Adhesive composition

1. A process for preparing a melt-processible adhesive comprising:

a) dissolving a high T g copolymer having a Mw>30 kD comprising:

i) up to 100 parts by weight of high T g (meth)acrylic acid ester monomer units;

ii) 1 to 10 parts by weight of acid functional ethylenically unsaturated monomer units;

iii) 0 to 50 parts by weight of optional low T g (meth)acrylic acid ester monomer units;

iv) 1 to 10 parts by weight of non-acid functional, ethylenically unsaturated polar monomer units;

v) 0 to 5 parts by weight of vinyl monomer units;

wherein the sum of i) to v) is 100 parts by weight; and

wherein monomer units i) to v) are distinct monomer units;

in a monomer mixture for a low T g copolymer comprising

i. 85 to 99.5 parts by weight of low T g (meth)acrylic acid ester monomers;

ii. 0.5 to 15 parts by weight of acid functional ethylenically unsaturated monomers;

iii. 1 to 10 parts by weight of non-acid functional, ethylenically unsaturated polar monomers;

iv. 0 to 5 parts of vinyl monomers; wherein the sum of i) to iv) is 100 parts by weight; and

wherein monomer units i) to iv) are distinct monomer units;

said mixture optionally including a hydrogenated hydrocarbon tackifier;

b) polymerizing the resultant mixture;

c) adding hydrogenated hydrocarbon tackifier if not present in step a);

d) melt extruding the polymerized mixture to form an extrudate; and

e) crosslinking the extrudate by electron beam irradiation;

wherein the adhesive comprises a minimum of 0.05 moles of acid/base pairs per kilogram of the composition and comprising 0.1 to 20 parts by weight of a hydrogenated hydrocarbon tackifier, based on 100 parts by weight of the low T g monomer mixture and high T g copolymer.

2. The process of claim 1 , step a), comprising up to 40 parts by weight of the high T g copolymer and 60 parts by weight or greater of a low T g monomer mixture based on 100 parts by weight of the low T g monomer mixture and the high T g copolymer.

3. The process of claim 1 , step a), wherein the non-acid functional, ethylenically unsaturated polar monomers of the high T g copolymer are base-functional monomers, and the molar amount thereof is less than the molar amount of the acid-functional monomer.

4. An electron-beam crosslinked adhesive composition comprising:

a) a high T g copolymer having a Mw>30 kD comprising:

i) up to 100 parts by weight of high T g (meth)acrylic acid ester monomer units;

ii) 1 to 10 parts by weight of acid functional ethylenically unsaturated monomer units;

iii) 0 to 50 parts by weight of optional low T g (meth)acrylic acid ester monomer units;

iv) 1 to 10 parts by weight of non-acid functional, ethylenically unsaturated polar monomer units;

v) 0 to 5 parts by weight of vinyl monomer units;

wherein the sum of i) to v) is 100 parts by weight; and

wherein monomer units i) to v) are distinct monomer units;

b) a low T g copolymer comprising

i. 85 to 99.5 parts by weight of low T g (meth)acrylic acid ester monomers;

ii. 0.5 to 15 parts by weight of acid functional ethylenically unsaturated monomers;

iii. 1 to 10 parts by weight of non-acid functional, ethylenically unsaturated polar monomers;

iv. 0 to 5 parts of vinyl monomers; wherein the sum of i) to iv) is 100 parts by weight; and

wherein monomer units i) to iv) are distinct monomer units; and

c) 0.1 to 20 parts by weight of a hydrogenated hydrocarbon tackifier, based on 100 parts by weight of the low T g monomer mixture and high T g copolymer a hydrogenated hydrocarbon tackifier;

wherein the adhesive comprises a minimum of 0.05 moles of acid/base pairs per kilogram of the composition.

5. The adhesive composition of claim 4 containing no crosslinking agents.