# US 8,772,425 B2 · High refractive index pressure-sensitive adhesives

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- Number: US 8,772,425 B2
- Document ID: US8772425B2
- Status: Granted
- Kind: B2
- Application number: 13/742,022
- Filed: 2013-01-15
- Published: 2013-08-01
- Granted: 2014-07-08
- Earliest claimed: 2007-10-19
- Assignees: 3M Innovative Properties Company
- Applicants: 3M Innovative Properties Company
- Inventors: Michael D. Determan; Albert I. Evaraerts; Cheryl L. Moore; David B. Olson
- Web page: https://patentgrep.com/patent/US8772425B2

## CPC

- C09J 133/14: of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
- C09J 7/385: {Acrylic polymers}
- C09J 133/08: Homopolymers or copolymers of acrylic acid esters
- C09J 2301/302: the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
- Y10T 428/269: including synthetic resin or polymer layer or component
- Y10T 428/2848: Three or more layers
- Y10T 428/2891: including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention provides pressure-sensitive adhesives having a refractive index of at least 1.50. The pressure-sensitive adhesives comprise at least one monomer containing a substituted or an unsubstituted biphenyl group.

## Claims

### Claim 1

An adhesive article comprising:
a flexible or inflexible substrate; and
a pressure sensitive adhesive coated on the substrate, the pressure sensitive adhesive comprising: a random copolymer having:
a) 10 to 90 parts by weight of monomer units having pendent biphenyl groups;
b) 90 to 10 parts by weight of alkyl (meth)acrylate monomer units;
c) 1 to 15 parts by weight of acid functional monomer units;
d) 0 to 15 parts by weight of polar monomers; and
e) 0 to 5 parts by weight of other monomers,
wherein the sum of the monomers is 100 parts by weight; and
optionally a plasticizer, wherein the monomer units having pendent biphenyl groups are of the formula:
wherein
X1 and X2 are each independently —O—, —S—, or —NR3—, where R3 is H or C1-C4 alkyl;
R1 is an alkylene of 1 to 8 carbons optionally containing one or more catenary ether oxygen atoms or pendent hydroxy groups;
n is 0 or 1; and
R2 is either H or CH3; such that when n is 0, the biphenyl group comprises 2-substituted biphenyl, and wherein the monomer units having pendent biphenyl groups have as homopolymers a glass transition temperature of 70° C. or less.

### Claim 2 (depends on 1)

The adhesive article of claim 1, wherein the substrate comprises a flexible substrate comprising a plastic film.

### Claim 3 (depends on 2)

The adhesive article of claim 2, wherein the plastic film comprises a polypropylene film, a polyethylene film, a polyvinyl chloride film, a polyester film, a polycarbonate film, a polymethyl(meth)acrylate film, a cellulose acetate film, a cellulose triacetate film, or an ethyl cellulose film.

### Claim 4 (depends on 1)

The adhesive article of claim 1, wherein the substrate comprises an inflexible substrate comprising metal, metallized polymeric film, tin oxide coated glass, tin oxide coated polyester, polymethyl(meth)acrylate plate, polycarbonate plate, glass, or a ceramic sheet.

### Claim 5 (depends on 1)

The adhesive article of claim 1, wherein the coated pressure sensitive adhesive has a thickness of from 2-500 micrometers dry thickness.

### Claim 6 (depends on 1)

The adhesive article of claim 1, wherein the coated pressure sensitive adhesive has a thickness of from 25-250 micrometers dry thickness.

### Claim 7 (depends on 1)

The adhesive article of claim 1, wherein the pressure sensitive adhesive further comprises at least one additive.

### Claim 8 (depends on 7)

The adhesive article of claim 7, wherein the additive comprises a UV absorber, a hindered amine light stabilizer, or a combination thereof.

### Claim 9 (depends on 7)

The adhesive article of claim 7, wherein the additive comprises a UV absorber, wherein the UV absorber is present in an amount of 1 to 5 weight % based on the total weight of the pressure sensitive adhesive composition.

### Claim 10

A pressure sensitive adhesive comprising a random copolymer having:
a) 10 to 90 parts by weight of monomer units having pendent biphenyl groups;
b) 90 to 10 parts by weight of alkyl (meth)acrylate monomer units;
c) 1 to 15 parts by weight of acid functional monomer units;
d) 0 to 15 parts by weight of polar monomers; and
e) 0 to 5 parts by weight of other monomers,
wherein the sum of the monomers is 100 parts by weight; and
optionally a plasticizer, wherein the monomer units having pendent biphenyl groups are of the formula:
wherein
X1 and X2 are each independently —O—, —S—, or —NR3—, where R3 is H or C1-C4 alkyl;
R1 is an alkylene of 1 to 8 carbons optionally containing one or more catenary ether oxygen atoms or pendent hydroxy groups;
n is 0 or 1; and
R2 is either H or CH3; such that when n is 0, the biphenyl group comprises 2-substituted biphenyl, and wherein the monomer units having pendent biphenyl groups have as homopolymers a glass transition temperature of 70° C. or less;
and further comprising at least one additive.

### Claim 11 (depends on 10)

The pressure sensitive adhesive of claim 10, wherein the additive comprises a UV absorber, a hindered amine light stabilizer, or a combination thereof.

### Claim 12 (depends on 10)

The pressure sensitive adhesive of claim 10, wherein the additive comprises a UV absorber, wherein the UV absorber is present in an amount of 1 to 5 weight % based on the total weight of the pressure sensitive adhesive composition.