EP1080151A1 - Polyoxymethylene shaped bodies - Google Patents

Abstract

The invention relates to shaped bodies obtained by multicomponent injection moulding or multicomponent extrusion, and is characterised in that one part of the shaped body consists of a conductive polyoxymethylene composition A) whilst the other part consists of a non-conductive polyoxymethylene composition B).

Description

Moldings made of polyoxymethylenes

description

The invention relates to moldings obtainable by multi-component injection molding or multi-component extrusion processes, characterized in that part of the molding consists of a conductive polyoxymethylene composition A) and the other part consists of a non-conductive polyoxymethylene composition B).

Polyoxymethylene molding compositions containing carbon black include known from DE-A 196 380 36, EP-A 327 384, DE-A 40 07 766, EP-A 247 765 and EP-A 327 384.

Furthermore, commercially available products such as Ultraform ^® N2520 L (registered trademark of Ultraform GmbH) and Hostaform ^® C 9021 ELS (registered trademark of Hoechst AG) are equipped with the usual conductive or colored carbon black, which are well suited for antistatic equipment or for discharging static electricity.

The use of such molded parts are, for example, general treatises such as H.J. Mair, electrically conductive plastics, Hanser Verlag 1989, pp. 1 to 18 or R.G. Gilg, carbon black for conductive plastics, Kunststoffberater 22, p. 262 (1977) and 22, p. 312 (1977; S. Roth, HJ Mair, electrically conductive plastics, GAK, year 48 (volume 9), pp. 634-639 (1995).

In the cited literature, there is consistently seen as a disadvantage is ^¬ that carbon black in large amounts, the mechanical properties of POM adversely affected, since carbon black is an acidic additive and the POM matrix damaged.

The poorer mechanical properties have so far been compensated for by adding an impact modifier such as thermoplastic polyurethane (TPU). However, the soot accumulates predominantly in the elastomer phase, so that the volume resistance required for electrostatic painting or heating is not achieved.

For this reason, combined moldings made of metal and thermoplastic are used in heated moldings such as windscreen washer nozzles (see e.g. EP-B 353 643 or EP-A 724 992) due to the poorer mechanical properties. 2

Process for the production of molded articles from polyamide using different multi-component - injection molding technologies include known from R. Hagen, Kunststoffe 79 (1989) 1, pp. 72 to 76, and EP-A 393 409.

The object of the present invention was to provide moldings made of partially conductive polyoxymethylenes which have a requirement profile which can be varied for the respective application. The mechanics and chemical resistance, in particular to fuel, are to be improved, with the conductivity at least being maintained.

Accordingly, the moldings defined at the outset were found. Preferred embodiments can be found in the subclaims.

Surprisingly, in the case of a shaped body composed of a combination of non-conductive and conductive POM compositions, the chemical resistance is improved and the specific surface resistance is significantly reduced, i.e. the surface conductivity is significantly improved.

As component AI), the composition A) according to the invention contains molding compositions 70 to 99, preferably 75 to 97% by weight and in particular 75 to 94% by weight of a polyoxymethylene homo- or copolymer.

Such polymers are known per se to the person skilled in the art and are described in the literature.

In general, these polymers have at least 50 mol% of recurring units -CH ₂ O- in the main polymer chain.

The homopolymers are generally prepared by polymerizing formaldehyde or trioxane, preferably in the presence of suitable catalysts.

Within the scope of the invention is preferably polyoxymethylene copolymers Kom ^¬ component A, in particular those which in addition to the repeating units _-CH2O-, up to 50, preferably 0.1 to 20 and in particular from 0.3 to 10 mol% of recurring units 3

R ² R ³

IIOCC ( ⁵ ) n Rl R4

-wherein R ¹ to R ⁴ independently of one another are a hydrogen tom, a C 1 -C 4 -alkyl group or a halogen-substituted alkyl group with 1 to 4 C atoms and R ^{5 is} a -CH ₂ -, -CH ₂ 0-, a Ci-bis

C -Alkyl- or Ci- to C ₄ -haloalkyl substituted methylene group or a corresponding oxymethylene group and n has a value in the range from 0 to 3. These groups can advantageously be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula

R ² Rl c I 0

R ³ C (R ⁵ ) _n

R4

where R ¹ to R ⁵ and n have the meaning given above. For example, ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 1,3-dioxane, 1,3-dioxolane and 1,3-dioxepane may be mentioned as cyclic ethers and linear oligo- or polyformals such as polydioxolane or polydioxepane as comonomers.

Also suitable as component AI) are oxymethylene terpolymers which, for example, by reacting trioxane, one of the cyclic ethers described above with a third monomer, preferably bifunctional compounds of the formula

CH ₂ CH CH ₂ Z CH ₂ - CH- CH ₂

\. / \ V and / or

4 where Z is a chemical bond, -0-, -ORO- (R = Ci to Cs alkylene or C _{2 to} Cs cycloalkylene) are produced.

Preferred monomers of this type are ethylene diglycide, diglycidyl ether and diether from glycidylene and formaldehyde, dioxane or trioxane in a molar ratio of 2: 1, and diether from 2 mol of glycidyl compound and 1 mol of an aliphatic diol with 2 to 8 C-atoms such as for example the diglycidyl ethers of ethylene glycol, 1,4-butanediol, 1,3-butanediol, cyclobutane-1,3-diol, 1,2-propanediol and cyclohexane-1,4-diol, to name just a few examples.

Processes for the preparation of the homopolymers and copolymers described above are known to the person skilled in the art and are described in the literature, so that further details are unnecessary here.

The preferred polyoxymethylene copolymers have melting points of at least 150 ° C. and molecular weights (weight average) M _w in the range from 5000 to 200000, preferably from 7000 to 150,000.

End group-stabilized polyoxymethylene polymers which have C-C bonds at the chain ends are particularly preferred.

Products which contain a relatively high proportion (generally> 0.1% by weight) of thermally unstable proportions can in particular also be used as component AI).

As component A2), the compositions A) according to the invention contain 1 to 15, preferably 2 to 10 and in particular 5 to 8% by weight of carbon black with a pore volume (DBP dibutyl phthalate adsorption) according to DIN 53 601 of at least 350 ml / g 100 g, preferably at least 370 ml / 100 g.

The DBP adsorption rate is generally determined in accordance with DIN 53 601 or ASTM-D 2414 and represents a measure of the structure of the respective carbon black. Structure is the chaining of primary carbon black particles to form aggregates. To determine this parameter, 10 g of carbon black, which is placed in a kneader with measurable power transmission (plastograph), is added dropwise until dibutyl phthalate is added until the maximum torque (network point of the carbon black) is exceeded.

Component A2) preferably has a specific surface area according to BET (according to DIN 60 132 or ASTM D 3037) of at least 900, preferably 950 m ² / g and an iodine adsorption of (according to DIN 53 582 or ASTM-D 1510) of at least 950, preferably 1000 and in particular 1050 mg / g. 5

The average primary particle size is usually 10 to 50, preferably 25 to 35 nm.

Such types of carbon black are, for example, under the trade name Printex ^® XE2 (Degussa AG) or Ketjen Black EC DJ 600 (Akzo) available.

As component A3), the molding compositions which can be used according to the invention contain 0 to 2, preferably 10 ppm to 1.5 and in particular 0.001 to 1% by weight, based on the total weight of components AI) to A4), of an alkali and / or alkaline earth compound.

Generally, all alkaline earth and / or alkali metal cations can be used, with lithium, sodium, potassium and calcium cations being preferred.

According to the invention, alkali and / or alkaline earth compounds are to be understood as meaning those inorganic or organic salts which have an alkaline reaction in aqueous solution or suspensions.

Examples of inorganic salts are carbonates, hydrogen carbonates, hydroxides, oxides or phosphates, alkali carbonates such as potassium carbonate and sodium carbonate being particularly preferred.

Organic salts are, for example, alcoholates from C _{2 to} C ₁₂ alcohols, phenolates or salts of carboxylic acids with 2 to 12 C atoms, citrates, oxalates or tartrates being particularly preferred.

Alkali metal hydroxides, in particular potassium hydroxide and sodium hydroxide, which are preferably added in the form of an aqueous 10 to 70% strength solution, preferably 40 to 60% strength in the preparation of the POM molding compositions, are particularly preferred, it being possible to dose them together with the carbon black.

As component A4), the compositions A) according to the invention contain 0 to 15, preferably up to 10 and in particular up to 9% by weight of further additives.

The polyamides that can be used as components A4) are known per se. Semicrystalline or amorphous resins, as described, for example, in the Encyclopedia of Polymer Science and Engineering, Vol. 11, pp. 315 to 489, John Wiley & Sons, Inc. 1988, can be used, the melting point of the polyamide preferably being below 225 ° C, preferably below 215 ° C. 6

Examples include polyhexamethylene azelaic acid amide, poly hexamethylene sebacic acid amide, polyhexamethylene dodecanedioic acid amide, poly-11-aminoundecanoic acid amide and bis (p-aminocyclohexyl) methane dodecanoic acid diamide or those obtained by ring opening of lactams, e.g. or products obtained from polylaurine lactam. Polyamides based on terephthalic or isophthalic acid as the acid component and / or trimethylhexamethylene diamine or bis (p-aminocyclohexyl) propane as the diamine component and polyamide base resins which have been prepared by copolymerizing two or more of the abovementioned polymers or their components are also suitable.

Mixed polyamides based on caprolactam, hexamethylenediamine, p, p '-diaminodicyclohexylmethane and adipic acid may be mentioned as particularly suitable polyamides. An example of this is the product sold by BASF Aktiengesellschaft under the name Ultramid 1 C.

Other suitable polyamides are marketed by Du Pont under the name Elvamide.

The preparation of these polyamides is also described in the aforementioned document. The ratio of terminal amino groups to terminal acid groups can be controlled by varying the molar ratio of the starting compounds.

The proportion of the polyamide in the molding composition according to the invention is 0 to 2, preferably 0.005 to 1.8% by weight, preferably 0.04 to 1.6% by weight.

According to a preferred embodiment, the molding compositions can contain a melamine-formaldehyde condensate as nucleating agent A4). Suitable products are e.g. described in DE-A 25 40 207.

Suitable sterically hindered phenols (antioxidants) are in principle all compounds with a phenolic structure which have at least one sterically demanding group on the phenolic ring. For example, compounds of the formula are preferably used

R ² R ³

^H ° -

R ^l

in which mean:

R ¹ and R ^{2 are} an alkyl group, a substituted alkyl group or a substituted triazole group, where the radicals R ¹ and R ^{2 may be the} same or different and

R ^{3 is} an alkyl group, a substituted alkyl group, an alkoxy group or a substituted amino group.

Antioxidants of the type mentioned are described, for example, in DE-A 27 02 661 (US-A 4 360 617).

Another group of preferred sterically hindered phenols is derived from substituted benzene carboxylic acids, in particular from substituted benzene propionic acids.

Particularly preferred compounds from this class are compounds of the formula

0

CH ₂ CH ₂ "OR ⁶ -

wherein R ⁴ , R ⁵ , R ⁷ and R ⁸ independently of one another C 1 -C ₈ alkyl groups, which in turn can be substituted (at least one of them is a sterically demanding group) and R ^{6 is} a divalent aliphatic radical having 1 to 10 C atoms , which can also have C-0 bonds in the main chain. Preferred compounds corresponding to this formula

5i or

0 0

CH ₂ - CH ₂ - - CH ₂ - CH ₂ 0 - CH ₂ - CH ₂ 0 - CH ₂ CH ₂ 0 C - CH ₂ - -CH

CH ₃

(Irgano 245 from Ciba-Geigy) 03

0 0

CH ₂ - CH ₂ • 0 (CH ₂ ) ₆ - 0- -CH ₂ CH ₂

Irganox 259 from Ciba-Geigy) O

H β a eo

Examples include sterically hindered phenols:

2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 1,6-hexanediol - bis [3 - (3,5-di-tert-butyl -4-hydroxypheny1) propionate ], Pentaerythryl tetrakis [3 - (3,5-di-tert-butyl -4-hydroxy-phenyl) -propionate], distraryl-3,5-di-tert. -butyl-4-hydroxybenzyl-phosphonate, 2, 6, 7 -trioxa-1-phosphabicyclo- [2.2.2] oct-4-yl-methyl-3, 5-di-tert. -butyl-4-hydroxyhydrocinnamate, 3, 5-di-tert. -butyl-4-hydroxypheny1 - 3,5-distearyl-thiotriazylamine, 2- (2 '-hydroxy-3' -hydroxy-3 ', 5' -di-tert.-butylphenyl) -5-chlorobenzotriazole, 2, 6 -diet. -butyl -4-hydroxymethylphenol, 1,3,5-tri-methyl-2,4,4-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 4,4'-methylene -bis- (2, 6-di-tert-butylphenol), 3, 5-di-tert. -butyl -4-hydroxy-benzyl-dimethylamine and N, N '-hexamethylene-bis-3, 5-di- tert. -butyl-4-hydroxyhydrocinnamide.

Have proven to be particularly effective and are therefore preferably used 2, 2 '-methylene-bis- ((4-methyl-6-tert-butylphenyl), 1, 6-hexanediol-bis- [3, 5-di-tert -butyl-4-hydroxyphenyl) propionate (Irganox ^® 259), pentaerythrityl tetrakis [3- (3, 5-di-tert-butyl -4-hydroxypheny1) propionate] and the Irganox® described above 245 from Ciba Geigy, which is particularly well suited.

The antioxidants, which can be used individually or as mixtures, can be used in an amount of 0.05 to 2% by weight, preferably 0.1 to 1.0% by weight.

In some cases, sterically hindered phenols with no more than one sterically hindered group ortho to phenolic hydroxyl groups have proven to be particularly advantageous; especially when assessing the color stability of storage in diffuse light over long periods of time.

In some cases, the dispersibility of the polyamides used can be improved by using a polycondensation product consisting of 2,2-di (4-hydroxyphenyl) propane (bisphenol A) and epichlorohydrin.

Such condensation products of epichlorohydrin and bisphenol A are commercially available. Methods for their preparation are also known to the person skilled in the art. Commercial names of the polycondensates are Phenoxy ^® (from Union Carbide Corporation) and Epikote ^® (from Shell). The molecular weight 10 of the polycondensates can vary within wide limits; in principle, the types available on the market are all suitable.

Component A4) can also contain 0.002 to 2.0% by weight, preferably 0.005 to 0.5% by weight and in particular 0.01 to 0.3% by weight, of one or more alkaline earth metal silicates and / or alkaline earth metal glycerophosphates be included. Calcium and in particular magnesium have proven to be excellent as alkaline earth metals for the formation of the silicates and glycerophosphates. Magnesium glycerophosphate and / or are suitably used

Calcium silicate and preferably magnesium silicate, preference being given to earth, alkali silicates, in particular those represented by the formula

Me ^• x Si0 ^• n H0

are described in the mean

Me an alkaline earth metal, preferably calcium or especially magnesium,

x is a number from 1.4 to 10, preferably 1.4 to 6 and

n is a number equal to or greater than 0, preferably 0 to 8.

These compounds are advantageously used in finely ground form. Products with an average particle size of less than 100 μm, preferably less than 50 μm, are particularly well suited.

Compositions A) according to the invention may also contain further additives. Additives for trapping formaldehyde (formaldehyde scavenger), plasticizers, lubricants, adhesion promoters and light stabilizers are only mentioned here as examples. The proportion of such additives is generally in the range from 0.001 to 5% by weight.

Composition B) according to the invention is composed of

Bl) 20 to 100, preferably 20 to 80 and in particular

30 to 80% by weight of a polyoxymethylene homo- or copolymer, as already stated under component AI) and

B2) 0 to 80% by weight, preferably 0 to 50 and in particular 0 to 40% by weight of further additives, 11 where the sum of the percentages by weight of components B1) and B2) each gives 100%.

In principle, all compounds which are already listed above under component A4) come into consideration as component B2).

For example, by adding impact modifiers B2) or reinforcing materials B2), the composition B can be varied such that a property profile required for the particular application is achieved.

As reinforcing fillers B2) in amounts up to

50% by weight, preferably 1 to 40% by weight, may be mentioned, for example, potassium titanate whiskers, carbon and preferably glass fibers, the glass fibers being e.g. in the form of glass fabrics, mats, nonwovens and / or glass silk rovings or cut glass silk made from low-alkali E-glass with a diameter of 5 to 200 μm, preferably 8 to 50 μm, the fibrous fillers preferably being a medium one after being incorporated Have a length of 0.05 to 1 μm, in particular 0.1 to 0.5 μm.

Other suitable fillers are, for example, wollastonite, calcium carbonate, glass balls, quartz powder, silicon and boron nitride or mixtures of these fillers.

Preferred combinations of fillers are: wollastonite with glass fibers, with mixing ratios of 5: 1 to 1: 5 being preferred.

Other additives are, in amounts of up to 50, preferably 0 to 40,% by weight, impact-modifying polymers (also referred to below as rubber-elastic polymers or elastomers).

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, whereas 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-l, 5-diene and octa-l, 4-diene, 12 cyclic dienes such as cyclopentadiene, cyclohexadienes, cycloocadienes and dicyclopentadiene and alkenylnorbornenes 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.

The EPDM rubbers can also be grafted with other monomers, e.g. with glycidyl (meth) acrylates, (meth) acrylic acid esters and (meth) acrylamides.

Another group of preferred rubbers are copolymers of ethylene with esters of (meth) acrylic acid. In addition, the rubbers can also contain monomers containing epoxy groups. These monomers containing epoxy groups are preferably incorporated into the rubber by adding monomers of general formulas I or II containing epoxy groups to the monomer mixture

CHR8 = CH— (CH ₂ ) _m - O— (CHR ⁷ ) _g - CH-CHR6 ^(I)

CH ₂ = CR ¹⁰ - COO— ⁽ —CH ₂ ) p — CH — CHR ⁹ (n:

\ /

O

wherein R ⁶ - R ^{10 represent} hydrogen or alkyl groups with 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 ⁶ to R ^{8 are} preferably hydrogen, where m is 0 or 1 and g is 1. The corresponding compounds are allyl glycidyl ether and vinyl glycidyl ether.

Preferred compounds of the formula II are epoxy group-containing esters of acrylic acid and / or methacrylic acid, such as glycidyl acrylate and glycidyl methacrylate.

The copolymers advantageously consist of 50 to 98% by weight of ethylene, 0 to 20% by weight of monomers containing epoxy groups and the remaining amount of (meth) acrylic acid esters. 13

Copolymers of are particularly preferred

50 to 98, in particular 55 to 95% by weight of ethylene, in particular 0.3 to 20% by weight of glycidyl acrylate and / or

0 to 40, in particular 0.1 to 20 wt .-% glycidyl methacrylate, and

1 to 50, 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 may be prepared by processes known per se, preferably by random copolymerization temperature under high pressure and elevated ^¬ Tem. 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.

Representative here are as monomers for the production of the rubber part of the elastomers 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 e.g. Styrene, acrylonitrile, vinyl ethers and other acrylates or methacrylates such as methyl methacrylate, methyl acrylate, ethyl acrylate and propyl acrylate can be copolymerized.

The soft or rubber phase (with a glass transition temperature below 0 ° C) of the elastomers can the core, the outer shell or a middle shell (in the case of elastomers with more than two 14 shell structure); 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, -α-methylstyrene, p-methylstyrene, Acrylic acid esters and methacrylic acid esters such as methyl acrylate, ethyl acrylate and methyl methacrylate are produced as the main monomers. In addition, smaller proportions of further comonomers can also be used here.

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

_R 15 _R 16 | |

CH ₂ = C-X-N-C-R ¹⁷

can be introduced

where the substituents can have the following meanings:

R ^{15 is} hydrogen or a C 1 -C 4 -alkyl group,

R ^{16 is} hydrogen, a C 1 -C 4 -alkyl group or an aryl group, in particular phenyl,

R ^{17 is} hydrogen, a -C ~ to Cio-alkyl, a Cξ to Cι aryl group or -ORis

R ^{18 is} a -C ~ to Cs-alkyl or C ₆ - to -C ₂ -aryl group, which can optionally be substituted with 0- or N-containing groups,

X is a chemical bond, a C ~ to Cio alkylene or C ₆ -C ₂ arylene group or 15

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-diethyl) * called amino) 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 approximately the same rate as the other monomers, while the other reactive group (or reactive groups) e.g. polymerizes much slower (polymerize). The different polymerization speeds 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 graft linking monomers are allyl-containing monomers, in particular allyl esters of ethylenically unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate, diallyl itaconate and the entspre ^¬ sponding 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 component D) is up to 5% by weight, preferably not more than 3% by weight, based on D). 16

Some preferred emulsion polymers are listed below. First of all, graft polymers with a core and at least one outer shell have the following structure:

Monomers for the core Monomers for the shell

Buta-1, 3-diene, isoprene, styrene, acrylonitrile, (meth) - n-butyl acrylate, ethylhexyl acrylates, optionally with acrylate or mixtures thereof, reactive groups as described here, optionally together with crosslinking ones Monomers

Instead of graft polymers with a multi-layer structure, homogeneous, i.e. single-shell elastomers

Buta-1, 3-diene, isoprene and n-butyl acrylate or their copolymers can be used. These products can also be prepared by using crosslinking monomers or monomers with reactive groups.

The described elastomers D) can also be made according to other conventional ones

Processes, e.g. by suspension polymerization.

Thermoplastic polyurethanes such as are described, for example, in EP-A 115 846 may be mentioned as further suitable elastomers.

Of course, mixtures of the rubber types listed above can also be used.

For coloring, the compositions B) can contain inorganic and organic colorants, which are usually present in an amount of 0.01 to 10% by weight.

The thermoplastic compositions A) and B) according to the invention are produced by mixing the components in a manner known per se, which is why detailed information is unnecessary here. The components are advantageously mixed in an extruder.

The granules of the compositions A) and B) are then processed by means of multi-component injection molding or multi-component extrusion processes to give the moldings according to the invention. Suitable methods are known to the person skilled in the art and, for example, in 17 of DE-A 40 41 799, DE-A 40 32 499, DE-A 42 24 171 and DE-A 43 30 451.

The molded body can consist of layers of A) and B) arranged one above the other as well as a core of A) or B) which is overmolded with A) or B).

It is also possible to produce moldings with limited contact areas of compositions A) and B), which are obtainable on the basis of the processes described in EP-A 393 409.

For some applications (e.g. hoses) it may be necessary to change from e.g. To design a hose made of rubber-modified composition B) to have composition A) so that the "soft" hose is fluidly connected to a "hard" hose.

The moldings according to the invention are notable for good chemical resistance and improved surface conductivity. They are therefore suitable for applications as

Components for electrostatic painting

heated components in the automotive sector (headlight and windshield washer nozzles, heated exterior mirrors or door handles and door locks, heated diesel filters)

Heating or heating plates

- Aquarium or terrarium heaters

Components in the automotive fuel sector where static electricity has to be discharged (parts from the filler neck, the petrol pump, installation parts in the tank, etc.)

Parts of spinning machines (thread guides)

Parts for office furniture (swivel chairs, castors, guide bushes)

- Parts on fuel dispensers (deflection rollers)

Parts for electronic components that are stat. Electricity must be protected 18th

Transport chain links

Printing rollers, laser printers, copiers, offset printers.

Examples

The following components were used for composition A).

Component AI)

Polyoxymethylene copolymer from approx. 97% by weight trioxane and approx. 3% by weight butanediol formal. The product still contained approximately 5% by weight of unreacted trioxane and 5% by weight of thermally unstable components. After the thermally unstable components had broken down, the copolymer had a melt index of 25 ml / 10 min at 190 ° C. and 2.16 N, in accordance with ISO 1133.

Component A2)

Carbon black with a specific surface according to BET (according to DIN 66 132 of 950 m ² / g, DBP adsorption according to DIN 53 601 of 380 mg / g, and an iodine adsorption according to DIN 53 582 of 1075 mg / g.

(Printex ^® XE2, Degussa AG)

Component A3)

Sodium hydroxide (dosed as a 50% by weight aqueous solution)

Component A4a corresponded to component B2a component A4b corresponded to component B2b component A4c corresponded to component B2c component A4d corresponded to component B2d

For the compositions B) The following components were introduced ^¬ sets:

example 1

Bla: Polyoxymethylene copolymer from approx. 97% by weight trioxane and approx. 3% by weight butanediol formal. The product still contained unge ^¬ ferry 5 wt .-% of unconverted trioxane and 5 wt .-% ther ^¬ mixing unstable components. After the thermally unstable portions had broken down, the copolymer had a melt index of 7.5 ml / 10 min at 190 ° C. and 2.16 N, in accordance with ISO 1133. 19

B2a: polyamide with a molecular weight of 3000, made from 37% by weight ε-caprolactam, 63% by weight of an equimolar mixture of adipic acid and hexamethylenediamine, using propionic acid as a regulator.

B2b: Irganox ^® 245 (Ciba -Geigy AG):

-CH ₂ CH ₂ —O CH ₂ -

B2c: Synthetic Mg silicate (Ambosol ^® from Societe Nobel, Bozel, Puteaux) with the following properties

MgO content:> 14.8% by weight

Si0 content:> 59% by weight

Si0 ₂ : MgO ratio: 2.7 mol / mol

Bulk density: 20 to 30 g / 100 ml

Loss on ignition: <25% by weight

B2d: melamine-formaldehyde condensate according to Example 1 of DE-A 25 40 207.

Example 2

Blb: Polyoxymethylene copolymer from approx. 97% by weight trioxane and approx. 3% by weight butanediol formal. The product contained about 5 percent still -.% Of unconverted trioxane and 5 wt -.% Thermally stable in ^¬ shares. After the thermally unstable portions had broken down, the copolymer had a melt index of 11 ml / 10 min at 190 ° C. and 2.16 N, in accordance with ISO 1133.

B2e: A thermoplastic polyurethane prepared by imple ^¬ wetting of 4, 4 'diphenylmethane diisocyanate, 1, 4-butanediol-adipate and poly- 1, 4-butanediol having a Shore A hardness of 85th

Example 3

Bla: Polyoxymethylene copolymer from approx. 97% by weight trioxane and approx. 3% by weight butanediol formal. The product still contained unge ^¬ ferry 5 wt -.% Of unconverted trioxane and 5 wt -.% Of thermally unstable fractions. After dismantling the thermally unstable 20th

The copolymer had a melt index of 7.5 ml / 10 min at 190 ° C. and 2.16 N, in accordance with ISO 1133.

B2f: glass fibers with an average diameter of 10 μm.

Preparation of compositions A) and B)

The components AI to A3 and the respective components B1 and B2 were introduced in a twin-screw extruder with a degassing device and melted at 230 ° C., degassed in a homogenized manner and pressed out as a strand, cooled and granulated.

Plates with the dimensions 110 x 110 x 4 mm were sprayed on a 2-component injection molding machine (Klöckner Feromatik FM 160 machine with monosandwich device). For comparative example 1, the plate consisted of components AI) to A3).

For Examples 1 to 3 according to the invention, plates of the same size were injection molded with the aid of the monosandwich device, which contained composition A) in the outer layer and the core of the plate consisted of the respective composition B).

The following tests were carried out on the plates:

The layer thicknesses obtained were determined by measuring after the panels had been sawn open in the middle (mean values from several measurements or from the two outer layers of one panel each).

The spec. Surface resistance according to IEC 93 and the change in thickness after storage in hot petrol (Haltermann test fuel CEC-RF 08 A 85, 60 ° C, 1000 h) were measured. The impact strength according to ISO 179 leU and the bending modulus according to ISO 178 were also determined on sawn-out test specimens.

The liability of the individual layers to one another is magnificent P ^¬ net. So there was no detachment even after a longer heat exchange test (between -40 ° C over 24 h, and 100 ° C over 24 h, a total of 21 cycles) and after the petrol storage.

The compositions of the molding compositions and the results of the measurements can be found in the table. Table vo

Oil w

Combination in wt.% Layer - impact-bending spec. Above the thickness, tough module area change resistance after

Fuel storage

ISO 179 ISO 178 IEC 93 * leU mm kJ / m ² MPa Ohm%

IV 91.374 7 A2 0.7 A3 0.37 0.32 0.046 0.19 3.98 8.62 3710 500 2.78 AI A4a A4b A4c A4d

1 core 99.36 0.04 0.35 0.05 0.2 2.06 10.45 3530 200 0.31

Bla B2a B2b B2c B2d tυ case 91.374 7 A2 0.7 A3 0.37 0.32 0.046 0.19 0.97 AI A4a A4b A4c A4d

2 core 79.488 20 ble 0.032 0.28 0.04 0.16 2.48 8.24 3120 200 0.62 blb B2a B2b B2c B2d shell 91.374 7 A2 0.7 A3 0.37 0.32 0.046 0.19 0 , 76 AI A4a A4b A4c A4d

3 core 74.522 25 B2f 0.03 0.26 0.38 0.15 2.41 11.35 4340 200 0.39 Bla B2a B2b B2c B2d sleeve 91.374 7 A2 0.7 A3 0.37 0.32 0.046 0, 19 0.77 AI A4a A4b A4c A4d O

H

V = for comparison * 1000 h at 60 ° C, Haltermann CEC-RF 08 A85 "

VO o * -> o o *.

Claims

22 Patent claims

1. Shaped body, obtainable by multi-component injection molding or multi-component extrusion process, characterized in that part of the shaped body consists of a conductive polyoxymethylene composition A) and the other part of a non-conductive polyoxymethylene composition B).

2. Shaped body according to claim 1, characterized in that the composition A) is composed of

AI) 70 to 99% by weight of a polyoxymethylene homo- or copolymer

A2) 1 to 15% by weight of carbon black with a pore volume (DBP absorption) according to DIN 53601 of at least 350 ml / 100 g

A3) 0 to 2% by weight of an alkali or alkaline earth compound or mixtures thereof,

A4) 0 to 15% by weight of further additives,

where the sum of the weight percentages of components AI to A4) gives 100% in each case.

3. Shaped body according to claim 1 or 2, characterized in that the composition B) is composed of

B1) 20 to 100% by weight of a polyoxymethylene homo- or copolymer and

B2) 0 to 80% by weight of further additives,

the sum of the percentages by weight of components B1) and B2) in each case being 100%.

4. Shaped body according to claims 1 to 3, characterized in that the carbon black A2) has a specific surface according to BET (according to DIN 66132 of at least 900 m ² / g.

5. Shaped body according to claims 1 to 4, characterized in that the carbon black A2) has an iodine adsorption (according to DIN 53582) of at least 950 mg / g. 23

6. Shaped body according to claims 1 to 5, characterized in ^¬ net that as component A3) an alkali metal hydroxide or alkali metal - carbonate or mixtures thereof is used.