Thermoplastic moulding compounds.

0001Polyphenylene ethers are synthetic resins with excellent thermal, mechanical and electrical properties. Technically, a mixture of a polyphenylene ether and a styrene polymer is also produced. However, polyphenylene ether and the modified product mentioned have the disadvantage that they have only a low resistance to solvents. Their range of use is therefore limited. From US-PS 3379792 it is known that the melt flow property of polyphenylene ether is improved by the addition of a small amount of polyamide. However, it is also found in this document that when polyamide is added in an amount of more than 20%, other properties of the polyphenylene ether deteriorate to a considerable extent. From GB patent application 2054623 molding compounds made of polyphenylene ether and larger proportions of polyamides are also known. However, it is necessary to carry out a longer mixing process at the melting temperature. When mixing at melting temperature for a long time, however, signs of degradation easily occur.

0002The technical task was therefore to provide thermoplastic molding compositions which, in addition to being easy to process, have good thermal, mechanical and electrical properties and are particularly notable for high impact strength and good solvent resistance.

0003This object is achieved by containing thermoplastic molding compositions

0004A. 94.9 to 5 parts by weight of at least one polyphenylene ether which can be replaced up to half by styrene polymers

0005B. 5 to 94.9 parts by weight of at least one thermoplastic polyamide

0006C. 0,₁ up to 30 parts by weight of at least one copolymer composed of vinylaromatic monomers which are derived from benzene, which may be replaced up to a twelfth by acrylonitrile or methacrylonitrile and (meth) acrylic acid or its C 1 -C 4₁₂-Alkyl ester. With the proviso that the parts by weight of components A, B and C add up to 100 parts by weight and

0007D. optional additives in effective amounts.

0008The new thermoplastic molding compositions have the advantage that they are easy to process, have a high mechanical level and are also characterized by good impact resistance and solvent resistance.

0009The new thermoplastic molding compositions are noteworthy in that, according to the widespread opinion, mixtures of polyphenylene ether and a polyamide have no compatibility between the two plastics, since a phase separation usually occurs when such mixtures are molded, as can be seen from DE-OS 3027104.

0010The thermoplastic molding compositions according to the invention contain, as component A, 94.9 to 5 parts by weight of at least one polyphenylene ether. The polyphenylene ethers are compounds based on polyphenylene oxides which are substituted in the 2- and / or 6-position relative to the oxygen atom, in particular disubstituted, the ether oxygen of one unit being bound to the benzene nucleus of the adjacent unit. At least 50 units are advantageously linked to one another. Suitable polyphenylene ethers have, as substituents in the 2,6-position to the oxygen atom, halogen atoms, such as chlorine or bromine, alkyl radicals having 1 to 4 carbon atoms which have no tertiary hydrogen atom in the alpha position, for example methyl, ethyl, propyl or butyl radicals. The alkyl radicals can also be substituted by halogen atoms, such as chlorine or bromine, or by a hydroxyl group. Suitable polyphenylene ethers can furthermore contain alkoxy radicals having up to 4 carbon atoms or phenyl radicals which are optionally substituted by halogen atoms or alkyl groups. Examples are mentioned<ul id="ul0001" list-style="none"><li>Poly (2,5-dilauryl-1,4-phenylene) oxide,</li><li>Poly (diphenyl-1,4-phenylene) oxide,</li><li>Poly (2,6-dimethoxy-1,4-phenylene) oxide,</li><li>Poly (2,6-diethoxy-1,4-polyphenylene) oxide,</li><li>P_Oly (2-methoxy-6-ethoxy-1,4-phenylene) oxide,</li><li>Poly (2-ethyl-6-stearyloxy-1,4-phenylene) oxide,</li><li>Poly (2,6-dichloro-1,4-phenylene) oxide,</li><li>Poly (2-methyl-6-phenyl-1,4-phenylene) oxide,</li><li>Poly (2,6-dibenzyl-1,4-phenylene) oxide,</li><li>Poly (2-ethoxy-1,4-phenylene) oxide,</li><li>Poly (2-chloro-1,4-phenylene) oxide,</li><li>Poly (2,5-dibromo-1,4-phenylene) oxide. Copolymers of various phenols, such as 2,6-dimethylphenol and 2,3,6-trimethylphenol, are also suitable.</li></ul>

0011Particularly preferred for the mixtures according to the invention are those in which the substituents are alkyls with 1 to 4 carbon atoms, such as<ul id="ul0002" list-style="none"><li>Poly (2,6-dimethyl-1,4-phenylene) oxide,</li><li>Poly (2,6-diethyl-1,4-phenylene) oxide,</li><li>Poly (2-methyl-6-ethyl-1,4-polyphenylene) oxide,</li><li>Poly (2-methyl-6-propyl-1,4-phenylene) oxide,</li><li>Poly (2,6-dipropyl-1,4-phenylene) oxide and poly (2-etnyl-6-propyl-1,4-phenylene) oxide. The polyphenylene ethers used preferably have an intrinsic viscosity of 0.4 to 0.7 dl / g (measured in chloroform at 30 ° C.). Preferred molding compositions contain 20 to 70 parts by weight, in particular 3₅ up to 60 parts by weight of potyphenylene ether.</li></ul>

0012Up to half of the polyphenylene ethers used as component A can be replaced by styrene polymers. A tenth to half of the amount of polyphenylene ether is advantageously replaced by styrene polymers. Suitable styrene polymers are, for example, polystyrene, poly-a-methylstyrene or poly-p-methylstyrene, in particular polystyrene. Styrene polymers which are 2 to 20% by weight of a rubber-elastic polymer, in particular based on butadiene, for example, are particularly preferred Styrene-butadiene polymers or polybutadiene, furthermore containing butadiene-styrene block polymers. If styrene-diene block copolymers are used, it has proven useful to replace up to one fifth of the polyphenylene oxide content with butadiene or isoprene-styrene block copolymers or their hydrogenated products.

0013The molding compositions according to the invention contain, as component B, 5 to 94.9 parts by weight of at least one thermoplastic polyamide. Linear polyamides are suitable, for example, with a relative viscosity of 2.2 to 4.5, measured as 1 wt.^%solution in 96% by weight sulfuric acid at 23 ° C. Polyamides derived from lactams with 7 to 13 ring members, such as polycaprolactam, polycaprylactam or polylaurine lactam, and polyamides obtained by reacting dicarboxylic acids with diamines are preferred. Suitable dicarboxylic acids, which can also be used in any combination, are, for example, alkanedicarboxylic acids having 6 to 12, in particular 6 to 10, carbon atoms, terephthalic acid and isophthalic acid. Suitable diamines, which can also be used in any combination, are, for example, alkanediamines having 6 to 12, in particular 6 to 8, carbon atoms, also m-xylylenediamine, bis (4-aminophenyl) methane, bis (4-aminocyclohexyl) methane or bis (4- aminophenyl) propane-2,2. It is also possible to use mixtures of the polyamides mentioned. Polyamide-6, polyamide-66 and polyamides which are composed of hexamethylenediamine and isophthalic acid and terephthalic acid have acquired particular technical importance. Preferred molding compositions contain 5 to 70 parts by weight, in particular 25 to 60 parts by weight, of a thermoplastic polyamide.

0014As component C, the thermoplastic molding composition according to the invention contains 0.1 to 30 parts by weight of at least one copolymer which is composed of a vinylaromatic monomer which is derived from benzene and which can be replaced by acrylonitrile or methacrylonitrile up to a twelfth, and ( Meth) acrylic acid or its C, - to C₁₂-Alkyl ester. Suitable vinyl aromatic monomers are, for example, styrene, a-methylstyrene or p-methylstyrene, in particular styrene. In addition to methacrylic acid or acrylic acid, their C 1 -C 4 -alkyl esters, in particular the tert-butyl esters, are preferred.

0015Preferred copolymers are composed of 70 to 99.5% by weight of styrene, α-methylstyrene, p-methylstyrene or mixtures thereof, in particular styrene, and 0.5 to 30% by weight of (meth) acrylic acid or its tert-butyl ester. The polymers advantageously have a molecular weight of 5,000 to 200,000. Advantageous thermoplastic molding compositions according to the invention contain 0.5 to 30, in particular 5 to 20 parts by weight of component C.

0016Particularly preferred copolymers of styrene and acrylic acid are obtained by polymerizing the monomers in a suitable solvent, for example alkylbenzenes such as ethylbenzene. In a preferred embodiment, styrene and acrylic acid are polymerized at 140 ° C. with free radical initiator or preferably thermally (without starter) continuously at 9 bar and 4 h residence time. According to another procedure, polymers of styrene and acrylic acid are obtained by grafting acrylic acid onto polystyrene in the melt, for example at a temperature of 150 to 250 ° C., preferably using a radical initiator.

0017It is understood that the parts by weight of components A, B and C on ₁00 Add parts by weight.

0018In addition, the thermoplastic molding compositions according to the invention can optionally contain additives in effective amounts as component D. Heat and light stabilizers, lubricants and mold release agents, colorants such as dyes and pigments in customary amounts may be mentioned as additives. Suitable additives are also reinforcing agents, such as glass fibers, wollastonite, talc. Chalk, zinc sulfide, gypsum fibers, synthetic calcium silicates, kaolin, caicinated kaolin, in amounts of up to 50% by weight, preferably up to 30% by weight, based on the thermoplastic molding composition, furthermore phosphorus compounds, such as phosphates, phosphoric acid esters, phosphoric acid esters, phosphinic acid esters, phosphonous acid esters or organic phosphine oxides.

0019The thermoplastic molding compositions according to the invention are expediently obtained by mixing the individual components at temperatures from 230 to 320 ° C. in conventional mixing devices, such as extruders or kneaders. Components B and C are advantageously first mixed and then this mixture is mixed with component A. If part of component A is replaced by styrene polymers. it is advantageous to premix the polyphenylene ethers with styrene polymers and then to mix this mixture with a mixture of components B and C in the melt.

0020The thermoplastic molding compositions according to the invention are suitable for the production of moldings by injection molding or extrusion.

0021The object of the invention is illustrated by the following examples. The parts mentioned in the following examples are parts by weight.

Comparative Example 1

002245 Parts by weight of polyamide-6 with a relative viscosity of 3.5 and 55 parts by weight of poly (2,6-dimethyl-1,4-phenylene) ether with a viscosity of η = 0.6 are mixed on a Twin-shaft extruders mixed at a temperature of 290 ° C in the molten state, then extruded and granulated. The molding compound thus obtained is injection molded into test specimens. The properties are shown in the table below.

example 1

002345 Parts by weight of polyamide-6 with a relative viscosity of 3.5 are at a temperature of 290 ° C. with 10 parts by weight of a copolymer of 93% by weight of styrene and 7% by weight of acrylic acid, prepared by continuous solution polymerization, in mixed in an extruder and then mixed at this temperature with 45 parts by weight of poly (2,6-dimethylphenylene) ether, extruded, cooled and granulated. The properties of the molding composition thus obtained can be seen from the table below.

Example 2

0024The procedure is as described in Example 1, but using 40 parts by weight of polyamide-6, 5 parts by weight of the styrene-acrylic acid copolymer and 55 parts by weight of poly (2,6-dimethylphenylene) ether.

Example 3

002535 Parts by weight of polyamide-6 and 5 parts by weight of a copolymer of 95.5% by weight of styrene and 4.5% by weight of acrylic acid, produced by free-radical grafting of acrylic acid onto polystyrene in the melt, are in a twin-screw extruder mixed at a temperature of 290 ° C and then the melt mixed with 60 parts by weight of poly (2,6-dimethylphenylene) ether, the melt strained, cooled and granulated. The properties of the molding composition thus obtained can be seen from the table below.

Example 4

0026The procedure is as described in Example 3, but using 40 parts by weight of polyamide-6,6, 10 parts by weight of the styrene-acrylic acid copolymer and 50 parts by weight of poly (2,6-dimethylphenylene) ether.

Example 5

002725th Parts by weight of polyamide-6 with a relative viscosity of 3.5 and 10 parts by weight of a styrene-acrylic acid copolymer made from 95.5% by weight of styrene and 4.5% by weight of acrylic acid, prepared by radical grafting of acrylic acid on polystyrene in the melt, are mixed in an extruder at a temperature of 290 ° C, stranded and granulated (mixture A). Furthermore, 35 parts by weight of poly (2,6-dimethylphenylene) ether and 30 parts by weight of polystyrene with a content of 8% by weight, based on polystyrene, of a styrene-butadiene rubber at a temperature of 290 ° C. in mixed, extruded and granulated in an extruder (mixture B). 35 parts by weight of granulate A and 65 parts by weight of granulate B are mixed and plasticized in an extruder and mixed in the melt, then extruded, cooled and granulated. The properties of the molding composition thus obtained can be seen from the table below.

Example 6

002820 Parts of polycaprolactam, 5 parts of styrene-acrylic acid copolymer from 93% by weight of styrene and 7% by weight of acrylic acid, prepared by continuous solution polymerization, and 5 parts by weight of styrene-acrylic acid copolymer from 95.5% by weight of styrene and 4, 5% by weight of acrylic acid, prepared by free-radical grafting of acrylic acid onto molten polystyrene, are mixed, extruded and granulated in an extruder at a temperature of 290 ° C. (granules A). Furthermore, 40 parts by weight of poly (2,6-dimethylphenylene) ether and 30 parts by weight of polystyrene, which contains 8 parts by weight, based on polystyrene, of a styrene-butadiene rubber, are in an extruder at a temperature of 290 ° C mixed, stranded and granulated (granulate B). 30 parts by weight of granules A and 70 parts by weight of granules B are mixed and then plasticized in an extruder at 290 ° C. and mixed in the melt, extruded, cooled and granulated. The properties of the molding composition thus obtained can be seen from the table below.

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