WO2004056914A1

WO2004056914A1 - Electrically insulating and thermally conductive polyester molding materials

Info

Publication number: WO2004056914A1
Application number: PCT/EP2003/014281
Authority: WO
Inventors: Michael GEPRÄGS
Original assignee: Basf Aktiengesellschaft
Priority date: 2002-12-19
Filing date: 2003-12-16
Publication date: 2004-07-08
Also published as: AU2003293893A1; DE10260098A1

Abstract

The invention relates to thermoplastic molding materials containing A) 10 to 70 percent by weight of a thermoplastic polyester, B) 30 to 85 percent by weight of an aluminum oxide, C) 0 to 5 percent by weight of at least one ester or amide of saturated or unsaturated aliphatic carboxylic acids comprising 10 to 40 C atoms along with aliphatic saturated alcohols or amines comprising 2 to 40 C atoms, D) 0 to 60 percent by weight of other additives, the total percentage by weight of components A) to D) being 100 percent.

Description

Electrically insulating and thermally conductive polyester mold

description

The invention relates to thermoplastic molding compositions containing

A) 10 to 70 wt .-% of a thermoplastic polyester

B) 30 to 85% by weight of an aluminum oxide

C) 0 to 5% by weight of at least one ester or amide of saturated or unsaturated aliphatic carboxylic acids with 10 to 40 C atoms with aliphatic saturated alcohols or amines with 2 to 40 C atoms

D) 0 to 60% by weight of further additives,

the sum of the percentages by weight of components A) to D) being 100%.

Furthermore, the invention relates to the use of the molding compositions according to the invention for the production of fibers, films and moldings of any kind, and to the moldings obtainable here.

Conventional cooling elements show a general structure of heat sinks z. B. essentially made of AI Mg Si, which are connected via connection units with power chips for controlling the cooling. The connection units generally consist of heat-conducting pastes and an electrical insulator (mica flakes or aluminum oxide flakes). Heating elements have a similar structure. In general, a design consists of an electrical heating element and a heat-conducting substrate. As a rule, the heating element is a metallic resistance wire that has to be introduced into the heat-conducting substrate.

Problems with tightness often arise from the use of different materials, since the metals and chips as well as the connection units have different expansion coefficients. The production of such an element is correspondingly complex. Replacing the connection units and also the metal parts in these elements with plastics is problematic since, in addition to a high thermal conductivity, an electrically insulating property of the thermoplastic composition is also imperative.

At the same time, the surface should above all be smooth, printable, markable and have sufficient hardness and surface roughness, which can usually only be achieved on a limited scale with high filler contents (due to sufficient conductivity).

The present invention was therefore based on the object of providing thermoplastic polyester molding compositions which have good flowability / thermal conductivity and at the same time have an electrically insulating property. In particular, the surface of the molded parts should be smooth and versatile. Accordingly, the molding compositions defined at the outset were found. Preferred embodiments can be found in the subclaims.

The molding compositions according to the invention contain 10 to 70, preferably 15 to 95 and in particular 20 to 44.9% by weight of a thermoplastic polyester as component (A).

Polyesters A) based on aromatic dicarboxylic acids and an aliphatic or aromatic dihydroxy compound are generally used.

A first group of preferred polyesters are polyalkylene terephthalates, in particular with 2 to 10 carbon atoms in the alcohol part.

Such polyalkylene terephthalates are known per se and are described in the literature. They contain an aromatic ring in the main chain, which comes from the aromatic dicarboxylic acid. The aromatic ring can also be substituted, for example by halogen such as chlorine and bromine or by C 1 -C ₄ alkyl groups such as methyl, ethyl, i- or n-propyl and n-, i- or t-butyl groups.

These polyalkylene terephthalates can be prepared in a manner known per se by reacting aromatic dicarboxylic acids, their esters or other ester-forming derivatives with aliphatic dihydroxy compounds.

Preferred dicarboxylic acids are 2,6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid or mixtures thereof. Up to 30 mol%, preferably not more than 10 mol%, of the aromatic dicarboxylic acids can be replaced by aliphatic or cycloaliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acids and cyclohexanedicarboxylic acids.

Of the aliphatic dihydroxy compounds, diols having 2 to 6 carbon atoms, in particular 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1 , 4-Cyclohexanedimethanol and neopentyl glycol or mixtures thereof are preferred.

Particularly preferred polyesters (A) are polyalkylene terephthalates which are derived from alkanediols having 2 to 6 carbon atoms. Of these, particularly preferred are polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate or mixtures thereof. Also preferred are PET and / or PBT, which contain up to 1% by weight, preferably up to 0.75% by weight, of 1,6-hexanediol and / or 2-methyl-1,5-pentanediol as further monomer units.

The viscosity number of the polyesters (A) is generally in the range from 50 to 220, preferably from 80 to 160 (measured in a 0.5% strength by weight solution in a phenol / o-dichlorobenzene mixture (weight ratio 1: 1 at 25 ° C) according to ISO 1628. Particularly preferred are polyesters whose carboxyl end group content is up to 100 meq / kg, preferably up to 50 meq / kg and in particular up to 40 meq / kg polyester. Such polyesters can be produced, for example, by the process of DE-A 4401 055. The carboxyl end group content is usually determined by titration methods (eg potentiometry).

Particularly preferred molding compositions contain, as component A), a mixture of polyesters other than PBT, such as, for example, polyethylene terephthalate (PET). The proportion e.g. The polyethylene terephthalate in the mixture is preferably up to 50, in particular 10 to 35,% by weight, based on 100% by weight of A).

Furthermore, it is advantageous to use PET recyclates (also called scrap PET), optionally in a mixture with polyalkylene terephthalates such as PBT.

Recyclates are generally understood to mean:

1) So-called post industrial recyclate: this is production waste from polycondensation or processing e.g. Sprues in injection molding processing, approach goods in injection molding processing or extrusion or edge sections of extruded sheets or foils.

2) Post consumer recyclate: these are plastic items that are collected and processed by the end consumer after use. The most dominant item in terms of quantity are blow-molded PET bottles for mineral water, soft drinks and juices.

Both types of recyclate can either be in the form of regrind or in the form of granules. In the latter case, the pipe cyclates are melted and granulated in an extruder after separation and cleaning. This usually facilitates handling, flowability and meterability for further processing steps.

Recyclates, both granulated and in the form of regrind, can be used, the maximum edge length being 10 mm, preferably less than 8 mm.

Due to the hydrolytic cleavage of polyester during processing (due to traces of moisture), it is advisable to predry the recyclate. The residual moisture content after drying is preferably <0.2%, in particular <0.05%.

Fully aromatic polyesters derived from aromatic dicarboxylic acids and aromatic dihydroxy compounds should be mentioned as a further group.

Aromatic dicarboxylic acids are the compounds already described for the polyalkylene terephthalates. Mixtures of 5 to 100 mol% isophthalic acid and 0 to 95 mol% terephthalic acid are preferred, in particular mixtures of about 80% terephthalic acid. acid with 20% isophthalic acid to about equivalent mixtures of these two acids used.

The aromatic dihydroxy compounds preferably have the general formula

in which Z represents an alkylene or cycloalkylene group with up to 8 C atoms, an arylene group with up to 12 C atoms, a carbonyl group, a sulfonyl group, an oxygen or sulfur atom or a chemical bond and in which m is from 0 to 2 has. The compounds can also carry C ₁ -C ₆ -alkyl or alkoxy groups and fluorine, chlorine or bromine as substituents on the phenylene groups.

As the stem body of these compounds, for example

dihydroxydiphenyl,

Di (hydroxyphenyl) alkane, di (hydroxyphenyl) cycloalkane,

Di (hydroxyphenyl) sulfide,

Di (hydroxyphenyl) ether,

Di- (hydroxyphenyl) ketone, di- (hydroxyphenyl) sulfoxide, -r, σ'-di- (hydroxyphenyl) dialkylbenzene,

Di (hydroxyphenyl) sulfone, di (hydroxybenzoyl) benzene

Resorcinol and

Hydroquinone and their nuclear alkylated or nuclear halogenated derivatives called.

Of these will be

4,4'-dihydroxydiphenyl, 2,4-di- (4'-hydroxyphenyl) -2-methylbutane σ, σ'-di- (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-di- (3'- methyl-4'-hydroxyphenyl) propane and 2,2-di- (3'-chloro-4'-hydroxyphenyl) propane,

as well as in particular

2,2-di- (4'-hydroxyphenyl) propane

2,2-di- (3 ', 5-dichlordihydroxyphenyl) propane,

1,1-di- (4'-hydroxyphenyl) cyclohexane,

3,4'-dihydroxybenzophenone,

4,4'-dihydroxydiphenyl sulfone and 2,2-di (3 ', 5'-dimethyM'-hydroxyphenyl) propane or mixtures thereof are preferred.

Mixtures of polyalkylene terephthalates and fully aromatic polyesters can of course also be used. These generally contain 20 to 98% by weight of the polyalkylene terephthalate and 2 to 80% by weight of the fully aromatic polyester.

Of course, polyester block copolymers such as copolyether esters can also be used. Such products are known per se and are known in the literature, e.g. in US-A 3,651,014. Corresponding products are also available commercially, e.g. Hytrel® (DuPont).

According to the invention, polyester should also be understood to mean halogen-free polycarbonates. Suitable halogen-free polycarbonates are, for example, those based on diphenols of the general formula

wherein Q is a single bond, a C, - to C ₈ -alkylene, a C ₂ - to C ₃ -alkylidene, a Gabis C ₆ -cycloalkylidene group, a C ₆ - to C ₁₂ -arylene group and -O-, -S - or -SO ₂ - and m is an integer from 0 to 2.

The diphenols can also have substituents on the phenylene radicals, such as C 1 -C ₆ -alkyl or C 1 -C ₆ -alkoxy.

Preferred diphenols of the formula are, for example, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, 2,2-bis (4-hydroxyphenyl) propane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 1, 1 bis (4-hydroxyphenyl) -cyclohexane. 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5- are particularly preferred. trimethylcyclohexane.

Both homopolycarbonates and copolycarbonates are suitable as component A; in addition to the bisphenol A homopolymer, the copolycarbonates of bisphenol A are preferred.

The suitable polycarbonates can be branched in a known manner, preferably by incorporating 0.05 to 2.0 mol%, based on the sum of the diphenols used, of at least trifunctional compounds, for example those having three or more than three phenolic compounds OH groups.

Polycarbonates which have relative viscosities η _rei of 1.10 to 1.50, in particular of 1.25 to 1.40, have proven to be particularly suitable. This corresponds to average molecular weights M _w (weight average) of 10,000 to 200,000, preferably from 20,000 to 80,000 g / mol. The diphenols of the general formula are known per se or can be prepared by known processes.

The polycarbonates can be prepared, for example, by reacting the diphenols with phosgene by the interfacial process or with phosgene by the process in a homogeneous phase (the so-called pyridine process), the molecular weight to be set in each case being achieved in a known manner by a corresponding amount of known chain terminators. (Regarding polydiorganosiloxane-containing polycarbonates, see for example DE-OS 33 34 782).

Suitable chain terminators are, for example, phenol, pt-butylphenol but also long-chain alkylphenols such as 4- (1,3-tetramethylbutyl) phenol, according to DE-OS 2842 005 or monoalkylphenols or dialkylphenols with a total of 8 to 20 carbon atoms in the Alkyl substituents according to DE-A 35 06472, such as p-nonylphenyl, 3,5-di-t-butylphenol, pt-octylphenol, p-dodecylphenol, 2- (3,5-dimethy! -Heptyl) -phenol and 4- (3rd , 5-dimethylheptyl) -phenol.

Halogen-free polycarbonates in the sense of the present invention means that the polycarbonates are composed of halogen-free diphenols, halogen-free chain terminators and optionally halogen-free branching agents, the content of minor ppm amounts of saponifiable chlorine resulting, for example, from the production of the polycarbonates with phosgene by the phase interface process. is not to be regarded as containing halogen in the sense of the invention. Such polycarbonates with ppm contents of saponifiable chlorine are halogen-free polycarbonates in the sense of the present invention.

Amorphous polyester carbonates may be mentioned as further suitable components A), phosgene being replaced by aromatic dicarboxylic acid units such as isophthalic acid and / or terephthalic acid units during production. For further details, reference is made to EP-A 711 810.

Further suitable copolycarbonates with cycloalkyl radicals as monomer units are described in EP-A 365 916.

Bisphenol A can also be replaced by Bisphenol TMC. Such polycarbonates are available under the trademark APEC HT® from Bayer.

As component B), the molding compositions according to the invention contain 30 to 85, preferably 40 to 85 and in particular 55 to 80% by weight of an aluminum oxide. The component B) preferably has an average particle size (d ₅ o value) of less than 20 microns, preferably less than 10 microns.

A d ₅₀ value is generally understood by the person skilled in the art to mean the particle size value, in which 50% of the particles have a smaller particle size and 50% have a larger particle size. The d ₁₀ value is preferably less than 10 μm, in particular less than 5 μm and very particularly preferably less than 2.2 μm.

Preferred d _go values are less than 50 μm and in particular less than 30 μm and very particularly preferably less than 30 μm.

Aluminum oxides (alumina), Al ₂ 0 ₃ , MG. 101.96. The oxides occur in various modifications, of which the hexagonal α-oxide is the only thermodynamically stable modification. The face-centered cubic -AI ₂ 0 ₃ is also well characterized. It arises from the aluminum hydroxides by heating to 400-800 ° C and, like the other modifications, can be converted to -.- Al ₂ 0 ₃ by annealing to over 1100 °. Jff-AI ₂ 0 ₃ is a group of oxides that contain small amounts of foreign ions in the crystal lattice. Other modifications, like the numerous transitional forms between the aluminum hydroxides and the two, are of lesser importance. Preferred is σ-Al ₂ 0 ₃ , density 3.98, hardness 9, mp. 2053 °, which is insoluble in water, acids and. Bases is. Technically, the σ-AI ₂ 0 _{3 is obtained} from bauxite using the Bayer process. The main amount is used for the electrolytic production of aluminum. The oxides are a thin protective layer on aluminum; this oxide layer can be reinforced by chemical or anodic oxidation.

In nature, σ-AI ₂ 0 _{3 occurs} as corundum, mp 2050 °. Corundum is mostly clouded by impurities and often also colored. Today, corundum is technically extracted as electrical corundum; this melts Al ₂ 0 ₃ obtained from bauxite. in the electric arc furnace over 2000 °. This gives a very hard product with about 99% σ-AI 0 ₃ .

The so-called active oxides are obtained by precipitation processes from aluminum salt solution - e.g. B. over thermally post-treated aluminum hydroxide gels - or by calcination from a-aluminum hydroxide at low temperatures or by shock heating.

Component B) preferably has a specific surface area according to BET (according to DIN 60 132 or ASTM D 3037) of at least 0.1, preferably 0.3 m ² / g.

The preferred density is 2.5 to 4.5, in particular 3.9 to 4.0 g / an ³ .

The sodium oxide content is preferably less than 0.4, in particular from 0.10 to 0.35% by weight, based on 100% by weight of B).

The thermal conductivity according to DIN 52612 is preferably at least 20 W / mK and in particular at least 25 W / mK.

As component C) the molding compositions according to the invention can contain 0 to 5, preferably 0.05 to 3 and in particular 0.1 to 2% by weight of at least one ester or amide of saturated or unsaturated aliphatic carboxylic acids with 10 to 40, preferably 16 to 22, Contain atoms with aliphatic saturated alcohols or amines with 2 to 40, preferably 2 to 6, carbon atoms. The carboxylic acids can be 1- or 2-valent. Examples include pelargonic acid, palmitic acid, lauric acid, margaric acid, dodecanedioic acid, behenic acid and particularly preferably stearic acid, capric acid and montanic acid (mixture of fatty acids with 30 to 40 carbon atoms).

The aliphatic alcohols can be 1- to 4-valent. Examples of alcohols are n-butanol, n-octanol, stearyl alcohol, ethylene glycol, propylene glycol, neopentyl glycol, pentaerythritol, with glycerol and pentaerythritol being preferred.

The aliphatic amines can be 1- to 3-valent. Examples include stearylamine, ethylenediamine, propylenediamine, hexamethylenediamine, di (6-aminohexyl) amine, ethylenediamine and hexamethylenediamine being particularly preferred. Preferred esters or amides are correspondingly glycerol distearate, glycerol tristearate, ethylenediamine distearate, glycerol monopalmitate, glycerol trilaurate, glycerol monobehenate and pentaerythritol tetrastearate.

Mixtures of different esters or amides or esters with amides can also be used in combination, the mixing ratio being arbitrary.

As component D), the molding compositions according to the invention can contain 0 to 60, in particular up to 50% by weight of further additives and processing aids which are different from B) and / or C).

Customary additives D) are, for example, in amounts of up to 40, preferably up to 30% by weight of rubber-elastic polymers (often also referred to as impact modifiers, elastomers or rubbers).

In general, these are copolymers which are preferably composed of at least two of the following monomers: ethylene, propylene, butadiene, isobutene, isoprene, chloroprene, vinyl acetate, styrene, acrylonitrile and acrylic or methacrylic acid esters with 1 to 18 carbon atoms in the alcohol component.

Such polymers are e.g. in Houben-Weyl, Methods of Organic Chemistry, Vol. 14/1 (Georg-Thieme-Verlag, Stuttgart, 1961). Pages 392 to 406 and in the monograph by C.B. Bucknall, "Toughened Plastics" (Applied Science Publishers, London, 1977).

Some preferred types of such elastomers are presented below.

Preferred types of such elastomers are the so-called ethylene-propylene (EPM) or ethylene-propylene-diene (EPDM) rubbers.

EPM rubbers generally have practically no more double bonds, while EPDM rubbers can have 1 to 20 double bonds / 100 carbon atoms. Examples of diene monomers for EPDM rubbers are conjugated dienes such as isoprene and butadiene, non-conjugated dienes having 5 to 25 carbon atoms such as penta-1,4-diene, hexa-1,4-diene, hexa-1,5 -diene, 2,5-dimethylhexa-1,5-diene and octa-1, 4-diene, cyclic dienes such as cyclopentadiene, cyclohexadienes, cyclooctadienes and dicyclopentadiene, and alkenylnorbomenes such as 5-ethylidene-2-norbornene, 5-butylidene- 2-norbornene, 2-methallyl-5-norbornene, 2-isopropenyl-5-norbornene and tricyclodienes such as 3-methyl-tricyclo (5.2.1.0.2.6) -3,8-decadiene or mixtures thereof. Hexa-1,5-diene, 5-ethylidene norbornene and dicyclopentadiene are preferred. The diene content of the EPDM rubbers is preferably 0.5 to 50, in particular 1 to 8,% by weight, based on the total weight of the rubber.

EPM or EPDM rubbers can preferably also be grafted with reactive carboxylic acids or their derivatives. Here are e.g. Acrylic acid, methacrylic acid and their derivatives, e.g. Glycidyl (meth) acrylate, as well as maleic anhydride.

Another group of preferred rubbers are copolymers of ethylene with acrylic acid and / or methacrylic acid and / or the esters of these acids. In addition, the rubbers can also contain dicarboxylic acids such as maleic acid and fumaric acid or derivatives of these acids, e.g. Contain esters and anhydrides, and / or monomers containing epoxy groups. These dicarboxylic acid derivatives or monomers containing epoxy groups are preferably incorporated into the rubber by adding monomers of the general formulas I or II or III or IV containing dicarboxylic acid or epoxy groups to the monomer mixture

R ¹ C (COOR ² ) = C (COOR ³ ) R ⁴ (I)

R ⁴ ^R \ /

C C

I I

I I (li) CO. ^ CO O

HR "(III)

where R ¹ to R ^{9 represent} hydrogen or alkyl groups having 1 to 6 carbon atoms and m is an integer from 0 to 20, g is an integer from 0 to 10 and p is an integer from 0 to 5

The radicals R ¹ to R ^{9 are} preferably hydrogen, where m is 0 or 1 and g is 1. The corresponding compounds are maleic acid, fumaric acid, maleic anhydride, allyl glycidyl ether and vinyl glycidyl ether. Preferred compounds of the formulas I, II and IV are maleic acid, maleic anhydride and epoxy group-containing esters of acrylic acid and / or methacrylic acid, such as glycidyl acrylate, glycidyl methacrylate and the esters with tertiary alcohols, such as t-butyl acrylate. Although the latter have no free carboxyl groups, their behavior comes close to that of the free acids and is therefore referred to as monomers with latent carboxyl groups.

The copolymers advantageously consist of 50 to 98% by weight of ethylene, 0.1 to 20% by weight of monomers containing epoxy groups and / or monomers containing methacrylic acid and / or monomers containing acid anhydride groups and the remaining amount of (meth) acrylic acid esters.

Copolymers of are particularly preferred

50 to 98, in particular 55 to 95% by weight of ethylene,

0.1 to 40, in particular 0.3 to 20% by weight of glycidyl acrylate and / or glycidyl methacrylate, (meth) acrylic acid and / or maleic anhydride, and

1 to 45, in particular 10 to 40% by weight of n-butyl acrylate and / or 2-ethylhexyl acrylate.

Further preferred esters of acrylic and / or methacrylic acid are the methyl, ethyl, propyl and i- or t-butyl esters.

In addition, vinyl esters and vinyl ethers can also be used as comonomers.

The ethylene copolymers described above can be prepared by processes known per se, preferably by random copolymerization under high pressure and elevated temperature. Appropriate methods are generally known.

Preferred elastomers are also emulsion polymers, the production of which e.g. is described in Blackley in the monograph "Emulsion Polymerization". The emulsifiers and catalysts that can be used are known per se.

In principle, homogeneous elastomers or those with a shell structure can be used. The shell-like structure is determined by the order of addition of the individual monomers; The morphology of the polymers is also influenced by this order of addition.

The monomers for the production of the rubber part of the elastomers are only representative of acrylates such as n-butyl acrylate and 2-ethylhexyl acrylate, corresponding methacrylates, butadiene and isoprene and mixtures thereof. These monomers can be combined with other monomers such as styrene, acrylonitrile, vinyl ethers and other acrylates or methacrylic acid. ten such as methyl methacrylate, methyl acrylate, ethyl acrylate and propyl acrylate are copolymerized.

The soft or rubber phase (with a glass transition temperature of below 0 ° C) of the elastomers can represent the core, the outer shell or a middle shell (in the case of elastomers with more than two shells); in the case of multi-layer elastomers, several shells can also consist of a rubber phase.

If, in addition to the rubber phase, one or more hard components (with glass transition temperatures of more than 20 ° C) are involved in the construction of the elastomer, these are generally obtained by polymerizing styrene, acrylonitrile, methacrylonitrile, methyl methyl styrene, methyl styrene, Acrylic acid esters and methacrylic acid esters such as methyl acrylate, ethyl acrylate and methyl methacrylate are produced as main monomers. In addition, smaller proportions of further comonomers can also be used here.

In some cases it has proven advantageous to use emulsion polymers which have reactive groups on the surface. Such groups are e.g. Epoxy, carboxyl, latent carboxyl, amino or amide groups as well as functional groups by the use of monomers of the general formula

R ¹⁰ R ¹¹

CH ₂ = CXNCR ¹²

can be introduced

where the substituents can have the following meanings:

R ^{10 is} hydrogen or a C _r to C ₄ alkyl group,

R ^{11 is} hydrogen, a C to C ₈ alkyl group or an aryl group, in particular phenyl,

R ^{12 is} hydrogen, ad to C ₁₀ alkyl, a C ₆ to C ₂ aryl group or -OR ¹³

13

R is a C to C ₈ alkyl or C ₆ to C ₁₂ aryl group, which can optionally be substituted by O- or N-containing groups,

X is a chemical bond, a C _r to C ₁₀ alkylene or C ₆ -C ₁₂ arylene group or O

II

- c - Y

Y O-Z or NH-Z and

Z is a C 1 to C ₁₀ alkylene or C ₆ to C ₂ arylene group.

The graft monomers described in EP-A 208 187 are also suitable for introducing reactive groups on the surface.

Further examples include acrylamide, methacrylamide and substituted esters of acrylic acid or methacrylic acid such as (Nt-butylamino) ethyl methacrylate, (N, N-dimethylamino) ethyl acrylate, (N, N-dimethylamino) methyl acrylate and (N, N- Diethylamino) called ethyl acrylate.

The particles of the rubber phase can also be crosslinked. Monomers acting as crosslinking agents are, for example, buta-1,3-diene, divinylbenzene, diallyl phthalate and dihydrodicyclopentadienyl acrylate, and the compounds described in EP-A 50 265.

So-called graft-linking monomers can also be used, i.e. Monomers with two or more polymerizable double bonds, which react at different rates during the polymerization. Compounds are preferably used in which at least one reactive group polymerizes at about the same rate as the other monomers, while the other reactive group (or reactive groups) e.g. polymerizes much slower (polymerize). The different polymerization rates result in a certain proportion of unsaturated double bonds in the rubber. If a further phase is subsequently grafted onto such a rubber, the double bonds present in the rubber react at least partially with the graft monomers to form chemical bonds, i.e. the grafted phase is at least partially linked to the graft base via chemical bonds.

Examples of such graft-crosslinking monomers are monomers containing allyl groups, in particular allyl esters of ethylenically unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyifumarate, diallyl itaconate or the corresponding monoallyl compounds of these dicarboxylic acids. There are also a large number of other suitable graft-crosslinking monomers; for further details, reference is made here, for example, to US Pat. No. 4,148,846.

In general, the proportion of these crosslinking monomers in the impact-modifying polymer is up to 5% by weight, preferably not more than 3% by weight, based on the impact-modifying polymer. Some preferred emulsion polymers are listed below. First of all, there are graft polymers with a core and at least one outer shell that have the following structure:

These graft polymers, in particular ABS and / or ASA polymers in amounts of up to 40% by weight, are preferably used for impact modification of PBT, optionally in a mixture with up to 40% by weight of polyethylene terephthalate. Corresponding blend products are available under the trademark Ultradur®S (formerly Ultrablend®S from BASF AG).

Instead of graft polymers with a multi-layer structure, homogeneous, i.e. single-shell elastomers of buta-1,3-diene, isoprene and n-butyl acrylate or their copolymers are used. These products can also be produced by using crosslinking monomers or monomers with reactive groups.

Examples of preferred emulsion polymers are n-butyl acrylate / (meth) acrylic acid copolymers, n-butyl acrylate / glycidyl acrylate or n-butyl acrylate / glycidyl methacrylate copolymers, graft polymers with an inner core of n-butyl acrylate or based on butadiene and an outer shell the aforementioned copolymers and copolymers of ethylene with comonomers which provide reactive groups.

The elastomers described can also be made by other conventional methods, e.g. by suspension polymerization.

Silicone rubbers as described in DE-A 37 25 576, EP-A 235 690, DE-A 38 00 603 and EP-A 319 290 are also preferred.

Of course, mixtures of the rubber types listed above can also be used. Fibrous or particulate fillers D) are carbon fibers, glass fibers, glass spheres, amorphous silica, asbestos, calcium silicate, calcium metasilicate, magnesium carbonate, kaolin, chalk, powdered quartz, mica, barium sulfate and feldspar, which are present in amounts of up to 50% by weight. , in particular up to 40%.

Preferred mixing ratios with component B) are 40-70% by weight of component B) and 65 to 25% by weight of fillers D); preferred mixing ratios B) to D) are from 100: 1 to 2: 1.

Carbon fibers, aramid fibers and potassium titanate fibers may be mentioned as preferred fibrous fillers, glass fibers being particularly preferred as E-glass. These can be used as rovings or cut glass in the commercially available forms.

Mixtures of glass fibers D) with component B) in a ratio of 1: 100 to 1: 2 and preferably 1:10 to 1: 3 are particularly preferred.

The fibrous fillers can be surface-pretreated with a silane compound for better compatibility with the thermoplastic.

Suitable silane compounds are those of the general formula

(X- (CH2) _n ) k-Si (0-C _m H _2m + ι) ₂ -

in which the substituents have the following meaning:

X NH ₂ -, CH ₂ -CH-, HO-,

\ /

O

n is an integer from 2 to 10, preferably 3 to 4 m is an integer from 1 to 5, preferably 1 to 2 k is an integer from 1 to 3, preferably 1

Preferred silane compounds are aminopropyltrimethoxysilane, aminobutyltrimethoxysilane, aminopropyltriethoxysilane, aminobutyltriethoxysilane and the corresponding silanes which contain a glycidyl group as substituent X.

The silane compounds are generally used in amounts of 0.05 to 5, preferably 0.5 to 1.5 and in particular 0.8 to 1% by weight (based on E) for surface coating.

Acicular mineral fillers are also suitable. For the purposes of the invention, acicular mineral fillers are understood to be mineral fillers with a pronounced acicular character. An example is needle-shaped wollastonite. The mineral preferably has a UD (length diameter) ratio of 8: 1 to 35: 1, preferably 8: 1 to 11: 1. The mineral filler may optionally have been pretreated with the abovementioned silane compounds; however, pretreatment is not essential.

Kaolin, calcined kaolin, wollastonite, talc and chalk may be mentioned as further fillers.

As component D), the thermoplastic molding compositions according to the invention can contain customary processing aids such as stabilizers, oxidation retardants, agents against heat decomposition and decomposition by ultraviolet light, lubricants and mold release agents, colorants such as dyes and pigments, nucleating agents, plasticizers, etc.

Examples of oxidation retarders and heat stabilizers are sterically hindered phenols and / or phosphites, hydroquinones, aromatic secondary amines such as diphenylamines, various substituted representatives of these groups and their mixtures in concentrations of up to 1% by weight, based on the weight of the thermoplastic molding compositions.

Various substituted resorcinols, salicylates, benzotriazoles and benzophenones may be mentioned as UV stabilizers, which are generally used in amounts of up to 2% by weight, based on the molding composition.

Inorganic pigments such as titanium dioxide, ultramarine blue, iron oxide and carbon black, furthermore organic pigments such as phthalocyanines, quinacridones, perylenes and dyes such as nigrosine and anthraquinones can be added as colorants.

Sodium phenylphosphinate, aluminum oxide, silicon dioxide and, preferably, talc can be used as the nucleating agent.

Lubricants and mold release agents which are different from C) are usually used in amounts of up to 1% by weight. It is preferred to use long-chain fatty acids (e.g. stearic acid or behenic acid), their salts (e.g. Ca or Zn stearate) or montan waxes (mixtures of straight-chain, saturated carboxylic acids with chain lengths of 28 to 32 C atoms) as well as Ca or Na montanate and low molecular weight polyethylene or polypropylene waxes.

Examples of plasticizers are phthalic acid dioctyl ester, phthalic acid dibenzyl ester, phthalic acid butyl benzyl ester, hydrocarbon oils, N- (n-butyl) benzenesulfonamide.

The molding compositions according to the invention can also contain 0 to 2% by weight of fluorine-containing ethylene polymers. These are polymers of ethylene with a fluorine content of 55 to 76% by weight, preferably 70 to 76% by weight. Examples of these are polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymers or tetrafluoroethylene copolymers with smaller proportions (generally up to 50% by weight) of copolymerizable ethylenically unsaturated monomers. These are described, for example, by Schildknecht in "Vinyl and Related Polymers", Wiley-Verlag, 1952, pages 484 to 494 and by Wall in "Fluorpolymers" (Wiley Interscience, 1972).

These fluorine-containing ethylene polymers are homogeneously distributed in the molding compositions and preferably have a particle size d ₅₀ (number average) in the range from 0.05 to 10 μm, in particular from 0.1 to 5 μm. These small particle sizes can be achieved particularly preferably by using aqueous dispersions of fluorine-containing ethylene polymers and incorporating them into a polyester melt.

The thermoplastic molding compositions according to the invention can be produced by processes known per se, in which the starting components are mixed in conventional mixing devices such as screw extruders, Brabender mills or Banbury mills and then extruded. After the extrusion, the extrudate can be cooled and crushed. Individual components can also be premixed and then the remaining starting materials can be added individually and / or also mixed. The mixing temperatures are usually 230 to 290 ° C.

According to a further preferred procedure, components B) and optionally C) and / or D) can be mixed, made up and granulated with a polyester prepolymer. The granules obtained are then condensed in the solid phase under inert gas continuously or batchwise at a temperature below the melting point of component A) to the desired viscosity.

The thermoplastic molding compositions according to the invention are notable for good thermal conductivity and electrical insulation. The surfaces are smooth and versatile (printing, laser-inscribable). Printing / labeling using common methods, for example speed printing or inkjet labeling, is possible without any problems. Furthermore, the molding compositions according to the invention can be labeled using laser light, for example Nd: YAG lasers, in accordance with known methods.

In particular, the processing of the individual components (without clumping or caking) is possible without any problems despite the high filler content.

These are suitable for the production of fibers, foils and moldings of any kind, in particular for applications as cooling or heating elements. These applications are in particular heat sinks of all kinds of carrier plates for semiconductor chips, heat sinks for power chips, housings for electronic controls which contain heat-producing components; Lamp holders for halogen lamps in the low and high voltage range.

The preferred thermal conductivity is at least 0.8 W / mk, in particular 1 W / mk. Examples

Component A: polybutylene terephthalate with a viscosity number of 130 ml / g and a carboxyl end group content of 34 meq / kg (Ultradur® B 4520 from BASF AG) (VZ measured in 0.5% by weight solution of phenol / o-dichlorobenzene), 1: 1 mixture at 25 ° C., containing 0.65% by weight of pentaerythritol tetrastearate (component C), based on 100% by weight of A).

Component B1:

σ AI ₂ 0 ₃

Density: 3.98 g / cm ³ spec. BET surface area: 1.0 - 2.0 m ² / g

Na ₂ 0 content: 0.2-0.32% by weight d ₅₀ value: 2.0-4.5 mm d ₁₀ value: 0.5-2.0 μm

K value: 30 W / mK

Component B2:

a Al ₂ 0 ₃

Density: 3.98 g / cm ³ spec. BET surface area: 0.4 - 0.8 m ² / g Na ₂ 0 content: 0.1% by weight d ₅₀ value: 4.5 - 8.0 μm K value: 30 W / mK

Component D

Cut glass fibers with an average thickness of 10 μm

Production of molding compounds

Components A) to D) were mixed in a twin-screw extruder at 250 to 260 ° C. and extruded in a water bath. After granulation and drying, test specimens were injected and tested on an injection molding machine.

The MVR was determined in accordance with ISO 11 33, the thermal conductivity in accordance with DIN 52612 on shaped bodies (80 mm in diameter, 4 mm in thickness) had been determined beforehand for 24 hours in a standard climate of 23 ° C./50% atmospheric humidity. The ball indentation hardness was determined according to ISO 2039-1 on moldings (80 mm diameter, 4 mm thick). The compositions according to the invention and the results of the measurements are shown in the table.

Claims

claims

1. Containing thermoplastic molding compositions

A) 10 to 70 wt .-% of a thermoplastic polyester

B) 30 to 85% by weight of an aluminum oxide

D) 0 to 60% by weight of further additives,

the sum of the percentages by weight of components A) to D) being 100.

2. Thermoplastic molding compositions according to claim 1, containing as component B) at least one σ-aluminum oxide.

3. Thermoplastic molding compositions according to claims 1 or 2, in which component B) has an average particle size d ₅₀ of less than 20 microns.

4. Thermoplastic molding compositions according to claims 1 to 3 in which component B) has a density of 2.5 to 4.5 gm / cm ³ .

5. Thermoplastic molding compositions according to claims 1 to 4, in which component B) has a specific surface area according to BET (DIN 66132) of at least 0.38 m ² / g.

6. Thermoplastic molding compositions according to claims 1 to 5, in which component B) has a sodium oxide content of less than 0.4 wt .-%.

7. Thermoplastic molding compositions according to claims 1 to 6, in which component B) has a thermal conductivity K of at least 20 W / mK according to DIN 52612.

8. Use of the thermoplastic molding compositions according to claims 1 to 7 for the production of moldings of any kind, fibers and films.

9. Moldings obtainable from the thermoplastic molding compositions according to claims 1 to 7.

10. Shaped body according to claim 9, which have a thermal conductivity K according to DIN 52612 of at least 0.8 W / mK.

1. Electrically conductive and insulating molded body according to claims 9 or 10, characterized in that these are cooling or heating elements.