Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1056~83
O.Z~ 30,881
MOLDING MATERIALS BASED ON UNSATURATED POLYESTER RESINS
The present invention relates to molding materials based on
unsaturated polyester resins which contain alkaline earth metal
oxides or hydroxidesg inhibitors and, optionally, conventional fillers
and reinforcing agents and other additives, and wherein the unsaturated
polyester consists of a mixture of an amorphous polyester and a
crystalline polyester. These molding materials can, in particular,
be used for the manufacture Or paper laminates.
Molding materials and press-forming materials based on unsaturated
polyester resins usually contain, in accordance with their envisaged
use, unsaturated polye3ters, monomeric vinyl compounds copolymerizable
therewith, polymerization initiators and inhibitors, pulverulent
fillers, and glass fibers or sheet-like glass fiber structures. To
manufacture impregnated reactive paper laminates based on unsaturated
polyester resins, rillers are generally not added, so as to obtain,
after heat-curing under pressure, transparent binders or coatings
through which the paper decoration is visible.
To obtain non-tacky molding materials and press-forming materials,
as well as semi-rinished goods, exhibiting optimum flow under the
required curing conditions, small amounts of finely particulate
alkaline earth metal oxide or hydroxide are in most cases admixed
with the polyester molding materials. This causes thickening through
salification of the carboxyl end groups of the unsaturated poly-
ester, and complex formation. The pot life or available processing
timè is from one to several hours whilst the time required to reach
the ultimate viscosity (thickening time) is up to several weeks. How-
ever, this makes economical processing difficult since, in con-
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~056083 Z . 3a 881
tinuous production, substantial numbers of moldings must be stored,which represents a disadvantage~
For rapid processing of the materials - which is, eOg., essential
when using them in conveyor belt installations - the time required
for thickening up should be as short as possible (with a pot life of
about one hour) whilst the viscosity of the molding material or press-
forming material in its final s~ate (at room temperature) should be
high.
Numerous additives which accelerate the increase in viscosity
Of unsaturated polyester resins containing magnesium oxide have been
disclosed; most of these are polar substances. For example, a low
concentration of water (German Patent 1,198,551), as well as compound
which liberate water (German Published Application 2,221,108) reduce
the thickening time, but give a low final viscosity, so that the
resulting products are frequently tacky (cf. F.B~Alvey, J. Polym.
Sci~ 9 (1971)~ 2~233-2~245)o Furthermore, the addition of dicarboxylic
acid anhydrides, eOg. hexahydrophthalic anhydride (U.S. Patent
3~465~061) ~ of carboxylic acids (German Printed Application 1~694~821
and U.S. Patent 3~465~061) ~ of phosphorous acid esters or their
halides, and of sulfonic acids and sulfonic acid halides (British
Patent 1~058~460) has been proposed. The effect of these thickening
accelerators is, however, inadequate, in most cases, to achieve rapid
ripening which should require only a few minutes. If brief thickening
times are achieved by adding a larger amount of accelerator, the
resulting viscosity of the molding material or press-forming material
i9 relatively low, and the materials remain tacky so that the
release films can only be pulled off with difficulty, if at all,
particularly when using thin unfilled resin layers, e.g. for the
manufacture of reactive paper laminates. It is true that the tacki-
ness can be reduced by adding fillers but this destroys the requisitetransparency of the cured molding materialsO
Other methods of thickening, e.g. the use of half-ester salts
of trivalent metals (German Printed Application 1,060,590) give pot
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lives of only a few ~inutes, and therefore these systems are hardlysuitable for conventional methods of manufacture of molding materials.
The fact that phosphorus halides are excellent thickening
accelerators is disclosed, inter alia, in ~erman Patent Application
P 23 11 395.3 published on May 12, 1974. By use of these halides,
tack-free, very viscous molding materials can be obtained very quickly;
however, the additives disclosed do not have a favorable effect on the
flow during hot-pressing, as the viscosity of the materials increases,
whilst such flow is important to give optimum surrace characteristics
Or the moldings.
The use Or a release film is desirable to reduce the evaporation
Or styrene - conventionally used as a monomer - from the resin layer
and prevent the stacked paper laminates sticking to~ether on storage.
Films of polyethylene, polyamide or polyester and polyvinyl alcohol
have proved satisfactory.
From a commercial point o~ view, polyethylene films would be of
particular interest, but since they swell and are permeable to
styrene, an~ therefore give a wavy surface of the molding material
ir thickening takes place slowly, they cannot be used for certain
applications, e.~. with reactive paper laminates. The other release
films mentioned above are more expensive and cannot be pulled Orr
conventionally thickened unrilled molding materials without difficulty;
however, in contrast to polyethylene rilms, they do prevent major
losses Or styrene and virtually do not swell in this monomer.
It is an object of the present invention to provide quick-
ripening molding materials which are suitable for use with these
styrene-impermeable films.
It is a rurther object of the present invention to provide
molding materials based on unsaturated polyester resins which, whilst
having an adequate pot li~e, thicken more quickly than conventional
materials and give a very high viscosity, without an adverse effect
on the rlow of the molding materials durin~ processin~
1~56083
We have found that this ob~ect is achieved by unsaturated
polyester molding materials, curable in the presence of conventional
polymerization initiators, and based on a mixture of
(a) from 15 to 80 per cent by weight, based on the total amount of
the components (a) to ~e), of at least one unsaturated poly-
ester, having an acid number of from 5 to 100 and a mean
molecular weight of from 50a to 10 000,
(b) from 5 to 60 per cent by weight, based on the mixture of
components (a) and (b), of at least one copolymerizable
olefinic compound
(c) from 1 to 5 per cent by weight, based on the mixture of
components (a) and (b), of an alXaline earth metal oxide
and/or hydroxide
~d) from O.OOS to 0.1 per cent by weight, based on the mixture
of components (a) and (b), of an inhibitor selected from the
group consisting of hydroquinones, quinones, nitrobenzenes,
aromatic amines and salts of N-nitroso-N-cyclohexyl-hydro-
xylamines and
(e) assistants and additives,
the improvement which comprises: using as said unsaturated poly-
ester (a) from 10 to 95% by weight of at least one amorphous
unsaturated polyester ~al) which is soluble in component (b)
at room temperature and from 90 to 5% by weight of at least one
crystalline unsaturated polyester ~a2) which has a solubility
of less than 30% by weight in styrene at 23C or is insoluble
in component ~b) or in the mixture of (b) and (al) at room
temperature.
The present invention also relates to the use of these
unsaturated polyester molding materials for covering or coating
a sheetlike base of organic or inorganic fibers, and to the
~manufacture o laminates therefrom.
The molding materials of the invention are cured at
room temperature or above, if appropriate in the presence of
thîc ~ ng accelerators~
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lOS6083
The molding materials of the invention specifically have
the advantage, over conventional unsaturated polyester resin m~lding
materials, that they are tack-free and dimensionally stable at room
temperature and may be cured to give transparent molded products.
The following are details relating to the components of
the molding materials to be used in the process of the invention:
(a) Suitable unsaturated polyesters are the conventional polyconden-
sation products of polybasic, especially dibasic, carboxylic acids
and their esterifiable derivatives, which are linked by ester
bonds to polyhydric, especially dihydric, alcohols and optionally
additionally contain radicals of mono~asic carboxylic acids and/or
radicals of monohydric alcohols and/or radicals of hydroxycarboxylic
acids wherein at least some of the radicals must contain ethylenic
copolymerizable groups.
The polyhydric, especially dihydric, alcohols are in
general reacted in stoichiometric, or approximately stoichiometric,
amounts with polybasic, especially dibasic carboxylic acids or
their condensable derivatives.
(al) Suitable amorphous unsaturated polyesters are the
conventional unsaturated polyesterQ, soluble in monomer (b), which
are manufactured by polycondensation of a,~-unsaturated dicarboxylic
acids or their anhydrides, optionally in combination with mono-
carboxylic acids and/or polycarboxylic acids, and monoalcohols
and/or polyalcohols, which serve as modifiers; examples of
a,~-unsaturated dicarboxylic acids which may be used are fumaric
acid, maleic acid, mesaconic acid, itaconic acid, methyleneglutaric
acid, citraconic acid and the like or their esters or anhydrides.
Maleic acid, maleic anhydride and fumaric acid are preferred.
Examples of suitable monocarboxylic acids and/or
polycarboxylic acids which act as modifiers are ethylhexanoic
acid, fatty aci~ds, methacrylic acid, benzoic acid, o-phthalic acid,
isophthalic acid, tetrahydrophthalic acid, tetrachlorophthalic acid,
èndomethylenetetrachlorophthalic acid, hexachloroendomethylenetetra-
hydrophthalic acid, succinic acid, glutaric acid, adipic acid and
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1056083
pimelic acid.
Suitable alcohol components are diols, e.g. 1,2-propane-
diol, 1,3-butanediol, 1,3-propanediol, ethylene glycol, diethylene
glycol,-polyethylene glycol, 1,6-hexanediol, neopentylglycol,
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` ~056083 o. z . 30,881
propa~e monoallylether, 1,4-butanediol, vinylglycol and dipropylene
glycol, with propanediol, diethylene glycol and dipropylene glycol
being preferred. Minor amounts of polyalcohols, e.g. glycerol, tri-
methylolpropane and pentaerythritol, and of monoalcohols, e.g.
2-ethylhexanol or ratty alcohols, may be used at the same time.
Epoxides, e.g. propylene oxide, can also be used to manufacture the
unsaturated polyesters.
The polycondensation can be carried out either in the melt, or
azeotropically using an inert entraining agent, e.g. xylene, or in
solution. Ir an epoxide is also used, it may be desirable to use a
catalyst.
The polyesters are in general manufactured so as to give acid
numbèrs of from 5 to 100 and mean molecular weights of advantageously
from 1,000 to 4,000. It is also possible to use mixtures of such
polyesters, and mixtures with diallyl ester prepolymers, e.g. obtained
e.g. obtained from diallyl phthalate.
Amorphous unsaturated polyesters soluble in the monomer (b) are
to be under~tood a~ those of which at least 60 per cent by weight
di~olves in styrene at 23C.
(a2) Crystalline unsaturated polyesters, sparingly soluble or
insoluble in component (b) or in the mixture o~ (b) and (al), at room
temperature, which may be used accordin~ to the invention are such
unsaturated polye~ters as are disclosed, e.g., in British Patent
644,287, U.S. Patent 3,510,457 and German Printed Application
1,544,673. A characteristic feature of the synthesis of these
unsaturated polyesters is that symmetrical diols, e.g. 1,4-butanediol,
1,3-propanediol, 1,6-hexanediol, neopentyl glycol and hydroxyp~valic
acid neopentyl glycol ester, and predominantly symmetrical dicarboxy-
lic acids, e.g. fumaric acid, terephthalic acid and the like, are used.
The melting range of these crystalline unsaturated polyesters is in
general from 40 to 180C, preferably from 80 to 120C, depending on
their structure. Mixtures of such crystalline unsaturated polyesters,
the~mol~cular r '
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O.Z. 30,881
weight of which is from 300 to 10,000, advantageously from 700 to
4,000, may also be employed. They are preferably employed as
crystallite suspensions of low viscosity, which are suitably obtained
by slow cooling Or the hot, agitated solution of the crystallizing
polyester (a2) and the amorphous unsaturated polyester (a1) in a
copolymerizable vinyl monomer. It is also possible first to cool a
hot solution of the crystallizing polyester (a2) in a vinyl monomer
and then to combine the resulting crystallite suspension with a
solution of an amorphous polyester (a1) in the monomeric vinyl com-
pound.
If the crystallite suspension obtained has too high a v~scosity,
the latter can be lowered to the desired value by adding further
vinyl monomer or adding a solution of an amorphous unsaturated poly-
èster in the vinyl monomer at room temperature.
Crystalline unsaturated polyesters which are sparingly soluble
or insoluble in the monomer or in the solution of component (a1) in
the monomer are to be understood as those which have a solubility of
<30 per cent by wei~ht in styrene at 23C and are at least 70%
crystalline.
According to the invention, the unsaturated polyester (a)
comprises preferably from 30 to 80, per cent by weight of the
soluble, amorphous unsaturated polyester (al) and preferably
from 15 to 60, per cent by weight of the crystalline unsaturated
polyester (a2) which is sparingly soluble or insoluble at room
temperature.
The molding materials according to the invention in general con-
tain from 15 to 80, preferably from 20 to 70, per cent by weight of
unsaturated polyester (a) based on the total amount of the com-
ponents (a) to (ej.
(b) Suitable copolymerizable olefinic monomeric compounds are
the vinyl and allyl compounds conventionally used to manu~acture un-
saturated polyester molding materials, e.g. styrene, substituted
st renes, such as p-chlorostyrene, o~-methylstyrene or vinyltoluene,
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0,Z. 30,881
esters of acrylic and methacrylic acid ~ith alcohols containing 1 to
18 carbon atoms, e.g. methyl methacrylate, butyl acrylate, ethyl-
hexyl acrylate, hydroxypropyl acrylate and dicyclopentadienyl
acrylate, acrylic and methacrylic acid amides, allyl esters, e.g.
diallyl phthalate, and vinyl ester, e.g. vinyl ethylhexanoate and
vinyl pivalate, and others. In addition, minor amounts of poly-
olefinic compounds, e.g. divinylbenzene or butanediol diacrylate~
may al80 be present.
Mixtures of the above olefinic monomers may aiso be used. The
preferred components (b) are styrene, vinyltoluene, ~-methylstyrene
and diallyl phthalate. The molding materials according to the
invention in general contain preferably from 15 to 40, per cent
by weight of component (b), based on the mixture of components (a)
and (b).
(C) Suitable alkaline earth metal oxides are calcium oxide,
calcium hydroxide and, preferably, magnesium oxide, and mixtures of
the8e oxides or hydroxide5. These may also be partially replaced by
zinC oxide.
In general, the molding material according to the invention
contains preferably from 1.5 to 2.5, per cent by weight of
component (C)~ ba8ed on the mixture of components (a) and (b).
(d) Inhibitors Which may be used are the conventional products,
e.~. hydroquinone, tert.-butylpyrocatechol, p-benzoquinone, chloranil9
nitrobenzenes, SUCh as m-dinitrobenzene, aromatic amines, such a8
thiodiphenyl~mine or 8alt8 Or N-nitroso-N-cyclohexyl-hydroxylamine8,
as well a~ their mixtures. The molding materials contain preferably
from 0.01 to 0.05, per cent by weight of the inhibitors, ~ased on
the components (a) and (b)
(e) In addition, in most cases conventional fillers, pigments,
reinforcing agents and, if appropriate, inert solvents, polymeri-
zation accelerators and/or other assistants usually employed in pro-
cessing polyester molding materials are added to the molding
m~ ~ lals employed in the process according to the invention.
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lOS6083 o.z. 30,881
Examples of suitable fillers are conventional finely pulverulent
or granular inorganic or organic fillers, such as cement, chalk,
kaolin, finely disperse silica, quartz, talcum, kieselguhr, finely
particulate crosslinked organic polymers, sa~rdust, wood shavings and
the likeO
Reinforcing agents which may be used are inorganic or organic
fibers or sheet-like materials produced therefrom, e.g. non-wovens,
mats or woven fabrics, e.g. made of glass, asbestos, cellulose and
synthetic organic high polymers.
From 5 to 200, preferably from 50 to 150, per cent by weight of
the fillers and reinforcing agents, based on the components (a) to
(d), may be used.
Further assistants which may optionally be used at the same
time are: inert solvents, e.g. ketones, esters and hydrocarbons, in
amounts of from O to 10 per cent by weight based on the component (a),
additives which reduce shrinkage, e.g. thermoplastic polymers, such
as polyethylene, poly~tyrene, styrene copolymers, polyvinyl chloride,
polyvinyl acetate and vinyl acetate copolymers, or polyacrylates or
polymethacrylate~, in amounts of up to about 30 per cent by weight,
based on the components (a) and (b), and also polymerization accele-
rators, e.g. cobalt octoate or aromatic amines, pigments, e.g.
titanium dioxide, chromium oxide or organic pigments, mold release
agents, e.g. phosphoric acid esters and metal salts of higher fatty
acids, e.g. Zn stearate or Ca stearate, in amounts of from 0.05% to
5% based on the components (a) and (b), and thickening accelerators,
e.g. PC13 or POC13, in amounts of about 0.02 to 0.2 per cent by
weight~ based on the unsaturated polyester (a) and the monomeric vinyl
compound.
Polymerization initiators which may be used for the polyester
molding materials of the invention are those which are as stable as
possible at room temperature but at elevated temperatures give free
radicals which initiate the polymerization, e.g. peroxides, such as
benzoyl peroxide, dicumyl peroxide, di-tert.-butyl peroxide, tert.-
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` 1~56083 o, z, 30,881
butyl perbenzoate or their mixtures, azo compounds, e.g. azodiiso-
butyronitrile, or or~anic compounds which decompose into free radicals
through scission of a C-C bond, and others.
The amount of catalyst is from 0.5 to 6 per cent by weight,
advantageously from 1 to 3 per cent by weight.
The mixing of the individual components, to form the molding
materials of the invention, may be carried out in conventional
mixing equipment. A suitable method is to add all the additives
successively, except for the alkaline earth metal oxides and the
thickening accelerator, and to admix these latter materials only
shortly before processing the resin batch.
The molding materials of the invention may be cured at elevated
temperatures under pressure to give moldings havin~ particularly
good surface glo9s. In addition to their rapid thickening it is above
all the achievable viscosity levels, namely values of ~rom 109 to
101 mPa.s which are significant. These make it possible to use poly-
èster, polyvinyl alcohol or polyamide release rilms which, in con-
trast to polyethylene film, are very resistant to diffusion of
styrene and are not swollen by styrene. After pulling off these films,
the surface of the thickened molding material is tack-free and smooth
even ir no fillers have been added, so that transparent molded pro-
ducts can be manufactured. The polyester molding materials of the
invention may be used to produce surface coatings of curable paper
laminates, or to manuracture tran~parent moldings.
The materials Or the invention may al~o be used to manufacture
prepregs and press-rorming materials. In these cases, their main
advantage is that ripening takes place more quickly, that high vis-
cosities are achieved and that at the same time they exhibit good
flow during hot-pressing. As a result, moldin~ materials of reduced
tackiness are obtained, which can be cured, even after extended
storage, to give moldings of improved surface gloss. Similar advan-
tages are found if the method of the invention is applied to the manu-
facture and processing of molding materials of low shrinkage which
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1 0 S 6l08 3 -Z. 30,~81
additionally contain thermoplastic polymers and in general have a
great tendency, after extended storage, to ~orm a deposit on the mold
during hot-pressing, which has an adverse effect on the surface gloas
of the molding.
Unless stated otherwise, parts and percentages in the examples
are by weight.
Unsaturated polyester resins
Resin A is a 65~ strength solution in styrene, stabilized with 0.01~ of
hydroquinone, of an unsaturated polyester of maleic acid, o-phthalic
acid and 1,2-propylene glycol in the molar ratio of 2:1:3.15. The
acid number of the polyester is 50.
Resin B i8 a 65% strength solution in styrene, stabilized with 0001%
of hydroquinone, of an unsaturated polyester of maleic acid and 1,2-
propylene glycol in the molar ratio of 1:1. The acid number of the
polye~ter i9 18.
Resin C is a 64% strength solution in styrene, stabilized with 0.01%
of hydroquinone, of an unsaturated polyester of maleic acid, tetra-
hydrophthalic acid and diethylene glycol in the molar ratio of
1:0.5:1.5. The acid number of the resin is 30.
Polyester D is a crystalline unsaturated polyester of fumaric acid,
adipic a¢id and 1,4-butanediol in the molar ratio of 4:1:5. The poly-
ester has an acid number of 20 and melts at 112C (Kr~mer-Sarnow-
Nagel method).
Resin E is a 72% strength solution in ~tyrene, stabilized with 0.01%
of hydroquinone, o~ an unsaturated polyester Or maleic acid, 1,2-pro-
pylene glycol and dipropylene glycol in the molar ratio of 1:0.78:0.33.
The polyester has an acid number of 38 and contains 0.460 equivalent
of polymerizable double bonds per 100 g (double bond value).
To prepare the crystallite suspension F a mixture of 485 parts
of polyester resin A, 650 parts of polyester resin B, 4~4 partæ of
crystalline polyester D and 380 parts of styrene, to which 0.135 part
of hydroquinone has been added, i~ heated to 110C under an inert gas,
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10S60~3 o. z. 30,881
whilst stirring, and the resulting solution is then slowly cooled to
room temperature~ The suspension has a viscosity of 1,000 mPas.
The crystallite suspension G was prepared analogously to sus-
.
pension F from a mixture of 460 parts of crystalline polyester D,
460 parts of unsaturated polyester resin B, 358 parts of styrene and
00128 part of hydroquinone. The viscosity (at 23C) was 552 mPa.s.
EXAMPLE
A crystallite suspension which had a viscocity (at 23C) of
2.5 x 106 mPa.s wasprepared by cooling a solution, at 110C, of
2,100 parts of resin A and 1,200 parts of resin D to 50C whilst
stirring and then continuing the cooling, to room temperature, with-
out istirring.
To test the thickened mixture in comparison with resin A, 100
parts Or this crystallite suspension were diluted with 30 parts of
styrene, which lowered the viscosity to 980 mPa.s,2 parts of magnesium
oxide and 1 drop Or phosphorus oxychloride were stirred in and the
mixture was stored for 24 hours at 23C.
A stiff mass of viscosity (at 25C) 2.0 x 107 mpa.s~measured on
the Konsistometer from Haake, Berlin) was obtained.
Under the same ripening conditions, resin A, after addition of
30% of styrene, gave a viscosity (at 25C) of 5.9 x 105 mPa.s.
EXAMPLE 2
A crystallite suspension was prepared analogously to Example 1
from 2,100 parts of resin C and 1,200 parts Or resin D. 10 parts of
styrene, 2 parts of magnesium oxide and 1 drop of phosphorus oxy-
chloride were added to 100 parts of this viscous mixture, which was
then ripened for 3 hours at 50C. Thereafter the viscosity (at 25C)
was 1.7 x 109 mPa.s(measured on the Konsi~tometer from Haake, Berlin).
If resin C was thickened under exactly the same conditions after
addition of 10~ of styrene, a mass having a viscosity of only
3.5 x 108 mPa.s formed.
EXAM~LE 3 --
.
30 ~ ~ A solution is prepared from 700 parts of resin B, 400 parts of
~A. - 12 -
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` 1~56083 o. z. 30,881
crystalline polyester D and 330 parts of styrene at 1~0C under an
inert gas; when cooled to room temperature whilst stirring, it gives
a suspension of viscosity (at 23C) 408 mPa.s.
To test the thickening properties, a torsional rheometer (Plasto-
graph type PL S3 from Brabender, Duisburg) was used. 58 g Or a mix-
ture Or 100 parts o~ the above suspension and 2 parts of magnesium
oxide were kneaded at 78C (kneader temperature) and 130 rpm under
conditions such that no styrene was able to escape. After 20 minutes,
a torque of 1.06 x 1o~2Nm was measured.
In contrast, resin B, after dilution with 30% Or styrene, did
not react under the set conditions. In a further experiment, resin B
was kneaded without added styrene. Here again no thickening was
observable (torque ~ 0 Nm).
EXAMPLE 4
In order to observe the efrect Or crystalline unsaturated poly-
e~ters in unsaturated polyester resins thickened with magnesium
oxide, the following experiments were carried out in a torsional
rheometer (Plasti-Corder, type PL V 151, rrom Brabender, Duisburg).
70 g Or thickened unsaturated polyester resins A and ~ - see
the Table - were treated in the kneader at 100C and 130 rpm, the
apparatus being covered to avoid losse~ Or styrene, and the constant
torque which was set up was determined. Mixtures of these thickened
resins with polyester D (in the weight ratio of 7:4) were then tested
under the same experimental conditions ror the torque set up. Each
Of the products was taken out arter 8 minutes, and a part thereo~ was
stored tightly sealed in aluminum foil for 20 hours at 23C, after
which its viscosity was determined (using a Konsistometer).
TABLE
Flow o~ thickened unsaturated polye~ter resins
Thickened resin. Polyester D Torque Viscosity (at 23C) arter
(g) (g) (Nm) 20 hours (mPas)
70 Aaj 05.70 x 10 2 2.5 x 108
, 04.90 x 10 2 1.2 x 108
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1056~83 o.z. 30,881
44~5 A 25.5 1.63 x 10 2 2.1 x 109
4405 B 25.5 1.84 x 10 2 1.6 x 109
(a) Resin A was thickened with 2% of MgO and 1% of a 19% strength
solution of hydrogen chloride in dimethylformamide, by keeping the
mixture at 23C for 2 hours and t~en at 80C for 2 hours. ~he resin
was additionally stabilized with 0.01% of p-quinone.
(b) Resin B was thickened as described under a) but using only
1.5% of magnesium oxide.
This shows that as a result of the addition of a crystalline
polyester, unsaturated polyester resins thickened with alkaline earth
metal oxides show better flow when warm, but at the same time show an
increased viscosity at room temperature.
EXAMPLE 5
In order to test the effect of crystalline polyesters on the
manufacture and procèssing of unsaturated polyester resin molding
materials, a glass mat was impregnated with a mixture of 12.4 parts
of su~pension F, 47.6 parts of resin E, 40 parts of a 33% strcngth
solution in styrene of a toughened polystyrene, 60 parts of (R)Hydro-
carb filler, 90 parts of a chalk filler ((R) Omya BL R 2), 3 parts
of Ca stearate, 3 parts of green chromium oxide, 3 parts Or 50%
strength tert.-butyl perbenzoate and 1.5 parts of magnesium oxide,
and ripened for 3 days at 23C, between films.
After removing the films, the mat was pressed in a polished
steel mold for 5 minutes at 145C under 7.36 N/mm2 and the plate-
shaped molding, containing about 30% of glass, was released from the
mold whilst hot. The cured test specimen showed a high surface gloss.
If the crystallite suspen~ion in the above molding material
recipe~ was replaced by resin E, the molding produced under otherwise
identical conditions showed a markedly diminished surface gloss.
EXAMPLE 6
To manufacture a molding material which can be granulated and can
be cured by hot-pressing to give a transparent molded product, a
solution of 800 parts of polyester D, 300 parts of styrene and 310
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parts Or resin C was prepared under an in~rt gas at 110C. After
cooling to 50C, 100 parts of styrene, 30 parts of magnesium oxide,
3705 parts of dicumyl peroxide and 1.5 parts Or phosphorus trichloride
were added and the mixture was kept at 50C for 3 hours and then
cooled to room temperature. The hard mass could be pulverized and
stored as a powder without tendency to block. A part of this powder
was pressed for 5 minutes at 140C under a pressure of 0.98 N/mm2,
giving a cured transparent molded product.
EXAMPLE 7
A rapid ripening experiment with unfilled unsaturated polyester
resins to give tack-free films, using magnesium oxide, was carried
out with suspension F. For this purpose, 100 parts of suspension F,
1.33 parts Or magnesium oxide and 1.0 part of a 10% strength solution
Or phosphorus trichloride~ in dimethyl phthalate were mixed and a
part Or this mixture, in the form Or a thin layer (about 1 mm) was
kept at 80C between styrene-impermeable films for 10 minutes. After
cooling to room temperature, it was possible to pull Orr the films
without the material Or the thickened mixture adhering thereto. The
viscosity (at 23C) Or the molding materia~ was 8.4 x 107 mPa.s
(using a Konsistometer).
2Q A part Or the mixture was stored at 23 C and the change in vis-
cosity was followed. The results in the Table show that the pot life
is at least 3 hours.
Time (ho~rsj 1 2 3 4
_
Vi8co~ity (at 23C), mPas 1,3701,720 1,903 10,430
EXAMPLE 8
To test whether the covering rilms can be pulled Orr more easily,
arter rapid ripening Or thin films Or molding material, ir in place
o~ the conventional unsaturated polyester resins crystallite sus-
pensions are reacted with MgO at elevated temperatures, 100 parts of
resin B and, separately, 100 parts Or the suspension G prepared there-
30 from, were mixed with 1.33 parts of magnesium oxide and 0.06 part of
~ - 15 -
~. . ; . .. .. . . . .
1056083 o.z. 30,881
phosphorus oxychloride and the mixture was kept between cellophane
and PVC films for 5 minutes at 80C and then cooled. The films could
only be pulled off satisfactorily from the molding material based
on suspension G, whilst the molding material based on resin B was
still excessively tackyO In the latter case, thickening times of
about 40 minutes at 80C were needed to permit perfect detachment
of the covering films~ Similar results were obtained when the experi-
ments were carried out with other films (e.g. of polyamide, polyvinyl
alcohol, polyethylene or polyester) or with aluminum foil.
- 16 -
.
