IL28844A

IL28844A - Vinyl ester resin compositions and thickened vinyl ester resin compositions

Info

Publication number: IL28844A
Application number: IL2884467A
Authority: IL
Original assignee: Dow Chemical Co
Priority date: 1966-11-07
Filing date: 1967-10-30
Publication date: 1971-02-25
Also published as: DE1720515C3; CH496042A; DK126384B; DE1720515B2; DE1720515A1; NL6715079A; BE706100A; NO128405B; GB1197810A; AT288031B; LU54798A1; SE338159B; ES346795A1; NL152885B; FR1552979A

Description

C O H E N Z E D E K & S P I S B A C H EO D. PAT E NT AT TO RN EYS 24, LEVONTIN STR.. P. O. B. 1169 T E L - A V I V P A T E N T S & D E S I G N S O R D I N A N C E 17093/67 SPECIFICATION IMPROVED VINYL ESTER RESI COMPOSITIONS AND THICKE ED VINYL EST El? RESIN COMPOS TIONS mango «' »*»! toDK na manym οοκ «nm imsiao mangn THE DOW CHEMICAL COIteFANY, a corporation organized and existin under the laws of the State of Delaware, and having an office and place of business at to id land, County of Midland, State of Michigan, U.S.A., DO HEREBY DECLARE ihe nature of this invention and in what manner the same is to be performed to be particularly described and ascertained in and by the following statement : This invention relates to novel thermosetting vinyl ester resin compositions, their preparation and products of the compositions. More particularly it relates to thermosetting resin compositions comprising a blend of (A) up to 70 percent by weight of polymerizable monomer containing a group, and (B) at least 30 percent by weight of vinyl ester resin prepared by reaction of (1) an ethylenically unsaturated mono-carboxylic acid, -(2) a polyepoxide and (3) a dicarboxylic acid anhydride .

The vinyl ester resins are polymerizable low molecular weight resins with a high capacity for inert fillers and reinforcing media. Additional advantages and improvements in these thermosetting resins of special interest to the reinforced plastic industry include higher heat distortion temperatures, better glass wetting, rapid curing and improved surface smoothness and resistance to stress cracking in the cured articles. Other advantages and objects of the invention will be apparent from the following description.

Broadly defined, the vinyl ester resins of the present invention are prepared (1) by contacting a polyepoxide with an ethylenically unsaturated monocarboxylic acid to produce a reaction product which contains, in part, the functional group 0 II I I - c - o - c - c - t I OH produced by the interaction of an epoxide group with a carboxylic acid group, and if desired (2) by further condensation of the secondary hydroxyl groups contained in the above reaction product with a dicarboxylic acid anhydride to produce pendant half ester groups. The resulting vinyl ester resin may then be admixed The present invention also relates to a method to rapidly thicken the thermosetting vinyl ester resins, herein defined, the resulting compositions and articles produced therefrom. More particularly, the rapid thickening is obtained by the admixture of (A) a metal oxide or hydroxide, wherein the metal is selected from Group II of the periodic chart, and (B) a catalytic amount of water, to (C) a vinyl ester resin composition as herein defined.

The thickening of resins useful in preparing reinforced plastic articles frequently may take as long as two weeks or more to reach the physical state desired. All too frequently, the thickening over this period of time is also due to partial polymerization or curing of the resin which is not desired.

Attempts to produce such thickened resins have resorted to the addition to the resin of inert ingredients such as silica aerogel or organic thickening agents. However, such thickened products are tacky, have little strength and reduce the manufacturer's ability to vary the properties of the cured resin.

It has been proposed, for example, in U.S. Patent No. 2,628,209, to incorporate magnesium oxide into unsaturated polyester resins blended with styrene and other polymerizable monomers. While thickening does occur, it is relatively slow even when elevated temperatures are employed. Additionally, the thickening effect was unique to magnesium oxide; other basic oxides or hydroxides were inoperative. It has also been proposed in British Patent No. 949,869 that further improvements can be made by forming Diels-Alder adducts of anthracene and the a, β-olefinically unsaturated dicarboxylic acids used in the preparation of the unsaturated polyester. However, even after a four hour treatment at 70° C. , it still requires about three i i i The present invention thus also encompasses a novel method for rapidly thickening a blend of the vinyl ester resins as herein described by the admixture of a catalytic amount of water in combination with a metal oxide or hydroxide, where the metal is selected from Group II of the periodic chart. Significantly, when no water is present, this rapid thickening does not occur and the resin compositions may remain fluid even after standing for several days. In contrast to the days and even weeks required by the prior art methods of thickening, the thickening action of the present invention frequently occurs in a matter of minutes.

Another feature is that the rapid thickening, in many instances, produces a firm, relatively non-tacky solid which can be stored, handled, cut to size, etc. before the final curing operation. Further, in applications where the vinyl ester resin is utilized without the polymerizable monomer, similar thickening effects are obtained.

Any of the known polyepoxides can be employed in the preparation of the vinyl ester resins of this invention.

Useful polyepoxides are glycidyl polyethers of both polyhydric alcohols and polyhydric phenols, epoxy novolacs, epoxidized fatty acids or drying oil acids, epoxidized diolefins, epoxidized di-unsaturated acid esters, epoxidized unsaturated polyesters and mixtures thereof so long as they contain more than one epoxide group per molecule. The polyepoxides may be monomeric or polymeric.

Within the scope of this invention, a number of polyepoxide modifications can be readily made. It is possible to increase the molecular weight of the polyepoxide by poly-functional reactants which react with the epoxide group and acid, for example, can be reacted with a diepoxide, such as the diglycidyl ether of a bisphenol, in such a manner so as to join two or more diepoxide molecules and still retain terminal epoxide groups. Other polyfunctional reactants include diiso-cyanates, dicarboxylic acid anhydrides and those reactants which contain functional groups which will react with the epoxide grou .

Where polyhydric phenols are selected to prepare the polyepoxide, many structural embodiments are possible. Poly-epoxides prepared from polyhydric phenols may contain the structural group 0 I I where A is -C, -S-, -S-S-, -S- or -S-, or 0, with Rc and I I I J 0 being H or a lower alkyl group such as methyl or ethyl. A particularly suitable group is the polyglycidyl ethers of polyhydric phenols which are best characterized by their average epoxide n value. The average epoxide n value is related to the chain length of the individual polyepoxide molecules and is a measure of the average chain length of all the molecules of the resin. The n value is best described by reference to the following formula H2C- wherein A may be -C- , -S-, -S-S-, -S-, -S- or -0-. The I I R 0 radicals R^, R3 and may be H or a halogen and R5 and Rg may be H or a lower alkyl group such as methyl or ethyl.

In the formula, n is an integer from 0 to 20 or even higher, but since the polyepoxide resin consists of a mixture of molecules, some where n=0, some where n=l or even higher, the calculated value of n for the resin is usually a fractional number rather than an integer. This calculated n value for a polyepoxide resin is called, for purposes of this invention, the average epoxide n value.

The n value is readily calculated from the analytically determined epoxide equivalent weight. Theoretically, when ne0, the polyepoxide molecule has a molecular weight of about 340 (when A=isopropylidene; R-^, R£, R3 and R^ are H) and an epoxide equivalent weight of 170. When n=l, the molecular weight increases to about 624 and an epoxide equivalent weight of 312. There is a difference of about 142 in the equivalent weight when n is increased from 0 to 1 and this increment can be used to calculate the average epoxide n value for the resin. For example, if a polyepoxide of the above specific formula has an epoxide equivalent weight of 190, the calculated average epoxide n value is 20/142 = 0.14. Analogous calculations can be made for other polyepoxides having the above general formula.

These polyglycidyl ethers of polyhydric phenols, having the formula above, with an average epoxide n value ranging from 0.20 to 2.0 are the preferred polyepoxides. These polyepoxides are usually made by reacting at least about two moles of an epihalohydrin with one mole of the polyhydric phenol, and a sufficient amount of an alkaline compound to combine with the halogen of the halohydrin. The choice of novolac resins leads to a separate well recognized class of epoxy novolac resins.

Further, it is well recognized that flame retardancy properties can be obtained by the introduction of phosphorus and halogen into the epoxy resin itself or by the selection of fillers, extenders, curing agents and the like which contribute to the flame retardant properties. For example, high levels of bromine can be introduced into the resin by the use of tetra-bromo bisphenol A.

The polyepoxides referred to as epoxidized diolefins, epoxidized fatty acids, etc. are generally made by the known peracid method where the reaction is one of epoxidation of compounds with isolated double bonds at a controlled temperature so that the acid resulting from the peracid does not react with the resulting epoxide group to form ester linkages and hydroxyl groups. Preparation of polyepoxides by the peracid method is described in various periodicals and patents and such compounds as butadiene, ethyl linoleate, polyunsaturated drying oils or drying oil esters can all be converted to polyepoxides.

While the invention is applicable to polyepoxides generally, preferred polyepoxides are glycidyl polyethers of polyhydrin alcohols or polyhydric phenols having weights per epoxide group of 150 to 2000. These polyepoxides are usually made by reacting at least about two moles of an epihalohydrin or glycerol dihalohydrin with one mole of the polyhydric alcohol or polyhydric phenol, and a sufficient amount of a caustic alkali to combine with the halogen of the halohydrin. The products are characterized by the presence of more than one epoxide group, i.e., a 1,2-epoxy equivalency greater than one.

Ethylenically unsaturated monocarboxylic acids suitable for reaction with the polyepoxide include the α,β-unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid and cinnamic acid. The hydroxyalkyl group of the acrylate or methacrylate half esters preferably contains from two to six carbon atoms and includes such groups as hydroxy-ethyl, beta-hydroxypropyl and beta-hydroxybutyl. It is also intended to include those hydroxyalkyl groups in which an ether oxygen is present. The dicarboxylic acids can be either saturated or unsaturated. Saturated acids include phthalic acid, chlorendic acid, tetrabromophthalic acid, adipic acid, succinic acid and glutaric acid. Unsaturated dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, ita-conic acid, halogenated maleic or fumaric acids and mesaconic acid. Mixtures of ethylenically unsaturated carboxylic acids may be used.

Preferably, the half esters are prepared by reacting substantially equal molar proportions of a hydroxyalkyl acrylate or methacrylate with a dicarboxylic acid anhydride. Preferred unsaturated anhydrides include maleic anhydride, citraconic anhydride and itaconic anhydride and preferred saturated anhydrides include phthalic anhydride, tetrabromophthalic anhydride and chlorendic anhydride. Advantageously, a polymerization inhibitor, such as the methyl ether of hydroquinone or hydro-quinone, may be added since elevated temperatures are useful in preparing the half esters. The reaction temperature may range from 20° to 150° C. but preferably from 80° to 120°C.

The polyepoxide is reacted with the ethylenically unsaturated monocarboxylic acid either with or without a solvent at a temperature of 20° to 120° C. The reaction may also be conducted in the presence or absence of suitable catalysts such as alcoholates, tertiary amino phenols or others well known to the art. Preferabl the ol e oxide is added in an amount sufficient to provide 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid. The reaction is continued until the acid content (as -C00H) drops below 2 percent by weight.

The ethylenically unsaturated monocarboxylic acid-polyepoxide reaction product containing secondary hydroxyl groups may further be reacted with 0.1 to 1.2 mole proportions of dicarboxylic acid anhydride per equivalent of epoxide. The dicarboxylic acid anhydride may be selected from either the saturated or unsaturated dicarboxylic acid anhydrides previously recited or mixtures thereof. A reaction temperature from 25° to 150°C. is suitable, but 80° to 120°C. is preferred. Advantageously, a suitable vinyl polymerization inhibitor such as the methyl ether of hydroquinone or hydroquinone and the like may be added. Following completion of the reaction, the reaction mixture is cooled and the polymerizable monomer may be blended therewith.

A wide selection of polymerizable monomers containing the group is available from the many known classes of vinyl monomers. Representative species are the vinyl aromatic compounds which include such monomers as for example styrene, vinyl toluene, halogenated styrenes and divinyl benzene.

Other valuable monomers include the methyl, ethyl, isopropyl and octyl, esters of acrylic or methacrylic acid, vinyl acetate, diallyl maleate, dimethallyl fumarate, acidic monomers such as acrylic acid, methacrylic acid, crotonic acid and amide monomers such as acrylamide and N-alkyl acrylamides and mixtures thereof.

Preferred polymerizable monomers containing the ^> C=CH2 group are styrene, vinyl toluene, ortho-, meta- and para-halostyrenes , vinyl naphthalene, the various alpha-substituted styrenes, as well as the various di- , tri- and esters which include both the saturated alcohol esters and the hydroxyalkyl esters.

The highly desirable property of rapid thickening referred to above is obtained when finely divided magnesium oxide and a catalytic amount of water are admixed with a blend of the vinyl ester resin containing reactive carboxylic acid groups and a polymerizable monomer containing group. The admixture of magnesium oxide without water with the vinyl ester resin composition, as previously proposed, was not successful in producing rapid thickening, but only resulted in a slight increase in the fluid viscosity. The critical and unexpected role of water was demonstrated using a resin composition which previously had resulted in only a slight viscosity increase upon the addition of MgO, whereby the addition of water to this same composition caused thickening in a matter of a few minutes.

The proportions of magnesium oxide and water in relation to the reactive carboxylic acid content of the resin composition influence the rate of thickening. It has been found by experiment that at least 0.75 equivalents of magnesium oxide (one molecular weight of MgO equals two equivalents) per equivalent of carboxylic acid (-C00H) and 0.25 equivalents of water (one molecular weight equals one equivalent) are necessary to achieve rapid thickening. Increasing the above ratios through the range of 1/1 to 5/1 equivalents per equivalent of -C00H greatly improves the thickening rate. Below this ratio of 1/1, the time for thickening to occur is progressively dramatically increased. Above the ratio of 5/1, the rate approaches a constant value. For rapid thickening, it is pre-ferred to utilize one to five equivalents of magnesium oxide er e uivalent of -C00H and one to five e uivalents of water per equivalent of -COOH. For minimum tack characteristics of the thickened resin composition, a similar ratio of 1/1 to 5/1 equivalents of magnesium oxide or water per equivalent of -COOH is preferred.

Other metal oxides and hydroxides perform in a like manner to magnesium oxide. The oxides of calcium and zinc and the corresponding hydroxides of calcium and magnesium in combination with water result in rapid thickening. Of the group of metal oxides and hydroxides wherein the metal is selected from Group II of the periodic chart, magnesium oxide is preferred.

The thickening action is a function of temperature.

As the temperature is increased above normal room temperature, the rate of thickening becomes more rapid until at 80°C. , the thickening rate approaches a constant value. While thickening does occur at room temperature, the preferred temperature range is 40°-70°C.

Additionally, the concentration of free carboxylic acid groups influences the rate of thickening and this concentration can be varied by the amount of polymerizable monomer blended with the vinyl ester resin, by the proportions of dicar-boxylic acid anhydride used in the last stage of the vinyl ester resin preparation, or by utilizing polyepoxides with varying equivalent weights.

A series of resins was prepared and blended with styrene to a concentration of 40 percent by weight styrene, wherein the reactive carboxylic acid concentration was varied from 0.9 to 4.2 percent (-C00H) by weight. A dramatic decrease in the time for thickening to occur was found as the concentration of carboxylic acid groups increased, with the rate approach-ing a constant value in the range of carboxylic acid concen The blended vinyl ester resin composition may consist of up to 70 percent by weight of polymerizable monomer containing the group with the balance of the combined weight consisting of said vinyl ester resin. Preferably, the resin composition consists of 30-60 percent by weight of said monomer and 70-40 percent by weight of said vinyl ester resin- While it is preferred in many applications to blend the vinyl ester resin with a polymerizable monomer, the present invention is not limited thereto. The vinyl ester resin can be cured and polymerized in the absence of such a monomer and can be applied and utilized as solutions in a non-polymerizable solvent, such as is practiced in certain coating operations.

According to the present invention, the curing of the resin compositions is effected by the application of heat and/or pressure in the presence of a free radical yielding catalyst. Catalysts that may be used for the curing or polymerization are preferably the peroxide catalysts, such as benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, t-butylper-benzoate, methyl ethyl ketone peroxide and potassium persulfate. The amount of the catalyst added will preferably vary from 0.1 percent to 5 percent by weight of reactants. Temperatures employed may vary over a considerable range but usually are in the range of 20° to 250°C.

Additionally, more rapid curing of the thermosetting resin compositions may be accomplished by the addition of accelerating agents such as lead or cobalt naphthenate and dimethylaniline, usually in concentrations ranging from 0.1 to 5.0 weight percent.

The relatively low molecular weight of the vinyl ester resins of the present invention along with the rapid gel setting resin compositions provide many advantages and improved properties in a wide variety of applications.

Pottings and castings are conveniently made by the addition of suitable curing agents and accelerating agents to the resin composition followed by pouring into an appropriate mold or casting and curing at room temperature. Heat may be applied to accelerate the cure. Such cured castings have excellent flexural and tensile strength, good impact resistance and develop smooth, hard surfaces.

In addition, the resultant lower viscosity of said resin compositions allows the incorporation of up to as much as 75 percent by weight or more of inert additives and fillers such as glass, metal filings and inorganic fillers such as sand or clay. The resin compositions, in spite of this heavy loading exhibit excellent flow characteristics in the molding operation. Frequently such fillers are added to further improve and vary the useful properties of the cured compositions. Such cured products develop excellent hardness, strength, weatherability and solvent resistance. Other commonly used additives, such as pigments, release agents and plasticizers may be advantageous added.

Of particular utility is the use of the present invention in the preparation of reinforced plastic and laminate structures. Reinforcing media may be chosen from many well known suitable materials such as glass cloth and matting, paper, asbestos paper, mica, and fabrics. Suitable fillers, previously described, are frequently used to provide improved properties. For example, clays are suggested where improved exterior weather ing properties are required. In addition to the advantages and improved properties already recited, this invention provides than unsaturated polyester resins. A particular feature of the preferred compounds described above relates to the high loadings of inert fillers such as kaolin clay, which can be admixed with these vinyl ester resin compositions. This feature, or clay acceptability level, is readily observed whereby as higher levels of clay are added to the said resin composition, a point is reached wherein the mixture of clay with the resin composition is no longer fluid but it becomes intractable.

As previously described, the clay acceptability is dependent on the average epoxide n value for the polyepoxide or polyepoxide mixture used in preparing the vinyl ester resins. Within the n value range of 0.20 to 2.0, loadings of inert fillers as high as 70 to 75 percent by weight of the formulation may be obtained. A more preferred range of n values for the polyepoxide or polyepoxide mixture is 0.25 to 1.75. It is to be understood that the polyepoxide mixture may comprise more than two resins.

Using suitable mixing or blending means, the thickened thermosetting vinyl ester resin compositions are generally prepared by (1) admixture of the variously-recited additives, with the exception of the thickening agents, to the vinyl ester resin, followed by (2) admixture of the thickening agents, the metal oxide or hydroxide and water. Preferably, in the first stage, the vinyl ester resin is blended with the polymerizable monomer followed by admixture of the catalyst and other additives, such as for example inert fillers, glass fibers, pigments, accelerating agents, mole release agents. Elevated temperatures may be used but, preferably, the mixing is performed at room temperature. A range of temperatures may be used in the second stage, but preferably, the mixture is heated to 40° to 70°C. add the metal oxide or hydroxide at the first stage and obtain the thickening action by the addition of water, only, at the second stage. Those skilled in the art will recognize that other modifications of the method of preparation are possible without departing from the scope of the invention.

The time of thickening, as described in this application, was determined by the following test procedure: A high speed, low torque, air-driven stirrer (Aero Mix, Junior Model, Catalogue No. 65777, Precision Scientific Company, Chicago, Illinois) was used to mix the appropriate ingredients in a container, usually an 8 ounce/237 ml. glass bottle, which may be preheated and maintained at a preset temperature by positioning in a temperature controlled water bath. Most tests were conducted at 70°C. After the final addition of ingredients, the thickening time was observed and the time required to reduce the speed of stirring to one revolution per second was measured. Typically, 100 grams of, for example, styrene-blended resin was placed in an 8 ounce bottle and preheated to 70°C. The appropriate amount of metal oxide or hydroxide was added and blended for one minute with the stirrer set at 2000 rpm. followed by the addition of an appropriate amount of water. The time of thickening was then measured. Test results were found to be very reproducible.

A viscosity relationship to the test end point (one revolution per second) was established by viscosity determina-tions on the resin and by calibration with other fluids. The viscosity at 70°C. at the above end point ranges from 30,000 to 40,000 centipoise. Upon cooling and standing, many of these thickened resin compositions develop viscosities of over 9 x 10^ centipoise.

The tack- free time was determined in a somewhat except a high speed, high torque stirrer (Gast Manufacturing Corporation, Model #1-AM-NCW-14, Benton Harbor, Michigan) set at 3000 rpm. was used. The MgO was blended for one minute before the water addition. Ten seconds after the water is added, stirring is stopped and tackiness determined at 15 second intervals by inserting a wooden tongue depresser into the resin composition. The tack-free time is the time needed for the resin to become sufficiently tack-free so that it will not stick to the end of the wooden tongue depresser. This test also had good reproducibility.

These tests and others to be defined were used in determining the information in the following examples which illustrate, without limitation, methods of carrying out the present invention.

For purposes of illustration, the examples shown below are presented. In the examples 6 and 7 Polyepoxide Resin A is a diglycidyl ether of 4, 1 -isopropylidene diphenol having an average epoxide n value of about 2.6 and an epoxide equivalent weight of about 540. Polyepoxide Resin B is a diglycidyl ether of 4,4' -isopropylidene diphenol having an average epoxide n value of about 0.14 and an epoxide equivalent weight of about 190. EXAMPLE 1 Into a reaction vessel suitably equipped with a means for stirring, refluxing, temperature control, etc. were placed 4.06 pounds/1.84 kg. of beta-hydroxyethyl aerylate and 5.18 pounds/2.35 kg. of phthalic anhydride. The vessel was heated to 80°C. for one-half hour and then maintained at 115 °C. until the acid content (as -C00H) was about 17.5 percent by weight (about three hours). After cooling to 60°C. , 6.12 pounds/2.68 kg. of a diglycidyl ether of 4,4 ' -isopropylidene diphenol (having DMP-30 (2,4,6-tri(dimethylaminomethyl)phenol) were added. The reaction mixture was digested at 110°C. until the acid content dropped to 1 percent by weight (about two and two-thirds hours). After cooling to 60°C, 3.43 pounds/1.55 kg. of maleic anhydride was added along with 12.807 grams of mono-tertiarybutyl hydro-quinone. The reaction mixture was digested at 100°C. until the acid content was about 10 percent by weight (about one hour). This corresponds to about a 100 percent conversion of alcohol groups to pendant maleate half ester groups. The reaction product was cooled to 60°C. and 18.8 pounds/8.52 kg. of styrene blended therewith.

A portion of this resin was mixed with 1 percent by weight of benzoyl peroxide and cured at 250°F. (121°C. ). The following SPI gel data was obtained (reference, Handbook of Reinforced Plastics of the Society of the Plastics Industry, Inc., Reinhold Publishing Corp., New York, 1964, p. 51 and 52) Gel Time 0.98 minutes Peak Time 1.95 minutes Peak Temperature 588°F. (267°C.) A clear casting was prepared using benzoyl peroxide as the catalyst and tested according to industry standards with the results shown below.

Flexural strength 16,900 psi./1188 kg/cm2 Tensile strength 8,400 psi./590 kg/cm2 Heat distortion 235°F. (113°C.) Toluene absorption 0.007% Water absorption 0.174% Similar results are obtained when the pendant half ester groups are formed by reaction with phthalic anhydride in place of maleic anhydride.

EXAMPLE 2 Into a reaction vessel suitably equipped with a means for stirring, refluxing, temperature control, etc. were placed 232 grams (2 moles) of beta-hydroxyethyl acrylate and 196 grams (2 moles) of maleic anhydride. The vessel was heated to 100°C. and allowed to react at that temperature until the acid content was about 21 percent by weight (as -COOH). Then, 350 grams of diglycidyl ether of 4, 1 -isopropylidene diphenol (having an epoxide equivalent weight of about 175), 2 grams of DMP-30 and 0.112 gram of hydroquinone were added. The vessel was heated and maintained at 100°C. until the acid content dropped to about 1 percent by weight. After cooling to 60°C, 117.6 grams (1.2 moles) of maleic anhydride were added and then digested at 100°C. for about two to three hours. This corresponds to about a 60 percent conversion of alcohol groups to pendant maleate half ester groups. The reaction product was then cooled to 70°C. and 1347 grams of styrene was blended therewith.

Similar resins are obtained when the beta-hydroxyethyl acrylate is reacted with phthalic anhydride in place of maleic anhydride .

EXAMPLE 3 In a 10 gallon/38 liters stainless steel vessel equipped with an agitator, a reflux condenser, temperature control, etc. were placed 16.32 pounds/7.39 kg. of cinnamic acid, 19.84 pounds/8.99 kg. of D.E.N. 438 (registered Trade Mark) a commercially-available epoxy novolac resin having an epoxide equivalent weight of about 178), 22.5 milliliters of DMP-30 and 1.82 grams of hydroquinone. The vessel was heated to 105°C. and held thereat for about 10 hours. After cooling to 60°C, 3.6 pounds/1.63 kg. of maleic anhydride were added ° corresponds to about a 30 percent conversion of alcohol groups to pendant maleate half ester groups. After cooling, 39.76 pounds/18.11 kg. of styrene were blended with the vinyl ester resin.

SPI Gel Data at 250°F. (121°C.) (1% by Wt. Benzoyl Peroxide) Gel Time 1.81 minutes Peak Time 2.50 minutes Peak Temperature 434°F. (223°C.) The physical properties of this resin cured with 1 percent by weight benzoyl peroxide at 80°C. overnight and for 45 minutes at 121°C. were as follows: Flexural strength 11,700 psi./832 kg. /cm' Flexural modulus 4.64 x 105 psi./32622 kg. /cm^ Barcol hardness 43 Heat distortion 230°F. (110°C. ) EXAMPLE 4 In a reaction vessel equipped with a means for stirring, refluxing, temperature control, etc. were placed 6.5 pounds/2.9 kg. of acrylic acid, 17.5 pounds/7.9 kg. of diglycidyl ether of !0 4,4 ' -isopropylidene diphenol (having an epoxide equivalent weight of about 175) and 19.9 grams DMP-30. The mixture was heated at 100°C. until the acid content was about 1 percent by weight.

After cooling, 9.8 pounds/4.4 kg. of maleic anhydride and 18.4 grams of monotertiarybutyl hydroquinone were added. The mixture !5 was then heated at 100°C. for about two hours. This corresponds to about a 100 percent conversion of alcohol groups to pendant maleate half ester groups. The product was then cooled and blended with 33.8 pounds/15.3 kg. of styrene.

Portions of this resin were mixed with 1 percent by >0 weight benzoyl peroxide and the following physical properties SPI Gel Data at 250°F. (121°C.) Gel time 0.88 minute Peak time.... 1.49 minutes Peak temperature 577°F. (303°C.) Cured Castings 2 Flexural strength 12,100 psi./851 kg. /cm 2 Tensile strength 7,350 psi./517 kg. /cm Heat distortion....... 303°F. (151°C. ) Water absorption..... 0.22% Toluene absorption 0.14%, Similar results are obtained when methacrylic acid is utilized in place of acrylic acid.

EXAMPLE 5 A resin similar to that of Example 3 was prepared using beta-hydroxypropyl aerylate in place of beta-hydroxyethyl aerylate and curable compositions were prepared in which the styrene was replaced by vinyl toluene, ortho-chlorostyrene and methyl methacrylate .

EXAMPLE 6 Into a reactor at 80°C. and equipped with means for agitation, temperature control and the like were added 7.26 pounds/3.3 kg. of acrylic acid and 26.74 pounds/12.1 kg. of Polyepoxide Resin A. After the contents were digested for about 20 minutes, 9.54 pounds/4.3 kg. of Polyepoxide Resin B, 49.4 milliliters of DMP-30 (2 ,4,6-tri (dimethylaminomethy1)phenol) and 2.0 grams of hydroquinone were added and the temperature raised to 100°-105°C. The contents were then digested until the percent -C00H dropped to about 1 percent by weight. The reactor was then cooled to 60°C. and 43.5 pounds/19.7 kg. of styrene added and blended. The product was then cooled, filtered, u d d i l i m i io ad a viscosity of 125 cps. at 25°C. and was a straw-colored clear liquid. The average epoxide n value for the mixture of poly-epoxides used in this example was calculated to be 1.370.

Cure rates were determined on portions of the above resin composition by adding 1 percent by weight benzoyl peroxide and heating at the specified temperature.

Q 180°F./82.5°C. @ 250°F./121°C.

Gel time 8.5 min. 1.33 min.

Peak time 12.5 min. 2.20 min.

Peak temperature 383°F. 440°F.

Clear castings were also made using 1 percent by weight benzoyl peroxide as catalyst and curing at 80°C. overnight and post-curing at 250°F. /121°C. for 45 minutes, with the following results: Flexural strength. 17 ,550_psi. /1234 kg. /cm Flexural modulus 4.27 x 10** psi./ 30021 kg. /cm2 Barcol hardness 35 Heat distortion temperature 213 °F.

Toluene absorption. 1.947% Water absorption 0.0162% Using a commercially-available kaolin clay (Hydride R), the clay acceptance of the resin composition was determined to be 67-70 percent, i.e., the final formulation may comprise up to 67-70 percent by weight clay and 33-30 percent by weight of the vinyl ester resin composition.

It was not possible to prepare a resin according to this invention from Polyepoxide A alone.

EXAMPLE 7 By the method of Example 6, a series of resins was The resin compositions and their percent clay acceptance are tabulated below.

F083-' 00 Example Acid Polyepoxide Polyepoxide Number (1 Equiv. ) A B Η» v£> H* 7a acrylic 1 equiv. 7b methacrylic 7c acrylic 0.1 equiv. 0.9 7d Π 0.1 0.9 " 7e If 0.2 M 0.8 " 7f II 0.3 " 0.7 11 tl 7g 0.5 0.5 " 7h methacr lic 0.5 0.5 " 1 7i II N> 0.23 " 2) 0.77 " NJ 1 (1) A diglycidyl ether of 4,4' -isopropylidene diphenol having n value of about 0 and an epoxide equivalent weight of ab (2) A diglycidyl ether of 4,4 ' -isopropylidene diphenol having n value of 5.4 and an epoxide equivalent weight of about The above resins (7a to 7i) can be readily cured by the addition of about 1 percent by weight benzoyl peroxide and applying heat such as by a molding press, for example. The cured resins are hard, have excellent resistance to water and a variety of solvents and have excellent tensile and flexural strength. The resins can also be readily admixed with glass fibers to produce laminates and other reinforced plastic objects. Other additives commonly used in the resin formulations may also be used, additives such as release agents, colorants, pigments and the like.

Various other properties or modifications are readily made with these vinyl ester resins. Self-extinguishing or flame retardant properties may be obtained by the appropriate choice of a polyepoxide or by the addition of other additives to the formulation such as phosphorus compounds, antimony oxide and the like. Likewise, other reactive components may also be included with the vinyl ester resins to produce particular properties or characteristics, components such as other compatible polymerizable or thermosetting resins, dicarboxylic acids or their anhydrides when they exist, thickening agents and mixtures thereof.

Example 7 clearly shows the improved clay acceptance of vinyl ester resins produced according to this invention.

EXAMPLE 8 A. Into a reaction vessel equipped with a means for stirring, temperature control, refluxing, etc. were placed 13 lbs. /5.9 kg. of β-hydroxyethyl acrylate, 10.65 lbs./4.8 kg. of maleic anhydride and 5.45 grams of mono-tertiarybutyl hydro-quinone which serves as a polymerization inhibitor for the acrylate. The temperature was raised to 80°C, maintained at 80° for 30 minutes and then raised to 115 °C and held thereat to 60°C, 19 lbs./8.6 kg. of a diglycidyl ether of 4,4'-isopro-pylidene diphenol (having an epoxide equivalent weight of about 175) was added along with 43.1 grams of DMP-30 (2,4,6-tri(dimethyl-aminomethyl)phenol) . The temperature was raised to 110°C. and held at that temperature for such time until the percent acid (as -COOH) was 0.52 percent. After cooling to 73°C, 5.33 lbs./ 2.4 kg. of maleic anhydride were added, the temperature raised to 100° C. and the reaction allowed to digest for about three hours to complete the reaction. At the conclusion of the reac-tion, the resin contained about 5.53 percent acid (-C00H) corresponding to about a 50 percent conversion of secondary hydroxyl groups to pendant maleate half ester groups. This resin, after cooling to 60°C, was blended with 32 lbs./14.5 kg. styrene to give a final composition of 40 percent by weight styrene and 60 percent by weight of the above reaction product with an acid content of 3.3 percent (-C00H). Hereinafter, this resin will be called Resin C.

B. By the same procedure as above, a series of resins with different acid concentrations was prepared by varying the amount of maleic anhydride used in the last stage of the reaction by which the secondary hydroxyl group is converted to a pendant half ester group. The resins, including Resin C, are described below in Table I and all contain 40 percent by weight styrene.

Table I Weight Percent Moles of Maleic Resin Acid (as -COOH) Anhydride Used Resin C 3.3 0.5 Resin D 0.9 0.2 Resin E 2.1 0.35 Resin F 4.2 0.65 Resin G 6.5 0.95 In each case, the moles of maleic anhydride used correspond to the approximate percent conversion of secondary hydroxyl groups to pendant half ester groups, e.g., Resin C (0.5 mole maleic anhydride) corresponds to 50 percent conversion; Resin E (0.35 mole maleic anhydride) corresponds to 35 percent conversion.

C. Several of the resins were prepared to contain 1 percent by weight benzoyl peroxide and were then thickened by the addition of two equivalents of MgO and one equivalent of water. Cured castings were made from these resins and tested for physical properties with the results shown in Table II.

Table II Resins Casting Properties Resin D Res Flex strength2at 77°F./25°C. 18,500/1301 14,6 ppssii.. //kKgg.. //ccmm',, ^1) and after 2 hr. water boil 13,300/935 15,0 Flex modulus, at 77°F./25°C. 4.88 (x 105), U } and after 2 hr. water boil 4.67 (2) Heat distortion temperature °F./°C. ' 211/99 2 Toluene absorption 24 hr. , 0.02 Water absorption 24 hr., %^ 0.17 Tensile, psi. /kg. /cm2 (4) 9,500/668 6,9 Elongation, 2.4 (^by ASTM D790-59T ^by ASTM D648-56 ^3^by ASTM D570-59aT ^b ASTM D638-58T Another formulation was made by blending one part of kaolin clay with one part of a resin prepared in a manner similar to Resin C except that hydroxypropyl acrylate was employed instead of hydroxyethyl acrylate and the polymerization inhibitor employed was hydroquinone instead of mono-tertiarybutyl hydroquinone and containing 1 percent by weight benzoyl peroxide, and then adding a mold release agent and two equivalents of MgO. After thorough mixing, 75 parts of this formulation were blended with 25 parts of 1/4 inch/0.64 cm. glass fiber, wherein the glass fibers became evenly coated in about one minute due to the excellent glass wetting characteristics. The glass reinforced formulation was then allowed to thicken at room temperature. It was found that the water present in the clay was sufficient to catalyze the thickening action. The finished formulation was notable for its "dryness" or lack of tack and could be separated into small pieces or retained as larger segments or mats as desired. The formulation also molded very well, filled out the die completely and the glass was distributed evenly throughout the cured article.

EXAMPLE 9 Using Resin A, an attempt was made to thicken the resin by the admixture of magnesium oxide at various temperatures using different types of stirring. While some slight viscosity increases were noted, no appreciable thickening action occurred and no solid products produced.

The above test was repeated wherein the resin was heated to 70°C. and two equivalents of magnesium oxide per equivalent of -C00H were added. After blending for 60 seconds, one equivalent of water per equivalent of -C00H was added.

Within 15 seconds (after blending with the water), noticeable cooling, the resin composition was firm and tack-free, yet could be softened and molded simply by heating. Although the rate of thickening is somewhat slower than for MgO, similar thickening effects were observed when the magnesium oxide was replaced with zinc oxide, calcium hydroxide, magnesium hydroxide or calcium oxide.

EXAMPLE 10 By means of the previously-defined thickening time test, the effect of the number of equivalents of magnesium oxide per equivalent of -C00H was determined using Resin D.

Equivalents of Mg0/-C00H varied from 0.8/1.0 to 2.0/1.0 and the tests were run at 70°C. with one equivalent of water per equivalent of -C00H present in all cases. A dramatic decrease in time of thickening occurred as the equivalents of Mg0/-C00H approached 1/1. The results are summarized in Table III.

Table III Equivalents of MgO Per Equivalent of -C00H 0.8/1 0.9/1 1/1 1.5/1 2/1 Thickening time, minutes 20 2 3/4 1 1/2 3/4 1/2 In a similar manner, the effect of higher loadings of MgO was determined with Resin C by varying the equivalents of MgO/-COOH from 4/1 to 8/1. The results are summarized in Table IV.

Table IV Equivalents of MgO Per Equivalent of -C00H 4/1 8/1 Thickening time, minutes 1/4 1/4 The following example demonstrates that somewhat similar results were found when the equivalents of water were varied while holding the equivalents of MgO constant.

EXAMPLE 11 In addition to ra id thickenin an im ortant feature tack-free thermoplastic solids.

By means of the tack-free test previously cited, the effect of the number of equivalents of water per equivalent of -C00H (H20/-C00H) was evaluated. The results shown in Table V were obtained with a resin similar to Resin A at a temperature of 80° C. and with two equivalents of magnesium oxide per equivalent of -C00H present in all cases.

Table V Equivalents H?0/Equivalents -C00H 0.5/1 1/1 2/1 3/1 4/1 Tack-free time, minutes 3 1/4 2 1/2 2 1/4 2 3/4 3 3/4 An optimum was noted at about a 2/1 ratio of H2O/-COOH.

EXAMPLE 12 By blending Resins B and D, resins were prepared wherein the acid concentration was varied from about 0.9 percent to 4.2 percent and the thickening time as a function of percent acid content (-C00H) was evaluated. All tests were made with two equivalents of magnesium oxide per equivalent of -C00H, one equivalent of water per equivalent of -C00H and the resin composition heated to 70° C. A decrease in thickening time was found as the percent acid content (-C00H) increased up to 2 to 3 percent. Additional improvement in the thickening rate occurred as the concentration of carboxylic acid was increased above 3 percent. Preferably, the carboxylic acid content should be above 2 percent by weight.

When the maleic anhydride used in the final stage of the preparation of the resins of Example 1 is replaced with phthalic anhydride (in an amount sufficient to obtain a 40 percent conversion of the hydroxyl groups), similar thickening characteristics are obtained.

EXAMPLE 13 compositions : (a) The resin prepared from a maleate half ester of beta-hydroxypropyl acrylate and the polyepoxide of Example 1 followed by reaction with phthalic anhydride and then blended with styrene. (b) The resin (a) above where methyl methacrylate is used in place of styrene. (c) The resin (a) above where vinyl toluene is used in place of styrene. (d) The resin (a) above where ortho-chlorostyrene is used in place of styrene. (e) The resin prepared from acrylic acid and the polyepoxide of Example 1 followed by reaction with maleic anhydride and then blended with styrene. (f) The resin (e) above where methacrylic acid is used in place of acrylic acid. (g) The resin prepared from a maleate half ester of beta-hydroxyethy1 acrylate and D.E.R. 736, (registered Trade Mark) a commercially available diglycidyl ether of a polyglycol having an epoxide equivalent weight of 175-205 followed by reaction with maleic anhydride and then blended with styrene.

The resin compositions of the present invention are of value in the preparation of pottings and castings and in the formation of various shaped articles. In the preparation of castings and pottings from these resin compositions, it is desirable to add a curing agent before the addition of the water and the said metal oxide or hydroxide without the application of elevated temperatures. It is then possible to pour the mixtures into the mold or casting and apply heat to accelerate the polymerization. The cured resin compositions have excellent tensile and flexural stren th and solvent-resistant ro erties.

Self-extinguishing or flame retardant properties can be obtained with the resins of this invention by the introduction of halogens or phosphorus and the like into the resins by well known means. For example, such properties can be incorporated into the vinyl ester resin itself by the use of a tetrabromo bisphenol in the preparation of a polyepoxide.

In addition, the resin compositions of the present invention are valuable in the preparation of laminating compositions which may be applied to for example glass, wood, cloth and paper.

Claims

HAVING WOW par icularly described and ascer- —-tained the nature of our aaid invention and xn wtiat manner the same is to be performed, we Geciare that ha t we claim is : THE.vE BQlilMEHTS AQE EHE INVENTION. IN WHICH AN EXCLUS IVEAKRQEERTX SRAERIVII-RGE .IS XbKSfflb&' R®. OEETMX ASXFOLLOWS*

1. A thermoset ing resin composition comprising (A) at least 30 percent by weight of a vinyl ester resin wherein the resin is prepared by (1) first reacting an ethylenically unsaturated monocarboxylic acid with a polyepoxide, and if desired (2) reacting a dicarboxylic acid anhydride with the secondary hydroxyl groups formed from the epoxide-carboxylic acid reaction to provide pendant half ester groups, said reactants combined in the proportion of about 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid and about 0.1 to 1.2 moles of dicar-boxylic acid anhydride per equivalent of epoxide; and (B) up to 70 percent by weight of a polymerizable monomer containing a ^ C=CH2 group .

2. The composition of Claim 1 wherein the ethylenically unsaturated monocarboxylic acid is a member of the group consisting of acrylic acid, methacrylic acid and cinnamic acid.

3. The composition of Claim 1 wherein the ethylenically unsaturated monocarboxylic acid is the hydroxyalkyl acrylate or methacrylate half ester of a dicarboxylic acid.

4. The composition of Claim 3 wherein the half ester is a maleic acid half ester.

5. The composition of Claim 3 wherein the half ester is a phthalic acid half ester.

6. The composition of Claim 1 wherein the polyepoxide is a glycidyl polyether of a polyhydric alcohol.

7. The composition of Claim 6 wherein the polyepoxide is the glycidyl polyether of 4,4' -isopropylidene diphenol.

8. The composition of Claim 6 wherein the polyepoxide is an epoxy novolac. »

9. The composition of Claim 1 wherein the dicarboxylic acid anhydride is a member of the group consisting of phthalic anhydride and maleic anhydride.

10. The composition of Claim 1 wherein the poly-merizable monomer is selected from the group consisting of vinyl aromatic monomers, hydroxyalkyl esters of acrylic and methacrylic acid, alkyl esters of acrylic and methacrylic acids, acrylic and methacrylic acid.

11. The composition of Claim 1, wherein the poly-epoxide is a polyglycidyl ether of a polyhydric phenol having an average epoxide n value of 0.20 to 2.0.

12. The composition of Claim 1, wherein the poly-epoxide is a mixture of at least two polyglycidyl ethers of polyhydric phenols wherein the average epoxide n value of the mixture is 0.20 to 2.0.

13. The composition of Claim 11, wherein the n value ranges from 0.25 to 1.75.

14. A thermosetting resin composition which comprises the product of reaction of (A) an α, -unsaturated monocarboxylic acid with (B) a polyepoxide wherein the polyepoxide is a polyglycidyl ether of a polyhydric phenol having an average epoxide n value of 0.20 to 2.0 or a mixture of two or more polyglycidyl ethers of polyhydric phenols wherein the average epoxide n value of the mixture is 0.20 to 2.0; said polyepoxide added in an amount to provide about 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid.

15. The composition of Claim 14 wherein the n value ranges from 0.25 to 1.75 in each instance.

16. A thermosetting resin composition which comprises a mixture of (A) a blend of (1) up to 70 percent by weight of a polymerizable monomer containing a group, and (2) at least 30 percent by weight of a vinyl ester resin prepared (a) by reacting an ethylenically unsaturated mono-carboxylic acid with a polyepoxide, and then (b) reacting a dicarboxylic acid anhydride with the secondary hydroxyl groups formed from the epoxide-carboxylic acid reaction to provide pendant half ester groups; said reactants combined in the proportion of 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid and 0.1 to 1.2 moles of dicarboxylic acid anhydride per equivalent of epoxide; and (B) a metal oxide or hydroxide, wherein the metal is selected from Group II of the periodic chart, in an amount sufficient to provide at least 0.75 equivalents per equivalent of carboxylic acid (-C00H); and (C) a catalytic amount of water in an amount sufficient to provide at least 0.25 equivalents per equivalent of carboxylic acid (-C00H).

17. The composition of Claim 16 wherein the metal is magnesium, calcium or zinc.

18. The composition of Claim 16 wherein the equivalents of water vary from one to five.

19. The composition of Claim 16 wherein the equivalents of metal oxide or hydroxide vary from one to five.

20. The composition of Claim 16 wherein the catalytic amount of water is water of adsorption and is supplied to said resin composition by admixture of clay and other inert fillers.

21. A hard, solvent resistant resin comprising the product of polymerization of the composition of Claim 16.

22. A thermosetting resin composition which comprises in admixture (a) up to 75 percent by weight of an inert filler, (b) at least 25 percent by weight of a resin consisting essentially of the composition of Claim 1, and including (c) a catalytic amount of a free radical catalyst.

23. The composition of Claim 22 wherein the filler is glass fiber.

24. A method for preparing a thermosetting resin composition according to any one of Claims 1 to 15 which comprises (A) reacting a polyepoxide with an ethylenically unsaturated monocarboxylic acid in the proportions of 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid, (B) further reacting the secondary hydroxy1 groups formed by the epoxide-carboxylic acid reaction with a dicarboxylic acid anhydride to provide pendant half ester groups, and (C) blending the resin with up to 70 percent by weight of the combined weight of a polymerizable monomer containing a C=CH2 group.

25. A method of producing a thermosetting resin composition according to any one of Claims 16 to 23 which comprises mixing at least 0.75 equivalents of a metal oxide or hydroxide, where the metal is selected from Group II of the periodic chart, per equivalent of carboxylic acid (-C00H) and at least 0.25 equivalents of water per equivalent of carboxylic acid (-C00H) to a vinyl ester resin containing free carboxylic acid groups, said resin prepared by blending up to 70 parts of a polymerizable monomer containing a group with at least 30 parts of a polymerizable synthetic resin prepared (a) by reacting an ethylenically unsaturated monocarboxylic acid with a polyepoxide, and then (b) reacting a dicarboxylic acid anhydride with the secondary hydroxyl groups formed from the epoxide-carboxylic acid reaction to provide pendant half ester groups; said reactants combined in the proportion of 0.8 to 1.2 equivalents of epoxide per equivalent of carboxylic acid and 0.1 to 1.2 moles of dicarboxylic acid anhydride per equivalent of epoxide .

26. The method of Claim 25 wherein the metal is magnesium, calcium or zinc.

27. The method of Claim 25 wherein the water is water adsorption and is supplied to said resin composition by admixture of clay and other inert fillers. THIS 29th P.O.bUX. llo9, tib-AVlV Attorneys for Applicants