Thermoplastic and thermoset polymer compositions

• US 5,346,954 A
• Filed: 11/17/1992
• Issued: 09/13/1994
• Est. Priority Date: 11/18/1986
• Status: Expired due to Term

• Current Assignee: Arkema France (Arkema)
• Original Assignee: Rohm and Haas Company (Dow, Inc.)
• Inventors: Wu, Jiun-Chen, Work, William J., Bortnick, Newman M., Dunkelberger, David L.
• Primary Examiner(s): Seccuro, Jr., Carman J.
• Application Number:
  US07/977,592
• Time in Patent Office: 665 Days
• Field of Search: 525/85, 525/81, 525/71, 525/64, 525/66, 525/67, 525/54.2, 525/227, 525/228, 525/931, 525/932, 526/909
• US Class Current: 525/85
• CPC Class Codes: C08F 265/04 on to polymers of esters
• CPC Class Codes: Y10S 525/931 Blend of stated incompatibility
• CPC Class Codes: Y10S 525/932 Blend of matched optical properties

Abstract

Polymer particles in a size range between 2 and 15 micrometers, and having a refractive index close to, but not identical with, that of a matrix polymer and optionally having one or more enclosing shells, the outer shell being compatible with the matrix polymer, impart light-diffusing properties to the matrix polymer without degrading its physical properties, while the particles having a closer refractive index match to the matrix polymer impart gloss reduction to the surface of the matrix polymer.

Claims

1. A process for preparing a thermoplastic polymer composition comprising thermoplastic matrix polymer and, distributed throughout the thermoplastic matrix polymer, substantially spherical core-shell polymer particles, said particles having an average diameter of from 2 to 15 μ

m and a particle size distribution such that at least 90% by weight of the particles fall within ±

20% of the average particle diameter, a core of rubbery alkyl acrylate polymer and one or more shells, the outer shell of which is compatible with the matrix polymer, wherein the process comprises;

A) polymerizing a first aqueous emulsion of the one or more monomers which, when polymerized, produce a particulate composition comprising polymer particles;

B) performing one or more times the steps of

1) swelling the particles of the particulate composition produced in A), or if appropriate the particles of B2), with one or more monomers, and

2) polymerizing the swelling monomer within the particles until all of the monomers have been polymerized; and

c) polymerizing one or more monomers which are polymerizable to form a polymer compatible with the matrix polymer to produce the core-shell polymer particles,

and blending the resulting core-shell polymer particles, in an amount of 0.1 to 40% by weight of the total composition, with said thermoplastic matrix polymer.

2. The process of claim 1 wherein the polymerization of step A) is conducted under conditions that form the emulsion polymer as an easily swellable oligomer.

3. The process of claim 1 wherein one or more polymerizations of step B2) are conducted under conditions that form a readily swellable oligomer from the swelling monomer.

4. The process of claim 1 wherein said spherical core-shell polymer particles comprise a rubbery alkyl acrylate polymer, the alkyl group having from 2 to 8 carbon atoms, copolymerized with 0 to about 10% crosslinker and 0 to about 10% graftlinker, based on the total weight of the particles.

5. The process of claim 1 wherein said matrix polymer is substantially amorphous.

6. The process of claim 5 wherein the spherical polymeric particles of step B2), have a refractive index (n_D²⁵) within ±

0.2 units of the refractive index of the matrix polymer.

7. The process of claim 6 wherein the refractive index of the spherical particles of step B2) is no closer than ±

0.003 units of the refractive index of the matrix polymer.

8. The process of claim 1 wherein the process further comprises performing one or more steps of

C1) suspending the core polymer particles in a second aqueous monomer emulsion, the monomers of which are polymerizable to form a polymer compatible with the matrix polymer, and

C2) polymerizing onto the core polymer particles a polymer shell from the monomer in the second emulsion.

9. The process of claim 8 wherein the spherical polymer particles of step B2 have a refractive index within ±

0.2 units of the refractive index of the matrix polymer.