# US 9,434,866 B2 · Adhesives comprising epoxy-acid crosslinked groups and methods

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- Number: US 9,434,866 B2
- Document ID: US9434866B2
- Status: Granted
- Kind: B2
- Application number: 14/194,840
- Filed: 2014-03-03
- Published: 2014-09-18
- Granted: 2016-09-06
- Earliest claimed: 2013-03-13
- Applicants: 3M Innovative Properties Company
- Inventors: Arlin L. Weikel; Babu N. Gaddam; Larry R. Krepski; Wayne S. Mahoney; Jason D. Clapper
- Web page: https://patentgrep.com/patent/US9434866B2

## CPC

- C09J 133/08: Homopolymers or copolymers of acrylic acid esters
- C08L 63/00: Compositions of epoxy resins; Compositions of derivatives of epoxy resins
- C09J 7/385: {Acrylic polymers}
- C09J 133/068: {containing glycidyl groups}
- C08L 2312/00: Crosslinking
- Y10T 428/2809: including irradiated or wave energy treated component
- 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)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Adhesives compositions and methods of preparing adhesive compositions are described. The methods generally comprise a) providing a syrup composition comprising i) a free-radically polymerizable solvent monomer; and ii) a solute (meth)acrylic copolymer; and b) radiation curing the syrup composition in the absence of an ionic photoacid generator. In one embodiment, the solute (meth)acrylic copolymer as provided or during curing comprises repeat units derived from at least one alkyl(meth)acrylate monomer, at least one ethylenically unsaturated monomer comprising an acid-functional group; and at least one (meth)acryloyl monomer comprising an epoxy-functional group; and the acid-functional groups crosslink with the epoxy-functional groups. In another embodiment, the solute (meth)acrylic copolymer comprising repeat units derived from at least one alkyl(meth)acrylate monomer and at least one ethylenically unsaturated monomer comprising an acid-functional group; and an epoxy resin, having on average greater than one polymerizable epoxy group per molecule, crosslinks the acid-functional groups.

## Claims

### Claim 1

A method of preparing an adhesive composition comprising:
a) providing a syrup composition comprising
i) a free-radically polymerizable solvent monomer;
ii) a solute (meth)acrylic copolymer comprising repeat units derived from
at least one alkyl(meth)acrylate monomer, and
at least one ethylenically unsaturated monomer comprising an acid-functional group;
optionally at least one (meth)acryloyl monomer comprising an epoxy-functional group
iii) an epoxy resin having on average greater than one polymerizable epoxy group per molecule; and
b) radiation curing the syrup composition in the absence of an ionic photoacid generator and multifunctional(meth)acrylate monomer such that the epoxy resin crosslinks the acid-functional groups.

### Claim 2 (depends on 1)

The method of claim 1 wherein the syrup comprises 0.1 to 10 wt-% of ethylenically unsaturated monomer(s) comprising an acid-functional group.

### Claim 3 (depends on 1)

The method of claim 1 wherein the acid-functional group is a carboxylic acid group.

### Claim 4 (depends on 1)

The method of claim 1 wherein the ethylenically unsaturated monomer comprising an acid-functional group is acrylic acid or (meth)acrylic acid.

### Claim 5 (depends on 1)

The method of claim 1 wherein the (meth)acrylic copolymer comprises 0.1 to 5 wt-% of (meth)acryloyl monomer comprising an epoxy-functional group.

### Claim 6 (depends on 1)

The method of claim 1 wherein the (meth)acryloyl monomer comprising an epoxy-functional group is of the formula:
wherein:
R7 is —H or C1-C4 alkyl;
X1 is —NR9— or —O—; and
R8 is an epoxy-substituted (hetero)hydrocarbyl group.

### Claim 7 (depends on 1)

The method of claim 1 wherein the (meth)acryloyl monomer comprising an epoxy-functional group is of the formula:
wherein:
R10 is a (hetero)hydrocarbyl group, preferably a hydrocarbyl group;
R11 is —H or C1-C4 alkyl; and
X2 is —NR12— or —O—.

### Claim 8 (depends on 1)

The method of claim 1 wherein the syrup comprises at least 50 wt-% of (meth)acrylic acid ester monomers having a Tg less than 0° C.

### Claim 9 (depends on 1)

The method of claim 1 wherein the adhesive is a pressure sensitive adhesive.

### Claim 10 (depends on 1)

The method of claim 1 wherein the syrup comprises a photoinitiator.

### Claim 11 (depends on 1)

The method of claim 1 wherein the solute (meth)acrylic copolymer is prepared by copolymerizing the alkyl (meth)acrylate monomer, the ethylenically unsaturated monomer comprising an acid-functional group; and the monomer comprising an epoxy-functional group.

### Claim 12 (depends on 1)

The method of claim 1 wherein the solute (meth)acrylic copolymer is prepared by copolymerizing the alkyl (meth)acrylate monomer and the ethylenically unsaturated monomer comprising an acid-functional group; and the monomer comprising an epoxy-functional group is added prior to radiation curing.

### Claim 13 (depends on 1)

The method of claim 1 wherein the solute (meth)acrylic copolymer is prepared by copolymerizing the alkyl (meth)acrylate monomer and the monomer comprising an epoxy-functional group; and the ethylenically unsaturated monomer comprising an acid-functional group is added prior to radiation curing.

### Claim 14 (depends on 1)

The method of claim 1 wherein the radiation curing comprises exposing the syrup to ultraviolet radiation.

### Claim 15 (depends on 1)

The method of claim 1 wherein the syrup is applied to a substrate prior to radiation curing.

### Claim 16 (depends on 1)

The method of claim 1 wherein the adhesive composition comprises 0.5 to 3 wt-% of epoxy resin.

### Claim 17 (depends on 1)

The method of claim 1 wherein the acid-functional group of the solute (meth)acrylic copolymer directly ring opens the epoxy group forming a crosslink.