Acrylic polymer fine particles and plastisol using the same

• US 20010016612A1
• Filed: 01/02/2001
• Published: 08/23/2001
• Est. Priority Date: 07/01/1998
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Rayon Company Limited (Mitsubishi Chemical Holdings Corporation)
• Inventors: Kasai, Toshihiro
• Granted Patent: US 6,433,048 B2
• Time in Patent Office: Days
• US Class Current: 523/201
• CPC Class Codes: C08F 2/22 Emulsion polymerisation
• CPC Class Codes: C08F 265/06 Polymerisation of acrylate or methacrylate esters on to polymers thereof
• CPC Class Codes: Y10S 525/902 Core-shell

Abstract

Acrylic polymer fine particles which comprise primary particles P of 250 nm or more in average particle diameter having a core shell structure and plastisols prepared using the same.

In the fine particles, a core polymer C and a shell polymer S are copolymers of the following monomer mixtures Mc and Ms, respectively, and the weight ratio of Mc and Ms is 10/90-90/10:

Mc:

methyl methacrylate 20-85 mol %

(meth)acrylic ester of C₂-C₈ aliphatic alcohol and/or aromatic alcohol 15-80 mol %

other copolymerizable monomers not more than 30 mol %;

, when the total amount of these monomers is 100 mol %;

Ms:

methyl methacrylate 20-79.5 mol %

(meth)acrylic ester of C₂-C₈ aliphatic alcohol and/or aromatic alcohol 5-40 mol %

a monomer containing carboxyl group or sulfonic acid group 0.5-10 mol %

other copolymerizable monomers not more than 30 mol %.

Claims

1. Acrylic polymer fine particles which comprise primary particles P having a core-shell structure comprising a core polymer C and a shell polymer S, wherein the average particle diameter of the primary particles P is not less than 250 nm, the core polymer C and the shell polymer S are copolymers of the following monomer mixtures Mc and Ms, respectively, and the weight ratio of Mc and Ms is 10/90-90/10;

Mc;

methyl methacrylate 20-85 mol %

(meth)acrylic ester of C₂-C₈ aliphatic alcohol and/or aromatic alcohol 15-80 mol %, and

other copolymerizable monomers not more than 30 mol %

, when the total amount of these monomers is 100 mol %;

Ms;

methyl methacrylate 20-79.5 mol %

(meth)acrylic ester of C₂-C₈ aliphatic alcohol

and/or aromatic alcohol 5-40 mol %

monomer containing carboxyl group or sulfonic acid group 0.5-10 mol %, and

other copolymerizable monomers not more than 30 mol %

, when the total amount of these monomers is 100 mol %.

2. Acrylic polymer fine particles according to

claim 1

, wherein the core polymer C and the shell polymer S are copolymers of the following monomer mixtures Mc and Ms, respectively, and the weight ratio of Mc and Ms is 30/70-70/30;

Mc;

methyl methacrylate 20-70 mol %

at least one (meth)acrylic ester selected from the group consisting of n-butyl (meth)acrylate, i-butyl (meth)acrylate and t-butyl (meth)acrylate 30-80 mol %, and

other copolymerizable monomers not more than 20 mol %

, when the total amount of these monomers is 100 mol %;

Ms;

methyl methacrylate 30-79.5 mol %

at least one (meth)acrylic ester selected from the group consisting of n-butyl (meth)acrylate, i-butyl (meth)acrylate and t-butyl (meth)acrylate 5-40 mol %

acrylic monomer containing carboxyl group 0.5-10 mol %, and

other copolymerizable monomers not more than 20 mol %

, when the total amount of these monomers is 100 mol %.

3. Acrylic polymer fine particles according to

claim 1

, wherein the core polymer C and the shell polymer S are copolymers of the following monomer mixtures Mc and Ms, respectively, and the weight ratio of Mc and Ms is 30/70-70/30;

Mc;

methyl methacrylate 20-70 mol %

at least one (meth)acrylic ester selected from the group consisting of n-butyl (meth)acrylate, i-butyl (meth)acrylate and t-butyl (meth)acrylate 30-80 mol %, and

other copolymerizable monomers not more than 10 mol %

, when the total amount of these monomers is 100 mol %;

Ms;

methyl methacrylate 55-79.5 mol %,

at least one (meth)acrylic ester selected from the group consisting of n-butyl (meth)acrylate, i-butyl (meth)acrylate and t-butyl (meth)acrylate 20-40 mol %

acrylic monomer containing carboxyl group 0.5-5 mol %, and

other copolymerizable monomers not more than 10 mol %

, when the total amount of these monomers is 100 mol %.

4. A plastisol containing the acrylic polymer fine particles according to any one of claims 1-3 and a plasticizer.

5. A plastisol according to

claim 4

, wherein the main component of the plasticizer is a dialkyl phthalate compound.

6. A method for producing the acrylic polymer fine particles according to any one of claims 1-3, comprising the steps of:

(1) (a) polymerizing, in a medium mainly composed of water, a monomer which has a solubility of not less than 0.02 mass % in said medium at 20°

C. and the polymer of which is insoluble in said medium, using a water-soluble radical polymerization initiator in the absence of emulsifier micelle in said medium, thereby obtaining a polymer dispersion,

(b) adding dropwise a monomer mixture into the said polymer dispersion to obtain a coated polymer dispersion, and

(2) spray drying the polymer dispersion to recover polymer fine particles.