CA1055639A - Free-flowing unsaturated polyester moulding compositions hardenable with very little shrinkage - Google Patents

Abstract

FREE-FLOWING UNSATURATED POLYESTER MOULDING
COMPOSITIONS HARDENABLE WITH VERY LITTLE
SHRINKAGE
ABSTRACT OF THE DISCLOSURE:

Unsaturated polyester moulding compositions hardenable with low shrinkage which are free-flowing comprise a crystalline unsaturated polyester, a copolymerisable vinyl monomer and a graft-polymerised butadiene polymer.

Description

ll~SS639 This invention relates to free-flowing moulding compositions which harden with very little shrinkage, based on unsaturated polyesters, polymerisable monomers and graft-polymerised elastomers.
Conventional unsaturated polyester resins undergo considerable shrinkage during polymerisation which is a serious disadvantage in the production of shaped articles having a satisfactory surface finish. It is known from numerous publications (German Published Speci-fication Nos. 1,694,857; 1,803,345; 1,953,062; 2,051,663;

2,061,585, French Patent No. 1,148,285~ that polyester mouId-ing compositions, with which certain thermoplasts have been mixed before hardening, can be hardened with very little shrinkage.
The above applications relate both to liquid casting resins and also to resins which have been thickened by the addition of fillers or thickeners and which, on account of their tackiness, are naturally unsuitable for the production of ~ree-flowing polyester moulding compositions in the absence of other aids. These tacky resins can only be processed into free-flowing compositions by adding such large ~uantities of fillers that the resulting poly-ester compositions can no longer be processed in in-~ jection moulding machines, in addition to which their ;~ mechanical properties generally no longer comply with f practical requirements.
According to German Published Specification No. 2 234 307 polyester moulding compositions which harden with very little shrinkage can be obtained in free-flowing form ::

. ~ - 1 - . .

l(~S563~

when they have the following composition:
a) 30 t~ 70 ~0 by weight of an unsaturated crystalline polyester containing fumaric acid radicals and . radicals of glycols correspo;nding to the general . .
. 5 formula H0-CH2-R CH2-OH, whlere R represents an alkylene of the for~ula (CH2)z (z = 1 - 18) or symmetrical dialkyl derivatives of these alkylene .;~ radicals, the alkyl substituents being situated on the same carbon atom, or cycloalkylene radicals, b) 20 to 75 ~ by weight o~ styrene, and c) 1 to 30 ~ by weight of cellulose esters o~ organic acids, such as ~or example cellulose acetates, ~; cellulose acetopropionates or cellulose ac~to-butyrates.

In order to minimise shrinkage of the polyester moulding compositions, 1t is generally necessary to ; add from 10 to 20 % by weight of a thermoplast Obviously the danger of adding thermoplastic poly-; ~ers to crystalline unsaturated polyester resins in quantities as large as these, at leas-t in the case of some thermoplasts c), is that crystallisation speed is reduced and tacky resins are obtained which are unsuitable for the production of free-flowing polyester moulding compositions in the sense o~ the present application. However, -these difficulties can be overcome by selecting special thermoplasts.

One skilled in the art would expect that the favourable mechanical properties which pure unsaturated Le A 15 499 - 2 -: - , - . . . . . . .. .. -. .. . . ....

~055639 polyester resins are known to ha~e are considerably influenced by the addition of thermoplasts. Sinee, in addition, the shrinkage has a direct linear dependence upon the ther~.oplast content in c~nventional non-free-flowing, low-shrinkage polyester moulding compositions, - ~atisfactory surface finishes and unchanged mechanical properties have hitherto ~ppeared to cancel each other out. An ideal combination was apparently not within the realms of possibility.
It has now surprisingly been found that the disadvantages referred to above can be obviated by new polyester resin mixtures eontainlng graft-p~lymerised elastomers ~9 their shrinkage-reducing eomp~nent.
Aeeor~ingly, the present invention relates to low-; 15 shrinkage moulding eompositions based on unsaturated polyesters whieh are free-flowing even in the absenee of fillers or ehemieal thickeners, eontaining A, 20 to 80 ~ by weight and preferably 30 to 50 ~
by weight, based on the sum of components A - C of a cry~talline polyester based on ~ ~-unsatura-ted diearboxy~e acid radicals,containing fu~aric aeid radicals and radicals o~ glycols corresponding to the general ~ormula H0-CH2-R-CH2-OH, in which R represen-ts an alkylene of ,- the for~ula ~CH2)x (x = O to 18), symmetrical dialkyl . 25 derivatives o~ these alkylen~ radieals, the alkyl sub-stituen-ts being situated on the same carbon atom, or cycloalkylene radicals, Lo A 15 499 ~ 3 ~

~: ~05~63~

. B. 18 to 70 % by weight, preferably 30 to 60 % by weight, based on the sum of components A - C
of polymerisable vinyl monomers, C. 2 to 50 % by weight, preferably 3 to 15 % by ~ :
weight, based on the sum of components A - C of ; a graft-polymerised elastomer, the precentages of A ~ B ~ C amounting to 100. ~ :
In the context of the invention, unsaturated . :
`. polyesters are polycondensation produc~s of fumaric 10 and/or maleic acid or their ester-orming derivatives containing a~ least 70 mol-% of fumaric acid radicals based on the acid components, with the above-mentioned ~ :
glycols, such as ethylene glycol, 1,3-propane diol, 1,4-butane diol, l,S-pantane diol, 1,6-hexane diol, 1,10- ~.
decane diol, 1,18-octadecane diol, neopentyl glycol, : 3,3-dimethyl-1,5-pentane diol and 1,4-hydroxy methyl cyclohexane. Particularly preferred diols are ethylene glycol, 1,3-propane diol, 1,4-butane diol and neopentyl glycol.
It is expressly pointed out at this juncture that maleic acid radicals inhibit the crystallisation of ,:
polyesters containing fumaric acid radicals to a far lesser extent than had been assumed, A maleic acid content of 30 mol % is not in the least troublesome.
If desired, up to 20 mol % of the sym~tetrical diols may be replaced by an equivalent quantity of :~ .
monohydric or polyhydric alcohols or asymmetrical diols, and up to 20 mol % of unsaturated dicarboxylic : ,. .: , .
.'' ,' ' ' : . ' 1~55639 acids or their ester-forming derivatives by an equivalent quantity of monocarboxylic acids or saturated dicarboxylic acids or their ester-forming derivatives (cf. J.
Bjorksten et al., "Polyesters and their Applicationl', Reinhold Publishing Corp., New York, 1956)o Examples of those alcohols include monohydric ~lcohols having 1 to 6 carbon atoms, such as methanol, ethanol, propanol, butanol, cyclohexanol; glycerol, also trim-ethylol propane, pentaerythritol, allyl alcohol, dieth-ylene glycol, triethylene glycol and partial etherif-ication products of the aforementioned polyhydric alcohols, such as allyl, methallyl, ethallyl, chlorallyl and crotyl ether~. Examples of tho~e acid components ;~¦are o-phthalic aoid, isophthalic acid, terephthalic acid, hexahydrophth~lio acid, tetrachlorophthalic acid, endomethylene tetrahydrophthalic acid, hexachloro-endomethylene tetrahydrophthalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, benzoic acid, acrylic acid and methacrylic acid or the ester-forming derivatives of these acids.
The incorporation of these esterification components lowers the melting point of the crystalline, unsaturated polyester, which can be advantageous to a certain extent, especially in the case of crystalline polyesters which normally have a very high melting point, because a very high melting point complicates the incorporation of fillers and other additives.
The dicarboxylic acid or its derivatives and the glycols are reacted at elevated temperature, preferably at temperatures in the range from 150 to 210C, until a product having an acid number below 100 is obtained.
The acid numbers of the unsaturated polyesters s]hould Le A 15 499 - 5 -be from 10 to 100, preferably from 20 to 70, whilst their - hydroxyl nu~bers should be from 10 to 150, pre~erably ~rom 20 to 100. The molecular weights of the polyesters may fluctuate within a wide range, although they are normally in the range from 500 to 5000 and pre~erably in the range ~rom 1000 to 3000 (measured by vapor-pressure osmosis in dioxane and acetone).
Polymerisable vinyl mon~mers suitable for the purposes of the invention include the unsaturated compounds normally encountered in polyester technology which preferably contain a-substituted vinyl groups or ~-substituted allyl groups such as, for example, nucleu~-chlorinated and -al}cy~ated styrenes, the alkyl groups contAining from 1 to ll carbon atoms such ~s for ex~mple styr~ne, vinyl toluene, divinyl ben~en~, ~-meth~l styrene, tert.-butyl styrene, chlorostyrenes, vinyl acetate, optionally in admixture with small quantities of acrylic acid and methacrylic acid and/or their esters having 1 to 4 carbon atoms in the alcohol component, acrylonitrile and methacrylonitrile, allyl esters such as allyl acetate, allyl(meth)acrylate, phthalia aoid diallyl ester, triallyl phosphate and triallyl cyanurate.
Graft-polymerised elastomers suitable for the purposes of the invention are those which can be produced by polymerisation of b) in the presence of a~, a) denoting 10 to 90 % by weight, preferably 45 to 90 % by weight, based on component C of a rubber-elastic butadiene polymer with up to 50 % by weight, based on a) of copoly-merised styrene, acrylonitrile, methacrylonitrile and/or acrylic methacrylic acid esters ha~ing 1 to 18 carbon atoms in the alcohol component, and Le A 15 499 : - . , , : - ,, . ~ . ,., ,; ; - , , 1~55639 b) denoting ~rom 90 to 10 % by weight, preferably from 55 to 10 % by weight based on component C of styrene or with styrene copolymerisable monomers such as, ~or example, acrylonitrile, methacrylonitrile, esters of acrylic acid and methacrylic acid having 1 to 18 carbon atoms in the alcohol chain, styrenes substituted by halogen atoms or aliphatic radicals having 1 to 6 carbon atoms, such as ~-methyl styrene, tert.-butyl styrene, vinyl toluene, divinyl benzene, chloro-styrenes or mixtures thereof. The percentages of a) + b) amount to 100.
Instead of using the optionally modified rubber-elastic butadiene polymers a), it is also possible to use isoprene polymers, rubber-elastic polyacrylic acid esters, EPDM-rubbers and polypen~tenamer/polyhexenamer rubbers.
The gra~t-polymerised elastomers are produced in known .~anner either in solution or in emulsion. They can show any particular stereospecl~icity and, in the case of copolymers, any particular distribution of the monomer components in the , polymer chain. The rubber-elastic butadiene polymers usually j 20 have a glass temperature~according to K. H. Illers and H.
Breuer, Kolloid-Zeitschrift ~ , 110 (1961)] of below 0 C, preferably below -30 C.
The mixtures according to the invention contain conv~ntional polymerisation inhibitors, which prevent premature, uncontrolled gelation, in the usual quantities, preferably in quantities of from O.OOl to O.l % by weight.
Suitable polymerisation inhibitors include phenols and phenol derivatives, preferably sterically hindered phenols whlch contain alkyl substituents having l to 6 carbon atoms in both o-positions to the phenolic hydroxy group, amines~ preferably secondary aryl amines and their derivatives, quinones, copper s~lts of organic acids, addition compounds of Cu(I)-halides Le A 15 4gg _ 7 _ ~OSS639 with phosphites9 such as for example 4,4'-bis-(2,6-di-tert.-butyl phenol), 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxy benzyl)-benzene, 4,4~-butylidene-bis-(6-tert.-butyl-m-cresol)9 3,5-di-tert.-butyl-4-hydroxy benzyl phosphonic acid diethyl ester, N,N'-bis-(~-naphthyl)-p-phenylene diamine, N,N~-bis-(l-methyl heptyl)-p-phenylene diamine, phenyl-~-naphthyl ~aine, 4,4'-bis-~,a-dimethyl benzyl)-diphenyl amine, 1,3,5-tris-(3,5-di-tert.-butyl-~-hydroxy hydrocinnamoyl)-hexahydro-s-triazine, hydroquinone, p-benzoquinone, toluhydroquinone, ~-tert.-butyl pyrocatechlol, chloranil, naphtho~uinone, copper n~phthenate, copper octoate, Cu(I)Cl/triphenyl phosphite, Cu(I)Cl/trimethyl phosphite, Cu(I)Cl/trischloroethyl phosphite, Cu(I)Cl/tripropyl phosphite and p-nitroso-dimethyl aniline.
The polyester moulding compositions according to the invention contain the usual quantities, preferably from 0.1 to 5 ~ by weight, of polymerisation initiators such as, for example, diacyl peroxides such as diacetyl peroxide, dibenzoyl peroxide, di-~-chloroben~oyl peroxide, peroxy esters such as tert.-butyl peroxy acetate, tert.-butyl peroxy benzoate, dicyclohexyl peroxy dicarbonate, alkyl peroxides such as bis-(tert.-butyl peroxy butane), dicumyl peroxide, tert,-butyl cumyl peroxide, hydroperoxides such as cumene hydro- -peroxide, tert.-butyl hydroperoxide, cyclohexanone hydroperoxide, methyl ethyl ketone hydroperoxide, ketone peroxides such as acetyl acetone peroxide, or a~oiso-butyrodinitrile~

Le A 1~ 499, - 8 -:' - ., .
; ' ~ .

1~)55639 Chemical thickeners may be added in quantities of froln 0.1 to 10 % by weight and preferably in quantities of from 0.5 to 5.0 ~ by weight, based on the sum total of` components A to C. In the conte~t of the invention, chemical thickeners are the oxide~ and hydroxi~es of the metals of the Second ~ain Group of the Periodic System, especially magnesium and calcium, to which sm~ll quantities o~ water may optionally be added.
In addtion, up to 300 ~ by weight and preferably from 50 to 200 % by weight, based on A to C o~ fillers may be added to the polyester compositions according to the invention. Suitable fillers are inorganic materials,such as ; c~lcium carbonate, silicates, aluminas, lim~, oarbon, asbestos, ~lass, metnls, especi~l]y in the form of fibres, woven ~abrics or mat~ and organic fillers such as cotton, sisal, jute, polyester, polyamide, ; again in the form of libres of woven fabrics.
In addition, inorganic or organic pigments, dyes, lubricants and release agents such as zinc stearate, UV-absorbers, etc., may of course a~so be added in the usual quantities if desired.
Thc composition according to the invention is prefer-ably homogenised at a temperature at which the unsatur-ated polyester exists in molten form, i.e. at temperatures in the range fro~ 70 to 120C, so that the solutions o~
the molten crystalline polyester in pol~nerisable vinyl monomers or the molten polyesters themselves are mixed with the graft~polymerised elastomers which may optionally be present in admixture with polymerisable vinyl monomers. All other fillers and additives may be added together with the individual ColDpOnentS Cooling of the mass to room temperature gives a readily ~2 - 9 _ ` 105563g grindable, non-agglomerating ~ree-flowing moulding composition which can be heat-hardened in heated moulds to form low-shrinkage mouldings. A free-flowing granulate can also be produced for example by impreg-nating a glass fibre strand with th~e unstrengthened mixture under heat and after cooling to room temperature chopping the strand into a granulate.
In cases where the polymerisation initiator is added as described to -the molten mixture according to the invention, care must be taken to ensure that its decomposition temperature is distinctly (approx. 20C) above the melting temperature ol the crystalline polyester.
If the polymerisation initiator is present in solid, free-flowing form, it may also be added to the free-flowing mixture atroom temperature, provided that the free-flowing mixture is suitably fine-grained.
The moulding temperature is preferably in the range from 120 to 180C, and most preferably about 140C. The moulding time is generally from 2 to 10 minutes, preferably about 4 minutes, for a moulding pressure of from 10 to 100 kp/cm2.
The mix-ture according to the invention, for example with a vinyl monomer content of 40 %, are compositions which are solid and free-flowing at room temperature, even in the absence of fillers, which is all the more surprising insofar as the ability of the crystallisable unsaturated polyesters to crystallise out in molten form from aromatic vinyl compounds to form a solid mass with inclusion of aromatic vinyl compounds is lost by the addition of conventional thermoplasts, for example polystyrene, polymethyl methacrylate or cellulose acetobutyrate, or takes Le A 1~ 499 - 10 -~055639 too much time.
Considerably lar6er quantities of vinyl monomers may be added to the mixtures according to the invention, especially where graft polymers with a high rubber content are used, than to the crystalline polyesters without any addition of graft polymers, without any loss of fluidity.
The compositions change into a paste-like form which is of particular advantage because the shrinkage of the - mouldings can be further reduced by increasing the vinyl monomer content of the moulding compositions.
It has also been found that the shrinkage which the mouldings undergo is a minimum with a graft polymer content of from 5 to 10 % by weight, based on the three-component system without any other additives. The degree of shrinkage increnses again both with smaller and with larger quantities of graft polymer. This is all the more surprising since the shrinkage effect has a direct linear dependence upon the thermoplast content in conventional, non-free-flowing low-shrinkage moulding compositions, in which an addition of from 10 to 20 ~
by weight of thermoplast is required to obtain minimal shrinkage. In view of the small quantity of graft polymer required, the polyester moulding composltions according to the invention retain the well-known, valuable properties of thermoplast-free polyester moulding compositions.
It has also been found that the freedom from shrinkage of hardened mouldings is dependent -to a very large extent upon the styrene compatibility of the polyester used, styrene-incompatible polyester~; Kiving moulding compositions with the least shrinkage, whilst styrene-compatible polyesters give moulding compositions Le A_15 499 - 11 -~OS56;~

with greater shrinkage.
The styrene compatibility or even styrene solubility of unsaturated polyesters is a l~el:L-known concept in the chemistry and technology o~ unsnturated polyester resins: cf. Johannes Scheiber, "Chemie und Technologie der kunstlichen Har~e", vol. I, "Die Polymerisathar~e", Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, 1961, 2nd. Edition, pages 563 et seq, more especially pages 566 and 571/572.
The styrene compatibility of unsaturated polyesters expressed in % by weight of unsaturated polyester, based on the total quantity of unsaturated polyester and styrene, is defined nnd determined as follows:
Unsnturated polyeqter is dissolved in ætyrene at 110C in exactly the quantity required to obtain a clear qolution of known concentration. More styrene is then added with stirring to the resulting solution until it clouds. The concentration, based on the total quantity of styrene and unsaturated polyester, of the unsaturated polyester in % by weight at the clouding point is defined as styrene compatibility.
The clouding point can be made easier to deterrnine by using a black background during dilution with styrene.
The styrene used preferably contains an inhibitor, for example 0.2 ~ by weight of tertl-butyl pyrocatechol in order to prevent hazing by foreign substances, for example polystyrene, which would only complicate the determination.
The following exal~ple serYes as an illustration:
E (g) = quantity weighed in ~in grams), for example 20 g of the clear polyester solution in styrene, the solution having a concentration of P %
Le A 15 499 - 12 -~55639 o~ unsaturated polyester P (%) = the concentration ~in ~p by weight), o~
unsaturated polyester dissolved -to form a clear solution in styrene, for example 60 %
S (g) = quantity o~ styrene in grams a~ded to obtain the clouding point, for example 10 g Styrene compatibility = E (g) . P (~) E (g) ~ S ~g) for example 20 g . 60 %
20 g ~ 10 g By definition, there~ore, styrene compatibil:ity is greater the lower the percentage.
Experience has shown that the styrene compatlbility of ~n unsaturated polyester ix influenced by the polyester components involved in its synthesis, i.e. by the acids and hydroxy co~pounds used in -the syn-thesis of the polyester.
Esterification components which cause styrene in-compatibility are, for example, maleic acid and i-ts ~0 anhydride, fumaric acid and ethylene glycol.
Esterification components which cause styrene compatibility are, for e~ample, phthalic aoi~, isophthalic acid, tetrachlorophthalic acid, hexachloro-endomethylene tetrahydrophthalic acid or their anhydrides, 1,2-propane diol, 1,3-butane diol, neopentyl glycol and trimethylol propane allyl ether.
As already mentioned, the more styrene-incompatible the unsaturated polyester and the greater the quantity of styrene present in the mixture produces a lower shrinkage of hardened mouldings. Styrane-incompatible polyesters containing more styrene than corresponds to their styrene compatibility "repel" the styrene and give Le A 1~ 429 - 13 -., '~,.

wet mouldin~ com~o.~itions from which it is only p~ssible to nbtain unusa~le, bu~ble-contain:ing and heavily distorte~ moul(lings. These faults, together with the loss Or fluidity, c~n be avoided by adding the graft-p~lymerised elastomers accorcling to the invention.
El~stomers with a high rubber content are most capable of ~inding the styrene repelled by the polyester. As cnn be seen from the Examples, mouldings based on these combinations are those wi-th the lowest shrinkage.
The properties of thc hardened polyester mouldings are influenced not only by the styrene compatibility of the polyester ~nd the ty~e and quantity of thermo-plast added ~ut also ~y processing which also determincs the degree of shrlnkage; cf. Sch~ -Wal~ and 0. Walter, Kunststorf-Rundsohau, 1972, No. 11, page 592:
1. Mouldings in which the glass fibres are arranged in the moulding direction shrink to a far lesser extent than mouldings in which the glass fibres are arranged transversely of the moulding direction.
2. Shrinka~e increases with increasing moulding pressure.

3. Surface gloss and smoothness increase with increasing mould tempera-ture. However, i-r n certaLn temperature is exceeded, ~ull patches appear.

4. Surface gloss can be considerably increased by ex$ending the moulding time,

5, The tendency towards speck formation is reduced to an e~tent which is greater, the more slowly the catalyst system reacts, i.e. the higher the initiation temperature of the catalyst.
To sum up, lt can be said that the reaction-induced shrinkage of a low-shrinkage polyester resin is governed by pressure. This means not only that the degree of Le A 15 499 - 14 -1~355639 shrinlsage differs according to the ~noulding pressure, bllt also thnt it varies ~ithin the mou~ding itself depending upon position, direction, glass fibre orientation or material thickness.

_Yampl~s and Comparison Tests Percentages are percent by weight.
Production ~ the unsaturated polyesters (UP) The unsatura-ted polyesters are obtained in known manner by melt condensation. They are stabilised with 0.02 ~ of hydroquinone, based on the unsaturated - polyester. The composition of the polyesters, and their characteristics, are set out in the following Table.
~P 1 UP 2UP ', UP
F~ arl( acid g 1160 11601160 Malcic ac~(t anhydride g - - - 980 i Ethylenc glycol g 682 - - -1,3-propane diol g - 798 - -1,4-butane diol g - - - 945 Neopentyl glycol g - - 1071 Characteristics Acid number [mg KOH/g] 48 38 35 l~2 Styrene compatibility 71~ 38~ '2~ ~ 2%
Cr~stallisation behaviour in solution in s~yrelle Clouding temperature (C) 63 98 85 93 Solidification temperature 57 90 83 74 fumarate (according to N~-spectrum3 100 100 100 73 ~ .... ...
Styrene compatibility was determined in test tubes in the same way as described above.

Crystallisation behaviour was determined as follows:

2 g of styrene containing 002 % by weight of ~-tert.-., 1~55639 b~tyl T)yrocatechol were diss~lved at ahout 120C in 8 g o-f molten, unsaturated polyes-ter in a test tube (~iameter l& mm, Icngth 1~0 mm), nnd th~ solution left to cool to room temper~turc wl~ile s-tirring with a thermomcter.
The ~emperature at which th~ solution hccame c10udy throu~h the lorma-tion of the first few crystal seeds is called the clouding temperature, whilst thc temperature at whic}l the solution solidified is called the solid-iricntion temperatllre., graft~})olymerised elastomer E ], prcpared from 8() ~ of ~L polybutadiene rubber graft-polymerised in a~lueous-emulsion with 18 ~ of styrene nnd 2 ~0 of acry-lonitrilo, was used ror thc ~ollowing tests, The polyl)uta~lcne rubber used was a coarse-pArtiole te~ hnvlng arl avcrllge particle si~e ol from 0.25 to o.65 ,u, the grafting base, tested in the form of solid rubber, having n gel content of 80 ~ by weight and a Mooney viscosity of ~0 ML-~, as measured in accordance with DIN 53 52~. The polybutadiene rnbber was prepared 2() by emulsion polymerisation at ~5 to 80C.
Production of the 3-oomPonent systems Group 1: Variation of the polye.sters To prcpare the 3-component systems according to the invention, batches of 5 g of the graft-polymerised elastomer E 1 were impregnated with 40 g of styrene, containing 0.02 ~ by weight of benzoquinone in dissolved form, the resulting mass was heated to 80C and batches of 55 g of the molten, unsaturated polyesters UP 1 to UP 4, ~eated to 110C, were allo-Yed to flow in with stirring. Cooling of the mixtures at the temperatures indicated produced solid, free-flolYing compositions which are designrLted UP l/E 1 to UP 4/E 1 and ~YhiCh represent the Le A 15 ~99 - 16 -~5563~

n~ c; O r Gro~
~i r oul) 1:
k~ nl) 1 e: UP l/E 1 IJI' 2/~ 1 Ul' 3/E 1 U~ 4/E 1 Sol-i(lil`icntiorl telllpe:r~tnre: 61 ~ 7~ 73 ComF)orlent sy.stems, in which the qu.lnt:ity of gra~`t-ol~merisc(l elastomer E 1 w~s rcp:klced by the unsatur~te(l l)olyc~;ter for comp~?ris~ i th the 3-component ~ystemg nccor(~itlg to the invention, l~erc llsed rOr com~)rlri son tests. Tl~ese co-nparison compositions arc designatod UP l/V to UP ~I/V nnd, herlce, COtlSiSt of 40 % of' styrene nnd GO $ of unsaturated po].yester.
ro!~ 2': V riat.ion o~ th_ e ~rart-pol~neri.sefl elastolners .~n tho ;I'ol.lo~in~r l~,~nm~los, thc systcm UP 3/E 1. ~a~
mo(lif.io~ t;o thc extent that elastomors E 2 and E 3, ~ith the follo~in~ composi-tiotls, ~ere used instea~ of the ~ra-ft-polytnerise(l elastomer E 1:

Po lybllta(lietle rubber content: 50 ~
Styrene content: 3G ~ 63 ~O
Acrylonitr.ile cl)ntcnt~ 25 Tho compo~it:ion ol the satnples con-tflinin~ these elastolllers and their solidification temperatures are shown in the fol.lowin~ Table:

,, .
~ .Yamples UP 3/E 1 UP 3/E 2 UP 3/E 3 . __ . ~_ ~ __ UP 3 contcnt: 55 ~O 55 % 55 %

Styrene content: 40 ~p 40 ~O 40 E 1 content: 5 %

E 2 content _ 5 O

E 3 content: - - 5 %
. .

Le 15 4~9 - 17 -1~551639 Solillifio~ltioll lol1l~)eruture 7'(' ()()~'~ G7(, Grollp 3: Vnriat ion o~ tlle (~allt,i l;~ ol ~;r.l:l'l, poly!nf~r 1~: 1 In t~l~f? I'ollOWi 11~ inmples, 1~ Ig ol the XamI)lf~?
III' I/E ] l~S Ino(lifi((l to tlIc~ ex~eIIl tlIat polyest~?r IJP 1 r~ Iy r~ ?(l ~v ~r(lft I)olyllIer E 1.
Com~)osit~iolI of Groll~
?IJl' 1/~ JP l/U I Ul' l~ P l/E 13 , III' 1 oontont:57 ,0 55 tfff 50 50 ~ 5 /'o E 1 C 011 t f~?rl t: 3 ,~ 5 ,c 1(),~, 15 ,' 1( Styrell(? COIltent:40 ~ 1lO ,f /10 ~j~ /10 Group ~: Variatiotl ol the styren~ conten-t In the ~ollowing Examp1es, mi~ing of the salIlple ur l/E 1 was moclit`ied to -the extent -that polyester UP 1 ~as increnslngly replaced ~y styrene.

Conl~ositlon o~ Group l~
E~alnple UP 11/~ 1UP 12/~ 1UP 1/~ 1UP 13/E 1 UP 1 content: 80 ~D65 ~ 55 ~ 45 %
E I content: 5 ~ 5 ~ 5 ~ 5 ~
Styrene content: 15 ,'0 30 ,~ 40 ,~0 50 %
Production of harden~ble, free-flowin~ pol~ester mouldin~
compositions To assess the 3-component rnixtures according to the invention, the compositions ~ere m~]te(l at approximately 2~ 80C in a heated kneader and homogeneously kneaded with the a~ditives indicated below. Finally, the peroxide was added and the mi~ture subsequently cooled to room temperature, resulting in the formation of free-flowing llardenable compositions.
100.00 parts by weight of mixture according to the invention and comparison mixture 100.00 parts by weight of calcium carbonate 1,50 parts by weight of magnesium oxide 4.00 parts by weight of ~.inc stearate Le ~ 15 499 - 18 -,. " ,; ,. . . .

~L~55~i3g 5 parts ~)y weig~lt of iron oxide l)lack .35 par~s by wei~ht ol` iron oxide red .75 parts by weight Or tert.-butyl perben~oate In the ca~e oi t~le sampl~s corltairling the l)olyester U~' ', I;he mixture was mixed ~ith the additives at ll~C
and~ ins-tea(l of the tert.-butyl perhen~oate, dicumyl per-oxide powder was added to the cooled, -ri~e~ rticle ~nass at room temperature.
Reinforcing f`ibres were deliberately not added hecause, 1() as already mentioned, they promote irregular shrinkage in view of` the diYferent orientation of the fibres.
Arter ~tornge ror 1 day at room temperature, the poly-ester moulding composition were moul~led in a ~leat~d lab-oratory press to form oylindrtcal mouldirlgs oach weighing 1~ g for a height of approxima~tely ~5 mm.
The mould used was in the ~orm of an oil-heated and oil-cooled cylinder with an internal diameter o~ 20 mm which was closed by a piston ~t its upper and lower ends (Bosch-diesel-injection pump). The material was introduced at ~0 30C. The upper piston was loaded through a lever arm with a pressure of 25 and 50 kp/cm~ and the moulcl heated to 140C. The displacement of the upper pistorl was recorded as a i`unc-tion of time by means of an inductive displacement pick-up (cf. upper part of the graph). A point containing a thermocouple projected into the moulding from the lower piston. The temperature pattern obtained in the moulding as a functionof time is shown in the lower part of the graph. After the exothermic reaction had adated i.e. after 7 minutes, the mould was cooled to 30C~
The symbols used in the graph have the following meanings:
a) Composition introduced, mould closed, composition Le A 1~ 499 - 19 -1~55639 ~lei~t~ nd expclnds I)) Co~position ~lcls almost reaclled the tnouldill~ temper-~Itllre re.lCtiOn begillS, COlllpt)Si tiOII Sllrink.4 thrOUg}l polymeri~sation-induced shrink~ge c) Temperature max:imuln, reacti(>n and polymerisation shrillk.ige lar~ely over, mass ~ools to the temperature of the mould and shows limite(~ heat shrinkage ~) ~loul~l is cooled, mouldillg shows heat shrinkage e) l~oom temperatllre re~chetl I() i~ denotes the polymerisation-induced shrinlcage, n is the maximum linear expansion, C is the heat-induced s~lrinl~age.
A and ~ wer(? associnted ~y the follow:in~, rol~ltion:
llellltive shrinkage S (rel) = A . 10()/~1, The valuc (, was su~stantially the samc in all tests and was ignored. Since in a].l æamples the quantity and type of additives were kept constant, S (rel) prov:ides a clear indication of the shrinkage properties of the mixtures according to the invention.
2() The rel~tive shrinkage v~lues :~ound in the moulding compositions UP l/E 1 to UP 4/E 1 accord.ing t~ the invention ~nd in the correspon~ing comparison samples UP l/V to UP l~/V
are sho~n in groups in the following Tablc:

S (rel) of Group 1 (Variation of the pol~esters~ :
S (rel) 2 2 under 25 kp/cmunder 50 kp/cm Samples moulding pressure ~oulding pressure UP l/E I 11~ ~ 19 %
UP l/V distorted distorted UP 2/E 1 44 ~ 60 UP 2/V 52 % 65 ~
UP ~/E 1 ~3 ~ 61 ~ `
Le A ~ 99 1a~55639 UP 4/E I 4 7 % f;' 5 UP ~/V 55 $ 68 ~

__ All the UP/E 1 moulcling compositions show less rela-tive shrinkage than the comparison samples UP/V. UP/E 1 shows ' the leas-t relat:ive shrinkage on nccoun-t of -the poor styrene :. compatibility ol the polyes-ter IJY 1.

S ~rel) of Group 2 (Variation of the ~raft-pol,ymerised '.
elastomers) .
S (rel) 2 under 25 kp/om under 50 Isp/cm2 Exumples mould.ing pressuro moulding pressure - --- _, UP 3/E 1 43 $ 61 UP 3/E 2 46 % 56 %
UP 3/E 3 54 ~ 67 %
UP 3/V 62 ~ 70 ~0 All the snmples show less relative shrinlcage compared with the comparison sample UP 3/V.
S ¢,rol~ Or Group 3 (Variation o:f ~ ntit~ of~ aft pol~1ner) S rel under 25 kp/cm2 2 Example moulding pressure under 50 kp cm . _ . . . _ . . . _ .
25 UP l/E 11 28 % 55 %
UP l/E 1 14 % 19 %
UP l/E 12 23 ~ 33 %
UP l/E 13 32 ~0 48 %

Example UP l/E 1, with a graft polymer content of' 5 show lowest relative shrinkage. Smaller quantities of UP l/E 11) and, in particular, larger quantities of graft Le A 15 ~99 - 21 -1~5~639 polymer UP l/E 13) produced distinctly higher relative shrinlsa~e values.
S (rel) o~ Group 4 (Variation of the styrene ntent) under 25 })sp/cm2 under 50 kp/cm2 Example moulding pressurc moulding pressure . . .
UP ll/E 1 46 % 76 %
UP 12/E 1 23 ~ 49 ~o UP l/E 1 14 % 19 %
~ UP 13/E 1 11 ~ 12 ~0 . . . ,_ These Examples show distinetly decreasing shrinkage : values with increasing styrene oontent of the mixtures.

Le A 15 499 - 22 -. .. , .. . ,:. .. ~ . :.. . . ~ . , : .. . . : . .

Claims (6)

CLAIMS:

1. Low-shrinkage moulding compositions based on unsaturated polyesters which are free-flowing even in the absence of fillers or chemical thickeners containing A. 20 to 80 % by weight, based on A to C of a crystalline polyester based on?, .beta.-unsaturated dicarboxylic acid radicals, containing fumaric acid radicals and radicals of glycols corresponding to the general formula HO-CH2-R-CH2-OH, in which R represents an alkylene of the formula (CH2)X (x = O to 18), or symmetrical dialkyl derivatives of these alkylene radicals, the alkyl substituents being situated on the same carbon atom, or cycloalkylene radicals, B. 18 to 70 % by weight, based on A to C of polymerisable vinyl monomers, C. 2 to 50 % by weight, based on A to C of a graft-polymerised elastomer which can be produced by polymerisation of b) in the presence of a), a) denoting 10 to 90 % by weight, based on component C of a rubber-elastic butadiene polymer containing up to 50 % by weight, based on a) of copolymerised styrene, acrylonitrile, methacrylonitrile and/or acrylic or methacrylic acid esters having 1 to 18 carbon atoms in the alcohol component, and b) denoting 90 to 10 % by weight, based on component C of styrene or with styrene copolymerisable monomers, the per-centages of A + B + C and of a)+b) amounting to 100.

2. Free-flowing moulding compositions hardenable with low-shrinkage of the kind claimed in claim 1, in which up to 20 mol % of the symmetrical glycols is replaced by the equivalent quantity of monohydric or polyhydric alcohols or asymmetrical diols, and/or up to 20 mol % of unsaturated dicarboxylic acid radicals by the equivalent quantity of monocarboxylic acid radicals or saturated dicarboxylic acid radicals.

3. Free-flowing moulding compositions hardenable with low-shrinkage the kind claimed in claim 1, additionally containing from 0.1 to 10 % by weight, based on the 3-component mixture according to claim 1, of oxides and/or hydroxides of the metals of the Second Main Group of the Periodic System.

4. Free-flowing moulding compositions hardenable with low-shrinkage of the kind claimed in claim 1, additionally containing up to 300 % by weight, based on the 3-component mixture according to claim 1, of one or more fillers from the group comprising calcium carbonate, silicates, aluminas, lime, carbon, asbestos, glass, metals, cotton, sisal, jute, polyesters, polyamide.

5, A process for the production of free-flowing moulding compositions hardenable with low shrinkage of the kind claimed in claim 1, wherein components A, B and C are homo-genised at a temperature in the range from 70 to 120°C.

6. Mouldings hardened with low-shrinkage produced from the free-flowing moulding compositions claimed in claim 1.