(Meth)acrylic adhesive composition, its method of preparation and its use

1. A method for manufacturing a polymer composition suitable as (meth)acrylic adhesive composition comprising the steps of:

(a) providing a first part composition (P1) comprising,

a1) at least one (meth)acrylic monomer (M1),

a2) a multistage polymer (MP1) having a core-shell structure,

a3) a polymer (C1);

(b) providing a second part composition (P2) comprising,

b1) a polymerization initiator,

(c) polymerizing the mixture of (P1) and (P2),

wherein polymer (C1) has a mass average molecular weight Mw between 100,000 g/mol and 1,000,000 g/mol;

wherein said multistage polymer (MP1) having said core-shell structure and a3) the polymer (C1) of the first part composition (P1) form together a polymer composition (PC1) and are made by a method comprising the steps of:

a) polymerizing by emulsion polymerization of a monomer or monomer mixture (A m ) to obtain one layer in stage (A) comprising polymer (A1) having a glass transition temperature of less than 10° C.,

b) polymerizing by emulsion polymerization of a monomer or monomer mixture (B m ) to obtain layer in stage (B) comprising a polymer (B1) having a glass transition temperature of at least 60° C.,

c) polymerizing by emulsion polymerization of a monomer or monomer mixture (Cm) to obtain a layer in stage (C) comprising a polymer (C1) having a glass transition temperature of at least 30° C.,

wherein component c) represents at most 30 wt %.

2. The method according to claim 1 , wherein polymer (C1) has a mass average molecular weight Mw between 105,000 g/mol and 900,000 g/mol.

3. The method according to claim 1 , wherein polymer (C1) has a mass average molecular weight Mw between 140,000 g/mol and 500,000 g/mol.

4. The method according to claim 1 wherein the ratio r of the polymer (C1) in a composition comprising only the multistage polymer (MP1) and the polymer (C1) is less than 30 wt %.

5. The method according to claim 1 wherein the ratio r of the polymer (C1) in a composition comprising only the multistage polymer (MP1) and the polymer (C1) is at least 5 wt %.

6. The method according to claim 1 wherein the ratio r of the polymer (C1) in a composition comprising only the multistage polymer (MP1) and the polymer (C1) is between 5 wt % and less than 25 wt %.

7. The method according to claim 1 wherein the first part composition (P1) comprises one more additional compound: at least one monomer (M2) different from (meth)acrylic monomer (M1).

8. The method according to claim 7 wherein (meth)acrylic monomer (M2) is chosen from acrylic ester monomers or methacrylic ester monomers that have at least one atom that is not a carbon or hydrogen in the group of the alcohol part of the ester.

9. The method according to claim 7 wherein (meth)acrylic monomer (M2) is chosen from the group consisting of: 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2- and 3-hydroxypropyl acrylate, 2- and 3-hydroxypropyl methacrylate, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl acrylate, 2-ethoxyethyl methacrylate, 2- or 3-ethoxypropyl acrylate, 2- or 3-ethoxypropyl methacrylate, 2(2-ethoxyethoxy) ethyl acrylate, methoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, polyethylene glycol methacrylate, polyethylene glycol acrylate, polypropylene glycol methacrylate, polypropylene glycol acrylate, and mixtures thereof.

10. The method according to claim 1 wherein first part composition (P1) comprises one more additional compound: a flexibilizer.

11. The method according to claim 10 wherein the flexibilizer is chosen from a block copolymer or a liquid elastomer.

12. The method according to claim 10 wherein the flexibilizer is chosen from urethanes oligomers.

13. The method according to claim 1 wherein polymer (C1) is a (meth) acrylic polymer.