Mouldings based on Polyetheramines

The application relates to polyether amide molding compositions with excellent heat resistance and hydrolysis resistance, which are suitable for the extrusion of flexible tubes and for the production of blow-molded flexible articles.

Plasticized semi-crystalline polyamide molding compounds, in particular those based on PA11 or PA12, have long been extruded into tubes for use in automobile construction because they have excellent mechanical and chemical resistance. At the high operating temperatures under the bonnet that have been increasingly demanded in recent times, however, such molded parts stiffen after a short period of use because of the volatility of the external plasticizers used; in addition, they tend to irreversible deformation when subjected to pressure under the recently required increased operating temperatures of 110 to 150 ° C. Although these disadvantages can be avoided by using molding compositions based on higher-melting polyether ester amides, as are described, for example, in EP-A-0 095 893, this class of polyamide elastomers is not suitable for the production of useful pipes for the abovementioned uses. since the corresponding molding compositions do not by far have the resistance of classic polyamide molding compositions and also fail after only a few weeks with the hydrolysis resistance also required for this purpose.

The task was therefore to produce hydrolysis-resistant molding compositions with high heat resistance, which have a high melt viscosity and can therefore be easily extruded or blow molded. The molded parts made from it should have sufficient, permanent flexibility and, in addition, very good low-temperature impact strength without the use of external plasticizers.

This task was solved by a molding compound which contains the following components:<ul id="ul0001" list-style="none" compact="compact"><li>I. 97 to 80 parts by weight, preferably 95 to 85 parts by weight, of a polyether amide based on a linear aliphatic diamine having 6 to 14 C atoms, a linear aliphatic or aromatic dicarboxylic acid having 6 to 14 C atoms and one Polyetherdiamine with at least 3 carbon atoms per ether oxygen and primary amino groups at the chain ends,</li><li>II. 3 to 20 parts by weight, preferably 5 to 15 parts by weight and particularly preferably more than 5 to 15 parts by weight of a rubber containing functional groups, where the sum of the parts by weight of I. and II. is 100,</li><li>III. 0 to 50% by weight, preferably 0.1 to 30% by weight and particularly preferably 1 to 20% by weight, based on the molding composition, of further polymers and</li><li>IV. 0 to 10% by weight, based on the molding composition, of conventional additives.</li></ul>

In principle, polyetheramides are e.g. B. from DE-OS 30 06 961 known; However, the polyetheramides based on caprolactam or laurolactam described in more detail there are not suitable as component I, since on the one hand they have melting temperatures which are too low and on the other hand they have too low melt viscosities.

The polyetheramides to be used according to the invention as component I have a melting temperature T._m according to ISO 11357 of preferably at least 160 ° C and particularly preferably of at least 175 ° C, a relative solution viscosity η_rel preferably of at least 1.80 and particularly preferably at least 1.85, measured in a 0.5% strength by weight solution in m-cresol at 23 ° C. in accordance with ISO 307, and a resting shear viscosity at 220 ° C. preferably of at least 500 Pas and particularly preferably at least 800 Pas, measured in a mechanical spectrometer (cone plate) according to ASTM D 4440. The molding composition according to the invention produced therefrom should, if possible, be at rest-shear viscosity, measured in the same way according to ASTM D 4440, above 2000 Pas and in particular above 5000 Pas at 220 ° C., since otherwise a stable dimensionally accurate extrusion to the desired pipes or others Molded parts are not possible or only in a temperature window that is too narrow for economic production.

The incorporation of the rubber of component II leads without problems to the desired additional melt viscosity build-up if the melt or solution viscosities of the polyetheramides mentioned above are reached or exceeded.

In the production of the polyether amide, for example, 1,6-hexamethylene diamine, 1,8-octamethylene diamine, 1,9-nonamethylene diamine, 1.10-decamethylene diamine and 1.12-dodecamethylene diamine are used as diamine. The dicarboxylic acid used is, for example, adipic acid, suberic acid, azelaic acid, sebacic acid, 1.12-dodecanedioic acid, 1.14-tetradecanedioic acid, terephthalic acid or 2.6-naphthalenedicarboxylic acid. Suitable polyether diamines can be obtained by converting the corresponding polyether diols by reductive amination or coupling to acrylonitrile with subsequent hydrogenation (for example EP-A-0 434 244; EP-A-0 296 852). They usually have a number average molecular weight of 230 to 4000; their proportion in the polyether amide is preferably 5 to 50% by weight.

Commercially available polyether diamines based on propylene glycol are commercially available as JEFFAMIN® D grades from Huntsman. In principle, polyether diamines starting from 1,4-butanediol or 1,3-butanediol, or mixed polyether diamines, for example with a statistical or block-wise distribution of the units originating from the diols, are also very suitable. In general, it is desirable that the degree of difunctionality, expressed by the molar proportion of acetylatable amino and hydroxyl end groups, be at least 95% and preferably at least 98% for the polyether diamines to be used; there is a z. B. acidimetrically determinable diamine content of at least 90% and preferably at least 95% is desired. The further requirement for an approximate equivalence of the dicarboxylic acid used with the sum of diamine and polyether diamine is trivial in view of the high molar masses which must necessarily be achieved; in practice one works with amino: carboxyl molar ratios from 0.98: 1 to 1.02: 1.

In view of the desired molecular weight build-up, side reactions which damage the end groups or cleave the chains must be largely suppressed. The temperature range for the melt polycondensation is therefore limited in practice to 220 to about 245 ° C., the lower limit resulting from the melting temperatures of the underlying polyamides and the upper limit from the beginning thermal decomposition of the polyether diamines.

Surprisingly, drastic conditions must be selected for any solid-phase post-condensation to be carried out: While experience has shown that temperatures from 155 to 165 ° C. are sufficient for aliphatic polyamides such as PA612, PA1010, PA1012 or PA1212, post-condensation temperatures of 165 to 185 ° are sufficient for the polyetheramides derived therefrom C required. The solid phase post-condensation temperature should not be higher than 10 K below the crystallite melting point T to avoid caking_m lie. It is self-evident for the person skilled in the art that post-condensation is carried out either in a high vacuum or under an inert gas stream. A possible reason for the lower post-condensation activity of the polyether amides can be a lower reactivity of their partially sterically hindered amino end groups compared to conventional amino end groups derived from aliphatic diamines.

The resulting polyether amide preferably has at least 30% of the end groups, particularly preferably at least 50% of the end groups and in particular at least 60% of the end groups as amino end groups.

The rubber used according to the invention is, for example, a copolymer selected from the group<ul id="ul0002" list-style="dash" compact="compact"><li>Ethylene-α-olefin copolymers containing acid anhydride groups,</li><li>Styrene-ethylene / butylene block copolymers containing acid anhydride groups,</li><li>Ethylene-glycidyl (meth) acrylate copolymers,</li><li>Ethylene (meth) acrylic acid ester glycidyl (meth) acrylate terpolymers and / or</li><li>Ethylene- (meth) acrylic acid ester-α, β-unsaturated carboxylic anhydride terpolymers.</li></ul>

The ethylene-α-olefin copolymer containing acid anhydride groups is known in a known manner by radical reaction of an ethylene-α-olefin copolymer with an α, β-unsaturated dicarboxylic acid anhydride or a precursor thereof, such as, for. B. maleic anhydride, maleic acid monobutyl ester, maleic acid, fumaric acid, aconitic acid, itaconic acid or itaconic anhydride. The ethylene-α-olefin copolymer can be, for example, an ethylene / C₃- to C₁₂α-olefin copolymer with 20 to 96 and preferably 25 to 85 wt .-% ethylene or an ethylene / C₃- to C₁₂α-olefin / unconjugated diene terpolymer with 20 to 96 and preferably 25 to 85% by weight of ethylene and up to a maximum of about 10% by weight of an unconjugated diene such as bicyclo (2.2.1) heptadiene, hexadiene-1,4, dicyclopentadiene or 5-ethylidene norbomen. As C₃- to C₁₂α-olefin, for example, propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene or 1-dodecene are suitable. Typical examples are ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), ethylene butylene rubber, LLDPE (Linear Low Density Polyethylene) and VLDPE (Very Low Density Polyethylene). The copolymer generally contains 0.5 to 6, preferably 1 to 5 and particularly preferably 2 to 4% by weight of units which derive from the α, β-unsaturated dicarboxylic anhydride.

The styrene-ethylene / butylene block copolymers used are preferably styrene-ethylene / butylene-styrene block copolymers (SEBS) which can be obtained by hydrogenating styrene-butadiene-styrene block copolymers. However, diblock systems (SEB) or multiblock systems can also be used. Such block copolymers are state of the art. The styrene-ethylene / butylene block copolymer containing acid anhydride groups is known in a known manner by radical reaction of a styrene-ethylene / butylene block copolymer with an α, β-unsaturated dicarboxylic acid anhydride or a precursor thereof, such as, for. B. maleic anhydride, maleic acid monobutyl ester, maleic acid, fumaric acid, aconitic acid, itaconic acid or itaconic anhydride. The block copolymer generally contains 0.5 to 6, preferably 1 to 5 and particularly preferably 2 to 4% by weight of units which originate from the α, β-unsaturated dicarboxylic anhydride.

The ethylene-glycidyl (meth) acrylate copolymer usually contains essentially units of the following monomers:<ul id="ul0003" list-style="dash" compact="compact"><li>20 up to 98% by weight, preferably 30 to 97% by weight and particularly preferably 40 to 96% by weight of ethylene and</li><li>2nd up to 80% by weight, preferably 3 to 70% by weight and particularly preferably 4 to 60% by weight of glycidyl acrylate and / or glycidyl methacrylate.</li></ul>

The ethylene (meth) acrylic acid ester glycidyl (meth) acrylate terpolymer usually essentially contains units of the following monomers:<ul id="ul0004" list-style="dash" compact="compact"><li>20 up to 97.9% by weight, preferably 30 to 69.9% by weight and particularly preferably 40 to 95.9% by weight of ethylene,</li><li>0.1 to 78% by weight, preferably 1 to 67% by weight and particularly preferably 2 to 56% by weight of an acrylic acid ester and / or methacrylic acid ester with a C.₁- to C₁₂-Alcohol as well</li><li>2nd up to 80% by weight, preferably 3 to 70% by weight and particularly preferably 4 to 60% by weight of glycidyl acrylate and / or glycidyl methacrylate,</li></ul> the following compounds being used as the acrylic acid ester or methyl acrylate ester, for example: methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, dodecyl acrylate, methyl methacrylate, methyl methacrylate, methyl methacrylate, methyl methacrylate, methyl methacrylate, methyl methacrylate n-butyl methacrylate, isobutyl methacrylate and / or 2-ethylhexyl methacrylate.

The ethylene (meth) acrylic acid ester-α, β-unsaturated carboxylic anhydride terpolymer usually essentially contains units of the following monomers:<ul id="ul0005" list-style="dash" compact="compact"><li>20 up to 97.5% by weight, preferably 30 to 95% by weight and particularly preferably 40 to 92% by weight of ethylene,</li><li>2nd up to 79.5% by weight, preferably 4 to 69% by weight and particularly preferably 6 to 58% by weight of an acrylic acid ester or methacrylic acid ester and</li><li>0.5 to 6% by weight, preferably 1 to 5% by weight and particularly preferably 2 to 4% by weight of an α, β-unsaturated carboxylic anhydride,</li></ul> where as the acrylic acid ester or methacrylic acid ester and as the α, β-unsaturated carboxylic acid anhydride or its precursor, for example, the compounds mentioned above as examples can be used.

Suitable polymers of component III are primarily those which are compatible with the polyether amide, for example a polyamide. A polyamide is preferably used which is of the same type as the hard sequences of the polyether amide. The polyamide advantageously has a relative solution viscosity η_rel of at least 1.9.

Suitable additives of component IV are primarily stabilizers, carbon black, flame retardants such as. B. Melamine cyanurate, pigments and processing aids. Polymers that fall under component III are not included.

The copolymer of component II and optionally the additives of components III and IV are incorporated in the melt under shear, for example in a twin-screw extruder or a kneader.

The molding composition according to the invention can be processed, for example, by extrusion, conventional blow molding or 3D blow molding, for example by tube extrusion into an open mold half, 3D tube manipulation or 3D suction blow molding, by sequential blow molding to produce hard-soft composites or by any other blow molding process .

Furthermore, the molding compound can be processed into a multilayer composite by coextrusion, coextrusion blow molding, coextrusion 3D blow molding, coextrusion suction blow molding, etc.

In addition, the molding compound can be processed by injection molding, also with process variants such as GIT (gas pressure technology) or WIT (water injection technology).

For example, mono tubes or multilayer tubes can be produced according to the methods mentioned. These pipes can be smooth or in some areas or completely corrugated. In addition, the molding compound is used for the production of profiles of any kind, for example sealing profiles, or hollow bodies such. B. containers.

The molded parts produced according to the invention are used, for example, in motor vehicle construction, in machine and apparatus construction or in medical technology, in particular as a vacuum line, for example for brake boosters, an air guide line, a pressure hose, for example a compressed air line, a control line, a coolant line, a fuel line, a ventilation line, a windscreen washer line, a line for hydraulic clutch systems, a power steering line, a line for air conditioning systems of motor vehicles, a cable or wire sheathing, a line for the field of machine and apparatus construction or in medical technology or as an injection molded part of an oil filter or a fuel filter. These molded parts are also the subject of the invention.

The invention is explained below by way of example.

Production of the polyether amide:

A 200 1 stirred autoclave was charged with the following feed materials: <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="left">26.11 kg</entry><entry namest="col2" nameend="col2" align="left">Hexamethylenediamine as a 75% aqueous solution,</entry></row><row><entry namest="col1" nameend="col1" align="left">52.94 kg</entry><entry namest="col2" nameend="col2" align="left">1.12-dodecanedioic acid,</entry></row><row><entry namest="col1" nameend="col1" align="left">25.55 kg</entry><entry namest="col2" nameend="col2" align="left">JEFFAMIN® D400 as well</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">100 G</entry><entry namest="col2" nameend="col2" align="left">a 50% aqueous solution of hypophosphorous acid.</entry></row></tbody></tgroup></table></tables>

The starting materials were melted in a nitrogen atmosphere and heated to approx. 220 ° C. while stirring in a closed autoclave, an internal pressure of approx. 20 bar being established. This internal pressure was maintained for 2 hours; the melt was then further heated to 230 ° C. while continuously releasing the pressure to atmospheric pressure and then kept at this temperature in a stream of nitrogen for 1.5 hours. It was then evacuated to 28 mbar within 3 hours and held at this vacuum for a further 3 hours until no further increase in the melt viscosity was indicated on the basis of the torque. The melt was then discharged using a gear pump and granulated as a strand. The granules were dried under nitrogen at 80 ° C for 24 hours.

The product had the following characteristics: <tables id="tabl0002" num="0002"><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">Crystallite melting point T_m</entry><entry namest="col2" nameend="col2" align="left">193 ° C</entry></row><row><entry namest="col1" nameend="col1" align="left">Relative solution viscosity η_rel</entry><entry namest="col2" nameend="col2" align="left">1,91</entry></row><row><entry namest="col1" nameend="col1" align="left">COOH end groups</entry><entry namest="col2" nameend="col2" align="left">21 mmol / kg</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Amino end groups</entry><entry namest="col2" nameend="col2" align="left">26 mmol / kg</entry></row></tbody></tgroup></table></tables>

In this polyether amide, the ratio of the monomers used formally results in a PA612 block with an average molecular weight of 1083.

50 kg of this granulate was post-condensed for 24 hours at 175 ° C. jacket temperature under nitrogen (250 l / h) in a 250 l tumble dryer. After this time, the product had the following characteristics:<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">Crystallite melting point T_m</entry><entry namest="col2" nameend="col2" align="left">193 ° C</entry></row><row><entry namest="col1" nameend="col1" align="left">Relative solution viscosity η_rel</entry><entry namest="col2" nameend="col2" align="left">2,06</entry></row><row><entry namest="col1" nameend="col1" align="left">COOH end groups</entry><entry namest="col2" nameend="col2" align="left">14 mmol / kg</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Amino end groups</entry><entry namest="col2" nameend="col2" align="left">20 mmol / kg</entry></row></tbody></tgroup></table></tables>

Production of molding compounds:

The formulation of the molding compositions in parts by weight is shown below. The individual recipe components were incorporated in a twin-screw extruder from Werner &amp; Pfleiderer at a cylinder temperature of 250 ° C.<tables id="tabl0004" num="0004"><img file="EP1518901A2_D0001.tif" /></tables>

It can be seen that a significantly improved notched impact strength is obtained both at room temperature and at -40 ° C. if the drop in the modulus of elasticity caused by the addition of rubber is compensated for by the simultaneous addition of polyamide. The modulus of elasticity of the components can be set specifically.

The melt viscosity of the molding compositions obtained according to Examples 1 to 6 was increased compared to that of the reference molding composition, at the same time they had a higher structural viscosity (increase in the melt viscosity curve depending on the shear), which makes them particularly suitable for extrusion or blow molding applications.