzoyl peroxide; Ketone peroxide; Dialkyl peroxides; Peroxy ketal; Or a mixture of one or more kinds of peroxide initiators such as hydroperoxide and the like.

In the present invention, the thermal initiator may be included in an amount of 0.1 parts by weight to 20 parts by weight, preferably 0.1 parts by weight to 10 parts by weight, and more preferably 0.5 parts by weight to 10 parts by weight, based on 100 parts by weight of the acrylic resin. have. In the present invention, when the content of the thermal initiator is less than 0.1 part by weight, it is difficult to express a sufficient gel content in the pressure-sensitive adhesive, there is a fear that the peel force is increased or the adhesion to the substrate is inferior. In addition, when the content of the thermal initiator exceeds 20 parts by weight in the present invention, there is a fear that the thermal initiator remains after curing, causing a change in the adhesive force over time.

The pressure-sensitive adhesive composition of the present invention may further include a polyfunctional acrylate and a radical polymerization initiator.

In the above polyfunctional acrylate, through the polymerization reaction by the polymerization initiator, may implement the IPN structure in the pressure-sensitive adhesive, and may serve to compensate for the gel (gel) content.

In the present invention, the kind of polyfunctional acrylate that can be used is not particularly limited. In the present invention, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylic Neopentylglycol adipate di (meth) acrylate, hydroxyl puivalic acid neopentylglycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, Caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (meth) acryloxy ethyl isocyanurate, allylated cyclohexyl di (meth) acrylate , Tricyclodecane dimethanol (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (Meth) acrylate, neopentylglycol-modified trimethylpropane di (meth) acrylate, adamantane di (meth) acrylate or 9,9-bis [4- (2-acryloyloxyethoxy) Difunctional acrylates such as phenyl] fluorene and the like; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide Trifunctional acrylates such as modified trimethylolpropane tri (meth) acrylate, trifunctional urethane (meth) acrylate or tris (meth) acryloxyethyl isocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; 5-functional acrylates, such as propionic acid modified dipentaerythritol penta (meth) acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomers and trimethylolpropane tri (meth) acrylate And 6 functional acrylates such as reactants, but are not limited thereto.

In the present invention, one or more kinds of the above-described multifunctional acrylates may be used in combination, or in particular, the use of an acrylate having a molecular weight of less than 1,000 and more than trifunctional is preferable in terms of more excellent durability, but not limited thereto. It doesn't happen.

In the present invention, in particular, as the multifunctional acrylate, it is preferable to use an acrylate including a cyclic structure and / or a urethane bond in the molecular structure. In this case, the ring structure included in the acrylate may be a carbocyclic structure or a heterocyclic structure; Or any of a monocyclic or polycyclic structure. Specifically, examples of the ring structure included in the multifunctional acrylate include a cycloalkyl ring structure having 3 to 12 carbon atoms, preferably 3 to 8 carbon atoms, such as cyclopentane, cyclohexane, or cycloheptane. One or more ring structures may be included in the acrylate, preferably 1 to 5, more preferably 1 to 3, and one or more hetero atoms such as O, S or N may also be included.

As a specific example of the polyfunctional acrylate containing a ring structure as mentioned above which can be used by this invention, the monomer which has isocyanurate structures, such as a tris (meth) acryloxy ethyl isocyanurate, isocyanurate Of modified urethane acrylates (e.g., isocyanate compounds having a ring structure in a molecule (ex. Isoborone diisocyanate) and acrylate compounds (e.g. trimethylolpropane tri (meth) acrylate or pentaerythritol tri (meth) acrylate) Reactants, etc.), but is not limited thereto.

In the pressure-sensitive adhesive composition of the present invention, the multifunctional acrylate may be included in an amount of 1 part by weight to 50 parts by weight, preferably 5 parts by weight to 40 parts by weight, based on 100 parts by weight of the aforementioned crosslinkable acrylic resin. In the present invention, when the content of the multifunctional acrylate is less than 1 part by weight, the gel content compensation effect is deteriorated, the peeling force may increase excessively, or the adhesion with the substrate may be deteriorated. There is a possibility that the wettability and adhesion to the substrate are inferior.

The kind of radical polymerization initiator that can be included in the pressure-sensitive adhesive composition of the present invention is not particularly limited as long as it can advance the polymerization reaction of the polyfunctional acrylate by light irradiation.

Specific examples of radical polymerization initiators that can be used in the present invention include benzoin, hydroxy ketone, amino ketone or phosphine oxide, and more specifically, benzoin, benzoin methyl ether, benzo Phosphorus ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-die Methoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-di Ethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2- Tyl thioxanthone, 2-chloro thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo [2-hydroxy- 2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide and the like, but are not limited thereto. In the present invention, one or more kinds of the above can be used.

In the present invention, the radical polymerization initiator may be included in an amount of 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the acrylic resin. In the present invention, when the content of the radical polymerization initiator is less than 0.1 part by weight, there is a fear that the polymerization or curing reaction may not be performed smoothly. When the content of the radical polymerization initiator exceeds 20 parts by weight, the remaining polymerization initiator causes a change in the adhesive over time. There is a risk of dropping.

The adhesive composition of this invention may further contain an antistatic agent with the above-mentioned component. Such an antistatic agent can prevent the damage of the apparatus by the static electricity which arises at the time of peeling of a protective film in a polarizing plate manufacturing process, etc., for example.

The specific kind of antistatic agent that can be used in the present invention is not particularly limited, and may be, for example, a metal salt containing an alkali metal cation or an alkaline earth metal cation. In this case, specific examples of the cation include lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium ion (Rb ⁺ ), cesium ion (Cs ⁺ ), beryllium ion (Be ^{2 +} ), Magnesium ions (Mg ²⁺ ), calcium ions (Ca ²⁺ ), strontium ions (Sr ²⁺ ) and barium ions (Ba ²⁺ ), and the like, or two or more kinds thereof. (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), cesium ion (Cs ⁺ ), beryllium ion (Be ²⁺ ), magnesium ion (Mg ²⁺ ), calcium ion (Ca ²⁺ ), and One or more ^{kinds of} barium ions (Ba ²⁺ ) may be used, and lithium ions (Li ⁺ ) are more preferable in terms of ion stability and mobility in the pressure-sensitive adhesive, but are not limited thereto.

In addition, in the present invention, the kind of anion included in the metal salt is not particularly limited, and examples thereof include fluoride (F ⁻ ), chloride (Cl ⁻ ), bromide (Br ⁻ ), iodide (I ⁻ ), perchlorate (ClO ₄ ^-), hydroxide (OH ^-), carbonate (CO ₃ ^2-), carboxylate ^{_{(ex CH 3 CO 2 -.}} ), an azide anion (N ₃ ^-), phosphate (HPO ₄ ^2- ), nitrate (NO ₃ ^-), sulfonate (SO ₄ ^2-), methyl benzene sulfonate _{(CH 3 (C 6 H 4} ) SO 3 -), p- toluenesulfonate (CH ₃ C ₆ H ₄ SO ₃ ^-), carboxymethyl sulfonate _{(COOH (C 6 H 4)} SO 3 -), sulfonate as a triple (CF ₃ SO ₂ ^-), benzo carbonate ^{_{(C 6 H 5 COO -)}} , acetate (CH ₃ COO ^-), a triple acetate (CF ₃ COO ^-), tetrafluoroborate (BF ₄ ^-), tetra-benzyl borate _{(B (C 6 H 5)} 4 -), phosphate (PF ₆ hexafluoro ^-), Trispentafluoroethyl trifluorophosphate (P (C ₂ F ₅ ) ₃ F ₃ ^- ) ^- ), Bis methane sulfonimide (N (SO ₂ CF ₃₎ trifluoroacetate ₂ ^-), bis-penta-fluoro-ethane sulfonimide _{(N (SOC 2 F 5)} 2 - methane carbonyl in), bis trifluoroacetate The imide _{(N (COC 2 F 5)} 2 -), bis-penta-fluoro-ethane-carbonyl imide _{(N (COC 2 F 5)} 2 -), bis perfluorobutane sulfonimide (N (SO ₂ C ₄ F _{9) 2} ^-), bis perfluoro butane carbonyl imide (N (COC ₄ F _{9) 2} ^-), tris trifluoromethane sulfonyl nilme lactide _{(C (SO 2 CF 3)} 3 -), and tris tree Fluoromethanecarbonylmethide (C (SO ₂ CF ₃ ) ₃ ⁻ ) is preferably selected from the group consisting of, but is not limited thereto.

In the present invention, it is particularly preferable to use an anion including a perfluoroalkyl group, which performs well the role of electron withdrawing and has excellent hydrophobicity among the anions, but is not limited thereto.

In the pressure-sensitive adhesive composition of the present invention, the metal salt may be included in an amount of 0.001 part by weight to 20 parts by weight, preferably 0.001 part by weight to 10 parts by weight, based on 100 parts by weight of the acrylic resin described above. In the present invention, if the content of the metal salt is less than 0.01 part by weight, the antistatic effect may be insignificant. If it exceeds 50 parts by weight, the compatibility with the cured product may be lowered, or the durability or transparency may be deteriorated.

The pressure-sensitive adhesive composition of the present invention may further include a chelating agent capable of forming a complex with the metal salt together with the metal salt as described above. Such a chelating agent forms a complex with a metal salt, so that even when a small amount of antistatic agent is added, excellent antistatic performance can be given while maintaining or improving the durability, transparency, workability, and the like of the cured product.

The specific kind of chelating agent that can be used in the present invention is not particularly limited as long as it can perform the above-described action. In the present invention, for example, as the chelating agent, polyalkylene oxide (ex. Polyethylene oxide, polypropylene oxide, polybutylene oxide or polypentylene oxide, etc.), polyalkylene oxide (ex. Polyethylene oxide) Fatty acid alkyl esters or polyalkylene oxides of polypropylene oxide, polybutylene oxide or polypentylene oxide (eg, polyethylene oxide, polypropylene oxide, polybutylene oxide or polypentylene oxide, etc.) Alkylene oxide compounds such as carboxylic acid esters; Ester compounds having at least one ether bond in a molecule disclosed in Korean Patent Laid-Open No. 2006-0018495 or an oxalate group-containing compound, diamine group-containing compound, polyvalent carboxyl group-containing compound or ketone group disclosed in Korean Patent Laid-Open Publication No. 2006-0128659 Containing compounds and the like can be used.

In addition, the content of the chelating agent in the present invention is also not particularly limited, and may be appropriately selected in consideration of the desired effect.

The pressure-sensitive adhesive composition of the present invention is also an acrylic low molecular weight, a silane coupling agent, a tackifying resin, an epoxy resin, a crosslinking agent, a curing agent, a foaming agent, an organic salt, an ultraviolet stabilizer, an antioxidant, within a range that does not affect the effect of the invention. It may further comprise one or more additives selected from the group consisting of colorants, reinforcing agents, fillers, antifoams, surfactants and plasticizers.

The present invention also provides a substrate; And it is formed on one or both sides of the base material, and relates to a protective film for an optical member having a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition according to the present invention.

As described above, the pressure-sensitive adhesive composition of the present invention can provide a pressure-sensitive adhesive excellent in wettability, re-peelability, low-speed peeling force and high-speed peeling force to the substrate while shortening the aging process time. Accordingly, the pressure-sensitive adhesive composition of the present invention can be effectively applied to various optical devices or parts, display devices or parts. In particular, transparent substrates; And a pressure-sensitive adhesive sheet made of the pressure-sensitive adhesive of the present invention formed on the transparent substrate, a surface protective film for protecting optical members such as polarizing plates, retardation plates, optical compensation films, reflecting sheets, and brightness enhancement films used in liquid crystal displays. Can be effectively used.

In addition, the use of the adhesive composition of this invention is not limited to the use mentioned above, Various industrial sheets, for example, a protective film, a cleaning sheet, a reflective sheet, a structural adhesive sheet, a photosensitive adhesive sheet, the adhesive sheet for lane display It can be effectively used for optical adhesive products or adhesives for electronic components. In addition, the pressure-sensitive adhesive composition of the present invention can be effectively applied to laminate products, multilayer commercial adhesive sheet products, medical patches, heat-activated pressure-sensitive adhesives and the like.

As the base material used in the protective film of the present invention, a general transparency film in this field may be used without limitation, and examples thereof include a polyester film (ex. Polyethylene terephthalate film, polybutylene terephthalate), and polytetrafluoroethylene film. And plastic films such as polyethylene films, polypropylene films, polybutene films, polybutadiene films, vinyl chloride copolymer films or polyimide films. Such a substrate may consist of a single layer, or two or more layers may be laminated, and in some cases, may further include a functional layer such as an antifouling layer or an antistatic layer. In the present invention, it is also possible to perform surface treatment such as primer treatment on one or both surfaces of the substrate from the viewpoint of improving the substrate adhesion.

In the present invention, the thickness of the base film is not particularly limited to be appropriately selected depending on the use, and can be formed in a thickness of usually 5 μm to 500 μm, preferably 10 μm to 100 μm.

In addition, the thickness of the pressure-sensitive adhesive layer included in the protective film of the present invention is not particularly limited, and may be, for example, 2 μm to 100 μm, preferably 5 μm to 50 μm. If the thickness of the pressure-sensitive adhesive layer is out of the above-described range, the formation of a uniform pressure-sensitive adhesive layer becomes difficult and there is a fear that the physical properties of the pressure-sensitive adhesive film become nonuniform.

In the present invention, the pressure-sensitive adhesive layer, it is preferable that the gel (gel) content represented by the general formula 1 is 90% to 99%.

[Formula 1]

Gel content = B / A × 100

In the general formula 1, A represents the mass of the pressure-sensitive adhesive, B represents the dry mass of the insoluble content of the pressure-sensitive adhesive after immersing the pressure-sensitive adhesive for 48 hours at room temperature with ethyl acetate.

In the present invention, if the gel content is less than 90%, the adhesive force may be excessively increased, and if it is more than 99%, the adhesive force may be excessively lowered.

The present invention also comprises a first step of applying a coating liquid containing the pressure-sensitive adhesive composition to the process substrate; A second step of drying the coating solution applied in the first step; And a third step of irradiating light to the coating liquid dried in the second step.

In the first step of the present invention, a coating liquid containing the pressure-sensitive adhesive composition of the present invention is applied to a process substrate. The coating solution may be a pressure-sensitive adhesive composition containing each of the above-described components, or may be a solution in which the viscosity is controlled by dispersing and dissolving the above in an appropriate solvent. In addition, the process substrate may be a substrate film constituting the protective film as described above, and in some cases may be a peelable substrate commonly used in this field.

In the first step of the present invention, the method of applying the coating solution to the process substrate is not particularly limited, and may be performed using, for example, conventional means such as a bar coater.

The second step of the present invention is a step of drying the coating liquid applied in the first step under appropriate conditions. Through such a drying process, the solvent contained in the coating solution may be dried and the thermal initiator may be activated to induce a crosslinking reaction of the acrylic resin.

In the present invention, the drying conditions of the second step are not particularly limited. In the present invention, for example, the drying process may be performed for 1 minute to 5 minutes at a temperature of 100 ℃ to 150 ℃. By controlling the conditions of the drying conditions in the above range, the drying of the solvent and the activation of the thermal initiator can be efficiently performed.

The third step of the present invention is a step of irradiating light to the coating liquid after or at the same time as the drying process, thereby inducing a polymerization reaction of a photocurable component such as polyfunctional acrylate.

In the third step of the present invention, the method of irradiating light is not particularly limited, and for example, high pressure mercury lamp, low pressure mercury lamp, hydrogen (deuterium) lamp, rare gas (ex. Xenon, argon, helium or neon, etc.). ) Light source such as a discharge lamp, a nitrogen laser, an excimer laser (ex. XeCl, XeF, KrF or KrCl, etc.), a hydrogen laser or a halogen laser. The kind of light source that can be used in the present invention is not limited to the above-described kind, and any kind can be used as long as the object of the present invention can be achieved.

In addition, the light irradiation conditions in the third step of the present invention is not particularly limited as long as it is controlled to sufficiently induce the polymerization reaction of the photopolymerizable group included in the composition, for example, having a wavelength of 400 nm to 10 nm Ultraviolet light may be used. In addition, the ultraviolet rays used in the step may have an illuminance of 200 mW / cm ² to 1,000 mW / cm ² . In addition, the ultraviolet light used in the step may have a light amount of 50 mJ / cm ² to 1500 mJ / cm ² . However, conditions such as illuminance or light quantity of the ultraviolet ray are not particularly limited and can be appropriately controlled in consideration of physical properties of the pressure-sensitive adhesive.

The present invention also relates to a polarizing plate attached to one or both surfaces of the protective film according to the present invention described above.

Polarizing plate to which the protective film of the present invention can be attached, for example, a polarizer; And it may have a structure including a protective film formed on one side or both sides of the polarizer. In addition, the polarizing plate of the present invention may further include one or more functional layers selected from the group consisting of a protective layer, a reflective layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancing film, as the case may be.

The kind of polarizer which comprises a polarizing plate in this invention is not specifically limited. For example, in this invention, the film manufactured by extending | stretching and manufacturing polarizing components, such as iodine or a dichroic dye, can be used for the film which consists of polyvinyl alcohol-type resin as a polarizer. As the polyvinyl alcohol-based resin, polyvinyl alcohol, polyvinyl formal, polyvinyl acetal or saponified product of ethylene vinyl acetate copolymer may be used. In addition, the polarizer thickness is not particularly limited, but may be formed in a conventional thickness.

In the polarizing plate of the present invention, the protective film which may be formed on one or both surfaces of the polarizer is a concept distinct from the above-described protective film for optical members of the present invention, and specific examples thereof include cellulose-based films such as triacetyl cellulose; Polyester film such as polycarbonate film or polyethylene terephthalate film; Polyether sulfone-based film; And / or polyolefin films such as polyethylene films, polypropylene films or polyolefin films having a cyclo or norbornene structure or ethylene-propylene copolymers. At this time, the thickness of the protective film is also not particularly limited, and may be formed in a conventional thickness.

The present invention also relates to a liquid crystal display device in which the polarizing plate according to the present invention is attached to one side or both sides of the liquid crystal panel.

The type of liquid crystal cell constituting the liquid crystal display device of the present invention as described above is not particularly limited, such as TN (Twisted Neumatic), STN (Super Twisted Neumatic), IPS (In Plane Switching) or VA (Vertical Alignment) method It includes all common liquid crystal cells. In addition, the kind and other manufacturing method of the other structure contained in the liquid crystal display device of this invention are not specifically limited, either, The general structure of this field can be employ | adopted and used without a restriction | limiting.

Hereinafter, the present invention will be described in more detail with reference to examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited to the following examples.

Example 1.

Production of Acrylic Resin

Includes 98 parts by weight of 2-ethylhexyl acrylate (2-EHA) and 2 parts by weight of 2-hydroxybutyl acrylate (2-HBA) in a 1 L reactor equipped with a refrigeration device for reflux of nitrogen gas and easy temperature control. A monomer mixture was administered. Subsequently, 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Thereafter, the temperature of the reactor was maintained at 60 ° C, 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and then reacted for 8 hours to produce a 500,000 acrylic resin having a weight average molecular weight.

Production of an adhesive sheet (protective film)

In 100 parts by weight of the acrylic resin prepared above, 10 parts by weight of polyfunctional acrylate (M300, manufactured by Miwon Co., Ltd.), 2 parts by weight of radical polymerization initiator (Igacure 651, manufactured by Ciba Chem), and a 10 hour half-life temperature As a thermal initiator at 50 ° C., 2 parts by weight of ethylhexyl peroxydicarbonate and 20 parts by weight of methyl ethyl ketone (MEK) were combined, sufficiently stirred and mixed to prepare a coating solution. Thereafter, the prepared coating solution was coated on a polyethylene terephthalate (PET) film, and dried in an oven at 140 ° C. for 3 minutes. Thereafter, in consideration of the type and content of the photopolymerizable compound (polyfunctional acrylate) and the photoinitiator included in the coating liquid, ultraviolet light (UV) is irradiated with a metal halide lamp under conditions in which sufficient polymerization reaction can occur, and the adhesive sheet Was prepared.

Example 2.

In the preparation of the pressure-sensitive adhesive composition, the same procedure as in Example 1 was carried out except that di-3-methoxy butyl peroxydicarbonate was used as a thermal initiator having a half-life temperature of 44 ° C for 10 hours. The adhesive sheet was manufactured by the method.

Example 3.

In preparing the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet was manufactured in the same manner as in Example 1, except that trimethylhexanoyl peroxide was used as a thermal initiator having a half-life temperature of 59 ° C. for 10 hours.

Comparative Example 1.

The same procedure as in Example 1 was carried out except that the polyfunctional acrylate, the radical polymerization initiator, and the peroxydicarbonate were not blended, and instead, an isocyanate-based curing agent was considered in consideration of the hydroxyl group contained in the acrylic resin, and thus a coating solution was prepared. The adhesive sheet was manufactured by the method.

Comparative Example 2

An adhesive sheet was prepared in the same manner as in Example 1 except that no thermal initiator (peroxy dicarbonate) was added.

Comparative Example 3

An adhesive sheet was prepared in the same manner as in Example 1, except that the coating liquid was prepared without blending the polyfunctional acrylate and the radical polymerization initiator.

Comparative Example 4

An adhesive sheet was prepared in the same manner as in Example 1, except that dibenzoyl peroxide having a half-life temperature of 73 ° C. as a thermal initiator was used.

About the adhesive sheet manufactured by the Example and the comparative example, the physical property was evaluated by the following method, and the result was put together in Table 1, and it described.

1. Measurement of gel fraction before and after ripening

The gel fraction of the pressure-sensitive adhesive prepared in Examples and Comparative Examples was measured by the following method. The gel fraction was measured by measuring the gel fraction of the adhesive immediately after leaving the prepared pressure sensitive adhesive sheet at room temperature for 1 day (initial gel fraction) and the gel of the pressure sensitive adhesive immediately after the prepared pressure sensitive adhesive sheet was aged at a temperature of 50 ° C. for 5 days. The fractions (gel fractions after aging) were measured respectively. In each case, the gel fraction was obtained by dipping about 0.3 g of the adhesive in a # 200 stainless steel wire and immersing it in 100 ml of ethyl acetate, storing for 3 days in a dark room at room temperature, then separating the insoluble fraction of the adhesive, The mass (dry mass) after drying for 4 hours in an oven at 70 ° C. was measured, and the gel fraction was measured by substituting this for the general formula (1).

2. Measurement of low speed and high speed peeling force

The pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were attached to TAC (triacetylcellulose, Japan FUJIFILM) and anti-glare layer (AG, Japan DNP, Inc.) with a roller of 2 Kg in accordance with JIS Z 0237. It was stored for 24 hours under the temperature of 23 ° C. and 65% relative humidity. Thereafter, using a tensile tester, the peeling force was measured while peeling the adhesive sheet at a peeling rate of 0.3 m / min (low speed peel force) and 30 m / min (high speed peel force) at a peel angle of 180 °, respectively. . The peel force was measured immediately after the prepared pressure sensitive adhesive sheet at room temperature for 1 day, immediately after aging for 7 days at room temperature, and immediately after aging for 5 days at a temperature of 50 ° C., respectively.

TABLE 1

Example Comparative example One 2 3 One 2 3 4 Gel
Fraction Early(%) 95 94 94 95 15 70 89 After aging (%) 96 94 96 99 17 73 96


foil
Lee
Force Room temperature
1 day
keep sleaze
Peel force (gf) TAC 9.0 9.4 8.6 7.4 23 27 16 AG 9.5 9.8 8.9 6.9 30 31 18 high speed
Peel force (gf) TAC 115 121 118 161 255 311 181 AG 120 125 126 148 280 341 198 Room temperature
7 days
ferment sleaze
Peel force (gf) TAC 8.5 9.2 8.1 3.9 27 25 14 AG 8.9 9.5 8.2 5.1 29 32 13 high speed
Peel force (gf) TAC 110 120 111 124 270 302 177 AG 116 123 112 115 310 323 169 50 ° C,
5 days
ferment sleaze
Peel force (gf) TAC 9.4 9.3 7.9 4.1 24 28 8.9 AG 9.2 9.7 8.1 5.3 25 32 9.7 high speed
Peel force (gf) TAC 105 114 110 129 220 281 123 AG 110 116 111 125 251 301 112

As can be seen from the results of Table 1, in the embodiment according to the present invention, while achieving a high gel content of the pressure-sensitive adhesive, it exhibited a high low-speed peeling force and a low fast peeling force for the TAC surface and AG surface . In addition, in the case of the embodiment, the ratio of the low-speed and high-speed peeling force of the pressure-sensitive adhesive (high-speed peeling force / low-speed peeling force) appeared in the range of 11 to 12, the balance of both was excellent, and the change of the adhesive properties over time (change over time) Was not induced either.

On the other hand, in Comparative Example 1 in which the crosslinking structure was implemented using a crosslinkable acrylic resin and a thermosetting agent (isocyanate crosslinking agent), the low-speed peeling force and the high-speed peeling force were too low. High-speed peeling force / low speed peeling force) is also a range of 21-31, and it can confirm that the balance of both is poor. In addition, in the case of the comparative example 1, the time-dependent change in which adhesive force falls with passage of time was observed. In addition, in Comparative Examples 2 and 3 which do not contain a thermal initiator or do not contain a polyfunctional acrylate, the gel of the pressure-sensitive adhesive was largely insufficient and exhibited an excessively high peeling force, when applied to a polarizing plate manufacturing process or the like. As a result, it could be expected that this would cause a big problem in productivity. In addition, in the case of Comparative Example 4 using a thermal initiator with a high 10-hour half-life temperature, it was confirmed that the low-speed and high-speed peeling force was high, or showed a problem that changes with time.

Claims (20)

After curing, implement the interpenetrating polymer network structure, Pressure-sensitive adhesive composition comprising an acrylic resin and a thermal initiator having a half-life temperature of 10 hours or less. The pressure-sensitive adhesive composition of claim 1, wherein the acrylic resin has a weight average molecular weight of 1 million or less. The pressure-sensitive adhesive composition of claim 1, wherein the acrylic resin is a polymer of a monomer mixture comprising alkyl (meth) acrylate or alkyl (meth) acrylate. The pressure-sensitive adhesive composition of claim 1, wherein the thermal initiator has a half-life temperature of 60 ° C. or less for 10 hours. The pressure-sensitive adhesive composition of claim 1, wherein the thermal initiator is an azo initiator or a peroxide initiator. The pressure-sensitive adhesive composition of claim 1, wherein the thermal initiator is included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the acrylic resin. The pressure-sensitive adhesive composition of claim 1, further comprising a multifunctional acrylate and a radical polymerization initiator. The pressure-sensitive adhesive composition of claim 7, wherein the multifunctional acrylate comprises a ring structure or a urethane bond in the molecular structure. The pressure-sensitive adhesive composition of claim 7, wherein the multifunctional acrylate is included in an amount of 1 to 50 parts by weight based on 100 parts by weight of the acrylic resin. 8. The radical polymerization initiator according to claim 7, wherein the radical polymerization initiator is benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone , 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexyl Phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2- Propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2- Aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p- Dimethylamino benzoic acid Stear, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide At least one pressure-sensitive adhesive composition selected. The pressure-sensitive adhesive composition of claim 7, wherein the radical polymerization initiator is included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the acrylic resin. The pressure-sensitive adhesive composition of claim 1, further comprising an antistatic agent. materials; And a pressure-sensitive adhesive layer formed on one or both surfaces of the substrate and comprising a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 12. The protective material for an optical member according to claim 13, wherein the substrate comprises a polyester film, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a vinyl chloride copolymer film or a polyimide film. film. The protective film for an optical member according to claim 13, wherein the pressure-sensitive adhesive layer has a gel content of 90% to 99% represented by the following general formula (1): [Formula 1] Gel content = B / A × 100 In the general formula 1, A represents the mass of the pressure-sensitive adhesive, B represents the dry mass of the insoluble content of the pressure-sensitive adhesive after immersing the pressure-sensitive adhesive for 48 hours at room temperature with ethyl acetate. A first step of applying a coating liquid containing the pressure-sensitive adhesive composition according to any one of claims 1 to 12 on the process substrate; A second step of drying the coating solution applied in the first step; And a third step of irradiating light to the coating liquid dried in the second step. The method of claim 16, wherein the second step is performed at a temperature of 100 ° C. to 150 ° C. 18. The method of claim 16, wherein the second step is performed for 1 to 5 minutes. A polarizer having a protective film according to claim 13 attached to one side or both sides. 20. A liquid crystal display device comprising a liquid crystal panel having a polarizing plate according to claim 19 attached to one or both surfaces thereof.