(Meth)acrylate block copolymer pressure sensitive adhesives

• US 7,255,920 B2
• Filed: 07/29/2004
• Issued: 08/14/2007
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Everaerts, Albert I., Xia, Jianhui, Lu, Ying-Yuh, Nguyen, Lang N.
• Primary Examiner(s): Kruer; Kevin R.
• Application Number:
  US10/901,629
• Publication Number:
  US 20060024521A1
• Time in Patent Office: 1,111 Days
• Field of Search: 525/244, 525/299, 524/558, 428/500, 428/522, 428/412, 428/520, 428/355.AC
• US Class Current: 428/355.0AC
• CPC Class Codes: B32B 2255/10 on synthetic resin layer or on natural or synthetic rubber layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/748 Releasability
• CPC Class Codes: B32B 2405/00 Adhesive articles, e.g. adhesive tapes
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/365 comprising polycarbonates
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08F 293/005 using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: C09J 153/00 Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
• CPC Class Codes: C09J 2301/414 presence of a copolymer
• CPC Class Codes: C09J 2433/00 Presence of (meth)acrylic polymer
• CPC Class Codes: C09J 2453/00 Presence of block copolymer
• CPC Class Codes: C09J 7/22 Plastics; Metallised plastics
• CPC Class Codes: C09J 7/38 Pressure-sensitive adhesives [PSA]
• CPC Class Codes: C09J 7/387 : Block-copolymers
• CPC Class Codes: G02B 1/04 : made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02F 2202/28 : Adhesive materials or arrangements
• CPC Class Codes: Y10T 428/1476 : Release layer
• CPC Class Codes: Y10T 428/254 : Polymeric or resinous material
• CPC Class Codes: Y10T 428/2891 : including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof
• CPC Class Codes: Y10T 428/31507 : Of polycarbonate
• CPC Class Codes: Y10T 428/31928 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31935 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31938 : Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Articles are provided that include an optical film and an optically clear pressure sensitive adhesive layer on at least one outer surface of the optical film. Additionally, articles are provided that include a pressure sensitive adhesive layer that resists bubble formation when adhered to an outgassing substrate. The pressure sensitive adhesive layer in the various articles contain a (meth)acrylate block copolymer.

Claims

1. An article comprising:

a) an optical film having a first major outer surface and a second major outer surface opposite the first major outer surface;

b) a substrate; and

c) an optically clear pressure sensitive adhesive layer positioned between said first major outer surface of the optical film and the substrate, said pressure sensitive adhesive layer being free of birefringence and consisting essentially of a (meth)acrylate block copolymer comprising

i. at least two A block polymeric units that are the reaction product of a first monomer composition comprising an alkyl methacrylate, an aralkyl methacrylate, an aryl methacrylate, or a combination thereof, each A block having a Tg of at least 50°

C., said (meth)acrylate block copolymer comprising 20 to 50 weight percent A block; and

ii. at least one B block polymeric unit that is the reaction product of a second monomer composition comprising an alkyl(meth)acrylate, a heteroalkyl(meth)acrylate, a vinyl ester, or a combination thereof said B block having a Tg no greater than 20°

C., said (meth)acrylaie block copolymer comprising 50 to 80 weight percent B block,

wherein the A block polymeric units are present as nanodomains having an average size less than about 150 nanometers in a matrix of the B block polymeric units.

2. The article of claim 1, wherein the first monomer composition comprises methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, or a combination thereof.

3. The article of claim 1, wherein the A block polymeric units have a Tg of at least 100°

C. and the B block polymeric unit has a Tg no greater than 0°

C.

4. The article of claim 1, wherein the A block comprises poly(methyl methacrylate).

5. The article of claim 1, wherein the second monomer composition comprises an alkyl(meth)acrylate with the alkyl group having 4 to 18 carbon atoms.

6. The article of claim 5, wherein the second monomer composition comprises n-butyl acrylate.

7. The article of claim 1, wherein the A block has an average molecular weight of at least 5,000 g/mole and the B block has an average molecular weight of at least 30,000 g/mole.

8. The article of claim 1, wherein the (meth)acrylate block copolymer is a triblock copolymer or a starblock copolymer with the A blocks being endblocks.

9. The article of claim 1, wherein the (meth)acrylate block copolymer has a storage modulus G′

where 5.1 Pa<

log(G′

) at 25°

C. and 4.4 Pa<

log(G′

) at 150°

C.

10. The article of claim 1, wherein the substrate comprises an outgassing layer selected from a polycarbonate or poly(meth)acrylate.

11. The article of claim 1, wherein the substrate is a release liner.

12. An article comprising:

a) an optical film having a first major outer surface and a second major outer surface opposite the first major outer surface; and

b) a first optically clear pressure sensitive adhesive adjacent to the first major outer surface of said optical film, said first optically clear pressure sensitive adhesive being free of birefringence and consisting essentially of a (meth)acrylate block copolymer comprising

i. at least two A block polymeric units that are the reaction product of a first monomer composition comprising an alkyl methacrylate, an aralkyl methacrylate, an aryl methacrylate, or a combination thereof, each A block having a Tg of at least 50°

C., said (meth)acrylate block copolymer comprising 20 to 50 weight percent A block; and

ii. at least one B block polymeric unit that is the reaction product of a second monomer composition comprising an alkyl(meth)acrylate, a heteroalkyl(meth)acrylate, a vinyl ester, or a combination thereof, said B block having a Tg no greater than 20°

C., said (meth)acrylate block copolymer comprising 50 to 80 weight percent B block; and

c) a second adhesive adjacent to the second major outer surface of the optical film, wherein the A block polymeric units are present as nanodomains having an average size less than about 150 nanometers in a matrix of the B block polymeric units.

13. The article of claim 12, wherein the second adhesive is an optically clear pressure sensitive adhesive.

14. The article of claim 12, further comprising a substrate attached to an outer surface of at least one of the first optically clear pressure sensitive adhesive or the second adhesive.

15. The article of claim 14, wherein the substrate is a release liner.

16. An article comprising:

a first substrate and a second substrate, wherein at least one of the first substrate or the second substrate is an outgassing substrate; and

a pressure sensitive adhesive layer positioned between the first substrate and the second substrate, said pressure sensitive adhesive layer being free of birefringence and comprising a (meth)acrylate block copolymer comprising

i. at least two A block polymeric units that are the reaction product of a first monomer composition comprising an alkyl methacrylate, an aralkyl methacrylate, an aryl methacrylate, or a combination thereof, each A block having a Tg of at least 50°

C., said (meth)acrylate block copolymer comprising 20 to 50 weight percent A block; and

ii. at least one B block polymeric unit that is the reaction product of a second monomer composition comprising an alkyl(meth)acrylate, a heteroalkyl(meth)acrylate, a vinyl ester, or a combination thereof, said B block having a Tg no greater than 20°

C., said (meth)acrylate block copolymer comprising 50 to 80 weight percent B block,

wherein the A block polymeric units are present as nanodomains having an average size less than about 150 nanometers in a matrix of the B block polymeric units, said block copolymer having a storage modulus G′

that varies as a function of temperature, wherein 5.1 Pa<

log(G′

) at 25°

C. and 4.4 Pa<

log(G′

) at 150°

C.

17. The article of claim 16, wherein the first substrate is an outgassing substrate comprising polycarbonate or poly(methyl methacrylate).