WO2015020325A1 - Adhesive composition and composite polarizing plate using same - Google Patents

Abstract

The present invention relates to an adhesive composition and a composite polarizing plate using same, more specifically to an adhesive composition and a composite polarizing plate using same in which the adhesive composition comprises a cross-linking agent and a water-soluble resin containing polyvinyl resin having a benzene ring on a side chain, thereby markedly improving the adhesiveness between a polarizer and a patterned retardation layer when utilized in producing a composite polarizing plate by adhering the polarizer and the patterned retardation layer, and and contributing to improving heat-resistance and moist-heat resistance as well as to facilitating adhesion to a display panel and the like when applied to image displaying apparatuses.

Description

Adhesive composition and composite polarizing plate using same

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

Displays such as liquid crystal displays for stereoscopic image implementation often include a patterned retardation film. The patterned retardation film configures the optical axis of each pattern region in different directions to implement a stereoscopic image by different images transmitted to the left and right eyes of a viewer wearing polarized glasses.

The patterned retardation film can typically be formed by forming an alignment film on a glass substrate and coating and aligning the liquid crystal on the alignment film. The photoreactive liquid crystal material is oriented on the alignment film and then crosslinked by light irradiation such as ultraviolet light to form a polymer liquid crystal film. At this time, the retarder pattern functions according to the alignment direction of the liquid crystal corresponding to the surface alignment of the alignment film.

The patterned retardation film is usually bonded to one side of the polarizing plate through an adhesive or a pressure-sensitive adhesive, and in recent years also bonded to one side of the polyvinyl alcohol polarizer for thinner film weight.

When the adhesion between the patterned retardation film and the polarizing plate or polarizer is poor, deformation may occur during handling or use during the process, and peeling or sliding may occur when exposed to high temperature and high humidity for a long time. In addition, the conventional polyvinyl alcohol polarizer may shrink in the stretching direction. Accordingly, the phase difference may be different for each position of the phase difference layer, thereby reducing the 3D stereoscopic feeling.

Accordingly, there is a need for development of an excellent adhesive having excellent bonding strength and even functions such as hot water resistance and heat and humidity resistance.

Korean Unexamined Patent Publication No. 2013-0028881 discloses a method for producing a film patterned retarder, a film patterned retarder, and a polarizing plate and an image display device having the same.

[Preceding technical literature]

[Patent Documents]

(Patent Document 1) Korean Patent Publication No. 2013-0028881

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive composition capable of remarkably improving the bonding force between a polarizer and a patterned retardation layer when used to produce a composite polarizing plate by bonding the polarizer and the patterned retardation layer.

An object of the present invention is to provide a composite polarizing plate bonded through the adhesive composition.

1. Adhesive composition containing water-soluble resin and crosslinking agent containing polyvinyl alcohol resin which has a benzene ring in a side chain.

2. In the above 1, wherein the polyvinyl alcohol resin is a hydroxyl group is modified with a substituent containing a benzene ring, adhesive composition.

3. In the above 2, wherein the substituent is a halogen element, a hydroxy group, a carboxy group, an amino group, a nitro group, an alkyl group having 1 to 12 carbon atoms or a benzoyloxy group unsubstituted or substituted with an aryl group having 6 to 8 carbon atoms, adhesive composition.

4. according to the above 2, the degree of denaturation to a substituent containing a benzene ring of the hydroxyl group is 10 to 30%, the adhesive composition.

5. according to the above 1, wherein the polyvinyl alcohol resin containing a benzene ring in the side chain is obtained by condensing a polyvinyl alcohol resin with an acyl chloride or acid anhydride containing a benzene ring.

6. according to the above 1, wherein the polyvinyl alcohol resin containing a benzene ring in the side chain is included in more than 10% by weight of the total weight of the water-soluble resin, adhesive composition.

7. In the above 1, the cross-linking agent is monoaldehyde, dialdehydes, amino-formaldehyde resin, glyoxalate, acetal compound, divalent metal, trivalent metal, tetravalent metal, metal chelate compounds, oxazoline Adhesive composition, which is at least one selected from the group consisting of resins, melamines, aziridines and polyvalent inorganic acids.

8. according to the above 1, wherein the cross-linking agent is included in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the water-soluble resin based on solids, adhesive composition.

9. A composite polarizing plate comprising a polarizer and a patterned retardation layer bonded to one surface of the polarizer via the adhesive composition of any one of claims 1 to 8.

10. In the above 9, wherein the polarizer is a film having a function of a protective film or a retardation film is bonded to the opposite side of the surface is bonded with the retardation layer, the composite polarizing plate.

11. The composite polarizing plate of 9 above, wherein the patterned retardation layer comprises a liquid crystal coating layer containing a reactive liquid crystal monomer including a benzene ring.

12. The composite polarizing plate of 9 above, wherein the patterned retardation layer does not include an alignment layer.

13. In the above 9, the corner portion is 휜 side to the patterned retardation layer side from the polarizer side, the composite polarizing plate.

14. The composite polarizer of 9 above, wherein the height difference between the polarizer center of gravity and the highest point of 5 cm from the center of gravity is at least 3 mm.

15. The composite polarizing plate of 9 above, wherein the peeling force between the polarizer and the patterned retardation layer is 2N / 25mm or more.

16. Image display device including the composite polarizing plate of 9 above.

The adhesive composition of the present invention significantly improves the bonding force between the polarizer and the patterned retardation layer when used to bond the polarizer and the patterned retardation layer to produce a composite polarizing plate.

The composite polarizing plate bonded with the adhesive composition of the present invention is excellent in heat resistance and heat and humidity resistance, and peeling and rolling phenomenon are suppressed even when exposed to high temperature and high humidity conditions for a long time.

The composite polarizing plate bonded with the adhesive composition of the present invention simultaneously has a polarizing function and an improved 3D stereoscopic effect.

The composite polarizing plate bonded with the adhesive composition of the present invention can be easily bonded to a display panel or the like when applied to an image display device.

1 shows the state immediately after the bonding of the composite polarizing plate bonded with the adhesive composition of the present invention and the state swelled by water absorption.

The present invention includes a water-soluble resin and a crosslinking agent comprising a polyvinyl alcohol resin having a benzene ring in the side chain, whereby the polarizer and the patterned retardation layer are used when bonding the polarizer and the patterned retardation layer to produce a composite polarizing plate. The present invention relates to an adhesive composition and a composite polarizing plate using the same, which significantly improve the bonding force therebetween, improve heat resistance and heat and moisture resistance, and facilitate bonding to a display panel when applied to an image display device.

Hereinafter, the present invention will be described in detail.

<Adhesive Composition>

The adhesive composition of this invention is a water-based adhesive composition and contains a water-soluble resin.

The water-soluble resin according to the present invention includes a polyvinyl alcohol resin having a benzene ring in the side chain.

The polyvinyl alcohol resin having a benzene ring in the side chain significantly improves the bonding force between the polarizer and the patterned retardation layer when the adhesive composition of the present invention is used to bond the polarizer and the patterned retardation layer to produce a composite polarizing plate. This is believed to be due to the pi bond interaction with the benzene ring contained in the liquid crystal coating layer of the patterned retardation layer. By improving the bonding strength, the heat resistance and the heat and humidity resistance are also improved.

In addition, it is judged that the hydroxyl group of the polyvinyl alcohol resin has an effect of improving adhesion by hydrogen bonding with the polar group included in the polarizer surface and the liquid crystal coating layer.

The polyvinyl alcohol resin including the benzene ring in the side chain according to the present invention has a structure in which the hydroxyl group of the polyvinyl alcohol is modified with a substituent containing a benzene ring.

The substituent is not particularly limited as long as it includes a benzene ring, for example, substituted or unsubstituted with a halogen element, a hydroxy group, a carboxy group, an amino group, a nitro group, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms, or the like. It may be a benzoyloxy group.

The degree of modification of the polyvinyl alcohol resin according to the present invention to the substituent containing the benzene ring is not particularly limited and may be appropriately selected within a range not lowering the solubility of the resin in the solvent while improving the bonding strength. For example, 10 to 30%. When the degree of denaturation is less than 10%, the effect of improving the bonding strength with the patterned retardation layer may be insignificant, and when the degree of denaturation is greater than 30%, the solubility of the resin in the solvent may be lowered, so that the effect of improving the bonding strength may be insignificant. This degree of denaturation can be calculated from the chemical shift of adjacent hydrogen in NMR (nuclear magnetic resonance spectroscopy) measurements.

Although the average degree of polymerization of the polyvinyl alcohol resin used for the production of the polyvinyl alcohol resin containing a benzene ring in the side chain according to the present invention is not particularly limited, the average degree of polymerization is 100 to 5000, preferably 1000 in consideration of adhesion. It is preferable that it is to 4000, and average saponification degree is 85-100 mol%, Preferably it is 90-100 mol%.

The polyvinyl alcohol resin including the benzene ring in the side chain according to the present invention may be obtained by reacting the polyvinyl alcohol resin and the compound containing the benzene ring by a known method. For example, it can be obtained by condensing an acyl chloride or acid anhydride containing a benzene ring with a polyvinyl alcohol resin.

The water soluble resin according to the present invention may further include a water soluble resin commonly used in the art.

The said water-soluble resin is not specifically limited, For example, partially saponified polyvinyl alcohol resin. Fully saponified polyvinyl alcohol resin, carboxyl group modified polyvinyl alcohol resin, acetoacetyl group modified polyvinyl alcohol resin, methylol group modified polyvinyl alcohol resin, amino group modified polyvinyl alcohol resin, water-dispersible polyacrylate resin, etc. are mentioned.

The polyvinyl alcohol resin including the benzene ring in the side chain according to the present invention is not particularly limited in the range capable of performing its function, for example, may be included in more than 10% by weight of the total weight of the water-soluble resin. . When the content is less than 10% by weight, the effect of improving the bonding strength is insignificant, and problems such as deterioration of durability may occur.

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

The crosslinking agent is not particularly limited and may be a crosslinking agent commonly used in the art. For example, monoaldehydes, such as formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde, etc .; Glyoxal, malondialdehyde, succinic aldehyde, glutaraldehyde, malealdehyde dialdehyde, phthalaldehyde, etc .; Amino-formaldehyde resins such as methylolurea, methylolmelamine, alkylated methylolurea, alkylated methylolated melamine, acetoguanamine, benzoguanamine and formaldehyde condensate; glyoxylic acid metal salts Examples include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, transition metals such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel and copper, zinc and aluminum). Glyoxylates such as glyoxylic acid amine salts (such as ammonia, monomethylamine, dimethylamine, trimethylamine, etc.); Divalent metals such as magnesium, calcium, aluminum, iron, nickel; methoxy bullet, bullet-diethoxy, acetal compounds of the bullet, such as a dialkoxy on; Trivalent metals; Tetravalent metals; Metal chelate compounds; Oxazolines; Melamines; Aziridines; Polyvalent inorganic acids, such as boric acid, phosphoric acid, and sulfuric acid, etc. are mentioned. These can be used individually or in mixture of 2 or more types.

The content of the crosslinking agent is not particularly limited, and may be included, for example, in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the total water-soluble resin based on solid content. When the content of the crosslinking agent is within the above range, the effect of improving the bonding strength between the polarizer and the patterned retardation layer is excellent.

<Complex Polarizer>

In addition, the present invention provides a composite polarizing plate manufactured using the adhesive composition.

The composite polarizing plate of the present invention includes a polarizer and a patterned retardation layer bonded to one surface of the polarizer through the adhesive composition.

In the composite polarizing plate of the present invention, the polarizer and the patterned retardation layer are bonded through the adhesive composition, and the bonding strength is excellent. In this case, as described above, the adhesive composition layer may form a hydrogen bond with the polarizer and may form a pi bond interaction with the patterned retardation layer.

The polarizer is generally used in the display field, and the polarizer is not limited as long as it can polarize incident light. For example, a film made of polyvinyl alcohol (PVA) may be used by dyeing iodine or dichroic dye and drawing it in a predetermined direction. On the opposite side of the surface to be bonded to the patterned retardation layer may be a film having a function of a protective film or retardation film is bonded.

The configuration of the patterned retardation layer is not particularly limited and may include a configuration generally used in the art. For example, it may have a structure laminated in the order of the substrate, the alignment film and the liquid crystal coating layer, or may be a structure that does not include the alignment film.

The patterned retardation layer is bonded so that the liquid crystal coating layer faces the polarizer.

The base material is not particularly limited as long as it is formed of a material having excellent transparency, mechanical strength, thermal stability, moisture shielding property, retardation uniformity, and isotropy. For example, the polyolefin resin, polyester resin, cellulose resin, and polycarbonate resin , Acrylic resin, styrene resin, vinyl chloride resin, amide resin, imide resin, polyether sulfone resin, sulfone resin, polyether sulfone resin, polyether ether ketone resin, sulfonated polyphenylene resin, A substrate formed of at least one material selected from the group consisting of vinyl alcohol resin, vinylidene chloride resin, vinyl butyral resin, allylate resin, polyoxymethylene resin and epoxy resin can be used.

When the patterned retardation layer includes an alignment layer, the alignment layer is formed by coating a composition for forming an alignment layer commonly used in the art on the substrate and imparting orientation, and then patterning the substrate to have different orientation directions. Can be.

The orientation providing method may include a rubbing method, a photo alignment method, and the like, and the patterning method may be based on a plurality of exposure processes using a photomask, but is not limited thereto.

The light used for the exposure is not particularly limited, but for example, polarized ultraviolet irradiation, ion beam or plasma beam irradiation, radiation irradiation, or the like can be used. For example, it is preferable to irradiate polarized ultraviolet rays.

The liquid crystal coating layer may be formed by applying a composition for forming a liquid crystal coating layer including a reactive liquid crystal monomer (RM) or the like commonly used in the art on an alignment layer and crosslinking the same.

The reactive liquid crystal monomer is not particularly limited and may be a monomer commonly used in the art, but preferably may be a monomer having a benzene ring.

When the patterned retardation layer does not include an alignment layer, the composition for forming a liquid crystal coating layer may be applied onto the substrate without the alignment layer, and may be exposed to simultaneously perform patterning and orientation to form a patterned retardation layer.

In this case, the composition for forming a liquid crystal coating layer may further include a compound which can be aligned by polarized ultraviolet light such as a linear photopolymerizable polymer for alignment.

When the patterned retardation layer does not include an alignment layer, a thinner display can be realized.

Typically, a polarizing plate is attached to a display panel or the like and applied to an image display device, but the composite polarizing plate of the present invention can be easily performed.

Specifically, the bonding by the water-based adhesive is carried out including a coating, bonding and drying step, because the polarizer and the protective film has a high hygroscopicity, and absorbs and expands after the drying step. In such a case, as illustrated in FIG. 1, the edge portion of the composite polarizing plate is bent from the polarizer side to the patterned retardation layer side, thereby facilitating easy bonding.

휜 degree is not particularly limited as long as the bonding can be easily made and does not affect the properties such as durability, for example, the height difference between the polarizer center of gravity and the point of 5cm from the center of gravity may be 3mm or more. If the degree of deflection is within the above range, the ease of joining can be maximized. Preferably from 3 to 5mm in that it has excellent physical properties and bonding properties.

The composite polarizing plate of the present invention prepared using the adhesive composition has excellent bonding strength between the polarizer and the patterned retardation layer. For example, the peeling force between the polarizer and the patterned retardation layer may be 2 N / 25 mm or more, preferably 2.5 to 5 N / 25 mm or more.

<Image display device>

In addition, the present invention provides an image display device including the composite polarizing plate.

The image display device is not particularly limited, and examples thereof include stereoscopic image implementation or semi-transmissive liquid crystal display device, plasma display device, organic EL display device, and the like.

The composite polarizing plate of the present invention can be used at a position where a conventional polarizing plate and a patterned retardation layer are stacked.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but these examples are merely illustrative of the present invention and are not intended to limit the scope of the appended claims, which are within the scope and spirit of the present invention. It is apparent to those skilled in the art that various changes and modifications can be made to the present invention, and such modifications and changes belong to the appended claims.

Preparation Example 1

10 g of polyvinyl alcohol resin (P2000, Nippon Synthetic Co., Ltd.) was dissolved in 100 ml of dimethyl sulfoxide (DMSO) at 50 ° C, and 10 g of benzoyl chloride was slowly added dropwise for 30 minutes using a funnel while stirring. Thereafter, the mixture was stirred at the same temperature for another 5 hours, cooled to room temperature, and the reaction mixture was added dropwise to 300 mL of acetone to form a precipitate. This was filtered with a glass filter and dried for 1 hour with hot air at 100 ° C.

The obtained product was partially dissolved in a solvent of DMSO-d6, and analyzed by NMR to compare the strength of the CH-OH peak and the CH-OBz peak to confirm that the polyvinyl alcohol having a degree of denaturation of 25% was added. 10 g of the reaction mixture was added to 500 mL of distilled water. It was dissolved by heating to 50 ℃ to prepare a 2% aqueous solution.

Preparation Example 2

Except for using 7g of benzoyl chloride was carried out in the same manner as in Preparation Example 1, to prepare a 2% aqueous solution of polyvinyl alcohol having a modification degree of 15%.

Preparation Example 3

A 2% aqueous solution of polyvinyl alcohol having a modification degree of 8% was prepared in the same manner as in Preparation Example 1, except that 2 g of benzoyl chloride was used.

Preparation Example 4

Except that 15 g of benzoyl chloride was used in the same manner as in Preparation Example 1, a polyvinyl alcohol 2% aqueous solution of 32% denaturation was prepared.

Examples and Comparative Examples

An adhesive composition having the ingredients and contents (solid content basis) described in Table 1 below was prepared.

Table 1

Comparative Example 3

A photopolymerizable adhesive composition was prepared by adding 1 part by weight of Igacure-184 (BASF) as an initiator based on 100 parts by weight of 2-hydroxy-3-phenoxypropylacrylate.

Experimental Example

(1) Peel force measurement

A polyvinyl alcohol polarizer having a patterned retardation layer (MPR32, DNP) and a triacetyl cellulose protective film bonded to one surface thereof, so that the liquid crystal coating layer and the polarizer were in contact, and using a roll laminator as an adhesive composition of Examples and Comparative Examples Splicing. For evaluation, the end portion was made free of adhesive.

Thereafter, the mixture was dried at 100 ° C. for 3 minutes and allowed to stand at room temperature for 48 hours to cure.

Peel force was measured by cutting the prepared composite polarizing plate sample in a width of 25mm, peeling at a rate of 300mm / min in the 180 degree peeling direction.

(2) Heat resistance and heat and humidity resistance evaluation

A composite polarizing plate was prepared in the same manner as in Experimental Example (1), an acrylic pressure-sensitive adhesive was applied to the protective film and cured, and then bonded to soda glass and autoclaved.

Thereafter, after 500 hours at 80 ° C., 60 ° C., and 500% at 90% RH, it was confirmed whether bubbles or peeling occurred at the bonding surface of the liquid crystal coating layer and the polarizer, respectively, and evaluated heat resistance and moisture heat resistance according to the following criteria. It was.

○ : no bubbles or peeling

(Triangle | delta) : There exist bubble or peeling, but it confirmed only to very small part.

X: Bubbles or peeling are easily visually confirmed

In the case of ○, the heat resistance and the moist heat resistance were evaluated as ○ only when the above criteria were met. In the case of Δ and X, only one of the heat resistance and the heat and humidity resistance was evaluated as Δ or X even when the criteria were met.

(3) bending degree measurement

The center of gravity of the composite polarizing plate manufactured in the same manner as in Experimental Example (1) was cut into 10 cm X 10 cm, and the patterned retardation layer was placed upward on a flat work surface.

Thereafter, the height from the work table to the center of the highest height 휜 side on the polarizer side was measured.

TABLE 2

Referring to Table 2, the composite polarizing plates bonded with the adhesive compositions of Examples 1, 2 and 5 to 7 has a very good peeling force of 2.8 N / 25mm or more, and no bubbles or peeling occur at all, and thus heat resistance and moisture and heat resistance. All of these were excellent. And it bent 3.5 mm or more and confirmed that the easy joining was possible.

The performance of the adhesive composition of Examples 3 and 4 in which the degree of modification of the water-soluble resin was outside the preferred range was slightly reduced, but still showed excellent performance.

The performance of Example 8 in which the content of the polyvinyl alcohol resin having a benzene ring in the side chain was outside the preferred range and Example 9 including the excessive amount of the crosslinking agent decreased slightly, but still showed excellent performance.

However, in the case of Comparative Examples 1-3, peeling force fell remarkably. In addition, in the case of Comparative Examples 1 and 2, the heat resistance and the heat-and-moisture resistance were inferior, and in the case of Comparative Example 3, it was confirmed that the bonding was not easy because it was not bent at all.

[Description of the code]

100: polarizer 200: adhesive layer

300: patterned retardation layer 400: protective film

Claims (16)

1. Adhesive composition containing water-soluble resin and crosslinking agent containing polyvinyl alcohol resin which has a benzene ring in a side chain.
2. The adhesive composition of claim 1, wherein the polyvinyl alcohol resin is a hydroxyl group modified with a substituent including a benzene ring.
3. The adhesive composition according to claim 2, wherein the substituent is a benzoyloxy group unsubstituted or substituted with a halogen element, a hydroxy group, a carboxy group, an amino group or a nitro group.
4. The adhesive composition of Claim 2 whose modification degree to the substituent containing a benzene ring of a hydroxyl group is 10 to 30%.
5. The adhesive composition according to claim 1, wherein the polyvinyl alcohol resin containing a benzene ring in the side chain is obtained by condensing an acyl chloride or an acid anhydride containing a benzene ring with a polyvinyl alcohol resin.
6. The adhesive composition of claim 1, wherein the polyvinyl alcohol resin including a benzene ring in the side chain is included in 10% by weight or more of the total weight of the water-soluble resin.
7. The method of claim 1, wherein the crosslinking agent is monoaldehyde, dialdehyde, amino-formaldehyde resin, glyoxalate, acetal compound, divalent metal, trivalent metal, tetravalent metal, metal chelate compounds, oxazolines, Adhesive composition which is at least one selected from the group consisting of melamines, aziridines and polyvalent inorganic acids.
8. The adhesive composition of claim 1, wherein the crosslinking agent is included in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the water-based resin based on a solid content.
9. Polarizer, and

   A composite polarizing plate comprising a patterned retardation layer bonded to one surface of the polarizer through the adhesive composition of any one of claims 1 to 8.
10. The composite polarizing plate according to claim 9, wherein the polarizer is a film having a function of a protective film or a retardation film bonded to the surface opposite to the surface to be bonded to the patterned retardation layer.
11. The composite polarizing plate according to claim 9, wherein the patterned retardation layer comprises a liquid crystal coating layer containing a reactive liquid crystal monomer comprising a benzene ring.
12. The composite polarizing plate according to claim 9, wherein the patterned retardation layer does not include an alignment film.
13. The composite polarizing plate according to claim 9, wherein the corner portion extends from the polarizer side to the patterned retardation layer side.
14. The composite polarizing plate according to claim 9, wherein an altitude difference between the polarizer center of gravity and the highest point of 5 cm from the center of gravity is at least 3 mm.
15. The composite polarizing plate according to claim 9, wherein the peeling force between the polarizer and the patterned retardation layer is 2 N / 25 mm or more.
16. An image display device comprising the composite polarizing plate of claim 9.

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