Stabilized thermoplastic partly aromatic polyamide moulding compounds.

The invention relates to thermoplastic molding compositions containing<ul id="ul0001" list-style="none"><li>A) 40-99.9% by weight of a partially aromatic partially crystalline copolyamide with a triamine content of less than 0.5% by weight<ul id="ul0002" list-style="none"><li>(A₁) 20-90% by weight of units derived from terephthalic acid and hexamethylmediamine,</li><li>(A₂) 0 - 50 wt .-% units derived from ε-caprolactam</li><li>(A₃) 0 - 80 wt .-% units derived from adipic acid and hexamethylenediamine,</li><li>(A₄) 0 - 40 wt .-% of other polyamide-forming monomers</li></ul> wherein the proportion of components (A₂) or (A₃) or (A₄) or mixtures thereof is at least 10% by weight,</li><li>(B) 0.1-2% by weight of at least one aromatic, secondary amine and</li><li>(C) 100-2000 ppm of at least one phosphorus-containing inorganic acid or its derivatives,</li></ul> where the content of component C) relates to the total amount of components A) and B), as well as beyond<ul id="ul0003" list-style="none"><li>(D) 0-59.9% by weight of a fibrous or particulate filler or a mixture thereof,</li><li>(E) 0-30% by weight of a rubbery polymer.</li></ul>

In addition, the invention relates to the use of such partially aromatic copolyamides for the production of fibers, films and moldings and the moldings obtainable from these partially aromatic copolyamides.

The stabilization of polyamides against oxidative and thermal degradation largely determines the possible uses of these polymers. Most of the time, these stabilization systems achieve adequate light protection at the same time.

Stabilizers based on copper iodide and potassium iodide for partially crystalline aliphatic polyamides are known from EP-A 281 691 and JP-A 63/142059 and DE-A 2 643 204 and DE-A 2 516 565.

Another possibility for stabilizing these partially crystalline aliphatic polyamides with sterically hindered phenols is known from DE-A 2 522 833. The combination of these phenols with other compounds is known from the following documents: DE-A 2 158 014 (phosphorus-containing compounds) and NL-A 8 602 807 (aromatic amine compounds).

From GB-A 1 030 363 nitrogen compounds in combination with transition metal amine complexes are known as a stabilization system for partially crystalline, aliphatic polyamides.

In addition, JP-A 63/105 057 discloses a stabilization system for partially aromatic but amorphous polyamides composed of a copper compound and phenolic or phosphorus-containing compounds, optionally with thioethers and amine compounds.

Furthermore, a stabilizer combination of an aromatic amine and a phosphorus-containing compound is known from CA-A 963 594 for partially crystalline aliphatic polyamides.

Semi-aromatic and semi-crystalline copolyamides have the advantage that they have a higher heat resistance and must be processed accordingly at higher temperatures. In this respect, these polyamides are mostly used where a high continuous use temperature in air is required (e.g. electrical sector).

However, the stabilizers known hitherto cannot be used for these polyamides, since e.g. B. copper compounds catalyze the degradation of polyamides during processing. Phenolic antioxidants are also unsuitable, since these compounds decompose when processed in an extruder at high temperatures.

In addition, only a small part of the starting amount remains in the molding composition itself, since these compounds are too volatile at the processing temperatures customary for partially aromatic copolyamides.

Aromatic amine compounds generally have the disadvantage that relatively high amounts are required to achieve effective stabilization, so that their use is not economical. In addition, they deteriorate the mechanical properties of the polyamide molded articles.

In addition, there is the problem with partially aromatic, partially crystalline copolyamides that oxidative and thermal stabilization are not coupled with adequate light protection, since the aromatic components drastically impair the light resistance.

The object of the present invention was therefore to provide a stabilization system for partially aromatic, partially crystalline copolyamides, which ensures good thermal and oxidative stabilization at the high processing temperatures.

Accordingly, the molding compositions defined at the outset were found. Preferred molding compositions of this type can be found in the subclaims.

As component A), the thermoplastic molding compositions according to the invention contain 40 to 99.9, preferably 50 to 99.5 and in particular 70 to 99.7% by weight of a partially aromatic, partially crystalline copolyamide with a triamine content of less than 0.5% by weight, preferably less than 0.3% by weight, composed of:<ul id="ul0004" list-style="none"><li>A₁) 20-90% by weight of units derived from terephthalic acid and hexamethylenediamine,</li><li>A₂) 0 - 50 wt .-% units derived from ε-caprolactam and</li><li>A₃) 0 - 80 wt .-% units derived from adipic acid and hexamethylenediamine,</li><li>A₄) 0 to 40% by weight of further polyamide-forming monomers,</li></ul> wherein the proportion of component (A₂) or (A₃) or (A₄) or mixtures thereof is at least 10 wt .-%.

The component A₁) contains 20 - 90 wt .-% units derived from terephthalic acid and hexamethylenediamine.

In addition to the units derived from terephthalic acid and hexamethylenediamine, the copolyamides contain units derived from ε-caprolactam and / or units derived from adipic acid and hexamethylenediamine and / or units derived from other polyamide-forming monomers.

The proportion of units derived from ε-caprolactam is a maximum of 50% by weight, preferably 20 to 50% by weight, in particular 25 to 40% by weight, while the proportion of units derived from adipic acid and hexamethylene diamine derive, is up to 80 wt .-%, preferably 30 to 75 wt .-% and in particular 35 to 60 wt .-%.

The copolyamides can also contain units of ε-caprolactam as well as units of adipic acid and hexamethylenediamine; in this case it is advantageous if the proportion of units which are free from aromatic groups is at least 10% by weight, preferably at least 20% by weight. The ratio of the units derived from ε-caprolactam and from adipic acid and hexamethylene diamine is not subject to any particular restriction.

Preferred are copolyamides whose composition in the three-substance diagram lies within the pentagon defined by corner points X₁ to X₁, the points X₁ to X₅ being defined as follows:<dl id="dl0001"><dt>X₁</dt><dd>40 % By weight units A₁) 60% by weight of units A₃)</dd><dt>X₂</dt><dd>60 % By weight units A₁) 40% by weight of units A₃)</dd><dt>X₃</dt><dd>80 % By weight units A₁) 5% by weight of units A₂) 15% by weight of units A₃)</dd><dt>X₄</dt><dd>80 % By weight units A₁) 20% by weight of units A₂)</dd><dt>X₅</dt><dd>50 % By weight units A₁) 50% by weight of units A₂)</dd></dl> The pentagon defined by these points is shown in a three-substance diagram in the figure.

Polyamides with 50 to 80, in particular 60 to 75,% by weight units derived from terephthalic acid and hexamethylenediamine (units A 1) and 20 to 50, preferably 25 to 40,% by weight units have proven to be particularly advantageous for many applications. which are derived from ε-caprolactam (units A₂)).

In addition to the units A₁) to A₃) described above, the partially aromatic copolyamides can contain up to 40, preferably 10-30% by weight and in particular 20-30% by weight of further polyamide-forming monomers A₄); as they are known from other polyamides.

Aromatic dicarboxylic acids A₄) preferably have 8 to 16 carbon atoms. Suitable aromatic dicarboxylic acids are, for example, isophthalic acid, substituted terephthalic and isophthalic acids such as 3-t-butylisophthalic acid, polynuclear dicarboxylic acids, for example 4,4'- and 3,3'-diphenyldicarboxylic acid, 4,4'- and 3,3'-diphenylmethane dicarboxylic acid, 4 , 4'- and 3,3'-diphenylsulfone dicarboxylic acid, 1,4- or 2,6-naphthalene dicarboxylic acid, phenoxy terephthalic acid, isophthalic acid being particularly preferred.

Further polyamide-forming monomers A₄) can be derived from dicarboxylic acids with 4 to 16 carbon atoms and aliphatic or cycloaliphatic diamines with 4 to 16 carbon atoms and from aminocarboxylic acids or corresponding lactams with 7 to 12 carbon atoms. Suitable monomers of these types here are only suberic acid, azelaic acid or sebacic acid as representatives of the aliphatic dicarboxylic acids, 1,4-butanediamine, 1,5-pentanediamine, piperazine, 4,4'-diaminodicyclohexylmethane, 2,2- (4,4'- Diaminodicyclohexyl) propane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane as representatives of diamines and capryllactam, enanthlactam, ω-aminoundecanoic acid and laurolactam as representatives of lactams or aminocarboxylic acids.

The following compositions of component (A) are particularly preferred:<dl id="dl0002"><dt>A₁) 65 to 85% by weight</dt><dd>Units derived from terephthalic acid and hexamethylenediamine and</dd><dt>A₄) 15 to 35% by weight</dt><dd>Units derived from isophthalic acid and hexamethylenediamine</dd></dl>    or<dl id="dl0003"><dt>A₁) 50 to 70% by weight</dt><dd>Units derived from terephthalic acid and hexamethylenediamine and</dd><dt>A₃) 10 to 20 wt .-%</dt><dd>Units derived from adipic acid and hexamethylenediamine and</dd><dt>A₄) 20 to 30% by weight</dt><dd>Units derived from isophthalic acid and hexamethylenediamine</dd></dl> If component (A₄) contains 4,4'-substituted symmetric dicarboxylic acids in which the carboxyl groups are in the para position, it is advisable to use these with (A₁) and (A₂) or (A₁) and (A₃) as ternary copolyamides to build up, otherwise the copolyamide has too high a melting point and only melts with decomposition, which is not desirable.

Furthermore, those partially aromatic copolyamides have proven to be particularly advantageous whose triamine content is less than 0.5, preferably less than 0.3,% by weight.

Partially aromatic copolyamides produced by most known processes (cf. US Pat. No. 4,603,166) have triamine contents which are above 0.5% by weight, which leads to a deterioration in product quality and to problems in continuous production. The diamine which causes these problems is, in particular, the dihexamethylene triamine which is formed from the hexamethylene diamine used in the preparation.

Copolyamides with a low triamine content, with the same solution viscosity, have lower melt viscosities compared to products of the same composition, which have a higher triamine content. This significantly improves both processability and product properties.

The melting points of the partially aromatic copolyamides are in the range from 270 ° C. to 325 ° C., preferably from 280 to 310 ° C., this high melting point also with a high glass transition temperature of generally more than 75, in particular more than 85 ° C. (in dry state).

Binary copolyamides based on terephthalic acid, hexamethylene diamine and ε-caprolactam have a melting point in the range of 300 ° C and (in the dry state) a glass transition temperature of about 70% by weight of units derived from terephthalic acid and hexamethylene diamine more than 110 ° C.

Binary copolyamides based on terephthalic acid, adipic acid and hexamethylenediamine reach melting points of 300 ° C and more even at lower contents of about 55% by weight of units of terephthalic acid and hexamethylenediamine (HMD), whereby the glass transition temperature is not quite as high as that of binary ones Copolyamides which contain ε-caprolactam instead of adipic acid or adipic acid / HMD.

In the case of the partially aromatic copolyamides, those which have a degree of crystallinity&gt; 10%, preferably&gt; 15% and in particular&gt; 20% are to be understood according to the invention.

The degree of crystallinity is a measure of the proportion of crystalline fragments in the copolyamide and is determined by X-ray diffraction.

The preferred partially aromatic copolyamides with a low triamine content can be prepared by the processes described in EP-A 129 195 and 129 196.

According to these processes, an aqueous solution of the monomers, ie in this case the monomers which form the units A₁) to A₄), is heated to a temperature of 250 to 300 ° C. under elevated pressure with simultaneous evaporation of water and formation of a prepolymer, the prepolymers and steam are then separated continuously, the steam is rectified and the diamines carried back are returned. Finally, the prepolymer is passed into a polycondensation zone and polycondensed under an excess pressure of 1 to 10 bar and a temperature of 250 to 300 ° C. It is essential in the process that the aqueous salt solution is heated under an excess pressure of 1 to 10 bar within a dwell time of less than 60 seconds, the degree of conversion advantageously emerging at least 93% and the water content of the prepolymer at most 7% when leaving the evaporator zone. -%.

These short dwell times largely prevent the formation of triamines.

The aqueous solutions used generally have a monomer content of 30 to 70% by weight, in particular 40 to 65% by weight.

The aqueous salt solution is advantageously passed continuously at a temperature of 50 to 100 ° C into an evaporator zone, where the aqueous salt solution is heated to a temperature of 250 to 330 ° C under an excess pressure of 1 to 10, preferably 2 to 6 bar. It is understood that the temperature used is above the melting point of the particular polyamide to be produced.

As already mentioned, it is essential that the residence time in the evaporator zone is a maximum of 60 seconds, preferably 10 to 55 seconds and in particular 10 to 40 seconds.

The conversion on leaving the evaporator zone is at least 93, preferably 95 to 98% and the water content is preferably in the range from 2 to 5, in particular 1 to 3,% by weight.

Furthermore, it has proven to be advantageous to pass the mixture of prepolymers and steam through a tubular mass transfer zone, which is provided with internals, before the phases are separated immediately after the evaporator zone. The temperatures and pressure conditions used in the evaporator zone are observed. The internals, for example fillers such as Raschig rings, metal rings or in particular fillers made of wire mesh, produce a large surface. As a result, the phases, ie Prepolymer and vapor, intimately contacted. This causes the amount of diamine released with water vapor to be significantly reduced. As a rule, a residence time of 1 to 15 minutes is maintained in the mass transfer zone. The mass transfer zone is advantageously designed as a tube bundle.

The two-phase mixture of steam and prepolymers emerging from the evaporator zone or mass transfer zone is separated. The separation usually takes place automatically due to the physical differences in a vessel, the lower part of the vessel advantageously being designed as a polymerization zone. The vapors released essentially consist of water vapor and diamines, which were released when the water evaporated. These vapors are passed into a column and rectified. Suitable columns are, for example, packed columns, bubble plate columns or sieve plate columns with 5 to 15 theoretical plates. The column is advantageously operated under the same pressure conditions as the evaporator zone. The diamines contained in the vapors are separated off and returned to the evaporator zone. It is also possible to feed the diamines to the subsequent polymerization zone. The rectified water vapor obtained is removed at the top of the column.

The prepolymer obtained, which, depending on its degree of conversion, consists essentially of low molecular weight polyamide and any remaining amounts of unreacted salts and generally has a relative viscosity of 1.2 to 1.7, is passed into a polymerization zone. In the polymerization zone, the melt obtained is polycondensed at a temperature of 250 to 330 ° C., in particular 270 to 310 ° C., and under an overpressure of 1 to 10 bar, in particular 2 to 6 bar. The vapors liberated here are advantageously rectified in the column together with the abovementioned vapors; a residence time of 5 to 30 minutes is preferably maintained in the polycondensation zone. The polyamide thus obtained, which generally has a relative viscosity of 1.2 to 2.3, is continuously removed from the condensation zone.

According to a preferred method of operation, the polyamide thus obtained is passed through a discharge zone in a molten state, with simultaneous removal of the residual water contained in the melt. Suitable discharge zones are, for example, degassing extruders. The melt thus freed from water is then poured into strands and granulated. The granules obtained are advantageously in the solid phase by means of superheated steam at a temperature below the melting point, for example from 170 to 240 ° C, condensed to the desired viscosity. Advantageously, the steam generated at the top of the column is used.

The relative viscosity, measured in 1 wt .-% solution in 96 wt .-% H₂SO₄ at 23 ° C, is generally after the solid phase post-condensation in the range from 2.2 to 5.0, preferably from 2.3 to 4.5 .

According to another preferred mode of operation, the polyamide melt discharged from the polycondensation zone is passed into a further polycondensation zone, where it is condensed to the desired viscosity with continuous formation of new surfaces at a temperature of 285 to 310 ° C., advantageously under reduced pressure, for example from 1 to 500 mbar . Suitable devices are known as finishers.

Another method which is similar to that described above is described in EP-A 129 196; for further details, reference is made to the writing.

Mixtures of different copolyamides can also be used as component A), the mixing ratio being arbitrary.

As component B), the molding compositions according to the invention contain at least one aromatic secondary amine in amounts of 0.1 to 2, preferably 0.5 to 1.5 and in particular 0.7 to 1% by weight, according to general formula I:<chemistry id="chem0001" num="0001"><img file="EP0509282A2_D0001.tif" /></chemistry> in which<dl id="dl0004"><dt>m, n =</dt><dd>0 or 1</dd><dt>A and B =</dt><dd>tertiary carbon atom substituted by C₁-C₄-alkyl or phenyl</dd><dt>R1, R2 =</dt><dd>Hydrogen or a C₁-C₆ alkyl group in the ortho or para position, which may optionally be substituted by 1 to 3 phenyl radicals, halogen, carboxyl group or a transition metal salt of this carboxyl group and</dd><dt>R³, R⁴ =</dt><dd>Hydrogen or a methyl radical in the ortho or para position when m plus n is 1 or a tertiary C₃-C₉ alkyl group in the ortho or para position, which can optionally be substituted by 1 to 3 phenyl radicals if m plus n represents 0 or 1,</dd></dl> mean.

Preferred radicals A or B are symmetrically substituted tertiary carbon atoms, with dimethyl-substituted tertiary carbon being particularly preferred. Also preferred are tertiary carbons which have 1 to 3 phenyl groups as substituents.

Preferred radicals R 1 or R 2 are para t-butyl or tetramethyl-substituted n-butyl, where the methyl groups can preferably be replaced by 1 to 3 phenyl groups. Preferred halogens are chlorine and bromine.

Preferred radicals R³ or R⁴ are for m plus n = 2 hydrogen, and for m plus n = 0 or 1, a t-butyl radical in the ortho or para position, which can in particular be substituted by 1 to 3 phenyl radicals.

Examples of secondary aromatic amines B) are 4'4'-bis (α, α'-tertiary octyl) diphenylamine 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 4,4'-bis (α-methylbenzhydryl) diphenylamine 4- (1,1,3,3-tetramethylbutyl) 4'-triphenylmethyldiphenylamine 4,4'-bis (α, α-p-trimethylbenzyl) diphenylamine 2,4,4'-tris (α, α-dimethylbenzyl) diphenylamine 2,2'-dibromo, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 4'4'-bis (α, α-dimethylbenzyl) -2-carboxydiphenylamine-nickel-4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2-sec-butyl-4,4'-bis (α, α-dimethylbenzyl) diphenylamine 4,4'-bis (α, α-dimethylbenzyl) -2- (α-methylheptyl) diphenylamine 2- (α-methylpentyl) 4,4'-ditrityldiphenylamine 4-α, α-dimethylbenzyl-4'-isopropoxydiphenylamine 2- (α-methylheptyl) -4 '- (α, α-dimethylbenzyl) diphenylamine 2- (α-methylpentyl) -4'-trityldiphenylamine 4,4'-bis (tertiary-butyl) diphenylamine such as:<chemistry id="chem0002" num="0002"><img file="EP0509282A2_D0002.tif" /></chemistry><chemistry id="chem0003" num="0003"><img file="EP0509282A2_D0003.tif" /></chemistry><chemistry id="chem0004" num="0004"><img file="EP0509282A2_D0004.tif" /></chemistry> The production takes place according to the methods described in BE-A 67/0500120 and CA-A 963594.

Preferred secondary aromatic amines are diphenylamine and its derivatives, which are commercially available as Naugard® (Uniroyal).

The molding compositions according to the invention contain as component C) 100 to 2000, preferably 200 to 500 and in particular 200 to 400 ppm of at least one phosphorus-containing inorganic acid or derivatives thereof, the content of component C being based on the total amount of components A) and B) in the Molding compounds.

Preferred acids are hypophosphorous acid, phosphorous acid or phosphoric acid and their salts with alkali metals, sodium and potassium being particularly preferred. Preferred mixtures are in particular hypophosphorous and phosphorous acid or their alkali metal salts in a ratio of 3: 1 to 1: 3. Organic derivatives of these acids are preferably understood to mean ester derivatives of the abovementioned acids.

As component D), the molding compositions according to the invention can contain 0 to 59.9, in particular 5 to 50 and particularly preferably 10 to 35% by weight of a fibrous or particulate filler or mixtures of such fillers.

Fibrous fillers are only glass fibers, carbon fibers, aramid fibers, potassium titanate fibers and fibrous silicates such as wollastonite.

When using glass fibers and silicate-based fillers, these can be equipped with a size and an adhesion promoter for better compatibility with the polyamide.

In general, the glass fibers used have a diameter in the range of 6-20 µm. The incorporation can take place both in the form of short glass fibers and in the form of endless strands (rovings). In the finished injection molded part, the average length of the glass fibers is preferably in the range from 0.08 to 5 mm.

Glass spheres, particulate wollastonite, quartz flour, boron nitride, kaolin, calcium carbonate, magnesium carbonate (chalk) and titanium dioxide may be mentioned here as representative fillers, of which wollastonite, titanium dioxide and kaolin are generally preferred.

As component E), the thermoplastic molding compositions according to the invention can contain 0 to 30, preferably 5 to 20% by weight, based on the sum of components A) to E), of a rubber-elastic polymer.

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

Rubbers of this type are described, for example, in Houben-Weyl, Methods of Organic Chemistry, vol. 14/1 (Thieme-Verlag, Stuttgart, 1961), pages 392 to 406 and in the monograph by CB Bucknall, "Toughened Plastic" (Applied Science Publishers , London, 1977).

Preferred types of such elastomers are the so-called ethylene-propylene (EPM) or ethylene-propylene-diene (EPDM) rubbers, which preferably have a ratio of ethylene units to propylene units in the range from 40:60 to 90:10.

The Mooney viscosities (MLI + 4/100 ° C.) of such uncrosslinked EPM or EPDM rubbers (gel contents generally below 1% by weight) are preferably in the range from 25 to 100, in particular from 35 to 90 (measured on the large rotor after 4 minutes running time at 100 ° C according to DIN 53 523).

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, 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 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.

EPM or EPDM rubbers can preferably also be grafted with reactive carboxylic acids or their derivatives. Acrylic acid, methacrylic acid and their derivatives and maleic anhydride may be mentioned here.

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, for example esters and anhydrides, and / or monomers containing epoxy groups. These dicarboxylic acid derivatives or monomers containing epoxy groups are preferably obtained by adding dicarboxylic acid or Monomers containing epoxy groups of the general formulas II or III or IV or V are incorporated into the rubber to form the monomer mixture         R₁C (COOR₂) = C (COOR₃) R₄ II<chemistry id="chem0005" num="0005"><img file="EP0509282A2_D0005.tif" /></chemistry> wherein R¹ to R⁹ represent hydrogen or alkyl groups with 1 to 6 carbon atoms and m is an integer from 0 to 20, n is an integer from 0 to 10 and p is an integer from 0 to 5.

The radicals R¹ to R⁷ are preferably hydrogen, where m is 0 or 1 and n is 1. The corresponding compounds are maleic acid, fumaric acid, maleic anhydride, allyl glycidyl ether and vinyl glycidyl ether.

Preferred compounds of the formulas II, III and V are maleic acid, maleic anhydride and epoxy group-containing esters of acrylic acid and / or methacrylic acid, glycidyl acrylate, glycidyl methacrylate and the esters with tertiary alcohols, such as t-butyl acrylate, being particularly preferred. 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 ethylene content of the copolymers is generally in the range from 50 to 98% by weight and the proportion of methacrylic acid esters is between 2 and 50% by weight. 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 methacrylic acid esters.

Copolymers of are particularly preferred <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=",">50 to 98.9</entry><entry namest="col2" nameend="col2" align="left">in particular 60 to 95% by weight of ethylene,</entry></row><row><entry namest="col1" nameend="col1" align="char" char=",">0.1 to 40,</entry><entry namest="col2" nameend="col2" align="left">in particular 0.3 to 20% by weight of glycidyl acrylate and / or glycidyl methacrylate, acrylic acid and / or maleic anhydride, and</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=",">1 up to 45,</entry><entry namest="col2" nameend="col2" align="left">in particular 10 to 35% by weight of n-butyl acrylate and / or 2-ethylhexyl acrylate.</entry></row></tbody></tgroup></table></tables>

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.

The melt index of the ethylene copolymers is generally in the range from 1 to 80 g / 10 min (measured at 190 ° C. and 2.16 kg load).

Preferred elastomers E) are emulsion polymers, the preparation of which, for example, in Houben-Weyl, Methods of Organic Chemistry, Volume XII. I (1961) and 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 and isoprene and mixtures thereof. These monomers can be copolymerized with other monomers such as, for example, styrene, acrylonitrile, vinyl ethers and other acrylates or methacrylates such as methyl methacrylate, methyl acrylate, ethyl acrylate and propyl acrylate.

The soft or rubber phase (with a glass transition temperature of below 0 ° C) of the elastomers can be 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 made 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 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, for example, epoxy, carboxyl, latent carboxyl, amino or amide groups as well as functional groups which are formed by the use of monomers of the general formula<chemistry id="chem0006" num="0006"><img file="EP0509282A2_D0006.tif" /></chemistry> can be introduced where the substituents can have the following meanings:<dl id="dl0005"><dt>R¹</dt><dd>Hydrogen or a C₁ to C₄ alkyl group,</dd><dt>R²</dt><dd>Hydrogen, a C₁ to C₈ alkyl group or an aryl group, especially phenyl,</dd><dt>R³</dt><dd>Hydrogen, a C₁ to C₁₀ alkyl, a C₆-C₁₂ aryl group or -OR⁴,</dd><dt>R⁴</dt><dd>a C₁ to C₈ alkyl or C₆ to C₁₂ aryl group which may optionally be substituted with O- or N-containing groups,</dd><dt>X</dt><dd>a chemical bond, a C₁ to C₁₀ alkylene or C₆ to C₁₂ arylene group or<chemistry id="chem0007" num="0007"><img file="EP0509282A2_D0007.tif" /></chemistry></dd><dt>Y</dt><dd>OZ- or NH-Z and</dd><dt>Z.</dt><dd>a C₁ to C₁₀ alkylene or C₆ to C₁₂ arylene group.</dd></dl>

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) ethyl acrylate .

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

So-called graft-linking monomers can also be used, ie 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), for example 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, ie the grafted-on 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, diallyl fumarate, 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 component E) is up to 5% by weight, preferably not more than 3% by weight, based on E).

Some preferred emulsion polymers are listed below. First of all, graft polymers with a core and at least one outer shell are to be mentioned, which have the following structure:<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center">Type</entry><entry namest="col2" nameend="col2" align="left">Monomers for the core</entry><entry namest="col3" nameend="col3" align="left">Monomers for the shell</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">A</entry><entry namest="col2" nameend="col2" align="left">n-butyl acrylate, ethylhexyl acrylate or mixtures thereof</entry><entry namest="col3" nameend="col3" align="left">Styrene, acrylonitrile, methyl methacrylate</entry></row><row><entry namest="col1" nameend="col1" align="left">B</entry><entry namest="col2" nameend="col2" align="left">like A but with the use of crosslinkers</entry><entry namest="col3" nameend="col3" align="left">as a</entry></row><row><entry namest="col1" nameend="col1" align="left">C.</entry><entry namest="col2" nameend="col2" align="left">like A or B</entry><entry namest="col3" nameend="col3" align="left">n-butyl acrylate, ethyl acrylate, methyl acrylate, isoprene, ethyl hexyl acrylate</entry></row><row><entry namest="col1" nameend="col1" align="left">D</entry><entry namest="col2" nameend="col2" align="left">like A or B</entry><entry namest="col3" nameend="col3" align="left">as A or C but with the use of monomers with reactive groups as described herein</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">E</entry><entry namest="col2" nameend="col2" align="left">Styrene, acrylonitrile, methyl methacrylate or mixtures thereof</entry><entry namest="col3" nameend="col3" align="left">first shell of monomers as described under A and B for the core second shell as described under A or C for the shell</entry></row></tbody></tgroup></table></tables>

Instead of graft polymers with a multi-layer structure, homogeneous, ie single-layer elastomers made from isoprene and n-butyl acrylate or their copolymers can also be 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 and an outer shell made from the copolymers mentioned above and Copolymers of ethylene with comonomers that provide reactive groups.

The elastomers E) described can also be produced by other customary processes, for example by suspension polymerization.

It is of course also possible to use mixtures of the types of rubber listed above.

Rubbers which do not contain butadiene are preferably used.

In addition to the essential components A) to C) and, if appropriate, D) and E), the molding compositions according to the invention can contain customary additives and processing aids. Their proportion is generally up to 20, preferably up to 10% by weight, based on the total weight of components A) to E).

Common additives are, for example, UV stabilizers, lubricants and mold release agents, colorants, dyes and pigments and plasticizers as well as flame retardants.

Examples of UV stabilizers are various substituted resorcinols, salicylates, benzotriazoles and benzophenones, which are generally used in amounts of up to 2.0% by weight.

Lubricants and mold release agents, which are generally added in amounts of up to 1% by weight to the thermoplastic composition, are stearic acids, stearyl alcohol, alkyl stearates and amides, and esters of pentaerythritol with long-chain fatty acids.

Flame retardants can generally be present in the molding compositions in amounts of up to 20% by weight. All flame retardant additives known for polyamide can be used, but elemental red or black phosphorus is preferred.

The molding compositions according to the invention can be produced by processes known per se by mixing the starting components in conventional mixing devices, such as screw extruders, Brabender mills or Banbury mills, and then extruding them. After the extrusion, the extrudate is cooled and crushed. The mixing temperatures are generally in the range from 260 to 350 ° C., preferably from 280 to 340 ° C.

The thermoplastic molding compositions according to the invention are distinguished from corresponding molding compositions based on aliphatic or amorphous polyamides in particular by a high stability which remains constant over long periods of time at elevated application and processing temperatures. In particular, the impact strength and light intrinsic color of these stabilized copolyamides are constant over long periods at high temperatures. In comparison to stabilized shaped bodies of aliphatic polyamides, the shaped bodies of the molding compositions according to the invention are distinguished by a significantly improved long-term effect of the stabilization.

Because of this spectrum of properties, the molding compositions according to the invention are particularly suitable for the production of moldings which are subjected to high long-term use temperatures. This applies in particular to applications in motor vehicle areas, since engine compartments require higher service temperatures of the polyamides used there due to their compact construction and increasing sound insulation measures (insulation).

Examples

Component A / 1

A partially aromatic copolyamide built up from

<dl id="dl0006"><dt>A₁) 70% by weight</dt><dd>Units derived from terephthalic acid and hexamethylenediamine and</dd><dt>A₂) 30% by weight</dt><dd>Units derived from ε-caprolactam.</dd></dl>

The viscosity number according to ISO 307 was 141 ml / g (measured in a 0.5% strength by weight solution in 96% strength sulfuric acid at 25 ° C.).

The melting point was: 298 ° C, Glass temperature: 113 ° C and Crystallinity: 26%.

Component A / 2

A partially aromatic copolyamide made up of

<dl id="dl0007"><dt>A₁) 60% by weight</dt><dd>Units derived from terephthalic acid and hexamethylenediamine and</dd><dt>A₂) 40% by weight</dt><dd>Units derived from ε-caprolactam.</dd></dl>

<tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Viscosity number according to ISO 307</entry><entry namest="col2" nameend="col2" align="right">137 ml / g</entry></row><row><entry namest="col1" nameend="col1" align="left">Melting point</entry><entry namest="col2" nameend="col2" align="right">281 ° C</entry></row><row><entry namest="col1" nameend="col1" align="left">Glass temperature</entry><entry namest="col2" nameend="col2" align="right">100 ° C</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Crystallinity</entry><entry namest="col2" nameend="col2" align="right">13 %</entry></row></tbody></tgroup></table></tables>

Component A / 3

A partially aromatic copolyamide made up of

<dl id="dl0008"><dt>A₁) 50% by weight</dt><dd>Units derived from terephthalic acid and hexamethylenediamine and</dd><dt>A₃) 50% by weight</dt><dd>Units derived from adipic acid and hexamethylenediamine.</dd></dl>

<tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Viscosity number according to ISO 307</entry><entry namest="col2" nameend="col2" align="right">142 ml / g</entry></row><row><entry namest="col1" nameend="col1" align="left">Melting point</entry><entry namest="col2" nameend="col2" align="right">292 ° C</entry></row><row><entry namest="col1" nameend="col1" align="left">Glass temperature</entry><entry namest="col2" nameend="col2" align="right">91 ° C</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Crystallinity</entry><entry namest="col2" nameend="col2" align="right">28 %</entry></row></tbody></tgroup></table></tables>

Component / V1

Polyhexamethylene adipamide

<tables id="tabl0005" num="0005"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Viscosity number according to ISO 307</entry><entry namest="col2" nameend="col2" align="right">145 ml / g</entry></row><row><entry namest="col1" nameend="col1" align="left">Melting point</entry><entry namest="col2" nameend="col2" align="right">262 ° C</entry></row><row><entry namest="col1" nameend="col1" align="left">Glass temperature</entry><entry namest="col2" nameend="col2" align="right">55 ° C</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Crystallinity</entry><entry namest="col2" nameend="col2" align="right">43 %</entry></row></tbody></tgroup></table></tables>

Component B / 1

4,4'-bis (α, α-dimethylbenzyl) diphenylamine (Naugard® 445, Uniroyal)

Component B / 2

Reaction product from diphenylamine and acetone (Naugard® A, company Uniroyal)

Component B / V1

A stabilizer based on sterically hindered phenols (Irganox® 1098, company Ciba-Geigy)<chemistry id="chem0008" num="0008"><img file="EP0509282A2_D0008.tif" /></chemistry>

Component C / 1

NaH₂PO₂ x 5 H₂O (commercial product from Merck)

Component C / 2

NaH₂PO₃ x 12 H₂O (commercial product from Merck)

Component C / 3

NaH₂PO₄ x 1 H₂O (commercial product from Merck)

Component C / V1

A mixture of copper iodide and potassium iodide in a mixing ratio of 1:10.

Component D

Glass fibers in the form of cut fibers with an average diameter of 10 µm and a length of 4.5 mm; (Gevetex® P 537 from Vetrotex)

Production of molding compounds

Components A) to C) and optionally D) were extruded on a twin-screw extruder (ZSK 30, Werner &amp; Pfleiderer) at 250 rpm and a throughput of 20 kg / h at temperatures of 320 ° C. and cooled and granulated in a water bath . The granules were dried and sprayed into test specimens at 320 ° C.

The stability was determined by heat-storing the test specimens at 140 or 160 ° C. in air and then determining the notched impact strength a_small according to DIN 53 753 (at 23 ° C, dry) depending on the storage period. From these curves, the number of days (storage period) after which the notched impact strength drops below 20 kJ / m 2 ("residual toughness") was determined as a measure of the effectiveness of the stabilizer system. In the case of glass fiber reinforced molding compounds, the impact strength was measured according to Charpy (DIN 53 453) over the period of storage until the limit of 20 kJ / m² was reached.

The compositions of the molding compositions and the results of the measurements can be found in the tables.<tables id="tabl0006" num="0006"><img file="EP0509282A2_D0009.tif" /></tables><tables id="tabl0007" num="0007"><img file="EP0509282A2_D0010.tif" /></tables><tables id="tabl0008" num="0008"><table frame="all"><title>Table 2</title><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center">example</entry><entry namest="col2" nameend="col3" align="center">Result of the measurements</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Days (T = 140 ° C) rest a_small = 20 kJ / m²</entry><entry namest="col3" nameend="col3" align="center">Days (T = 160 ° C) a_small = 20 kJ / m²</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">1</entry><entry namest="col2" nameend="col2" align="right">48</entry><entry namest="col3" nameend="col3" align="right">12</entry></row><row><entry namest="col1" nameend="col1" align="right">2</entry><entry namest="col2" nameend="col2" align="right">72</entry><entry namest="col3" nameend="col3" align="right">15</entry></row><row><entry namest="col1" nameend="col1" align="right">3</entry><entry namest="col2" nameend="col2" align="right">60</entry><entry namest="col3" nameend="col3" align="right">15</entry></row><row><entry namest="col1" nameend="col1" align="right">4</entry><entry namest="col2" nameend="col2" align="right">52</entry><entry namest="col3" nameend="col3" align="right">12</entry></row><row><entry namest="col1" nameend="col1" align="right">5</entry><entry namest="col2" nameend="col2" align="right">52</entry><entry namest="col3" nameend="col3" align="right">15</entry></row><row><entry namest="col1" nameend="col1" align="right">6</entry><entry namest="col2" nameend="col2" align="right">85</entry><entry namest="col3" nameend="col3" align="right">20</entry></row><row><entry namest="col1" nameend="col1" align="right">7</entry><entry namest="col2" nameend="col2" align="right">20</entry><entry namest="col3" nameend="col3" align="right">5</entry></row><row><entry namest="col1" nameend="col1" align="right">8</entry><entry namest="col2" nameend="col2" align="right">31</entry><entry namest="col3" nameend="col3" align="right">7</entry></row><row><entry namest="col1" nameend="col1" align="right">9</entry><entry namest="col2" nameend="col2" align="right">50</entry><entry namest="col3" nameend="col3" align="right">10</entry></row><row><entry namest="col1" nameend="col1" align="right">10^a)</entry><entry namest="col2" nameend="col2" align="right">8</entry><entry namest="col3" nameend="col3" align="right">3</entry></row><row><entry namest="col1" nameend="col1" align="right">11^a)</entry><entry namest="col2" nameend="col2" align="right">4</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">12^a)</entry><entry namest="col2" nameend="col2" align="right">4</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">13^a)</entry><entry namest="col2" nameend="col2" align="right">3</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">14^a)</entry><entry namest="col2" nameend="col2" align="right">2</entry><entry namest="col3" nameend="col3" align="right">&lt;1</entry></row><row><entry namest="col1" nameend="col1" align="right">15^a)</entry><entry namest="col2" nameend="col2" align="right">35</entry><entry namest="col3" nameend="col3" align="right">9</entry></row><row><entry namest="col1" nameend="col1" align="right">16^a)^b)</entry><entry namest="col2" nameend="col2" align="right">37</entry><entry namest="col3" nameend="col3" align="right">10</entry></row><row><entry namest="col1" nameend="col1" align="right">17^a)</entry><entry namest="col2" nameend="col2" align="right">38</entry><entry namest="col3" nameend="col3" align="right">9</entry></row><row><entry namest="col1" nameend="col1" align="right">18^a)</entry><entry namest="col2" nameend="col2" align="right">40</entry><entry namest="col3" nameend="col3" align="right">8</entry></row><row><entry namest="col1" nameend="col1" align="right">19^a)</entry><entry namest="col2" nameend="col2" align="right">3</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">20^a)</entry><entry namest="col2" nameend="col2" align="right">4</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">21^a)</entry><entry namest="col2" nameend="col2" align="right">3</entry><entry namest="col3" nameend="col3" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">22</entry><entry namest="col2" nameend="col2" align="right">70</entry><entry namest="col3" nameend="col3" align="right">18</entry></row><row><entry namest="col1" nameend="col1" align="right">23</entry><entry namest="col2" nameend="col2" align="right">63</entry><entry namest="col3" nameend="col3" align="right">16</entry></row><row><entry namest="col1" nameend="col1" align="right">24</entry><entry namest="col2" nameend="col2" align="right">59</entry><entry namest="col3" nameend="col3" align="right">12</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">25</entry><entry namest="col2" nameend="col2" align="right">39</entry><entry namest="col3" nameend="col3" align="right">25</entry></row></tbody></tgroup><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><tbody valign="top"><row><entry namest="col1" nameend="col3" align="justify">^a) for comparison</entry></row><row><entry namest="col1" nameend="col3" align="justify">^b) decomposition</entry></row></tbody></tgroup></table></tables>

The results of the measurements show that, with the amount of stabilizer remaining the same, a significantly higher long-term stability at elevated temperature is achieved in comparison with other polyamides. In addition, the measurements show that comparative stabilizers which are well suited for aliphatic polyamides do not bring about effective stabilization for partially aromatic copolyamides.