MOLDABLE COMPOSITIONS HAVING IMPROVED SURFACE GLOSS

Abstract: Moldable compositions which comprise a high molecu­ lar weight nonequimolar copolymer of an ethylenically unsaturated dicarboxylic acid or its derivative, and at least one copolymerizable monomer and, a surface gloss enhanc­ ing agent selected from the group consisting of amides or N,N-dimethylamides of linear and saturated or unsaturated fatty acids containing 16 or more carbon atoms and low molecular weight copolymers of styrene and maleic anhyd­ ride, facilitate the production of molded articles exhibiting improved surface gloss.

Description: This invention relates to moldable compositions. More specifically, this invention relates to surface gloss enhancing agents for moldable compositions comprising high molecular weight non-equimolar copolymers of ethylenically unsatured dicarboxylic acids, or their derivatives, and at least one copolymerisable monomer. High molecular weight non-equimolar copolymers of ethylenically unsaturated dicarboxylic acids, or their derivatives, and at least one copolymerisable monomer, such as, for example, non-equimolar copolymers of styrene and maleic anhydride are widely used in molding compositions to produce injection molded parts. Such molded parts typically exhibit low surface gloss and, accordingly, the compositions are not suitable for use in applications in which high surface gloss is a needed property: High surface gloss, for example, is critical in hand tool housings, lighting fixtures and cosmetic kits. The present invention provides agents which, when employed in moldable compositions which comprise high molecular weight non-equimolar copolymers of ethylenically unsaturated dicarboxylic acids, or their derivatives, and at least one copolymerisable monomer, serve to increase the surface gloss of the resulting molded article. As used herein, the term "high molecular weight" means a molecular weight of 100,000 or more and the term "low molecular weight" means a molecular weight of 5,000 or less. US-A-4408010 describes a polyblend of (a) a styrene/maleimide copolymer obtained by the method described, for example, in J. Macromol. Sci. Chem. All(s), pages 267-286 (1977) and having a number average molecular weight of 120,000 measured by GPC and (b) a non-equimolar high molecular weight copolymer of styrene and maleic anhydride. According to this invention, there is provided a moldable composition comprising a high molecular weight molding grade non-equimolar copolymer of less than 50 mole % of an ethylenically unsaturated dicarboxylic acid moiety selected from ethylenically unsaturated dicarboxylic acids and anhydrides, imides, substituted imides, half esters and acid amides of said acids or mixtures thereof and more than 50 mole % of at least one comonomer which is polymerisable therewith and is selected from monovinyl aryl monomers, unsaturated nitriles and acrylic monomers or mixtures thereof, said copolymer having a molecular weight of at least 100,000, characterised in that said composition also includes a surface gloss enhancing agent selected from copolymers of styrene and maleic anhydride having a molecular weight not greater than 5,000, the amount of surface gloss enhancing agent employing being sufficient to enhance the surface gloss of the resulting molded composition as compared to the surface gloss of the molded composition in the absence of the surface gloss enhancing agent. Suitable acids and their derivatives useful in the present invention are maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, ethyl maleic acid, methyl itaconic acid, chloromaleic acid, dichlormaleic acid, bromomaleic acid, dibromomaleic acid and phenylmaleic acid, the anhydrides of these acids, the imides of these acids and their N-substituted derivatives, the acid amide derivatives, or the half esters of these with suitable alcohols. The alcohols used may be the primary and secondary alkanols containing up to 6 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, and n-pentyl alcohol; halogenated alkanols having up to 6 carbon atoms, such as 2,3-dichloro-1-propanol, and 2-bromo-1-propanol; arylalkyl alcohols, such as benzyl alcohol; cyclic alcohols having up to 6 carbon atoms, such as cyclopentanol, cyclohexanol and tetrahydrofurfuryl alcohol; ether alcohols, such as 2-butoxyethanol and the ethyl ether of diethylene glycol. The imide derivatives may be prepared by reacting!he starting anhydride or diacid copolymers with aqueous ammonia, ammonia or amines. Suitable amines are the alkyl amines having 1 to 4 carbon atoms, such as methylamine, ethylamine, propylamine, isopropylamine and butylamine; ethanolamine; aniline, benzylamine; allylamine. Also suitable are the water soluble α,ω-alkylenediamines having 2 to 6 carbon atoms in the alkylene group, such as ethylenediamine, and hexamethylenediamine. Arylene diamines, such as the phenylene diamines and benzidines may also be used. The diamines are useful for preparing copolymers having varying degrees of crosslinking. These diamines may be used alone or in combination with other monoamines to vary the degree of crosslinking. The copolymerizable monomers may be vinyl aryl monomers, such as styrene, alpha-methylstyrene, nuclear methylstyrenes, ethylstyrene, isopropylstyrene, tert-butylstyrene, chlorostyrenes, dichlorostyrenes, vinylnaphthalene; unsaturated nitriles, such as acrylonitrile and methacrylonitrile; and acrylic monomers, such as acrylic acid, methacrylic acid, methyl acrylate and methyl methacrylate. Mixtures of two or more of these copolymerizable monomers may be used if desired. The high molecular weight non-equimolar copolymers may be prepared by any of the several methods available for the preparation of non-equimolar copolymers. Thus, these copolymers may be prepared by solution polymerization directly from the respective monomers by the incremental addition of the reactive monomer as taught by U.S.-A-2,971,939; by a continuous recycle polymerization process such as described in U.S.-A-2,769,804 and 2,989,517; or by the suspension polymerization process described in U.S.-A-3,509, 110. The high molecular weight molding grade non-equimolar copolymers as described above can be impact modified using any art-recognized method of incorporating the impact modifier, which modifier is, typically, at least one copolymer or homopolymer rubber or mixtures thereof. Preferably, the impact modifers are incorporated into the monomer mixture prior to polymerization using for example any of the methods of U.S.-A-4,097,551. Any soluble high molecular weight molding grade non-equimolar copolymer can be employed to produce the molding compositions of this invention. Particularly suitable for use are the high molecular weight non-equimolar copolymers of styrene and maleic anhydride designated Dylark® copolymers, commercially available from ARCD Chemical Company, division of Atlantic Richfield Company. Suitable Dylark copolymers include those of the Dylark 200 series of copolymers, the Dylark 300 series of copolymers and Dylark 700 copolymer. Of these Dylark copolymers, Dylark 250, Dylark 350 and Dylark 700 are rubber-modified, as described above and are particularly suitable for use in the molding compositions of this invention. Particularly suitable low molecular weight copolymers of styrene and maleic anhydride suitable for use as surface gloss enhancing agents are also commercially available from ARCD Chemical Company under the designation SMA® Resins, such as, for example, SMA® Resin 1000, SMA® Resin 2000, and SMA® Resin 3000. Methods for the manufacture of these SMA® Resins are taught in U.S.-AA-3,388,106; 3,418,292; 3,178,395; 3,085,986; 3,085,994; 3,342,787; 3,392,155; 3,451,979; 3,245,933; 3,046,246 and 3,245,933. SMA® Resin 1000 has a styrene to maleic anhydride ratio of 1/1 and a molecular of about 1600. SMA® Resin 2000 has a styrene to maleic anhydride ratio of 2/1 and a molecular of about 1700. SMA® Resin 3000 has a styrene to maleic anhydride ratio of 3/1 and a molecular of about 1900. The moldable compositions of this invention can also include other ingredients, such as flame retardants, extenders, processing aids, pigments, stabilizers and the like, for their conventionally employed purposes. Reinforcing fillers, in amounts sufficient to impart reinforcement, can be used, such as aluminum, iron or nickel, and the like, and non-metals, such as carbon filaments, silicates, such as acicular calcium silicate, asbestos, titanium dioxide, potassium titanate and titanate whiskers, glass flakes and fibers. The moldable compositions can be prepared using any conventional method which will result in an essentially homogeneous mixture of non-equimolar copolymer and surface gloss enhancing agent such as, for example, compounding rolls, mixing extruders, Banbury mixers and the like. Preferably, the non-equimolar copolymer is prepared and the surface gloss enhancing agent is added to the copolymer as it is pumped out of the polymerization reactor and into an extruder. Typically, the surface gloss enhancing agent will be employed in an amount within the range of from about 0.5 to about 10 weight percent of the molding composition. The present invention is further illustrated by the following examples, set forth in the following Table, which examples are not to be construed as limiting. The above data indicate the marked improvement in surface gloss achieved by the molding compositions of this invention when employed to produce molded articles.

Claims: A moldable composition comprising a high molecular weight molding grade non-equimolar copolymer of less than 50 mole % of an ethylenically unsaturated dicarboxylic acid moiety selected from ethylenically unsaturated dicarboxylic acids and anhydrides, imides, substituted imides, half esters and acid amides of said acids or mixtures thereof and more than 50 mole % of at least one comonomer which is polymerisable therewith and is selected from monovinyl aryl monomers, unsaturated nitriles and acrylic monomers or mixtures thereof, said copolymer having a molecular weight of at least 100,000, characterised in that said composition also includes a surface gloss enhancing agent selected from copolymers of styrene and maleic anhydride having a molecular weight not greater than 5,000, the amount of surface gloss enhancing agent employing being sufficient to enhance the surface gloss of the resulting molded composition as compared to the surface gloss of the molded composition in the absence of the surface gloss enhancing agent. A moldable composition as claimed in claim 1 characterised in that said high molecular weight molding grade non-equimolar copolymer is a styrene-maleic anhydride copolymer. A moldable composition as claimed in claim 2 characterised in that said styrene-maleic anhydride copolymer is impact modified. A moldable composition as claimed in claim 2 or claim 3 characterised in that the composition further includes a filler. A moldable composition as claimed in any one of claims 1 to 4 characterised in that said surface gloss enhancing agent is employed in an amount within the range of from about 0.5 to about 10 weight percent of the moldable composition.

Inventors: FRANCIS, PETER S.
Applicants: ARCO CHEMICAL TECHNOLOGY INC.
Application year: 1984
Main classification: C08L35
IPC codes: C08K5