Acrylic polymer capstock with improved adhesion to structural plastics

1. A composite product comprised of a layer of polystyrene structural plastic having a 0.1 to about 2.5 mm thin protective layer comprising:

a) 10-95% polymethyl methacrylate or an C 1 -C 6 alkyl methacrylate C 1 -C 8 alkyl acrylate copolymer matrix

b) 0-60% modifiers; and

c) 5-40% acrylic polymer additive that increases the adhesive strength between the layers which is comprised of

20-80% methyl methacrylate,

20-80% butyl methacrylate, and

0-15% methacrylic acid, acrylic acid or C 1 -C 5 esters thereof.

2. The composite product of claim 1 wherein the acrylic polymer additive is comprised of 20-80% methyl methacrylate and 20-80% butyl methacrylate has a molecular weight from 40,000-300,000.

3. The composite product of claim 2 wherein the acrylic polymer additive is comprised of 50-80% methyl methacrylate and 20-50% butyl methacrylate and has a molecular weight from 40,000-100,000.

4. A co-extruded product comprised of two layers

(a) a first layer comprised of polystyrene structural plastic and

(b) a second layer comprised of

(i) methyl methacrylate resin, and

(ii) an acrylic polymer additive that increases the adhesive strength between the layers which is comprised of

(i) 20-80% methyl methacrylate,

(ii) 20-80% butyl methacrylate, and

(iii) 0-15% methacrylic acid, acrylic acid or C 1 -C 5 esters thereof.

5. The product of claim 4 wherein the polystyrene structural plastic is a copolymer of acrylonitrilc/butadiene/styrene.

6. The product of claim 4 wherein the polystyrene is high impact polystyrene or crystalline polystyrene.

7. The product of claim 4 wherein ratio of the monomer units is

(a) 50 to 80 wt % methyl methacrylate,

(b) 20 to 50 wt % butyl methacrylate and

(c) 0 to 10 wt % methacrylic acid.

8. The product of claim 4 wherein the second layer is comprised of

(i) 60 to 95 wt % of methylmethacrylate resin and

(ii) 5 to 40 wt % of the acrylic polymer additive.

9. The product of claim 4 wherein the first layer contains pigments, dyes, fillers, PS, acrylic and HIPS rework, different grades of HIPS.

10. A co-extruded product comprised of two layers

(A) 50 to 95 wt % being a first layer comprised of high impact polystyrene, and

(B) 5 to 50 wt % being a second layer being comprised of

(i) 60 to 95 wt % of an acrylate resin, and

(ii) 5 to 40 wt % of an acrylic polymer additive which is copolymer or terpolymer that increases the adhesive strength between the layers which is comprised of

(i) 20-80% methyl methacrylate,

(ii) 20-80% butyl methacrylate, and

(iii) 0-15% methacrylic acid, acrylic acid or C 1 -C 5 esters thereof.

11. The product of claim 10 wherein the acrylic polymer additive is a 50-80% methyl methacrylate and 20-50% butyl methacrylate polymer having a molecular weight from 40,000-300,000.

12. The product of claim 10 wherein the acrylic polymer additive is a 20-50% methyl methacrylate and 50-80% butyl methacrylate having a molecular weight from 40,000-100,000.

13. A process for producing a composite of a polystyrene structural plastic and a 0.1 to about 2.5 mm thin protective layer, the process comprises joining a molten stream of polystyrene structural plastic and a molten stream of a blend of an acrylic ester polymer and an acrylic polymeric additive in an extruder discharge conduit to form a single stratified stream of molten material conforming to the cross-section of the conduit and having a relatively sharply defined interface between the structural plastic and the blend, and thereafter passing the stratified stream through a sheet-form extrusion die having its die lips generally aligned with the foregoing interface.