CA1046692A - Polyurethane-isocyanurates from novolak resins, polyols and isocyanates - Google Patents

Abstract

POLYURETHANE-ISOCYANURATES FROM
NOVOLAK RESINS, POLYOLS, AND ISOCYANATES
ABSTRACT OF THE DISCLOSURE
Polyurethane-isocyanurates which can be employed in solid elastomeric products, surface coatings, cast or molded objects, or flexible, semi-flexible, semi-rigid or rigid foams are produced from a novolak resin, a polyol, an organic polyiso-cyanate, and a catalyst for promoting the production of iso-cyanurate from isocyanate.

S P E C I F I C A T I O N

1.

Description

104~ 9196 The invention relates to polyurethane-iso-cyanurates that are produced from novolak resins, polyols, organic polyisocyanates, and a catalyst for promoting the production of isocyanurate from iso- -cyanate.
It has been proposed to produce polyurethane-- Lsocyanurates by reacting an alkylene oxide condensate of a novolak resin with an organic polyisocyanate in the presence of a catalyst that promotes the formation of isocyanurate from isocyanate. The alkylene oxide-~volak condensates impart a number of useful properties, such as enhanced thermal stability, to these polyurethane-i8 ocyanurates. H~wever, the use of alkylene oxide-novolak condensates incurs additional expenseJ since these condensates must be produced in a separate step.
The present invention provides a means for incorporating novolak resins in polyurethane-isocyanurate compositions without having to produce the alkylene oxide/novolak condensates in a separate step.
The invention provides a thermose~ composition containing both urethane and isocyanurate groups, wherein said composition comprises the reaction product of (a) ~ a novolak, (b) a polyol, (c) a stoichiometric excess of I an organic polyisocyanate, and (d) a catalytically J effective quantity of a catalyst for promoting the ~ -l~ formation of isocyanurate from isocyanate.
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104~2 9196 The novolaks employed in the invention are known compositions that comprise condensation products of a phenol and an aldehyde, preferably formaldehyde.
Novolaks are known to exist as A-stage, B-stage and C-stage resins, with the C-stage resin being highly crosslinked and insoluble and infusible. For the purposes of this invention, the fusible A- and B-stage novolak resins are employed. It is known that novolak resins can be produced using substituted phenols and that other aldehydes can be used instead of or in addition to formaldehyde. All of these are known, as are the methods by which they are produced, and for the purposes of this invention the term novolak includes any of the known resins.
A particularly preferred novolak is a compo-~itlon that can be represented in simplification by the structural formula:

_ _ l ----¦ CH2~

x , wherein J which represents the number of phenol moieties per molecule, is a number having an average value of at least about two to about 10. The preferred compounds are those in which x has an average value . - .. , ~ ~ , . . , . . - . . .
'' ' . .' '. . ' "'' ' , " ~' " ' ' 104~9Z ~196 from about 2.5 to about 8. While, for simplici~y, Formula I depicts the preferred novolak as being composed of divalent units, it is, of course, under-stood that the terminal units are monovalent and that some of the units may be polyvalent, e.g., trivalent.
The second reactant that is employed in the invention is a polyol having at least two alcoholic hydroxyl groups. The polyol, or mixture of two or more polyols, is selected to have a viscosity such that a solution of novolak in the polyol has a vis-cosity which will enable the solution to be conven-iently handled, e.g., pumped or poured, and mixed with the other constituents of the reaction mixture (which are set forth fully hereinafter) at temperatures within the range of Erom about room temperature up to about 80C. Thus, the polyol or polyol mixture is selected 90 that the viscosity of the polyol/novolak i solution will be below about 9800 centipoises at reaction temperature, and preferably below about 3600 centipoises at reaction temperature. As will be readily understood by the ordinary worker in the art, the selection o the particular polyol or polyol mixture to meet these requirements will depend, to an extent, on factors such as proportion of polyol and novolak, precise nature of the reactants, reaction temperature, and the like.

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~o~ z Among the polyols that can be employed in the invention, either singly or in mixtures, are the following:
(a) Polyoxyalkylene polyols including the adducts of alkylene oxides with, for example, water, ethylene glycol, propylene glycol, glycerol, l,2,6-hexanetriol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol, sucrose, alpha-methylglucoside, alpha-hydroxyalkylglucoside, ammonia, triisopropanolamine, ethylenediamine, phosphoric acid, polyphosphoric acids such as tripolyphosphoric acid, and phenol-aniline-formaldehyde ternary condensation products.
The alkylene oxides employed in producing the polyoxy-alkylene polyols normally have from 2 to 4 carbon atoms.
Propylene oxide and mixtures o propylene oxide with ethylene oxide are preferred.
(b) Polyesters of polyhydric alcohols and polycarboxyllc acids sucn as those prepared by the reaction of an excess of ethylene glycol, propylene glycol, or glycerol, with phthalic acid or adipic acld.
(c) Lactone polyols prepared by reacting a lactone such as epsilon-caprolactone or a mixture of epsilon-caprolactone and an alkylene oxide with a poly-functional initiator such as a polyhydric alcohol, an amine, or an amino-alcohol.
(d) Phosphorus-containing derivatives such as tris(dipropylene glycol) phosphite and other phosphites.
(e) The polymer/polyols produced by the in situ polymerization of a vinyl monomer in a polyol, as disclosed in U.S. 3,304,273, U.S. 3,383,351 and U.S. 3,523,093.

5.

~ o4~ ~ 9 2 9196 The foregoing are merely illustrative and represent only a small number of the many polyols known in the art that can be employed in the invention.
As is known in the art, the foregoing types of polyols can have a wide range of viscosities, ranging from about 50 centipoises to very viscous liquids of about 2300 centipoises or more. (Unless otherwise stated, specific viscosities are those exhibited by the polyol at about 25C.) The novolak resins that will be mixed with the polyol, are normally solid at room temperature, and even if they are liquid at moderately elevated temperatures (e.g. J Up to about 50C.), they are still quite viscous. Therefore, when a very viscous polyol is used, at least one additional polyol having a low viscosity should also be employed in the reaction mixture in order to enable the polyol/novolak solution to meet the viscosity requirements set forth above.
The proportions of novolak and polyol that can be employed are not narrowly critical. The pro-portions depend, to an extent, on such factors as thenature of the materials employed. Normally, the pro-portion of novolak employed will be within the range of from about 10 weight per cent to about 60 welght per cent, based on weight of polyol plus novolak.
While proportions outside these ranges may be used -in some cases, when the novolak is employed in pro-portions below 10 per cent, its contribution to the -~0466~2 properties of the thermoset produc~ tends to diminish.
At proportLons above 60 per cent, the viscosi~y of the novolak/polyol mixture tends to become impracticably high.
The novolak resin and the polyol~are reacted with a stoichiometric excess of an organic polyisocyanate.
Any of the known organic polyisocyanates can be used.
Illustrative thereof are the alkylene diisocyanates, such as tetramethylene diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate; cyclo-alkylene diisocyanates, such as cyclohexylene-1,3-diisocyanate, and cyclohexylene-1,4-diisocyanate;
aromatic diisocyanates, such as _-phenylene diiso-cyanate, p-phenylene diisocyanate, polymethylene polyphenyli80cyanate (i.e., the product produced by phosgenation of an aniline-formaldehyde condensation product), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, mixtures of 2,4- and 2,6-tolylene diiso-cyanate, naphthalene-1,4-diisocyanate, diphenylene-4.4'-diisocyanate, bis(4-isocyana~ophenyl)methane ("MDI"), bis(3-methyl-4-isocyanatophenyl)methane and 4,4'-diphenylpropane diisocyanate; aliphatic-aromatic diisocyanates, such as xylylene-1,3-diisocyanate and xylylene-1,4-diisocyanate, the polyisocyanates a8 disclosed in U.S. Patent No. 2,683,730, as well as the polyisocyanates listed in the publication of Siefken,~Annalen, 562, pages 122-135 (1949). Also 7.

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~ 04~69Z 9196 included are 4,4'J4"-tris(isocyanatophenyl)methane,

3,10-diisocyanatotricyclo[5.2.1.02~6]decane, bis(2-isocyanatoethyl) carbonate, and bis(2-isocyanatoethyl) fumarate. Preferred organic polyisocyanates include ~:
the aromatic polyisocyanates such as tolylene diiso-cyanate, MDI, and polymethylene polyphenylisocyanate.
Organic polyisocyanates that have been pre-reacted with a stoichiometric deficiency of ;lll active hydrogen-containing compound can also be employed.
The organic polyisocyanate is employed in the invention in an amount in excess of tha~ required to react with all of the reactive hydrogen-containlng compositions present in the reaction mixture. Such reactive hydrogen-containing compositlons include the novolak resin described hereinabove, the polyoL having at least two alcoholic hydroxyl groups, and reactive blowing agents such as water~ which can be employed if a foam is desired. To illustrate the proportions that are employed, normally the organic poLyisocyanate will be employed in amounts such that there are at least about 1.2, and preferably from about 1.5 to about 5, equivalents of isocyanato group per equivalent of reactive hydrogen.
Also included in the reaction mixture is a~
catalyst for promoting the formation of isocyanurate from is~cyanate. Among the catalysts that can be employed to promote the formation of isocyanurate 8.

1046~2 9196 from isocyanate are the alkali metal mercaptides.
The alkali metal mercaptides can contain a single ~-mercaptide group in the molecule, or they can have larger numbers thereof. The mercaptide can be aliphatic, aromatic, heterocyclic, cycloaliphatic or polymeric in nature.. The nature of the mercaptide compound is not the controlling factor; the presence in the molecule of the -SM group is the iac~or which imparts catalytic activity to the molecule. Thus, in the broadest sense the catalysts can be defined by the formula:

II X(SM)n wherein X is the organic moiety to which the -SM
group is attached, and n i9 a number having a positive value which can be a8 high as six, and even higher in polymeric substances. The organic moiety X can be an unsubstituted or substituted monovalent or poly-valent group. Thus, it can be a monovalent alkyl group of from 1 to 20 carbon atoms, or an alkenyl group of from 2 to 20 carbon atoms, or an aryl or alkaryl or aralkyl group of from 6 to 10 carbon atoms, or a cycloalkyl or cycloalkenyl group of from 5 to 6 carbon atoms, or a heterocyclic group containing ring carbon atoms and nitrogen or sulfur ` or oxygen ring atoms which ring can have 5 or 6 members; or, it can be a polyvalent radical of any ,' 9 ..

.. . , ... ,, ~ .......... . . . ~ ,- ..
. -, . , . ,, - . -~04~;~92 ~

of said groups when there are two or more SM groups :
attached to the X moiety~ It can also be a polymer chain to which the -SM groups are attachedO
Illustrative of suitable alkali metal mercap-tides are sodium n-butylmercaptide, lithium sec-butyl-mercaptide, sodium hexylmercaptide, lithium decyl-mercaptide, lithium dodecylmercaptide, sodium 2-hydroxy-ethylmercaptide, sodium 14-hydroxytetradecylmercaptide, sodium carboxymethylmercaptide, lithium 2-carboxyethyl-mercaptide, lithium 9-carboxynonylmercaptide, lithium

4-hexenylmercaptide, sodium phenylmercaptide, lithium phenylmercaptide, potassium phenylmercaptide, lithium l-naphthylmercaptide, sodium triphenylmethylmercaptide, sodium 4-chlorophenylmercaptide, sodium tolylmercaptide, lithium xylylmercaptide, sodium cyclohexylmercaptide, and 1,3,4-thiadiazole-2,5-di(sodiomercaptide). Also suitable are the alkali metal salts of 2-mercapto-benzothiazole, octane dithiol, and the reaction product of sodium sulfide with oligomers of epichlorohydrin~
Any alkali metal mercaptide having at least one mercaptide group in the molecule can be used, in-cluding the monomercaptides and polymercaptides, pro-vided that there are no substituents in the molecule that will unduly interfere with the reaction of the ~socyanato group and formation of the isocyanurate group. The mercaptides are characterized by the : ':

10.

.Q4~692 presence in the molecule of at least one mercaptide group of the formula -SM, wherein M is an alkali metal atom such as lithium sodium or potassium. The simplest mercaptldes are those containing only one such group.
However, the compounds suitable for use can contain as many as 8iX or more mercapto or mercaptide groups in the molecule. There can also be present in the mercap-tide molecule other substituent groups, such as carboxyl, hydroxyl, halogen, ester linkages, ether linkages, amido linkages, or any other group whlch would not exert a deterring effect on the reaction.
The alkali metal mercaptide catalyst i8 used at a concentration of from about 0.01 to about 10 mole per cent, and preferably from about 0.5 to 5 mole per cent, the percentage being based upon total equivalents of isocyanate employed in the process. Any catalytic amount sufficient to catalyze the reaction can be employed.

.
A solvent for the catalyst can be used and for this purpose a suitable organic solvent can be employed. As examples of useful solvents dimethyl-, ~ , . .. .
formamide, dimethylsulfoxide, sulfolane, diethyleneglycol, di xane, and tetrahydrofuran are illustrative.
` The alkali metal mercaptides are readily pre-pared by known methods, one of which is the reaction of he slkali~metal or the alkali metal hydride with the rganic mercaptan, preferably in solution. The said .~ . ~ , .

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104~6~Z 9196 solution can be used directly in the process of the invention.
In addition to, or in place of, the above-described alkali metal mercaptides, other catalysts can be employed to promote the formation of isocyanurate from isocyanate. Such other catalysts includ~ an organic orthoborate plus an alcoholate or phenolate as disclosed in U.S. Patent No. 3,697,485, and a strong base such as a tertiary amine, which can be used alone, but is preferably used with an epo~ide as disclosed in U.S. Patent No. 3,211,703.
The invention can be employed to produce solid elastomeric products, surface coatings, cast ob~ects, molded objects, fiber-reinforced objects, or flexible, semi-flexible, semi-rigid or rigid foams.
All of these types of products and their specific utilities are well known commercially, and those skilled in the art are familiar with the reactants and techniques necessary to produce a partlcular type of product. Thus, it is known that flexible products are obtained in the absence of highly functional crosslinkers or in the absence of large amounts of polyols and polyisocyanates having functionalities greater than two. It is also known that as the functionality of the reactants is increased the rigidity of the final product increases. In addition, it is known that the inclusion of a foaming agent will 12. ~

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104~ 2 produce a foam while the exclusion of such agent will result in a solid nonfoamed product.
The hydroxyl number of the polyol or polyol mixture plus novolak employed can range from about 20, and lower, to about 1000, and higher, preferably from about 30 to about 800, and more preferably, from about 35 to about 700. The hydroxyl number is defined as t:he number of milligrams of potassium hydroxide required ror the complete neutralization of the hydrolysis product of the fully acetylated derivative prepared~from 1 gram of polyol plus novolak. The hydroxyl number (or "OH") can also be defined by the equation:

OH G 56.1 x 1000 x f m.w.

where: f - average functionality, that i~, the average number of hydroxyl groups per molecule of polyol plus novolak; and m.w. = average molecular weight of the polyol.
The exact materials employed depends upon the end-use of the polyurethane-isocyanurate product. The molecular weight and the hydroxyl number are selected properly to result in flexible, semi-flexible, or rigid products.
~he polyol or polyol mixture plus novolak usually possesses a hydroxyl number of from about 200 to about l~OO when employed in producing rigid products, from , :
about 50 to about 250 for semi-flexlble products, and from about 20 to about 70 or more when employed to produce 1exible products.
13.

iO46~92 9196 When a fo~m is desired, foaming can be accom-plished by employing a minor amount (for example, from about 0.5 to 25 weight percent, based on total weight of the re~ction mixture), of a blowing agent which is vaporized by the exotherm of the isocyanato-reactive hydrogen reaction. Preferred vaporizable blowing agents include halogen-sub8tituted aliphatic hydrocarbons which have boiling points between about -40~C. and 70C., and wh.ch vaporize at or below the temperature of the foaming ma9s, for example, trichloromonofluoromethane, dichloro-difluoromethane, and methylene dichloride. Other useful blowing agents include water and low-boiling hydrocarbons such as butane, pentane, hexane, cyclohexane, and the like.
Other gases or compounds easily volatilized by the exotherm of the isocyanato-reactive hydrogen reaction can be employed. A further class of blowing agents includes the thermally unstab1e compounds which liberate gases upon heating, such as N,N'-dimethyl-N,N'-dinitrosoterephthal-amide.
In addition to the catalyst for promoting the production of isocyanurate, one can also have pre8ent in the reaction mixture any of the known catalysts previously used in the production of polyurethanes. These can comprise, for example, from 0.05 to 1 weight per cent or more of the reaction mixture. Illustrative thereof are:
(a) tertiary amines such as N-methylmorpholine, N-ethylmorpholine, N,N,N',N'-tetramethyl-1,3-butanediamine, 14.

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104~69Z 9196 I,4-diazabicyclo[2.2.2]octane and ~is[2-(N,N-dimethyl-amino)ethyl] ether;
(b) salts of organic acids with a variety of metals such as alkali metals, alkaline earth metals) Al, Sn, Pb, Mn, Co, Ni, and Cu, including, for example, sodium acetate, potassium laurate, calcium hexanoate, stannous acetate, stannous octoate, stannous oleate, lead octoate, and metallic driers such as manganese and cobalt naththenate, and;
(c) organometallic derivatives of tetravalent tin, trivalent and pentavalent As, Sb, and Bi, and metal carbonyls of iron and cobalt.
Small amounts, e.g., about 0.001% to 5.0%
by weight, based on the total reaction mixture, of an emulsifying agent can be employed when producing foams.
Ixamples include polysiloxane-polyoxyalkylene block copolymers having from about 10 to 80 per cent by weight of siloxane polymer and from 90 to 20 per cent by weight of alkylene oxide polymer, such as the block copolymers described in U.S. Patents 2,834,748 and 2,917,480. Another useful class of emulsLfiers i9 the group of "non-hydrolyzable" polysiloxane-polyoxy-alkyl~ne block copolymers. This class of compounds diffèrs from the above-mentioned polysiloxane-polyoxy- --alkylene block copolymers in that the polysiloxane moiety ls bonded to the polyoxyalkylene moiety through direct carbon-to-silicon bonds, rather than through 15.

.

1 046 6~ Z 9196 carbon-to-oxygen-to-silicon bonds. These copolymers generally contain from 5 to 95 weight per cent, and preferably from 5 to 50 weight per cent, of polysiloxane polymer with the remainder being polyoxyalkylene polymer.
The process of the invention can be carried out as a one-stage process, which can be carried out as a one-step reaction wherein all the reactants and catalyst are reacted in one step to produce the thermoset composition. Alternatively, the one-stage process can be carried out as a two-step reaction wherein all or part of the reactants are pre-reacted to form an iso-cyanato-terminated prepolymer, which is then contacted with the catAlyst and any remaining reactants to form ~he thermoset compositions of the reaction.
In another aspect, the process of the invention can be carried out as a two-stage process. The two-sta~e process can be carried out by simultaneously reacting all the reactants and catalyst, but the reaction is interrupted before a thermoset composition is produced. Instead, this 20 first stage of the process produces a normally solid ~ -(i.e., solid at room temperature), fusible composition (such as is often referred to as a "B-stage" material) that is capable of being transformed by the application of heat into a thermoset composition. Alternatively, the two-stage process can be carried out by first pre-reacting all or some of the reactants to produce a prepolymer, followed by contacting the prepolymer with 16.

~, , , : ........ . . :,, . , . , ... . .. : . -.- , ... . .... :.,.. ,. - .. : . ... . -.. . . . . -104~692 9196 the catalyst and any remaining reactants to form an isocyanurate. Again, however, the isocyanurate pro-duction is interrupted prior to the production of a thermoset composition, to produce a B-stage compo-sition tha~ can subsequently be transformed into a thermoset composition by the application of heat.
The examples set forth below illustrate certain aspects of the invention. All parts and percentages are by weight, unless otherwise stated.
In the Examples, the following reactants were employed:
Novolak A - A phenol/formaldehyde novolak having an average of 5 to 6 phenol groups per molecule;
Polyol A - Polypropylene glycol having an average molecular weight of about 1000 and a viscosity at room temperature of 100-130 centipoises;
I Polyol B - Polypropylene glycol having an average molecular weight of about 425 and a viscosity at room temperature of 65-100 centipoises;
Polyol C - The condensation product of epsilon-caprolactone and diethylene glycol, having an average molecular weight of about 530 and a viscosity at 50-60C. of 65-100 centipoises;

17.

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. 9196 :~

1 ~46 6 9 2 Isocyanate A - The reaction product of excess .:.
tolylene diisocyanate (TDI) with a propylene ;~ .
oxide adduct of glycerine having a hydroxyl number of 650, said reaction product having a free isocyanate (NCO) content of 32 weight per cent;
Isocyanate B - Same as A, except that the free NCO content is 30 weight per cent;
Isocyanate C - The reaction product of excess TDI with the propylene oxide adduct of sorbitol having a hydroxyl number of 490, said reaction product having a free NCO
content of 28 1 weight per cent;
Catalyst A - Sodium phenyl mercaptide (NaSC6H5); .
Catalyst B - Disodium mercaptoacetate (NaSCH2COONa); and :
~ Catalyst C - Dibutyltin dilaurate.

¦ EXAMPLES 1-12 ONE-STA OE PRODUCTION OF POLYURETHANE-ISOCYANURATE THERMOSET COMPOSITIONS

¦ Standard Procedure - The novolak was mixed I in the polyol, and the mixture was then heated in a circulating air oven to a temperature of 40-70C., the catalyst was added to the novolak/polyol solution, and the isocyanate was then added with rapid stirring, to give l~ a homogeneous reaction mixture. Molded thermoset plaques ¦~ about 20 mils thick were then produced by pouring the reac-tion mixture into a heated (260DF.) mold, that was maintained ,' ~.

18.

1046~Z 9196 at a pressure of about 300 to 500 p.s.i. (At the catalyst concentrations employed, after 10 seconds of stirring, from 2 to 5 seconds remained within which to transfer the reaction mixture into the mold before gelation occurred.) After 3 to 5 minutes, ~he plaques were demolded and were allowed to cool .slowly to room temperature.
Table I, below, sets forth the nature and amount of the reactants, the ratio of isocyanate to hydroxyl in the reaction mixture, the catalyst and catalyst concentration, and the molding time. The novolak employed in each case was novolak A.

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~, ~ ~ ,, o ,, o ~ o o o o o ~ ~ C o o o o o o oo o o o o o ~q .
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,: .. . . : -~04~69Z 9 196 The viscosities of the polyol/novolak -solutions of these Examples were as follows:

Polyol and Polyol/novolak Wei~ht Pro~ortion Viscosity, centiPoises C, 80/20 2500-3000 at room temperature 600-700 at 60C.

A, 60/40 6340 at 70C.
9850 at 60C.
B, 60/40 9800 at 60C.

B, 80/20 1000-1300 at room temperature 400 at 60C.

Representative properties of these molded plaques are set forth below in Table II (properties were not determined on Examples 2 and 5). The test procedure employed for determining tensile strength, tensile modulus, and elongation at break ~as 20ASTM D-638.
, ' ~046692 :

bD C~ U~ ~ ~ ~ O ~ U~
E~ o ~ ~ ~ O~
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C.l .t, ~ ~ ~ ~ o~
U; C~

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~ ~ ~ ~ U~ ~ ~
H ~1 3 ~ ~ ,., ~ P 8 8 8 8 8 8 ~:; r~ ~ O Q 0 8 o ~ ~D ~U O O ~ o ~ o O o U~ : ,, .
~n o o o o o o o (~ o o ^ O O 5 0 0 0 c) ~ o o . .
Ul O O ~ O O O O O O O
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104~692 TWO-STAGE PRODUCTION OF GLASS FIBER-REINFORCED THERMOSET COMPOSITION
To a solution of 80 parts by welght of polyol C and 20 parts by weight of novolak A (total weight - 305 grams; 1.5 equivalents of hydroxyl), there was added 0.1 milliliter of a 1 M solution of disodium mercaptoacetate in ethylene glycol (0.005 weight per cent of catalyst, based on weight of polyol/novolak mlxture, and 0.009 weight per cent, based on weight of tolylene diisocyanate). Tolylene diisocyanate (145 grams; 1.7 equivalents of NC0) was added to the mixture at 60-70C., and the mixture wa~ rapidly ~ransferred to a cylindrical container, which was placed on a lathe revolving at 1000-1200 revolutions per minute. Glass fibers (1/4-inch longj 125 grams) were added to the revolving container, and were unifonmly mixed with the reaction mixture by the force generated by the spinning container. A tack-freé, B-stage composition was obtained in about 5 to 10 minutes. The material was stored at room temperature for three days, and was then compression molded (3 to 5 minutes at 190C. and 300-500 psi) into a thermoset plaque. The plaque had the following properties:
Tensile strength - 3,450 psi Tensile modulus - 143,000 psi Elongation at Break - 7.9 per cent Notched Izod Impact - 11 foot-lbs/inch of notch (by ASTM ~25~-72) :, :
23.

, ~046692 A solution of 60 parts by weight of Polyol B
and 40 parts by weight of Novolak A (total weight -150 grams; O.99 equivalent of OH) was mixed with 260 grams of TDI (3 equivalents of NCO) at 60 to 70C., without catalyst, To the resulting isocyanato -terminated prepolvmer, there was added 154 grams (1.01 equivalents of OH) of a 60:40 (by weight) solution of Polyol B: Novolak A containing 0.15 milliliter of a 1 M solution of disodium mercaptoacetate in ethylene ~ .
glycol (catalyst concentration - 0.008 weight per cent, based on weight of TDI). The reaction mixture was thoroughly mixed, and was allowed to form a tack-free B-stage composition. Compression mol~ing at 190C.
and 300-500 psi for 3 to 5 minutes yielded a clear thermoset plaque. The properties of this plaque were as follows:
Tensile strength - 7,810 psi Tensile modulus -942,000 psi Elongation at break - 1 per cent Notched Izod Impact - 7.6 foot-lbs/inch of notch An isocyanato-terminated prepolymer was produced by a procedure analogous to that described in Example 14 from 218 grams of TDI (2.5 equivalents of NCO) and 100 grams of a 60:40 (by weight) solution of Polyol B and Novolak A (0.66 equivalent of OH).

24.

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lO~ Z 9196 The prepolymer was then mixed, at 60-70~C., with 204 grams (1.34 equivalents of OH) of a 60;40 solution of Polyol B and Novolak A containing 0.15 milliliter of ~ 1 M solution of disodium mercaptoacetate in ethylene glycol (catalyst concentratlon - 0.009 weight per cent, based on TDI). The reaction mixture was then quickly ~ransferred to a cylindrical container mounted on a lathe spinning at 1000-1200 rpm. Glass fibers (1/4-inch; 140 grams) were added to the mixture, and were uniformly mixed with the reaction mixture by centrifugal force. A tack-free B-stage material was obtained in 10 to 15 minutes. Compres8ion molding of thls B-stage material at 190C. and 300 to 500 psi for 3 to 5 minutes yleLded thermo~et plaque8 having the following properties:
Tensile 8trength - 8,430 psi Tensile modulus - 1~050,000 psi E~ongation at break - 1 per cent Notched Izod Impact - 7.9 foot-lbs/inch of notch -

Claims (8)

WHAT IS CLAIMED IS:

1. A thermoset composition containing both urethane and isocyanurate groups, which comprises the reaction product of (a) a fusible novolak, (b) a polyol having at least two alcoholic hydroxyl groups, (c) a stoichiometric excess of an organic polyisocyanate, and (d) a catalytically effective quantity of a catalyst for promoting the formation of isocyanurate from isocyanate, said organic polyisocyanate being employed in an amount wherein there is at least about 1.2 isocyanato groups per equivalent of reactive hydrogen present in the reaction mixture.

2. The thermoset composition of claim 1 wherein said novolak is a composition which can be represented in simplification by the formula:

wherein x, which represents the number of phenol moieties per molecule, is a number having an average value of from at least about two to about 10.

3. The thermoset composition of claim 2 wherein said polyol is polyoxyalkylene polyol wherein the oxyalkylene units have from 2 to 4 carbon atoms.

4. The thermoset composition of claim 3 wherein the polyoxyalkylene polyol is a glycol.

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5. The thermoset composition of claim 4 wherein the polyoxyalkylene glycol is a polyoxypropylene glycol.

6. The thermoset composition of claim 2 wherein said polyol is a poly(epsilon-caprolactone).

7. The thermoset composition of claim 2 wherein said polyol is a polyester of a polyhydric alcohol and a polycarboxylic acid.

8. The thermoset composition of claim 2 wherein said novolak is employed in an amount of from about 10 to about 60 weight per cent, based on weight of novolak plus polyol.

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