Thermoplastic polyester moulding masses with high tenacity.

0001The invention relates to thermoplastic molding compositions with improved impact strength at low temperatures made from thermoplastic polyesters, in particular from polyalkylene terephthalates, and grafted, at least partially crosslinked diene rubbers and / or acrylate rubbers with a bimodal distribution of the rubber particle diameters.

0002Thermoplastic polyesters, especially polyethylene terephthalate, polybutylene terephthalate and some copolyesters, have become increasingly important due to their outstanding technological properties such as rigidity, hardness, abrasion resistance, dynamic and thermal resilience, as well as their quick processability. A disadvantage of these polyesters is their unsatisfactory toughness.

0003There are a number of proposals to improve the toughness of the thermoplastic polyester by admixing other polymers. There have been proposed (co) polystyrenes (DE-OS 1 694 173, DE-OS 1 961 226, DE-OS 2 035 390, DE-OS 2 248 242), polyolefins (EP-A 13 941), grafted acrylate rubbers ( DE-PS 2 444 584, DE-OS 2 726 256) and grafted diene rubbers (DE-PS 2 348 377). In addition, grafted acrylate rubbers and grafted diene rubbers have been proposed which have a very specific graft structure or which have been prepared by certain processes (EP-A 22 216, EP-A 50 265, EP-A 50 262, EP-A 64 207 , DE-OS 3 114 772).

0004The proposed molding compositions generally have improved toughness. However, it has been shown that they are not always fully satisfactory for important applications, for example in the motor vehicle sector, where large deformation forces can act in the event of a collision, for example on the body, the bumpers and spoilers, the steering wheel and the steering wheel column. There are special requirements for this, even for low temperatures down to -20 ° C, sometimes down to -30 ° C.

0005The invention therefore relates to thermoplastic molding compositions<ul id="ul0001" list-style="none"><li>A) 65-97, preferably 70-95, in particular 75-90,% by weight (based on A + B) of thermoplastic polyester and</li><li>B) 3-35, preferably 5-30, in particular 10-25,% by weight (based on A + B) of graft product of at least one vinyl monomer from the series styrene, acrylonitrile, methyl methacrylate on particulate, at least partially crosslinked diene rubbers and / or Alkyl acrylate rubbers with average rubber particle diameters from 0.05 to 1 μm and with a rubber content of the graft products from 60 to 85, preferably 65 to 80, in particular 70 to 75,% by weight, characterized, that graft product B is based on the following rubbers:<ul id="ul0002" list-style="none"><li>a) 20 to 80, preferably 30 to 70, in particular 35 to 60 wt .-% (based on the sum a + b) of a rubber latex with a particle diameter d₅₀ from 0.05 to 0.19, preferably 0.08 to 0.15 µm, and</li><li>b) 80 to 20, preferably 70 to 30, in particular 65 to 40% by weight (based on the sum a + b) of a rubber latex with a particle diameter d₅₀ from 0.2 to 1, preferably 0.25 to 0.8, in particular 0.3 to 0.6, µm, with the proviso that<ul id="ul0003" list-style="none"><li>1) d₅₀ (b) is greater than d by a factor of 1.5 to 8, preferably 2.7 to 5, in particular 3 to 4.5₅₀ (a),</li><li>2) the quotient Q = (i.e.₅₀-d₁₀) / d₅₀ of the individual rubbers in each case at most 2, preferably at most 1.8, in particular at most 0.8, and</li><li>3) the difference d₁₀ (b) - d₉₀ (a) 0.01 to -0.10, preferably 0 to -0.08, in particular 0 to 0.05.</li></ul></li></ul></li></ul>

0006The weights of the rubber latices are based on solids. To produce the graft product B, either a rubber latex corresponding to a) and a rubber latex corresponding to b) can be mixed in the stated ratio and the vinyl monomers graft-polymerized onto this mixture or the vinyl monomers separated from one another on a rubber latex according to a) and on a rubber latex according to b) graft polymerize and the two graft products (either as latices with subsequent co-precipitation or as mix existing solids). The second method is preferred.

0007These molding compositions are more suitable than known ones for the above-mentioned applications, but nevertheless have no significant disadvantages.

0008It is essential to use at least partially cross-linked diene rubbers and / or acrylate rubbers with rubber particle sizes of 0.05 to 1 µm, which have a "bimodal" particle diameter distribution.

0009This means that by combining certain coarse-particle rubbers with certain fine-particle rubbers in the form of graft polymers B, molding compositions according to the invention have substantially improved properties;

0010for this purpose, the rubber particle size distribution used to produce component B must be bimodal and should have two distinct maxima. However, in order to observe the effect associated with these specific particle size distributions, it is necessary to start from rubbers whose particle size distribution obeys certain parameters: These include a critical breadth of the distribution curve (expressed by the quotient Q), a critical distance between the distribution curve maxima (expressed by the Difference d₅₀ (b) - d₅₀ (a)) and a critical overlap of the distribution curves (expressed by the difference d₁₀ (^b) - ^d₉₀ (a)).

0011The effect according to the invention is all the more surprising since finely divided rubber only moderately increases the impact strength of thermoplastic polyesters and coarse-particle rubber leads to a continuous decrease in the toughness of the molding composition as the temperature drops.

0012The graft products B comprise graft polymers with rubber-elastic properties which are obtained by grafting vinyl monomers from the series styrene, acrylonitrile, methyl methacrylate onto particulate, at least partially crosslinked diene rubbers and / or alkyl acrylate rubbers.

0013Preferred graft monomers are methyl methacrylate and mixtures of styrene and methyl methacrylate or styrene and acrylonitrile.

0014Diene rubbers are particulate, crosslinked homopolymers and / or copolymers of conjugated C.₄-C₆-Serve. Preferred diene is 1,3-butadiene. In addition to the diene residues, the diene copolymers can contain up to 30% by weight, based on the copolymer, of residues of other ethylenically unsaturated monomers, such as styrene, acrylonitrile, esters of acrylic or methacrylic acid with monohydric alcohols having 1 to 4 carbon atoms, such as Contain methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate.

0015The production of the diene rubber graft base and the _Pfrog polymers is known and is described, for example, in "Methods of Organic Chemistry" (Houben-Weyl), vol. 14/1, Georg Thieme Verlag, Stuttgart 1961, pp. 393-406, and in Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Vol. 19, Verlag Chemie 1981, pp. 279 to 284.

0016Alkyl acrylate rubbers are particulate, crosslinked alkyl acrylate polymers which are obtained by polymerizing esters from acrylic acid and monohydric alcohols having 1 to 8 carbon atoms. The polymers can also be copolymers of acrylic acid esters with up to 40% by weight of other vinyl monomers, such as styrene, acrylonitrile, methyl methacrylate, vinyl esters, vinyl ethers.

0017The alkyl acrylate rubbers are crosslinked, for example by polymerizing in polyfunctional, crosslinking, copolymerizable olefinically unsaturated comonomers. Monomers with more than one polymerizable double bond can be copolymerized for crosslinking. Preferred examples of crosslinking monomers are esters of unsaturated monohydric alcohols with 3 to 12 C atoms or saturated polyols with 2 to 4 OH groups and 2 to 20 C atoms, such as Ethylene glycol dimethacrylate, allyl methacrylate; polyunsaturated heterocyclic compounds such as trivinyl and triallyl cyanurate and isocyanurate; Tris-acryloyl-s-triazines; in particular trialkyl cyanurate; polyfunctional vinyl compounds such as di- and trivinylbenzenes; but also triallyl phosphate and diallyl phthalate.

0018Preferred crosslinking monomers are allyl methacrylate, ethylene glycol dimethacrylate, diallyl phthalate and heterocyclic compounds which have at least three ethylenically unsaturated groups.

0019Particularly preferred crosslinking monomers are the cyclic monomers triallyl cyanurate, triallyl isocyanurate, trivinyl cyanurate, tris-acryloylhexahydro-s-triazine and triallylbenzenes.

0020The amount of the crosslinking monomers is preferably 0.02 to 5, in particular 0.05 to 2,% by weight, based on the rubber graft base.

0021In the case of cyclic, crosslinking monomers with at least three ethylenically unsaturated groups, it is advantageous not to use more than 1% by weight, based on the rubber graft base.

0022_AAcrylic acrylate rubbers can also be multi-shell products which contain a cross-linked diene rubber made from one or more conjugated dienes, such as polybutadiene, or a copolymer of a conjugated diene with an ethylenically unsaturated monomer, such as styrene and / or acrylonitrile, as the core and polymerized acrylate monomer as a shell.

0023The proportion of the polydiene core in such multi-layer rubbers can be 0.1 to 80, preferably 10 to 50% by weight. Shell (s) and core can be partially cross-linked or highly cross-linked independently.

0024The diene rubbers and the alkyl acylate rubbers lie as particles with an average diameter d₅₀ in the range of 0.05 to 1 µm and are at least partially cross-linked. They have gel contents ≥50, preferably ≥80, in particular ≥90% by weight.

0025The mean particle diameter d can be determined by means of ultracentrifuge measurements (W. Scholtan, H. Lange, Kolloid. Z. and Z. Polymer 250 (1972), 782-796) or by means of electron microscopy and subsequent particle counting (G. Kämpf, H. Schuster, Angew. Macromolecular Chemistry 14 (1970), 111-129).

0026If the particle distributions are determined by means of electron microscopy and subsequent particle counting, then number average (and not weight average) are obtained. However, the number averages determined in this way must then be converted into weight averages so that they can be compared with the values ​​given here₁₀, d_50' dg₀ are comparable. This conversion is carried out, for example, according to W. Scholtan and H. Lange and provides well-matched values ​​for both methods. Furthermore, reference is made to DIN 53 206, where conversions of particle size distributions are defined.

0027The mean particle sizes given in this application are in all cases the weight-average particle size, as determined by means of an analytical ultracentrifuge according to the method of W. Scholtan and H. Lange, Kolloid-Z. and z.-Polymer 250 (1972), pages 782 to 796. The ultracentrifuge measurement provides the integral mass distribution of the particle diameter of a sample. From this it can be seen what percentage by weight of the particles have a diameter equal to or smaller than a certain size. The average particle diameter, which is also called d₅₀The value of the integral mass distribution is defined as the particle diameter at which 50 percent by weight of the particles have an equal or smaller diameter than the diameter that corresponds to the d₅₀Value corresponds. To characterize the width of the particle size distribution of the rubber particles, in addition to the d₅₀-Value (average particle diameter) resulting from the integral mass distribution d₁₀-and dg_OValues ​​used. The d₁₀- or d₉₀-Values ​​of the integral mass distribution are in accordance with the d₅₀-Value defined with the difference that they are based on 10 to 90 wt .-% of the particles. The quotient<maths id="math0001" num=""><img file="EP0131202A1_D0001.tif" /></maths>represents a measure of the distribution width of the particle size.

0028The difference d₁₀ (b) - d₉₀ (a) then represents a measure of the overlap of the curves: If the difference is positive, there is no or only a slight curve overlap; if the difference is negative, there is a curve overlap, the extent of which is described by the size of the negative value.

0029As already mentioned, the number average distribution of the rubber particles can also be determined and then converted into weight average. The microscopic counting method according to G. Kämpf et al. the more precise, the more particles are counted; normally at least 10⁴ Particles are measured, which then provide a particle size number average distribution curve after statistical evaluation. For example, the particle size classes can be chosen so large that 90% of the particles are divided into no fewer than 20 classes.

0030It remains to be added that the rubber particles are present in the molding compositions in the grafted state; one could thus assume that the grafting changed the rubber particle size compared to the rubber particles present in the rubber latices (for the production of B). However, it has been shown that the grafting and the amount of graft sheaths according to the characteristics described here have practically no influence on the size of the rubber particles, so that, within the scope of comparability, the distribution curves determined on molding compositions can be compared with the distribution curves determined on latex.

0031The gel content of the diene rubbers is determined at 25 ° C in toluene, the gel content of the alkyl acrylate rubbers at 25 ° C in demethylformamide (M. Hoffmann, H. Krömer, R. Kuhn, Polymeranalytik I and II, Georg Thieme Verlag Stuttgart 1977).

0032Preferred grafted alkyl acrylate rubbers are those which<ul id="ul0004" list-style="none"><li>a) are crosslinked with cyclic trifunctional comonomers, such as triallyl cyanurate or triallyl isocyanurate (described in DE-OS 3 039 114);</li><li>b) contain a polybutadiene core (described in DE-OS 3 039 115);</li><li>c) were prepared in the absence of suspending agents (described in DE-OS 3 117 052).</li></ul>

0033Which rubber content is the cheapest for producing the molding compositions according to the invention depends, inter alia, on the particular rubber particle diameter and on the graft density.

0034Rubbers with the particle diameters according to the invention can be obtained by emulsion polymerization of suitable monomers. In the emulsion polymerization processes known for this purpose, the latex particle diameters can be set by selecting the process conditions, for example by the type and concentration of the emulsifier, particle agglomeration, electrolytes, temperature, monomer / polymer concentration.

0035In the preparation of the graft products B by graft copolymerization, which is usually carried out in the presence of free radical initiators, for example water-soluble initiators, emulsifiers or complexing agents / graft activators, and regulators, in addition to the actual graft copolymer to a certain extent, free polymers or copolymers of the Graft-forming graft monomers. The amount of this ungrafted polymer can be determined by the degree of grafting or the graft yield can be characterized. This depends, among other things, on the polymerization conditions, the composition of the rubber graft base, the size of the particles to be grafted and the amount of grafted rubber graft base.

0036The molding compositions according to the invention have optimal properties if the amount of free (co) polymer of the graft monomers does not exceed certain limits. This upper limit is generally 15% by weight, preferably 10% by weight, in particular 7% by weight, based on the molding composition of A + B. The Staudinger index [η-] of these free (Co ) Polymers should be ≤0.6 dl / g, preferably ≤0.4 dl / g, measured in dimethylformamide at 25 ° C.

0037To achieve certain technological properties, it can be advantageous to also prepare the polymers of the graft monomers separately and to add them to the molding compositions during the preparation.

0038However, the procedure can also be such that a separately prepared polymer of the graft monomers is present during the graft copolymerization. It is also possible, if appropriate, to separate excess polymer of the graft monomers from the graft products B. Which route is followed depends on the chosen polymerization process, the type of rubber graft base, the type and amount of the graft monomers and the desired technological properties of the molding compositions.

0039The person skilled in the art can carry out and control the graft polymerization of the graft monomers onto the rubber particles in such a way that the graft product compositions required according to the invention are formed and, at the same time, the graft monomer polymer contents which may be required are generated.

0040Such special polymers, consisting of graft polymers in a mixture with suitable graft monomer polymers, can then be used directly for the production of the molding compositions. In such cases, the graft polymer is of course largely chemically identical to the graft monomer. However, the invention does not rule out the fact that the graft monomer polymers are of a chemically different nature than the graft monomers used for the grafting. For example, a polymethyl methacrylate can be used as the graft monomer polymer and, at the same time, a styrene-acrylonitrile-grafted rubber can be used as graft product B. Such combinations can optionally be associated with particular advantages in terms of application technology.

0041The "bimodal" graft products B can be produced by various processes. They can be prepared by grafting a dispersion of fine-particle rubber particles (corresponding to a) with monomers, then mixing this graft polymer emulsion with a separately produced graft-polymer emulsion of coarse-particle rubber particles and then working up this mixture.

0042It is also possible to mix the rubber particle dispersions (latices) and graft-polymerize the graft monomers onto this mixture, in particular in an aqueous emulsion using systems which form free radicals, and then work up in a known manner.

0043However, finely divided graft products and coarsely divided graft products can also be prepared separately, mixed and then worked up this mixture.

0044According to the preferred process, the mixtures of rubber particle dispersions of the bimodal particle distribution according to the invention are grafted with graft monomers, in particular in an aqueous emulsion by means of systems which form free radicals, and then worked up in the known manner.

0045However, finely divided graft products and coarse-particle graft products can also be prepared separately and mixed in amounts corresponding to the composition a / b according to the invention with the thermoplastic polyesters to produce the molding compositions according to the invention.

0046In the processes of separate grafting and joint processing of the graft product on the one hand and in the separate production of finely divided and coarse-particle graft product on the other hand, it is also possible to use graft products with different structures of the fine-particle and coarse-particle components.

0047These methods are therefore preferred.

0048Thermoplastic polyesters A in the sense of the invention are condensation products of aromatic dicarboxylic acids (or their derivatives) and aliphatic, cycloaliphatic, araliphatic or aromatic diols and mixtures of these reaction products.

0049Thermoplastic polyester A from aromatic dicarboxylic acids and aromatic diols are preferably condensation products from terephthalic acid and isophthalic acid (or their derivatives) and diphenols of the general formula:<chemistry id="chem0001" num="0001"><img file="EP0131202A1_D0002.tif" /></chemistry>with R = -CH₂- -0- <chemistry id="chem0002" num="0002"><img file="EP0131202A1_D0003.tif" /></chemistry><chemistry id="chem0003" num="0003"><img file="EP0131202A1_D0004.tif" /></chemistry>R¹, R², R³, R^{4 =} Alkyl group with 1-4 C atoms, H.

0050The preferred diphenol is 2,2-bis (4-hydroxyphenyl) propa_n.

0051Thermoplastic polyester A from aromatic dicarboxylic acids or their reactive derivatives (eg dimethyl esters or anhydrides) and aliphatic, cycloaliphatic or araliphatic diols and mixtures of these reaction products are preferably polyalkylene terephthalates.

0052Preferred polyalkylene terephthalates can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols with 2 to 10 carbon atoms by known methods (Kunststoff-Handbuch, Vol. VIII, pp. 695 ff, Carl Hanser Verlag, Munich 1973).

0053Preferred polyalkylene terephthalates contain at least 80, preferably at least 90 mol%, based on the dicarboxylic acid component, terephthalic acid residues and at least 80, preferably at least 90 mol%, based on the diol component, ethylene glycol and / or 1,4-butanediol residues. In addition to terephthalic acid residues, they can contain up to 20 mol% of residues of other aromatic dicarboxylic acids with 8 to 14 C atoms or aliphatic dicarboxylic acids with 4 to 12 C atoms, for example Residues of phthalic acid, isophthalic acids, naphthalene-2,6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, succinic, adipic, sebacic acid, azelaic acid, cyclohexanediacetic acid.

0054In addition to ethylene glycol or 1,4-butanediol residues, they can contain up to 20 mol% of other aliphatic diols with 3 to 12 carbon atoms or cycloaliphatic diols with 6 to 21 carbon atoms, for example Residues of 1,3-propanediol, 2-1,3-propanediol, neopentylglycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexane-dimethanol, 2,4-3, methylpentanediol, 2- Methyl-pentanediol-2,4, 2,2,4-trimethylpentanediol-1,3 and -1,6, 2-ethylhexanediol-1,3, 2,2-diethyl-propanediol-1,3, hexanediol-2,5, 1,4 -Di- (ß-hydroxy-oxyethoxy) benzene, 2,2-bis (4-hydroxycyclohexyl) propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis - (3-B-hydroxyethoxyphenyl) propane and 2,2-bis (4-hydroxypropoxyphenyl) propane (DE-OS 24 07 674, 24th 07 776, 27 15 932).

0055The polyalkylene terephthalates can be branched by incorporating relatively small amounts of trihydric or tetravalent alcohols or trihydric or tetra-basic carboxylic acids, as are described, for example, in DE-OS 19 00 270 and US Pat. No. 3,692,744. Examples of preferred branching agents are trimesic acid, trimellitic acid, trimethylolethane and propane and pentaerythritol.

0056It is advisable not to use more than 1 mol% of the branching agent, based on the acid component.

0057Particularly preferred are polyalkylene terephthalates that consist solely of terephthalic acid and / or its reactive derivatives (e.g. whose dialkyl esters) and ethylene glycol or 1,4-butanediol have been prepared, mixtures of these polyalkylene terephthalates and copolyesters which are prepared from at least two of the abovementioned acid components and / or from at least two of the abovementioned alcohol components; particularly preferred copolyesters are poly-ethylene glycol / butanediol-1,4-terephthalate.

0058Very particularly suitable polyalkylene terephthalates have one _I.intrinsic viscosity of 0.4 to 1.5 dl / g, preferably 0.5 to 1.4 dl / g, in particular 0.6 to 1.3 dl / g, each measured in phenol / o-dichlorobenzene (1: 1 part by weight) at 25 ° C in an Ubbelohde viscometer. Thermoplastic polyesters A are also those which contain long-chain diols as the diol component. Preferred long-chain diols are dihydroxypolyethylene oxides of the gross formula HO (CH₂CH₂0)_nH and dihydroxytetrahydrofurans of the formula HO (CH2CH2CH2CH20) mH.

0059The average molecular weight (number average) of the long-chain diols is generally between 500 and 5,000, preferably between 1,000 and 3,000 (and n is thus approximately 10-100, preferably approximately 25-60; m approximately 7-70, preferably 14- 40).

0060Preferred polyesters with long-chain diols contain terephthalic acid and / or isophthalic acid as the acid component and dihydroxytetrahydrofuran and butanediol as the diol component, the content of condensed long-chain diol units generally being below 60% by weight, based on the total content of condensed diol units.

0061Depending on the desired properties, the thermoplastic polyesters can be used individually or in mixtures with one another.

0062Preferred mixtures contain polyethylene terephthalate and polybutylene terephthalate with 1-99, preferably 10-60, in particular 20-50,% by weight of polyethylene terephthalate, and 99-1, preferably 90-40, in particular 80-50,% by weight of polybutylene terephthalate.

0063For certain properties, up to 80% by weight, preferably up to 60% by weight, particularly preferably up to 40% by weight, based on A, of the thermoplastic polyester can be aromatic polycarbonates.

0064Aromatic polycarbonates for the purposes of this invention are understood to mean homopolycarbonates, copolycarbonates and mixtures of these polycarbonates which are based, for example, on at least one of the following diphenols:<ul id="ul0005" list-style="none"><li>Hydroquinone,</li><li>Resorcinol,</li><li>Dihydroxydiphenyls,</li><li>Bis (hydroxyphenyl) alkanes,</li><li>Bis (hydroxyphenyl) cycloalkanes,</li><li>Bis (hydroxyphenyl) sulfides,</li><li>Bis (hydroxyphenyl) ether,</li><li>Bis (hydroxyphenyl) ketones,</li><li>Bis (hydroxyphenyl) sulfoxides,</li><li>Bis (hydroxyphenyl) sulfones,</li><li>α, α'-bis (hydroxyphenyl) -diisopropylbenzenes and their nuclear alkylated and nuclear halogenated derivatives. These and other suitable diphenols are described, for example, in US Pat. Nos. 3,028,365, 3,275,601, 3,148,172, 3,062,781, 2,991,273, 3,271,367, 2,999,835, 2,970,131 and 2,999,846 DE-OS 1 570 703, 2 063 050, 2 063 052, 2 211 956, 2 211 957, FR-PS 1 561 518 and in the monograph by H. Schnell "Chemistry and Physics of Polycarbonates", Interscience Publishers, New York, 1964.</li></ul>

Preferred diphenols are, for example

00654,4'-dihydroxydiphenyl, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis (3-methyl -4-hydroxyphenyl) propane and 2,2-bis (3-chloro-4-hydroxyphenyl) propane.

Particularly preferred diphenols are, for example

00662,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) ) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane and 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane.

0067The aromatic polycarbonates can be branched by the incorporation of small amounts, preferably from 0.05 to 2.0 mol% (based on diphenols), of three or more than three-functional compounds, for example those with three or more than three phenolic hydroxyl groups .

0068The aromatic polycarbonates should generally have average molecular weights w of 10,000 to more than 200,000, preferably 20,000 to 80,000, determined by measuring the relative viscosity in dichloromethane at 25 ° C. and a concentration of 0.5% by weight.

0069Small proportions of low molecular weight polycarbonates, for example with an average degree of polycondensation of 2 to 20, can also be mixed into the high molecular weight polycarbonates with M of 10,000 to 200,000.

0070For adjusting the molecular weight <o>M</o>_w of the polycarbonates, chain terminators, such as, for example, phenol, halophenols or alkylphenols, are used in the calculated amounts in a known manner.

0071The molding compositions according to the invention can contain conventional additives, such as lubricants and mold release agents, nucleating agents, stabilizers, fillers and reinforcing materials, flame retardants, and also color pigments and / or dyes.

0072The filled or reinforced molding compositions can contain up to 60% by weight, based on the reinforced molding composition, of fillers and / or reinforcing materials. Preferred reinforcing materials are glass fibers. Preferred fillers, which can also have a reinforcing effect, are glass balls, mica, silicates, feldspar, quartz, talc, titanium dioxide, wollastonite.

0073The molding compositions finished with flame retardants contain flame retardants in a concentration of generally less than 30% by weight, based on the flame retardant molding compositions.

0074All known flame retardants are possible, such as, for example, polyhalodiphenyl, polyhalodiphenyl ether, polyhalophthalic acid and its derivatives and polyhalogenated oligo- and polycarbonates, the corresponding bromine compounds being particularly effective. They also usually contain a synergist, such as antimony trioxide.

0075The molding compositions can be produced in the usual mixing units, such as rollers, kneaders, single and multi-screw extruders.

0076Even though in most cases all the resin components are expediently mixed in one step, it can sometimes be advisable to omit one or even two components first and to mix them in at a later point in time.

0077Thus, the molding compositions according to the invention can be produced on the aforementioned mixing units by melting the two components A and B together and homogenizing them or by incorporating the graft product B into the melt of the thermoplastic polyester A.

0078The temperature in the preparation of the mixtures should be at least 10 ° C. and expediently at most 90 ° C. above the melting point of the polyester.

0079The molding compositions according to the invention are notable for improved toughness. An outstanding feature is the improvement in toughness at low temperatures.

0080According to the property profile, the molding compositions according to the invention are suitable everywhere in the injection molding and extrusion sector where molded parts are exposed to high shock loads, for example in the automotive sector for bumpers, spoilers, ramming strips, body parts, steering wheels, steering wheel columns.

0081The following examples illustrate the invention.

Examples

A) Components used

0082<ul id="ul0006" list-style="none"><li>I polybutylene terephthalate with an intrinsic viscosity of 1.18 dl / g, measured in phenol / o-dichlorobenzene (weight ratio 1: 1) at 25 ° C. in an Ubbelohde viscometer.</li><li>II polyethylene terephthalate with an intrinsic viscosity of 0.82 dl / g, measured as I.</li><li>III Polycarbonate from bisphenol A, phenol and phosgene, relative viscosity 1,285, measured in dichloromethane at 25 ° C in 0.5% by weight solution in an Ubbelohde viscometer.</li><li>IV Grafted polybutane diene rubber</li><li>IV.1 Production of polydiene latices</li><li>IV 1.1 In a reactor, the following emulsion is polymerized at 65 ° C. until the monomer conversion is virtually complete within about 22 hours:<img file="EP0131202A1_D0005.tif" /><img file="EP0131202A1_D0006.tif" />A latex is obtained which contains butadiene polymer particles of medium diameter (i.e.₅₀) of 0.1 µm in a concentration of approx. 35 - 36% by weight. The polybutadiene particles have gel contents of 90-95% by weight (measured in toluene at 23 ° C).</li><li>IV 1.2 According to regulation IV 1.1 the following emulsion is polymerized at 60 - 68 ° C within approx. 110 hours:<img file="EP0131202A1_D0007.tif" />A latex is obtained which contains medium diameter polybutadiene particles (i.e.₅₀) of 0.4 µm in a concentration of approx. 58% by weight. The polybutadiene particles have gel contents of 90-91% by weight (measured in toluene at 23 ° C).</li><li>_I.V 1.3 Polybutadiene latex, produced by emulsion polymerization using Na salt of disproportionated abietic acid as an emulsifier and potassium persulfate as an initiator, the polymerization being carried out in accordance with known measures in such a way that a finely divided latex with a broad particle distribution results. d₅₀-Value of the latex particles = 0.11 µm. The polybutadiene particles have a gel content of 93% by weight (measured analogously to IV 1.1).</li><li>IV 1.4 polybutadiene latex, produced with the addition of the auxiliaries described in IV 1.3. A coarse latex with a broad particle distribution is formed: d₅₀-Value of the latex particles = 0.39 µm. The polybutadiene particles have a gel content of 90% by weight (measured analogously to IV 1.1).</li><li>IV 1.5 Distribution characteristics of the rubber latices IV 1.1 to IV 1.4:<img file="EP0131202A1_D0008.tif" />d values: given in µm</li></ul>

IV

.2 Manufacture of graft products

0083A part by weight of polydiene latex and b parts by weight of water are placed in a reactor with stirring at 65 ° C. After initiation with c parts by weight of potassium persulfate, 100 parts by weight of styrene / acrylonitrile mixture (in a mixing ratio of 72:28) and separately a mixture of d parts by weight of water and e parts by weight of Na salt of the disproportionated abietic acid and f parts by weight of 1N sodium hydroxide solution were metered in over a period of several hours. The mixture is then left to polymerize to a final conversion of> 98% by weight at temperatures of 65 to 75 ° C. The amounts of these graft polymerizations are shown in the following table:<tables id="tabl0001" num="0001"><img file="EP0131202A1_D0009.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP0131202A1_D0010.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0131202A1_D0011.tif" /></tables><tables id="tabl0004" num="0004"><img file="EP0131202A1_D0012.tif" /></tables>

0084The comparative graft products V1, V2, V3 have a composition like type J (see Table 2).

V Grafted polyacrylate rubber

V1 Fine-particle acrylic rubber

0085The following are placed in a reactor:<ul id="ul0007" list-style="none"><li>1,030 parts by weight of water and 5 parts by weight of sodium salt of C₁₄-C₁₆-Alkylsulfonic acids.</li></ul>

008680 parts by weight of solution 1 (see below) are fed in at 70.degree. Then initiation is carried out by adding 5 parts by weight of potassium peroxydisulfate in 100 parts by weight of water. The following solutions are then dosed:

Solution 1: 995 parts by weight of n-butyl acrylate and 5 parts by weight of triallyl cyanurate (80 parts by weight of this solution have already been added to the initial charge, the rest of the solution is metered in after initiation!)

Solution 2: 20 parts by weight of sodium salt of C14-C18 alkyl sulfonic acids and 700 parts by weight of water.

0087After solutions 1) and 2) have been metered in in 5 hours at 70 ° C., polymerization is continued for 4 hours at 70 ° C. A latex with a solids content of 35% by weight is formed. The latex particle size is 0.09 µm (latex V1).

V2 Coarse-particle acrylic rubber

0088The following solutions are used:<ul id="ul0008" list-style="none"><li>Template 1: 12.4 parts by weight of latex IV 1.1 and 313 parts by weight of water,</li><li>Template 2: 0.82 parts by weight of potassium peroxydisulfate and 20 parts by weight of water,</li><li>Feed 1: 629 parts by weight, n-butyl acrylate and 1 part by weight of triallyl cyanurate,</li><li>Feed 2: 700 parts by weight of water and ₅,9 _Gparts by weight sodium salt of C14-C16-alkylsulfonic acids.</li></ul>

0089Template 1 is heated at 65-68 ° C., then 24 parts by weight of feed 1 are fed in. After initiation with template 2, the rest of feed 1 and feed 2 is metered in over 5 hours. Then stir for 4 hours.

0090The latex has a solids content of 37% by weight. The latex particle size is 0.5 µm (latex V2). The polymer has a gel content of 93% by weight and a swelling index¹⁾of 8, measured in DMF at 23 ° C.

0091¹⁾Definition of the source index: s. M. Hoffmann, H. Krömer, R. Kuhn, Polymeranalytik I and II, Georg Thieme Verlag Stuttgart 1977

0092V3 Production of the graft products from acrylate rubber and styrene / acrylonitrile mixture

0093General rule:<ul id="ul0009" list-style="none"><li>The following solutions or latices are used for polymerization in a reactor.<img file="EP0131202A1_D0013.tif" /></li></ul>

0094At 65 ° C, template 2 is fed into template 1, then feed 1 and feed 2 are metered in within 4 hours at 65 ° C. Then allowed to polymerize for 4 hours at 65 ° C (latex V.3).

0095The graft polymer latices are processed as follows:<tables id="tabl0005" num="0005"><img file="EP0131202A1_D0014.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP0131202A1_D0015.tif" /></tables>

0096Template 3 is heated to 70-73 ° C. with good stirring. Feed 3 is metered in within 1 hour. Then feed 4 is added within 30 minutes and then activated using the activator solution. The mixture is heated to 80 ° C., stirred for 2 hours, heated to 90 ° C. and stirred again for 2 hours. After subsequent stabilization with 2 parts by weight of phenolic antioxidants, the mixture is worked up to a powder by filtration, washing and drying.<tables id="tabl0007" num="0007"><img file="EP0131202A1_D0016.tif" /></tables><tables id="tabl0008" num="0008"><img file="EP0131202A1_D0017.tif" /></tables>

VI Vinyl monomer gop polymer is known

0097Copolymer of 72% by weight styrene and 28% by weight acrylonitrile with an intrinsic viscosity [η -] = 0.2 dl / g (measured in DMF in an Ubbelohde viscometer at 25 ° C).

B) Production and testing of the molding compounds

Examples 1-26

0098The components were melted and homogenized on a continuously operating twin-screw extruder. The cylinder temperatures were chosen so that the melt temperatures given in Tables 5-7 were observed. The melt strand was degassed before it emerged from the nozzle, cooled in water, granulated and dried.

0099Standard small bars were produced from the molding compositions on a conventional injection molding machine. The notched impact strength (according to DIN 53 453) was tested at the specified temperatures.

Examples 27-29

0100Analogously to experiments 1-26, the graft was mixed with molten polybutylene terephthalate in an extruder. Then cut glass fibers of 6 mm in length were metered into the mixed melt and distributed homogeneously. After degassing the melt in front of the nozzle, discharging the melt strand in water, granulating and drying, standard small bars were produced as previously described. The impact strength and impact strength at various temperatures were tested (in accordance with DIN 53 453). See Table 8 for results.<tables id="tabl0009" num="0009"><img file="EP0131202A1_D0018.tif" /></tables><tables id="tabl0010" num="0010"><img file="EP0131202A1_D0019.tif" /></tables><tables id="tabl0011" num="0011"><img file="EP0131202A1_D0020.tif" /></tables>The melt temperature in the extruder was 260 ° C, in the injection molding machine 250 ° C, the mold temperature was 80 ° C. The weights given relate to the molding compositions.<ul id="ul0010" list-style="none"><li>1) Comparative tests</li><li>2) not used = not broken<img file="EP0131202A1_D0021.tif" /><img file="EP0131202A1_D0022.tif" /><img file="EP0131202A1_D0023.tif" /></li></ul>