Feedblock coextrusion of modified acrylic capstock

• US 5,318,737 A
• Filed: 11/12/1992
• Issued: 06/07/1994
• Est. Priority Date: 05/25/1990
• Status: Expired due to Term

• Current Assignee: Rohm and Haas Company (Dow, Inc.)
• Original Assignee: Rohm and Haas Company (Dow, Inc.)
• Inventors: Post, Robert L., Trabert, Loren D., Ludwig, Edward G.
• Primary Examiner(s): Thurlow, Jeffery
• Application Number:
  US07/975,152
• Time in Patent Office: 572 Days
• Field of Search: 264/171, 264/177.1, 264/177.17, 264/177.19, 264/331.18, 425/131.1, 425/133.5, 425/462
• US Class Current: 264/173.16
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/30 comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: C08L 2205/22 Mixtures comprising a continuous polymer matrix in which are dispersed crosslinked particles of another polymer
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 33/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C08L 51/00 Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds for ABS polymers C08L55/02; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 51/06 grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond

Abstract

A method for preparing a plastic composite by feedblock coextrusion of a molten acrylic based capstock overlying and integrally bonded to an underlying structural plastic ply. The composition of the capstock contains from about 40 to about 88 wt. % of an acrylic polymer having a molecular weight of at least about 125,000 daltons, and from about 12 to about 60 wt. % of an acrylate-based impact modifier resin in the form of discrete multi-layered polymeric particles. The capstock composition has a melt flow index of about 0.4 to about 0.75 grams/10 minutes (ASTM Method D-1238, Condition I) and the underlying structural ply has substantially the same melt flow index as that of the capstock composition.

Claims

1. A method for preparing a plastic composite comprising capstock overlying and integrally bonded to an underlying structural ply, wherein said composite is formed by feedblock coextrusion of a molten capstock composition and a molten structural ply composition, the improvement comprising:

forming by feedblock coextrusion the composite from the capstock composition comprising

(A) about 40 to about 88 wt. % of a thermoplastic resin having a molecular weight of at least about 125,000 daltons, and selected from the group consisting of methyl methacrylate resin and a copolymer of methyl methacrylate and a C₁ to C₄ alkyl acrylate, and

(B) about 12 to about 60 wt. % of an acrylate-based impact-modifier resin in the form of discrete multi-layer polymeric particles, wherein the composition has a melt flow index of from about 0.4 to about 0.75, as measured by ASTM Method D-1238, Condition I, and wherein the discrete multi-layered polymeric particles are dispersed in the thermoplastic resin which constitutes a continuous phase of the composition;

and from a structural ply composition having substantially the same melt flow index as that of the capstock composition.

2. The method of claim 1 wherein the thermoplastic resin consists essentially of a copolymer of about 0.1 to about 12 wt. % of alkyl acrylate and about 88 to about 99.9 wt. % of methyl methacrylate.

3. The method of claim 2 including about 0.1 to about 4 wt. % of alkyl acrylate and about 96 to about 99.9 wt. % of methyl methacrylate.

4. The method of claim 2 wherein the molecular weight is no greater than about 220,000 daltons and the melt flow index is about 0.45 to about 0.6.

5. The method of claim 2 wherein the impact-modifier resin comprises multi-layered polymeric particles having an intermediate layer sandwiched between a core layer and an outer layer, the core layer being a non-elastomeric polymer, the intermediate layer being an elastomeric polymer, and the outer layer being a hard polymer.

6. The method of claim 5 wherein each of the core and outer layers comprises random copolymers of methyl methacrylate and ethyl acrylate and the intermediate layer comprises a random copolymer of butyl acrylate and styrene.

7. The method of claim 2 wherein a source of the impact-modifier resin is an admixture which includes a drying aid resin comprising a random copolymer of about 90 to about 99.9 methyl methacrylate and about 0.1 to about 10 wt. % of an alkyl acrylate having a molecular weight of about 95,000 to about 200,000 daltons.

8. The method of claim 1 wherein the structural ply composition is selected from ABS, polycarbonate, polycarbonate-ABS blends, or PVC.

9. The method of claim 1 wherein the capstock composition overlies a mutually compatible polymer interlayer integrally bonded to the underlying structural ply.

10. The method of claim 9 wherein the mutually compatible polymer interlayer is ABS and the underlying structural ply is high impact polystyrene.

11. The method of claim 9 wherein the mutually compatible polymer interlayer is a propylene polymer grated with methyl methacrylate and the underlying structural ply is polypropylene.