Double-faced pressure-sensitive adhesive tape or sheet, and liquid crystal display apparatus

Abstract

The present invention relates to a double-faced pressure-sensitive adhesive tape or sheet, which comprises: a base material; a pressure-sensitive adhesive layer disposed on one surface of the base material, which is a pressure-sensitive adhesive layer (A) including a pressure-sensitive adhesive composition containing an acrylic polymer (A1), and a silicone rubber fine particle (A2) in a proportion of from 3 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer (A1), the layer (A) being used so as to adhere to the liquid crystal display module unit; and another pressure-sensitive adhesive layer disposed on the other surface of the base material, which is a pressure-sensitive adhesive layer (B) including a pressure-sensitive adhesive composition containing an acrylic polymer (B1), and a low-molecular weight polymer component (B2), which contains, as a principal monomer component, an ethylenic unsaturated monomer having a glass transition temperature of from 60 to 190° C. when it is formed into a homopolymer and having a cyclic structure within the molecule thereof, and which has a weight-average molecular weight equal to or higher than 3,000 but lower than 20,000, in a proportion of from 5 to 35 parts by weight with respect to 100 parts by weight of the acrylic polymer (B1), the layer (B) being used so as to adhere to the backlight, in which the pressure-sensitive adhesive tape or sheet is for use in fixing a liquid crystal display module unit and a backlight unit.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are schematic views illustrating a method for evaluating the repulsion resistance, used in evaluating the repulsion resistance of Examples, in which FIG. 1A is a schematic cross-sectional view illustrating a state where a member having a surface coating with a hard coat agent is adhered to a polyethylene terephthalate film; and FIG. 1B is a schematic cross-sectional view illustrating a state where the adhered members shown in FIG. 1A are adhered to a polycarbonate plate by a double-faced pressure-sensitive adhesive tape or sheet.

FIG. 2 is a schematic lateral view illustrating a method for evaluating the repulsion resistance, used in evaluating the repulsion resistance of Examples, in which the polyethylene terephthalate film is bent into a loop for evaluating the repulsion resistance.

FIGS. 3A, 3B and 3C are schematic views illustrating a method for evaluating the dropping impact resistance used in evaluating the dropping impact resistance of Examples, in which FIG. 3A is a schematic view illustrating a shape of a punched double-faced pressure-sensitive adhesive tape or sheet; FIG. 3B is a schematic plan view illustrating two polycarbonate plates adhered with a double-faced pressure-sensitive adhesive tape or sheet; and FIG. 3C is a schematic lateral view of FIG. 3B.

FIGS. 4A, 4B and 4C are schematic views illustrating the shape of a holder for fixing the two polycarbonate plates adhered by the double-faced pressure-sensitive adhesive tape or sheet for evaluating the dropping impact resistance, in which FIG. 4A is a schematic plan view, FIG. 4B is a schematic cross-sectional view along a line X-X in FIG. 4A, and FIG. 4C is a schematic cross-sectional view along a line Y-Y in FIG. 4A.

FIG. 5 is a schematic view illustrating a method for evaluating the dropping impact resistance, used in evaluating the dropping impact resistance of Examples, and illustrating a state where the holder, in which the two polycarbonate plates adhered by the double-faced pressure-sensitive adhesive tape or sheet are fixed, is dropped from a height of 1 m or 1.5 m.

Claims

1. A double-faced pressure-sensitive adhesive tape or sheet, which comprises: a base material;a pressure-sensitive adhesive layer disposed on one surface of the base material, which is a pressure-sensitive adhesive layer (A) including a pressure-sensitive adhesive composition containing:an acrylic polymer (A1), anda silicone rubber fine particle (A2) in a proportion of from 3 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer (A1),said layer (A) being used so as to adhere to the liquid crystal display module unit; andanother pressure-sensitive adhesive layer disposed on the other surface of the base material, which is a pressure-sensitive adhesive layer (B) including a pressure-sensitive adhesive composition containing:an acrylic polymer (B1), and

2. A double-faced pressure-sensitive adhesive tape or sheet having a light-reflective property and/or a light-shielding property, which comprises: a base material;a pressure-sensitive adhesive layer disposed on one surface of the base material, which is a pressure-sensitive adhesive layer (A) including a pressure-sensitive adhesive composition containing:an acrylic polymer (A1), and a silicone rubber fine particle (A2) in a proportion of from 3 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer (A1),said layer (A) being used so as to adhere to the liquid crystal display module unit; andanother pressure-sensitive adhesive layer disposed on the other surface of the base material, which is a pressure-sensitive adhesive layer (B) including a pressure-sensitive adhesive composition containing;an acrylic polymer (B1), anda low-molecular weight polymer component (B2), which contains, as a principal monomer component, an ethylenic unsaturated monomer having a glass transition temperature of from 60 to 190° C. when it is formed into a homopolymer an d having a cyclic structure within the molecule thereof, and which has a weight-average molecular weight equal to or higher than 3,000 but lower than 20,000, in a proportion of from 5 to 35 parts by weight with respect to 100 parts by weight of the acrylic polymer (B1),said layer (B) being used so as to adhere to the backlight,said pressure-sensitive adhesive tape or sheet having a reflectance of 60% or higher and/or a transmittance of 0.3% or lower on at least one surface thereof, andwherein said pressure-sensitive adhesive tape or sheet is for use in fixing a liquid crystal display module unit and a backlight unit.

3. The double-faced pressure-sensitive adhesive tape or sheet according to claim 1, wherein the pressure-sensitive adhesive layer (A) and/or the pressure-sensitive adhesive layer (B) has a gel fraction of from 51 to 70 wt %.

4. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, wherein the pressure-sensitive adhesive layer (A) and/or the pressure-sensitive adhesive layer (B) has a gel fraction of from 51 to 70 wt %.

5. The double-faced pressure-sensitive adhesive tape or sheet according to claim 1, wherein the acrylic polymer (A1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (A) is an acrylic polymer containing, as a principal monomer component, a (meth)acrylic acid alkyl ester having 6 to 12 carbon atoms in the alkyl group thereof, and, as a monomer component, a carboxyl group-containing monomer in a proportion of from 3 to 10 parts by weight with respect to 100 parts by weight of all the monomer components.

6. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, wherein the acrylic polymer (A1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (A) is an acrylic polymer containing, as a principal monomer component, a (meth)acrylic acid alkyl ester having 6 to 12 carbon atoms in the alkyl group thereof, and, as a monomer component, a carboxyl group-containing monomer in a proportion of from 3 to 10 parts by weight with respect to 100 parts by weight of all the monomer components.

7. The double-faced pressure-sensitive adhesive tape or sheet according to claims 1, wherein the acrylic polymer (A1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (A) has a weight-average molecular weight of from 700,000 to 2,000,000.

8. The double-faced pressure-sensitive adhesive tape or sheet according to claims 2, wherein the acrylic polymer (A1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (A) has a weight-average molecular weight of from 700,000 to 2,000,000.

9. The double-faced pressure-sensitive adhesive tape or sheet according to claim 1, wherein the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (B) further comprises a silicone rubber fine particle.

10. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, wherein the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (B) further comprises a silicone rubber fine particle.

11. The double-faced pressure-sensitive adhesive tape or sheet according to claim 1, wherein the acrylic polymer (B1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (B) is an acrylic polymer containing, as a principal monomer component, a (meth)acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group thereof, and, as a monomer component, a carboxyl group-containing monomer in a proportion of from 3 to 10 parts by weight with respect to 100 parts by weight of all the monomer components.

12. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, wherein the acrylic polymer (B1) in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (B) is an acrylic polymer containing, as a principal monomer component, a (meth)acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group thereof, and, as a monomer component, a carboxyl group-containing monomer in a proportion of from 3 to 10 parts by weight with respect to 100 parts by weight of all the monomer components.

13. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, which has a reflective layer for providing a reflectance of 60% or higher on at least one surface of said pressure-sensitive adhesive tape or sheet, said reflective layer being a white-colored layer having a white color or a silver-colored layer having a silver color, wherein the reflective layer is the base material, the pressure-sensitive adhesive layer, or an optional layer other than the base material and the pressure-sensitive adhesive layer.

14. The double-faced pressure-sensitive adhesive tape or sheet according to claim 2, which has a light-shielding layer for providing a transmittance of 0.3% or less, said light-shielding layer being a black-colored layer having a black color, wherein the reflective layer is the base material, the pressure-sensitive adhesive layer, or an optional layer other than the base material and the pressure-sensitive adhesive layer.

15. A liquid crystal display apparatus comprising: a liquid crystal display module unit,a backlight unit; andthe double-faced pressure-sensitive adhesive tape or sheet according to claim 1, which fixes the liquid crystal display module unit and the backlight unit.

16. A liquid crystal display apparatus comprising: a liquid crystal display module unit;a backlight unit; andthe double-faced pressure-sensitive adhesive tape or sheet according to claim 2, which fixes the liquid crystal display module unit and the backlight unit.

17. The liquid crystal display apparatus according to claim 15, wherein the backlight unit comprises a substrate formed by polycarbonate.

18. The liquid crystal display apparatus according to claim 16, wherein the backlight unit comprises a substrate formed by polycarbonate.