WO2015060535A1 - Adhesive composition and composite polarizing plate using same - Google Patents

Abstract

The present invention relates to an adhesive composition and, more specifically, to an adhesive composition comprising a photopolymerizable compound, which comprises a styrene-based monomer having a hydroxyl group which is expressed by chemical formula (1), and a photopolymerization initiator, and thereby, when used for manufacturing a composite polarizing plate by adhering a polarizer and a patterned phase difference layer, significantly improving the adhesiveness between the polarizer and the patterned phase difference layer, improving heat and humidity resistance, and providing an excellent 3D effect.

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, and 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

An object of the present invention is to provide an adhesive composition capable of significantly improving the bonding force between a polarizer and a patterned retardation layer when used to bond a polarizer and a patterned retardation layer to produce a composite polarizing plate.

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

1. An adhesive composition comprising a photopolymerizable compound and a photopolymerization initiator comprising a styrene monomer having a hydroxy group represented by the following formula (1).

[Formula 1]

(Wherein R ₁ is a hydrogen atom or a methyl group,

R ₂ is a direct bond, a linear or branched alkylene group having 1 to 6 carbon atoms, -CO- or -SO _2- ,

The alkylene group may be interrupted by an oxygen atom).

2. according to the above 1, wherein the styrene-based monomer having a hydroxyl group is included in more than 50% by weight of the total weight of the monomer, the adhesive composition.

3. In the above 1, wherein the photopolymerizable compound further comprises at least one of an acrylic monomer having a hydroxy group and an acrylic monomer having a carboxyl group, the adhesive composition.

4. In the above 3, the acrylic monomer having a hydroxy group and the acrylic monomer having a carboxyl group is the total content of 9 to 45% by weight of the total monomer, the adhesive composition.

5. according to the above 1, wherein the photopolymerizable compound further comprises a polyfunctional acrylic monomer or a styrene monomer that does not contain a hydroxyl group, the adhesive composition.

6. In the above 5, the polyfunctional acrylic monomer or styrene-based monomer that does not contain a hydroxyl group is included in 0.1 to 5% by weight of the total weight of the monomer, the adhesive composition.

7. In the above 1, wherein the photopolymerization initiator is a radical photopolymerization initiator containing at least one selected from the group consisting of acetophenone-based, benzophenone-based, thioxanthone-based, benzoin-based and benzoin alkyl ether-based, adhesive composition.

8. polarizer, and

Composite polarizing plate comprising a patterned retardation layer bonded to one surface of the polarizer through the adhesive composition of any one of 1 to 7 above.

9. In the above 8, 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 to be bonded to the patterned retardation layer, a composite polarizing plate.

10. The composite polarizing plate of claim 8, wherein the patterned retardation layer includes a liquid crystal coating layer containing a reactive liquid crystal monomer including a benzene ring.

11. The composite polarizing plate of 8 above, wherein the peeling force between the polarizer and the patterned retardation layer is 1.0 N / 25 mm or more.

12. In the above 8, wherein the patterned retardation layer does not include an alignment layer, a composite polarizing plate.

13. Image display device including the composite polarizing plate of the above eight.

The pressure-sensitive 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 pressure-sensitive adhesive composition of the present invention is excellent in heat resistance and heat-and-moisture resistance, and even when exposed to high temperature and high humidity conditions for a long time, peeling and rolling phenomenon are suppressed.

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

The present invention includes a photopolymerizable compound comprising a styrene-based monomer having a hydroxy group represented by the formula (1) and a photopolymerization initiator, when the polarizer and the patterned retardation layer is bonded to produce a composite polarizing plate, the polarizer and the patterning The present invention relates to an adhesive composition which significantly improves the bonding force between the phase retardation layers, improves heat resistance and heat-and-moisture resistance, and has excellent 3D steric effect.

Hereinafter, the present invention will be described in detail.

Adhesive composition

The adhesive composition of this invention contains the photopolymerizable compound containing the styrene-type monomer which has a hydroxyl group.

The adhesive composition of the present invention has excellent bonding strength when used to bond the polarizer and the patterned retardation layer, and heat and moisture resistance are also improved by such bonding strength improvement. This is a styrene-based monomer according to the invention comprises a hydroxyl group, the hydroxy group is a hydrogen bond with the polar group contained in the liquid crystal coating layer of the polarizer surface polar group and the patterned retardation layer, the benzene ring of the styrene monomer is a patterned phase difference It is judged by the pi bond interaction with the benzene ring contained in the liquid crystal coating layer of the layer.

The styrenic monomer having a hydroxy group according to the present invention is represented by the following formula (1):

[Formula 1]

(Wherein R ₁ is hydrogen or a methyl group,

R ₂ is a direct bond, a linear or branched alkylene group having 1 to 6 carbon atoms, -CO- or -SO _2- ,

The alkylene group may be interrupted by oxygen).

Specific examples of the styrene-based monomer having a hydroxy group include the following formulas a-1 to a-5, which may be used alone or in combination of two or more. However, the monomer of Formula (a-4) has a carboxy group but has -OH and R ₂ in Formula 1 is -CO-, and the monomer of Formula (a-5) has a sulfonic acid group but has -OH group In the case where R ₂ is -SO _2- , all fall within the range of the formula (1), it is interpreted that it is included in the styrene monomer having a hydroxyl group of the present invention.

[Formula a-1]

[Formula a-2]

[Formula a-3]

[Formula a-4]

[Formula a-5]

The styrene-based monomer having a hydroxyl group is not particularly limited in the content within the range capable of performing the above function, for example, may be included at least 50% by weight of the total weight of the entire monomer. When the content is within the above range, it is possible to maximize the bonding force between the polarizer and the patterned retardation layer. In such aspect, it may preferably be included in 50 to 90% by weight of the total weight of the monomers.

The photopolymerizable compound according to the present invention may further include at least one of an acrylic monomer having a hydroxy group and an acrylic monomer having a carboxyl group. The styrene monomer and the acrylic monomer have different curing speeds, and when the acrylic monomer having a hydroxyl group or a carboxyl group is further included, an acrylic polymer is partially formed, which alleviates the cure shrinkage stress of the styrene polymer and the wettability of the adhesive composition. To further improve the peeling force.

Acrylic monomers having a hydroxyl group according to the present invention may be represented by the following formula (2):

[Formula 2]

Wherein R ₁ is hydrogen or methyl, X is oxygen or —NH—, R ₂ is a straight or branched chain alkylene group having 1 to 6 carbon atoms and is interrupted by a cycloalkylene group having 3 to 6 carbon atoms Can be).

Specific examples of the acrylic monomer having a hydroxy group according to the present invention include the following formula b-1 to formula b-6, which may be used alone or mixed two or more kinds.

[Formula b-1]

[Formula b-2]

[Formula b-3]

[Formula b-4]

[Formula b-5]

[Formula b-6]

Specific examples of the acrylic monomer having a carboxyl group according to the present invention include the following formulas c-1 to c-9, which may be used alone or in combination of two or more.

[Formula c-1]

[Formula c-2]

[Formula c-3]

[Formula c-4]

[Formula c-5]

[Formula c-6]

[Formula c-7]

[Formula c-8]

[Formula c-9]

The acrylic monomer having a hydroxy group and the acrylic monomer having a carboxyl group may be included in the total content of 9 to 45% by weight of the total weight of the monomer. If the content is in the above range, it is possible to maximize the effect of improving the bonding strength.

In addition, the photopolymerizable compound of the present invention may further include a polyfunctional acrylic monomer or a styrene monomer having no hydroxy group, which is commonly used in the art within the scope of not impairing the object of the present invention.

The polyfunctional acrylate improves the cohesion of the adhesive composition, thereby suppressing bubble generation under heat-resistant conditions and thus improving heat resistance.

The kind of the polyfunctional acrylic monomer is not particularly limited, and for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, and propionic acid-modified trimethylol Propane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (meth) acryloxyethyl isocyanur Trifunctional monomers such as acrylate and glycerol tri (meth) acrylate; Tetrafunctional monomers such as diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and tetramethylolpropane tetra (meth) acrylate; Pentafunctional monomers such as dipentaerythritol penta (meth) acrylate and propionic acid-modified dipentaerythritol penta (meth) acrylate; 6-functional monomers, such as dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, and isocyanate-modified urethane hexa (meth) acrylate, etc. are mentioned. These can be used individually or in mixture of 2 or more types.

Styrene-based monomers having no hydroxy group improve moist heat resistance.

The kind of the styrene-based monomer having no hydroxy group is not particularly limited, and examples thereof include styrene, vinyltoluene, α-methylstyrene, dimethyl styrene, chlorostyrene, bromostyrene, t-butylstyrene, methoxy styrene, and cyano styrene. Etc. can be mentioned. These can be used individually or in mixture of 2 or more types.

The content of the polyfunctional acrylic monomer or the styrene monomer having no hydroxy group is not particularly limited, and may be, for example, 0.1 to 5% by weight of the total weight of the total monomers. When the content of the polyfunctional acrylic monomer or the styrene monomer having no hydroxy group is less than 0.1% by weight, the effect of improving durability may be insignificant. When the content of the polyfunctional acrylic monomer is more than 5% by weight, the adhesion may be slightly lowered, and even when the content of the styrene-based monomer having no hydroxy group is more than 5% by weight, the adhesion may be lowered and heat resistance may be slightly lowered. .

The adhesive composition of the present invention further includes a photopolymerization initiator.

A photoinitiator is not specifically limited, For example, radical photoinitiators, such as an acetophenone type, a benzophenone type, a thioxanthone type, a benzoin type, and a benzoin alkyl ether type, are mentioned. These can be used individually or in mixture of 2 or more types.

Specific examples include acetophenone, hydroxydimethylacetophenone, dimethylaminoacetophenone, dimethoxy-2-phenylacetophenone, 3-methylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-die Methoxy-2-phenylacetophenone, 4-chronolocetophenone, 4,4-dimethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-hydroxycyclophenylketone, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2 -(Hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-diaminobenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, anthraquinone, 2-methyl Anthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethyl thi Oxanthone, 2,4-diethyl thioxanthone, benzoin, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, diphenyl ketone benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, 2, 4,6-trimethylbenzoyldiphenylphosphine oxide, fluorene, triphenylamine, carbazole, and the like, but are not limited thereto.

Available products on the market include Shiva's darocur 1173, darocur 4265, darocur BP, darocur TPO, darocur MBF, irgacure 184, irgacure 500, irgacure 2959, irgacure 754, irgacure 651, irgacure 369, irgacure 907, irgacure 1300, irgacure 819, irgacure 2022, irgacure 819DW, irgacure 2100, irgacure 784, irgacure 250, etc. are mentioned. These can be used individually or in mixture of 2 or more types.

The content of the photopolymerization initiator is not particularly limited, and may be included, for example, in an amount of 0.1 to 10 parts by weight, and preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the photopolymerizable compound. When the content of the photopolymerization initiator is less than 0.1 part by weight, the curing speed may be slow and sufficient curing may be difficult to proceed, and when the content of the photopolymerization initiator is more than 10 parts by weight, the durability of the adhesive layer may be lowered.

<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 hydrogen bonds with the polarizer, and may form hydrogen bonds and pi-pi interactions 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), which is 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 may preferably 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.

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 1.0 N / 25 mm or more, preferably 1.0 to 3.0 N / 25 mm.

<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.

Examples and Comparative Examples

To prepare an adhesive composition having the composition and content of Table 1.

Table 1

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.

Subsequently, the adhesive composition was cured by irradiating UV with a wavelength of 313 nm with a light amount of 2000 mJ / cm ² using a UV exposure machine (Fusion).

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 subjected to autoclave treatment.

Thereafter, heat and moisture resistance tests of each composite polarizer were performed.

The heat resistance test was performed at 80 ° C. for 500 hours and the humidity and heat resistance test at 60 ° C. and 90% RH for 500 hours, and then confirmed the occurrence of bubbles or peeling at the bonding surface of the liquid crystal coating layer and the polarizer. The heat and humidity resistance was evaluated.

◎: no bubbles or peeling

(Circle): There is bubble or peeling, but it is confirmed only to a very small part

(Triangle | delta): Bubble or peeling is confirmed to some extent.

X: Bubbles or peelings are easily visually confirmed over a considerable area

TABLE 2

division	Peeling force (N / 25mm)	Heat resistance	Moisture and Heat Resistance
Example 1	1.5	○	○
Example 2	1.3	○	○
Example 3	1.9	○	○
Example 4	2.3	○	○
Example 5	2.3	○	○
Example 6	2.9	◎	◎
Example 7	2.7	◎	◎
Example 8	2.1	○	○
Example 9	2.2	○	◎
Example 10	1.4	○	○
Example 11	1.2	○	◎
Example 12	2.3	◎	○
Example 13	1.2	○	○
Example 14	1.8	◎	○
Example 15	1.7	○	○
Example 16	2.0	○	○
Example 17	1.9	○	○
Comparative Example 1	0.5	△	△
Comparative Example 2	0.7	△	△
Comparative Example 3	0.8	△	○
Comparative Example 4	0.2	X	X
Comparative Example 5	0.3	X	X

Referring to Table 2, it was confirmed that the composite polarizing plates of Examples 1 to 17 were excellent in peel force, excellent in heat resistance and heat and moisture resistance, and have excellent durability.

However, it was confirmed that the composite polarizing plates of Comparative Examples 1 to 5 were remarkably inferior in peeling force, numerous bubbles and peelings occurred at the time of evaluation of heat resistance and heat and humidity resistance, and durability was remarkably low.

Claims (13)

1. Adhesive composition containing a photopolymerizable compound and a photoinitiator containing the styrene-type monomer which has a hydroxyl group represented by following formula (1).

   [Formula 1]

   

   (Wherein R ₁ is a hydrogen atom or a methyl group,

   R ₂ is a direct bond, a linear or branched alkylene group having 1 to 6 carbon atoms, -CO- or -SO _2- ,

   The alkylene group may be interrupted by an oxygen atom).
2. The adhesive composition of claim 1, wherein the styrene-based monomer having a hydroxyl group is included in 50% by weight or more of the total weight of the monomers.
3. The adhesive composition of claim 1, wherein the photopolymerizable compound further comprises at least one of an acrylic monomer having a hydroxy group and an acrylic monomer having a carboxyl group.
4. The adhesive composition according to claim 3, wherein the acrylic monomer having a hydroxy group and the acrylic monomer having a carboxyl group have a total content of 9 to 45% by weight based on the total weight of the monomers.
5. The adhesive composition according to claim 1, wherein the photopolymerizable compound further comprises a polyfunctional acrylic monomer or a styrene monomer containing no hydroxy group.
6. The adhesive composition according to claim 5, wherein the polyfunctional acrylic monomer or the styrene monomer not containing a hydroxyl group is included in an amount of 0.1 to 5% by weight based on the total weight of the monomers.
7. The adhesive composition of claim 1, wherein the photopolymerization initiator is a radical photopolymerization initiator including at least one selected from the group consisting of acetophenone series, benzophenone series, thioxanthone series, benzoin series and benzoin alkyl ether series.
8. 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 7.
9. The composite polarizing plate according to claim 8, wherein the polarizer is a laminate having a film having a function of a protective film or a retardation film bonded to a surface opposite to the surface to be bonded to the patterned retardation layer.
10. The composite polarizing plate according to claim 8, wherein the patterned retardation layer comprises a liquid crystal coating layer containing a reactive liquid crystal monomer comprising a benzene ring.
11. The composite polarizing plate according to claim 8, wherein the peeling force between the polarizer and the patterned retardation layer is 1.0 N / 25 mm or more.
12. The composite polarizing plate according to claim 8, wherein the patterned retardation layer does not include an alignment film.
13. An image display device comprising the composite polarizing plate of claim 8.