BLEND OF IMPACT MODIFIER, VINYL CHLORIDE POLYMER, AND ACRYLIC RESIN

Abstract: Polymer blends having good hardness and flame retar­ dancy comprise: (1) an interpolymer comprising: (a) cross­ linked (meth)acrylate; (b) crosslinked styreneacrylonitrile polymeric components; and (c) uncrosslinked styrene acry­ lonitrile components (2) an acrylic resin; and (3) a vinyl chloride polymer. The amount of interpolymer (1) in the blend predominates over the respective weight amounts of either of the two other components (2) and (3).

Description: BLEND OF IMPACT MODIFIER, VINYL CHLORIDE POLYMER, AND ACRYLIC RESIN Background of the Invention Field of the Invention The present invention relates to a three component polymer blend having good hardness and flame retardancy for use in making molded parts. Description of the Prior Art Impact resistant, weatherable polymer compositions comprising acrylate, styrene, and acrylonitrile components are known. U.S. Patent No. 3,944,631 to A. J. Yu et al., which discloses one of the components used in the blends of the present invention, describes an interpolymer comprising: (a) crosslinked (meth) acrylate; (b) crosslinked styrene-acrylonitrile; and (c) uncrosslinked styrene-acrylonitrile polymeric components. This material is said to have superior weather resistance as compared to ABS polymers and is only taught in U.S. Patent No. 3,944,631 for use by itself without blending with other polymeric materials. Blends of the polymer composition described in U.S. Patent No. 3,944,631 with certain specific thermoplastic polymers are also described in the literature. For example, U.S. Patent No. 4,168,285 to M. J. Turczyk describes blends of vinyl chloride polymer and the polymer composition shown in U.S. Patent No. 3,944,631. Also, blends of acrylic polymers with this composition are described in pending U.S. Serial No. 176,887, filed August 11, 1980. Three component blends which comprise the composition of U.S. Patent No. 3,944,631 are described in U.S. Patent No. 4,160,793 to P. Kraft et al. in which the other two components are vinyl chloride polymer and chlorinated vinyl chloride polymer. Summary of the Present Invention The polymer blends of the present invention comprise a predominant amount of the interpolymer shown in U.S. Patent No. 3,944,631 with lesser amounts of an acrylic polymer and a vinyl chloride polymer. Such blends have good surface hardness and flame retardancy. They have utility in making molded parts (for example, stadium seats, patio furniture, bus seats and exterior wall pieces, etc.). Description of Preferred Embodiments The terminology "interpolymer comprising crosslinked (meth)acrylate, crosslinked styrene-acrylonitrile and uncrosslinked styrene-acrylonitrile components", as used herein, is meant to encompass the type of interpolymer compositions described and claimed in U.S. Patent No. 3,944,631 to A. J. Yu et al. These interpolymer compositions are formed by a three step, sequential polymerization process, as follows: 1. emulsion polymerizing a monomer charge (herein designated 11(meth)acrylate", for purposes of the present invention), of at least one C2-C10 alkyl acrylate, C8-C22 alkyl methacrylate, or compatible mixtures thereof, in an aqueous polymerization medium in the presence of an effective amount of a suitable di- or polyethylenically unsaturated crosslinking agent for such a monomer, with the C4-C8 alkyl acrylates being the preferred (meth)acrylate monomers for use in this step; ; 2. emulsion polymerizing a monomer charge of styrene and acrylonitrile in an aqueous polymerization medium, also in the presence of an effective amount of a suitable di- or polyethylenically unsaturated crosslinking agent for such a monomer, said polymerization being carried out in the presence of the product from Step 1 so that the crosslinked (meth)acrylate and crosslinked styrene-acrylonitrile components form an interpolymer wherein the respective phases surround and penetrate one another; and 3. either emulsion or suspension polymerizing a monomer charge of styrene and acrylonitrile, in the absence of a crosslinking agent, in the presence of the product resulting from Step 2. If desired, Steps 1 and 2 can be reversed in the above described procedure. This product, which is used as the predominant ingredient in the blend of the present invention, comprises from about 5% to about 50%, by weight, of at least one of the above-identified crosslinked (meth)acrylates, from about 5% to about 35%, by weight, of the crosslinked styrene-acrylonitrile component, and from about 1596 to about 90%, by weight, of the uncrosslinked styrene-acrylonitrile component. It contains little graft polymerization between the styrene-acrylonitrile copolymer segments and the crosslinked (meth)acrylate polymeric component, and it has an optimum processing range of from about 1990C. to about 232.20C. The particular optimum temperature will depend upon the precise amount of each of the three differing polymer phases which are present in the composition. Further details regarding this type of polymer composition can be found in U.S. Patent No. 3,944,631 to A. J. Yu et al., which is incorporated herein by reference. The terminology "vinyl chloride polymer", as used herein, is meant to encompass polyvinyl chloride homopolymers, as well as the copolymers of vinyl chloride with comonomers polymerizable therewith, with the former monomer predominating the latter in amount. Such comonomers include vinyl esters of carboxylic acids, such as vinyl acetate, the C,-C20 alkyl esters of acrylic and methacrylic acid, the aryl, halo- and nitro-substituted benzyl esters of acrylic and methacrylic acid, the ethylenically unsaturated mono- and dicarboxylic acids, and the like. The term "acrylic resin", as used herein, is intended to encompass those acrylic resins which are made by the polymerization of acrylic ester monomers. Details regarding the structure of these polymeric materials as well as the processes for forming them are available from a number of sources including Modern Plastics Encyclopedia (1977-1978 Edition) pp. 9-10; Handbook of Plastics and Elastomers, C. A. Harper ed., McGraw-Hill, Inc. 1975, pp. 1-71 to 1-75; and Polymers and Resins by B. Golding, Van Nostrand Co., 1959, pp. 448-462. Representative polymers which are included in this class of acrylic resins or plastics include: polymethyl methacrylate, polyethyl acrylate and polybutyl acrylate. Copolymers of these acrylic esters with minor amounts of one or more polymerizable monomers are also intended to be encompassed, e.g., the copolymer of methyl methacrylate with styrene and acrylonitrile. Commercially available acrylic resins include those sold under the following trademarks: LUCITE (E.I. duPont de Nemours and Co.); and PLEXIGLAS (Rohm and Haas Co.). The respective weight amounts of the three abovedescribed components of the blends of this invention can be varied within the following weight percentages (based on the weight of the entire blend): interpolymers - from about 45% to about 65%; vinyl chloride polymer - from about 20% to about 35%; and acrylic resin - from about 15% to about 30%. Preferred blends generally will comprise from about 45% to about 50%, by weight, of the interpolymer, from about 30% to about 35%, by weight of the vinyl chloride polymer, and from about 20% to about 25%, by weight of the acrylic resin. The blends of the present invention have better flame retardancy and impact resistance than blends of the interpolymer and acrylic resin and have better surface gloss and heat distortion temperature than blends of the interpolymer and vinyl chloride polymer. In addition to the three aforementioned components, the compositions of the present invention can contain other additives, which enhance specific desired properties of the compositions. Representative additives include heat and light stabilizers, antioxidants, fillers (e.g., calcium carbonate, clay, etc.), lubricants, additional impact modifiers, additional flame retardant and/or smoke suppressant additives (e.g., antimony oxide, aluminum trihydrate, etc.), and pigments (e.g., titanium dioxide, carbon black, etc.). The blends of this invention can be formulated from the components thereof by any of the commonly used compounding techniques including single or twin screw extrusion, two-roll or Banbury milling, and the like. Shapes or articles can be fabricated from the compounded blends by extrusion, calendering, injection molding, or any other fabrication method which is suitable for thermoplastic resins. Mixtures of the components of the blends may also be fabricated directly into shapes or articles by any method which will suitably compound them in the course of fabrication. The present invention will be further understood by examination of the following Examples which illustrate certain embodiments of the present invention. EXAMPLE 1 This Example illustrates the physical property profile for certain compositions including a composition in accordance with the present invention. An interpolymer modifier composition was formed by blending, at 850C. for 10 min. in a WELEX high intensity blender, 10,000 gm. of interpolymer (32% crosslinked polybutyl acrylate, 10% crosslinked styreneacrylonitrile, and 58% uncross linked styrene-acrylonitrile as described in U.S. Patent No. 3,944,631 to A. J. Yu et al.), 10 gm. of tincarboxylate stabilizer (T-340 brand from Carstab Chemicals), and 50 gm. of polyethylene lubricant (AC-392 brand from Allied Chemical Company). This composition will be referred to as "interpolymer powder" in this Example. Various compositions were extruded as indicated in the following Table for later testing. Composition D is in accordance with the present invention and comprises 50 wt. % interpolymer, 25 wt. % polymethyl methacrylate, 25 wt. % polyvinyl chloride. EXAMPLE 1 (cont'd.) Extrusion Temp. Composition Amount ( C.) A: Interpolymer Powder 9.98 kg. 193-204 B: Interpolymer Powder: PMMA Pellets (50:50) 6.81 kg. 204-215 C: Interpolymer Powder: PVC powder (50:50) 10.43 kg. 176-193 D: Interpolymer Powder: PVC Pellets (50:50) and Interpolymer Powder: PMMA Pellets (50:50) 23.13 kg. 193-204 PMMA = polymethyl methacrylate (LUCITE 147K brand). PVC = polyvinyl chloride (GEON 103 EPF-76 brand), a suspension resin designed for exterior profiles. The PVC powder used in C comprised 100 parts by weight PVC, 2.0 parts tin mercaptide stabilizer (THERMOLITE 137 brand), 0.5 part paraffin wax (HOECHST XL 165 brand), 0.3 part polyethylene lubricant (ALLIED A 629a brand), and 1.0 calcium stearate. The extruded samples were dried at about 800C. for over two hours before injection molding. The Table given below sets forth the physical properties noted. The values given below are the average of tests on five specimens with the value in parenthesis being the standard deviation of the data: EXAMPLE 1 (cont'd.) Tensile Tensile Strength Elongation Mod. of (MPa) (%) Elast. Sample Yield Break Yield Break (GPa) A 36.04 25.50 4 43.6 1.37 (0.15) (0.74) (0.4) (6.3) (0.11) B 57.77 39.80 4.7 42.3 2.29 (0.39) (1.23) (0.6) (11.8) (0.46) C 44.14 32.94 4.4 71.5** 1.82 (0.18) (0.94) (0.5) (26.4) (0.35) 51.59 36.31 5 54.3 1.67 (0.63) (0.50) (0.7) (8.2) (0.21) * present invention. ** two specimens did break at values over 100% which was beyond the capability of the instrument. The value given is the average value of the remaining three specimens. The following additional data were also generated. The numbers after "+" give the 95% confidence limits for the data: Flexural Modulus SAMPLE of Elasticity (GPa) A 1.69 +0.08 B 2.58 +0.20 C 2.26 +0.12 D* 2.36 +0.04 * present invention EXAMPLE 1 (cont'd.) One specimen each of Samples A-D was tested for its heat distortion temperature both before and after being annealed at 900C. for 2 hours. The following values were obtained: Unannealed Annealed Sample (Oc.) ( C.) A 74 94 B 74 92 C 68 80 D* 72 89 * present invention The above data indicate that for sample D the heat deflection temperature is synergistic, being more than the average of the values for samples B and C. The following IZOD impact data was recorded on ten specimens. The abbreviation "G" under the heading "Sample" represents that the testing was done on the side of the specimen adjacent the gate of the injection molding specimen, whereas "V" represents the testing was done on the side adjacent the vent of the specimen. The pendulum capacity was 107 J/m, except for sample C where it was 267 J/m. The 95% confidence limits are given after the "t" sign. EXAMPLE 1 (cont'd.) IZOD Impact Type of Break SAMPLE (J/m) Brittle Ductile A-G 481 + 32 0 10 A-V 166 t 21 0 10 B-G 32 + 5 10 0 B-V 27 t 5 10 0 C-G 870 t 27 0 10 C-V 785 + 32 0 10 D*-G 75 + 5 10 0 D*-V 85 + 5 10 0 * present invention EXAMPLE 2 This Example illustrates the admixture, as appropriate, of suitable amounts of: (1) interpolymer/PVC blends; (2) interpolymer/polymethyl-methacrylate blends; (3) interpolymer; and (4) polymethyl methacrylate to yield blends of varying amount of interpolymer, polyvinyl chloride, and polymethyl methacrylate in accordance with the present invention. The compositions and procedures employed in Example 1 were used. The Table given below sets forth the average IZOD impact values for ten specimens of each sample. Interpolymer PVC PMMA IZOD Impact* Sample (parts by Weight) (J/m) A 50 25 25 80 B B 50 20 30 91 B C 50 30 20 240 D D 55 25 20 176 B E 55 20 25 139 B F 60 20 20 166 B G 45 25 30 85 B H 45 30 25 192 B I 45 35 20 336 D * determined on 3.18 mm. thick plaques. "B" indicates break; "D", ductile. The data illustrate that for the best IZOD values the composition should contain less than about 25 parts by weight PMMA (acrylic resin), and the composition should contain over 25 parts by weight PVC. The preceding Examples illustrate certain embodiments of the present invention and should not be construed in a limiting manner. The scope of protection that is sought is set forth in the claims which follow.

Claims: What is Claitned: 1. A fire retardant blend having good impact resistance and a high heat deflection temperature comprising: (1) a predominant amount of an interpolymer comprising: (a) crosslinked (meth)acrylate; (b) crosslinked styrene-acrylonitrile; and (c) uncrosslinked styrene acrylonitrile components; (2) an acrylic resin; and (3) a vinyl chloride polymer. 2. A blend as claimed in Claim 1 wherein the interpolymer comprises from about 5% to about 50%, by weight of the crosslinked (meth)acrylate component, from about 5% to about 35% by weight of the crosslinked styrene-acrylonitrile component, and from about 15% to about 90% by weight of the uncrosslinked styrene acrylonitrile component. 3. A blend as claimed in Claim 1 which comprises from about 45% to about 65%, by weight, of the interpolymer, from about 20% to about 35%, by weight of the vinyl chloride polymer, and from about 15% to about 30% by weight of the acrylic resin. 4. A blend as claimed in Claim 1 which comprises from about 45% to about 50%, by weight, of the interpolymer, from about 30% to about 35%, by weight of the vinyl chloride polymer, and from about 20% to about 25% by weight of the acrylic resin. 5. A blend as claimed in Claim 2 which comprises from about 45% to about 65%, by weight, of the interpolymer, from about 20% to about 35%, by weight of the vinyl chloride polymer, and from about 15% to about 30% by weight of the acrylic resin. 6. A blend as claimed in Claim 2 which comprises from about 45% to about 50%, by weight, of the interpolymer, from about 30% to about 35%, by weight of the vinyl chloride polymer, and from about 20% to about 25% by weight of the acrylic resin. 7. A blend as claimed in either Claim 1 or 2 which contains no more than about 25 parts by weight acrylic resin and over 25 parts by weight vinyl chloride polymer per 100 parts by weight of the blend. 8. A blend as claimed in either Claim 1, 2, 3, 4, 5, or 6 in which the acrylic resin is polymethyl methacrylate. 9. A blend as claimed in either Claim 1 or 2 which contains less than about 25 parts by weight polymethyl methacrylate and over 25 parts by weight vinyl chloride polymer per 100 parts by weight of the blend.

Inventors: ALIBERTO, ANTHONY CARMINE, SILBERBERG, JOSEPH
Applicants: GENERAL ELECTRIC COMPANY
Application year: 1983
Main classification: C08L51
IPC codes: C08L27, C08L33, C08L1, C08L25, C08L51