Reinforced flame-resistant moulding compounds on the basis of thermoplastic polyester, and their use.

The present invention relates to reinforced flame-retardant thermoplastic polyester molding compositions and their use for the production of molded articles.

Flame retardant thermoplastic polyesters, which are additionally reinforced, are mainly used in the field of electrical engineering and electronics. Such polyester molds tend to form molten and possibly burning drops during the firing process, often fail to meet the safety requirements for such materials, and can therefore only be used to a limited extent.

It is known that, for suppressing the dripping of the melt formed under the action of an open flame from reinforced, flame-retardant molding compositions, for example certain gelling agents, such as finely divided silicates (DE-AS 24 08 531, FR-PS 2 322 900), silicic acid derivatives (DE- OS 22 26 931) or fillers with a length / diameter ratio of more than 50 (DE-AS 21 58 432) can be used. Examples of such additives are kaolin, talc, optionally organically modified bentonites and montmorillonites, glass spheres, surface-active silica, oligomeric sodium silicate, asbestos, graphite or glass fibers, silicon carbide, diatomaceous earth, etc. These anti-dripping agents are disadvantageous in that they cause a considerable reduction in the toughness properties of the resulting flame-retardant reinforced molding compositions, which impair their performance properties.

The invention relates to a flame-retardant reinforced polyester molding composition<ul id="ul0001" list-style="none"><li>a) a thermoplastic polyester,</li><li>b) 3 to 50% by weight of an amplifier filler,</li><li>c) 5 to 30% by weight of a flame retardant additive,</li><li>d) 0.2 to 4.0% by weight of an optionally organically modified layered silicate and which is characterized in that it additionally</li><li>e) contains 0.05 to 2.0% by weight of an alkali metal salt of an aliphatic monocarboxylic acid having 6-22 C atoms, the weight percentages based on the total weight of the molding composition.</li></ul>

The molding compositions according to the invention are notable for good toughness properties without the anti-drip and flame-retardant properties being impaired. In addition, components e) are effective even with small to very small additional amounts.

Components b) to e) which can be used are uniform compounds or substances or mixtures of different compounds or substances.

Linear thermoplastic polyesters suitable for the molding compositions according to the invention are preferably crystalline or partially crystalline and, in this case, in particular have melting points of at least 150 ° C. However, they can also be in amorphous form, in which case the polyester preferably has a glass transition temperature of at least 70 ° C., particularly at least 100 ° C. The viscosity number (according to DIN 53728/3) of the polyester is preferably at least 69 (cm³/ g), in particular at least 98 (cm³/G).

The polyesters can be homo- or mixed polyesters. Monomers that can be used for this purpose are, for example, straight-chain or branched saturated aliphatic, cycloaliphatic, aromatic or heterocyclic dicarboxylic acids or their esters, corresponding diols or corresponding hydroxycarboxylic acids. Mixtures of these polyesters are also suitable. Their composition depends essentially on the properties desired for a specific purpose.

The aliphatic dicarboxylic acids can have 2 to 40 C atoms, the cycloaliphatic dicarboxylic acids 6 to 10 C atoms, the aromatic dicarboxylic acids 8 to 14 C atoms, the heterocyclic dicarboxylic acids 5 to 12 C atoms, the aliphatic hydroxycarboxylic acids 2 to 12 C atoms and the aromatic and cycloaliphatic hydroxycarboxylic acids contain 7 to 13 carbon atoms and the heterocyclic hydroxycarboxylic acids contain 5 to 11 carbon atoms.

The aliphatic diols can contain 2 to 12 carbon atoms, the cycloaliphatic diols 5 to 8 carbon atoms, the aromatic diols 6 to 16 carbon atoms and the heterocyclic diols 3 to 16 carbon atoms.

Aromatic diols or dicarboxylic acids are those in which two hydroxyl or carboxyl groups are bonded to one or different aromatic hydrocarbon radicals.

It is also possible for the polyesters to be crosslinked with small amounts, for example 0.1 to 3 mol of Z, based on the dicarboxylic acids present, of a monomer having more than two carboxyl and / or hydroxyl groups (for example pentaerythritol or trimellitic acid). In the case of polyesters composed of at least 3 different monomers, these can be randomly distributed, or they can be block polymers.

Examples of aliphatic dicarboxylic acids having 2 to 40 carbon atoms are oxalic acid, malonic acid, dimethylmalonic acid, succinic acid, octadecylsuccinic acid, pimelic acid, adipic acid, trimethyladipic acid, sebacic acid, azelaic acid and dimer acid (dimerization products of unsaturated aliphatic carboxylic acids), such as Oels.

Possible cycloaliphatic dicarboxylic acids are: 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and 1,4-methylcyclohexanedicarboxylic acid, 4,4'-dicyclohexyldicarboxylic acid.

Suitable aromatic dicarboxylic acids are: terephthalic acid, isophthalic acid, phthalic acid, 1,3-, 1,4-, 2,6- or 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 1 , 1,3-trimethyl-5-carboxyl-3- (p-carboxyphenyl) indane, 4,4'-diphenylether dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid. Aromatic dicarboxylic acids are preferred, among them especially terephthalic acid, isophthalic acid and phthalic acid.

Further suitable dicarboxylic acids are those which contain -C0-NH groups, as described, for example, in DE-OS 2 414 349. Dicarboxylic acids containing N-heterocyclic rings are also suitable, for example those derived from carboxyalkylated, carboxyphenylated or carboxybenzylated monoamino-s-triazinedicarboxylic acids (cf. DE-OS 2 121 184 and 2 533 675), mono- or bishydantoins, optionally halogenated benzimidazolones or Derive parabanic acid. The carboxyalkyl group can contain 3 to 30 carbon atoms.

Suitable aliphatic diols can be linear or branched and preferably have 2 to 12, in particular 2 to 6, carbon atoms, such as, for example: ethylene glycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3-, 2, 3- or 1,4-butanediol, pentyl glycol, neopentyl glycol, 1,6-hexanediol, 1,12-dodecanediol. A suitable cycloaliphatic diol is, for example, 1,4-dihydroxycyclohexane. Other suitable diols are, for example 1,4-bis (hydroxymethyl) cyclohexane, aromatic aliphatic diols, such as p-dihydroxymethylbenzene or 2,5-dichloro-p-dihydroxymethylbenzene, and polyoxaalkylene glycols, such as diethylene glycol, triethylene glycol or polyethylene glycols. The alkylene diols are preferably linear and contain in particular 2 to 4 carbon atoms.

Preferred diols are the alkylene diols, 1,4-dihydroxycyclohexane and 1,4-bis (hydroxymethyl) cyclohexane. Ethylene glycol and 1,4-butanediol are particularly preferred.

Other suitable diols are the ß-hydroxyalkylated, especially ß-hydroxyethylated bisphenols, such as 2,2-bis [4 '- (ß-hydroxyethoxy) phenyl] propane. Other bisphenols are mentioned later.

Another group of suitable diols are the heterocyclic diols described in German Offenlegungsschriften 1,812,003, 2,342,432, 2,342,372 and 2,453,325. Examples are: N, N`-bis (β-hydroxyethyl) -5,5-dimethylhydantoin, N, N'-bis (β-hydroxypropyl) -5,5-dimethylhydantoin, methylene-bis [N- (β-hydroxyethyl) -5-methyl-5-ethylhydantoin], methylene-bis [N- (β-hydroxyethyl) -5,5-dimethylhydantoinj, N, N'-bis (ß-hydroxyethy1) benzimidazolone, - (tetrachlor) benzimidazolone or - (tetrabromo ) benzimidazolone.

Mononuclear diphenols and especially dinuclear ones which carry a hydroxyl group on each aromatic nucleus are suitable as aromatic diols. Aromatic is preferably understood to mean hydrocarbon-aromatic radicals, such as, for example, phenylene or naphthylene. In addition to, for example, hydroquinone and resorcinol, particular mention should be made of the bisphenols which can be represented by the following formula I.<chemistry id="chem0001" num="0001"><img file="EP0132228A2_D0001.tif" /></chemistry>

The hydroxyl groups can be in the m position, but especially in the p position, R 'and R "in this formula can denote alkyl having 1 to 6 carbon atoms, halogen, such as chlorine or bromine, and in particular hydrogen atoms. A can represent are a direct bond, or 0, S, S0₂, Unsubstituted or substituted by halogen, phenyl or alkylphenyl, preferably with 1 or 2 carbon atoms in alkyl, alkylidene, cycloalkylidene or alkylene.

Examples of optionally substituted alkylidene are: ethylidene, 1,1- or 2,2-propylidene, 2,2-butylidene, 1,1-isobutylidene, pentylidene, hexylidene, heptylidene, octylidene, dichloroethylidene, trichloroethylidene.

Examples of optionally substituted alkylene are methylene, ethylene, 1,2-propylene, phenylmethylene, diphenylmethylene, methylphenylmethylene. Examples of cycloalkylidene are cyclopentylidene, cyclohexylidene, cycloheptylidene and cyclooctylidene. The alkylidene, cycloalkylidene or alkylene groups A are preferably unsubstituted.

Examples of bisphenols are: Bis (p-hydroxyphenyl) ether or thioether, bis (p-hydroxyphenyl) sulfone, bis (p-hydroxyphenyl) methane, 1,2-bis (p-hydroxyphenyl) ethane, phenyl-bis (p-hydroxyphenyl) methane, diphenyl bis (p-hydroxyphenyl) methane, 2,2-bis (4'-hydroxy-3'-methylphenyl) propane, 1,1- or 2,2-bis (p-hydroxyphenyl) butane, 1,1-dichloro- or 1,1,1-trichloro-2,2-bis (p-hydroxyphenyl) ethane, 1,1-bis (p-hydroxyphenyl) cyclopentane and especially 2,2-bis (p-hydroxyphenyl) propane (bisphenol-A) and 1,1-bis (p-hydroxyphenyl) cyclohexane (bisphenol-C).

Suitable polyesters from hydroxycarboxylic acids are, for example, polycaprolactone, polypivalolactone or the polyesters from 4-hydroxycyclohexane carboxylic acid or 4-hydroxybenzoic acid.

Linear polyesters derived from aromatic dicarboxylic acids have gained the greatest importance, especially the polyalkylene terephthalates. Molding compositions according to the invention are therefore preferred in which the polyester is composed of at least 30 mol%, preferably at least 40 mol%, aromatic dicarboxylic acids and at least 30 mol%, preferably at least 40 mol%, of alkylene diols having preferably 2 to 12 carbon atoms, based on the polyester.

In this case, in particular, the alkylene diol is linear and contains 2 to 6 carbon atoms, such as, for example, ethylene, tri, tetra or hexamethylene glycol and the aromatic dicarboxylic acid terephthalic and / or isophthalic acid. Particularly preferred as polyesters are polyethylene and poly-1,4-butylene terephthalate and copolyesters based on polyethylene and poly-1,4-butylene terephthalate. Poly-1,4-butylene terephthalate (PBTP) is very particularly preferred.

The molding compound according to the definition preferably contains the reinforcing filler in the form of fibers, for example asbestos fibers, carbon fibers or in particular glass fibers. The fillers can be coated with an adhesion promoter in order to improve their binding to the polyester. The amount of the reinforcing filler is preferably 10 to 50% by weight, particularly preferably 10 to 40% by weight and very particularly preferably 25 to 35% by weight, based on the total mass.

The molding compound according to the definition contains in particular 10 to 20% by weight, based on the total mass, of a flame-retardant additive.

Suitable flame retardant additives are, for example, organic halogen compounds, especially chlorine or bromine compounds, which are used alone or together with synergistic compounds with elements of the fifth main group of the periodic table, especially phosphorus and antimony compounds, especially antimony trioxide.

Flame retardants based on organic chlorine and / or especially bromine-containing compounds are known. These can be those which are incorporated into the plastic as a mixing component, or those which are incorporated into the polymer molecules as reactive monomers. Examples of the latter are tetrachlorophthalic anhydride, dichloroterephthalic acid or their lower alkyl esters, tetrabromophthalic anhydride, tetrabromobisphenol-A, N, N'-bis (β-hydroxyethyl) tetrachloro- or tetrabromobenzimidazolone.

Further examples of chlorine and / or bromine-containing compounds are: Brominated polystyrenes, polytribromostyrene example, polypentabromostyrene, decabromobiphenyl, tetrabromobiphenyl, hexabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether, Tetrabromdiphenylsulfid, Hexabromdiphenylsulfon, 3- (2 ', 4', 6'-tribromophenoxy) -1 , 2-propanediol, di- or tetrabromophthalic acid or their anhydrides, dibromoterephthalic acid, hydroxyethylated di- or tetrabromobisphenol-A, tetrabromo-1,4-bis (hydroxymethyl) benzene, tetrabromobenzimidazolone, N, N'-ethylene-bis-tetrabromophthalimide and the chlorine-analogous compounds. Further organic halogen compounds are described, for example, in German Offenlegungsschrift No. 2,242,450.

The preferred flame retardant is a combination of antimony trioxide with brominated polystyrene or with N, N'-ethylene-bis-tetrabromophthalimide, and particularly preferably with decabromodiphenyl ether.

The layered silicate anti-drip agent used according to the invention can be a smectite, in particular a bentonite or montmorillonite. It is also possible to use organically modified snectites, in particular with organic ammonium salts, in which the organic radicals can be, for example, phenyl, benzyl or alkyl groups. Ammonium salts which have at least one long-chain alkyl group are preferred, especially tetraalkylammonium salts with one or two alkyl groups with, for example, 10 to 25 C atoms, in particular with 16 to 20 C atoms. Preferred products of this type are known under the trade names Claytone® (China-Clay Handelsgesellschaft, Düsseldorf, FRG), or Bentone® (NL Chemicals, Wilmslow, UK). Claytone® 34 or 40 (both dimethyl-dioctadecyl-ammonium-bentonite) or Bentone® 27, 34 (dimethyl-dioctadecyl ammonium montmorillonite), 38, 500 or SD-1 are used, with Bentone® 500 and Bentone® SD-1 being particularly preferred.

The phyllosilicates are preferably used in a total amount of 0.75 to 2.0 parts by weight based on the total mass.

As the alkali metal salts e), the molding compositions according to the invention contain, in particular, sodium or potassium salts of saturated or unsaturated aliphatic monocarboxylic acids with 10 to 20 C atoms, preferably with 14 to 18 C atoms. Preferred alkali metal salts are potassium and / or sodium stearate, potassium and / or sodium oleate, in particular potassium oleate. Component e) is preferably present in a total amount of 0.05 to 1% by weight, in particular 0.1 to 0.6% by weight, based on the total mass.

The thermoplastic polyesters are known and commercially available or they can be produced by known polycondensation processes in the art.

The molding compositions according to the invention are likewise produced by methods customary in industry by incorporating the additives into the thermoplastic polyester, for example by regranulation. The layered silicate and the alkali metal salt can also be drummed onto the polyester granulate.

Other customary additives can also be added, for example further fillers, such as talc, mica, metal powder, silicic acid aerosol, kaolin, calcium carbonate, dolomite, magnesium sulfate, silicates or glass spheres, inorganic or organic pigments, optical brighteners, matting agents, lubricants, mold release agents, crystallization-promoting agents Agents, antioxidants, light stabilizers and processing stabilizers.

In the case of the molding compositions according to the invention, the dripping of the melt during flame treatment is effectively prevented. Furthermore, due to the addition of the alkali metal salts, aliphatic C_6-22 Monocarboxylic acids largely maintain the good toughness properties of the molding compositions. The incorporation of the additives is easy and an even distribution in the molding compound is achieved.

The molding compounds can be processed into everyday articles of all kinds using customary shaping processes such as casting, pressing, injection molding and extrusion. Examples of such objects are technical apparatus parts, apparatus housings, household appliances, sports equipment, electrical insulation, automotive parts, circuits, plates, films and semi-finished products, which can be deformed by machining. A special area of ​​application is the production of molded articles or Enclosures for electrical engineering and electronics.

The following examples illustrate the invention. The percentages by weight of the individual components given in the examples are always based on the total mass.

Examples 1-9: The components listed in Table 1 are made using a laboratory co-kneader at 250 ° C in polybutylene terephthalate (viscosity number according to DIN 53728/3 102 cm³/ g) incorporated and the molding compound is granulated. After the granules have dried, they are processed into molded articles by injection molding (125 x 12.5 x 1.6 mm for the flammability test and 6 x 4 x 50 mm for the impact resistance test) according to the following conditions:<ul id="ul0002" list-style="none"><li>Cylinder temperature 250 ° C</li><li>Tool temperature 80 ° C</li><li>Cycle time 45 sec.</li></ul>

Examples 10-12: The four components listed first in Table 1 (PBTP, glass fibers, flame retardants and Sb₂0₃) are processed with the help of a laboratory co-kneader into the molding compound, and the molding compound is granulated. After the granules have dried, the last two components (layered silicate and alkali metal salt) are tumbled in a tumble mixer, and then, as described above, injection moldings are produced.

The flammability in accordance with UL 94 and the impact strength in accordance with DIN 53453 are determined on the shaped bodies. During the flammability test, the molded parts proved to be self-extinguishing V-0 and not dripping. In the impact test, the test pieces turned out to be impact-resistant, the impact strength varying depending on the type and amount of the layered silicate d) and the alkali metal salt e).<tables id="tabl0001" num="0001"><img file="EP0132228A2_D0002.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP0132228A2_D0003.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0132228A2_D0004.tif" /></tables><tables id="tabl0004" num="0004"><img file="EP0132228A2_D0005.tif" /></tables><tables id="tabl0005" num="0005"><img file="EP0132228A2_D0006.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP0132228A2_D0007.tif" /></tables>