DE29924506U1 - Tubing for aqueous and/or alcoholic liquids, e.g. in car windscreen washers, consists of molding material containing a polyamide and an elastic polymer with a main chain of carbon atoms only - Google Patents

Abstract

Tubing for carrying aqueous, aqueous-alcoholic or purely alcoholic liquids, in which at least the inner part of the tube wall consists of a molding material containing (I) 40-80 parts by weight (pts. wt.) polyamide and (II) 60-20 pts. wt. elastic polymer with a main chain consisting essentially of carbon atoms only. Independent claims are also included for (a) molding material as above (I + II = 100 pts. wt.) containing not more than 2 wt% extractables, as measured by extraction of the granulated material with hot 100% ethanol under reflux; (b) a process for the production of tubes by extrusion or coextrusion of this molding material.

Description

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Pipeline

The invention relates to a flexible pipe with high dimensional stability, good recovery properties and good media resistance, the interior of which consists of a material with only small extractable components. The term "pipe" can also mean "hose" here and in the following.

For many applications, for example in the automotive sector, pipes must be highly flexible. One example is pipes for windscreen washer systems, which are often made from plasticized PVC (G. Walter, Kunststoffe und Elastomere in Kraftfahrzeugen, Verlag W. Kohlhammer, Stuttgart 1985, page 187 ff.). However, over a longer period of use, this material loses plasticizer through extraction or evaporation, making it inflexible, embrittled and prone to stress cracking. In addition, this material is not sufficiently resistant to fats, oils and fuels; it also has the disadvantage that the ability of the pipes made from it to connect to the other system components is unsatisfactory.

The combination of properties required for such applications - high flexibility and kink resistance, good dimensional stability, good recovery behavior, good media resistance (particularly against fats, oils and fuels) and good bonding ability to the other system components - has so far been best achieved with polyether block amides. However, in practice it has repeatedly been found that aqueous-alcoholic medium conveyed in such pipes extracts components from the pipe material; the released components then lead to nozzle blockages or to deposits or optical defects after the washing liquid evaporates on the wetted surfaces.

The object of the present invention was therefore to provide flexible pipes as a conduit for aqueous, aqueous-alcoholic or purely alcoholic liquids made of a material which, although it has the above-mentioned advantageous properties of polyamide-based molding compounds, has a significantly

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This object is achieved by a pipeline which is selected from the group of pipelines for windscreen washer systems and pipelines for headlight washer systems and which consists, at least in the inner region of the wall, of a molding compound which essentially contains the following components:
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I. 40 to 80 parts by weight, preferably 40 to 70 parts by weight of a polyamide and

II. 60 to 20 parts by weight, preferably 60 to 30 parts by weight of an elastic polymer whose main chains consist essentially only of carbon atoms,

where the parts by weight of I. and II. add up to 100.
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In a preferred embodiment, the elastic polymer contains functional groups that enable bonding to the polyamide.

In a further preferred embodiment, the molding composition contains a maximum of 2% by weight, preferably a maximum of 1.6% by weight, particularly preferably a maximum of 1.4% by weight and very particularly preferably a maximum of 1.2% by weight of extractable components, measured according to the method described below. Corresponding molding compositions are also the subject of the present invention.

The invention will be explained in more detail below.

Polyamides in the sense of this invention are high molecular weight compounds that have -CO-NH bonds in their main chain. They are generally obtained from diamines and dicarboxylic acids or from aminocarboxylic acids by polycondensation or from lactams by polymerization. All polyamides that can be melted by heating are suitable. Examples of suitable polyamides are PA 46, PA 6, PA 66, PA 610, PA 1010, PA 612, PA 1012, PA 11, PA 12, PA 1212 and amorphous copolyamides such as PA 6,3-T. Blends of different polyamides and corresponding copolyamides can also be used. Such polyamides, blends, copolyamides and suitable production processes are state of the art.

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The elastic polymer used is produced by polymerization of compounds that have one olefinic double bond or two olefinic double bonds conjugated with each other. Elastic polymers that are produced by polycondensation, such as polyetheresteramides, polyetherester 5 or polyurethane elastomers, can, however, also be included in minor amounts, provided that the extractable portion remains in the range specified above.

The elastic polymer used according to the invention can be selected, for example, from the following classes of compounds:

a) Ethylene/C ₃ - to C ₁₂ -α-olefin copolymers with 20 to 96, preferably 25 to 85 wt.% ethylene. Examples of C ₃ - to C ₁₂ -α-olefins used are propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene or 1-dodecene. Typical examples are ethylene-propylene rubber and LLDPE.

b) Ethylene/C ₃ - to C ₁₂ -α-olefin/unconjugated diene terpolymers with 20 to 85, preferably 25 to 75% 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 in particular 5-ethylidene norbornene. The same compounds as described above under a) are suitable as C ₃ - to C ₁₂ -α-olefin. The production of these terpolymers and the copolymers described under a) using a Ziegler-Natta catalyst is state of the art.

c) Ethylene/acrylate copolymers with

- 50 to 94 wt.% ethylene,

- 6 to 50 wt.% acrylate of the formula

^R1
HX=C—COOR ²

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with R ¹ = H or C ₁ - to C ₁₂ -alkyl, for example methyl, ethyl, n-propyl,

η-Butyl, i-butyl, sec-butyl, n-pentyl, n-hexyl and

R ² = C ₁ - to C ₁₂ -alkyl, as described under R ¹ , and for example ethylhexyl, or an alkyl group carrying an epoxide group, such as

e.g. a glycidyl residue,

- 0 to 44% by weight of other comonomers, such as a C3- to C^-a-olefin as described under a), styrene, an unsaturated mono- or dicarboxylic acid, such as acrylic acid, methacrylic acid, maleic acid, maleic acid monobutyl ester or itaconic acid, an unsaturated dicarboxylic acid anhydride, such as maleic anhydride or itaconic anhydride, an unsaturated oxazoline, such as vinyloxazoline or isopropenyloxazoline, and also an unsaturated silane, such as

Vinyl trimethoxysilane, vinyl tris(2-methoxy-ethoxy)silane, 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropyltriethoxysilane.

The production of such ethylene/acrylate copolymers by radical polymerization is state of the art.

d) Styrene-ethylene/butene-styrene block copolymers (SEBS), which are obtainable by hydrogenation of styrene-butadiene-styrene block copolymers.

e) Polyalkenylenes, which can be prepared by ring-opening or ring-expanding polymerization of cycloalkenes [see KJ Ivin, T. Saegusa, "Ringopening Polymerization", Vol. 1, Elsevier Appl. Sci. Publishers, London, especially pages 121 to 183 (1984)]. Of these, polyoctenylenes are preferred (cf. A. Dräxler, Kautschuk + Gummi, Kunststoff 1981 , pages 185 to 190).

f) LPDE (high density polyethylene)

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Within the scope of the invention, mixtures of different elastic polymers can also be used, for example mixtures of one or more of the polymers described under a) to f) with polyoctenylene.

As the above shows, the elastic polymer has at least the elasticity of an LLDPE with 96 wt.% ethylene and is in this case a soft thermoplastic. In most cases, however, it has the characteristics of an elastomer.

The functional groups preferably contained in the elastic polymer can either be introduced by unsaturated monomers that are polymerized into the main chain, as described for the polymer under c), or they are introduced by unsaturated monomers that are grafted onto the polymer thermally or radically. Particularly suitable functional groups that enable bonding to the polyamide are carboxylic acid groups, acid anhydride groups, imide groups, epoxy groups, oxazoline groups or trialkoxysilane groups. Grafting unsaturated functional compounds onto polymers is state of the art; a large number of corresponding products are commercially available.

In addition to the components under I. and II., the molding compound may contain smaller amounts of additives that are required to adjust certain properties. Examples of these are pigments or fillers such as carbon black, titanium dioxide, zinc sulfide, silicates or carbonates, processing aids such as waxes, zinc stearate or calcium stearate, flame retardants such as magnesium hydroxide, aluminum hydroxide or melamine cyanurate, carbon fibers, graphite fibrils, antioxidants and UV stabilizers. In any case, care must be taken to ensure that the additives contribute as little as possible to the extractable portion.

The content of extractables is determined by extracting granules with hot 100% ethanol under reflux conditions for 8 hours.

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The pipes according to the invention are preferably formed in a single layer, i.e. they consist of the claimed molding compound over the entire cross-section. In this case, they can be produced particularly easily by extrusion. For special applications, however, it may be expedient to form them in two or more layers, with the innermost layer consisting of the claimed molding compound, with one or more layers of other materials being added to the outside, for example of other impact-resistant polyamide molding compounds, polyetheresteramide or nitrile rubber. The only important thing is that the innermost layer, which comes into contact with the medium to be transported, consists of the claimed molding compound. Multi-layer pipes are produced in a known manner by coextrusion.

Depending on the intended use, the tensile modulus of elasticity of the molding compound, which serves as a measure of flexibility, is usually in the range between 200 and 950 N/mm ² , measured according to DIN EN ISO 527/1A.

Additional flexibility can be achieved if the pipe is corrugated either in parts or completely. The production of corrugated pipes is state of the art.

The pipes according to the invention are used where aqueous, aqueous-alcoholic, purely alcoholic or comparable liquids are conveyed which have an extractive effect on polyamides or polyetheresteramides, namely as lines for windshield washer systems in motor vehicles and lines for headlight washer systems. In addition to the reduced content of extractable components, they also have the advantage of significantly improved low-temperature impact strength and high flexibility.

The invention will be explained below by way of example.

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Comparison example 1

From a molding compound of the following composition

5-99 wt.% polyetheresteramide, prepared from 76.3 parts by weight of laurolactam, 18.8 parts by weight of polytetramethylene glycol and 4.2 parts by weight of dodecanedioic acid,

- 0.5 wt.% carbon black and

- 0.5 wt.% of a stabilizer (IRGANOX® 245)

5 mm x 1 mm pipes (wall thickness 1 mm; inside diameter 5 mm) were produced by extrusion.

Both the starting granulate and the chopped pipe were then extracted in a TECATOR extractor, model Soxtec HTG, in the following way:

Approximately 2 g of granulate or tube were weighed to the nearest 0.001 g on an analytical balance and placed in an extraction thimble without loss. 50 ml of ethanol were placed in the receiver together with a boiling stone. The granulate or tube was then extracted at a thermostat flow temperature of 160 ⁰ C, initially for 7.5 hours at "boiling stage" and then for 30 minutes at "washing stage". The granulate or tube was then allowed to cool, the extraction thimble was placed in a beaker and dried for 16 hours in a vacuum drying cabinet at 130 ⁰ C. After drying, the beaker and its contents were placed in a desiccator and cooled to room temperature for approx. 3 hours.

To determine the weight loss, the extracted granulate or tube without sleeves was weighed back. Based on duplicate determinations, the weight loss was 2.4% by weight for the granulate and 2.5% by weight for the tube.

The pipes were installed in the windscreen washer system of motor vehicles; the windscreen washer tanks were then filled with an ethanol/water mixture in a ratio of 1:1, .pie.se .liquid LQs.te..diQ.extr.arjieri)aren components of the

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laid pipes; the released parts then led to nozzle blockages, especially after a longer period of downtime.

example 1
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A molding compound was produced by melt mixing the following components:

50 parts by weight of polyamide 12, _{η Γ β} γ = 1.9

50 parts by weight of EXXELOR® VA 1801 (ethylene/propylene rubber, composed of approx. 2/3 ethylene and approx. 1/3 propene, additionally functionalized with approx. 1% by weight of maleic anhydride)
0.5 parts by weight of carbon black

0.5 parts by weight of stabilizer IRGANOX® 245
15

Extraction of the granules resulted in a weight loss of 1.4%, corresponding to 1.4% by weight of extractable components.

5 mm x 1 mm pipes were produced from the molding compound by extrusion. 20

The pipes were installed in the windshield washer system of motor vehicles; the windshield washer tanks were then filled with an ethanol/water mixture in a ratio of 1:1. No nozzle blockages were found.

Example 2

A molding compound was produced by melt mixing the following components:

60 parts by weight of polyamide 12, _{η ΓΘ δ} = 1.9
40 parts by weight EXXELOR® VA 1801
0.5 parts by weight of carbon black
0.5 parts by weight

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Extraction of the granules yielded 1.2 wt.% extractables.

5 mm x 1 mm pipes were produced from the molding compound by extrusion.

The pipes were installed in the windshield washer system of motor vehicles; the windshield washer tanks were then filled with an ethanol/water mixture in a ratio of 1:1. No nozzle blockages were found.

Example 3 10

A molding compound was produced by melt mixing the following components:

64 parts by weight of polyamide 12, η _{Γβ γ} = 1.9 36 parts by weight of EXXELOR® VA 1801 0.5 parts by weight of carbon black 0.5 parts by weight of IRGANOX®

Extraction of the granules yielded 1.0 wt.% extractables. 20

5 mm x 1 mm pipes were produced from the molding compound by extrusion.

As in example 2, no nozzle blockages were detected here. Example 4:

A molding compound was produced by melt mixing the following components:

50 parts by weight of polyamide 12, η _Γθ &igr; = 1.9 50 parts by weight of KRATON® FG 1901 X (maleic anhydride-functionalized SEBS) 0.5 parts by weight of Rtiß· .··. .··. .··. .··

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0.5 parts by weight IRGANOX® 245

Extraction of the granulate yielded 1.5% by weight of extractable components. 5 mm x 1 mm pipes were produced from the molding compound by extrusion. As in Example 2, no nozzle blockages were detected here either.

Example 5:
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A molding compound was produced by melt mixing the following components:

50 parts by weight of polyamide 12, _{η Γ β} γ = 1.9

50 parts by weight of BYNEL® CXA 41 E 557 (LLPDE, according to analysis consisting of 95.2% by weight of ethene, 3.7% by weight of butene and 1.1% by weight of hexene; additionally functionalized with approx. 1% by weight of maleic anhydride)
0.5 parts by weight of carbon black
0.5 parts by weight IRGANOX® 245
20

Extraction of the granules yielded 0.8 wt.% extractable components. 5 mm x 1 mm tubes were produced from the molding compound by extrusion.

As in example 2, no nozzle blockages were detected here.

♦ · · •••••9^»· · ···

Claims (9)

1. Pipeline selected from the group consisting of pipes for windscreen washer systems and pipes for headlight washer systems, wherein the pipeline consists, at least in the inner region of the wall, of a molding compound which essentially contains the following components: A) 40 to 80 parts by weight of a polyamide and B) 60 to 20 parts by weight of an elastic polymer whose main chains consist essentially only of carbon atoms, where the parts by weight of I. and II. add up to 100. 2. Pipeline according to claim 1, characterized in that the molding compound essentially contains the following components: A) 40 to 70 parts by weight of a polyamide and B) 60 to 30 parts by weight of an elastic polymer. 3. Pipeline according to one of the preceding claims, characterized in that the elastic polymer is selected from the group - ethylene/C ₃ - to C _{12 -α} -olefin copolymers with 20 to 96 wt.% ethylene; - ethylene/C ₃ - to C _{12 -α} -olefin/unconjugated diene terpolymers with 20 to 85 wt.% ethylene and a maximum of about 10 wt.% of an unconjugated diene; - Ethylene/acrylate copolymers containing 50 to 94% by weight of ethylene, 6 to 50% by weight of an acrylate of the formula


with R ¹ = H or C ₁ - to C ₁₂ -alkyl and R ² = C ₁ - to C ₁₂ -alkyl or an alkyl group carrying an epoxy group, and 0 to 44 wt.% of other comonomers; - Styrene-ethylene/butene-styrene block copolymers (SEBS), - Polyalkenylenes and - LDPE (high density polyethylene). 4. Pipe according to one of the preceding claims, characterized in that the elastic polymer contains functional groups which enable a bond to the polyamide. 5. Pipe according to one of the preceding claims, characterized in that the polyamide is a PA 46, a PA 6, a PA 66, a PA 610, a PA 1010, a PA 612, a PA 1012, a PA 11, a PA 12, a PA 1212 and/or a PA 6,3-T. 6. Pipeline according to one of the preceding claims, characterized in that the molding compound contains a maximum of 2% by weight of ethanol-extractable components. 7. Pipeline according to one of the preceding claims, characterized in that it has a single-layer construction. 8. Pipeline according to one of claims 1 to 6, characterized in that it is constructed in two or more layers, the innermost layer consisting of the molding compound according to the claims. 9. Pipeline according to one of the preceding claims, characterized in that it is corrugated in parts or completely.