GB2073214A - Dicyclopentadiene Polyester Resins - Google Patents

Abstract

The invention disclosed is for a method of preparing unsaturated polyester resins containing high amounts of dicyclopentadiene by reacting dicyclopentadiene with an unsaturated dicarboxylic acid and then reacting the product with a polyol.

Description

SPECIFICATION Dicyclopentadiene Polyester Resins This invention relates to the preparation of unsaturated polyester resins containing high amounts of dicyclopentadiene.

Cyclic structures in the alkyd portion of a polyester normally increase compatibility with styrene and provide rigidity and toughness in the cured resin. Low-cost phthalic anhydride is the most widely used cyclic polyester intermediate. Substitution of other cyclic intermediates for phthalic anhydride in a polyester formulation, however, often results in an improvement of one or more resin properties; for example, isophthalic acid polyesters have better resilience and corrosion resistance, and polyesters derived from certain bisphenol A derivatives have very superior corrosion resistance.

Dicyclopentadiene is a well-known, readily available raw material available from the petoleum industry.

Although dicyclopentadiene exists both as an endo and exo isomer, the commercial product is a liquid consisting principally of the endo form and contains a minimum of 90 weight percent available cyclopentadiene. Since dicyclopentadiene is very susceptible to peroxide formation upon contact with air, the commercial product is usually inhibited with p-tertiary butyl catechol.

Dicyclopentadiene is used principally as a source of cyclopentadiene, a highly reactive monomer, and being a conjugated diene, it readily undergoes the Diels-Alder reaction for form cyclohexene derivatives having a bridged ring or endomethylene group.

The following methods for incorporating dicyclopentadiene into a polyester are known. The anhydride method has been known wherein the preformed Diels-Alder adduct of cyclopentadiene and maleic anhydride is reacted with further amounts of maleic anhydride and a glycol in a polyesterificatior reaction at 2000C. Another method involves reacting a mixture of maleic anhydride, dicyclopentadiene and a glycol at 1 600C-1 800C followed by polyesterifying at 2000C.

Yet another known method consists of pre-reacting maleic anhydride and glycol at 1 600C to obtain an ester-acid prior to reaction with dicyclopentadiene at 1700--1750C and polyesterification at 2000 C. A further known method involves polyesterification of maleic anhydride and a glycol at 2000C followed by subsequent reaction with dicyclopentadiene at 1600--1700C.

It has also been known to prepare thermosettine polyester compositions by mixing together a vinyl monomer such as, for example, styrene and an unsaturated polyester resin such as the prior art resins discussed above or those obtained by condensing maleic anhydride with a dihydric alcohol, such as ethylene glycol. The constituents of such compositions upon gentle heating and particularly in the presence of a peroxide or azo catalyst readily copolymerize or crosslink to infusible products that are substantially insoluble in many common organic solvents.

In the known prior art methods, there is a limitation on the amount of dicyclopentadiene that may be incorporated into the polyester. It has now been found that by practice of the present invention it is possible to react much higher amounts of dicyclopentadiene into the polyester and yet prepare a commercially acceptable product.

In the method of the present invention, a polycarboxylic acid is reacted initially with dicyclopentadiene. The reaction product is then reacted with a polyhydric alcohol to form an unsaturated polyester resin. The unsaturated polyester resin, when combined with a monomeric copolymerizable component, may then be thermoset by methods well known to the polyester resin art.

According, therefore, to the present invention, there is provided a method of preparing an unsaturated polyester, comprising reacting a polycarboxylic acid component containing at least 25 mole percent maleic acid with 50 to 200 moles of dicyclopentadiene per 100 moles of said polycarboxylic acid at a temperature of 900C to 1 500C to provide a reaction product comprising at least 25 mole percent of the half maleic ester of dicyclopentyl alcohol, and reacting said reaction product with 25 to 100 moles of a polyol or mixture of polylols per 100 moles of said polycarboxylic acid at a temperature of at least 1 800C until the acid number of the resultant unsaturated polyester is less than 55.

The reaction of maleic an hydride and water proceeds with stoichiometric amounts of water.

However, if is often desirable to include an excess amount of water.

The unsaturated polyester resin preferably has a Gardner-Holdt Viscosity of at least H at 30% xylene. Polyesters of an average molecular weight of less than 1000 will normally be of a visocosity too low to impart to copolymer compositions the consistency required for satisfactory product formation. Polyesters of average molecular weight higher than about 2000, although capable of being copolymerized with vinyl monomers, are generally not desirable for use in the practice of the present invention, since such polyesters are difficult to manufacture and involve uneconomical reaction processing times of twenty hours and more at reaction temperature of about 2000C.

Curable liquid compositions may be produced containing 40 to 80 parts by weight of the unsaturated polyester resin component and 20 to 60 parts by weight, preferably 25 to 50 parts by weight, of a monomeric copolymerizable component.

The unsaturated polyester resin may include, in addition to maleic acid, other alpha, betaunsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, mesa conic acid and aconitic acid. A portion of the alpha, beta-unsaturated dicarboxylic acids may also be replaced with saturated dicarboxylic acids such O-phthalic acid and isophthalic acids, tetrachlorophthalic acid, endomethylene-tetrahydrophthalic acid, adipic acid, chiorendic acid and sebacic acid, as well as dimerized linseed oil and soya oil, fatty acids or their anhydrides.

Dicyclopentadiene (DCPD) is usually incorporated as the commercial product described above.

One may alternatively use the commercially available "Cyclodiene Dimer Concentrate" sold by Exxon Chemicals and containing approximately 59% dicyclopentadiene, approximately 25% methyl dicyclopentadiene dimer and the remainder hydrocarbon materials. This mixture of DCPD and methyl DCPD dimer is less reactive than DCPD alone and cannot be used at equal concentration levels.

The polyhydric alcohols, preferably dihydric alcohols, in the unsaturated polyester are, for example, ethylene glycol; propanediol; 1,4-, 1,3-, or 2,3-butanediol; diethylene glycol; dipropylene glycol and the higher homologues; neopentyiglyccl; 2,2,4-trirnethylpentanediol-1 3; oxalkylated bisphenols; hydrogenated bisphenol and cyclohexane dimethanol. Trihydric and polyhydric alcohols such as glycerine, trimethylolethane, trimethyiolpropane, as well as pentaerythritol, may also be used conjointly with the preferred glycols if desired.

Further variations in the properties of the unsaturated polyester resins may be achieved by adding monofunctional compounds during the polycondensation, for example, by adding fatty acids having about 8 to about 22 carbon atoms, benzoic acid, resin acids, partially hydrogenated resin acid, such as abietic acid and/or dihydroabietic or tetrahydroabietic acids, monohydric n-alcohols having about 12 carbon atoms, benzyl alcohols and a resin alcohol such as abietyl alcohol.

The monomeric copolymerizable component may be styrene, vinyl toluene, divinyl benzene, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethyl hexyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate and its higher homologues, such as diethylene glycol dimethacrylate, trimethylolpropane trimethylacrylate, diallyl phthalate, diallyl maleate, diallyl fumarate, triallyl cyanurate, vinyl acetate and vinyl propionate. Styrene is preferred for economic reasons. Other available monomeric materials may be used if desired. The monomeric copolymerizable components may be used either separately or in various combinations as desired.

The amounts of vinyl monomers used for copolymerization are determined to some extent by the characteristics desired in the copolymer. In general, the higher the vinyl content the more brittle the copolymer, although this will vary in degree with the monomer used. Thus, at the same concentration, an ethyl acrylate copolymer is considerably more flexible than a styrene copolymer Polycondensation of the unsaturated polyester resin components may be carried out using conventional techniques until the mixture has an acid number of about 50 or less, preferably 2 to 40.

The esterification reaction should be sufficiently prolonged to ensure the production of a polyester of desired molecular weight and desired viscosity. The extent of esterification is conveniently measured by acid number and viscosity determinations.

In order to ensure adequate storage stability for the curable liquid compositions of the invention, effective amounts of inhibitors may be added, such as hydroquinone, monotertiarybutyl-hydroquinone, benzoquinone, 1 ,4-naphthoquinone, 2,5-diphenyl-p-benzoquinone and p-tert butyl pyrocatechol and the like.

The polymerizable composition of the invention may contain, as further optional ingredients, fillers, catalyst, inhibitor and/or antioxidant, lubricant, thici < ening agent, dyestuffs and/or inorganic pigments and fiberglass.

Fibrous materials usefully added to the resinous system include materials typically used as reinforcing agents such as glass fabrics, chopped glass strands, chopped or continuous strand glass fiber mat, asbestos, cotton. synthetic organic fibers, metal fibers and the like. The glass containing reinforcing agents are preferred.

Various other additives may be included in the present resinous system such as colorants, pigments, moid release agents, lubricants, polymerization initiators and the like, as desired.

Curing of the resinous composition may be effected in a mold maintained at a temperature from about 21 2 OF to about 35Q F, with pressures in the range from about 100 to about 1500 psi.

Curing is effected within about 30 seconds up to about 5 minutes, depending upon the presence of optional additives, the thickness of the mass being n:o'ded and related variables well known to those skilied in the art.

Curing at ambient temperature msy be effected using activator systems employed in conventional polyester resins for ambient temperature curing. These include systems such as benzoyl peroxide-dimethyl aniline, methyl ethyl ketone peroxide-cobalt octoate and the like.

The present invention is further illustrated by the fjllowing examples wherein all parts are given by weight (in grams) unless otherwise indicated. Regular glassware equipment was used plus a water trap and a water cooled condenser on top of a short column. AII reactions were conducted under nitrogen atmosphere.

Example 1 Parts by Ingredient weight (Grams) Maleic Anhydride 1441 Water 290 Dicyclopentadiene 2524 Pentaerythritol 200 Propylene Glycol 335 MTBHQ (monotertiarybutyl-hydroquinone) 0.22 Maleic anhydride and water were added to a glass flask and heated to about 55 C. The heat was turned off and the reaction allowed to exotherm to about 1 220C. After the temperature started to drop, dicyclopentadiene was added and the reaction mixture heated slowly to 1 200C. The heat was turned off, and at 1 250C cooling was started. The reaction was held at 130-1 350C for 30 minutes. The reaction was heated slowly to 1 450C and held there until the acid number was less than 1 65 (about 1 1/2 hours).Propylene glycol, pentaerythritol and the MTBHQ were added in that order. The pot temperature was raised to 210C over 2 to 3 hours, removing the water as it was formed and returning the dicyclopentadiene to the pot. After 2100C was reached, everything that was distilled was removed. After one hour at 21 00C a sparge tube was added and nitrogen flow increased. After one hour sparging, the column was removed. After 8 hours at 21 00C the Gardner-Holdt viscosity was E-F (60 percent polyester in xylene) and the acid number of the solution was 7. The total weight of distillate was 293 grams, of which 240 grams was water and 53 grams was an organic liquid heavier than water. After cooling to 180--1900C, 0.22 gram of MTBHQ was added.The resin was added to 2400 grams of styrene containing an additional 0.22 gram of MTBHQ. The resin was adjusted to a Gardner-Holdt viscosity of G-H with styrene and 0.25 percent of diethylene glycol and 1.0 percent of pyrogenic silica were added and mixed. Two percent styrene was added to give a 20 RPM Brookfield viscosity of 820 centipoises and 2 RPM Brookfield viscosity of 3000 centipoises for a 3.7 thixotropic index. The SPI gel time gave a 3690F peak.

Gel Time at 770F in presence of 0.1% Dimethyl Aniline, 0.2% of 12% Cobalt and 0.5% Lupersol DDM Catalyst 7 min.

Interval (time from Gel to peak exotherm) 18 min.

Peak, OF 261 The prepared product was found useful as a laminating resin.

Example 2 The procedure of Example 1 was repeated with the following: Parts by Ingredient Weight (Grams) Maleic Anhydride 999 Phthalic Anhydride 81 3 Water 310 Dicyclopentadiene 2071 Propylene Glycol 382 Pentaerythritol 235 MTBHQ 0.22 The reaction was run the same as Example 1. After dicyclopentadiene was added less cooling was required to hold the reaction at 130-1 450C than in Example 1. The reaction was held at 1 450C until an acid number of less than 210 was reached. Thereafter the glycol, pentaerythritol and MTBHQ were added and the mixture was cooked at 21 00C to a Gardner-Holdt viscosity of G-H (60 percent polyester in xylene) and a solution acid number of 1 7. There were 320 ml of distillate with 40 ml of the heavier organic layer.After cooling to 1 900C, 0.22 gram of MTBHQ was added to the resin. The resin was cut into 2400 grams of styrene containing an additional 0.22 gram MTBHQ. After adjusting to a Gardner-Holdt viscosity of G-H with styrene, 0.25 percent of diethylene glycol (DEG) and 1.0 percent pyrogenic silica were added based on the weight of thinned resin. The Brookfield viscosity at 20 RPM was 730 centipoises and at 2 RPM was 2500 centiposes for a thixotropic index. The SPI gel time gave a 3340speak.

Gel Time at 770F in presence of 0.1% Dimethyl Aniline, 0.2% of 12% Cobalt and 0.5% Lupersol DDM Catalyst 5 min.

Interval (time from Gel to peak exotherm) 16 min.

Peak, bF. 251 The prepared product was found useful as a laminating resin.

Example 3 The procedure of Example 1 was repeated, except using the following: Parts by Ingredient Weight (Grams) Maleic Anhydride 1621 Water 325 Dicyclopentadiene 21 83 Propylene Glycol 628 Pentaerythritol 68 MTBHO 0.22 The reaction was run the same as in Example 1. However, after dicyclopentadiene was added, cooling was started at once to control the exotherm at 1 30--1 35 OC. The reaction was held at 1 450C until an acid number of less than 225 was reached (about 1-1/2 hours). After addition of the polyols and MTBHQ the mixture was cooked at 21 00C to a Gardner-Holdt l-J viscosity (60 percent polyester in xylene) and a solution acid number of 12.At 1 900C, 0.22 gram of MTBHQ was added and the resin was then blended into 1 900 grams of styrene containing an additional 0.22 gram MTBHQ. The product, containing 31.3 percent styrene, had a Gardner-Holdt viscosity of Y 1/2. The SPI gel time had a 4000F exotherm. The prepared product was found useful as a molding resin.

Example 4 The product of Example 1 was used to prepare a laminate according to the following formulation: Parts by Ingredient Weight (Grams) Product Example 1 384.00 Styrene 16.00 12% Cobalt Octoate 0.40 Dimethyl Aniline 0.20 MTBHQ 0.04 Methyl Ethyl Ketone Peroxide (60%) 4.00 The laminate was prepared using 3 ply of 1-1/2 oz. fiberglass mat. it was cured 3 days at room temperature and one hour at 212 OF. Average thickness of the laminate was .091 inches.

Physical properties at 720F are as foliows: Tensile strength 16,400 psi Tensile modulus 1.1 x 106 psi Flexural strength 31,000 psi Flexural modulus 1.1 xl 06 psi Example 5 Parts by Ingredient Weight (Grams) Maleic Anhydride 1282 Water 706 Dicyclopentadiene 2246 Propylene Glycol 258 Pentaerythritol 214 MTBHQ 0.22 In this procedure, extra water in the formulation reduces the reflux temperature and no exotherm is obtained. However, fast stirring was required to reduce foaming. Maleic anhydride and water were heated to 1 000C and thereafter dicyclopentadiene added. The reaction mixture was heated to 111 OC and refluxing started.The water was removed until a pot temperature of 1 450C was reached and the dicyclopentadiene returned to the pot. After the temperature reached 1 45 OC the reaction procedure was completed in the same manner as described in Example 1.

Example 6 A series of experiments were prepared by the procedure following except varying the types and parts by weight of reactants (in grams) as indicated in Table 1. Maleic anhydride (MA) and water were weighed into a 5 liter flask and warmed until the maleic anhydride melted and reacted with the water.

The heat was turned off and the reaction allowed to exotherm. When the temperature started to drop dicyclopentadiene (DCPD) was added and the reaction mixture heated at 1 40--1 45 OC under total reflux for two hours. The acid number was 1 75 or less. The pentaerythritol (Penta) and/or propylene glycol (PG) or diethylene glycol (DEG) or sorbitol, as noted, were added and the temperature raised slowly to 21 00C with the water being removed as it formed. The reaction was run to a Gardner-Holdt viscosity of G-H (60 percent polyester in methyl cellosolve) and solution acid number of 1015.

MTBHQ inhibitor (0.20 grams) was added at 1 800C and the resin blended into styrene containing an additional 0.20 gram MTBHQ inhibitor. The amount of styrene added was that needed to provide a Gardner-Holdt viscosity of G-H. Pyrogenic silica (1.0 percent) and diethylene glycol (0.2 percent) were added and mixed for 5 minutes. This gave a Brookfield viscosity at 20 RPM of 750 to 900 centipoises and a thixotropic index of 3 to 4. In all cases, the amount of the percentage additives is based on the combined weight of styrene and the unsaturated polyester resin. In Table I, the control, designated as Run 6-6, was prepared from MA and phthaiic anhydride (PA) using conventional techniques well known to the prior art.

Table I DCPD Laminating Resins Parts Parts Parts Parts Parts Styrene Heat Distortion by Wt by Wt by Wt by Wt by Wt %Total Exotherm Exotherm Temperature of Run MA Water DCPD PG Penta &commat; G-H Vis. R.T. Gel(1) SPI Gel 1/8" Casting 6-1 1229 248 2060 285 170 40 301 F 399 F 6-2 1203 243 2107 280 167 41.5 288 F 380 F 228 F 6-3 1176 238 2060 330 196 40.4 273 F 365 F 198 F 6-4 1200 242 2101 279 178 45 286 F 367 F 230 F Sorbitol 6-5 1203 243 2107 280 167 41 288 F - 6-6 557 MA - - 1482 - 42 270 F 365 F 172 F (Control) 1961 PA (1) 0.2% 12% Cobalt 0.05% DMA 0.5% DDM at 77 F.

Table II Physical Properties 1/8 inch laminates were prepared from 1 layer of glass cloth,2 2 layers 1-1/2 oz. glass mat and top layer of glass cloth. The laminates were cured overnight at room temperature and one hour at 2480F.

Flexural Strength Flexural Modulus Tensile Strength Run PSI PSI PSI 6-6 28,000 1.26x106 15,000 (Control) 6-5 26,000 1.2x106 12,600 6-2 28,000 1.2x106 6-3 29,000 1.4x106 In the following examples, the reactants are stated in terms of mole percent. Examples 7, 8 and 9 demonstrate the use of increasing ratios of DCPD to carboxylic acid; Examples 10 and 11 employ temperature variation in the first and second steps, respectively; Examples 12 and 1 3 illustrate the use of phthalic acid and adipic acid, respectively.

Example 7 Mole % Wgt % Grams Step 1 100 MA 26.65 1199 105 Water 5.14 231 160 DCPD 57.44 2584 Step II 20 Ethylene 3.37 1 52 glycol EG 20 Penta 7.40 333 Hydroquinone .01 .5 Step I The 5-liter flask was equipped with a stirrer, nitrogen inlet tube, thermometer and distillation column. The DCPD and water were added to the flask followed by molten MA. The reaction was allowed to exotherm to about 1 250C and cooling was applied. The reaction was held at 130--1356C for 4 hours until an acid number of 1 53 was reached.

Step II The ethylene glycol, pentaerythritol (Penta) and hydroquinone were added to the flask and slowly heated to 21 00C removing water and some organic material from the reaction. After abou 2 hours at 21 00C, a sparge tube was added and the nitrogen rate increased. After 18 to 20 hours at 2100C, the Gardner-Holdt Viscosity was G at 40% xylene and the acid number was 5.

Monotertiarybutylhydroquinone (0.38 grams) was added to the resin and blended into 2000 grams of styrene containing 0.38 grams MTBHQ. The product contained 36.2% styrene and had a viscosity at 770F of 460 cps.

Example 8 Mole % Wgt. % Grams Step I 100 MA 24.79 1116 105 Water 4.78 215 180 DCPD 60.11 2705 Step II 30 Penta 10.32 464 Hydroquinone 0.13 .6 Step I The molten MA was added to the DCPD and water using equipment the same as Example 7 and allowed to slowly exotherm to 1 200C. The reaction was held at 1 200C for 8 hours until an acid number of 120 was reached.

Step II The pentaerythritol (Penta) and hydroquinone were added and heated slowly to 21 00C. Water and some organic materials were removed. After 2 hours at 21 00C, a sparge tube was added and the nitrogen rate increased. After 4 hours at 21 O0C, the Gardner-Holdt Viscosity was F at 40% xylene and an acid number of 53. Hydroquinone (0.25 grams) was added to the resin and blended into 2000 grams of styrene containing. 0.25 grams of hydroquinone.

Example 9 Mole % Wgt.% Grams Step I 100 MA 21.78 653 200 DCPD 58.67 1760 300 Water 12.00 360 Step II 25 Penta 7.56 227 Hydroquinone .005 0.15 Step I A 5-liter flask containing a stirrer, gas inlet tube, thermometer, addition funnel and column was added. The MA and DCPD were added to the flask and warmed to 80-1 000C. The water was slowly added and the temperature went up to 1 250C and slowly fell to 103-1 070C as water was added.

The reaction was held under reflux at 103-1 070C for 2-1/2 hours. Then water was slowly removed returning the DCPD to the pot until a pot temperature of 1 400C was reached. The reaction was held at 1 400C for 1 hour and at this time the acid number was 107.

Step II The pentaerythritol (Penta) and hydroquinone were added and slowly heated to 21 50C removing water and some organic material.

After 2 hours at 21 50C, a sparge tube was added and the nitrogen rate increased. After about 8 hours at 21 50C, the Gardner-Holdt Viscosity was F 1/1 at 40% xylene and the acid number was 10.

Hydroquinone (0.06 grams) was added to the resin and blended into 1000 grams of styrene containing 0.06 grams of hydroquinone.

A laminate was prepared from 225 grams of resin (1100 cps. at 77 F,31.3% styrene), 25 grams of styrene, 2.5 grams of dimethylaniline and 5 grams of benzoyl peroxide, using 3 plies of 1-1/2 oz.

glass. After curing for 3 days at room temperature, it had a Barcol hardness of 35-43. After curing 4 hours at 100 C, the Barcol was 40-43. The glass-free resin along the edge of the laminate was hard and brittle.

Example 10 Mole % Wgt. % Grams Step I 100 MA 31.94 1437 116 DCPD 50.00 2250 101 Water 5.94 267 Step II 60 EG 12.12 545 Hydroquinone .025 1.1 Step I The water and MA were added to the flask (same equipment as Example 7) and warmed to meit the MA. The reaction exotherm was cooled to 85 to 95bC and the DCPD added slowly with cooling, keeping the temperature below 950C. The reaction was held at 900C for 6 hours until an acid number of 183 was reached.

Step II The EG and hydroquinone were added and heated slowly to 21 50C removing water and some organic material. After 2 hours at 21 50C, a sparge tube was added and the nitrogen rate increased.

After 14 hours at 21 50C, the viscosity was F1/2 at 40% xylene and the acid number was 10.

Hydroquinone (0.25 grams) was added to the resin and blended into 2000 grams of styrene containing 0.25 grams of hydroquinone.

Example 11 Mole % Wgt. % Grams Step I 50 MA 16.36 736 50 PA 24.71 1112 105 Water 6.31 284 80 DCPD 35.26 1587 Step II 40 EG 8.28 373 20 Penta 9.08 408 Hydroquinone 0.01 0.05 Step I The DCPD, water, MA and PA were added to the flask (same equipment as Example 7) and slowly warmed to 130-1 400C. The flask was cooled slightly at 125-1 350C to control a slight exotherm.

The reaction was held at 130--1406C for 8 hours until an acid nurnber of 240 was obtained.

Step II The EG, pentaerythritol (Penta), hydroquinone and about 5% of toluene were added. A water trap was added on top of the column. The reaction was slowly heated to 1 80C using a toluene azeotrope to remove the water. Toluene was added from time to time to keep the reaction refluxing at 1800 C.

After 12 hours the viscosity was F in 40% xylene and the acid number was 30.

MTBHZ (0.5 grams) was added to the resin and blended into 2000 grams of styrene containing 0.5 grams of MTBHQ.

Example 12 Mole% Wgt. % Grams Step I 30 MA 8.74 262 70 PA 30.80 924 70 DCPD 27.47 824 300 Water 16.05 482 Step II 70 EG 12.90 387 10 Penta 4.04 121 Hydroquinone .005 0.15 Step I The MA, PA and DCPD were placed into a 4-liter resin flask containing a stirrer, gas inlet tube, addition funnel, thermometer and water trap. The material was heated to 90-1 000C and the water slowly added and held under reflux for one hour. Then the water was slowly removed using the water trap and returning the DCPD to the flask until the pot temperature was 1 350C. The reaction was held at 1 350C for 5 hours. The phthalic acid was not completely soluble in the reaction and formed a thick slurry.

Step II The EG, pentaerythritol (Penta) and hydroquinone were added to the flask and slowly heated to 21 50C removing the water and some organic material. After two hours, a sparge tube was added and the nitrogen rate increased. After 4 hours, the Gardner-Holdt Viscosity was F 1/2 at 40% xylene.and the acid number was 20.

Hydroquinone (0.15 grams) was added and the resin blended into 1000 grams of styrene containing 0.15 grams of hydroquinone.

Example 13 Mole% Wgt.% Grams Step I 75 AA 39.11 1564 25 MA 8.75 350 50 Water 3.21 128 70 DCPD 33.00 1320 Step II 50 EG 11.07 443 10 Penta 4.86 194 Hydroquinone 0.013 0.5 Step I All the reactants were added to the flask (same equipment as Example 7) and heated slowly to 1 300C and held there for 8 hours until an acid number of 374.

Step II The EG, pentaerythritol (Penta) and hydroquinone were added and cooked at 21 5 C for 8 hours until a Gardner-Holdt Viscosity of H at 30% xylene and an acid number of 41. Hydroquinone (0.25 grams) was added to the resin and blended into 1 600 grams of styrene containing 0.25 grams of hydroquinone.

All the products in the above examples formed hard of tough material when co-polymerized with styrene.

Claims (8)

Claims

1. A method of preparing an unsaturated polyester, comprising reacting a polycarboxylic acid component containing at least 25 mole percent maleic acid with 50 to 200 moles of dicyclopentadiene per 100 moles of said polycarboxylic acid at a temperature of 900C to 1 500C to provide a reaction product comprising at least 25 moles percent of the half maleic ester of dicyclopentyl alcohol, and reacting said reaction product with 25 to 100 moles of a polyol or mixture of polyols per 100 moles of said polycarboxylic acid at a temperature of at least 1 8O0C until the acid number of the resultant unsaturated polyester is less than 55.

2. A method as claimed in claim 1, wherein the unsaturated polyester has a Gardner-Holdt Viscosity of at least H at 30% xylene.

3. A method as claimed in claim 1, wherein the polycarboxylic acid component contains at least 50 mole percent maleic acid.

4. A method as claimed in claim 3, wherein the polycarboxylic acid component is reacted with 60 to 1 60 moles of dicyclopentadiene per 100 moles of said polycarboxylic acid and said reaction product has an acid number less than 250 and contains at least 45 mole percent of the half maleic ester of dicyclopentyl alcohol.

5. A method as claimed in claim 4, wherein the dicyclopentadiene reactant comprises 80 to 120 moles per 100 moles of said polycarboxylic acid.

6. A method as claimed in claim 4, wherein the unsaturated polyester has a Gardner-Holdt Viscosity of at least D at 40% xylene.

7. A method as claimed in any preceding claim, wherein the maleic acid is produced by reaction of maleic anhydride with at least stoichiometric amounts of water prior to reaction with the dicyclopentadiene.

8. Methods of preparing an unsaturated polyester, substantially as described in the foregoing Examples.