TW201516107A - Adhesive composition and composite polarization plate using the same - Google Patents

Abstract

Disclosed are an adhesive composition, including: a binder resin which is polymerized by including a styrene monomer having a hydroxyl group; and a cross-linking agent, thereby when the composite polarizing plate is fabricated by combining the polarizer with the patterned retardation layer using the adhesive composition of the present invention, adhesion between the polarizer and the patterned retardation layer is remarkably improved, and the adhesive composition has excellent thermal resistance and moist heat resistance, as well as improved 3D stereoscopic effects, and a composite polarizing plate using the same.

Description

Adhesive composition and composite polarizing plate using the same

The present invention relates to an adhesive composition and a composite polarizing plate using the same.

Generally, a display device for achieving a stereoscopic image, such as a liquid crystal display device, often includes a patterned retardation film. The retardation film has a technical configuration in which the optical axes of the separated pattern regions are formed in different directions from each other to transfer the separated images to the right and left eyes of the observer wearing one of the polarized glasses, thereby Three-dimensional (that is, three-dimensional) images.

The patterned retardation film is usually prepared by forming an alignment layer on a glass substrate and applying liquid crystal to the alignment layer to achieve alignment performance. A photosensitive liquid crystal material is aligned to the alignment layer and then crosslinked by light irradiation, such as ultraviolet light, to form a polymer liquid crystal film. The polymer liquid crystal film thus formed can be used as a retardant pattern depending on the alignment direction of the liquid crystal accompanying the surface alignment of the alignment layer.

The patterned retardation film is usually adhered to one side of a polarizing plate by a binder or an adhesive, and in recent years, the patterned retardation film has been adhered to a polyvinyl alcohol (polyvinyl) Alcohol) One side of a polarizer to reduce the thickness and weight of the display device.

When the adhesion between the patterned retardation film and a polarizing plate or polarizer is reduced, deformation may occur during processing or use in a manufacturing process. Furthermore, the occurrence of peel-off or thrust phenomenon is also of concern when exposed to heat and humidity for a long period of time. In addition, a typical polyethylene polarizer shrinks in a direction of stretching, thus involving different delays throughout a retardation layer, which in turn causes degradation of the 3D stereoscopic effect.

Therefore, there is still a need to develop an improved adhesive having various properties such as hot water resistance, moist heat resistance, and the like, as well as good adhesion.

Korean Patent Publication No. 2013-0028881 discloses a method for preparing a film type patterning retarder, a film type pattern retarder, and a polarizing plate and an image display device comprising the same.

Accordingly, it is an object of the present invention to provide an adhesive composition which can be significantly improved when it is used to fabricate a composite polarizer by incorporating a polarizer and a patterned retardation layer. Adhesive between the polarizer and the patterned retardation layer.

Another object of the present invention is to provide a composite polarizing plate which is manufactured by using the adhesive of the adhesive composition.

The above objects of the present invention are achieved by the following properties:

(1) An adhesive composition comprising: a binder resin which is polymerized by a monomer comprising styrene having one hydroxyl group; and a crosslinking agent.

(2) The composition according to the above (1), wherein the styrene single system having a hydroxyl group is represented by the following Chemical Formula 1:

(wherein R ₁ is a hydrogen atom or a monomethyl group; R ₂ is a direct bond, a straight chain or a branched alkylene group having 1 to 6 carbon atoms, -CO-, or -SO ₂ -; The alkylene group can be uncoupled by an oxygen atom).

(3) The composition according to the above (1), wherein the styrene monomer having a hydroxyl group is polymerized by an amount of 50 wt.% or more based on the total weight of the monomers.

(4) The composition according to the above (1), wherein the binder resin is polymerized by further containing an ionic monomer.

(5) The composition according to the above (4), wherein the ion single system is at least one selected from the group consisting of an ammonium acrylate salt, a styrene salt, and a vinyl imidazole salt.

(6) The composition according to the above (4), wherein the ionic monomer is contained in an amount of from 7 to 30% by weight based on the total weight of the monomers.

(7) The composition according to the above (1), wherein the binder resin is polymerized by at least one of an acrylic monomer further comprising one hydroxyl group and one acrylic monomer having one carboxyl group.

(8) The composition according to the above (7), wherein the acrylic monomer having a hydroxyl group and the acrylic monomer having a carboxyl group are contained in an amount of 7 to 30 wt.% based on the total weight of the monomers. .

(9) The composition according to the above (1), wherein the crosslinking agent is selected from the group consisting of a monoaldehyde, a dialdehyde, an amino aldehyde resin, a glyoxylic acid, an acetal compound, a divalent metal, and a divalent metal salt. , trivalent metals, tetravalent metals, metal chelate compounds, Oxazoline, melamine, nitrogen And at least one of the group consisting of polybasic acids.

(10) A composite polarizing plate comprising: a polarizer; and a patterned retardation layer which is adhered using the adhesive compound according to any one of (1) to (9) above On one side of the polarizer.

(11) The composition according to the above (10), wherein the polarizer comprises a film having a protective film function or a function of a retardation film adhered to the opposite surface of the adhesive surface of the patterned retardation layer. a film.

(12) The polarizing plate according to (10) above, wherein the patterned retardation layer comprises a liquid crystal coating layer comprising a reactive liquid crystal monomer having a benzene ring.

(13) The polarizing plate according to (10) above, wherein the patterned retardation layer does not include an alignment layer.

(14) The polarizing plate according to (10) above, wherein a peeling strength between the polarizing plate and the patterned retardation layer is 1.0 N/25 mm or more.

(15) An image display device comprising the composite polarizing plate according to (10) above.

When a polarizer and a patterned retardation layer are combined to form a composite polarizing plate by using the adhesive composition of the present invention, the adhesion between the polarizer and the patterned retardation layer is significantly improved. .

The composite polarizing plate produced by using the adhesive composition of the present invention has good heat resistance and moist heat resistance, thereby suppressing occurrence of peel-off or a thrust phenomenon, even if It is exposed to heat and humidity for a long time.

A composite polarizing plate manufactured by using the adhesive composition of the present invention can have both a polarizing property and an improved 3D stereoscopic effect.

The present invention discloses an adhesive composition, and a composite polarizing plate using the same, the adhesive composition comprising: a binder resin, which is polymerized by a styrene monomer having one hydroxyl group; And a cross-linking agent, whereby the composite polarizing plate is formed by using the adhesive composition of the present invention in combination with the polarizer and a patterned retardation layer, and the polarizer and the patterning The adhesion between the retardation layers is remarkably improved, and the adhesive composition has good heat resistance and moist heat resistance, as well as an improved 3D stereoscopic effect.

Hereinafter, the present invention will be described in more detail.

Adhesive composition

The adhesive composition of the present invention is an aqueous adhesive composition and may comprise a binder resin.

The binder resin according to the present invention is polymerized by a monomer comprising styrene having one hydroxyl group.

The adhesive composition of the present invention has good adhesion when it is used in combination with a polarizer and a patterned retardation layer, and the improved adhesion enhances heat resistance and moist heat resistance. The reason for this result is considered to be that the styrene monomer according to the present invention has a hydroxyl group, and the one hydroxyl group is bonded to a polar group on the surface of the polarizer and the liquid crystal of the patterned retardation layer The other polar group included in the coating layer is formed to form a hydrogen bond, and the benzene ring-based chain contained in the styrene monomer is contained in the liquid crystal coating layer of the patterned retardation layer. A benzene ring to effect a π bond interaction.

The styrene monomer having a monohydroxy group according to the present invention is not particularly limited but may contain, for example, one of the monomers represented by the following Chemical Formula 1:

(wherein R ₁ is a hydrogen atom or a methyl group;

R ₂ is a direct bond, a straight chain or a branched alkylene group having 1 to 6 carbon atoms, -CO-, or -SO ₂ -;

The alkylene group can be uncoupled by an oxygen atom).

More specifically, the styrene monomer having a monohydroxy group may contain, for example, a substance represented by Chemical Formulas a-1 to a-5, which may be used singly or in combination of two or more thereof. Wherein, a single system represented by the chemical formula a-4 has a carboxyl group, but the R ₂ in the chemical formula 1 is -CO- having an OH group, and one represented by the chemical formula a-5 The single system has a monosulfonic acid group, but the R ₂ in the chemical formula 1 is -SO ₂ - having an OH group, and since both are within the scope of the above chemical formula 1, it can be interpreted as They are included in the styrene monomer having a monohydroxy group of the present invention.

The content of the styrene monomer having a monohydroxy group is not particularly limited as long as the content may achieve the above properties and, for example, may be contained in an amount of 50 wt.% or more with respect to the total weight of one of the monomers. Being aggregated. If the content is within the above range, adhesion between the polarizer and the patterned retardation layer can be maximized. In this regard, it is preferred that the styrene single system having a hydroxyl group is contained in an amount of from 50 to 85 wt.%, based on the total weight of one of the monomers.

The binder resin according to the present invention can be polymerized by further containing an ionic monomer. In this case, when the occurrence of volatilization due to residual impurities and deterioration of viscous properties are suppressed, the solubility in the solvent can be remarkably improved to improve adhesion.

The ionic monomer to be used in accordance with the present invention is not particularly limited as long as it exhibits the above properties, and may contain, for example, an ammonium acrylate, a styrene ammonium salt, a vinyl imidazolium salt or the like. More specifically, the monomer represented by the following Chemical Formula 2 to Chemical Formula 6 can be exemplified. These monomers may be used singly or in combination of two or more thereof.

The content of the ionic monomer is not particularly limited as long as it can achieve the above properties and, for example, can be contained in an amount of 7 to 30 wt.% with respect to the total weight of one of the monomers. If the ionic monomer content is less than 7 wt.%, the effect of improving the solubility may be insignificant, and when the content exceeds 30 wt.%, the heat and humidity resistance and adhesion may be degraded.

The molecular weight of the binder resin is not particularly limited, but may be, for example, in the range of 5,000 to 100,000 in terms of weight average molecular weight.

The binder resin can be prepared by any conventional method for polymerization, and its weight average molecular weight can be changed by, for example, changing the content of the polymerization initiator, the reaction temperature, the reaction time, the type and content of the catalyst, and the use of other components. Or, some conditions of the same are controlled. The kind of the solvent and the polymerization initiator are not particularly limited, but any conventional solvent and polymerization initiator known in the related art can be used.

When necessary, the binder resin according to the present invention can be polymerized by at least one of an acrylic monomer further having a hydroxyl group and an acrylic monomer having a carboxyl group. When the binder resin is polymerized by an acrylic monomer further comprising a hydroxyl group or a carboxyl group, the wettability of the resin can be enhanced, and thereby the adhesion thereof is further improved.

The acrylic monomer having a monohydroxy group according to the present invention can be represented by the following Chemical Formula 7:

(wherein R ₁ is a hydrogen atom or a monomethyl group, X is a hydrogen atom or -NH-, and R ₂ is a straight chain or a branched alkylene group having 1 to 6 carbon atoms, the branched chain The alkyl group may be unlinked by a cycloalkylene group having 3 to 6 carbon atoms.

More specifically, the acrylic monomer having a carboxyl group contains, for example, those represented by Chemical Formula b-1 to Chemical Formula b-9, and these may be used singly or in combination of two or more thereof.

More specifically, the acrylic monomer having a carboxyl group contains, for example, those represented by the chemical formula c-1 to the chemical formula c-6, and these may be used singly or in combination of two or more thereof.

The acrylic monomer having a monohydroxy group and the acrylic monomer having a carboxyl group may be contained in an amount of from 7 to 30 wt.% based on the total weight of one of the monomers. If the ionic monomer content is less than 7 wt.%, the effect of improving wettability may be insignificant, and when the content thereof exceeds 30 wt.%, the interaction with the patterned retardation layer may be degraded, and Therefore, reduce it to stick to it.

The adhesive composition of the present invention may further comprise a crosslinking agent.

The crosslinking agent is not particularly limited, but may further contain any conventional crosslinking agent used in the related art. The following can be used: for example, mono-aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, etc.; dialdehydes such as glyoxal, malondialdehyde, butyl Succindialdehyde, glutardialdehyde, maleindialdehyde, phthaldialdehyde, etc.; amino-formaldehyde resins such as formaldehyde and methylol urea ), methylol melamine, methylolurea alkylate, methylolmelamine alkylate, acetamidine (acetoguanamine) or benzoquinone a condensation product of (benzoguanamine) or the like; glyoxylates, such as glyoxylic acid metal salts (metals include, for example, alkali metals such as lithium, sodium, potassium, etc.; alkaline earths such as magnesium , calcium, etc.; transition metals such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, etc., zinc, aluminum or the like; glyoxylic acid amine salts (amines, for example, Ammonia, monomethylamine, dimethylamine, trimethylamine, etc.; acetal compounds such as dimethoxyethanal, diethoxy acetaldehyde (diethoxyethanal), dialkoxyethanal, etc.; divalent metals such as magnesium, calcium, aluminum, iron, nickel, etc., or salts thereof; trivalent metals; tetravalent metals; metal chelate compounds, Oxazolines, melamines, aziridines; poly-inorganic acids such as boric acid, phosphoric acid, sulfuric acid, etc.; or the like. These materials may be used singly or in combination of two or more thereof.

The content of the crosslinking agent is not particularly limited, but may be included in the range of 0.5 to 20 wt.% with respect to 100 wt. part of the binder. If the content of the crosslinking agent is within the above range, the effect of improving adhesion between the polarizer and the patterned retardation layer can be improved.

Composite polarizer

Further, the present invention provides a composite polarizing plate produced by using the adhesive composition as described above.

The composite polarizing plate of the present invention may comprise a polarizer and a retardation layer patterned by one of the sides of the polarizer by the adhesive composition.

Since the polarizer is combined with the patterned retardation layer using the above adhesive composition, the composite polarizing plate of the present invention can have high adhesion. In this regard, as explained above, an adhesive composition layer can form a hydrogen bond with the polarizer together with a π-bond interaction with the patterned retardation layer.

The polarizer is not particularly limited as long as it is a general user in the field of display and can polarize incident light. For example, a product obtained by dyeing a film of polyvinyl alcohol as a base with iodine or a dichroic dye and then stretching the dyed film in a desired direction can be used. A film having a protective film function or a film having a function of a retardation film may be adhered to a face opposite to the face to which the patterned retardation layer is adhered.

The configuration of one of the patterning delay layers is not particularly limited, but may include any configuration commonly used in the field. For example, a substrate, an alignment layer, and a liquid crystal coating layer may be laminated in this order to form a laminate structure. Alternatively, the structure may not include the alignment layer.

The patterned retardation layer can be adhered to allow the liquid crystal coating layer to be applied to the polarizer.

The substrate is not particularly limited as long as it is made of a material having excellent properties such as transparency, mechanical strength, heat resistance, moisture barrier properties, retardation uniformity, isotropic properties or the like. For example, it is selected from the group consisting of a polyolefin resin, a polyester resin, a cellulose resin, a polycarbonate resin, an acryl resin, and a benzoic acid resin. Resin), vinyl chloride resin, amide resin, imide resin, polyether sulfone resin, sulfone resin, polyether ether Polyetherether sulfone resin, polyetherether ketone resin, polyphenylene sulfide resin, vinylalcohol resin, vinylidene chloride resin, vinyl alcohol A substrate made of at least one of a group consisting of a vinyl butyral resin, an allylate resin, a polyoxymethylene resin, and an epoxy resin can be used. .

When the patterned retardation layer comprises an alignment layer, the alignment layer can be formed by applying a composition for forming the alignment layer to the substrate, the composition being a common user in the field to provide alignment The nature, and then, the coating is patterned to have different orientation directions.

The method for providing alignment characteristics can include, for example, rubbing, alignment of light, etc., and the patterning method can include a multiple exposure process using a reticle. However, the method for providing alignment properties and/or the patterning method is not particularly limited.

The light used for exposure is not particularly limited, but may include, for example, polarized ultraviolet radiation, an ionic beam or a plasma beam, and an irradiation at a desired angle. Or similar. For example, a polarized ultraviolet light system is preferably used.

The liquid crystal layer can be formed by applying a composition for forming the liquid crystal coating layer, which includes a reactive liquid crystal monomer (RM) and is generally used in the field, to the alignment layer, and then crosslinking the material.

The RM is not particularly limited, but may include any monomer generally used in the art, and preferably has one monomer of a benzene ring.

When the patterned retardation layer does not include the alignment layer, a patterned retardation layer can be formed by applying a composition for forming a liquid crystal coating layer to the substrate without the alignment layer, and then The object is exposed to simultaneously perform patterning and alignment.

In this case, the composition for forming a liquid crystal coating layer may further comprise any compound which may be aligned by polarized UV light, such as a linear photopolymerizable polymer, to effect alignment.

In the case where the patterned retardation layer does not include the alignment layer, a thin film display having a smaller thickness can be achieved as compared with the case of including the alignment layer.

The composite polarizing plate produced using the adhesive composition of the present invention exhibits good adhesion between a polarizer and a patterned retardation layer. For example, the peel strength applied between a polarizer and a patterned retardation layer may be 1.0 N/25 mm or higher, and preferably, the range is from 1.0 to 3.0 N/25 mm.

Image display device

Further, the present invention provides an image display apparatus comprising the composite polarizing plate as described above.

The image display device is not particularly limited, but may include a liquid crystal display device (for example, for achieving a stereoscopic image) or a transflective liquid crystal display device, a plasma display device, an organic EL display device, or the like.

The composite polarizing plate of the present invention can be provided at a position where a polarizing plate and a patterned retardation layer are generally formed as a laminate.

Hereinafter, preferred embodiments are presented to more specifically describe the present invention. However, it will be apparent to those skilled in the <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; The scope defined by the scope of patents.

example

Examples and comparative examples

The adhesive composition has been prepared from compositions of different compositions, and the contents are listed in Table 1 below. The binder resin was thus prepared to have a weight average molecular weight of 10,000 g/mol.

Experimental example

(1) Measurement of peel strength

a polyvinyl alcohol polarizer comprising a patterned retardation layer (MPR32, DNP Co.) and a triethylene glycol protective film adhered to one side thereof is placed in contact with a liquid crystal coating layer and used in each The adhesive composition prepared in the examples and comparative examples was adhered thereto by a roll laminator. For evaluation, the end portions of the laminate were not coated with the adhesive composition.

Thereafter, the treated product was dried at 100 ° C for 3 minutes, and then left at room temperature for 48 hours depending on the state, thereby being hardened.

After the composite polarizing plate manufactured as described above is cut into a sample having a width of 25 mm, the sample is subjected to peeling at a peeling rate of 300 mm/min in a peeling direction of 180°, and then the amount of the peeling strength is performed. Measurement.

(2) Evaluation of heat resistance and heat and humidity resistance

A composite polarizing plate was fabricated in accordance with the same procedure as described in Experimental Example (1). After applying an acrylic adhesive to the protective film and hardening the material, the hardened film is adhered to a soda silicate glass and subjected to an autoclave treatment.

Next, the heat resistance and the moist heat resistance test of the individual composite polarizing plates were carried out.

After the treated film was left at 80 ° C for 500 hours, 60 ° C, and 90% RH for 500 hours, it was investigated whether bubbles or peeling occurred on the adhesive surface between the polarizer and the liquid crystal coating layer. The results of this survey were used to evaluate heat resistance and heat and humidity resistance according to the following evaluation criteria.

◎: No bubbles or peeling were observed

○: Bubbles or peeling of a very small area were observed

△: slight observation of bubbles or peeling

X: In a considerable area, bubbles or peeling can be easily observed visually

Referring to Table 2 above, it was confirmed that the composite polarizing plates prepared in Examples 1 to 17 have high peel strength and enhanced resistance by good heat resistance and moist heat resistance.

However, it was confirmed that the composite polarizing plates prepared in Comparative Examples 1 to 8 have a relatively low peel strength, and a very low tolerance of the plural bubbles and peeling generated in the evaluation of heat resistance and moist heat resistance.

Claims (15)

[Item 1] An adhesive composition comprising:
A binder resin which is polymerized by a monomer comprising styrene having one hydroxyl group; and a crosslinking agent. [Item 2] The composition according to claim 1, wherein the styrene single system having a hydroxyl group is represented by the following Chemical Formula 1,

(wherein R ₁ is a hydrogen atom or a monomethyl group; R ₂ is a direct bond, a straight chain or a branched alkylene group having 1 to 6 carbon atoms, -CO-, or -SO ₂ -; The alkylene group can be uncoupled by an oxygen atom). [Item 3] The composition of claim 1, wherein the styrene monomer having a hydroxyl group is polymerized in an amount of 50 wt.% or more based on the total weight of one of the monomers. [Item 4] The composition of claim 1, wherein the binder resin is polymerized by further comprising an ionic monomer. [Item 5] The composition of claim 4, wherein the ion monosystem is at least one selected from the group consisting of ammonium acrylate, styrene, and vinyl imidazolium. [Item 6] The composition of claim 4, wherein the ionic monomer is included in an amount of from 7 to 30 wt.%, based on the total weight of one of the monomers. [Item 7] The composition of claim 1, wherein the binder resin is polymerized by at least one of an acrylic monomer further comprising one hydroxyl group and one acrylic monomer having one carboxyl group. [Item 8] The composition of claim 7, wherein the acrylic monomer having a hydroxyl group and the acrylic monomer having a carboxyl group is 7 to 30 wt.% based on the total weight of the monomer. The quantity is included. [Item 9] The composition of claim 1, wherein the crosslinking agent is selected from the group consisting of a monoaldehyde, a dialdehyde, an amino aldehyde resin, a glyoxylic acid, an acetal compound, a divalent metal, a divalent metal salt, Trivalent metal, tetravalent metal, metal chelate compound, Oxazoline, melamine, nitrogen And at least one of the group consisting of polybasic acids. [Item 10] A composite polarizing plate comprising:
A polarizer; and a patterned retardation layer adhered to one side of the polarizer using the adhesive compound according to any one of claims 1 to 9. [Item 11] The composite polarizing plate of claim 10, wherein the polarizer comprises a film having a protective film function or a function of a retardation film adhered to the opposite surface of the adhesive surface of the patterned retardation layer. a film. [Item 12] The composition of claim 10, wherein the patterned retardation layer comprises a liquid crystal coating layer comprising a reactive liquid crystal monomer having a benzene ring. [Item 13] The composition of claim 10, wherein the patterned retardation layer does not comprise an alignment layer. [Item 14] The composition of claim 10, wherein a peel strength between the polarizer and the patterned retardation layer is 1.0 N/25 mm or more. [Item 15] An image display device comprising the composite polarizing plate according to claim 10 of the patent application.