CA1055640A - Process for the preparation of polymerisable, stable, organic dispersions - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF POLYMERISABLE, STABLE, ORGANIC DISPERSIONS

Abstract of the Disclosure:

Process for the preparation of pourable stable dispersions of ethylene polymers in unsaturated polyester resins characterised in that the warmed solutions of the ethylene polymers and of the unsaturated polyesters in vinyl-aromatics are combined in a zone of high turbulence and stirred intensively at an elevated temperature until a pourable state of low viscosity has resulted.

Description

105~6~
The present application relates to a process for the preparation o~ stable dispersions of ethylene polymers, espe-cially of polyethylene, in organic media which consist of a non-solvent and a solvent for the ethylene polymers, wherein vinyl-aromatics are used as solvents and unsaturated poly-esters are used as non-solvents.
Unsaturated polyester resins which cure with little shrinkage are gaining increasing importance because of their technological advantages. For example, it is known from - 10 German Patent Specification 1,241,983 that moulding materials based on unsaturatçd polyesters, to which a certain propor-tion of e-thylene polymers has been added, can be cured wi-thout ~orming cracks and cavities. Furthermore, they give mou~d-ings having a perfect surface. However, there has hitherto been a lack of a process by which the said ethylene polymers can be distributed homogeneously in unsaturated polyester resins on a scale suitable for industrial manufacture.
A homogeneous fine distribution is achieved without problems if the polymer is soluble in a polyester/vinyl-aromatic system, as is the case, for example, ~or celluloseesters ~compare U.S. Patent Speci~ication 3,642,672).
High pressure polyethylene is insoluble in both vinyl-aromatics and unsaturated polyesters at room temperature;
whils-t it dissolves in vinyl-aromatics at elevated tempera-tures, it does not do so in unsaturated polyesters or in apolyester/vinyl-aromatic mixture. The direc-t use of granules as obtained from the preparation of high pressure polyethylene for the preparation of stable dispersions th~refore appears impossible.
It is known to introduce pul~erulent thermoplastics, such as polyethylene (French Patent Specification 1,148,285) or polypropylene (German O~fenlegungsschrift (German Published Le A 15 580 - 2 -1O~S6 40 Specification) 1,817,575 or German Auslegeschrift (German Published Specification) l,192,820) into unsaturated poly-ester resins. However, the use of finely divided7th~mop~stic powders presents problems, because of the associated hazar~
of dust explosion.
Further, it is known to prepare polyethylene disper-sions from granules in an aqueous system containing dispers-ing agent (German Offenlegungsschrift (German Published Speci-fication) 1,963,840). Aqueous dispersions are ~aturally unsuitable for use as thermoplastic additives ~or polyesterswhich cure with little shrinkage.
Further, it is known to prepare polyethylene powders by dissolving granules in a mixture of solvents and non-solvents and then distilling off the solvent (German Auslege-schrift (German Published Specification) 1,077,424 and German Offenlegungsschriften (German Published Specifications) 1,494,355 and 1,769,740)~ However, stable polyethylene dis-persions are not obtainable by this method.
It is admittedly possible to homogenise a mixture of 20 ethylene polymers and polyester resins, for example on a calendering roll, but this technique is not suitable for the preparation of stable suspensions free from fillers and there-fore demands immediate further conversion to filled products which are no longer capable of flow, such as, for example, filled glass fibre-reinforced resin mats. Accordingly, this process does not provide the possibility of separating, in time or space, the preparation of the resin from the conver-sion to filled materials.
Combining hot solutions of ethylene polymers and polyesters in vinyl-aromatics also does not provide the solution of the proble~s indicated Le A 15_580 - 3 -:~5564~

above since the ethylene polymers which precipitate as a gel coagulate and form a clearly visible sedimented phase. The coagulation can be delayed, but not prevented, by stirring and by the addition of dispersing agents.
It has nowbeenfourd,surprisingly, that pourable stable dispersions of ethylene polymers in systems which contain unsaturated polyesters and vinyl-aromatics can be produced by combining solutions of ethylene polymers and unsatura~ed polyesters in vinylaromaticsj in the presence of dispersin~
agents at 50 C - 120 C in a zone of high turbulence, with-drawing the resulting mixture from this zone and ke~ping it at 50 C - 120 C, with intensive stirring, until a pourable state of low viscosity has re~ul~ed For carrying out the process it is advantageous to combine the two solutions in a zone oP high turbulence under the simultaneous action of shear forces. On the other hand, it is found that during subsequent stirring at an elevated temperature shear forces and cavitation Porces must not be present or, if present 9 must be of negligible magnitude.
A zone of high turbulence, in the sense of the inven-tion, denotes generally a space where inten~e mixing occurs and through which at least 300 parts by volume of liquid pass per hour and per part by volume of the space. Turbulence zones,in which the liquid volume passing through per hour and per part by vol~me oP the turbulence zone is 1,200 to 5,400 parts by volume, that is to say in which the dwell time of the mixture in the turbulence zone is between approx. 6 seconds and less than one second,are preferred.
In general, known de~icesg for example conventional stirred kettles or, preferably, pumps equipped with rotors are used to produce a zone oP high -turbulence.
Le ~ 15 580 - 4 -_ .

~ss64al The specific mixing energy in an intensively stirred kettle is as a rule 10~1 to 10-3 Watt/cm3. It is higher immediately in the stirring vortex and suffices for forming dispersions with ethylene polymer contents of up to 25% by weight. For example, it is possible to employ a stirred kettle with a disc stirrer and flow breakers, in which the ratio of kettle diameter:stirring diameter should be between 1 : 0.9 to 1 : 0.2. When using such a stirred kettle, it is advisable to use a separate feed, which can be ac~ieved by introducing one compo~ent(the polyester/vinyl-aromatic solution) directly into the stirring vortex and -the other component (ethylene polymer/vinyl-aromatic solution) into the hollow shaft of the stirrer so that both components are first mixed ~ntensively and the vinyl-aromatic con-tent of -the gel is only lowered subsequently in a second step at a lower stirring intensity and increased temperature.
Pumps equipped with rotors are considerably more suit-able than conventional stirred kettles, above all because in these pumps the residence time in the zone of high turbulence is sharply limited. Special model~ specifically developed for high turbulence, the so-called centrifugal homogenising machines, are suitable for particularly high throughput;
their specific mixing energy is about 5 - 25 Wat-t/cm3. They thus permit particularly intensive mixing with a very short -residence time and are therefore used preferentiallyO
It has been found -that to achieve a high stability of the suspension it is particularly advisable that the mixtures which leave the zone of high turbulence should be recirculated into the turbulence zone so that the continuously freshly added polyester and ethylene polymer solutions ~re combined with already premixed product in the zone of high turbulence.
Le A 15 580 - 5 -It is also possible to mix the polyester solution wi-th the recirculating mixture be~ore entry into -the turbulence zone and to introduce the ethylene polymer solution in the turbu-lence zone. It is also possible to divide one stream, for example the stream of the e~hylene polymers, into several component streams and to introduce these at different points of the turbulence zone. In order to run with extremely high product throughputs, it is also possible to arrange several - turbulence zones in series.
The dispersions prepared in accordance with the pro-cess o~ the invention can contain 25 to 60% by weight o~
unsaturated polyesters. Vinyl-aromatics or mixtures o~
vinyl-aroma-tics and polymerisable vinyl or divinyl compounds and allyl compounds are used as solven-ts both ~or the ethylene polymer and ~or the polyester.
The solids contents of the dispersions prepared in accordance with the process o~ the invention are between l and 55% by weight, pre~erably between 5 and 25% by weight and in special cases between ll and 17% by weight. The solids con-tent denotes the content o~ ethylene polymer and dispersingagent in % by weight. The ethylene polymer is almost always dissolved in the ~inyl-aromatic at an elevated temperature.
The dispersing agent or the chosen dispersing agent combina-tions are in general also dissolved in the vinyl-aromatic together with the ethylene polymer, but can also be dissolved in the polyester or the polyester-vinyl-aromatic solution or be subsequently introduced into the ~inished dispersion.
The concentrations o~ the two solutions to be combined, o~
polyester, on the one hand, and ethylene polymer, on the o-ther, should be so chosen that the solutions are pourable and pump-able at the chosen working -temperature. Admittedly it would Le A 15 580 - 6 -. : . . . .:-.

105564~31 also be possible in principle to mix, for example, the undi-luted polyester with an ethylene polymer/vinyl-aromatic solu-tion in the manner described; naturally, the polyester would then however have to be heated to a temperature of about 140 -160C to be readily pumpable. Since, however, the ethylenepolymer solution must also in general be warmed to at least 70C to give a perfect solution, too high a mixing tempera-ture would result on combining the streams of material and hence the solubility of the ethylene polymer in -the system would be undesirably high, so that such a procedure would not prove succes~ul.
The temperature when bringing the two solutions to-gether is so chosen that a gel ~s first produced due 'to the spontaneously occurring precipitation of the ethylene polymer whilst the migration of the vinyl-aromatic from this gel into the polyester/vinyl-aromatic phase during stirring takes place as rapidly as pos-sible~ The preferred temperature is between 60 C and 90 C. The end of the dispersing process is recognisable from the fact that the viscosity of the stirred system and at the same time the ~tructural~viscosity properties, that is to say the non-Newtonian beh~viour, decline.
When the viscosity no longer changes, the process can be discontinued and the resulting dispersions of ethylene polymers in the polyestertvinylaromatic systems are consider~d to be stable.
It is surprising that this measure of subsequent stir~
ring at an elevated temperature leads to systems with fine distribution and low viscosity-It would be expected that freezing-in, achieved by rapid cooling, of the disperse states of distribution - once achieved by means of high energy -Le_A 15 ~30 - 7 -, . . , . , - . . . - ~ ...................................... . .
.. ... , , . . .~

:1055640 : would lead to high stabilities of the suspension and that at elevated temperatures a re-agglomeration would take place which would again annul the distribution once reached The stability of the dispersions is substantially assisted by the addition of dispersing agents.
Particularly effective dispersing agents are high molecular polymers soluble in copolymerisable vinyl-aroma-tics or in unsaturated polyes-ters or in a polyester/vinyl-aromatic mixture. Very particularly preferred dispersing agents are ethylene/vinyl acetate copolymers or polyvinyl acetates, preferably having a vinyl ace-tate content of 60 to 100% by weight, in special cases o:~ 65 to 75% by weight, and a Mooney viscosity of at least 15, preferably of 40 to 65 Mooney, measured according to DIN 53,523 (L-4).
Further suitable dispersing agents are poly-acrylic and polymethacrylic acid ester homopolymers and co-polymers which contain 1 to 24 C atoms ln the alcohol com- -ponent, such as, for example, polyacrylic acid decyl esters, or copolymers of ethylene, of up -to 60% by weight ethylene content, with acrylic acid esters or methacrylic acid esters which contain 1 to 24 C atoms in the alcohol component, or with vinyl esters of organic monocarboxylic acids or dicar-boxylic aci~ with 1 to 19 C atoms, or with their saponifica-tion products. Graft polymers with the said polymers as the graft substrate are also very good dispersing agents.
Further suitable dispersing agents are polyethers, such as polyethylene oxide, polypropylene oxide and copolymers of these two compounds, ethoxylated saturated and unsaturated fatty acids with 4 to 30, preferably with 6 to 19, C atoms, 3Q their esters which contain 1 to 24 C atoms in the alcohol com-ponent, their amides and nitriles, fatty alcohols with 1 to 30, Le A 15 580 - 8 -10556~0 preferably with 4 to 16 C atoms, or graft polymers with these polymers as the graft substrate, such as are ~escribed, for example, in German Auslegeschrift (German Published Specifica-tion) 1,137,554.
Suitable graft monomers are vinyl-aromatics, such as vinyltoluene, a-methylstyrene, tert.-butylstyrene and chloro-styrenes, but preferably unsubstituted styrene itself, and vinyl acetate, acrylic acid and methacrylic acid 9 their nit-riles and esters, of which the alcohol components can con-tain 1-18 C atoms, such as, for example, methyl methacrylate or ethyl acrylate, acrylonitrile and methacrylonitrile, maleic anhydride, and maleic acid half-esters and diesters with 1-30, pre~erabl~ ~ to 16, C atoms in the alcohol component. Of course, mixtures o~ the compounds listed can also be used both as graf-t subs-trates and as graft monomers.
Further suitable dispersing agents are cellulose derivatives such as methylcellulose, ethylhydr~xycellulose or cellulose esters, for e~ample cellulose acetate~ cellulose acetopropionate, cellulose acetobutyrate or nitrocellulose.
Sometimes, the introduc-tion of water, which can, ~or example, be dissolved in the dispersing agent, cannot be avoided en-tirely when preparing the dispersion. However, frequently this is not a disadvantage; on the con-trary, small amounts of water are frequently added deliberately since the stability of the dispersion can be improved by this measure. The finished synthetic resin system may contain up to 5% by weight of water; as a rule, however, the water con-tent is less than 1% by weight.
The dispersing agents are added in a concentration of 0.001 to 20% by weight, but preferably of 0.5 - 3% by weigh-t, relative to the finished dispersion.
Le A 15 580 - 9 -:`

1~5~640 In order to prevent undesirable premature polymerisa-tion of the polymerisable dispersion it is advisable to add 0.001 - 0.1% by weight of polymerisation inhibitors or anti-oxidants -to the dispersion already during preparation.
Examples of suitable auxiliaries of this nature are phenols and phenol derivatives, preferably sterically hindered phenols, which contain alkyl substituents with 1 - 6 C atoms in both o-positions relative to the phenolic hydroxyl group, amines, preferably secondary acrylamines and their derivatives, quinones, copper salts of organic acids and addition compounds of copper(I) halides with phosphites, such as, for example, 4,4'-bis-(2,6-di-tert.-butylphenol), 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-benzene, 4,4~-butylidene~bis-(6-tert.-butyl-m-cresol), 3,5-di--ter-t.-butyl-4-hydroxy-benzyl-phosphonic acid diethyl ester, N,N'-bis-(~-naph-thyl)-p-phenylénediamine, N,~'-bis-(l-methylheptyl)-p-phenylenediamine, phenyl-~-naphthylamine, 4,4'-bis-(~,~-di-methylbenzyl)-diphenylamine, 1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxy-hydrociunamoyl)-hexahydro-s-triazine, hydroquinone, p-benzoquinone, toluhydroquinone, p-tert.-butylpyrocatechol, chloranil, naphthoquinone, copper naphthenate, copper octoa-te, Cu(I)Cl/triphenyl phosphite, Cu(I)Cl/trimethyl phosphite, Cu(I)Cl/trischloroethyl phosphite, Cu(I)Cl/tripropyl phos-phite and p-nitrosodimethylaniline. Further suitable stabi lisers are described in "Methoden der organischen Chemie"
("Methods of Organic Chemistry") ~Houben-Weyl), 4-th edition, volume XIV/l, pages 433-452 and 756, Georg Thieme Verlag, ~tuttgart, 1961. p-~enzoquinone, in a concentration of 0.01 to 0.05% by weight, relative to the finished dispersion, is, for example, very suitable~
The ethylene polymers which can be used for the dis-Le A 15 580 - 10 -: `

l~S5~0 persing process according to the invention are prepared accor-ding to known tubular reactor or stirred reactor processesO
They are ethylene homopolymers and those ethylene copolymers which contain copolymerised comonomers in amounts o~ 0.1 -40% by weight, preferably of 0.1 - 20% by weight, and in - special cases 3 - 12% by weight. Pre~erred comonomers ared6-olefines with 3-8 C atoms, such as propylene, isobutene and butene-l. Vinyl esters of organic carboxylic acids with 1 to 19 C atoms, preferably vinyl acetate, vinyl halides such as vinyl chloride, acrylic acid and methacrylic acid, their esters which contain 1 to 8 C atoms in the alcohol component, -their nitriles and amides, such as, for example, me-thyl methacrylate, e-thyl acrylate, butyl acrylate, acrylonitrile, methacrylonitrile and optionally substituted acrylamide and methacrylamide are further also suitable.
The melt indices of the ethylene polymer, measured according to DIN 53,7~5 at 190C and 2.16 kp load range from material incapable of flow to values of up to 1,000; prefer-ably, polyethylene grades with melt indices between 0.1 and 20 are used.
Of course, not only high pressure polyethylenes but also grades of polyethylene prepared by low pressure processes or medium pressure processes, and also homopolyethylenes or ethylene copolymers prepared by special processes, can be dis-persed by the dispersing process according to the invention.
The following solvents, individually or as mixtures, are examples of vinyl-aromatics for the ethylene polymers:
styrene, its nuclear-substituted and side chain-substituted derivatives such as chlorostyrene, vinyltoluene, divinylben-zene, a-methylstyrene and tert.-butylstyrene, vinylpyridine, vinylnaphthalene and allylbenzene. As much as 80 %
Le A 15 580 - 11 -.

. - - . .. . . . .

~55~40 by weight of these vinyl-aromatics can be replaced,without dis-advantage, by other copolymerisable monomers, for example by vinyl cyclohexane, acrylic acid, methacrylic acid, their esters, amides and nitriles, maleic anhydride, half-esters and - 5 diesters, half-amides and diamides or cyclic imides such as N-methylmaleimide or N-cyclohexylmaleimide, and vinyl esters of organic carboxylic acids, such as, for example, vinyl acetate.
Further, it is possible to use allyl compounds such as, for example, allyl acetate, diallyl isophthalate, allyl carbon-ates and diallyl carbonates.
The unsaturated polyesters used in the dispersing pro-cess according to the invention are prepared in accordance with known processes by polycondensation of at least one a,~-ethylenically unsatura-ted dicarboxylic acid or its ester-forming derivatives, optionally mixed with up to 90 mol %, relative to the unsaturated acid component, of at least one saturated dicarboxylic acid or its ester-forming derivatives, with at least one dihydric alcohol. Examples of unsaturated dicarboxylic acids or their derivatives, to be used preferen-tially, are maleic acid or maleic anhydride and fumaric acid.
However, it is also possible to use mesaconic acid, citraconic acid, itaconic acid or chloromaleic acid. Examples of the saturated dicarboxylic acids, or their derivatives, which are used are phthalic acid or phthalic anhydride, isophthalic acid, terephthalic acid, hèxahydrophthalic acid or tetrahydro-phthalic acid or their anhydrides, endomethylenetetrahydro-phthalic acid or its anhydride, succinic acid or succinic anhydride and succinic acid esters and chlorides, adipic acid and sebacic acid. For the preparation of resins of low inflammability it is possible to use, for example, hexachloro-endomethylenetetrahydrophthalic acid (Het-acid), tetrachloro-Le A 15 580 - 12 _ : L~55640 phthalic acid or tetrabromophthalic acid. Flame repellency can also be achieved by adding halogen-containing compounds not co-condensed in the polyester, such as, for example 7 chloroparaf~in. Polyesters to be used preferentially con--tain maleic acid, of which up to 25 mol % can be replaced by phthalic acid or isophthalic acid. Dihydric alcohols which can be employed are ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,3-butanediol, l,4-butanediol, neopentyl glycol, 1,6-hexanediol, perhydrobisphenol and others. Ethylene glycol, 1,2-propane-diol, diethylene glycol and dipropylene glycol are used pre~erentially.
The polyesters to be used pre~erentia]ly mus-t have a high degree o~ crosslinking since they are moulded, and re-le~ed ~rom the mould, at high temperatures (140 - 160C) and must therefore have a correspondingly high heat distortion point.
The acid numbers of the polyesters should be be-tween 1 and 50, preferably between 5 and 25, the OH numbers should be between 10 and 100, pr~ferably between 20 and 50, and the molecular weight should b~ between approx. 500 and 10,000, pre~erably between approx. 700 and 3,000 (mea~ured by vapor-pressure osmosis in dioxane and in acetone).

Polymerisable stable organic dispersions prepared in accordance with the process of the invention consist of 25-60%
by weight of unsaturated polyesters, 1-35% by weight of ethy-lene polymers, 5-60% by weight of vinyl-aromatics and 0.001-20% by weight of dispersing agents.
The process of the invention is expl~ined in more detail in the text which follows, with the aid of two figures:
Le A 15 580 - 13 -:~SS641D
:.
Figure l shows an arrangement for carrying ou-t the - process. A polyester/vinyl-aromatic solution from the heated s-toc~ kettle (2) is introduced continuously into ~ mixing devicelv~ the gear pump (3) and the valve (4), and at the same time an ethylene polymer/vinyl-aromatic solution is introduced continuously into the mixing device l from the heated stock kettle (5) via a gear pump (6) and the heat exchanger (7). In the mixing device (l), a gel ~ith pro-nounced structural viscosity is produced from the pourable solution containing the vinyl-aromatic, the temperature of the gel being above the calculated temperature of the mix-ture, because of the high energy of mixing introduced. The gel leaves the mixing device via valve (~) and passes into the heated s-tirred kettle (9) 9 the capacity of which is many times the free mixing volume of the mixing device. The stirred kettle (9) can of course also be constructed as a stirred cascade (10) which is heated, so -that the instal-lation can be run continuously with high product throughputsO
Figure 2 shows a particularly advantageously employed variant of the process.
A polyester/vinyl-aromatic solution from the heated stock kettle (2) is introduced continuously into a mixlng device (l) via the gear pump (3) and the valve (4) and at the same time an ethylene polymer/vinyl-aromatic solution is introduced continuously into the mixing device from the heated stock kettle (5) via a gear pump (6) and the heat exchanger (7), In the mixing device, a gel of pronounced structural viscosity is produced from the pourable solutions containing vinyl-aromatic. This gel, after leaving the mixing device via the heat exchanger (8) and a gear pump (9), which has about lO times the pumping capacity of the pumps (3) and (6), Le A_15 580 - 14 -lQ5564~

is recirculated via pipeline (10) into -the infeed zone of the mixing device via valve (11), so that three streams are now ~ed -to the mixing device, o~ which two streams can, as shown in Figure 2, be cor,lbined before reaching -the mixing zone.
A part-s-tream of the product stream which issues from the mixing zone via pump (9) is fed via valve (12) to a heated stirred ket-tle (13). The stirred volurne of this stirred kettle is again many times the mixing volume of the mixing zone.
After the s-tirred kettle, the material can be cooled in stages (14).
In order -to explain the process ~urther, the prepara-tion of a stable dlspersion o~ high pressure polye-thylene in a solution o~ an unsaturated polyester in styrene will be des-cribed by way o~ an example. The percentages are % by weight.
The polyester A used in the examples which follow is a condensation product of 31% by weight of 1,2-propanediol, 17% by weight of di-1,2-propanediol (= 4-oxa-hepta-1,2,6,7-tetraol), 40% by weight of maleic anhydride and 12% by weight of phthalic anhydride, having an acid number o~ 30, which was prepared by heating the mi~ture to 210C for 10 hours. The resulting polyester was dissolved in styrene, together with O.OZ% by weight of hydroquinone, to give a 650io strength by weight solution having a dynamic viscosity of 1,500 cP, measured according to DIN 53,015 at 20C (= polyester solu-tion A).
The polyethylene B used was a high pressùre homopoly-ethylene having a melt index of 6.1~ measured according to DIN 53,735 and the ethylene/vinyl acetate copolymer C used ~as a high pressure polyethylene having a vinyl aceta-te con--tent of 8.5% by weight and a melt index o~ 5.1, measured Le A 15_580 - 15 -1~55~

according to DIN 537735.
Exa~le 1-~rocess accordin~ to Fil~re 1.
188 kg/hour of the polyester solutio~ A and 134 kg/hour of a 28.6% (b~ weight) strength solution of polyethylene B in styrene, which contains 4.85% by weight of an ethylene/vinyl acetate copolymer of 70% by weight vinyl acetate content and having a Mooney value of 50, measured according to DIN 53,523 (L-4), are fed to the mixing device in accordance with Figure 1~
The temperature of both solutions is 78C before entering the mixing device, which opera-tes with a mixing energy of 25 Watt/cm3.
After leaving the mixing zone via valve (7), the temperature o~ the mixed product is 88C. The -tempera-ture of the product is raised to 90C in the heated stirred ket-tle (8). After the stirred kettle has been filled, it is stirred for a further 45 minutes. The product can then be cooled, for example whilst stirring, by switching off the heating of the stirred kettle, but can also be filled in-to con-tainers whils-t hot, and be passed on to its further use or be stored.
A subsequent stirred kettle cascade is frequently more sult-able ~or a continuous production sequence, provided -the con-di-tion that the mixture be stirred at 90C for a further per-iod, which is about 45 minutes in the present example, is observed. A suspension having a dynamic viscosity of 792 Cp (25C), measured according to DIN 53,015, is ~btained.
Example 2:
Process accordin~ to Figure 2.
80 kg/hour of the polyes-ter solution A and 53.5 kg/hour of a 31.2% (by weight)strength solution of the ethylene/vinyl ace-tate copolymer C in styrene, which also con-tains 1.25% by Le A 15 580 - 16 -. . ,:: :

1~55~

weight of an ethylene/vinyl acetate copolymer with 75% by weight of vinyl acetate incorporated therein (Mooney value 54, measured according to DIN 53,523, L-4) are fed in accordance with Figure 2 to the mixing device, which operates wi-th a mix-ing energy of 20 Watt/cm3. The temperature of the ethylene/
vinyl acetate copolymer solution is 80C and the tempe1atUre of the polyester solution is 20C 1.2 m3/hour are recir-culated, as an internal circuit, via the pump (12); the temperature of this internal circuit is kept at 80C by means of the heat exchanger (8), which in the present example is cooled by brine at -10C. Since, in this method of produc-tion according to Figure 2, the amount of produc-t freshly supplied to the mixing zone per hour is considerably reduced compared to the procedure according to Figure 1, -the mixing energy supplied to the product, and hence also the rise in temperature of the product in the mixing zone, is,of course,sub-stantially greater.For this internal circuit, maintained via the pump (11), 120 l/hour of mixed product is withdrawn via valve (12) and fed to the heated stirred kettle(13)in which the product is warmed -to 90C and stirred for a further 15 minutes at this temperature, A suspension having a dynamic viscosity of 680 centipoise (25C), measured in accordance with DIN 53, 015, is obtained.
Example 3:
Process accordin~ to Fi~ure 2. ~ -80 kg/hour of the polyester solution A and 54 k~/hour of a 28%(by weight)streng-th ~olution of the eth~lene/~inyl acetate co-polymer C in styrene, which also contains 2.7~ by weight of an ethylene/vinyl acetate copolymer with 70~ by weight of vinyl acetate incorporated therein (Mooney viscosity: 50 - 52 Mooney, measured accor~ing to DIN 53,523, L-4) a:re fed in Le A 15 580 - 17 -:

~OSS6~L0 accordance with Figure 2 to the mixing device, which operates with a mixing energy of 25 Watt/cm3. The temperature of the ethylene polymer solution is 80C ancl that of the polyester solution is 25Cr 1.2 m3/hour are recirculated as an in-ter-nal circuit via the pump (12); the temperature of this inter-nal circuit is kept at 80C by means of the heat exchanger (8), which in this example is cooled with brine at -10C. 120 1/
hour of mixed product are withdrawn from the internal circuit via the valve (12) and fed to the heated stirred kettle (13) in which the product is stirred for 30 minutes at 65C and 30 minutes at 50C. During this time, 1% by weight of a graft product of styrene on polyethylene oxide is dissolved in the suspension and furthermo~e 0.3% by weigh-t of wa-ter is added.
Preparation of the dispersing agent: 1,600 g of styrene, in which 16 g of benzoylperoxide are dissolved, are added drop-wise over the course of 2 hours to 1 kg of polyethylene oxide of molecular weight about 1,500 at 160 - 170C. After -the dropwise addition, the mixture is stirred for 3 hours at 170C
and 4 hours at 180C and is then cooled. A suspension having a dynamic viscosity of 750 centipoise, measured according to DIN 53,015, is obtained.
Example L~:
Using a dispersion prepared according to the proce-dure of Example 1:
A resin mat of dark brown colour was prepared in accordance with the following recipe: I00 parts by weight of dispersion (containing 12 parts by weight of high pressure polyethylene B, 2.0 parts by weight of an ethylene/vinyl acetate copolymer containing 70% by weight of vinyl acetate (Mooney viscosity: 52 Mooney, measured according to DIN 53 523 (L-4), 28 parts by weight of styrene and 60 par-ts by Le A 15 580 - 18 -_ __ ~S~640 weight of polyester solution A), 100 parts by weight of cal-cium carbonate filler (Durcal ~ 5 fro~ Omya), 4 parts by weight of zinc stearate, 0.75 part by weight of 95% s-trength (by weight)tert.butyl perbenzoate,3.35 parts by weight of Bayer13CB
red iron oxide, 1.65 parts by weight of Bayer F 318 black iron oxide, 1.50 parts by weight of magnesium oxide (Marmag ~ from Merck, Darmstadt) and 0.01 part by weight of p-benzoquinone.
A glass fibre mat (Vetrotex ~ M 612) was impregnated with this mix; the finished resin mat had a glass content of 26-28%by weight. The resin mat was matured for 7 days at 25 C.
After this time, i-t had a dry surface and the polyethylene film could be pulled off easily.
Tablets and sheetq having a rip and A pro~ectin~ p~ece were pro-duced from this resin mat in metal moulds at 140C. For the tablets, the press pressure was 30 kp/cm2, and for the sheet it was 150 kp/cm2. The pressings produced from the resin mat had a surface of medium gloss and barely visible sink marks where the material was thicker.
They had a homogeneous deep brown colour. The linear shrink-age was 0.05%. A ælightly marke~ glass fibre structure was recognisable on the surface of the rnouldings.
Example 5:
A resin mat was prepared, in accordance wi-th the recipe indicated in Example 4, from a dispersion according to Example

2. The content of dispersing agent (ethylene/vinyl acetate copolymer containing 70% by weight of vinyl acetate) was 0.5 part by weight per 100 parts by weight of dispersion.
After maturing for 7 days at 25C, the polyethylene film could very easily be pulled off the dry surface of the ~0 resin mat. Tablets and sheets were pressed as indi-cated in Example 4. The pressings had a very Le A 15 580 - 19 -1~556401 glossy surface of homogeneous deep brown colour without any glass fibre structure and showed no sink marks where the material was thicker, The linear shrinkage was less than 0.01%.
- 5 Example 6:
A resin mat was prepared from a dispersion according to Example ~, in accordance with the recipe indicated in Example 4. The disp~rsing agent content of the dispersion was 1.1% by weight of an ethylene/vinyl acetate copolymer containing 70% by weight o~ vinyl aceta-te and having a Mooney viscosity of 52, measured according to DIN 53,523, L-4, and 1% by weigh-t o~ a gra~t product o~ styrene on polyethy-lene oxide, containing about 67% by weight o~ styrene. A~ter a maturing time o~ 7 days at 25C, -the polyethylene ~ilm could very easily be pulled of~ the dry sur~ace o~ the resin mat.
Pressings were produced as indicated in Example 4~ The finished mouldings had a homogeneous deep brown colour and a very glossy sur~ace without visible glass ~ibre structure, and showed no sink marks where -the material was thicker.
The linear shrinkage was less than 0.01%.

Le A 15 580 - 20 -.

... . , ...................... ~ . . . .~.
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Claims (3)

CLAIMS:

1. Process for the preparation of pourable stable dis-persions of ethylene polymers in systems which contain unsatu-rated polyesters and vinyl-aromatics 3 characterised in that the solutions of the ethylene polymers and of -the unsaturated polyesters in vinyl-aromatics, warmed to 50 - 120°C, are com-bined in the presence of dispersing agents in a zone of high turbulence, and the resulting mixture is withdrawn from this zone and stirred intensively at 50 - 120° C until a pourable state of low viscosity has resulted.

2. Process according to Claim 1, characterised in that the dispersing agents used are polyvinyl acetates or ethylene/
vinyl acetate copolymers having a vinyl acetate content of 60 - 100% by weight and a Mooney viscosity of at least 1 Mooney.

3. Polymerisable stable dispersions which have been pre-pared by a process according to Claim 1.