Acrylic resin powder, resin composition, hot melt adhesive composition containing acrylic resin powder and method for producing same

Patent metadata

Field	Value
Publication number	US-11939413-B2
Application number	US-202017031988-A
Country	US
Kind code	B2
Filing date	Sep 25, 2020
Priority date	Mar 26, 2018
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

An acrylic resin powder soluble in acetone, including a multi-stage polymer (M) that includes a polymer (B) obtained by polymerizing a monomer mixture (b) containing methyl methacrylate and an alkyl (meth)acrylate ester (mb) in the presence of a polymer dispersion that contains a polymer (A) obtained by polymerizing a monomer mixture (a) containing an alkyl (meth)acrylate ester (ma), in which an alkyl group in the alkyl (meth)acrylate ester (ma) has 4 to 8 carbon atoms, an alkyl group in the alkyl (meth)acrylate ester (mb) has 4 to 8 carbon atoms, a glass transition temperature of the polymer (A) is 20° C. or lower, a glass transition temperature of the polymer (B) obtained by polymerizing the monomer mixture (b) is 55° C. or higher, and a mass average molecular weight of the multi-stage polymer (M) is 10,000 or more and 300,000 or less.

First claim

The invention claimed is:

1. An acrylic resin powder, comprising:
a multi-stage polymer (M) comprising:
a polymer (B) obtained by polymerizing a monomer mixture (b) in the presence of a polymer dispersion of a polymer (A) obtained by polymerizing a monomer mixture (a) containing 50% to 60% by mass of methyl methacrylate and an alkyl (meth)acrylate ester (ma);
wherein
the monomer mixture (b) comprises:
50% to 90% by mass of methyl methacrylate,
10% to 50% by mass of an alkyl (meth)acrylate ester (mb), and
0% to 10% by mass of a copolymerizable monomer different from methyl methacrylate and the alkyl (meth)acrylate ester (mb),
the alkyl group of the alkyl (meth)acrylate ester (ma) has 4 to 8 carbon atoms,
the alkyl group of the alkyl (meth)acrylate ester (mb) bas 4 to 8 carbon atoms,
a glass transition temperature of the polymer (A) is 20° C. or lower,
a glass transition temperature of the polymer (B) is 55° C. or higher,
the acrylic resin powder is soluble in acetone, and
a mass average molecular weight of the multi-stage polymer (M) is 10,000 or more and 300,000 or less.

2. The acrylic resin powder according to claim 1 , wherein a volume average particle diameter of a primary particle of the multistage polymer (M) is from 0.1 μm to 10 μm.

3. The acrylic resin powder according to claim 1 , wherein a volume average particle diameter of secondary particles of the multistage polymer (M) is from 20 μm to 100 μm.

4. The acrylic resin powder according to claim 1 , wherein the monomer mixture (a) comprises with respect to a total mass of the monomer mixture (a);
from 50% to 60% by mass of methyl methacrylate; greater than 40% by mass of the alkyl (meth)acrylate ester (ma), and from 0% to 10% by mass of a copolymerizable monomer different from methyl methacrylate and the alkyl (meth)acrylate ester (ma) of.

5. The acrylic resin powder according to claim 1 wherein the polymer (A) is 10% to 80% by mass in a case where a total amount of polymers constituting the multi-stage polymer (M) is set to 100% by mass.

6. A method for producing the acrylic resin powder according to claim 1 , comprising:
performing polymerization to form a polymer (B) by dropwise adding a monomer mixture (b) to a polymer dispersion (Al) that contains a polymer (A) obtained by polymerizing a monomer mixture (a) containing 50% to 60% by mass of methyl methacrylate and an alkyl (meth)acrylate ester (ma) and a chain transfer agent of 0.1 to 3 parts by mass with respect to 100 parts by mass of the monomer mixture (a), to obtain a polymer dispersion (M1) that contains the multi-stage polymer (M) that includes the polymer (A) and the polymer (B); and
spray-drying the polymer dispersion (M1) containing the multi-stage polymer (M) to obtain an acrylic resin powder,
wherein
the monomer mixture (h) comprises:
50% to 90% by mass of methyl methacrylate
10% to 50% by mass of an alkyl (meth)acrylate ester (mb),
0% to 10% by mass of a copolymerizable monomer different from methyl methacrylate and the alkyl (meth)acrylate ester (mh), and
a chain transfer agent of 0.1 to 3 parts b mass with respect to 100 parts by mass of the monomer mixture (b),
the alkyl group of the alkyl (meth)acrylate ester (ma) has 4 to 8 carbon atoms, and
the alkyl group of the alkyl (meth)acrylate ester (mb) has 4 to 8 carbon atoms.

7. The method for producing the acrylic resin powder according to claim 6 , wherein the monomer mixture (a) comprises with respect to a total mass of the monomer mixture (a):
from 50% to 60% by mass of methyl methacrylate; greater than 40% by mass of the alkyl (meth)acrylate ester (ma); and
from 0% to 10% by mass of a copolymerizable monomer different from methyl methacrylate and the alkyl (meth)ylate ester (ma).

8. The r ethod for producing the acrylic resin powder according to claim 6 , wherein a content of the polymer (A) is 10% to 80% by mass with respect to a total mass of the multi-stage polymer (M).

9. A resin composition., comprising: a solution of the acrylic resin powder according to claim 1 in a polyalkylene glycol.

10. The resin composition according to claim 9 , wherein the polyalkylene glycol has a number average molecular weight of 200 to 5000.

11. The resin composition according to claim 9 , further comprising:
a polyester polyol.

12. A method for producing a resin composition, comprising:
dissolving the acrylic resin powder obtained by the method according to claim 6 , in a polyalkylene glycol.

13. A hot melt adhesive comprising a urethane prepolymer obtained by mixing the resin composition according to claim 9 with an isocyanate.

14. A method for producing a hot melt adhesive, comprising:
dissolving the acrylic resin powder obtained by the method according to claim 6 , in a polyalkylene glycol to obtain a resin composition; and
mixing the resin composition with an isocyanate to obtain a urethane prepolymer.

Assignees

• Mitsubishi Chem Corp

Inventors

• MIYAI Shogo
• Kondo Toru

Classifications

• C08F265/06 Primary

  Polymerisation of acrylate or methacrylate esters on to polymers thereof · CPC title

• C08F20/14

  Methyl esters {, e.g. methyl (meth)acrylate} · CPC title

• C08G18/6225

  Polymers of esters of acrylic or methacrylic acid · CPC title

• C08J3/12

  Powdering or granulating · CPC title

• C09J133/12

  Homopolymers or copolymers of methyl methacrylate · CPC title