Polymer powder composition and its method of preparation

Patent metadata

Field	Value
Publication number	US-2017174847-A1
Application number	US-201515301811-A
Country	US
Kind code	A1
Filing date	Apr 7, 2015
Priority date	Apr 7, 2014
Publication date	Jun 22, 2017
Grant date	—

Abstract

The present invention relates to a non dusty polymer powder composed of aggregated latex particles prepared by a multistage preparation process.

First claim

1 . A polymer composition in form of polymeric particles comprising
at least one stage forming a layer (B) comprising a polymer (B1) having a glass transition temperature of at least 60° C. and at least one stage forming a layer (A) comprising a polymer (A1) having a glass transition temperature of less than 60° C.,
obtained by a multistage process wherein the weight ratio r of the layer (A) in the composition comprising the two layers is at least 1 wt %, and wherein the layer (A) comprising a polymer (A1) having a glass transition temperature of less then 60° C. is a stage forming the outer layer of the polymeric particles.

2 . The polymer composition according to claim 1 wherein the layer (B) comprising a polymer (B1) having a glass transition temperature of at least 60° C. is a stage forming an inner layer of the polymeric particles.

3 . The polymer composition according to claim 1 wherein the weight ratio r in wt % of the layer (A) comprising polymer (A1) in a complete polymer particle is at least as defined by following formula

r
=

be
aT

+
1
+

1

363
-
T

wherein the variable T is the glass transition temperature Tg expressed in Kelvin of the polymer (A1) of the layer (A) and the exponent a is at least 0.024 and factor b is at least 0.0053 and the exponent a is at most 0.028 and the factor h is at most 0.007.

4 . The polymer composition according to claim 1 wherein that the weight ratio r in wt % of the layer (A) comprising polymer (A1) in a complete polymer particle for a Tg between 200K and 333K of the polymer (A1) is at least a defined by following formula
r=b 1 e a 1 T

wherein the variable T is the glass transition temperature Tg expressed in Kelvin of the polymer (A1) of the external layer (A) and the exponent a1 is at least 0.0255 and the factor b1 is at least 0.0055 and the exponent a1 is at most 0.028 and the factor b1 is at most 0.007.

5 . The polymer composition according to claim 1 wherein the weight ratio r in wt % of the layer (A) comprising polymer (A1) in a complete polymer particle is at most 30 wt %.

6 . The polymer composition according to claim 1 wherein the polymer (A1) is a (meth) acrylic polymer.

7 . The polymer composition according to claim 1 wherein the polymer (A1) comprises at least 70 wt % monomers chosen from the group consisting of C1 to C12 alkyl (meth)acrylates.

8 . The polymer composition according to claim 1 wherein the polymer (A1) comprises acrylic or methacrylic monomers that are chosen from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, tert-butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and mixtures thereof.

9 . The polymer composition according to claim 1 wherein the glass transition temperature Tg of the polymer (A1) is between −50° C. and 50° C.

10 . The polymer composition according to claim 1 wherein the polymer (B1) is a (meth) acrylic polymer.

11 . The polymer composition according to claim 1 wherein the polymer (B1) comprises at least 70% monomers chosen from the group consisting of C1 to C12 alkyl (meth)acrylates.

12 . The polymer composition according to claim 1 wherein the polymer (B1) comprises acrylic or methacrylic monomers that are chosen from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and mixtures thereof.

13 . The polymer composition according to claim 1 wherein the glass transition temperature Tg of the polymer (B1) is between 60° C. and 150° C.

14 . The polymer composition according to claim 1 wherein a mass average molecular weight Mw of the polymer (A1) is less than 1 000 000 g/mol.

15 . The polymer composition according to claim 1 wherein a mass average molecular weight of the polymer (B1) is at least 300 000 g/mol.

16 . A method for manufacturing the polymer composition comprising the steps of:
a) polymerizing by emulsion polymerization of a monomer or monomer mixture (B m ) to obtain layer (B) comprising a polymer (B1) having a glass transition temperature of at least 60° C. b) polymerizing by emulsion polymerization of a monomer or monomer mixture (A m ) to obtain one layer (A) comprising polymer (A1) having a glass transition temperature of less than 60° C.
wherein the weight ratio r of the obtained layer (A) in the composition comprising the two layers is at least 1 wt %, and wherein step a) is made before step b).

17 . The method according to claim 16 , wherein step a) is made before step h).

18 . The method according to claim 16 wherein step b) is performed in presence of the polymer (B) obtained in step a).

19 . The method according to claim 16 wherein the method comprises an additional drying step c) by spray drying.

20 . The method according to claim 16 wherein the weight ratio r in wt % of the layer (A) comprising polymer (A1) in the complete polymer particle is at least as defined by following formula

r
=

be
aT

+
1
+

1

363
-
T

wherein the variable T is the glass transition temperature Tg expressed in Kelvin of the polymer (A1) of the layer (A) and the exponent a is at least 0.024 and factor b is at least 0.0053.

21 . The method according to claim 16 wherein the weight ratio r in wt % of the layer (A) comprising polymer (A1) in a complete polymer particle at most 30 wt %.

22 . (canceled)

Assignees

• Arkema France

Inventors

• Pirri Rosangela
• Hajji Philippe
• Schipper Christiaan A

Classifications

• C08J7/0427

  with only one layer of a composition containing a polymer binder (with more layers C08J7/042) · CPC title

• C08J3/126 Primary

  Polymer particles coated by polymer, e.g. core shell structures · CPC title

• C08F212/08

  Styrene · CPC title

• C08F265/06

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

• C08J3/12

  Powdering or granulating · CPC title