Pressure-sensitive adhesive sheet for surface protection

Patent metadata

Field	Value
Publication number	US-8962136-B2
Application number	US-201013502146-A
Country	US
Kind code	B2
Filing date	Oct 20, 2010
Priority date	Oct 20, 2009
Publication date	Feb 24, 2015
Grant date	Feb 24, 2015

Abstract

A surface-protecting pressure-sensitive adhesive sheet includes: a substrate; and a pressure-sensitive adhesive layer that is provided on at least one side of the substrate and made from a polyester-based pressure-sensitive adhesive composition containing a crosslinking agent and a polyester including at least a lactic acid unit, a dibasic acid unit, and a glycol unit. The dibasic acid unit includes a dimer acid, the polyester has a weight average molecular weight of 20,000 to 200,000 and a glass transition temperature of −70 to −20° C. as measured using a differential scanning calorimeter at a temperature rise rate of 20° C./minute, the polyester-based pressure-sensitive adhesive composition has a hydroxyl value of 20 to 60 mgKOH/g, and the pressure-sensitive adhesive layer has a gel fraction of 85 to 99% by weight.

First claim

The invention claimed is:

1. A surface-protecting pressure-sensitive adhesive sheet, comprising:
a substrate; and
a pressure-sensitive adhesive layer that is provided on at least one side of the substrate and made from a polyester-based pressure-sensitive adhesive composition comprising a crosslinking agent and a polyester comprising at least a lactic acid unit, a dibasic acid unit, and a glycol unit, wherein
the dibasic acid unit comprises a dimer acid,
the polyester has a weight average molecular weight of 20,000 to 200,000 and a glass transition temperature of −70 to −20° C. as measured using a differential scanning calorimeter at a temperature rise rate of 20° C./minute,
the polyester-based pressure-sensitive adhesive composition has a hydroxyl value of 20 to 60 mgKOH/g,
the pressure-sensitive adhesive layer has a gel fraction of 85 to 99% by weight, and
the pressure-sensitive adhesive layer has a storage modulus of 1×10 4 to 1×10 7 Pa as measured using a dynamic viscoelasticity meter under the conditions of 23° C. and a frequency of 1 Hz.

2. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the polyester contains 10 to 50% by mole of the lactic acid unit and 50 to 90% by mole of the components other than the lactic acid unit, and the molar ratio of the dibasic acid unit to the glycol unit is 1:0.8 to 1:1.2.

3. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the dibasic acid unit further comprises an aliphatic dibasic acid other than the dimer acid.

4. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the polyester comprises a tri- or polyfunctional carboxylic acid and/or polyol component as a component other than the lactic acid unit, the dibasic acid unit, and the glycol unit, and the polyester has a dispersity (Mw/Mn) of 2.5 to 10.0.

5. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the polyester has a hydroxyl value of 2 to 50 mgKOH/g.

6. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the polyester-based pressure-sensitive adhesive composition further comprises a branched polyester oligomer with a hydroxyl value of 100 to 1,000 mgKOH/g, and the composition comprises 50 to 99 parts by weight of the polyester and 1 to 50 parts by weight of the branched polyester oligomer.

7. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the crosslinking agent is a polyvalent isocyanurate.

8. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , which has an initial adhesive strength of 0.1 to 0.5 N/20 mm at 23° C., a peel angle of 180° with respect to an acrylic plate, and a rate of pulling of 300 mm/minute, and has an adhesive strength of 0.1 to 1.0 N/20 mm after storage at 40° C. for 30 days.

9. The surface-protecting pressure-sensitive adhesive sheet according to claim 1 , wherein the substrate is biodegradable.

Assignees

• Takahira Hitoshi
• Yoshie Satomi
• Nitto Denko Corp

Inventors

• Takahira Hitoshi
• Yoshie Satomi

Classifications

• C08G63/60

  derived from the reaction of a mixture of hydroxy carboxylic acids, polycarboxylic acids and polyhydroxy compounds · CPC title

• C09J2467/00

  Presence of polyester · CPC title

• C09J7/0246

  Chemistry & Metallurgy · mapped topic

• C08G18/4202

  Two or more polyesters of different physical or chemical nature (C08G18/44 takes precedence) · CPC title

• C08G18/428

  Lactides · CPC title