Optically clear adhesive, method of use and articles therefrom

Patent metadata

Field	Value
Publication number	US-9879161-B2
Application number	US-201213985602-A
Country	US
Kind code	B2
Filing date	Feb 17, 2012
Priority date	Feb 18, 2011
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

An adhesive composition includes an alkyl (meth)acrylate ester, wherein the alkyl group has 4 to 18 carbon atoms, a hydrophilic copolymerizable monomer and a free-radical generating initiator. The adhesive composition has a tan delta value of between about 0.5 and about 1.0 at a temperature of between about 25 C and about 100 C.

First claim

The invention claimed is:

1. An adhesive composition comprising:
a polymer made from a pre-mix comprising monomers comprising:
an alkyl (meth)acrylate ester, wherein the alkyl group has 4 to 18 carbon atoms, or an aryl (meth)acrylate ester, selected from 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, n-nonyl (meth)acrylate, isoamyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isostearyl acrylate, 2-methylbutyl (meth)acrylate, and combinations thereof; and
a hydrophilic copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, methacrylamide, N—(C1-C3)alkyl-substituted acryl amide, N—(C1-C3)alkyl-substituted methacrylamide, N,N-di(C1-C3)alkyl-substituted acrylamide, N,N-di(C1-C3)alkyl-substituted methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, acrylamide, N-morpholino acrylate, and combinations thereof; and

an acrylic oligomer made from monomers comprising (C1-C20)alkyl (meth)acrylate monomers, wherein the acrylic oligomer has a Tg below 25° C. and a weight average molecular weight of at least 1,000 and no more than the oligomer's entanglement molecular weight;
wherein the adhesive composition retains a tan delta value of between about 0.5 and about 1.0 over a temperature range of between about 25° C. and about 100° C. and a frequency of 1 Hz; and
wherein the adhesive composition is optically clear, having at least 85% transmission over the range of from 460 to 720 nm.

2. The adhesive composition of claim 1 , wherein the adhesive composition retains a tan delta value of between about 0.6 and about 0.8 over a temperature range of between about 25° C. and about 100° C. and a frequency of 1 Hz.

3. The adhesive composition of claim 1 , wherein the alkyl(meth)acrylate ester is selected from the group consisting of: 2-ethylhexyl acrylate (2-EHA), isobornyl acrylate (IBA), iso-octylacrylate (IOA) and butyl acrylate (BA).

4. The adhesive composition of claim 1 , wherein the hydrophilic copolymerizable monomer is selected from the group consisting of: acrylic acid (AA), 2-hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), ethoxyethoxyethyl acrylate, acrylic amide (Acm), N,N-dimethylacrylamide, and N-morpholino acrylate (MoA).

5. The adhesive composition of claim 1 , wherein the pre-mix further comprises a free-radical generating initiator.

6. The adhesive composition of claim 5 , wherein the pre-mix includes between about 0.05 parts and about 2 parts free-radical generating initiator.

7. The adhesive composition of claim 1 , wherein the pre-mix includes between about 5 parts and about 40 parts of the hydrophilic copolymerizable monomer.

8. The adhesive composition of claim 1 , wherein the pre-mix includes between about 60 parts and about 95 parts of the alkyl (meth)acrylate ester.

9. The adhesive composition of claim 1 , wherein the acrylic oligomer is made in-situ using a molecular weight control agent.

10. The adhesive composition of claim 1 , wherein the oligomer has a hydroxyl number of from about 20 mg KOH/g to about 500 mg KOH/g.

11. The adhesive composition of claim 1 , wherein the oligomer has a number average molecular weight of about 500 to about 10,000.

12. A laminate comprising:
a first substrate;
a second substrate; and
an adhesive composition positioned between the first and second substrates, wherein the adhesive composition comprises:
a polymer made from a pre-mix comprising monomers comprising:
an alkyl (meth)acrylate ester, wherein the alkyl group has 4 to 18 carbon atoms, or an aryl (meth)acrylate ester, selected from 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, n-nonyl (meth)acrylate, isoamyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isostearyl acrylate, 2-methylbutyl (meth)acrylate, and combinations thereof; and
a hydrophilic copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, methacrylamide, N—(C1-C3)alkyl-substituted acryl amide, N—(C1-C3)alkyl-substituted methacrylamide, N,N-di(C1-C3)alkyl-substituted acrylamide, N,N-di(C1-C3)alkyl-substituted methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, acrylamide, N-morpholino acrylate, and combinations thereof; and

an acrylic oligomer made from monomers comprising (C1-C20)alkyl (meth)acrylate monomers, wherein the acrylic oligomer has a Tg below 25° C. and a weight average molecular weight of at least 1,000 and no more than the oligomer's entanglement molecular weight;
wherein the adhesive composition retains a tan delta value of between about 0.5 and about 1.0 over a temperature range of between about 25° C. and about 100° C. and a frequency of 1 Hz; and
wherein the adhesive composition is optically clear, having at least 85% transmission over the range of from 460 to 720 nm.

13. The laminate of claim 12 , wherein at least one of the first and second substrates includes an ink step.

14. The laminate of claim 13 , wherein at least one of the first and second substrates includes an ink step of 50-70 μm, and wherein the adhesive thickness is no more than 250 μm.

15. The laminate of claim 12 , wherein the adhesive thickness is at least 150 μm.

16. The laminate of claim 12 , wherein at least one of the first and second substrates is substantially transparent.

17. The laminate of claim 12 , wherein the acrylic oligomer is made in-situ using a molecular weight control agent.

18. A method of assembling a laminate comprising:
providing an adhesive composition, wherein the adhesive composition comprises:
a polymer made from a pre-mix comprising monomers comprising:
an alkyl (meth)acrylate ester, wherein the alkyl group has 4 to 18 carbon atoms, or an aryl (meth)acrylate ester, selected from 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, n-nonyl (meth)acrylate, isoamyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isostearyl acrylate, 2-methylbutyl (meth)acrylate, and combinations thereof; and
a hydrophilic copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, methacrylamide, N—(C1-C3)alkyl-substituted acrylamide, N—(C1-C3)alkyl-substituted methacrylamide, N,N-di(C1-C3)alkyl-substituted acrylamide, N,N-di(C1-C3)alkyl-substituted methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, acrylamide, N-morpholino acrylate, and combinations thereof; and

an acrylic oligomer made from monomers comprising (C1-C20)alkyl (meth)acrylate monomers, wherein the acrylic oligomer has a Tg below 25° C. and a weigh

Assignees

• Xia Jianhui
• Everaerts Albert I
• 3M Innovative Properties Co

Inventors

• Xia Jianhui
• Everaerts Albert I

Classifications

• C09J133/08 Primary

  Homopolymers or copolymers of acrylic acid esters · CPC title

• B32B17/10743

  containing acrylate (co)polymers or salts thereof · CPC title

• B32B2307/412

  Transparent · CPC title

• C09J2203/318

  for the production of liquid crystal displays · CPC title

• C09J133/26

  Homopolymers or copolymers of acrylamide or methacrylamide · CPC title