KR101992002B1 - Adhesive film for polarizing plate, polarizing plate comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

Wherein the modulus difference of the formula (1) is from 0.1 MPa to 0.3 MPa, and the creep difference of the formula (2) is from 200 A polarizing plate including the same, and an optical display device including the polarizing plate.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive film for a polarizing plate, a polarizing plate including the same, and an optical display device including the polarizing plate.

The present invention relates to a pressure-sensitive adhesive film for a polarizing plate, a polarizing plate including the same, and an optical display device including the same.

The liquid crystal display device includes a liquid crystal panel and a polarizing plate attached to both sides of the liquid crystal panel. The polarizing plate includes a polarizer and a protective film formed on one or both surfaces of the polarizer to protect the polarizer. The polarizing plate is attached to the liquid crystal panel by an adhesive film for a polarizing plate.

Vehicle displays directly affected by direct sunlight are required to have high durability even at high temperatures of 90 ° C or higher because a high voltage is applied to increase the brightness of BLU as well as to the external environment. The liquid crystal panel of the liquid crystal display device may be warped by the stress of the polarizing plate at a high temperature. Particularly, the panel warpage may deteriorate the screen quality of the liquid crystal display device. If the modulus of the pressure-sensitive adhesive is lowered to improve warpage, the durability of the heat-resistant or anti-wet heat is lowered. In order to increase the durability, a method of using an adhesive resin having a high molecular weight or high degree of crosslinking is generally used, but the panel warpage is lowered inversely. Durability and panel warpage are in trade-off relationship with each other, and a pressure-sensitive adhesive is needed to simultaneously improve it.

The background art of the present invention is disclosed in Japanese Patent No. 5738967.

An object of the present invention is to provide a pressure-sensitive adhesive film for a polarizing plate having improved panel warpage and high durability.

Another object of the present invention is to provide a pressure-sensitive adhesive film for a polarizing plate having a high durability effect in which a difference between a modulus and a creep between a normal temperature and a high temperature is within a specific range, thereby improving panel warping and maintaining reliability even at a high temperature of 90 ° C or higher.

The pressure sensitive adhesive film for a polarizing plate of the present invention is formed from a pressure sensitive adhesive composition for a polarizing plate comprising a (meth) acrylic copolymer, a first isocyanate curing agent, and a second isocyanate curing agent, Is in the range of 0.1 MPa to 0.3 MPa, and the creep difference in the following formula (2) is in the range of 200 to 500 mu m.

<Formula 1>

Modulus difference = modulus 1 - modulus 2

(In the above formula 1, the modulus 2 and the modulus 1 are as defined in the detailed description of the present invention)

<Formula 2>

Creep Difference = Creep 2 - Creep 1

(In the above formula 2, creep 2 and creep 1 are as defined in the detailed description of the present invention).

The polarizing plate of the present invention may include the pressure-sensitive adhesive film for a polarizing plate of the present invention or the pressure-sensitive adhesive film formed of the pressure-sensitive adhesive composition for a polarizing plate of the present invention.

The optical display device of the present invention may include the polarizing plate or the polarizing plate.

The present invention provides a pressure-sensitive adhesive film for a polarizing plate having improved panel warping and high durability.

The present invention provides a pressure-sensitive adhesive film for a polarizing plate having a high durability effect that maintains reliability even at a temperature of 90 ° C or higher while improving panel warpage due to a specific range of difference between modulus and creep between room temperature and high temperature.

1 is a conceptual diagram of measurement of a creep in this specification.
2 is a cross-sectional view of a polarizing plate of one embodiment of the present invention.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

It should be noted that the terms "upper" and "lower" in the present specification are based on the drawings and are not necessarily fixed to the upper and lower portions, . In the present specification, "adhesive film for polarizing plate" and "pressure-sensitive adhesive composition for polarizing plate" may be referred to as "adhesive film" and "pressure-sensitive adhesive composition", respectively. As used herein, "(meth) acrylic" means acrylic and / or methacrylic.

1, a polarizing plate 23 with an adhesive film is laminated on the end of a soda-lime-free alkali glass plate 20 with an area of axb (for example, 15 mm x 15 mm), and a load W of 1000 The polarized plate 23 with the adhesive film was pulled from the soda lime-free alkali glass plate 20 when the polarizing plate 23 with the adhesive film was pulled for 20 seconds. The polarizing plate 23 with an adhesive film includes a polarizing plate 22 formed on the adhesive film 21. The polarizing plate 22 includes a triacetylcellulose film, a polarizer, and a triacetylcellulose film which are sequentially laminated. The creep at 25 占 폚 is the measurement of the pushing distance of the adhesive film of the polarizing plate 23 from the soda lime-free alkali glass plate 20 when pulled for 25 seconds at a constant force W of 2250 gf for 1000 seconds. The creep at 95 deg. C was the measurement of the pushing distance of the adhesive film of the polarizing plate 23 from the soda lime-free alkali glass plate 20 when pulled for 1000 seconds at a constant force W of 1500 gf at 95 deg. The creep can be measured using TEXTURE ANALYZER TA.XT PLUS (5 kg load cell, EKO Instruments). The adhesive film can be prepared by applying the pressure-sensitive adhesive composition to a release film (PET film), drying at 90 DEG C for 4 minutes, and aging at 35 DEG C and 45% relative humidity for 96 hours. The thickness of the adhesive film may be 10 占 퐉 to 40 占 퐉.

As used herein, "modulus" is a storage modulus.

As used herein, the term "solids" refers to the entirety of the pressure-sensitive adhesive composition excluding the solvent.

In the present specification, the "glass transition temperature" of a monomer may mean a glass transition temperature measured by DS Instrument's DSC Discovery for a homopolymer of a monomer to be measured. Specifically, the homopolymer of the monomer to be measured was heated to 180 ° C at a rate of 20 ° C / minute, cooled to - 120 ° C at the same rate, and then heated to 300 ° C at a rate of 10 ° C / minute , The inflection point of the endothermic transition curve can be determined as the glass transition temperature.

Hereinafter, an adhesive film for a polarizing plate according to an embodiment of the present invention will be described.

The pressure-sensitive adhesive film for a polarizing plate according to this embodiment may have a modulus difference of 0.1 to 0.3 MPa in the following formula 1 and a creep difference of 200 to 500 μm in the following formula 2:

<Formula 1>

Modulus difference = modulus 1 - modulus 2

(In the above formula 1, the modulus 1 is the modulus (unit: MPa) at 25 ° C of the pressure-sensitive adhesive film for a polarizing plate,

The modulus 2 is a modulus (unit: MPa) at 95 ° C of the polarizing plate adhesive film,

<Formula 2>

Creep Difference = Creep 2 - Creep 1

(In the formula 2, the creep 1 is a creep (unit: 탆) at 25 캜 of the polarizing plate adhesive film,

The creep 2 is a creep (unit: 탆) at 95 캜 of the polarizing plate adhesive film.

The pressure-sensitive adhesive film for a polarizing plate can improve the panel warpage at a high temperature and enhance the heat resistance and moisture proof resistance by securing the modulus difference of the formula (1) and the creep difference of the formula (2). Specifically, the modulus difference in the formula (1) may be 0.1 MPa to 0.2 MPa, and the creep difference in the formula (2) may be 200 to 400 μm. Within this range, there may be more bending effects as well as improved panel warping, reliability improvement even in harsher conditions.

The pressure-sensitive adhesive film for a polarizing plate may have a modulus of 0.001 MPa or more, specifically 0.004 MPa or more and 0.1 MPa or less at 95 占 폚, and a creep at 95 占 폚 may be 400 占 퐉 or more and 400 占 퐉 or more and 800 占 퐉 or less. Within this range, panel warpage can be improved and durability can be maintained.

The pressure-sensitive adhesive film for a polarizing plate may have a modulus of 0.1 MPa or more, specifically 0.1 MPa or more and 0.4 MPa or less at 25 占 폚, and a creep at 25 占 폚 may be 100 占 퐉 or more and specifically 100 占 퐉 or more and 500 占 퐉 or less. In the above range, reliability is good even at a high temperature, and a warp effect can be obtained.

The pressure-sensitive adhesive film for a polarizing plate may have a modulus at 95 ° C of modulus at 25 ° C of 1:10 to 1:30, specifically 1:20 to 1:30. Within the above range, there is an effect of improving the panel warpage and reliability, and the effect of increasing the adhesion of the substrate.

The adhesive film for a polarizing plate is optically transparent and can be used in an optical display device. Specifically, the adhesive film may have a light transmittance of 85% or more, more specifically 85% to 99.9% in a visible light region, for example, a wavelength of 380 nm to 780 nm.

The thickness of the pressure sensitive adhesive film for a polarizing plate may be 40 占 퐉 or less, specifically 5 占 퐉 to 30 占 퐉. In the above range, it can be used in an optical display device.

The pressure sensitive adhesive film for a polarizing plate may be formed of a pressure sensitive adhesive composition for a polarizing plate comprising a (meth) acrylic copolymer, a first isocyanate curing agent, and a second isocyanate curing agent. The pressure-sensitive adhesive composition for a polarizing plate may contain a first isocyanate-based curing agent and a second isocyanate-based curing agent in a specified amount to provide a difference between the modulus difference of the formula 1 and the creep difference of the formula 2 to improve panel warpage and durability simultaneously, So that the peel strength can be secured. The second isocyanate-based curing agent can significantly reduce the modulus of the adhesive film for a polarizing plate at 95 ° C compared to 25 ° C, thereby improving the panel warpage and ensuring the peeling strength to which the adhesive film can be applied even at high temperatures. The first isocyanate-based curing agent and the second isocyanate-based curing agent all have a semi-IPN (interpenetrating polymer network) structure, thereby increasing the crosslinking density even at 95 ° C, thereby improving durability and improving warpage.

The pressure-sensitive adhesive film for a polarizing plate may be prepared by coating a pressure-sensitive adhesive composition for a polarizing plate to a predetermined thickness, drying (solvent volatilization), and then cutting. As described above, the pressure-sensitive adhesive composition for a polarizing plate can be sufficiently aged immediately after coating and drying, so that the processability of the pressure-sensitive adhesive film can be improved and the cutting property can be improved.

Hereinafter, the pressure-sensitive adhesive composition for a polarizing plate will be described in detail.

(Meth) acrylic copolymer can form a matrix of a pressure-sensitive adhesive film for a polarizing plate. The (meth) acrylic copolymer may be a (meth) acrylic copolymer having a hydroxyl group, a carboxylic acid group and an alkyl group. (Meth) acrylic copolymer may be a copolymer of a monomer mixture comprising a (meth) acrylic monomer having a hydroxyl group, a (meth) acrylic monomer having a carboxylic acid group, and a (meth) acrylic monomer having an alkyl group, have.

The (meth) acrylic monomer having a hydroxyl group may react with the first isocyanate-based curing agent and the second isocyanate-based curing agent to achieve peel strength. The (meth) acrylic monomer having a hydroxyl group is a (meth) acrylic monomer having a C1 to C20 alkyl group having at least one hydroxyl group, a (meth) acrylic monomer having a C3 to C20 cycloalkyl group having at least one hydroxyl group, (Meth) acryl-based monomers having C6 to C20 aromatic groups. Specifically, the (meth) acrylic monomer having a hydroxyl group is preferably selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, At least one of mono (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclopentyl (meth) acrylate and 4-hydroxycyclohexyl (meth) . These may be included singly or in combination of two or more. The (meth) acrylic monomer having a hydroxyl group may be contained in the monomer mixture in an amount of 0.1 wt% to 5 wt%, specifically 0.5 wt% to 5 wt%. In the above range, the durability is improved by the reaction with the curing agent which reacts with the hydroxyl group, and lifting and peeling may not occur.

The (meth) acrylic monomer having a carboxylic acid group may include (meth) acrylic acid and the like. The (meth) acrylic monomer having a carboxylic acid group may be contained in the monomer mixture in an amount of 0.1% by weight to 15% by weight, specifically 0.1% by weight to 5% by weight. Within the above range, the reaction with the curing agent which reacts with the carboxylic acid group may shorten the aging time and improve the durability, so that the peeling and peeling may not occur.

The (meth) acrylic monomer having an alkyl group includes a mixture of (meth) acrylic monomers having an alkyl group having a different glass transition temperature of the homopolymer, thereby achieving Tg control and hardness improvement of the polarizing plate adhesive film. Wherein the mixture is a mixture of a (meth) acrylic monomer having a first alkyl group and a (meth) acrylic monomer having a second alkyl group, and the (meth) acrylic monomer having a first alkyl group is a mixture of The glass transition temperature of the homopolymer may be low. Here, the (meth) acrylic monomer having the first alkyl group may be contained in an excessive amount relative to the (meth) acrylic monomer having the second alkyl group. Specifically, from 55 parts by weight to 95 parts by weight, specifically from 60 parts by weight to 80 parts by weight of the (meth) acrylic monomer having the first alkyl group in the 100 parts by weight of the mixture, and from 5 parts by weight To 45 parts by weight, specifically 20 parts by weight to 40 parts by weight. Within this range, there may be an effect of controlling hardness and tackiness according to the synergistic effect of the glass transition temperature (Tg).

The (meth) acrylic monomer having the first alkyl group may be at least one selected from the group consisting of ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl acrylate, isobutyl (meth) acrylate, pentyl (Meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, Acrylate, and dodecyl (meth) acrylate. Preferably, n-butyl acrylate can be used.

In one embodiment, the (meth) acrylic monomer having the first alkyl group may have a glass transition temperature of the homopolymer of 0 占 폚 or less, specifically, -10 占 폚 to -100 占 폚. Within this range, there may be an effect of controlling hardness and tackiness according to the synergistic effect of the glass transition temperature (Tg).

The (meth) acrylic monomer having the second alkyl group may include at least one of methyl (meth) acrylate, iso-propyl (meth) acrylate, and t-butyl (meth) acrylate. These may be included singly or in combination of two or more.

In one embodiment, the (meth) acrylic monomer having a second alkyl group can be a (meth) acrylic monomer having a glass transition temperature of the homopolymer of 5 ° C or higher, specifically 5 ° C to 150 ° C, 5 ° C to 100 ° C . Within this range, there may be an effect of controlling hardness and tackiness according to the synergistic effect of the glass transition temperature (Tg).

The (meth) acrylic monomer having an alkyl group may be contained in the monomer mixture in an amount of 80% by weight to 99% by weight, specifically 90% by weight to 99% by weight. Within the above range, the haze of the pressure-sensitive adhesive layer is lowered, and the effect of stabilizing the port life can be obtained.

The (meth) acrylic copolymer may be prepared by polymerizing a monomer mixture by a conventional polymerization method. The polymerization method may include conventional methods known to those skilled in the art. For example, the (meth) acrylic copolymer can be prepared by adding an initiator to a monomer mixture, followed by conventional copolymerization, such as suspension polymerization, emulsion polymerization, solution polymerization and the like. The polymerization temperature may be 50 占 폚 to 70 占 폚, and the polymerization time may be 6 hours to 10 hours. The initiator may be an azo-based polymerization initiator; And / or peroxides such as benzoyl peroxide or acetyl peroxide, and the like.

(Meth) acrylic copolymer may have a weight average molecular weight (Mw) of 2,000,000 or less, specifically 800,000 to 1,200,000. Within this range, durability can be increased and high-speed coating of the pressure-sensitive adhesive composition can be made possible. The weight average molecular weight may be a value obtained by converting the polystyrene in the gel permeation chromatography method. (Meth) acrylic copolymer may have a glass transition temperature of -60 캜 to 0 캜, specifically, -45 캜 to -5 캜. Within the above range, it has fluidity as a pressure-sensitive adhesive and high durability can be ensured. The (meth) acrylic copolymer may have a polydispersity of 2.5 to 9.0, specifically 3 to 6. Within the above range, the polymerization is stable and the decrease in durability can be excluded. The (meth) acrylic copolymer may have an acid value of 5 mg KOH / g or less, more specifically 0.01 mg KOH / g to 3 mg KOH / g. Within this range, it is possible to realize a corrosion inhibiting effect directly or indirectly on the adherend.

The curing agent may comprise a mixture of a first isocyanate curing agent and a second isocyanate curing agent. The first isocyanate-based curing agent and the second isocyanate-based curing agent are different from each other. The adhesive film containing only the first isocyanate curing agent had a modulus of the adhesive film at 25 占 폚 and 95 占 폚 at a high level and the effect of improving the panel warpage was weak. The adhesive film containing only the second isocyanate-based curing agent had only a slight improvement in reliability. The first isocyanate-based curing agent: the second isocyanate-based curing agent may be contained in a weight ratio of 1.5: 1 to 10: 1, specifically, a weight ratio of 1.5: 1 to 6: 1. In the above range, the modulus difference of the formula (1) and the creep difference of the formula (2) can be satisfied at the same time, whereby the panel warpage improvement and the endurance reliability improvement can be obtained.

The first isocyanate-based curing agent does not contain a linear alkylene group having 10 to 20 carbon atoms. On the other hand, the second isocyanate-based curing agent includes a linear alkylene group having 10 to 20 carbon atoms.

The first isocyanate-based curing agent can react with the hydroxyl group of the (meth) acrylic copolymer to cure the pressure-sensitive adhesive composition, thereby securing the peel strength and increasing the modulus. The first isocyanate-based curing agent may include an isocyanate-based curing agent having three or more functional groups, specifically, three to six functional groups. Specifically, a trifunctional isocyanate curing agent including trifunctional trimethylolpropane-modified toluene diisocyanate adduct, trifunctional toluene diisocyanate trimer, trimethylolpropane-modified xylene diisocyanate adduct, etc., 6-functional trimethylolpropane Modified toluene diisocyanate, modified tolylene diisocyanate, hexafunctional isocyanurate-modified toluene diisocyanate, tolylene diisocyanate, chlorophenylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate Or an isocyanate compound to which the isocyanate monomer is added with trimethylolpropane or the like; And isocyanurate or isocyanate biuret type isocyanate and urethane prepolymer type isocyanate reacted with polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol and the like; &Lt; / RTI &gt; These may be included singly or in combination of two or more. Preferably, the first isocyanate-based curing agent may be a trifunctional isocyanate-based curing agent.

In one embodiment, the first isocyanate-based curing agent is an aromatic-based curing agent having an aromatic group, and the second isocyanate-based curing agent may be a non-aromatic-based curing agent having no aromatic group.

The first isocyanate curing agent is used in an amount of 10 parts by weight or less, specifically 0.001 part by weight to 10 parts by weight, more specifically 0.01 part by weight to 10 parts by weight, and 0.01 part by weight to 5 parts by weight, based on 100 parts by weight of the (meth) , 1.3 parts by weight to 5 parts by weight, and 1.3 parts by weight to 4 parts by weight. Within the above range, there may be an effect of increasing durability (heat resistance) and peeling force.

The second isocyanate-based curing agent reacts with the hydroxyl group of the (meth) acrylic copolymer to cure the pressure-sensitive adhesive composition to secure the peel strength, and by lowering the modulus of the pressure-sensitive adhesive film at 95 ° C, flexibility is imparted to the pressure- Can be improved. The second isocyanate-based curing agent may include one or more moieties of the following formula (1): &lt; EMI ID =

&Lt; Formula 1 >

- (CH ₂ ) _n --O - C (═O) -NH - (CH ₂ ) _m --NCO

(Wherein n is an integer of 10 to 20, m is an integer of 1 to 20, and * is a linking site).

In the above formula (1), the NCO group can be cured with a (meth) acrylic copolymer. In the above formula (1), - (CH 2) _n - is a flexible unit, which imparts flexibility to the adhesive film to improve bending of the parchment.

The second isocyanate-based curing agent contains an alkylene group having 10 to 20 carbon atoms and can impart flexibility to the pressure-sensitive adhesive film by lowering the modulus of the pressure-sensitive adhesive film at 95 ° C. The second isocyanate-based curing agent may include, but is not limited to, DURANATE, Urethane adduct of Asahi KASEI or Biuret, E402-80B, E402-100, TSE-100, AE700-100 and the like.

The second isocyanate-based curing agent is used in an amount of 5 parts by weight or less, specifically 0.001 part by weight to 5 parts by weight, more specifically 0.01 part by weight to 5 parts by weight, and 0.4 part by weight to 5 parts by weight, based on 100 parts by weight of the (meth) , And 0.4 parts by weight to 3 parts by weight. Within this range, there may be an effect of improving panel warpage and increasing cross-linking density.

The total amount of the first isocyanate curing agent and the second isocyanate curing agent is 20 parts by weight or less, specifically 0.01 part by weight to 15 parts by weight, more specifically 1 part by weight to 15 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer . Within the above range, the durability and the panel warping are improved, and the peeling strength can be secured.

The pressure-sensitive adhesive composition for a polarizing plate may further comprise a silane coupling agent. The silane coupling agent can increase the adhesion of the polarizing plate adhesive film to an adherend such as glass. The silane coupling agent may comprise conventional silane coupling agents known to those skilled in the art. For example, the silane coupling agent may have an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. ; A polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and (meth) acryloxypropyltrimethoxysilane; Containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane. ; mercapto group-containing silicon compounds such as? -mercaptopropyltrimethoxysilane,? -mercaptopropyltriethoxysilane,? -mercaptobutyltrimethoxysilane,? -mercaptopropylmethyldimethoxysilane, and the like But are not limited to, at least one member selected from the group consisting of the following groups.

The silane coupling agent may be contained in an amount of 0.01 to 5 parts by weight, specifically 0.01 to 2 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer. Within the above range, the durability is excellent, the lifting phenomenon is particularly good under the moisture-proof reliability condition, and the physical property change over time such as glass peeling force and the like can be small. Particularly, the above effect can be further improved by including an epoxy group or a mercapto group-containing silane coupling agent.

The pressure sensitive adhesive composition for a polarizing plate may further include at least one of a tackifier resin and an antistatic agent. The tackifying resin enhances the tackiness of the tacky film, and may include tackifying resins usually known to those skilled in the art. The antistatic agent suppresses the generation of static electricity when the adhesive film is removed from the adherend, and may include a quaternary ammonium antistatic agent. One or more of the tackifier resin and the antistatic agent may be contained in an amount of 0.1 to 2 parts by weight, specifically 0.1 to 1 part by weight, based on 100 parts by weight of the (meth) acrylic copolymer. Within the above range, the effect can be realized without affecting the physical properties of the pressure-sensitive adhesive film.

The pressure-sensitive adhesive composition for a polarizing plate may further contain usual additives. The additives may include ultraviolet absorbers, antioxidants, tackifying resins, plasticizers, reworkers, and the like. The additives may comprise conventional species known to those skilled in the art. The additive may be included in an amount of 0.001 to 5 parts by weight, specifically 0.01 to 1 part by weight based on 100 parts by weight of the (meth) acrylic copolymer. Within the above range, the additive effect can be obtained without affecting the physical properties of the polarizing plate adhesive film.

The pressure-sensitive adhesive composition for a polarizing plate may further include a solvent such as methyl ethyl ketone to improve the applicability of the composition.

The pressure-sensitive adhesive composition for a polarizing plate may have a viscosity of 1,000 cPs to 4,000 cPs at 25 占 폚. Within the above range, the thickness of the adhesive film can be easily adjusted, there is no unevenness on the adhesive film, the coated surface is uniform, and it is suitable for high-speed coating.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described.

The polarizing plate of the present invention may include a pressure-sensitive adhesive film for a polarizing plate according to embodiments of the present invention. The polarizing plate of the present invention can be manufactured by adhering a pressure sensitive adhesive film for a polarizing plate according to embodiments of the present invention to one side of a polarizing plate or by coating the pressure sensitive adhesive composition for a polarizing plate on a side of a polarizing plate to a predetermined thickness and then aging.

The polarizing plate may include a polarizer and an optical film formed on at least one side of the polarizer. The polarizer and the optical film are based on conventional contents known to those skilled in the art.

The thickness of the polarizing plate may be 30 탆 to 250 탆, specifically 140 탆 to 200 탆. In the above range, it can be used in an optical display device.

2 is a cross-sectional view of a polarizing plate of one embodiment of the present invention. 2, the polarizer 100 of the present invention includes a polarizer 110, a first optical film 120 formed on the upper surface of the polarizer 110, an adhesive film (not shown) formed on the lower surface of the polarizer 110 130, and the adhesive film 130 may include the adhesive film for a polarizing plate of the present invention. Although not shown in Fig. 2, the adhesive film 130 may be adhered to the liquid crystal display panel.

The polarizer 110 is made of a polyvinyl alcohol-based film and is not particularly limited as long as it is a polyvinyl alcohol-based film regardless of the manufacturing method. For example, a polarizer may be a modified polyvinyl alcohol film such as a partially-formalized polyvinyl alcohol film or an acetoacetyl-modified polyvinyl alcohol film. Specifically, a polyvinyl alcohol film is prepared by dyeing iodine or a dichroic dye and stretching it in a predetermined direction. Specifically, it is produced through a swelling process, a dyeing process, and a stretching process. Methods of performing each step are commonly known to those skilled in the art. The polarizer 110 may have a thickness of 5 占 퐉 to 50 占 퐉. And can be used in an optical display device in the above range. The first optical film 120 may be formed of a material selected from the group consisting of a ring-shaped polyolefin based material including an optically transparent resin, specifically, a cyclic olefin polymer (COP), a poly (meth) acrylate based, a polycarbonate based, a polyethylene terephthalate Based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, poly (ethylene terephthalate), and poly A polyvinyl chloride-based resin, a polyvinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin. The first optical film 120 may have a thickness of 10 占 퐉 to 200 占 퐉, for example, 20 占 퐉 to 120 占 퐉, and may be used in an optical display device in the above range.

Although not shown in FIG. 2, an adhesive layer formed of an adhesive for a polarizing plate may be included between the polarizer and the first optical film, and the polarizing plate adhesive may include an aqueous adhesive, a pressure sensitive adhesive, and an ultraviolet curable adhesive. 2 shows a polarizing plate in which an adhesive film 130, a polarizer 110 and a first optical film 120 are sequentially formed. The polarizing plate 130 includes a second optical film, a polarizer 110, (120) may be included in the scope of the present invention. The second optical film may be formed of the same or different resin as the first optical film 120. The thickness of the second optical film may be the same as or different from that of the first optical film 120.

The optical display device of one embodiment of the present invention may include the polarizing plate of the present invention. For example, the optical display device may include a liquid crystal display device, an organic light emitting display device, but is not limited thereto. The liquid crystal display device of one embodiment of the present invention includes a liquid crystal display panel, a first polarizer plate formed on the upper surface of the liquid crystal display panel, a second polarizer plate formed on the lower surface of the liquid crystal display panel, and a backlight unit formed below the second polarizer plate, At least one of the first polarizing plate and the second polarizing plate may include the polarizing plate of the embodiment of the present invention.

The liquid crystal display panel may employ a twisted nematic (TN) mode, a VA (vertical alignment) mode, a PVA (patterned vertical alignment) mode, an IPS mode or an S-PVA (super-patterned vertical alignment) mode. Particularly, the liquid crystal display panel of the TN mode can have excellent light leakage improving effect.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The specifications of the components used in the following examples and comparative examples are as follows

(A) (Meth) Acrylic Copolymer: A (meth) acrylic copolymer

(B) an isocyanate-based curing agent

(B1) First isocyanate curing agent: Coronate L (Japanese polyurethane, solid content 75%)

(B2) Second isocyanate-based curing agent: Duranate (Asahi KASEI, AE700-100 100% solids)

(C) Silane coupling agent: KBM403 (ShinYeatsu, solid content: 100% by weight)

Manufacturing example

63 parts by weight of n-butyl acrylate (BA), 34 parts by weight of methyl acrylate (MA), 2 parts by weight of 2-hydroxyethyl methacrylate (2 parts by weight) were added to a 1 L reactor equipped with a cooling device, -HEMA), 2 parts by weight of acrylic acid (AA), and 100 parts by weight of ethyl acetate (EA) as a solvent. Then, nitrogen gas was introduced for 1 hour to remove oxygen to replace the reactor, and the temperature was maintained at 62 ° C. After the homogeneous stirring of the monomer mixture, 0.07 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and the mixture was reacted for 8 hours to obtain a (meth) acrylic copolymer (weight average molecular weight: 80,000 to 1,100,000, : 4.0, glass transition temperature: -31 占 폚).

Example  One

To 20 parts by weight of methyl ethyl ketone were added 100 parts by weight of the acrylic copolymer of Production Example, 2.50 parts by weight (based on solid content) of the first isocyanate curing agent, and 0.67 parts by weight (based on the solid content) of the second isocyanate curing agent, and the mixture was stirred for 3 minutes. 0.03 part by weight (based on solid content) of a silane coupling agent was further added and stirred for 20 minutes to give a pressure-sensitive adhesive composition for a polarizing plate.

The resulting pressure-sensitive adhesive composition for a polarizing plate was applied to a release film, dried to prepare a pressure-sensitive adhesive layer having a thickness of 26 탆, laminated on a polarizing plate and aged at 35 캜 and 45% relative humidity for 48 hours, To prepare a polarizing plate. At this time, the polarizing plate was produced by sequentially laminating a triacetyl cellulose film (thickness: 40 탆), a polarizer (thickness: 5 탆), and a triacetyl cellulose film (thickness: 40 탆).

Example  2

A polarizing plate with a polarizing plate adhesive film was produced in the same manner as in Example 1, except that the contents of the first isocyanate curing agent and the second isocyanate curing agent were changed to the following Table 1 (unit: parts by weight) Respectively.

Comparative Example  1 to Comparative Example  4

A polarizing plate with a pressure-sensitive adhesive film for a polarizing plate was prepared in the same manner as in Example 1, except that the contents of the first isocyanate curing agent and the second isocyanate curing agent were changed as shown in Table 1 below.

The properties of the polarizers prepared in Examples and Comparative Examples were evaluated in the following Table 1, and the results are shown in Table 1 below.

(1) Modulus: The polarizing plate for polarizing plate produced in Examples and Comparative Examples was separated. A plurality of the obtained pressure sensitive adhesive films for polarizing plates were laminated and cut to prepare circular specimens having a thickness of 500 탆 and a diameter of 8 mm. The specimens thus prepared were irradiated with a Physica MCR501 (Anton parr) on a disk having a diameter of 8 mm at 0 캜 to 100 캜 At 25 DEG C and 95 DEG C when the temperature was measured at 1 Hz and 5% strain while raising the temperature at a heating rate of 5 DEG C / min.

The modulus difference was calculated according to Equation (1).

(2) Creep: Creep 1 was measured using a tensile test instrument TEXTURE ANALYZER TA.XT PLUS (load cell 5 kg, EKO Instruments) with reference to FIG.

The polarizing plate 23 with the polarizing plate for polarizing plate of Examples and Comparative Examples was cut into a rectangle having a size of width x length (15 mm x 120 mm). The polarizing plate 23 was laminated to the end of a soda lime-free alkali glass plate 20 in an area of axb (for example, 15 mm x 15 mm), adhered at 50 ° C and 3.5 atm, left at 25 ° C for 1 day, Specimens were prepared. When the specimen prepared in the above tensile test measuring instrument was fixed and the polarizer was pulled at 25 DEG C for 1000 seconds with a constant force W of 2250 gf, the pushing distance of the pressure sensitive adhesive film of the polarizer 23 from the soda lime non- Were measured.

In addition, the polarizing plate 23 with the polarizing plate for polarizing plate of Examples and Comparative Examples was cut into a rectangle having a size of width x length (15 mm x 80 mm). The polarizing plate 23 was laminated to the end of a soda lime-free alkali glass plate 20 in an area of axb (for example, 15 mm x 15 mm), adhered at 50 ° C and 3.5 atm, left at 25 ° C for 1 day, Specimens were prepared. An oven was additionally provided in the tensile test measuring instrument, and the inside of the tensile test measuring instrument was maintained at 95 DEG C, and the prepared specimen was fixed to the tensile test measuring instrument. The polarizing plate was heated at a constant force W of 1500 gf for 1000 seconds The pushing distance of the adhesive film of the polarizing plate 23 from the soda lime-free alkali glass plate 20 was measured.

The creep difference was calculated according to Equation 2 above.

(3) Panel warpage: A polarizing plate (width x length, 180 mm x 110 mm, rectangular) having the adhesive films of Examples and Comparative Examples was attached to a liquid crystal cell (width x length, 190 mm x 120 mm, rectangle) via an adhesive film Specimens were prepared. The prepared specimens were placed in an oven at 95 ° C. and taken out for 24 hours, 120 hours, 250 hours, 500 hours, and 1000 hours, and the panel warpage was measured. The specimens were placed on a flat surface, weights were placed above one edge, and the distance between the flat surface and the panel was measured at diagonal corners. ? Indicates that the distance between the flat portion and the panel is not less than 0 mm and not more than 2 mm;? Indicates that the distance is more than 2 mm and not more than 5 mm;

(4) Endurance reliability: A polarizing plate (width x length, 100 mm x 80 mm) having the pressure-sensitive adhesive films of Examples and Comparative Examples was attached to a glass plate through an adhesive film and closely contacted at 50 ° C and 3.5 atm. The test piece was allowed to stand at 95 DEG C for 1000 hours to evaluate the heat resistance reliability. The specimens were allowed to stand at 60 DEG C and 90% RH for 500 hours and then left at room temperature for 1 hour, and then their moisture heat resistance was evaluated. When the specimen was observed with naked eyes, it was evaluated as? When there was no bubble or end exfoliation between the pressure-sensitive adhesive film or the pressure-sensitive adhesive film and?, When the bubble or end exfoliation was somewhat?, And when there were many bubbles or end extrusion.

Example Comparative Example One 2 One 2 3 4 (A) (parts by weight) 100 100 100 100 100 100 (B1) (parts by weight) 2.50 1.87 1.25 - 3.62 3.00 (B2) (parts by weight) 0.67 1.07 1.43 2.16 - 0.37 (C) (parts by weight) 0.03 0.03 0.03 0.03 0.03 0.03 Modulus
(MPa, @ 25 C) 0.13 0.12 0.10 0.08 0.70 0.49 Modulus
(MPa, @ 95 &lt; 0 &gt; C) 0.005 0.0045 0.003 0.0015 0.550 0.075 The modulus difference (MPa) 0.125 0.1155 0.097 0.0785 0.150 0.415 Creep (占 퐉, @ 25 占 폚) 113 124 155 237 58 97 Creep (탆, @ 95 ° C) 412 486 593 885 80 284 Creep Difference in Equation 2
(탆) 299 362 438 648 22 187 Panel warp ○ ○ ○ ○ x x Heat Resistance Reliability ○ ○ △ x ○ ○ Moisture proof reliability ○ ○ △ x ○ ○

As shown in Table 1, the polarizing plate adhesive film of the present invention can improve the panel warpage and improve the heat resistance and the moisture and heat resistance.

On the other hand, in Comparative Example 3 containing only the first isocyanate curing agent, the modulus of the adhesive film was high at 25 캜 and 95 캜, and the effect of improving the panel warpage was weak. Comparative Example 2 including only the second isocyanate-based curing agent showed only a slight improvement in reliability. Comparative Example 1 and Comparative Example 4 in which the modulus difference in Formula 1 and the creep difference in Formula 2 were outside the range of the present invention were poor in reliability or panel warpage even if both the first and second isocyanate curing agents were included .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (13)

(Meth) acrylic copolymer, a first isocyanate curing agent, and a second isocyanate curing agent, wherein the pressure-sensitive adhesive composition for a polarizing plate is a pressure-
Wherein the pressure-sensitive adhesive film for a polarizing plate has a modulus difference of 0.1 to 0.3 MPa of the following formula 1 and a creep difference of 200 to 500 μm of the following formula 2:
<Formula 1>
Modulus difference = modulus 1 - modulus 2
(In the above formula 1, the modulus 1 is the modulus (unit: MPa) at 25 ° C of the pressure-sensitive adhesive film for a polarizing plate,
The modulus 2 is a modulus (unit: MPa) at 95 DEG C of the polarizing plate adhesive film,
<Formula 2>
Creep Difference = Creep 2 - Creep 1
(In the formula 2, the creep 1 is a creep (unit: 탆) at 25 캜 of the polarizing plate adhesive film,
The creep 2 is a creep (unit: 탆) at 95 캜 of the polarizing plate adhesive film.
The pressure sensitive adhesive film for a polarizing plate according to claim 1, wherein the pressure sensitive adhesive film for a polarizing plate has a modulus of 0.004 MPa or more and 0.1 MPa or less at 95 캜.
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the adhesive film for a polarizing plate has a creep at 400 占 퐉 to 800 占 퐉 at 95 占 폚.
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the pressure-sensitive adhesive film for a polarizing plate has a modulus at 95 ° C of modulus: 25 ° C of 1:10 to 1:30.
The adhesive film for a polarizing plate according to claim 1, wherein the first isocyanate curing agent and the second isocyanate curing agent form a semi-IPN (interpenetrating polymer network) structure in the polarizing plate adhesive film.
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the first isocyanate-based curing agent has an aromatic group and comprises an isocyanate-based curing agent having three to six functional groups.
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the second isocyanate-based curing agent comprises a moiety of the following formula (1):
&Lt; Formula 1 >
- (CH ₂ ) _n --O - C (═O) -NH - (CH ₂ ) _m --NCO
(Wherein n is an integer of 10 to 20, m is an integer of 1 to 20, and * is a linking site).
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the first isocyanate-based curing agent: the second isocyanate-based curing agent is contained in the pressure-sensitive adhesive composition for a polarizing plate in a weight ratio of 1.5: 1 to 10: 1.
The copolymer according to claim 1, wherein the (meth) acrylic copolymer is a copolymer of a monomer mixture comprising a (meth) acrylic monomer having a hydroxyl group, a (meth) acrylic monomer having a carboxylic acid group, and a (meth) acrylic monomer having an alkyl group Sensitive adhesive film for a polarizing plate.
The adhesive film for a polarizing plate according to claim 1, wherein the total of the first isocyanate curing agent and the second isocyanate curing agent is 20 parts by weight or less based on 100 parts by weight of the (meth) acrylic copolymer.
The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the pressure-sensitive adhesive composition for a polarizing plate further comprises a silane coupling agent.
A polarizing plate comprising the pressure-sensitive adhesive film for a polarizing plate according to any one of claims 1 to 11.
An optical display device comprising the polarizing plate of claim 12.

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