Adhesive for polarizing plate, polarizing plate, method for producing same, optical film, and image display device

Patent metadata

Field	Value
Publication number	US-9366900-B2
Application number	US-201113581916-A
Country	US
Kind code	B2
Filing date	Mar 3, 2011
Priority date	Mar 5, 2010
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

An object of the invention is to provide an adhesive for a polarizing plate that has high adhering strength, makes it possible to prevent a reduction in the light transmittance of a polarizing plate and to suppress the occurrence of knicks, and is less likely to cause a reduction in the light transmittance of a polarizing plate even in a humidified environment while having the above characteristics. The invention is directed to an adhesive for a polarizing plate for use in fixing a transparent protective film on at least one side of a polarizer, the adhesive including a resin solution containing a polyvinyl alcohol-based resin and a water-soluble silicate.

First claim

The invention claimed is:

1. A polarizing plate, comprising:
a polarizer;
an adhesive layer; and
a transparent protective film provided on at least one side of the polarizer with the adhesive layer interposed therebetween, wherein
the adhesive layer has a refractive index of 1.47 to 1.54, and is made from an adhesive comprising a resin solution containing a polyvinyl alcohol-based resin and at least one water-soluble silicate selected from the group consisting of water-soluble lithium silicate, water-soluble sodium silicate, and water-soluble potassium silicate,
wherein the water-soluble lithium silicate has a molar SiO 2 /Li 2 O ratio of 2 to 8,
wherein the water-soluble sodium silicate has a molar SiO 2 /Na 2 O ratio of 4 to 5,
and wherein the water-soluble potassium silicate has a molar SiO 2 /K 2 O ratio of 2 to 5.

2. A polarizing plate, comprising:
a polarizer;
an adhesive layer; and
a transparent protective film provided on at least one side of the polarizer with the adhesive layer interposed therebetween, wherein
the adhesive layer has a refractive index of 1.47 to 1.55, and is made from an adhesive comprising a resin solution containing a polyvinyl alcohol-based resin, at least one water-soluble silicate selected from the group consisting of water-soluble lithium silicate, water-soluble sodium silicate, and water-soluble potassium silicate, and an amino acid and/or a sulfur-containing amino acid, having at least one amino group and at least one acidic group,
wherein the water-soluble lithium silicate has a molar SiO 2 /Li 2 O ratio of 2 to 8,
wherein the water-soluble sodium silicate has a molar SiO 2 /Na 2 O ratio of 4 to 5,
and wherein the water-soluble potassium silicate has a molar SiO 2 /K 2 O ratio of 2 to 5.

3. The polarizing plate according to claim 1 , wherein the content of the water-soluble silicate is from 1 to 100 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin.

4. The polarizing plate according to claim 2 , wherein the content of the amino acid and/or the sulfur-containing amino acid is from 5 to 50 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin.

5. The adhesive for a polarizing plate according to claim 2 , wherein the acidic group is a carboxyl group or a sulfo group.

6. The polarizing plate according to claim 1 or 2 , wherein the polyvinyl alcohol-based resin is a polyvinyl alcohol-based resin containing an acetoacetyl group.

7. The polarizing plate according to claim 1 or 2 , wherein the adhesive layer has a thickness of 10 nm to 300 nm.

8. An optical film, comprising a laminate comprising at least one piece of the polarizing plate according to claim 1 or 2 .

9. An image display device, comprising the optical film according to claim 8 .

10. An image display device, comprising the polarizing plate according to claim 1 or 2 .

11. A method for manufacturing a polarizing plate comprising a polarizer and a transparent protective film provided on at least one side of the polarizer with an adhesive layer interposed therebetween, the method comprising the steps of:
preparing an adhesive;
applying the adhesive to a surface of the polarizer, on which the adhesive layer is to be formed, and/or a surface of the transparent protective film, on which the adhesive layer is to be formed; and
bonding the polarizer and the transparent protective film together,
wherein the adhesive comprises a resin solution containing a polyvinyl alcohol-based resin and at least one water-soluble silicate selected from the group consisting of water-soluble lithium silicate, water-soluble sodium silicate, and water-soluble potassium silicate,
wherein the water-soluble lithium silicate has a molar SiO 2 /Li 2 O ratio of 2 to 8,
wherein the water-soluble sodium silicate has a molar SiO 2 /Na 2 O ratio of 4 to 5,
wherein the water-soluble potassium silicate has a molar SiO 2 /K 2 O ratio of 2 to 5,
and wherein the formed adhesive layer has a refractive index of 1.47 to 1.54;
or, wherein the adhesive comprises a resin solution containing a polyvinyl alcohol based resin, at least one water-soluble silicate selected from the group consisting of water-soluble lithium silicate, water-soluble sodium silicate, and water-soluble potassium silicate, and an amino acid and/or a sulfur-containing amino acid, having at least one amino group and at least one acidic group,
wherein the water-soluble lithium silicate has a molar SiO 2 /Li 2 O ratio of 2 to 8,
wherein the water-soluble sodium silicate has a molar SiO 2 /Na 2 O ratio of 4 to 5,
wherein the water-soluble potassium silicate has a molar SiO 2 /K 2 O ratio of 2 to 5,
and wherein the formed adhesive layer has a refractive index of 1.47 to 1.55.

Assignees

• Akari Reiko
• Ikeda Tetsurou
• Shinagawa Masashi
• Asahara Yoshifumi
• Nitto Denko Corp

Inventors

• Akari Reiko
• Ikeda Tetsurou
• Shinagawa Masashi
• Asahara Yoshifumi

Classifications

• Y10T428/1059

  Cross-Sectional Technologies · mapped topic

• G02F2202/28

  Adhesive materials or arrangements · CPC title

• C08K5/175

  containing COOH-groups; Esters or salts thereof · CPC title

• Y10T428/1041

  Cross-Sectional Technologies · mapped topic

• G02F1/133528 Primary

  Polarisers · CPC title