POLYURETHANE OLIGOMER IMPACT AND SHRINKAGE MODIFIERS FOR THERMOSET POLYESTERS

Abstract: The polyurethane oligomer reaction product of a hyd­ roxyl-terminated prepolymer with a dicarboxylic acid anhyd­ ride is incorporated into conventional thermosetting polyes­ ter resin formulations to impart improved impact properties and reduced shrinkage behaviour.

Description: POLYURETHANE OLIGOMER IMPACT AND SHRINKAGE MODIFIERS FOR THERMOSET POLYESTERS This invention relates to a thermosetting polyester resin composition; and, more particularly, to a thermosetting polyester resin composition which includes a select polyurethane oligomer to improve impact properties and surface characteristics. The invention also extends to the oligomers themselves,processes for preparing the thermoset compositions and the thermoset compositions so prepared. In recent years, there has been a steady increase in the use of reinforced plastic materials for exterior components in automotive construction. Further increases in the utilization of plastics can be expected as automobile manufacturers continue to strive to meet vehicle weight reduction goals. In the area of rigid plastic automotive components, fiberglass reinforced thermosetting polyester resins have been extensively employed. This can be attributed to their overall physical capabilities (e.g., dimensional stability, strength, high temperature resistance and paint adhesion). Other advantages include facility of handling and machining. However, these polyester systems still present certain deficiencies such as a brittle nature, which can lead to severe impact and fatigue problems. There is also a need to improve surface characteristics and shrinkage control. To overcome these problems various additives have been introduced into polyester sheet molding compounds (SMC) and bulk molding compounds (BMC). For example, in U.S. Patent No. 4,020,036 issued to Aubrey South, Jr. on April 26, 1977, liquid polymers, such as polybutadiene, are added in order to toughen polyester products. However, since these materials are not inherently compatible with polyester, these additives cannot be added t6 the polyester until it is time to mix the resin with the fiberglass. Saturated diacids or long-chain glycols also have been used in preparing polyester resins; the resulting products have been flexibilized, but, at the cost of lower mechanical and thermal properties. Another approach involves the introduction of urethane systems into polyester resins. In U.S. Patent No. 4,062,826 issued to Francis Gowland Hutchinson et al. on December 13, 1977,precursors of a cross-linked polyurethane are polymerized within a mixture of ethylenically unsaturated polyester and vinyl monomer to form a product with an interpenetrating polyurethane gel network within the polyester cross-linked structure. While higher impact properties are reported to be achieved, the fine surface finish required for automotive body part applications is not accomplished. See Forger, G., Toughened SMC, Plastics World, page 63 (June 1978). Thus, there is a need in the art for an improved additive for polyester resin systems which will impart high impact properties and low shrink characteristics. Now, according to the invention, it has been discovered that these requirements can be achieved by incorporating a unique polyurethane oligomer system into a conventional thermosetting polyester resin formulation. Using such an oligomer system a molded plastic product may be produced which has enhanced impact properties as well as low shrinkage to ensure satisfactory surface characteristics. Preferred embodiments and features of the invention will now be described. The polyurethane chemical system employed according to the present invention is formed by the reaction of a hydroxyl terminated prepolymer with a dicarboxylic acid anhydride. Generally, the resulting oligomers of controlled molecular weight are readily miscible with polyester resins and hence do not present pre-mix incompatibility storage problems. When the polyurethane oligomer-polyester resin system is processed and moulded, upon curing the molded product, the oligomers seem to phase out and form separate pockets or centers within the thermoset polyester matrix. The inclusion of the flexible polyurethane oligomer accomplishes a significant improvement in impact properties. Moreover, the unique behavior of the oligomers during polyester cure tends to relieve strain and thus prevent shrinkage and accompanying surface defects. The polyurethane oligomer is prepared by first reacting an organic polyisocyanate with a polyol in an equivalent ratio of NCO/OH from about 0.3/1 to about 0.99/1, using standard procedures, to yield a hydroxyl-terminated prepolymer of controlled molecular weight. Preferably, the NCO/OH ratio ranges from about 0.60/1 to about 0.99/1. Common urethane catalysts, e.g. tertiary amines and metal compounds such as stannous octoate, dibutyltin dilaurate or dibutyl di (lauryl mercapto) tin maybe used to accelerate the reaction. In forming the prepolymer, other ingredients, such as chain extenders, well known to those in the polyurethane art, also may be included in the reaction mixture. These chain extenders include low molecular weight glycols such as ethylene glycol, butane diol, hexane diol, propylene glycol, bisphenol A, and the like. The polyol reactant used in the prepolymer formation includes polyether polyols and polyester polyols and mixtures of two or more such compounds. The polyol, or mixture of polyols, should have an average molecular weight ranging from about 300 to about 10,000. Preferably, the average molecular weight is about 500 to about 6,500. The average functionality of the polyol or polyol blend is usually about 2 to about 6, and preferably about 2 to about 3. Polyester polyols are the preferred polyol reactant. Suitable polyester polyols include the products of reacting polycarboxylic acids with polyhydric alcohols. Illustrative polycarboxylic acids include, for example, oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, phthalic and isophthalic acids, mixtures thereof, and the like. Illustrative polyhydric alcohols include various diols, triols, tetrols and higher functionality alcohols, such as ethylene glycol, diethylene glycol1 1,3propylene glycol, 1,2-propylene glycol, butylene glycols, butane diols, pentane diols, glycerol, trimethylolpropane, trimethylolhexane,-pentaerythritol, sorbitol, hexane 1,2,6-triol, 2-methyl glucoside, mixtures thereof, and the like. Suitable polyether polyols include various polyoxyalkylene polyols and mixtures thereof. These can be prepared, according to well-known methods, by condensing an alkylene oxide, or a mixture of alkylene oxides using random or step-wise addition, with a polyhydric initiator or a mixture of polyhydric initiators. Illustrative alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, amylene oxide, aralkylene oxides such as styrene oxide, and the halogenated alkylene oxides such as trichlorobutylene oxide and so forth. The most preferred alkylene oxide is propylene oxide or a mixture thereof with ethylene oxide using random or step-wise oxyalkylation. The polyhydric initiator used in preparing the polyether polyol reactant includes the following and mixtures thereof: (a) the aliphatic diols such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, butylene glycols, butane diols, pentane diols, and the like; (b) the aliphatic triols such as glycerol, trimethylolpropane, triethylolpropane, trimethylolhexane, and the like; (c) higher functionality alcohols such as sorbitol, pentaerythritol, methyl glucoside, and the like; (d) the pqlyamines such as tetraethylene diamine; and (e) the alkanolamines such as diethanolamine, triethanolamine, and the like. A preferred group of polyhydric initiators for use in preparing the polyether polyol reactant is one which comprises aliphatic diols and triols such as ethylene glycol, propylene glycol, glycerol, trimethylolpropane, and the like. The alkylene oxide-polyhydric initiator condensation reaction is preferably carried out in the presence of a catalyst such as KOH as is well known in the art. In effecting the reaction, a sufficient proportion of alkylene oxide is used as to provide a final polyol product having an average molecular weight of about 300 to about 10,000, preferably about 500 to about 6,500, and more preferably about 2,000 to about 4,000. The catalyst is thereafter preferably removed, leaving a polyether polyol which is ready for use in preparing the hydroxyl-terminated prepolymer of the invention. Any suitable organic polyisocyanate, or mixture df polyisocyanates, may be used in the polyurethane prepolymer formation including toluene diisocyanate, such as the 80:20 and the 65:35 mixtures of the 2,4and 2,6-isomeric forms, ethylene diisocyanate, propylene diisocyanate, methylene-bis (4-phenyl isocyanate), methylene-bis (4-cyclohexyl) isocyanate, xylene diisocyanate, 3,3'-bitoluene-4,4'-diisocyanate, hexamethylene diisocyanate, naphthalene 1,5-diiso-- cyanate, isophorone diisocyanate, the polymeric isocyanates such as polyphenylene polymethylene isocyanate, and the like, and mixtures thereof. In accordance with a particularly preferred embodiment of the invention, there is employed an isomeric mixture of 2,4- and 2,6-toluene diisocyanate in which the weight ratio of the 2,4-isomer to the 2,6-isomer is from about 60:40 to about 90:10, and more preferably, from about 65:35 to about 80:20. To form the polyurethane oligomer that is utilized according to the invention, the prepared hydroxyl-terminated prepolymer, as defined above, is then reacted with an anhydride derived from a dicarboxylic acid. The reaction is carried out using methods well known in the art and employing such relative proportions of the reactants so as to achieve an oligomer product having a final free OH content preferably of from about 0 to about 5 percent, and most preferably from about 0 to about 1 percent. Any suitable anhydride which is derived from an aliphatic or aromatic dicarboxylic acid may be used. The anhydride which is employed may be unsubstituted or it may be substituted with any of a variety of substituents, e.g,, alkyl, halo, haloalkyl, cycloaliphatic, aryl, etc. Tllustrative dicarboxylic acid anhydrides include: aliphatic dicarboxylic acid anhydrides such as maleic anhydride, succinic anhydride, glutaric anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, camphoric anhydride, cis-1,2-cyclohexane dicarboxylic anhydride, and the like; and aromatic dicarboxylic acid anhydrides such as phthalic anhydride, homophthalic anhydride, trimellitic anhydride, and the like. Preferred dicarboxylic acid anhydrides for use in the practice of the invention include unsubstituted and substituted maleic anhydrides, succinic anhydrides and glutaric anhydrides. Unsubstituted maleic anhydride, succinic anhydride and glutaric anhydride are the most preferred. By reaction of the hydroxyl-containing prepolymer with the dicarboxylic acid anhydride, a controlled molecular weight polyurethane oligomer with terminal carboxylic acid groups is produced. Preferably, the reaction is carried out in the presence of a reactive copolymerizable solvent. Suitable copolymerizable solvents include vinylidene compounds such as styrene, vinyl toluene, methacrylic esters, acrylic esters, divinyl benzene, and the like, familiar to those skilled in the art. The amount of copolymerizable solvent employed may be varied over a wide range. Generally, however, the copolymerizable solvent is employed in an amount of from about 0 to about 90 parts, and preferably from about 40 to about 70 parts, by weight per 100 parts by weight of the polyurethane oligomer plus copolymerizable solvent. The described polyurethane'oligomer is incorporated into thermosetting polyester resin formulations. These polyester resins include conventional polyesters as well as hybrid polyesters such as vinyl esters. The oligomer modifier additive can be used in any effective proportion. Preferably, the olgomer is added in a proportion ranging from about 6 to about 42 parts by weight per 100 parts by weight of polyester resin plus copolymerizable solvent. Most preferably, the oligomer comprises from about 14 to about 35 parts by weight per 100 parts by weight of the polyester resin plus copolymerizable solvent. The thermosetting polyester resins generally are prepared by reacting dicarboxylic acids or their anhydrides with polyhydric alcohols, using methods and reactants well known to those skilled in the art of polyester technology. Typical reactants include diacids and anhydrides such as phthalic acid, phthalic anhydride, maleic acid, maleic anhydride, and the like, and glycols, such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, butane diol, hexane diol, and the like. The polyurethane oligomer-containing polyester resin system is polymerized and cured in the presence of a heat activated, free radical generating catalyst. The actual curing conditions may vary over wide ranges and are generally dependent on the nature and amount of the particular catalyst employed. Suitable free radical generating catalysts include peroxide or azo type compounds, known to those in the art. Typical peroxide catalysts are illustrated by organo peroxides and hydroperoxides such as benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl perbenzoate, t-butyl hydroperoxide, t-butylbenzene hydroperoxide, cumeme hydroperoxide, t-butyl peroctoate, and the like. Typical azo compounds are azobis-isobutyronitrile, 2-t-butylazo-2-cyano-4-methylpentane, and 4-t-butylazo4-cyano-valeric acid. The preferred catalysts are peroxide catalysts. In particular, preferred peroxide catalysts are t-butyl peroctoate, t-butyl perbenzoate, and mixtures thereof. Any suitable catalytic amount may be employed; however, the catalyst generally is used in an amount from about 0.1 to about 10 parts by weight per 100 parts by weight of polyester, solvent and polyurethane oligomer. The composition of the present invention also contains at least one of a filler or a reinforcement material, and preferably both. Any material known to those in the art as being suitable as a filler may be employed. Generally, a variety of materials, e.g., finely divided solids including CaCO3, clay, alumina, talc, glass microspheres, and the like, may be utilized. Also, any suitable reinforcement material may be used, such as chopped fiberglass, carbon fibers, asbestos fibers, boron nitride whiskers, and the like. The amount of filler generally included in the formulation may vary considerably, but usually ranges from about 50 to about 500, and preferably from about 80 to about 250, parts by weight per 100 parts by weight of the polyester resin, polyurethane oligomer, and copolymerizable solvent. The amount of reinforcing agent added to the formulation may also vary over a wide range; however, a typical formulation will generally contain frdm about 20 to about 300, and preferably from about 75 to about 200, parts by weight per 100 parts by weight of the polyester resin, polyurethane oligomer, and copolymerizable solvent. The composition also may include other standard ingredients, if desired, such as internal mold release agents, e.g., calcium, zinc, magnesium, or sodium stearate. Other low shrink or impact additives also may be included, if desired. Pigments, dyes, stabilizers, thixotropes, wetting agents, viscosity modifiers (e.g., Group II metal oxides and hydroxides, such as magnesium oxide) and various other additives familiar to those skilled in thermosetting polyester technology also may be added. The following examples are provided to further illustrate the invention. All parts are by weight unless otherwise specified. Preparat-ion of Polyurethane Ol-igomeJ EXAMPLE 1 A. A 2-liter reaction flask equipped with stirrer, thermometer and addition funnel was charged with 261 grams (3.0 eq.) of diisocyanate 1. The diisocyanate was heated to 70 C, and 1,486.75 grams (1.5 eq.) of a polyether polyol z were added via the addition funnel. After completion of the addition, the mixture was stirred for 3 hours at 80 C. B. A 2-liter reaction flask equipped with stirrer, thermometer and addition funnel was charged with 164.9 grams (0.15 eq..) of the prepolymer prepared in A.. The prepolymer was heated to 70 C, and 2.32 grams (0.02 eq.) of hydroxyethyl acrylate followed by 100 grams of styrene were added via the addition funnel. The resulting mixture was stirred at 700C for 3 hours. At that time 171.1 grams (0.16775 eq.) of a polyether polyol z followed by 413.1 grams of styrene were added. The reaction was catalyzed by the addition of 1.71 grams of a catalyst , , and the reaction mixture was held at 700C for 3 hours. At that time 3.70 grams (0.03775 eq.) of maleic anhydride were added, and the mixture was stirred for 2 additional hours at 75-800C. The resulting material had a viscosity of 752 cps at 240C. 0 This is a mixture of toluene diisocyanate isomers (80:20 mixtures of 2,4/2,6-isomers). 2 This is a triol having a molecular weight of about 3,000 and prepared by oxypropylating glycerin to a final hydroxyl number of about 56.6. This is a diol having a' molecular weight of about 2,000 and prepared by oxypropylating propylene glycol to a final hydroxyl number of about 55.0. This is dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-1". EXAMPLE 2 A one-liter flask equipped with stirrer, thermometer and addition funnel was charged with a 8.0 grams (0.0079 eq.) of a polyether polyol 1 , 27.65 grams of styrene, 16.38 grams (0.1882 eq.) of diisocyanate0 and 0.09 grams of a catalyst0 The mixture was heated to 700C, and stirred at 700C for 3 hours. The reaction mixture was cooled to room temperature, and 192 grams (0.2012 eq.) of a polyether polyol z followed by 300 grams of styrene were added. An additional 1.0 gram of catalyst z was added, and the mixture was reheated to 70 C. The reaction mixture was stirred at 70eC for one hour. At that point 2.05 grams (0.0209 eq.) of maleic anhydride were added, and the mixture was stirred for an additional 2 hours at 700C. The resulting material had a viscosity of 7,220 cps at 250C. This is a triol having a molecular weight of about 3,000 and prepared by oxypropylating glycerin to a final hydroxyl number of about 56.6. This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers). This is dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-l". This is a polvtetramethylene ether glycol having a molecular weight of about 2,000 and a hydroxyl number of about 58.8. It is a commercial product of The Quaker Oats Company purchased under the designation "Polymeg 2000". EXAMPLE 3 A 2-liter reaction flask equipped with stirrer, thermometer and addition funnel was charged with 388 grams (0.2587 eq.) of a polyester polyol 12.20 grams (0.0115 eq.) of a second polyester polyol 2 and 439.12 grams of styrene. The mixture was heated to 600C, and 19.98 grams (0.2297 eq.) of diisocyanate z followed by 200 grams of styrene were added. The reaction was catalyzed by the addition of 2.12 grams of a catalyst. z , The resulting mixture was stirred at 75-800C for 2 hours, at which point 3.98 grams (0.0406 eq.) of maleic anhydride were added. The resulting mixture was stirred for 2 additional hours at 75-80 C. The resulting material had a viscosity of 970 cps at 260C. 0 This is a diethylene glycol adipate having a molecular weight of about 3,000 and a hydroxyl number of about 37.4. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex S-1011-35". o This is a diethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 52.3. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203". 0 This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers) This is dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-1". EXAMPLES 4 AND 5 Additional polyurethane oligomers were prepared employing the same reactants and conditions as outlined in Example 3. However, different proportions of reactants were used to form prepolymers. These prepolymers were reacted with suitable proportions of maleic anhydride to produce oligomers according to the invention. Table I outlines the oligomer compositions prepared according to Examples 3-5. TABLE I OLIGOMER COMPOSITIONS Polyester Poylols Styrene Diiaocyanate 4 Catalyst 5 Maleic Anhydride Example (eq.) (grams) (eq.) (grams) (eq.) A 1 B 2 C 3 3 0.2587 0.0115 - 639.12 0.2297 2.12 0.0406 4 0.0800 - 0.0769 322.58 0.1255 1.07 0.0313 5 0.0667 0.0945 - 323.31 0.1208 1.07 0.0404 1 This is a diethylene glycol adipate having a molecular weight of about 3,000 and a hydroxyl number of about 37.4. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex S-1011-35". 2 This is a diethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 52.3. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203". 3 This is a diethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 52.3. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203". 4 This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers). 5 This is a dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Formrez UL-1". Polyester Molding EXAMPLES 6-10 Thermoset polyester formulations were prepared containing polyurethane oligomers prepared according to Examples 1-5. The polyester molding formulation used is listed in Table II below. The following procedure was followed in the preparation of the cured composites. a. Into a high shear mixing device were added the polyester resin and polyurethane oligomer. b. The filler, thickener and catalyst were added and mixed until a homogeneous paste was achieved. c. Next chopped fiberglass was added gradually to the paste in a two-roll mill and the mix was worked the minimal length of time to achieve good wet out of the glass without significant breakdown. d. The uncured mix was then placed in a mold between the platens of a compression molding machine and cured under pressure (1,000 psi) for three minutes at 300-3250F. e. Alternatively to (d), the mixture may be added by a hopper device to the screw system of an injection molding device to produce an injection molded part, or the mix may be made up on an SMC machine for later compression or injection molding. The physical properties of panels prepared in this manner are included in Table III below. The physical properties were determined in accordance with standard test procedures: Flexural modulus and flexural strength - ASTM D790; tensile strength - ASTM D3574; and falling dart impact - ASTM D3029. TABLE II POLYESTER MOLDING FORMULATION (BMC) Component 1 Partzs By Weight Polyester Resin z 55 Tertiary Butyl Peroxybenzoate - 0.67 Tertiary Butyl Peroxyoctoate z 0.33 Calcium Carbonate 160 Magnesium Oxide 0.8 1/2 Inch Glass 112 Polyurethane Oligomer 18 Styrene 27 Ol Commercially available from Owens-Corning Fiberglass under the designation "P-340", Commercially available from Lupersol Co. under the designation "PDO", understood to consist of 50% tertiary butyl peroxyoctoate and 50% dioctyl phthalate. COMPARATIVE EXPS LE 1 A thermoset polyester resin was prepared following the procedure of Examples 6-10. The molding formulation employed was as follows: Component 1 Partzs By Weight Polyester Resin z 65 Tertiary Butyl Peroxybenzoate 0.67 Tertiary Butyl Peroxyoctoate z 0.33 Calcium Carbonate 160 Magnesium Oxide 0.8 1/2 Inch Glass 112 Low Shrink Additive 0 35 0 Commercially available from Owens-Corning Fiberglass under the designation "P-340". Commercially available from Lupersol Co. under the designation "PDO", understood to consist of 50% tertiary butyl peroxyoctoate and 50% dioctyl phthalate. 0 Commercially available from Owens-Corning Fiberglass under the designation "P-701". The physical properties of the panel prepared in this manner are included in Table III below. The physical properties were determined in accordance with standard test procedures: Flexural modulus and flexural strength - ASTM D790; tensile strength - ASTM D3574; and falling dart impact ASTM D3029. TABLE III PHYSICAL PROPERTIES OF COMPOSITES Tensile Flexural Flexural Falling Dart Polyurethane Strength Strength Modulus X Impact 1 Surface 2 Example Oligomer (psi) (psi) 106 (psi) (in-lb) (1-5) 6 Example 1 3400 9,900 1.1 53 2.0 7 Example 2 5800 8,400 0.91 45 4.0 8 Example 3 6000 10,900 1.0 56 5.0 9 Example 4 5700 13,700 1.1 48 4.5 10 Example 5 4100 11,400 1.2 53 3.5 CE-1 - 8500 12,700 1.6 24 4.5 1 Failure judged by the appearence of a crack one-eighth inch in length on the side opposite the impact. 2 The surface is rated subjectively from 1-5, 5 having the smoothness of glass, while 1 is a fairly rough and uneven surface. Preparation of Polyurethane Oligomer EXAMPLE 11 A 10-gallon reactor was charged with 26780 grams o; styrene, 876 grams (0.812 eq.) of a polyester polyol 1,16103 grams (10.05 eq.) of a second polyester polyol 0 and 2.353 grams of hydroquinone. The contents of the reactor were mixed thoroughly for 20 minutes and 841.2 grams (9.67 eq.) of diisocyanate 0 followed by 89.9 grams of a catalyst z were added. The resulting mixture was heated to 700C and was mixed at 70-750C for 1 hour, at which point 4.513 grams of hydroquinone and 167.5 grams (1.71 eq.) of maleic anhydride were added. This mixtUre was mixed at 70-750C for 2 hours and then aooled to ambient temperature. A mixture of 2.355 grams of 4-tertiary butyl catechol and 4.51 grams of para-benzoquinone was then added and mixed in thoroughly. 1 This is a di ethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 52. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203". This is a diethylene glycol adipate having a molecular weight of about 3,000 and a hydroxyl number of about 35. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex S-1011-35". 3 This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers). This is a dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-1". EXAMPLE 12 A five-liter reaction flask equipped with stirrer, thermometer and addition funnel was charged with 1358 grams (0.908 eq.) of a polyester polyol 42 grams (0.040 eq.) of a second polyester polyol 2026 grams of styrene, and 0.186 grams of hydroquinone. To this mixture were added 70.07 grams (0.805 eq.) of diisocyanate z , 7.42 grams of a catalyst z , and 200 grams of styrene. The mixture was heated to 750C and was stirred at 750C for 30 minutes. At this point, 0.372 grams of hydroquinone and 14.22 grams (0.142 eq.) of succinic anhydride were added. The resulting mixture was stirred at 750C for 2 hours, cooled to room temperature, and 0.372 grams of para-benzoquinone and 0.186 grams of 4-tertiary butyl catechol were added to the mixture. The oligomer had a viscosity of 945 cps at 260C. 0 This is a diethylene glycol adipate having a molecular weight of about 3,000 and a hydroxyl number of about 37.5. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex S-1011-35". 0 This is a diethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 53.2. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203 n, 3 This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers). 4 This is dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-l11. EXAMPLE 13 A one-liter reaction flask equipped with stirrer, thermometer and addition funnel was charged with 194 grams (0.130 eq.) of a polyester polyol 6 grams (0.006 eq.) of a second polyester polyol 218 grams of styrene, and 0.027 grams of hydroquinone. To this mixture were added 10.01 grams C0.115 eq.) of diisocyanate , , 70 grams of styrene, and 1.06 grams of a catalyst z , The mixture was heated to 750C and was stirred at 750C for 30 minutes. At this point 0.053 grams of hydroquinone and 2.27 grams (0.020 eq.) of citraconic anhydride were added. The resulting mixture was stirred at 750C for 2 hours and cooled to room temperature. To the cooled mixture were added 0.053 grams of para-benzoquinone and 0.027 grams of 4-tertiary butyl catechol. The resultant mixture had a viscosity of 960 cps at 280C. 0 This is a diethylene glycol adipate having a molecular weight of about 3,000 and a hydroxyl number of about 37.5. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex S-1011-35". 0 This is a diethylene glycol adipate derived from glycerin and diethylene glycol and having a molecular weight of about 3,000 and a hydroxyl number of about 53.2. It is a commercial product of Hooker Chemical Corporation purchased under the designation "Rucoflex F-203". O3 This is a mixture of toluene diisocyanate isomers (80:20 mixture of 2,4/2,6-isomers). 0 This is dibutyl di (lauryl mercapto) tin and is a commercial product of Witco Chemical Corporation purchased under the designation "Fomrez UL-1". EXAMPLES 14-16 Additional polyurethane oligomers were prepared employing the same reactants and conditions as outlined in Example 13, except that different dicarboxylic acid anhydrides were used as follows: Amount of Viscosity of Dicarboxylic Oligomer Example Dicarboxylic Acid Anhydride Product No. Acid Anhydride (eq.) (cps) 14 Glutaric 0.020 820 Anhydride (at 260C) 15 Tetrahydro- 0.020 970 phthalic (at 240C) anhydr ide 16 Phthalic 0.020 870 Anhydride (at 250C) Polyester Molding EXAMPLES 17-22 Thermoset polyester formulations were prepared containing polyurethane oligomers prepared according to Examples 11-16. The polyester molding formulation used is listed in Table IV below. The following procedure was followed in the preparation of the cured composites. a. Into a high shear mixing device were added the polyester resin and polyurethane oligomer. b. The filler, thidkener and catalyst were added and mixed until a homogeneous paste was achieved. c. Next chopped fiberglass was added gradually to the paste and mixed in carefully by hand. The paste-fiberglass mixture was placed between two polyethylene sheets and was rolled flat with a rolling pin. d. The uncured mix was stored between the polyethylene sheets for one day to allow maturation to take place. e. The uncured mix was then placed in a mold between the platens of a compression molding machine and cured under pressure (1,000 psi) for three minutes at 300-3250F. f. Alternatively to (e), the mixture may be added by a hopper device to the screw system of an injection molding device to produce an injection molded part, or the mix may be made up on an SMC machine for later compression or injection molding. The physical properties of panels prepared in this manner are included in Table IV below. The physical properties were determined in accordance with standard test procedures: Flexural modulus and felxural strength - ASTM D790; tensile strength - ASTM D3574; and falling dart impact - ASTM D3029. TABLE IV POLYESTER MOLDING FORMULATION Component Parts By Weight Polyester Resin 0 65 Tertiary Butyl Peroxybenzoate 0.65 Tertiary Butyl Peroxyoctoate 2 0.35 Calcium Carbonate 160 Magnesium Oxide 0.8 d Inch Glass 112 Polyurethane Oligomer 14 Styrene 21 O Commercially available from Owens-Corning Fiberglass under the designation "P-340". Commercially available from Lupersol Co. under the designation "PDO", understood to consist of 50% tertiary butyl peroxyoctoate and 50% dioctyl phthalate. COMPARATIVE EXAMPLE 2 A thermoset polyester resin was prepared following the procedure of Examples 17-22. The molding formulation employed was as follows: Component Parts by Weight Polyester Resin0 z 65 Tertiary Butyl Peroxybenzoate 0.67 Tertiary Butyl Peroxyoctoate 2 0.33 Calcium Carbonate 160 Magnesium Oxide 0.8 h Inch Glass 112 Low Shrink Additive z 35 0 Commercially available from Owens-Corning Fiberglass under. the designation "P-340". 0 Commercially available from Lupersol Co. under the designation "PDO", understood to consist of 50% tertiary butyl peroxyoctoate and 50% dioctyl phthalate. 0 Commercially available from Owens-Corning Fiberglass under the designation "P-701". The physical properties of the panel prepared in this manner are included in Table V below. The physical properties were determined in accordance with standard test procedures: Flexural modulus and flexural strength - ASTM D790; tensile strength - ASTM D3574; and falling dart impact - ASTM D3029. TABLE III PHYSICAL PROPERTIES OF COMPOSITES Dimensional Change 3 Tensile Flexural Flexural Falling Dart (10-3 in/in) Polyurethane Strength Strength Modulus Impact 1 Surface 2 Width- Length Example Oligomer (psi) (psi) X 10 (psi) (in-lb) (1-5) wise wise 17 11 5820 14,500 1.55 8.4 3 0.25 0.45 18 12 6370 14,200 1.66 5.8 2.5 0.20 0.45 19 13 3880 7,600 1.23 7.0 2.5 0.20 0.35 20 14 6320 11,600 1.35 8.2 2.5 0.25 0.35 21 15 6440 15,900 1.64 6.8 3.0 0.30 0.40 22 16 6290 13,300 1.43 9.0 3.0 0.25 0.35 CE-2 - 8120 16,200 1.90 7.0 2.0 -- -1 Failure determined by the first appearance of a crack on the side opposite the impact. 2 The surface is rated subjectively from 1-5,5 having the smoothness of glass, while 1 is a fairly rough and uneven surface. 3 Dimensional change is determied for each example by first measuring an average length dimension and an average width dimension for the cured composite. An average length dimension and an average width dimension are also obtained for the cured panel of Comparative Example 2. The differences between the average length and average width of each example, respectively, and Comparative Example 2 are reported in Table V as dimensional change in units of 10-3 in. per in. of panel. A positive value demonstrates less shrinkage in the example panel than in the panel of Comparative Example 2.

Claims: CLAIMS 1. A thermosetting polyester resin composition comprising a polyester resin, a heat activated free radical generating catalyst, at least one of a reinforcing agent or a filler, and a polyurethane oligomer, said polyurethane oligomer having a final free OH content of from about 0 to about 5 percent and being prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of an organic polyisocycanate with a polyol having an average molecular weight of about 300 to about 10,000, in an equivalent ratio of NCO to OH in the range from about 0.3/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride. 2. The composition of Claim 1, including a copolymerizable solvent and from about 6 to about 42 parts by wiubt of said oligomer per 100 parts by weight of polyester resin plus copolymerizable solvent. 3. A composition according to Claim 2, which includes from about 14 to about 35 parts by weight of said polyurethane oligomer per 100 parts by weight of polyester resin plus copolymerizable solvent, and wherein said polyurethane oligomer has a final free OH content from about 0 to about 1 percent and is prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of toluene diisocyanate with a polyester polyol having an average molecular weight of about 500 to about 6,500 in an equivalent ratio of NCO to OHin the range from about 0.60/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride selected from unsubstit uted maleic anhydride, succinic anhydride, and glutaric anhydride. 4. A process for preparing a thermoset polyester resin composition comprising mixing a polyester resin, a heat activated free radical generating catalyst, at least one of a reinforcing agent or a filler and a polyurethane oligomer, and then heating said mixture at a temperature adequate to activate said catalyst and cure said mixture, said polyurethane oligomer having a final free OH content from about 0 to about 5 percent and being prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of an organic polyisocyanate with a polyol having an average molecular weight of about 300 to about 10,000 in an equivalent ratio of NCO to OH in the range from about 0.3/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride. 5. A process according to Claim 4, wherein there is included in said mixture from about 14 to about 35 parts by weight of said oligomer per 100 parts by weight of polyester resin plus styrene copolymerizable solvent and wherein said oligomer has a final free OH content from about 0 to about 1 percent and is prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of toluene diisocyanate with a polyester polyol having an average molecular weight of about 500 to about 6,500 in an equivalent ratio of NCO to OH in the range from about 0.60/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride selected from unsubstituted maleic anhydride, succinic anhydride, and glutaric anhydride. 6. A thermoset polyester article prepared by a process according to claim 4 or 5. 7. A polyurethane oligomer having a final free OH content from about 0 to about 5 percent and being prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of an organic polyisocyanate with a polyol having an average molecular weight of about 300 to about 10,000, in an equivalent ratio of NCO to OH in the range from about 0.3/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride. 8. A composition or oligomer according to Claim 1 or 7, wherein said reaction- is carried out in the presence of a copolymerizable solvent. 9. A composition or oligomer according to Claim 8, wherein said copolymerizable solvent is styrene. 10. A composition or oligomer according to Claim 1 or 7, wherein said prepolymer is the reaction product of a polyisocyanate and a polyol in an equivalent ratio of NCO to OH in the range from about 0.60/1 to about 0.99/1. 11. A composition or oligomer according to Claim 1 or 7, wherein the final free OH content of said oligomer is from about 0 to about 1 percent. 12. A composition or oligomer according to Claim 1 or 7, wherein said dicarboxylic acid anhydridje is selected from unsubstituted maleic anhydride, succinic anhydride, and glutaric anhydride. 13. A composition or oligomer according to Claim 1 or 7, wherein said prepolymer is prepared from a polyester polyol. 14. A composition or oligomer according to Claim 13, wherein said polyester polyol has an average molecular weight in the range from about 500 to about 6,500. 15. A composition or oligomer according to Claim 1 or 7, wherein said prepolymer is prepared by employing toluene diisocyanate as said organic polyisocyanate. 16. A composition or oligomer according to Claim 1 or 7, wherein said polyurethane oligomer has a final free OH content from about 0 to about 1 percent and is prepared by reacting (a) a hydroxyl-terminated prepolymer which is the reaction product of toluene diisocyanate with a polyester polyol having an average molecular weight of about 500 to about 6,500 in an equivalent ratio of NCO to OH in the range from about 0.60/1 to about 0.99/1 with (b) a dicarboxylic acid anhydride selected from unsubstituted maleic anhydride, succinic anhydride, and glutaric anhydride.

Inventors: LICKEI, DONALD LEE, O'CONNOR, JAMES MICHAEL, ROSIN, MICHAEL LEE
Applicants: OLIN CORPORATION
Application year: 1982
Main classification: C08L67
IPC codes: C08L67, C08G18