CA1125943A - Curable resinous compositions - Google Patents

Abstract

Abstract of the Disclosure Curable resinous compositions comprising alumina trihydrate, a compound containing at least two polymerizable vinyl groups per molecule, a polydiene polymer and optionally a polymerizable monovinyl compound are disclosed. The compositions are useful in molding and laminating applications.

Description

CURABLE RESINOUS COMPOSITIONS

Background of the Invention The present invention relates to curable resinous compositions~, to the cured products prepared therefrom and to method for preparing such cured products. More particularly, this invention relates to curable compositions containing~alumina trihydrate which can be molded or laminated to form cured products whicb have a high degree of fire retardancy.
~; Curable resinous compositions containing alum na trihydrate are disclosed in U.S. Patent 4,041,008 to Makhlouf and Parker. The resinous ::
component of these compositions is an unsaturated polyester resin which is formed from condensing alpha, beta-ethylenically unsaturated dicarboxylic acids such as maIeic acid with polyols such as ethylene and propylene glycol. The polycondensate is thinned with a vinyl monomer such as methyl methacrylate to form the resin. When these compositions are cured9 they produce excellent fire-retardant articles. However, the degree of fire retardancy attained is limited by viscosity increases as the alumina trihydrate is added. High resin viscosities are undesirable because they have poor handLing characteristics for molding and laminating.
Increasing the vinyl monomer content to counteract the viscosity increase with added alumina trihydrate results in cured products with unsatisfactory properties.
The present invention overcomes these shortcomings in the prior art and provides resinous compositions with relatively high levels of alumina trihydrate. In the present invention, the resinous components of the compositions are of much lower viscosity than the resinous components ~Z59~ ~

., of U.S. 4,041,008 and can accept higher levels of alu~ina trihydrat~ ~
~esulting in better fire-r2tardant prDperties without unacceptable viscosity increases.

,;, . Summary of the Invention - :
In accordance ~th the present invention, a surable co~position suitable for ~olding ~nd la~inating i~ di~closed. The compo~itio~ comp~i3es:
(A) 1~ to 95 percent of 8 co~pound containing st least two : .
polymerizabl~ ~;nyL groups per ~oIecule; : ! .
. (B) l to 50 percsnC oE 8 poIydiene polymer; ; .

10(C) O to 70 percent of a polymerizable mono~inyl co~pound; ~ -the perceneag~ by weight of ~A), tB) and (C) bei~g based on the totsl weigbt of ~A), (B) and (C); and , ~ :
(D) st lea.~t S0 percent by weight of alumina trihydrate, the percentage by weight being based on total weight o~ (A)) (B), SC) and ~5~D). t-Mor~ particularly, there i8 provided a curable molding or laminating compositlo~ comprlsing:
~A) 17 to 95 percent by weight of a compound containing a~ least tw~ .
polymerizable ~inyl group~ and fro~ 2 to 5 ester groups per mole-2D . cule;
(B~ from 1 to 50 percent by weight of a polydienQ poly~er;;
~C) 0 to 70 percent by weight of ~ poly~erizable monovinyl compound; ~ !
the percentage by wel~ht o~ ~A), ~B) and ~C) being based on total weight o~
~A), (B) and ~C); (A), ~B~ ~nd tC) when ~lxed together fonm a Iow viscosi~y :
~Olueion havi~g a vi9c09ity less tha~ 3.0 poises a~ 30C, and (D3 at least 50 percent by weight o~ alumina trihydrate, the percentage . by uelght being based on total weight of ~A), ~B), (C) snd (D);
said compositlon bein& of su~ficlent viscoslty for molding or ~aminating under pressure and capable of being cured by heatin8 under pressure in the presence o~ a Sree radical additio~ poly~erlzatlon initiator at a tempe~ture o~ 250- .
350 F. gl21~177 C.~ for about 30 ~econds to 30 minutes. J

~L2~
~h~ ~nventioa ~180 proYide8 8 ~et~od for preparing cured res{nou~
article~ from the above-described compo6ition in ~hort curing cycle~, i.e., 30 seconds to 8 minutes, and provides the cured articles ihe~sel~es~ The cured articles have excellent appearance being s~ooth 3nd glosæy ant bav~
excellent fire-retardant properties, i.e., low ~lame ~pread~, lo~ smoke densitie~ ~ad high oxygen indices.
, ~,", . ' ~ ',., . ' ~
Brief Description of the Prior Art Besides U~S. Patent 4,041,008 mentioned above~ other prior ~rt wbich may be c3nsidered pertinent to the presèn~ invention 1~ as fot.lows:

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U.S. Patent 2,688,009 3,313,545 3,438,933 3,502,338 3,912,773 Japanese Patent Application 71.63766 (Kokai 73.29~32) Japanese Patent ~pplication 16155/72 (Kokai 96640/73) U.S. Patent 2,688,009 discloses a mixture of a liquid poly-butadiene polymer in combination with at least 5 percent by weight of a divinyl compound such as divinyl benzene. The mixtures can be combined with a free radical catalyst and polymerized to form a product at a temper-ature of about 70 to 250F. There is no disclosure in the patent of compositions containing alumina trihydrate.
U.S. Patents 3,313,545; 3,438,933 and 3,502,338 disclose molded golf balls made from a polybutadiene elastomer and a crosslinking monomer such as butylene glycol dimethacrylate or trimethylolpropane trimethacrylate.
The compositions can be combined with fillers such as silica and glass and also aluminum oxide can be incorporated into the compositions. However, there is no disclosure in the reference of compositions containing alumina trihydrate.
U.S. Patent 3,912,773 discloses resinous compositions which are suitable for casting comprising a mixture of vinyl monomers and a thermo-plastic polymer. The compositions are disclosed as capable of being Eilled with alumina trihydrate. The use of polydiene polymers is not disclosed.
Japanese Patent Application 71.63766 (Xokai 73.29832) discloses thermosetting resinous compositions which are workable liquid compositions suitable for casting and are curable in the presence of organic peroxides.
The compositions comprise the following:

~259~3 :

(A) 100 parts by weight of 1,2-polybutadiene having a molecular weight of about 500 to 5000;
~B) 10 to 80 parts by weight of an acrylic or methacrylic acid ester such as methyl methacrylate; and ~C) 10 to 60 parts by weight of a multifunctional acrylic or methacrylic ester such as ethylene glycol dimethacrylate or trimethylol-propane trimethacrylate.
There is no disclosure in the reference of alumina trihydrate-; containing compositions. ~ ~
Japanese Patent Application 16155/72 ~Kokai 96640/73) discloses compositions comprising:
:
(A) 30 to 70 percent by weight of an alkyI methacrylate such as methyl methacrylate and 70 to 30 percent by weight of styrene or an alkyl fumarate and from 0 to 15 percent by weight (0-13 percent based on total weight of vinyl monomer and polybutadiene~ of a polyvinyl compound such as ethylene glycol dimethacrylate, (B) polybutadiene having a molecular weight of 1000 to .
2000, and (C) alumina trihydrate.
There is no disclosure in the patent of composltions containing greater than 13 percent by weight of the polyvinyl compound. Compositions with low amounts of polyvinyl compound require exceedingly long curing times. For example, the compositions of this particular Japanese patent are disclosed as being molded for a period of about 1 to 10 hours.
Although the prior art discloses many of the ingreclients used in thP compositions of the present invention, there is no suggestion in the prior art of combining the ingredients in the manner of the preFent invention ~s~

to arrive at compositions which cure in short molding cycles to produce products having excellent appearance and fire-retardant properties.

Detailed Description The curable compositions of the present invention are prepared by mixing the compound containing at least two polymerizable viDyl groups per molecule (polyvinyl compound) and the polymerizable monovinyl compound (if used) with the polydiene polymer to form a low viscosity solution. The solution preferably will have a viscosity less than 3.0 and usually within the range of about 0.2 to l.0 poises at 30C. A vinyl polymerization catalyst and optional ingredients such as polymerization accelerators, promoters or inhibitors are then added to the solution with stirring.
Usually only low shear stirring is required. ~ext, the alumina trihydrate and optional ingredients such as mold release agents, fillers and rein-forcements are added with high shear mixing to form the curable compositions.
The poLyvinyl compound is needed to provide crosslinking and short curing cycles. The polyvinyl compound contains at least two vinyl^
groups per molecule which are capable of entering into a vinyl-type polymerization.
These compounds usually have molecular weights less than 500, more often less than 400.
Examples of polyvinyl compounds are esters having 2 to 5, prefer- -ably 2 to 3, ester groups and at least 2, preferably 2 to 3, polymerizable vinyl groups. Included are di, tri, tetra and penta esters of polyhydric alcohols with unsaturated carbo~ylic acids as well as esters of polybasic acids with unsaturated alcohols. The esters are non-volatile liquids at temperatures at which they are mixed and preferably contain from about 6 to 30 carbon atoms, preferably 6 to 22 carbon atoms. Examp~es of esters which ~s~

can be used are those formed from reacting an unsaturated carboxylic acid having 3 to 16 carbon atoms such as acrylic acid, methacrylic acid and ethacrylic acid with a polyhydric alcohol containing from 2 to 16 carbon atoms, preferably 2 to 6 carbon atoms such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, tetramethylolmethane, glycerin, pentaerythritol and 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxy propionate.
It is also possible to use esters which are formed from reacting a polybasic carboxylic acid having from about 4 to 10 carbon atoms such as malonic, maleic, fumaric, itaconic, succinic and adipic with an unsaturated alcohol such as allyl alcohol or methallyl alcohol. Also polyvinyl compounds such as amide acrylate formed from reacting acrylic or methacrylic acid with amide alcohols, for example, diethanolamine-formic acid reaction products can be used.
The preferred polyvinyl compounds are esters of acrylic acid or ~ethacrylic acid with polyhydric alcohols such as ethylene glycol and trimethylolpropane.
The polyvinyl compound should constitute from about 17 to 95 and preferably from about 25 to 60 percent by weight of the resinous component.
Amounts less than 17 percent by weight are undesirable because the composi-tions do not cure sufficiently in short curing times which are commercially desirable and may result in articles with insufficient structural strength.
Amounts greater than 95 percent are undesirable because of brittleness and poor appearance of the cured articles.
The polydiene polyme~ contributes surface smoothness and flexi-bility in the cured articles. Somewhat surprisingly, the polydiene also s~

provides fire-retardant properties. It has been found that compositions without polydiene or substituting other polymers such as polyesters or polyethers for the polydiene result in cured articles with higher flame spreads.
The polydiene polymers include polymers of 1,3-dienes containing from 4 to 12 and preferably from 4 to 6 carbon atoms. Typical dienes include 1,3-butadiene which is preferred, 2,3-dimethyl-1,3-butadiene, isoprene and piperylene. Also, copolymers o~ 1,3-butad;ene and a monomer copolymerizable with 1,3-butadiene such as isoprene and piperylene can be used. Other polymerizable monomers such as methyl m~thacrylate, acrylic acid, styrene and acrylonitrile can also be used, but their use is not preferred.
As mentioned above, the preferred polydiene polymers are homo-polymers of 1,3-butadiene. The polybutadienes can contain predominantly lS 1,2- (vinyL) unsaturation but polybutadienes containing predominantly (that is, greater than 50 and preferably greater than 60 percent) 1,4- unsatura-tion are preEerred. Useful polybutadienes contain from about 10 to 30 percent cis 1,4- unsaturation, 40-70 percent trans 1,4- unsaturation and 10-35 percent 1,2- vinyl unsaturation.
The polydiene polymers can be alkyl terminated or terminated with acid groups, hydroxyl groups or with ethylenically unsaturated acryloxy groups such as generally descrihed in U.S. Patent 3,652,520 to Ryan et al.
Polydiene polymers terminated with hydroxyl groups are preferred because of compatibility with the other ingredients in the composition.
The polydiene polymers of the present invention are normally liquids at room temperature and preferably have number average molecular weights within the range of about 500 to 15,000j more preferably 1000 to ~:~L2~gL3 5000. Polydienes having a molecular weight less than 500 are not preferred because unsatisfactory physical properties in the cured products result, whereas polydienes having a molecular weight greater than 15,000 are not preferred because of high viscosities.
The polydiene polymers should constitute from about 1 to 50, preferably from about 5 to 20 percent by weight of the resinous components.
Amounts less than 1 percent by weight are undesirable because of relative brittleness in the cured articles and relatively high flame spreads.
Amounts greater than about 50 percent are undesirable because the composi-tione cure with difficulty, may have poor structural strength and high viscosities.
Optionally, the composition can contain up to 70 percent by weight of a polymerizable monovinyl compound such as an alkyl acrylate or an alkyl methacrylate containing up to 6 carbon atoms in the alkyl group.
lS Examples include methyl methacrylate, which is preferred, ethyl acrylate, isobutyl acrylate and hexyl methacrylate. Hydroxy-substituted alkyl acrylates or methacrylates can also be employed. F,xamples include hydroxy-ethyl acrylate and hydroxypropyl methacrylate. Examples of other vinyl monomers are vinyl acetate and vinyl propionate. Use of the monovinyl compound in amounts greater than 70 percent by weight is not recommended because of insufficient cure in short curing cycles.
Preferably, the resinous component of the present invention contains less than 10 percent by weight aromatic ingredients such as divinyl benzene, styrene or the like; the percentage by weight being based on total weight of resinous ingredients, i.e., polyvinyl co~pound, poLydiene and monovinyl compound. More preferably, the resinous component will contain less than S percent hy weight aromatic ingredients and most preferably ~S~3 will be free of added aromatic ingredients other than free radical initiators, accelerators, inhibitors~ mold release agent or other non-reactive ingredients.
Also present in ehe composition is alumina trihydrate. Alumina trihydrate imparts fire-retardant properties such as low flame spread and high oxygen indices as will be described below. The alumina trihydrate should constitute at least 50, preferably from about 55 to 85 percent by weight of the curable composition based on total weight of the resinous component and the alumina trihydrate. Amounts less than 50 percent by weight, although contributing desirable properties, do not provide for optimum fire retardance. Amounts higher than 90 percent by weight are undesirable because of high viscosities.
Besides alumina trihydrate~ other fillers or pigments may be included in the resin formulation, although the total filler (including alumina trihydrate) content should not exceed 90 percent by weight based on total weight of filLer and resin because of viscosity considerations.
Examples of other fillers include calcium carbonate, magnesium sulfate, magnesium carbonate and potassium aluminum sulfate, diatomaceous earth and clay. Examples of pigments are TiO2, transparent iron oxide and phthalocy-anine pigments.
The compositions of the present invention are cured through vinyl addition polymerization. This polymerization is free radical initiated and suitable free radical addition polymeri~ation initiators incLude benzoyl peroxide, tertiary-butyl perbenzoate~ tertiary-butyl peroctoate, tertiary~
butyl hydroperoxide, cumene hydroperoxide, azobis(isobutyronitrile), methyl ethyl ketone peroxide, and the like. Catalyst is generally used in amounts of about 0.1 to 2 percent by weight based on total weight of the resinous ingredients, the amounts varying with the activity and amount of any accelerator and inhibitor which may be used in the resinous system.

~25~

Examples of accelerators which are used to reduce the curing temperature include cobalt salts such as cobalt octoate or cobalt naphthenate.
The amount of accelerator used can vary widely but is usually within the range of 0.1 to l percent by weight based on total weight of the resinous ingredients.
To prevent any tendency for premature gelation, a gelation inhibitor may be incorporated into the resin system. Suitable inhibitors are selected from the quinone and phenolic compounds and include para-benzoquinone, hydroquinone and 4-tert-butyl catechol. The amount of inhibitor required in the mixture can be varied widely but preferably is in the range of 0.001 to about O.l percent by weight based cn weight of the resinous ingredien e s .
The compositions of the present invention are usually reinforced with glass fibers or other common reinforcements such as steel wire, boron fibers, wood and vegetable fibers. However, because of strength and cost considerations, fiber glass reinforcement is preferred. Fiber glass for reinforcement is well known in the art and the detailed description of various types of glass fibers is not considered a necessary part of the detailed description of the present invention. If such a detailed descrip-tion is desired, reference is made to Reinforced Plastics, Theory and Procedure, by M. W. Gaylord, copyrighted 1969 by Koppers Co., Inc., pages 47-72.
In general, where the compositions of the present invention are reinforced witil glass, abollt 5 to 70 percent by weight glass fibers, based on total weight of the curable composition including glass should be used.
Besides the ingredients mentioned above, other materials may be added to the composition. Examples include mold release agents such as ~2~

zinc stearate or ultraviolet light stabilizers such as o-hydroxyphenyl ketones and 2-(2-hydroxyphenyl)benzotriazoles. The amounts of these other additional components are ~uite small and do not generally in combination exceed about 3 percent by weight of the total weight of the curable composition.The compositions of the present invention are cured at an elevated temperature of about 250 to 350F. (121 to 177C.) for a time as short as 30 seconds to 30 minutes, typically 30 seconds to 8 minutes, or more, depending on the curing process, the resin system, the thickness, size and shape of the item being produced.
Curable compositions described herein may be used in premixed, preformed or mat molding applications and laminating as well known in the art.
In the case of premix molding, the resinous component is intimately mixed with the alumina trihydrate and usually chopped glass fibers and other ingredients such as mold release agent and polymerization initiators in a high shear ~ixing apparatus such as a Sigma blade mixer. The resulting dough-like mass is easily handled and is charged in weighed quantities to a matched metal die mold maintained at an elevated temperature, 250 to 350F.
(121 to 177C.) and pressure applied (50 to 1000 psi) for a period of 30 seconds to 15 minutes to cure the resin to form a rigid article which is ejected hot from the mold.
In preform or mat molding, the curable composition which contains the resin, alumina trihydrate, moLd release agents and polymerization initiators is poured over preformed chopped glass strand mat or continuous strand glass mat and placed in a matched metal die mold where a flow of the resin mixture is accomplished and a curing reaction effected under the conditions of temperature and pressure mentioned above.

In laminating, the curable composition containing resin, alumina trihydrate, mold release agent and polymerization initiators is brought together with glass reinforcement to form a composite layer between two plastic covering sheets to form a laminate. The lay-up thickness and resin content is controlled by exerting pressure on the squeeze rolls through which the laminate passes. The laminate is then drawn through a heating zone by a suitable pulling mechanism. Cures are generally at elevated temperatures, that is, from about 120 to 250F. ~49 to 121C.), and the ; time of cure will usually be for about 30 seconds to 20 minutes.
As mentioned above, the curable compositions of the present invention have excellent fire-retardant properties. The test procedures which are used to measure fire retardance are the Underwriters' Tunnel Test (ASTM E-84) and a laboratory scale test referred to as the Monsanto Tunnel Test, the oxygen index and the smoke density.
The Underwriters' Tunnel Test and the Monsanto Tunnel Test measure the flame spread characteristics of cured compositions of the present invention. According to the ASTM manual, the Underwriters' Tunnel Test evaluates burning characteristics and is applicable to any type of material. The purpose of the test is to determine the comparative burning characteristics of the material under test by evaluating the flame spread over its surface. The test chamber is a horizontal duct, 17-l/2 inches wide, 12-1/2 inches high, 25 feet long. Red oak is the calibration standard and is arbitrarily assigned the value of 100. A value of O is assigned to asbestos. Other materials are reported proportionately.
It has been suggested that the following classifications be assigned to the various flame spread ratings:

~25~

Flame Spread Classific _ion 0-25 Class A, non-combustible 25-75 Class B, fire-retardant 75 and up Class C, co~bustible The Underwriters' Tunnel Test is a good measure of flame spread, however, the test is expensive to set up and to conduct.
There is a iaboratory scale test which gives an indication of flame spread. The laboratory scale test is referred to as the Monsanto Tunnel Test and is described in JOURNAL OF PAINT TEC~NO~OGY, 39, (511), 494 (August 1967). In a Monsanto Tunnel Test, a sample 2 feet by 3-3/4 inches is slanted at an angle of about 45 degrees Erom the horizontal. A specified heat source is burned at the bottom of the sample and the sample is then - burned for four minutes. The flame spread or how far the flame spreads up the sample is reported. The cured composltions of the present invention have Class A flame spread ratings as determined by the Monsanto Tunnel Test.
The oxygen index is determined according to ASTM D~2863. In general terms, the oxygen index of a material is the percentage by volume of oxygen in the atmosphere necessary to support combustion of the material.
For example, air contains 21 percent by volume oxygen. If a material burned in air, i~ would have an oxygen index of 21 or lower. The higher the oxygen index of the material, the harder it is to get the sample to burn. Thus, the oxygen index is a measure of the fire retardance of the sample. Cured resinous materials of the invention containing hydrated alumina have oxygen indices of at least 50, preferably at least 70, which is easily obtainable when the resin contains from about 50 to 90 percent by weight alumina trihydrate.

~2~

The amount of smoke generated by burning cured compositions of the invention can be determined by measuring the smoke density according to a modified version of ASTM D-2843. Briefly, the testing procedure involves inserting a cured specimen of accurate, predetermined dimensions inside a ~BS Aminco smoke chamber. The chamber is substantially airtight and contains a photocell in the ce;ling and a standardi7ed light source in the floor which cooperate with one another to measure the optical transmittance through the height of the chamber. The specimen is then exposed to an open flame and burned ar, in another aspect of the test, the specimen can be subjected to a source of radiant heat and permitted to smolder. In both aspects of the test, the samples are subJected to combustion and the smoke that is generated is collected in the chamber during the course of the test which usually lasts about 20 minutes, the optical transmission is constantly recorded and the minimum value is taken as the measure of the smoke density.
The smoke density is a logarithmic function of the optical transmission as is shown by the following table:

Maximum Smoke Density (D~) Conversion of Percent Transmittance to Smoke Density Percent Transmittance Dm 17.5 lO0 3,0 201 0.52 301 0 090 40l 0.016 - 501 0.0028 60l 0.00049 701 ~ ~;9~

Cured compositions of the present invention ~hen burned as described above havP smoke densities of about 200 or less, preferably 150 or le~s.

xamples I and II
The following two examples are preferred embodiments of the invention. The examples sho~ curable compositions prepared from the following mixture of ingredients:

Parts by We~ght (Percent_by Wei~h~) Ingredients Example I

A - ethylene glycol dimethacrylate 57.5 (57.5)4 B - trimethylolpropane dimethacrylate - 32 (32) C - hydroxypropyl methacrylate 5.4 (5.4)4 6 (6) D - methyl methacrylate 23.2 (23.2)4 47 (47) E - hydroxy-terminated polybutadienel 13.9 (13.9)4 15 ~15) 1~ F - alu~ina trihydrate 3503 (77.8)5 350 (77.8) G - zinc stearate (mold release agent) 5.0 5.0 H - tertiary-butyl perben%oate tfree radical initiator) 0.67 0.67 2Q I - tertiary-butyl peroctoate 0.67 0.67 (free radîcal initiator) J - glass mat2 152.0 t25)6 152.0 (25) lCommercially available from Arco Polymers Inc. as R45-HT*having a number average molecular weight of 2800.

2~ ZTwo plie.s of M-8600 glass mat, 2 ounce, comrnercially available from Owens Corning Fiberglas Corporation.
380 percent by weight alumina trihydra~e having a particle size of

3-10 microns com~nercially available from Alcoa Company as G331, 20 percent by weight of alumina trihydrate having a particle gize less than 3 microns * Trade M~rk ~ 15 -~ 9.~3 ~

*
commercially available from Alcoa s,ompany as H710; the pe~centage by weight based on total weight of alumina trihydrate.
4Baaed on total weight of (A), (B), (C), (D) and (E).
5Based on total weight of (A), (B), (C), (D)~ (E) snd ~F).
g 6Based on total weight of tA)~ (B), (C), ~D), (E), (F), (G), (H), (I) and tJ).
In the above examples, the polybutadiene was dissolved with ~
stirring in a mixture of the vinyl monomers. The alumina trihydrate and zinc stearat~ were then added with high shear mixing using an a;r motor and 1~ a propeller stirring blade ~ form a unifor~ composition. The~viscosiCies of the composition are reported below. The composition was then poured over the glass mat and charged s~o a chrome plated match metal mold. The compositions were cured at 300-F. (149-C.), 1000 psi for 3 minu es to yield smooth, white, cured areicles having the physical properties ~hown below.
15 ~2L~ r~ xample I Example II
Brookfield viscosity in centipoises, ~o. 7 spindle, 25-C.
2 rpm 380,000 360,000 20 rp~ . 80,000 64,000 20 Monsanto Flame Spread Rating 0 2 Oxygen Index 1001 100 Dm Flaming 121 76 D~ Smoldering 39 61 Barcol Hardness7 40-42 18-30 25 60- Gloss~ 77-80 78-82 Surface Smoothness9 64 66 7Barcol hardness 15 determined with a 934 Impressor. It i8 a com-parable measure of hardness using a scale of values of 0 to 100. rne higher the ns~mber, the harder the material.

* Trade Ma~k Jzs~

3Gloss determined with a 60- gloss meter manufactured by Hunter Labs, Model No. D48D.
9Tbe surface s~oothness i8 de~ermined by ~raversing the surface of the molded article with a proilometer (Surfanalyzer*150) manufactured by Clevite Company, Division of Gould Industries, which measures the roughness of the surface. Surface roughness is expressed as microinches of waviness in a 2-inch scan. The g~eater the numerical value, the rougher the surface.
Sample did not support its own combustion at 100 pescent oxygen.
Example I i9 preferred becauee of its excellent fire-retardant properties tO flame spread rating). Example II is preferred because of its excellent fire-retardant properties; its low viscosity and good handling characteristics.

Examples III and IV
The following two examples show curable compositions with low L5 amounts of monovinyl monomer a~d with no vinyl monomer. The compositions ~
were prepared from the Eollowing ingredients:
Parts by Weight (Percent by Weight) Ingredients Example III Example IV
ethylene glycol dimethacrylate267.1 (80.7) 285 (86.1) 20 hydroxypropyl methacrylate 17.9 (5.4) _ _ hydroxy-ter~inated polybutadiene of Examples I and II 46 (13.9) 46 ~13.9 alumina trihydrate of Examples I and II 993 (75) 993 (75) æinc atearate 16.7 16.7 as tertiary-butyl perbenzoate 2.2 2.2 tertiary-butyl peroctoate 2.2 2.2 glass mat of Examples I and II441 (25) 441 (25) * Trade Mark 59~3 The compositions were prepared, processed and molded as generally described in Examples I and II to yield smooth, glossy panels having Monsanto Flame Spread Ratings of 5.4 and 10.7, respectively.

Examples V -:VIII
A series of experlments similar to that of Example II were : prepared but with decreasing amounts of ~ trimethylolpropa~e trimethacrylate and correspondingly increasing amounts of methyl methacrylate. The curable compositlons were prep~red from the following ingredients:
Parts by Weight (Percent by Weight) ~10 Ingredients Example VExample VI Example VIIExample VIII
: trimethylolpropane trimethacrylate89.4 (27)72.8 (22)56.3 (17) 39.7 (12) ~ hydroxypropyl : : - methacrylate 19.9 (6) 19.9 (6) l9.9 (6) 19.9 (6) : ~ :
methyl mPthacrylate 172.1 (52) 188.7 (57) 205.2 (62) 221.8 (67) ~hydroxy-terminated ~: : polybutadiene of Examples I and XI 49.7 (15) 49.7 (15) 49.7 (15) 49.7 (15) tertiary-butyl ;~ 20 perbenzoate 2.2 2.2 2.Z 2.2 tertiary-butyl peroctoate 2.Z 2.2 i 2.2 2.2 alumina trihydrate of Examples I and II 993.0 (75)993.0 (75) 993.0 (75) 993.0 (75) zinc stearate 15.7 15.7 15.7 15.7 glass mat of Examples I and II441 (25)441 (25) 441 (25) 441 (25) The curable compositions were prepared, processed and molded as generally described irl Examples I and II to yield panels having the following properties: ~

- , . .

Property Example V Example VI Example VII Example VIII
Barcol Hardness 22 20 10-15 10 60~ Gloss 78-82 73-79 55-60 30-40 Surface Smoothness 45 39 42 1,275 The Examples show that decreasing the amount of polyvinyl compound while correspondingly increasing the amount of monovinyl compound results in loss of hardness, gloss and surface smoothness which is believed to be due to insufficient cure. At below 17 percent by weight trimethylolpropane trimethacrylate, extremely rough panels are obtained. When Example VII was repeated with a longer molding cycle, i.e., 300C., for lO minutes, a harder panel having a Barcol ~lardness of 30 was obtained.

E~amples IX - XIII
The following examples are of curable compositions with various polybotadienes. The compositions were prepared from the following mixtures 15 ~ of mgredlents :

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The curable compositions were prepared, processed and molded as generally described in Examples I and II to yield smooth, glossy panels having the following Monsanto Flame Spread Ratings:
Example IX Example X Example XI Example XII Example XIII
510.7 16.1 5.4 10.7 16.1 -Examples XIV - XVI
The following examples are curable compositions with varylng amounts of polybutadiene. Examples XIV and XV were prepared from the I following mlxtures of ingredlenes:
Parts by Weight (Percent by Weight) Ingredient Example XIV Example XV
trimethylolpropane trimethacrylate 105.9 (32) 314.5 (95) ; hydroxypropyl methacrylate 19.9 (6) hydroxy-terminated polybutadiene g ~ of Examples I and II 66.2 (20) 16.6 (5) methyl methacrylate 139 (42) eertiary-butyl perbenzoate 2.2 2.2 tertiary-butyl peroctoate 2.2 2.2 zinc stearate 19.9 19.9 alumina trihydrate of Examples I~and II 993.0 (75) 993.0 (75) glass mat of Examples I and II441 (25) 441.0 (25) The compositions were prepared, processed and molded as generally described in Examples I and II to give smooth, glossy panels.
Example XVI was prepared from the following mixture of ingred~ents:

- Zl : ~ .

9~3 Ingredients Parts by Weight (Perce~t by Weight) trimethylolpropane trimethacrylate 376 (47) hydroxypropyl methacrylate 48 (6) hydroxy-terminated polybutadiene of Examples I and II 120 (15) methyl methacrylate 56 (7) carboxyl-terminaced polybutadienel200 ~25) tertiary-butyl perbenzoate 5.3 tertiary-butyl peroctoate 5.3 lHydroxy-terminated polybutadiene of ~xample I in which the hydroxyl groups were capped with maleic anhydride.

Th~ee hundred forty-five ~345) parts by weight of the mixture of ingredients prepared above were combined with 800 parts by weight of alum1na trihydrate (50/50 aeight mixture of C331 and H710 as described in Examples I and II), 12 parts by weight of z~nc stearate and 200 parts by weight of 1/4 inch chopped strand fiber glass. The ingredients were mixed in a Baker-Perkins mixer to form a homogeneous composition which was then charged to a compression mold and molded at 300F. (149C.) for 3 minutes at 1000 psi. The mold mg had a tensile strength of 3040 psi, a tensile modulus of 0.616 x 106 psi and a percent elongation of 0.67 as determined according to ASTM D-638; a flexural strength of 6410 psi and a flexural modulus of 0.534 x 106 psi as determined by ASTM D-790; a notched izod impact of 4.80 foot-pounds per inch as determined accord;ng to ASTM D-256.

Comparative Examples XVII - XIX
The following examples show the effect of too much monovinyl monomer. The composition was made from the following mix~ure of ingredients:

3~

Parts by Weight (Percent by Weight) Ingredients Example XVII Example XVIII Example XIX
trimethylolpropane trimethacrylate - 56.3 (17) 66.2 (20) ethylene glycol dimethacrylate 9 (9) hydroxypropyl methacrylate 5.4 (5.4) 82.8 (25) 248.3 (75) -hydroxy-terminated polybutadiene of Examples I and II 13.9 (13.9) 26.5 (8) 16.6 (5) methyl methacrylate 71.7 (71.7) 165.5 (50) tertiary-butyl perbenzoate 0.67 2.2 2.2 tertiary-butyl peroctoate 0.67 2.2 2.2 ; ~ zinc stearate 5 l9.9 l9.9 alumina trihydrate of Examples I
and II 300 (75)993 (75) 827.5 (71) glass mat of Examples I and II 133 (25) 317 (25) 290 (25) 15~ When the compositions were prepared, processed and molded as described in F.xamples I and IIj panels were obtained which were cracked, pitted and blistered, having low gloss and glass fiber pattern.

Comparativè Example XX
The following example shows a composition prepared without an elastomer. The composition was prepared from the following mixture of ingredients:
Ingredients Parts by Weight (Percent by Weight) ethyLene glycol dimethacrylate66.8 (66.8) methyl methacrylate 26.9 (26.9) hydroxypropyl methacrylate 6.3 (6.3) aluMina trihydrate o~ Examples I and II 300 (75) zinc stearate 5 tertiary-butyl perbenzoate 0.67 tertiary-butyl peroctoate 0.67 glass mat of Examples I and II133 (25) 5~

When the compo~ition was prepared, proce3~ed and molded as described in Examples I and II, a brittle panel with ma~sive surface cracking in the center resulted. The panel had a Honsanto ~lame Spread Rating o f 42. 8.

S Comparative Examples XXI ~
The following examples show the effects of replacing a polydiene elastomer with oxygen-containing polymers. The compositions were prepared fro~ the following mixtures of ingredients:

Parts by Weight (Percent by Weight~
Ingredients Example XXI Example XXII Example XXIII
ethyiene glycol dimethacrylate S7.5 (57.5) 57.5 ~57.5~ 57.5 (57.5) methyl methacrylate 23.2 (23.2) 23.2 (23.2) 23.2 (23.2) hydroxypropyl methacrylate 5.4 (5.4) 5.4 (5.4) 5.4 ~5.4~
oxygen-containing elastomer 13.91(13.9) l3.92(13.9) 13.93(13.9) alumina trihydrate of Examples I and II 300 (75) 300 (75) 300 (75) zinc stearate 5 5 5 tertiary~butyl perbenzoate 0.67 0.67 0.67 tertiary-buCyl peroctoate 0.67 0.67 0.67 glas~ mat of Examples I and II 133 125~ 133 (25) 133 (25) lLow molecular weight unsaturated polyester formed from conden~ing maleic anhydride, adipic acid, propylene glycol and ethylene glycol in a molar ratio of 3/7/3/9 to an acid number of 22.8 and a Gardner-Holdt vi~cosity of G as a 75 percent solution in 2-ethoxyethanol.

22000 molecular weight polypropylene glycol commercially available from Wyandotte Chem;cal Company as PPG~2010.
37000 molecular weight polycaproLactone diol commercially available from Union Carbide Corporation as PCL-300.

* Trade Mark ~'' .

l~S9~3 When the compositions were prepared, processed and molded as generally described In Example II, smoothj glossy panels resulted which had the followlng Monsanto Flame Spread Ratings:
Example XXI ExampLe XXII Example XXIII
-32.1 64.2 42.8 As can be~seen, these Monsanto Plame Spread Ratings are much higher than the co~positions of the present inventi~n.

:

-~ .
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Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A curable molding or laminating composition comprising:
(A) 17 to 95 percent by weight of a compound containing at least two polymerizable vinyl groups and from 2 to 5 ester groups per mole-cule;
(B) from 1 to 50 percent by weight of a polydiene polymer;
(C) 0 to 70 percent by weight of a polymerizable monovinyl compound;
the percentage by weight of (A), (B) and (C) being based on total weight of (A), (B) and (C); (A), (B) and (C) when mixed together form a low viscosity solution having a viscosity less than 3.0 poises at 30°C; and (D) at least 50 percent by weight of alumina trihydrate, the percentage by weight being based on total weight of (A), (B), (C) and (D);
said composition being of sufficient viscosity for molding or laminating under pressure and capable of being cured by heating under pressure in the presence of a free radical addition polymerization initiator at a temperature of 250 350°F. (121-177°C.) for about 30 seconds to 30 minutes.

2. The composition of Claim 1 in which (A) is an acrylic or methacrylic ester of a polyhydric alcohol containing from 2 to 5 hydroxyl groups.

3. The composition of Claim 2 in which the polyhydric alcohol contains from 2 to 10 carbon atoms.

4. The composition of Claim 1 in which the polydiene polymer is a polymer of 1,3-butadiene.

5. The composition of Claim 1 in which the polydiene polymer is a hydroxy-terminated polybutadiene.

6. The composition of Claim 1 in which the polydiene polymer has a number average molecular weight of about 500 to 15,000.

7. The composition of Claim 1 in which (C) is a lower alkyl ester of acrylic acid or methacrylic acid containing from 1 to 4 carbon atoms in the alkyl group.

8. The composition of Claim 1 which contains from 55 to 85 percent by weight alumina trihydrate.

9. The composition of Claim 1 which is essentially free of aromatic constituents.

10. The composition of Claim 1 which contains from 5 to 70 percent by weight glass fibers, the percentage by weight being based on total weight of the curable composition including glass.

11. The composition of Claim 1 or 10 in a cured state in the form of a molded or laminated article which has a Class A flame spread rating as determined by the Monsanto Tunnel Test and an oxygen index of at least 50 determined according to ASTM D-2863.

12. A method for preparing a cured resinous molded or laminated article containing alumina trihydrate comprising:
(1) preparing a composition containing:
(A) 17 to 95 percent by weight of a compound containing at least two polymerizable vinyl groups and from 2 to 5 ester groups per molecule;
(B) 1 to 50 percent by weight of a polydiene polymer;
(C) 0 to 70 percent by weight of a polymerizable monovinyl compound;
the percentage by weight of (A), (B) and (C) being based on total weight of (A), (B) and (C); and (D) at least 50 percent by weight of alumina trihydrate, the percentage by weight being based on total weight of (A), (B), (C) and (D);
(2) heating said composition under pressure in the presence of a free radical addition polymerization initiator at a temperature of about 250 to 350°F. (121 to 177°C.) for about 30 seconds to 8 minutes fol-lowed by;
(3) cooling said composition.

13. The method of Claim 12 in which composition (1) is combined with glass fibers before the heating step.

14. The method of Claims 12 or 13 in which the heating step is conducted in a mold at a pressure of about 50 to 1000 psi.

15. The composition of Claim 1 in which the polydiene polymer contains greater than 60 percent 1,4-unsaturation.