Composition and method for extruding plastic articles having accent color pattern and comprising poly-.alpha.-methylstyrene pellets

• US 5,869,176 A
• Filed: 11/06/1997
• Issued: 02/09/1999
• Est. Priority Date: 04/03/1996
• Status: Expired due to Fees

• Current Assignee: Polyone Corporation (Avient Corp.)
• Original Assignee: M A Hannacolor
• Inventors: Harris, Ronald M., Dorchester, John J., Smith, Bobby D.
• Primary Examiner(s): Le, Hoa T.
• Application Number:
  US08/965,236
• Time in Patent Office: 460 Days
• Field of Search: 428/15, 428/215, 428/323, 428/327, 428/328, 428/212
• US Class Current: 428/327
• CPC Class Codes: B29C 48/0022 combined with cutting
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/16 Articles comprising two or more components, e.g. co-extruded layers
• CPC Class Codes: B29C 48/17 the components having different colours
• CPC Class Codes: B29C 48/175 comprising a multi-coloured single component, e.g. striated, marbled or wood-like patterned
• CPC Class Codes: B29C 59/04 using rollers or endless belts
• CPC Class Codes: B29K 2027/06 PVC, i.e. polyvinylchloride
• CPC Class Codes: B29L 2007/002 Panels; Plates; Sheets
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/254 Polymeric or resinous material
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof

Abstract

A new and useful a plastic article, particularly plastic siding, with an accent color pattern incorporated therein, a specially formed accent color pellet which is useful in manufacturing such an article, and a process for producing the article using the pellets are provided. The process contemplates extruding a plastic product from a base material formed of powder-sized particles and specially formed accent color pellets. The accent color pellets are alloyed masses of resins and pigment which are larger than the powder particles of the base material, and have a higher vicat softening point temperature than the base material. The alloyed pellets are designed to melt controllably and to mix controllably with the base material. During the extrusion process, the accent color pellets begin to soften and disperse later than the base material, and cause controllable dispersion of the accent color into the base material, thereby producing accent color streaks in the resulting product having controllable characteristics. The process is particularly suited for producing a simulated wood-grain or streaking effect in plastic siding, and as described can produce hard streaking, soft streaking, and a mottled or variegated streaking in which more than one accent color is used simultaneously. A novel formulation for the accent color pellets is disclosed, in which poly-α-methylstyrene is used as the only high vicat softening temperature resin.

Claims

1. An extruded plastic article having a controllable and realistic wood-grain appearance, the article comprising a capstock base material and accent color pellets, said capstock base material having a vicat softening temperature, said accent color pellets (i) having a higher vicat softening temperature than said base material, and (ii) comprising poly-α

-methylstyrene having a high vicat softening temperature and a melt flow index of greater than or equal to 1.0 gram per 10 minutes, and at least one additional resin having a substantially lower vicat softening temperature than said first resin.

2. The extruded plastic article of claim 1, wherein said accent color pellets have a vicat softening temperature that is about 15°

C. to about 50°

C. higher than the vicat softening temperature of the capstock base material.

3. The extruded plastic article of claim 2, wherein said accent color pellets have a vicat softening temperature that is about 20°

C. to about 40°

C. higher than the vicat softening temperature of the capstock base material.

4. The extruded plastic article of claim 1, wherein said accent color pellets have a vicat softening temperature of about 100°

C. to about 160°

C.

5. The extruded plastic article of claim 4, wherein said accent color pellets have a vicat softening temperature of about 110°

C. to about 150°

C.

6. The extruded plastic article of claim 5, wherein said accent color pellets have a vicat softening temperature of about 120°

C. to about 140°

C.

7. The extruded plastic article of claim 1, wherein the additional resin is an acrylic.

8. The extruded plastic article of claim 1, wherein the capstock base material comprises polyvinyl chloride.

9. The extruded plastic article of claim 1, wherein the plastic article is a siding material that further comprises a substrate coextruded with the capstock base material.

10. The extruded plastic article of claim 9, wherein said accent color pellets make up from about 1% to about 10% of the total weight of said siding material.

11. An extruded plastic article having a controllable and realistic wood-grain appearance, the article comprising a capstock base material and accent color pellets, said capstock base material having a vicat softening temperature, said accent color pellets having a vicat softening temperature that is about 15°

C. to about 50°

C. higher than the vicat softening temperature of said base material, said accent color pellets comprising (i) about 10% to about 30% by weight poly-α

-methylstyrene, (ii) about 30% to about 50% by weight of at least one additional resin having a substantially lower vicat softening temperature than the poly-α

-methylstyrene, and (iii) about 30% to about 45% by weight of a color pigment.

12. The extruded plastic article of claim 11, wherein the poly-α

-methylstyrene has a vicat softening temperature greater than about 170°

C.

13. The extruded plastic article of claim 11, wherein the pellets comprise about 12% to about 27% by weight poly-α

-methylstyrene and about 35% to about 45% by weight of the additional resin.

14. The extruded plastic article of claim 11, wherein the pellet comprises about 16% to about 25% by weight poly-α

-methylstyrene and about 28% to about 44% of the additional resin.

15. The extruded plastic article of claim 11, wherein the capstock base material contains no added color pigment material, and the accent color pellets provide a background color and at least one accent color to the capstock.

16. The extruded plastic article of claim 11, wherein the additional resin is an acrylic.

17. The extruded plastic article of claim 11, wherein the poly-α

-methylstyrene has a vicat softening temperature greater than about 151°

C.

18. The extruded plastic article of claim 11, wherein the capstock base material comprises polyvinyl chloride.

19. The extruded plastic article of claim 11, wherein the plastic article is a siding material that further comprises a substrate coextruded with the capstock base material.