Unsaturated polyester resins containing cellulose ester and molded articles therefrom

Abstract

This invention provides a liquid, polymerizable composition of matter, suitable for molding fibrous reinforced articles with exceptionally smooth surfaces, said composition being curable under heat and pressure to form a rigid, cured product which is characterized by an optically heterogeneous appearance. The composition comprises a thermoplastic cellulose ester, and α,β-ethylenically unsaturated polymerizable polyester having a molecular weight per double bond factor of 150 to 186, and a monomer containing a CH 2 ═C< group copolymerizable with the unsaturated polyester.

What is claimed is: 
     
       1. A liquid, polymerizable composition of matter, suitable for molding fibrous reinforced articles with a smooth surface, said composition being curable under heat and pressure to form a rigid, cured product which is characterized by an optically heterogeneous appearance, comprising per 100 parts by weight (a) 20 to 70 parts of an α,β-ethylenically unsaturated polymerizable polyester having a molecular weight per double bond factor of 150 to 186, said polyester prepared by condensation of one or more α,β-ethylenically unsaturated dicarboxylic acids with one or more dihydric alcohols,   (b) 25 to 75 parts of a monomer containing a CH 2  ═C< group copolymerizable with said unsaturated polyester, and   (c) 1 to 25 parts of a cellulose ester that, when present during the copolymerization of (a) and (b), yields an optically heterogeneous cured composition, the sum total of (a), (b) and (c) being 100 parts by weight.   
     
     
       2. The liquid, polymerizable composition of matter, of claim 1 wherein the cellulose ester (c) is soluble in monomer (b) or in a solution of unsaturated polyester (a) in monomer (b). 
     
     
       3. The liquid, polymerizable composition of matter, of claim 1 wherein at least 25 percent by weight of the ester groups of cellulose ester (c) contain 4 to 6 carbon atoms. 
     
     
       4. The liquid, polymerizable composition of matter, of claim 1 wherein cellulose ester (c) is cellulose acetate butyrate. 
     
     
       5. The liquid, polymerizable composition of matter, of claim 4 wherein the ester groups of the cellulose acetate butyrate are at least 25 percent butyryl. 
     
     
       6. A liquid, polymerizable composition of matter, according to claim 1 which, upon curing, undergoes a volumetric change within the range of 10 percent expansion by volume to 5 percent shrinkage by volume. 
     
     
       7. A liquid, polymerizable composition of matter, according to claim 1 wherein the unsaturated polymerizable polyester is a condensation product of an α,β-ethylenically unsaturated dicarboxylic acid with a dihydric alcohol. 
     
     
       8. A liquid, polymerizable composition of matter, according to claim 7 wherein a minor proportion of the unsaturated acid is replaced by a saturated dicarboxylic acid selected from the group consisting of ortho-phthalic acid, isophthalic acid, terephthalic acid, succinic acid, sebacic acid, adipic and methylsuccinic acids. 
     
     
       9. A liquid, polymerizable composition of matter, according to claim 8 wherein the unsaturated dicarboxylic acid is selected from the group consisting of maleic and fumaric acids and the dihydric alcohol is selected from the group consisting of propylene glycol, 1,3-butanediol, diethylene glycol, a mixture of ethylene and propylene glycol containing at least 50 mole percent propylene glycol and a mixture of propylene glycol and dipropylene glycol containing at least 50 mole percent propylene glycol. 
     
     
       10. A liquid, polymerizable composition of matter, according to claim 1 wherein the unsaturated polymerizable polyester (a) is the condensation product of propylene glycol and maleic anhydride, the monomer (b) is styrene and the thermoplastic (c) is cellulose acetate butyrate. 
     
     
       11. The rigid, cured product of the composition of claim 1. 
     
     
       12. The rigid, cured product of the composition of claim 10. 
     
     
       13. A rigid, smooth-surfaced article, containing fibrous glass reinforcement and crosslinked, polymerized mass obtained by curing under heat and pressure a mixture comprising for each 100 parts by weight (a) 20 to 70 parts of an α,β-ethylenically unsaturated polymerizable polyester having a molecular weight per double bond factor of 150 to 186, said polyester prepared by condensation of one or more α,β-ethylenically unsaturated dicarboxylic acids with one or more dihydric alcohols,   (b) 25 to 75 parts of a monomer containing a   CH.sub.2 ═C<     group copolymerizable with said unsaturated polyester and     (c) 1 to 25 parts of a cellulose ester which is soluble in monomer (b) or a solution of unsaturated polyester (a) in monomer (b), but which, when present during the copolymerization of (a) and (b), yields an optically heterogeneous cured composition, the sum total of (a), (b) and (c) being 100 parts by weight.   
     
     
       14. An article according to claim 13, in which the fibrous glass reinforcement is present in an amount of from 5 to 70 percent by weight of the total weight of the article. 
     
     
       15. An article according to claim 14, in which there is also present an inert, inorganic filler. 
     
     
       16. A method of producing a fibrous reinforced article with smooth surfaces which comprises providing a liquid, polymerizable composition of matter comprising (a) 20 to 70 parts by weight of an α,β-ethylenically unsaturated polymerizable polyester having a molecular weight per double bond 150 of 150 to 86, said polyester prepared by condensation of one or more α,β-ethylenically unsaturated dicarboxylic acids with one or more dihydric alcohols,   (b) 25 to 75 parts by weight of a monomer containing a CH 2  ═C< group copolymerizable with said unsaturated polyester and   (c) 1 to 25 parts by weight of a cellulose ester and molding and curing said polymerizable composition of matter in the presence of fibrous reinforcement under heat and pressure, the sum total of (a), (b) and (c) being 100 parts by weight.   
     
     
       17. The method of claim 16, wherein the fibrous reinforcement is a glass material. 
     
     
       18. A method according to claim 17 wherein there is also present an inert, inorganic filler. 
     
     
       19. A liquid, polymerizable composition of matter, suitable for molding glass fibrous reinforced articles with a smooth surface, said composition being curable under heat and pressure to form a rigid, cured product which is characterized by an optically heterogeneous appearance, comprising per 100 parts by weight (a) 30 to 50 parts of α,β-ethylenically unsaturated polymerizable polyester having a molecular weight per double bond factor of 150 to 186, and   (b) 40 to 60 parts of a monomer containing a   CH.sub.2 ═C<     group copolymerizable with said unsaturated polyester and     (c) 5 to 20 parts of a cellulose ester which is soluble in monomer (b), or in a solution of unsaturated polyester (a) in monomer (b), but which, when present during the copolymerization of (a) and (b), yields an optically heterogeneous cured composition, the sum total of (a), (b) and (c) being 100 parts by weight.   
     
     
       20. A liquid, polymerizable composition of matter according to claim 19 wherein the unsaturated polymerizable polyester is (a) the condensation product of propylene glycol and maleic anhydride, the monomer   (b) is styrene and the thermoplastic polymer   (c) is cellulose acetate butyrate.   
     
     
       21. A liquid, polymerizable composition of matter according to claim 1, wherein the α,β-ethylenically unsaturated polyester (a) is the condensation product of unsaturated dicarboxylic acids chosen from the group consisting of maleic and fumaric acids and the dihydric alcohol is propylene glycol with up to 50 mole percent replaced by another diol. .Iadd. 
     
     
       22.  A homogeneous polyester resin system which comprises per 100 parts by weight about 1 to about 25 parts by weight of a cellulose organic ester and selected from the group consisting of cellulose propionate, cellulose acetate propionate, and cellulose acetate butyrate; from about 25 to about 75 parts by weight of a monomeric copolymerizable component containing a CH 2  ═C< group; and from about 20 to about 70 parts by weight of an unsaturated polyester resin component having a molecular weight to double bond factor of 150 to 186, said unsaturated polyester resin being the condensation product obtained by polycondensation of α,β-unsaturated dicarboxylic acid and/or anhydrides together with polyhydric alcohol. .Iaddend..Iadd. 
     
     
       23.  The resin system of claim 22 wherein the monomeric copolymerizable component is styrene. .Iaddend..Iadd. 
     
     
       24.  The resin system of claim 22 having therein an effective amount of a polymerization initiator whereby upon curing of the resinous system, surfaces are characterized as smooth, free of ripple and shrink marks, with excellent adhesion to paints. .Iaddend..Iadd. 
     
     
       25.  The resin system of claim 22 wherein the α,β-unsaturated dicarboxylic acid is selected from the group consisting of maleic acid, maleic anhydride, fumaric acids and citraconic acid. .Iaddend..Iadd. 26. The resin system of claim 22 wherein the polyhydric alcohol is selected from the group consisting of ethylene glycol; propanediol-1,2; butanediol-1,3; diethylene glycol and dipropylene glycol. .Iaddend..Iadd. 
     
     
         7.  A cured product cured by exposing the resin system of claim 22 to a temperature from about 212° F. to about 350° F. and 
     
     
        pressures in the range of from 100 to 1,500 psi. .Iaddend..Iadd. 28.  A method for preparation of a homogeneous polyester resin system which comprises mixing together per 100 parts by weight about 1 to about 25 parts by weight of a cellulose organic ester selected from the group consisting of cellulose propionate, cellulose acetate propionate, and cellulose acetate butyrate; which is added with agitation to about 25 to about 75 parts by weight of a monomeric copolymerizable component containing a CH 2  =C< group; and thereafter, adding from about 20 to about 70 parts by weight of unsaturated polyester resin, the unsaturated polyester resin having a molecular weight to double bond factor of 150 to 186 and being the condensation product obtained by polycondensation of α,β -unsaturated dicarboxylic acid and/or anhydrides together 
     
     
        with polyhydric alcohol. .Iaddend..Iadd. 29.  The method of claim 28 wherein the monomeric copolymerizable component is styrene. 
     
     
        .Iaddend..Iadd. 30.  The method for preparation of a resin system of claim 28 wherein the α,β-unsaturated dicarboxylic acid is selected from the group consisting of maleic acid, maleic anhydride, fumaric acids, 
     
     
        and citraconic acid. .Iaddend..Iadd. 31.  The method for preparation of a resin system of claim 28 wherein the polyhydric alcohol is selected from the group consisting of ethylene glycol; propanediol-1,2; butanediol-1,3; diethylene glycol and dipropylene glycol. .Iaddend.