Vinyl chloride polymer composition with improved fusion properties

Abstract: A vinyl chloride polymer formulation having a chlorinated olefin polymer as an impact modifier, and an oxidized high density polyethylene homopolymer having an acid number of from 5 to 40 as a fusion promoter can be converted into shaped articles. The invention includes an improved olefin polymer impact modifier composition for use with vinyl chloride polymer formulations, the composition comprising a combination of said chlorinated olefin polymer and said oxidized high density polyethylene homopolymer. The vinyl chloride polymer formulation of the present inventon is useful, for example, as a feedstock for the preparation of shaped articles such as vinyl siding and vinyl window frames.

Description: The present invention relates to a vinyl chloride polymer composition. More specifically, the invention relates to a vinyl chloride polymer composition suitable for use in extrusion. Vinyl chloride polymer compositions are useful for making shaped articles, such as siding for buildings, preferably exterior sidings for residential homes, window frames, and the like. The preparation of such shaped articles from vinyl chloride polymer compositions via extrusion involves the procedure of converting a powdered formulation of vinyl chloride polymer, impact modifier, and other ingredients into a flowable plastic mass. This conversion involves the "fusion" of the powdered formulation. Known impact modifiers include chlorinated polyethylene, ABS resins, ethylene/vinyl acetate/carbon monoxide terpolymers, and acrylic based polymers such as methyl methacrylate/butadiene/styrene terpolymers. Acrylic based modifiers are the most commonly employed impact modifiers in vinyl chloride polymer formulations used in the vinyl siding industry. Chlorinated polyethylene is also a known impact modifier. However, the use of chlorinate polyethylene as an impact modifier in a given known formulation in place of acrylics will result in a longer fusion time. In view of the fact that chlorinated polyethylene is generally substantially less expensive than acrylics, it would be desirable from an economic standpoint to have a vinyl chloride polymer formulation in which the use of chlorinate polyethylene as an impact modifier would result in a shorter fusion time comparable to the fusion time of vinyl chloride polymer formulations having acrylic impact modifiers. The present invention is such a vinyl chloride polymer formulation having a chlorinated olefin polymer as an impact modifier, and a fusion promoting amount of an oxidized high density polyethylene homopolymer having an acid number of from 5 to 40. In another aspect, the invention is a process wherein such a formulation is converted into a shaped article. In yet another aspect, the invention is an improved olefin polymer impact modifier composition for use with vinyl chloride polymer formulations, the composition comprising a combination of the chlorinated olefin polymer and the oxidized high density polyethylene homopolymer. The vinyl chloride polymer formulation of the present invention is useful, for example, as a feedstock for the preparation of shaped articles, such as sidings, window frames, or the like. The process of the present invention requires the presence of a vinyl chloride polymer, chlorinated olefin polymer and an oxidized high density polyethylene homopolymer. The vinyl chloride polymer employed in the present invention contains at least about 95 weight percent of polymerized vinyl chloride in the polymer molecule with the remainder being at least one monoethylenically unsaturated comonomer. The vinyl chloride polymer included in the polymer blends can be any rigid of essentially rigid vinyl chloride polymer such as vinyl chloride homopolymers and interpolymers of vinyl chloride with interpolymerizable monomers such as vinyl esters of organic acids containing from 1 to 18 carbon atoms, e.g., vinyl acetate, vinyl stearate, and the like; vinylidene chloride; symmetrical dichloroethylene; acrylonitrile; methacrylonitrile; alkyl acrylate esters in which the alkyl group contains from 1 to 8 carbon atoms, e.g., methyl acrylate and butyl acrylate; the corrresponding alkyl methacrylate esters; dialkyl esters of dibasic organic acids in which the alkyl groups contain from 1 to 8 carbon atoms, e.g., dibutyl fumarate, diethyl maleate and the like. Preferably, the vinyl chloride polymer is the homopolymer of vinyl chloride. The chlorinated olefin polymer employed in the present invention is a polymer prepared by the chlorination of an olefin polymer. Preferably, the chlorinated olefin polymer is prepared by chlorinating an olefin polymer having an essentially linear structure, said polymer being selected from polyethylene and interpolymers of ethylene and one or more ethylenically unstaurated comonomers, with ethylene making up at least 90 mole percent of the total monomer composition. It is preferred to employ 1-olefins as comonomers. Examples of preferred 1-olefin monomers include 1-butene and 1-octene. Suitable chlorinated olefin polymers have a weight average molecular weight of at least about 50,000. Preferably, the molecular weight of the chlorinated olefin polymer is between 50,000 and 2,000,000. The chlorinated olefin polymer employed in the present invention suitably has from 15 to 45 weight percent chemically combined chlorine. Preferably, the chemically combined chlorine is from 30 to 40 weight percent of the chlorinated olefin polymer. Preferably, the chlorinated olefin polymer has a crystallinity of less than about 10 percent when containing about 34 or more weight percent of chlorine. Preferred examples of chlorinated polymers are those taught in U.S. Patent Nos. 3,454,544; 3,819,554; and 4,767,823. The chlorinated vinyl polymer composition of the present invention contains chlorinated olefin polymer in an amount sufficient to provide impact resistance over a temperature range of from -20°C to 80°C. More in particular, at least 2 parts by weight of chlorinated olefin polymer per 100 parts by weight of vinyl chloride polymer are employed. Preferably, from 2 to 10 parts by weight of chlorinated olefin polymer per 100 parts by weight of vinyl choride polymer are employed, most preferably, from 4 to 6 parts. The fusion promoter employed in the present invention is an oxidized high density polyethylene homopolymer having an acid number of from 5 to 40, preferably, from 10 to 30, and most preferably from 12 to 18. Suitably, the weight average molecular weight of the oxidized polyethylene homopolymer is from 1,000 to 20,000, preferably from 8,000 to 10,000. It is preferred to employ an oxidized polyethylene homopolymer having an average particle size of from 6 to 15 mils (from 150 to 380 µm (microns). Preferably, the Brookfield melt viscosity is from (4,500 to 15,000) x 10⁻³ N.sec/m² (centipoise) at 150°C, and more preferably is from (8,000 to 9,000) x 10⁻³ N.sec/m² (centipoise) at 150°C. Preferably, the melting point is from 100°C to 150°C, with melting points of from 130°C to 140°C being more preferred. The fusion promoter is employed in an amount sufficient to lower the fusion time of the vinyl chloride polymer formulation from 0.5 to 2.0, preferably from 1 to 1.5 minutes when the formulation is employed in a torque rheometer set at 175°C running at 60 RPM. In a typical formulation, the oxidized polyethylene is employed in a amount ranging from 0.05 to 0.4 parts by weight per 100 parts of vinyl chloride polymer, preferably, from 0.05 to 0.2 parts. Generally speaking, within the foregoing limitations, the amount of oxidized polyethylene employed is higher when lead compounds are included in the formulation due to the high degree of external lubricity of such lead compounds. One aspect of the present invention is a composition comprising a chlorinated olefin polymer and an oxidized high density polyethylene homopolymer. Typically, from 1 to 3 weight parts of oxidized polyethylene are employed per 100 weight parts of chlorinated olefin polymer, preferably from 1.5 to 2.5 parts. This composition is readily prepared, for example, by dry blending, for example in a ribbon blender, the oxidized polyethylene with the chlorinated olefin polymer during the preparation of the chlorinated olefin polymer. For example, the oxidized polyethylene can be admixed with the chlorinated olefin polymer just prior to bagging the composition. The compositions of the present ionvention are useful in the preparation of extruded vinyl containing shaped articles, such as vinyl siding for private or commercial buildings. In such applications, it is common to employ other ingredients such as pigments, stabilizers, lubricants, fillers, antistatic agents, dulling or flattening agents, antioxidants and the like, as is well known to those skilled in the art. Extrusion, using the composition of the present invention surprisingly allows for the use of the same extrusion equipment and conditions as are used with formulations which contain acrylic or predominantly acrylic impact modifiers. Thus, the composition of the present invention fuses more quickly than prior art compositions which contain chlorinated olefin polymer impact modifiers. The following preparations and examples are illustrative of the present invention and are not to be construed as limiting. All parts and percentages are by weight unless otherwise specified. Preparation One An extrudable vinyl chloride polymer composition is prepared by intensive dry mixing of the following ingredients: Component Parts by Weight PVC Resin K-65 100 Chlorinated polyethylene impact modifier 6 Heat Stabilizer 1.5 Calcium Stearate 1.0 Paraffin Wax (73.9°C) 1.0 Acrylic Process Aid 1.5 TiO₂ 10.0 CaCO₃ 5.0 The fusion time of this material is recorded in Table I. Example 1-5 The procedure of Preparation One is repeated except that an oxidized high density polyethylene homopolymer, available under the trade name Polyethylene AC-316A from Allied Signal Incorporated, is also employed in the composition. The amount of fusion promoter and the fusion time for each composition is recorded in Table I. Comparative Experiment 6 (Not an embodiment of the present invention) A composition is prepared according to the procedure of Preparation One except that the chlorinated polyethylene impact modifier is replaced with 6 parts of an acrylic modifier available from M & T Chemicals, Inc. under the trade name D-200. The fusion time for this composition is recorded in Table I. As can be seen from the data in Table I, the fusion time surprisingly decreases with the use of the oxidized high density polyethylene fusion promoter. Unexpectedly, Example 1 shows that the addition of a very small amount of 0.05 part of oxidized high density polyethylene homopolymer lowers the fusion time of the composition of Preparation 1. The addition of 0.1 part of the homopolymer lowers the fusion time of the composition to about the same fusion time obtained using an acrylic impact modifier containing composition. Examples 3 to 5 indicate that higher levels of oxidized high density polyethylene homopolymer can be employed to achieve faster fusion. Faster fusion is required, for example, with higher levels of filler, or with higher extrusion rates. Accordingly, the present invention can be employed to provide economic advantages, such as, for example, by using a composition having more filler, thus lowering the cost of the extrudable composition. Similarly, the cost of operation can be reduced by using the composition of the invention to extrude at higher rates. Effect of Fusion Promoter Concentration on Fusion Time Composition Parts OPE Fusion Time (Min.) Prep'n 1 zero >2.5 Ex. 1 0.05 2.0 Ex. 2 0.1 1.4 Ex. 3 0.2 1.0 Ex. 4 0.3 .75 Ex. 5 0.4 .5 C.E. 6 zero 1.5

Claims: A composition comprising polyvinyl chloride, an impact modifying amount of a chlorinated olefin polymer of at least 2 parts by weight of chlorinated olefin polymer per 100 parts by weight of vinyl chloride polymer, which chlorinated olefin polymer has a chlorine content of from 15 to 45 weight percent, and fusion promoting amount of an oxidized high density polyethylene homopolymer of 0.05 to 0.4 parts by weight per 100 parts of vinyl chloride polymer, which oxidized homopolymer has an acid number of from 5 to 40. The composition of claim 1, wherein the oxidized homopolymer has a weight average molecular weight of from 1,000 to 20,000; a Brookfield melt viscosity of from (4,500 to 15,000) x 10⁻³ N.sec/m² (cps) at a temperature of 150°C; an average particle size of from 150 to 380 µm (microns); and a melting point of from 100°C to 150°C. The composition of claim 1 or 2, wherein the amount of oxidized homopolymer is from 0.05 to 0.15 weight parts of polyvinyl chloride. The composition of claim 1, 2 or 3, wherein the oxidized homopolymer has an acid number of from 10 to 30, and comprises from 1.5 to 2.5 parts oxidized polyethylene per 100 parts of the chlorinated olefin polymer. A fabricated article prepared from the composition of claim 1. A composition comprising a chlorinated olefin polymer having a chlorine content of from 15 to 45 percent and from 1 to 3 parts per 100 parts of the chlorinated olefin polymer of an oxidized high density polyethylene homopolymer having an acid number of from 5 to 40. The composition of claim 6, comprising from 1.5 to 2.5 parts of oxidized homopolymer having an acid number of from 10 to 30. The composition of claim 6 or 7, wherein the chlorinated olefin polymer is chlorinated polyethylene having a chlorine content of from 30 to 40 percent. The composition of claim 6, 7 or 8, wherein the oxidized homopolymer has a weight average molecular weight of from 1,000 to 20,000; a Brookfield melt viscosity of from (4,500 to 15,000) x 10⁻³ N.sec/m² (cps) at a temperature of 150°C; an average particle size of from 150 to 380 µm (microns); and a melting point of from 100°C to 150°C. A process for improving the fusion of a composition comprising polyvinyl chloride and an impact-modifying amount of a chlorinated olefin polymer of at least 2 parts by weight of chlorinated olefin polymer per 100 parts by weight of vinyl chloride polymer, which chlorinated olefin polymer has a chlorine content of from 15 to 45 percent, characterized by admixing with the polyvinyl chloride and the chlorinated olefin polymer from 0.05 to 0.4 weight parts per 100 weight parts of polyvinyl chloride of an oxidized high density polyethylene homopolymer having an acid number of from 5 to 40 to give the composition a fusion time of from 0.5 to 2.0 minutes when measured on a Haake torque rheometer charged with 65 grams of material and operating at 60 RPM and 175°C. The process of claim 10, wherein the fusion time is from 1 to 1.5 minutes.

Inventors: PREJEAN THOMAS GLENN, PREJEAN, THOMAS GLENN
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1990
Main classification: C08L27
IPC codes: C08L27, C08L23