Mixtures of polyurethanes and unsaturated polyester resins

Unsaturated polyester resins containing--as additive--polyesterurethanes having free carboxyl groups and/or terminal radically polymerizable double bonds are good starting materials for manufacturing moulded articles with outstanding properties, particularly with an excellent impact strength.

This invention relates to mixtures of .alpha.,.beta.-ethylenically 
unsaturated polyesters, vinyl or vinylidene compounds copolymerisable 
therewith and polyurethanes containing carboxyl groups and/or at least one 
terminal polymerisable double bond per molecule, from which hardened 
mouldings with improved mechanical properties can be produced. 
Japanese Patent Specification No. 19,696/72 describes mixtures containing 
an .alpha.,.beta.-ethylenically unsaturated polyester, vinyl monomers and 
a polyurethane which does not contain any free isocyanate groups. These 
mixtures are used for the production of moulding compositions which can be 
hardened to form low-shrinkage and low-distortion mouldings having a 
smooth surface. According to the description, the mechanical strengths of 
mouldings such as these (i.e. their flexural strength and stiffness in 
flexure) are no better and, if anything, slightly worse than those of 
mouldings which do not contain any polyurethane. According to the Japanese 
specification in question, the moulding compositions are produced by wet 
pressing. 
One extremely rational and widely used method of processing unsaturated 
polyester resins is the resin mat process. In this process, the polyester 
resins are mixed with fillers, polymerisation initiators, auxiliaries and 
chemical thickeners, such as magnesium oxide for example, and glass fibre 
mats are impregnated with the resulting mixture and covered on both sides 
with masking film. After a ripening period of 1 to 3 days, the reaction of 
the chemical thickener with the unsaturated polyester resin causes the 
mass to harden to such an extent that the masking films can be removed 
without damaging the mat. The tack-free resin mass can be conveniently cut 
to size in this form and hardened in a heated press to form mouldings. 
One significant disadvantage of mouldings produced from standard commercial 
unsaturated polyester resins, either by the resin mat process or by any 
other process, is their extreme brittleness which seriously restricts 
their use in various fields such as, for example, the motor vehicle 
industry. 
It is known from the literature that, by incorporating shrinkage-reducing 
elastomeric additives in unsaturated polyester moulding compositions, it 
is possible at the same time to obtain a gradual improvement in the impact 
strength of mouldings produced therefrom (cf. for example German 
Auslegeschrifts Nos. 1,166,467 and 1,241,983 and U.S. Pat. Nos. 3,668,178; 
3,882,078; 3,857,812 and 3,674,893). In this case, however, the inadequate 
compatibility of the elastomeric component with the solution of the 
unsaturated polyester resin in vinyl monomers causes difficulties either 
in the handling of the polyester resin or of the polyester resin 
composition produced therefrom by the incorporation of additives or in 
regard to thickening with chemical thickeners, in which case the resin 
mats obtained have a tacky surface so that, in many cases, the masking 
films cannot be removed without damaging the resin mat, or in regard to 
the hardened moulding which, although having reduced shrinkage, is also 
unevenly pigmented and patchy with only a slight improvement, if any, in 
impact strength. When mouldings of this type come into contact with 
solvents, for example during lacquering, the elastomeric additives can be 
swollen and dissolved out so that the otherwise usual favourable 
resistance to chemicals of the hardened unsaturated polyester resin 
compositions is lost. 
Accordingly, there is a need for unsaturated polyester resins which, in 
solution in vinyl or vinylidene monomers, have as far as possible only a 
single phase, which can be thickened as required with chemical thickeners 
without separating and which, after hardening, give high-impact mouldings. 
It has surprisingly been found that unsaturated polyester resins containing 
additions of polyurethanes with carboxyl groups and/or at least one 
terminal radically polymerisable double bond per molecule satisfy the 
above-mentioned requirements and give mouldings having outstanding 
properties. 
Accordingly, the present invention provides mixtures of 
(A) 20 to 70 parts by weight of at least one .alpha.,.beta.-ethylenically 
unsaturated polyester containing at least three double bonds per molecule, 
(B) 20 to 70 parts by weight of at least one vinyl or vinylidene compound 
copolymerisable with (A), and 
(C) 3 to 30 parts by weight of at least one polyurethane, characterised in 
that the polyurethane (C) 
(i) is either free from carboxyl groups and contains at least one terminal 
radically polymerisable double bond per molecule, or 
(ii) does not have a copolymerisable double bond, but contains carboxyl 
groups corresponding to an acid number of at least 8 (based on 
polyurethane C), or 
(iii) contains at least on terminal radically polymerisable double bond per 
molecule and carboxyl groups corresponding to an acid number of at least 8 
(based on polyurethane C). 
The present invention also relates to the use of these mixtures for the 
production of thickened resin systems. 
In order to clarify the invention, some of the expressions used in the 
specification are explained in the following: 
"unsaturated polyesters A" are compounds free from urethane groups; 
"double bonds per molecule" means the quotient of the number of 
analytically detectable double bonds and the average molecular weight (for 
the method of determination, see below); 
"polyurethanes C" are polyurethanes containing both ester bonds and also 
urethane bonds, these polyurethanes containing at least 0.01 equivalents 
of urethane groups per 100 g of the polyurethane. 
"terminally unsaturated" or "terminal radically polymerisable double bond" 
means that the first carboxylic acid or dicarboxylic acid residue, 
counting from the ends of the polymer chain, contains a polymerisable 
ethylenically unsaturated double bond, whilst the rest of the molecule 
does not contain any further ethylenically unsaturated (polymerisable) 
double bond. 
The unsaturated polyesters (A) used in accordance with the invention may be 
obtained in conventional manner by polycondensing at least one 
.alpha.,.beta.-ethylenically unsaturated dicarboxylic acid containing from 
4 to 6 carbon atoms (or ester-forming derivatives thereof), optionally in 
admixture with one or more C.sub.4 -C.sub.20 - dicarboxylic acids which do 
not contain any unsaturated aliphatic groups (or ester-forming derivatives 
thereof), with at least one dihydric alcohol containing from 2 to 30 
carbon atoms. Preferred unsaturated dicarboxylic acids which do not 
contain any unsaturated aliphatic groups, or derivatives thereof, are 
phthalic acid or phthalic acid anhydride, isophthalic acid, terephthalic 
acid, hexahydro- or tetra-hydro-phthalic acid or their anhydrides, 
endomethylene tetrahydrophthalic acid or its anhydride, succinic acid or 
succinic acid anhydride and succinic acid esters and chlorides, glutaric 
acid, adipic acid, sebacic acid and trimellitic acid. In order to produce 
flame-resistant resins, it is possible to use, for example, 
hexachloroendomethylene tetrahydrophthalic acid, tetrachlorophthalic acid 
or tetrabromophthalic acid. Flame resistance may also be obtained by 
adding halogen-containing compounds which are not co-condensed with the 
polyester, such as chloroparaffins for example. Preferred polyesters 
contain maleic acid residues, of which up to 50 mole % may be replaced by 
phthalic acid or isophthalic acid residues. Preferred dihydric alcohols 
are ethylene glycol, 1,2-propane diol, 1,3-propane diol, diethylene 
glycol, dipropylene glyocl, 1,3-butane diol, 1,4-butane diol, neopentyl 
glycol, 2-ethyl-1,3-propane diol, 1,6-hexane diol, perhydrobisphenol, 
alkoxylated bis-phenols etc. The polyesters may have acid numbers of from 
1 to 100, OH-numbers of from 10 to about 150 and theoretical molecular 
weights in the range of from about 500 to 10,000 and preferably in the 
range of from about 700 to 3000 (based on the acid and OH-numbers). 
In the context of the invention, preferred copolymerisable vinyl and 
vinylidene compounds B are unsaturated compounds of the type commonly 
encountered in polyester technology which preferably contain 
.alpha.-substituted vinyl groups or .beta.-substituted allyl groups, 
particularly styrene, but also, for example, nucleus-chlorinated and 
nucleus-alkylated or alkenylated styrenes, the alkyl groups containing 
from 1 to 4 carbon atoms, such as for example vinyl toluene, divinyl 
benzene, .alpha.-methyl styrene, tert.-butyl styrene, chlorostyrenes; 
vinyl esters of carboxylic acids containing from 2 to 6 carbon atoms, 
preferably vinyl acetate; vinyl pyridine, vinyl naphthalene, vinyl 
cyclohexane, acrylic acid and methacrylic acid and/or their esters 
(preferably vinyl, allyl and methallyl esters) containing from 1 to 4 
carbon atoms in the alcohol component, their amides and nitriles, maleic 
acid anhydride, semiester and diester containing from 1 to 4 carbon atoms 
in the alcohol component, semiamides and diamides or cyclic imides, such 
as N-methyl maleic imide or N-cyclohexyl maleic imide, allyl compounds 
such as allyl benzene and allyl esters, such as allyl acetate, phthalic 
acid diallyl ester, isophthalic acid diallyl ester, fumaric acid diallyl 
ester, allyl carbonates, diallyl carbonates, triallyl phosphate and 
triallyl cyanurate. 
The polyurethanes C (i) containing carboxyl groups essential to the present 
invention may have average molecular weights, as determined by membrane 
osmosis, in the range of from 2000 to 1,000,000 and preferably in the 
range of from 10,000 to 500,000. They may be produced in conventional 
manner by reacting a polyhydroxy compound having a molecular weight above 
600, optionally a compound containing two reactive hydrogen atoms and 
having a molecular weight below 600, and a polyisocyanate. In addition to 
polyester amides or polyacetates, preferred polyhydroxyl compounds having 
a molecular weight above 600 are, in particular, linear or predominantly 
linear polyesters of the type which can be obtained, for example by 
thermal condensation, from ethylene glycol, 1,2-propane diol, 1,3-propane 
diol, diethylene glycol, dipropylene glycol, 1,3-butane diol, 1,4-butane 
diol, neopentyl glycol, 2-ethyl-1,3-propane diol, 1,5-pentane diol, 
1,6-hexane diol, 2,2-bis-(hydroxymethyl)propionic acid and succinic acid, 
adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or 
phthalic acid. In addition to polyesters such as these, it is also 
possible to use hydroxyl polycarbonates, particularly those of 1,6-hexane 
diol and diaryl carbonates, and also esterification products of 
straight-chain hydroxyl alkane monocarboxylic acids containing at least 5 
carbon atoms or the corresponding lactone polymers or castor oil. The 
polyesters are produced under such conditions that at least most of their 
terminal groups consist of hydroxyl groups. Polyethers, such as propylene 
oxide or tetrahydrofuran polymers, or polythioethers, such as condensation 
products of thiodiglycol alone or with other diols, are also suitable. 
These products generally have an average molecular weight in the range of 
from about 600 to 5000 and preferably in the range of from 1000 to 2500. 
In addition to water or simple glycols, such as for example ethylene 
glycol, 1,3-propane diol, 1,4-butane diol, 1,5-pentane diol or 1,6-hexane 
diol, suitable compounds containing at least 2 isocyanate-reactive 
hydrogen atoms and having a molecular weight below 600 (chain extenders) 
are glycols containing urea, urethane, carbonamide or ester groups and 
also glycols containing tertiary nitrogen atoms. It is also possible to 
use glycols having aromatic ring systems, for example, 
1,5-naphthylene-3-dioxethyl ether or hydroquinone-.beta.-dioxethyl ether. 
Diamines such as o-dichlorobenzidine, 2,5-dichloro-p-phenylene diamine or 
3,3'-dichloro-4,4'-diaminodiphenyl methane, are also suitable as are, for 
example, hydrazine, amino alcohols, such as for example N-allyl 
ethanolamine, and amino or oxycarboxylic acids such as 
2,2-bis-(hydroxymethyl)-propionic acid. 
Preferred polyisocyanates are aliphatic, cycloaliphatic, araliphatic or 
aromatic diisocyanates containing from 4 to 30 carbon atoms such as, for 
example, 1,4-butane diisocyanate, 1,6-hexane diisocyanate, 1,4-cyclohexane 
diisocyanate, 1-methyl-2,4-diisocyanato cyclohexane, 
1-methyl-2,6-diisocyanato cyclohexane, 
1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane, 2,4- and 
2,6-diisocyanatotoluene, 4,4'-diphenyl methane diisocyanate, 4,4'-diphenyl 
propane diisocyanate, p-phenylene diisocyanate, 1,5-naphthylene 
diisocyanate and mixtures of these diisocyanates. It is particularly 
preferred to use 4,4'-diphenyl methane diisocyanate, 2,4- and 
2,6-diisocyanato toluene and mixtures thereof. 
The polyurethanes (C) containing carboxyl groups essential to the invention 
may be produced in conventional manner by reacting the polyhydroxyl 
compounds having a molecular weight above 600 with a diisocyanate in less 
than the quantity based on the terminal groups, adding the compound 
containing two reactive hydrogen atoms and having a molecular weight below 
600 and completing the reaction by adding more diisocyanate. It is also 
possible to react the polyhydroxyl compounds with an excess of 
diisocyanates over and above the quantity required for reaction with the 
terminal groups and to measure the quantity in which the compound having a 
molecular weight below 600 is used in such a way that there is an excess 
over and above the quantity based on the isocyanate groups still present. 
It is, of course, also possible to react the mixture of the polyhydroxyl 
compound having a molecular weight above 600 and the compound having a 
molecular weight below 600 with a deficit of diisocyanates. 
The carboxyl groups may be incorporated into the polyurethane resins 
according to the invention during their production either by using polyols 
containing carboxyl groups, even those having molecular weights above 600, 
for the reaction with diisocyanates or by subsequently acidifying the 
polyurethane free from NCO groups, for example with a dicarboxylic acid 
anhydride. It has proved to be particularly advantageous to use diols 
containing tertiary carboxyl groups because they do not react with NCO 
groups so that the quantity of carboxyl groups which can be incorporated 
may be calculated whereas other carboxyl groups react to some extent 
during the reaction with isocyanate. 
The polyurethane C containing carboxyl groups should have an acid number of 
at least 8 and at most 50. 
The polyurethanes C (i) containing at least one terminal radically 
polymerisable double bond per molecule which are essential to the 
invention may be produced in the same way as described above, but with the 
difference that diisocyanates are used in excess over and above the 
polyhydroxyl compounds, resulting in the formation of NCO-terminated 
polyurethanes of which the terminal NCO groups are subsequently reacted 
with radically polymerisable compounds which still contain at least one 
isocyanate-reactive hydrogen. 
Examples of these radically polymerisable compounds still containing at 
least one isocyanate-reactive hydrogen are, for example, hydroxyalkyl 
esters of acrylic or methacrylic or crotonic acid, such as for example 
hydroxyethyl acrylate or methacrylate, hydroxypropyl acrylate or 
methacrylate, hydroxyl-containing low molecular weight esters of maleic, 
fumaric, itaconic or citraconic acid, such as bis-ethylene or -propylene 
glycol fumarate or maleate, allyl alcohol or allyl ether alcohols, such as 
dimethylol propane monoallyl ether, trimethylol propane mono- or di-allyl 
ether, etc. 
The polyurethane C (iii) which contain both carboxyl groups corresponding 
to an acid number of at least 8 and also at least one terminal radically 
polymerisable double bond per molecule may be produced by a combination of 
the two processes described above, i.e. by producing an NCO-terminated, 
carboxyl-containing polyurethane of which the terminal groups are reacted 
in the manner described with a radically polymerisable compound which 
still contains at least one diisocyanate-reactive hydrogen. It is 
particularly preferred to use polyurethanes produced in this way because, 
in the production of resin mats, they are co-thickened with chemical 
thickeners, such as magnesium oxide, and can no longer be dissolved out 
after hardening as a result of copolymerisation. 
The polyurethanes C may be produced in the melt or in the form of a 
solution in B and may subsequently be mixed with the unsaturated polyester 
A or a solution thereof in B. These solutions are preferably clear or are 
only slightly clouded due to their structural viscosity. Where more 
serious incompatibility occurs, for example between two polyester and 
polyurethane solutions in styrene, separation may be eliminated by 
assimilating the esterification components of the unsaturated polyester A 
and the polyurethane C. If the unsaturated polyester A, for example, 
predominantly contains methyl-branched diols, the polyurethane resin 
should also predominantly contain methyl-branched diols. 
In order to protect the mixtures according to the invention against 
undesirable premature polymerisation, from 0.001 to 0.5 part by weight, 
based on 100 parts by weight of the sum of components A to C, of 
polymerisation inhibitors or antioxidants are added to components A and C, 
at the latest during dissolution in B. Preferred auxiliaries of this type 
are, for example, phenols and phenol derivatives, preferably sterically 
hindered phenols containing alkyl constituents with 1 to 6 carbon atoms in 
both o-positions to the phenolic hydroxy group, amines, preferably 
secondary aryl amines and their derivatives, quinones, copper salts of 
organic acids, and addition compounds of copper (I) halides with 
phosphites. Examples of such auxiliaries are 4,4'-bis-(2,6-di-tert.-butyl 
phenol), 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyl 
benzyl)-benzene, 4,4'-butylidene-bis-(6-tert.-butyl-m-cresol), 
3,5-di-tert.-butyl-4-hydroxyl benzyl phosphonic acid diethyl ester, 
N,N'-bis-(.beta.-naphthyl)-p-phenylene diamine, N,N'-bis-(1-methyl 
heptyl)-p-phenylene diamine, phenyl-.beta.-naphthyl amine, 
4,4'-bis-(.alpha.,.alpha.-dimethyl benzyl)-diphenyl amine, 
1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxy 
hydrocinnamoyl)-hexahydro-s-triazine, hydroquinone, p-benzoquinone, 
toluhydroquinone, p-tert.butyl pyrocatechol, chloranil, naphthoquinone, 
copper naphthenate, copper octoate, Cu(I)Cl/triphenyl phosphite, 
Cu(I)Cl/trimethyl phosphite, Cu(I)Cl/tris-chloroethyl phosphite, 
Cu(I)Cl/tripropyl phosphite, p-nitrosodimethyl aniline. Other preferred 
stabilisers are described in "Methoden der organischen Chemie" 
(Houben-Weyl), Fourth Edition, Vol. XIV/1, pages 433 to 452, Georg 
Thieme-Verlag, Stuttgart, 1961. One extremely suitable stabiliser is 
hydroquinone, for example in a concentration of from 0.01 to 0.05 part by 
weight, based on 100 parts by weight of the unsaturated polyester A. 
For producing moulding compositions from the mixtures according to the 
invention, the usual polymerisation initiators may be added to the 
mixtures in the usual quantities, preferably in quantities of from 0.5 to 
5 parts by weight, based on 100 parts by weight of the sum of components 
A, B and C. Suitable polymerisation initiators are, for example, diacyl 
peroxides, such as diacetyl peroxides, dibenzoyl peroxide, 
di-p-chlorobenzoyl peroxide, peroxy esters, such as tert.-butyl peroxy 
acetate, tert.-butyl peroxy benzoate, tert.-butyl peroctoate, dicyclohexyl 
peroxy dicarbonate or 2,5-dimethyl hexane-2,5-di-peroctoate, alkyl 
peroxides such as bis-(tert.-butyl peroxy butane), dicumyl peroxide, 
tert.-butyl cumyl peroxide, hydroperoxides, such as cumene hydroperoxide, 
tert.-butyl-hydroperoxide, cyclohexanone peroxide, methyl ethyl ketone 
hydroperoxide, perketals, ketone peroxides, such as acetylacetate peroxide 
or azoisobutyrodinitrile. 
The moulding compositions may contain as chemical thickeners oxides and/or 
hydroxides of metals belonging to the Second Main Group of the Periodic 
System, preferably magnesium and calcium, in quantities of from 0.1 to 10 
parts by weight and preferably in quantities of from 1.0 to 4.0 parts by 
weight, based on 100 parts by weight of the sum of components A, B and C. 
The above-mentioned chemical thickeners may also be partly replaced by 
zinc oxide. 
In addition, the moulding compositions may contain from 5 to 100 parts by 
weight and preferably from 10 to 40 parts by weight, based on 100 parts by 
weight of the sum of components A, B and C, of fibrous reinforcing 
materials. Suitable fibrous reinforcing materials are inorganic fibres, 
such as metal, asbestos, carbon and, in particular, glass fibres, and 
organic fibres such as, for example, cotton, polyamide, polyester, 
polyacrylonitrile or polycarbonate fibres. 
Suitable inorganic fillers, which are normally used in quantities from 50 
to 500 parts by weight, based on 100 parts by weight of the sum of 
components A, B and C, are for example chalk, talcum, powdered quartz and 
shale, kaolin, calc-spar, dolomite, mica, heavy spar, kieselguhr and 
diatomaceous earths. 
Standard additives which may also be used are, for example, organic and 
inorganic pigments, dyes, lubricants, and release agents, such as zinc 
stearate, thixotropic agents, UV absorbers, shrinkage-reducing additives, 
etc. 
The most rational way of producing the moulding compositions in the form of 
resin mats is intensively to mix mixtures A, B and C according to the 
invention with the other components, except for the reinforcing fibres, in 
dissolvers or on roll stands and to impregnate reinforcing fibres 
introduced in sheet form, including mats or woven fabrics, with this 
mixture. The surfaces of the resin mats thus produced may be protected on 
both sides by masking films. The films prevent the vinyl or vinylidene 
compounds B from evaporating and enable the mats to be rolled up and 
stored in compact form. After a thickening time, i.e. storage, for 1 to 2 
days at room temperature, the masking films may be removed and, after 
having been suitable cut to size, the resin mats may be converted into 
mouldings by pressing for about 0 to 5 minutes under a pressure of from 
about 2 to 16 mPa at a temperature of about 120.degree. to 160.degree. C., 
depending on the shape and size of the mouldings. If necessary, thickening 
may of course also be accelerated by storage at elevated temperature, for 
example 50.degree. C. 
Moulding compositions, also known as bulk moulding compounds, may be 
similarly produced. After a finely dispersed fibre-free mixture of the 
above mentioned type has been prepared by means of dissolvers or roll 
stands, it is mixed with fibres, generally glass fibres, in kneaders. In 
the interests of simplicity, all the components (including the fibres) are 
in many cases also mixed in kneaders. The moulding compositions are ready 
for moulding after storage for 1 to 2 days at room temperature. 
The mixtures according to the invention and the moulding compositions and 
mouldings produced therefrom are distinguished by the following 
advantages: 
(1) The mixtures according to the invention are preferably clear solutions 
and, hence, do not present any problems in regard to storage and 
processing. 
(2) The mixtures according to the invention have low viscosities which 
affords advantages in regard to the wetting of reinforcing fibres and 
fillers and provides for considerable latitude in the choice of the filler 
component. 
(3) Mixtures according to the invention with polyurethanes containing 
carboxyl groups can be chemically thickened with chemical thickeners 
without separation and give dry resin mats which can be processed without 
difficulty. 
(4) Mouldings based on the polyurethanes containing carboxyl groups show 
improved flexural strength and an almost threefold increase in impact 
strength over the base resins, even--surprisingly--in thickened form. In 
contrast to all other polyester resins, thickening with chemical 
thickeners produces virtually no reduction in impact strength. 
(5) Mouldings based on the polyurethanes containing at least one radically 
polymerisable double bond are distinguished by the same high resistance to 
solvents because the polyurethane is chemically incorporated. 
(6) Moulding compositions based on the mixtures according to the invention 
are distinguished by high dimensional stability under heat which is hardly 
affected by the added polyurethane.

The invention is illustrated by the following Examples and Comparison 
Examples in which the percentages quoted represent % by weight. 
EXAMPLES AND COMISON EXAMPLES 
Production of component A dissolved in B: 
Two unsaturated polyesters are produced by the melt condensation under 
nitrogen from the components listed below. Esterification is carried out 
at 210.degree. C. until the characteristics indicated are obtained. The 
polyesters are then dissolved in styrene at about 120.degree. C. The 
solutions are designated PE 1 and PE 2: 
______________________________________ 
PE 1 PE 2 
Polyester g g 
______________________________________ 
Fumaric acid -- 1160 
Maleic acid anhydride 
686 -- 
Isophthalic acid 498 -- 
1,2-propylene glycol 
456 -- 
Diethylene glycol 477 -- 
Bis-hydroxypropyl -- 3540 
bisphenol A 
Hydroquinone 0.42 0.87 
Characteristics of the 
solution in styrene: 
Styrene content (%): 
39 50 
Viscosity at 20.degree. C. (mPas): 
1100 700 
Acid number (mg KOH/g): 
18 10 
______________________________________ 
Production of component C dissolved in B: 
1. Production of a preliminary stage polyol (PEA) 
Adipic acid and ethylene glycol in a molar ratio of 1:1.03 are condensed by 
melt condensation under nitrogen at 210.degree. C. until an acid number of 
2 and an OH number of 63 are obtained. Corresponding to the OH number, the 
polyester obtained (PEA) has a calculated molecular weight of 1775. 
2. Production of polyurethane solutions: 
The quantities of the preliminary stage polyol PEA indicated in Table I are 
melted at 120.degree. C. without or together with dimethylol propionic 
acid and the indicated quantities of tolylene-2,4-diisocyanate are added 
dropwise to the melt with cooling under nitrogen in such a way that the 
temperature of the melt does not exceed 120.degree. C. After the dropwise 
addition, the melt is stirred for 15 minutes at 120.degree. C. and then 
dissolved, in the percentage quantity indicated, in styrene stabilised 
with 0.01% of benzoquinone. The solutions are cooled to 75.degree. C., 
0.03%, based on the polyurethane solutions, of tin dilaurate is stirred 
in, afer which the solutions are stirred for 3 hours at that temperature 
and the indicated quantities of hydroxypropyl methacrylate are added. 
After another 3 hours at 75.degree. C., the NCO content has fallen to 
below 0.01% and the solutions are cooled to room temperature. In the case 
of the Examples which do not contain any hydroxypropyl methacrylate, the 
last 3 hours' reaction time is left out. The solutions according to the 
invention are designated PU 1 to 4 and the associated comparison solutions 
by an additional V. Their characteristics are also shown in Table I. 
Production of the Examples and Comparison Examples according to the 
invention: 
The mixtures of the quantities by weight indicated in Table II of the 
polyurethane solutions PU 1 to 4 with the polyester solutions PE 1 and 2 
at room temperature represent the Examples and Comparison Examples. The 
polyurethane-free polyester solutions PE 1 and 2 are also used for 
comparison. 
2% by weight of benzoyl peroxide in the form of a 50% solution in dibutyl 
phthalate and 1.5% by weight of MgO are stirred into each of the mixtures 
according to the invention, after which the compositions are processed to 
form 4 mm thick plates. The compositions have thickened after ripening for 
3 days. They are hardened for 3 hours at 80.degree. C. and then tempered 
for another 15 hours at 100.degree. C. In each case, one other plate is 
produced without MgO. The plates obtained are used to produce standard 
small test bars for measuring impact strength (a.sub.n) and dimensional 
stability under heat according to Martens. The corresponding values are 
set out in Table II and distinctly show the advantageous influence of the 
polyurethane solutions according to the invention on the properties of the 
hardened system. 
TABLE I 
__________________________________________________________________________ 
Polyurethane solution 
PU 1 PU 1 V 
PU 2 PU 2 V 
PU 3 PU 4 
__________________________________________________________________________ 
PEA g (moles) 
1065(0.6) 
1775(1.0) 
1243(0.70) 
1509(0.85) 
750(0.65) 
1775(1.0) 
DMPS g (moles) 
53.6(0.4) 
-- 40.2(0.3) 
20(0.15) 
47(0.35) 
-- 
TDJ g (moles) 
170.5(0.98) 
170.5(0.98) 
182.7(1.05) 
182.7(1.05) 
182.7(1.05) 
182.7(1.05) 
HPMA g (moles) 
-- -- 15(0.15) 
15(0.15) 
15(0.15) 
15(0.15) 
Styrene (%) 
68 68 68 68 68 50 
Sn--DL 0.03 0.03 0.03 0.03 0.03 0.03 
Characteristics: 
Viscosity at 
1630 1530 1420 670 8000 thixotropic 
20.degree. C. (mPas) 
Acid number of 
5.4 -- 3.6 1.6 6 -- 
the solution 
Acid number of 
17 -- 12 5 19 -- 
the polyurethane 
__________________________________________________________________________ 
Abbreviations: 
PEA: Polyethylene glycol adipate 
DMPS: Dimethylol propionic acid = 2,2bis-(hydroxymethyl)-propionic acid 
TDJ: Tolylene2,4-diisocyanate 
HPMA: Hydroxypropyl methacrylate 
Sn--DL: Tin dilaurate 
TABLE II 
__________________________________________________________________________ 
Example No. 
1 I V 2 2 V 3 4 3 V 
4 V 
__________________________________________________________________________ 
PU solution 
PU 1 
PU 1 V 
PU 2 
PU 2 V 
PU 3 
PU 4 
-- -- 
PE 1: 62.3 g + 
37.7 g 
37.7 g 
37.7 g 
37.7 g 
37.7 g 
-- -- -- 
PE 2: 80.0 g + 
-- -- -- -- -- 20 g 
-- -- 
PE 1: -- -- -- -- -- -- 100 g 
-- 
PE 2: -- -- -- -- -- -- -- 100 g 
Viscosity at 20.degree. C. 
700 1020 710 450 780 1430 
1010 
750 g 
(mPas) 
Without MgO 
a.sub.n (KJ/m.sup.2) 
13 9 17 17 16 20 7 9 
Martens value (.degree.C.) 
69 65 69 68 64 95 86 115 
With 1.5% of MgO 
a.sub.n (KJ/m.sup.2) 
13 5 13 6 15 -- 5 -- 
Martens value (.degree.C.) 
74 65 68 65 62 -- 86 -- 
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a.sub.n = Impact strength