Process for making polyvinyl chloride compositions having high heat distortion temperatures

• US 5,502,111 A
• Filed: 04/12/1994
• Issued: 03/26/1996
• Est. Priority Date: 03/06/1991
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Huynh-Ba, Gia
• Primary Examiner(s): Thibodeau, Paul J.
• Assistant Examiner(s): Critharis, Mary
• Application Number:
  US08/226,427
• Time in Patent Office: 714 Days
• Field of Search: 525/203, 525/205, 525/207, 525/227, 525/208, 525/239, 525/238, 525/240, 525/241
• US Class Current: 525/239
• CPC Class Codes: C08L 23/08 Copolymers of ethene C08L23/16 takes precedence
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• 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 27/06 Homopolymers or copolymers of vinyl chloride
• CPC Class Codes: C08L 33/24 Homopolymers or copolymers of amides or imides

Abstract

Heat distortion temperature of polyvinyl chloride compositions can be significantly increased above the heat distortion temperature of uncompounded polyvinyl chloride while good appearance of extruded material is preserved by preblending an imidized acrylic resin having a glass transition temperature above 130° C. with a third polymer melt-processable throughout the temperature range of 150°-300° C. under conditions where a two-phase blend is formed, wherein the third polymer forms the continuous phase and the imidized acrylic resin forms the dispersed phase and then melt-blending the two-phase blend with polyvinyl chloride at a temperature of 150°-220° C. to form a composition in which the imidized acrylic resin forms a substantially homogeneous blend with polyvinyl chloride. It also is possible to preblend imidized acrylic resin with a third polymer with which it is compatible, for example, another imidized acrylic resin having a sufficiently low glass transition temperature to lower the resulting glass transition temperature of the preblend below about 130° C., which then is blended with polyvinyl chloride.

Claims

1. A process for the manufacture of a polyvinyl chloride composition having an improved heat distortion temperature, said process comprising blending at a temperature set within a range of about 150°

-220°

C.

(A) 50-95 parts by weight of polyvinyl chloride with

(B) a complementary amount, the total adding to 100 parts by weight, of a polymer blend, comprising a matrix and a dispersed phase, consisting essentially of about

(i) 30-85 weight percent of a dispersed phase of an imidized acrylic resin having a glass transition temperature above 150°

C., as determined according to ASTM standard D3418, taking the midpoint value, and a flexural modulus of at least 690 kPa wherein at least 20% of ester groups originally present in the resin are imidized to units of the following formula (1);

##STR2## wherein each one of R1, R2, and R3 independently is hydrogen or a C₁ -C₂₀ alkyl, cycloalkyl, or aryl group, said imidized acrylic resin further containing 0-50 weight percent of a copolymerized ethylenically tinsaturated additional monomer and being substantially free of functional groups capable causing degradation of polyvinyl chloride within the temperature range of about 150°

-220°

C.;

said resin being melt-processable at a temperature within the range of about 200°

to 300°

C.;

(ii) 15-70 weight percent of a matrix of a third polymer, which is melt processable throughout the temperature range of about 150°

to 300°

C. and is substantially free of functional groups capable of causing degradation of imidized acrylic resin within the temperature range of about 200°

-300°

C. and of polyvinyl chloride within the temperature range of about 150°

-220°

C.;

said polymer blend (B) of imidized acrylic resin (i) with third polymer (ii) being melt-processable below about 220°

C.;

blending of polyvinyl chloride with polymer blend (B) being conducted under such temperature and shear conditions that blend (B) becomes dispersed in polyvinyl chloride; and

substantially all of the imidized acrylic resin (i) forms compatible, single-phase composition with polyvinyl chloride.

2. A process of claim 1 wherein each one of R1, R2, and R3 is methyl.

3. A process of claim 1 wherein and the degree of imidization of the resin is about 60-100%.

4. A process of claim 3 wherein the glass transition temperature of imidized acrylic resin (i) is about 155°

-165°

C., as determined according to ASTM standard D3418, taking the midpoint value.

5. A process of claim 1 wherein the temperature at which polyvinyl chloride is blended with blend (B) is about 160°

-210°

C.