DE102019118856A1 - Ternary polymer blend, in particular for pipe extrusion, thermoplastic plastic pipe made from such a blend and its use - Google Patents

Abstract

The invention relates to a thermoplastic polyamide-polyolefin blend, in particular for the extrusion of pipes intended for fluid guidance, at least containing a polyolefin, a polyamide and a compatibilizer. In order to ensure that, while optimizing the relationship between the requirement profile and the manufacturing effort, a high level of media resistance, in particular to cooling water and aqueous zinc chloride solutions, as well as good processability of the blend by extrusion and the ability to mount a plastic pipe made from the blend on mandrels as pipe connector elements can be guaranteed , it is proposed that the polyolefin is a polypropylene-based thermoplastic elastomer, which is in a mass ratio in the range from 0.05 to 5.0 to the polyamide, the compatibilizer in a range from 7.5 to 50 parts by weight, based on 100 parts of the Mixture of the polypropylene-based thermoplastic elastomer and the polyamide, and wherein the compatibilizer contains as at least a first component a partially neutralized ionomer which is a copolymer containing ethylene and acrylic acid monomer units.

Description

The present invention relates to a thermoplastic polyamide-polyolefin blend, in particular for the production of fluid-carrying pipes by extrusion, at least containing a polyolefin, a polyamide and a compatibilizer. The invention also relates to a plastic pipe made from such a blend and its use.

Fluid-carrying line systems which, in particular in motor vehicles, have pipes as pipe sections - or, in flexible training, hoses - which are connected via pipe connectors, such as. B. mandrels, interconnectable or connected, are subject to a variety of requirements. Such line systems can in particular means for generating pressure, such. B. pumps or compressors, by means of which the fluid is conveyed through the system. This results in requirements with regard to pressure resistance. By using means for generating or dissipating heat, heating or cooling can be provided. This, as well as changing environmental conditions, results in requirements with regard to temperature resistance.

In addition to the requirements in operation, such as limited fluid, in particular water absorption, high heat resistance, pressure resistance adapted to the fluid pressure, high shear strength, etc., requirements are also placed on the line sections with regard to processability, such as B. in terms of their malleability. For example, a pipe must be able to be flared onto the mandrels of connectors. The pipe must not tear or tear, whereby - so that the pipe does not tear when it is thorned open - a certain expandability of its wall must be present. In addition, the wall of the pipe must have a certain resetting behavior - from the expanded state that occurs during the expanding process - so that, in particular without the use of further fastening means, such as. B. by hose clamps, a tight fit on the mandrel. For example, pure polyolefin pipes do not meet this requirement because they have too high a tendency to creep, which is unsuitable for mandrel connections.

The pipe must also be resistant to media. So z. B a certain zinc chloride resistance must be guaranteed, especially in cooling water applications. This is determined according to the standard SAE J 2240-2008. PA 6 and PA 66 as well as their blends with polyolefins do not meet this media resistance. Likewise, hydrolysis resistance of these materials is not sufficient at cooling water temperatures> 100 ° C.

Flame protection is also required for some applications.

Numerous technical solutions of the most varied types are known in order to meet the specified requirement profile through the parameters to be observed during operation, such as temperature and pressure, as well as through the conditions that arise during production and assembly according to the method. Pipes known from practice for cooling water applications are produced, for example, by extruding a polyamide, in particular with a wall made of PA12.

With regard to the use of material in the pipe wall, at least three options for setting an optimal balance between the requirement profile and manufacturing costs can be differentiated.

The applicant's German utility model describes the first such possibility DE 20 2011 110 917 U1 a heatable fluid line which has at least two length sections which are designed differently in terms of their material properties and / or their structural shape, namely at least on the one hand a first length section consisting of a first material containing a first polymer, and on the other hand a second length section , which consists of a second material which contains a second polymer, wherein the material of the second length section is more flexible and / or has a higher strength than the material of the first length section. The line is structured differently, ie the different length sections of the line are designed according to the locally different requirements. This technical solution has proven itself in practice. The material of the first length section can in particular contain a polymer that is an engineering plastic, while the material of the second length section can in particular contain a polymer that is a high-performance plastic.

If the terms "engineering plastic" and "high-performance plastic" are used, these terms refer to a classification of plastics with regard to their long-term service temperature that is customary in the specialist field. After that, between mass and standard plastics with a Continuous service temperature up to 90 ° C, technical plastics with a continuous service temperature up to 140 ° C and high-performance plastics with a continuous service temperature over 140 ° C are distinguished.

The continuous use temperature can be determined in various ways. In the method according to UL 746 B, a so-called temperature index is given, i.e. That is, the temperature is determined at which the polymer material still has half of its tensile strength, its tensile impact strength or its dielectric strength after 60,000 or 100,000 hours. An analogous method is the IEC 216 (International Electrical Committee), which corresponds to DIN VDE 0304. This method is used to determine the temperature at which, after 20,000 hours, the values of the mechanical and electrical properties are only half.

Based on these criteria, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polymethacrylic acid methyl ester (PMMA), acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS) are classified as bulk plastics.

Engineering plastics include polyamide (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC) and polyoxymethylene (POM).

The high-performance plastics include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polysulfones (PSU), polyaryl ether ketones (PAEK), polyphenylene sulfides (PPS) and polyimides (PI) as well as various copolymers that contain the smallest repeating chain structural units of the aforementioned compounds. Since these high-quality polymers are very complex to manufacture and consequently expensive, their use is limited to certain special cases. For this reason, despite their excellent properties, these materials are rarely or not at all used for the production of known fluid lines.

As a polymer material of the first length section according to DE 20 2011 110 917 U1 A polyamide (PA), in particular PA 6, PA 66, PA 11 or PA 12, can advantageously be selected, whereby a low-cost production of the fluid line according to the invention can be ensured with regard to the total material use. Polyamides are generally classified as engineering plastics, but they can also be given by a special design of their formulation, e.g. B. by copolymerization, the properties of high-performance plastics are given. The first length section can be designed, for example, as a plastic molded tube, with filled engineering plastics such. B. fiber-reinforced plastics can be used.

The polymer of the second length section can according to DE 20 2011 110 917 U1 advantageously an elastomer, for example hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene-propylene-diene rubber (EPDM) for temperatures up to 170 ° C, an ethylene-propylene rubber (EPM) for temperatures above 200 ° C or also be a thermoplastic elastomer (TPE). From this material class, PA 12 elastomers appear particularly suitable. These are block copolymers made from PA 12 and from polyether segments (polyether block amides PEBA). They show the essential properties of PA12, whereby the elastomeric character becomes more and more pronounced with increasing polyether content. The polymers become elastically more flexible and tougher at low temperatures.

In addition to the pipe design with sequential, section-wise material changes as a first possibility for setting a balance between the requirement profile and manufacturing effort, the utility model describes DE 20 2011 110 917 U1 also a preferred embodiment of a first length section of a fluid line with a second possibility for achieving an optimal balance between the requirement profile and manufacturing effort. In this design, the pipe wall has a two-layer structure. It comprises an outer wall, preferably made of an engineering plastic such as PA 12, and an inner wall, preferably made of a fluoropolymer such as PTFE. The inner wall can preferably be made comparatively thin in the sense of only a superficial coating of the outer wall, ie approximately with a maximum wall thickness of 300 μm, the comparatively thick outer wall ensuring the required mechanical stability. With an advantageous material-economical production method - mainly from the engineering plastic - the length section has a heat and cold resistance appropriate to the stress and, in particular due to the fluorine-containing polymer of the inner wall, an increased resistance to the fluid flowing in it, for example increased chemical resistance, especially with regard to on water absorption and / or hydrolysis.

Pipes with a multilayer wall made using polyamides are also available in, for example EP 1 717 022 B1 , EP 2 261 032 B1 , EP 2 409 830 B1 and EP 2 842 736 A1 described.

A third known possibility for setting a balance between the requirement profile and the manufacturing effort is the use of compound or preferably polyblend polymers. Compounds are plastics to which additional fillers, reinforcing materials or other additives have been added. A fiber reinforcement was already mentioned above in this regard. The compounding thus firmly bonds at least two substances with one another. The aim of compounding is to specifically modify the properties of the plastics for a specific application. For thermoplastics, compounding takes place in particular with the aid of twin-screw extruders in which the starting materials, which are usually in granular form, are melted and intimately mixed.

If two polymers are compounded, a so-called polyblend is created. Such a polyblend - also known as a polymer alloy (English: "alloy") - is a special compound, but a compound is not always a blend. Specific types of blends are mixtures of polyolefins, such as polyethylene (PE) and / or polypropylene (PP), which due to the above. Criteria under which mass plastics are to be classified, with polyamides as representatives of the higher-quality technical or even - as mentioned above - possibly the high-performance plastics.

An analysis of the known state of the art for the production of polyblends shows that the 1970s in particular were a period in which many patent applications were made in the field of PA-PE blends. A relatively comprehensive overview of this state of the art is provided by DE 42 23 864 A1 , which deals with the recycling of PA / PE waste. It is stated there that polyamide-polyolefin blends, especially polyamide-polyethylene blends, have been known to the person skilled in the art for years. These polymer alloys are distinguished by the fact that polyamide is mixed with 5 to 40% by weight of polyethylene with the aid of a process for rendering compatible, such as the use of peroxides, block copolymers or specially selected compatibilizers. These blends are characterized e.g. B. by increased impact strength and reduced water absorption. Likewise, the production of high-impact polyamides by compounding polyamide is known exclusively with modified polyolefins, especially with acid- or anhydride-functional polyethylenes. The production of such polyamide blends is z. B. described in: Kunststoffe 65 (1975), p. 139 ff, Kunststoffe 80 (1991), p 838 ff, EP 0 469 693 A2 and in the literature cited therein - e.g. B. EP 0 235 876 A2 , EP 0 245 964 A2 , EP 0 270 247 A2 , EP 0 272 695 A2 , EP 0 335 649 A2 - as in WO 8908120 A1 , JP 012 845 552 A , WO 9107467 A1 and U.S. 3,484,403 A . It is stated that (in spite of the familiarity of the various processes) a careful balancing of the individual components is necessary in each case in order to obtain optimal properties. In fact, such a property optimization with often more than one target variable represents a coordinated setting of influencing variables comprising several parameters, which the normal activity of a person skilled in the art can often exceed.

A special challenge here is that - since in a mixture of two different polymers one polymer acts as a "high molecular weight" solvent for the other - the possibilities for arranging the polymer segments are often drastically reduced, so that a highly restricted or non- The result is miscibility of the polymers. Thermodynamically this is shown e.g. B. in a non-zero enthalpy of mixing of different homopolymers. The entropy of mixing is also used as a measure.

Even saturated hydrocarbon polymers are usually not miscible with one another despite the same structural unit (-CH2-) that repeats in them and despite their chemical similarity. The mutual solubility of polyolefins also depends on the chemical structure of the polymer chain, such as the degree of branching of the chain, its length and the position of side groups.

Even in the case of copolymer pairings specially developed for the compatibilization of blend constituents - depending on the composition of the mixture and the temperature - there is also talk of miscibility doors and windows as well as immiscibility doors in the phase diagram. Often there is only a miscibility in a certain proportion of the constituents of the mixture. The percentage of different types of polymer in a blend is therefore very important.

However, the miscibility, which according to thermodynamics is understood to be complete single-phase, must be distinguished from a general compatibility of the different polymers. Polymers are compatible if the corresponding blends show the desired properties, too without having to be completely homogeneous. They can therefore also be designed in two or more phases, with one of the polymers being able to form a matrix for the other polymer and any other ingredients that may be present. A prerequisite for this, however, is the provision of a suitable compatibilizer tailored to the constituents of the mixture. However, it can also be assumed that the quantitative proportions of the constituents are highly significant.

A polyamide-polyolefin blend similar to the type mentioned is from the DE 603 02 719 T2 known. It describes flame-retardant compositions which - based on the weight, the total amount being 100 parts - contain the following components: 50 to 75 parts of the mixture of polyamide and polyolefin and 25 to 50 parts of the mixture containing: 0.1 to 48.8 parts of a flame retardant, 0.1 to 30 parts of a phosphorus-containing plasticizer, 0.1 to 10 parts of a zeolite, the total amount of these three products being between 25 and 50 parts. To make polyamide and polyolefin compatible, functionalization of the polymers through the use of copolymers is apparently intended - although not expressly emphasized. These compositions should be suitable for protecting electrical cables and optical fibers and for molding electrical housings and connectors and should therefore have an insulating effect.

A polyamide-polyolefin blend of the type mentioned is from DE 60 2004 001 610 T2 known. This describes the use of constructions with at least one layer of a mixture of polyamide and polyolefin containing nanofillers, in which the polyamide forms the matrix, and where at least one layer of another material is optionally present to achieve a barrier effect. The mixture is thermoplastic and can be used to make bottles, tanks, containers, pipes and vessels of all kinds. An ethylene-butyl acrylate-maleic anhydride copolymer and a polypropylene that was grafted with maleic anhydride and then condensed with a monoamino-PA6, as described in US Pat 5,342,886 is described.

The present invention is based on the object of creating a polyamide-polyolefin blend, in particular for the production of fluid-carrying pipes, of the generic type mentioned at the beginning, as well as a plastic pipe made therefrom, preferably usable as a cooling water pipe in an automobile, with in particular a single-layer wall The relationship between the requirement profile and the manufacturing effort should be made, preferably with the lowest possible manufacturing effort, ensuring high media resistance, in particular to cooling water and aqueous zinc chloride solutions, as well as good processability of the blend by extrusion and the ability to mount the tube on mandrels as tube connector elements. In addition, for the production of permanent mandrel connections in fluid-carrying line systems - at lower costs and high material availability - a similar expansion and creep behavior as that of PA 12 should be guaranteed.

According to the invention, this is achieved in that the polyolefin is a polypropylene-based thermoplastic elastomer which is in a mass ratio in the range from 0.06 to 4.8 to the polyamide, the compatibilizer in a range from 7.5 to 50 parts by mass based on 100 parts the mixture of the polypropylene and the polyamide and contains a partially neutralized ionomer, which is a copolymer containing ethylene and acrylic acid monomer units.

Polypropylene-based thermoplastic elastomers belong to the group of olefin-based thermoplastic elastomers (TPE-O). They combine the properties of a semi-crystalline polyolefin and an amorphous elastomer component. It can in particular be a polymer blend with a non-crosslinked phase made of the terpolymer ethylene-propylene-diene rubber (EPDM) and dispersed in a polypropylene-containing matrix. In EPDM - used on its own as a material - the saturated main chain leads to properties such as B. high weather and ozone resistance and high thermal resistance. Because of its good chemical resistance to polar media, it is used for various seals such as B. O-rings are used in contact with water / steam, cooling liquids as well as acids and alkalis. It has been shown that these properties are advantageously largely retained when it is compounded according to the invention. Commercially available EPDM rubbers have an ethylene content of 45-75% by weight. Polymers with a lower ethylene content (45-55% by weight) are amorphous and have the best low-temperature flexibility. With increasing ethylene content, the crystallinity increases (pure linear polyethylene is highly crystalline). An EPDM with a medium ethylene content (55-65% by weight) is partially crystalline. Terpolymers above 65 wt.% Ethylene have larger crystalline areas and therefore behave like thermoplastic elastomers. Even in the non-crosslinked state, these have a high tear strength.

As an alternative or in addition to EPDM, the polypropylene-based thermoplastic elastomer can also contain an ethylene-propylene copolymer (abbreviation E / P) as the second phase. This is a copolymer made from ethene and propene, and its known areas of application are, for example, hot melt adhesives and sealants.

Due to the two-phase composition of the polypropylene-based thermoplastic elastomer used as polyolefin according to the invention - together with the polyamide - the polyamide-polyolefin blend according to the invention is not just a binary but a ternary polymer alloy, i.e. a polyblend, the three constituents of which are advantageously each in their own way contribute to the desired "material made to measure".

As far as the compatibilizer is concerned, which contains, as at least one first component, a partially neutralized ionomer, which is a copolymer that contains ethylene and acrylic acid monomer units, three different types of crosslinking are known for copolymers that contain ethylene and acrylic acid monomer units: physical, ionic and covalent.

The radical copolymerization of ethylene and acrylic acid results in highly branched polymers. The carboxy groups cause very good adhesion to polar materials, while the polyethylene matrix adheres well to non-polar carrier materials. They can act to promote adhesion between the polypropylene of the TPE-O and the polyamide. Hydrogen bridges also form between the carboxy groups, which ensure good internal cohesion through physical cross-linking.

If ethylene-acrylic acid copolymers - as provided according to the invention - are then neutralized with metal ions, such as Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ or Zn ²⁺ , for crosslinking in the context of the second type of crosslinking, these groups are deposited Ion clusters together, and ionic networks are formed.

As part of the third type of crosslinking, covalently crosslinked ethylene-acrylate elastomers are obtained from ethylene-methyl acrylate-acrylic acid terpolymers, which are chemically linked with diamines.

Blends in which mixed forms of the three types of crosslinking mentioned can be present are also advantageous according to the invention.

Ionomers are obtained by copolymerization of a non-polar with a polar monomer, as in the case according to the invention from ethylene and acrylic acid monomer units (English abbreviation: EAA - Ethylene Acrylate Acid). The polar bonds push back the crystallization and lead to the aforementioned "ionic crosslinking". Compared to conventional thermoplastics, ionomers have the advantage that both secondary valence forces and ionic bonds are effective in them. These ionic bonds are particularly strong and give the fabric its characteristic properties. In addition, unlike most other plastics, they can also serve as electrolytes.

The polyblend according to the invention compounded using such a compatibilizer behaves like a thermoplastic elastomer, so that it is very suitable for pipe extrusion. This applies optimally when it is contained in the stated proportions in the range from 7.5 to 50 parts by weight based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide in the blend according to the invention.

In the context of the invention, the compatibilizer can advantageously be used as a second additional optional component, a terpolymer of ethylene, alkyl acrylate and glycidyl methacrylate, e.g. B. ethylene methacrylic glycidyl methacrylate (EnMaGma). The mass ratio of the first component of the compatibilizer to the second component of the compatibilizer can - if present - be in the range from 0.05 to 2.0, preferably in the range from 0.2 to 1.0. The crosslinking behavior achieved in this way preserves the positive properties of the ionomer, but advantageously lowers the high melting temperature occurring in the case of the ionomers mentioned, which - considered as a pure material for the ionomer - would be in the range from 290 ° C to 330 ° C, in the sense of a improved extrudability at lower processing temperatures.

As far as the polyamide as a blend component according to the invention is concerned, polyamides are an extremely large class of polymers, the individual representatives of which can be produced in different ways. The presence of functional amide groups —CO — NH— or also —CO — NR— in the macromolecule is characteristic, where R describes an organic, in particular aliphatic or also aromatic radical.

To designate the polyamides with abbreviations consisting of the letters "PA" followed by numbers and letters, the Standard DIN EN ISO 1043-1 (09/2016) referenced. According to this, polyamides which can be derived from an aminocarboxylic acid of the type H ₂ N- (CH ₂ ) _x -COOH or the corresponding lactams are identified with PA Z, where Z denotes the number of carbon atoms in the monomer (Z = x + 1) . So stands z. B. PA 6 for a polymer made from ε-caprolactam or ω-aminocaproic acid [NH- (CH ₂ ) ₅ -CO] _n , with n as the degree of polymerization. PA 11 is made from 11-aminoundecanoic acid and PA 12 from laurolactam or ω-aminodecanoic acid.

PA 11 and PA 12 are cold-resistant down to at least -50 ° C and continuously heat-resistant up to +80 ° C. By adding stabilizers and plasticizers, however, the resistance to cold and heat can be increased to values of -60 ° C or +110 ° C, briefly up to 160 ° C. The material has only a very low water absorption, with molded parts made from it showing only the slightest dimensional changes when the ambient humidity changes. Even well below the freezing point, PA 12 has extremely high impact strength and notched impact strength. Furthermore, it shows good to very good chemical resistance to grease, oils, fuels, hydraulic fluids, many solvents as well as salt solutions and other chemicals.

Polyamides that can be derived from diamines and dicarboxylic acids of the types H ₂ N- (CH ₂ ) _x -NH ₂ and HOOC- (CH ₂ ) _y -COOH are identified with PAZ1 Z2, where Z1 is the number of carbon atoms in the diamine and Z2 denotes the number of carbon atoms in the dicarboxylic acid (Z1 = x, Z2 = y + 2). So stands z. B. PA 66 for the polymer of hexamethylenediamine (HMDA, 1,6-diaminohexane) and adipic acid [NH- (CH ₂ ) ₆ -NH-CO- (CH ₂ ) ₄ -CO] _n . PA 6 10 stands for the polymer made from HMDA and sebacic acid (decanedioic acid, 1,8-octanedicarboxylic acid, HOOC- (CH ₂ ) ₈ -COOH).

Particularly suitable polyamides for the blend according to the invention are seen as mono- or dimer-chain polyamides such as PA 11, PA 12, PA 6 10, PA 6 12, PA 6 14, in which Z ≥ 11 or Z2 ≥ 10 ( at Z1 ≥ 6).

In the polyamide-polyolefin blend according to the invention, a content of additives, such as fillers, heat stabilizers, antioxidants, anti-aging agents, plasticizers or softeners, lubricants, slip agents and / or flow aids, can also preferably be provided, the additives being in a range of 0.5 to 25 parts by mass, preferably 4 to 15 parts by mass, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide, may be included.

The blend according to the invention is in a pipe, in particular in a cooling water line of an automobile, through the use of the cheaper polypropylene-based thermoplastic elastomer as a blend component with reduced material costs compared to the use of pure PA12, in particular with regard to its properties of creep resistance, media resistance and flexibility, the known PA12- Equal to or even superior to pipes.

A pipe according to the invention is characterized in that its wall is made using the thermoplastic polyamide-polyolefin blend according to the invention, in which the polyolefin is a polypropylene-based thermoplastic elastomer, which in a mass ratio in the range from 0.06 to 4.8 to the polyamide The compatibilizer is contained in a range from 7.5 to 50 parts by weight based on 100 parts of the mixture of the polypropylene and the polyamide and contains a partially neutralized ionomer which is a copolymer which contains ethylene and acrylic acid monomer units.

The pipe can advantageously be produced in particular by extrusion, but the polyblend according to the invention is also suitable for the production of other extrusion goods, such as corrugated pipes and profiles, etc.

The pipe wall can advantageously be designed in particular in one layer, but the production of a multi-layer pipe by, for example, coextrusion of one or more further layers lying radially inside and / or outside the layer consisting of the blend according to the invention is not excluded.

Further advantageous design features of the invention are contained in the dependent claims and the following description.

In relation to the following description, it is expressly emphasized that the invention is not limited to the exemplary embodiment and also not to all or several features of the combinations of features described for the exemplary embodiment. Rather, each individual partial feature of the exemplary embodiment can also have an inventive significance in isolation from all other partial features described in connection therewith, either by itself or in combination with only a few other partial features. For example, the branded products listed in Table 2 below can be replaced with alternative materials with the same or at least largely similar chemical structure with no or only marginal change in the minimum and maximum values of the percentages.

According to the procedure described below, on the one hand polyamide comparison pipes and on the other hand polyblend pipes according to the invention were produced.

The comparison pipes were made from VESTAMID® X7393. It is a standardized molding compound according to ISO 1874-PA12-HIP , EHL, 22-005, which as type PA 12-PHLY according to DIN 73 378 and DIN 74 324 is used for flexible pipes and hoses for the automotive industry. According to the above-mentioned ISO standard (including the measuring methods prescribed therein), the polymer has the properties listed in Table 1.

The polymer is supplied as a granulate and is a plasticized, highly viscous PA 12 molding compound during processing with optimized low-temperature impact strength after solidification. It is particularly suitable for the extrusion of semi-rigid pipes with high burst strength. The recommended melt temperature for profile extrusion is 220 ° C to 250 ° C. Table 1: Properties of PA12 (comparative example, VESTAMID® X7393) property value unit Physically Melt volume rate, MVR 24 cm ^3/10 min Mechanically Train module 580 MPa Yield stress 31 MPa Elongation 28 % Nominal elongation at break > 50 % Charpy impact strength, + 23 ° C 115 kJ / m ² Charpy impact strength, -30 ° C 8th kJ / m ² Thermal Melting temperature, 10 ° C / min 173 ° C Vicat softening temperature, B. 130 ° C Flammability at nominal 1.5mm HB great

The pipes according to the invention were produced on the basis of the polyblend formulation according to the invention according to the last column of Table 2, which is specified as preferred. The third and fourth columns of the table contain the minimum and maximum values of the preferred ranges. Table 2: Recipe according to the invention Trade name component Mass% minimal Mass% maximum % By mass preferred Grilamid 2S PA 6 10 10 75 65.0 Vistamaxx ™ 6202 TPE-O 5 50 10.0 Lotader® AX 8900 EnMaGma 5 20th 16.0 Aclyn® 295 EAA ionomer 1 10 3.0 Bruggolen® H333 Copper iodide 0.1 0.5 0.4 Irganox® 1098 Antioxidant I. 0.1 0.5 0.3 P-EPQ Antioxidant II 0.1 0.5 0.3 Dow-Corning® MB50-002 Polysiloxane 0.1 3 1.0 Proviplast® 024 Plasticizer 0 10 4.0 total 100

Grilamid 2S, which can be obtained from EMS-Grivory, is PA 6 10 and, as already mentioned, is produced by the polycondensation of hexamethylenediamine and sebacic acid. Hexamethylenediamine is obtained from petroleum, while sebacic acid is obtained from the organic raw material castor oil through a multi-stage chemical process. Polyamide 6 10 therefore advantageously consists of 62 percent renewable raw materials. Other special features of Grilamid 2S (PA 6 10) are its low water absorption and good dimensional stability compared to PA 6 or PA 66, its good chemical and weather resistance, its high melting point of 215 ° C and its easy processing.

Vistamaxx ™ 6202 is offered as granules by ExxonMobil and is a polypropylene-based thermoplastic elastomer with isotactic propylene repeating units and a random distribution of ethylene groups in the polyolefin copolymer. The ethylene content is 15 to 16% by mass.

In this context, it should be noted that within the scope of the invention - notwithstanding the above. customary compositions - in the polypropylene-based thermoplastic elastomer an ethylene content of less than 40% by mass is considered optimal, in particular an ethylene content in the range of only 7% by mass to 25% by mass, preferably in the range of 12% by mass. % to 19 mass%. Accordingly, the propylene content is higher than that of the known polypropylene-based thermoplastic elastomers described above.

Another special feature of Vistamaxx ™ 6202 is that it does not use the classic Ziegler-Natta catalysts, which have the disadvantage that they usually have to be used as heterogeneous catalysts on a carrier material because they are not soluble in organic solvents but is made with metallocene catalysts. Metallocenes are a group of organometallic compounds in which a central metal atom is sandwiched between two cyclopentadienyl ligands (C ₅ H ₅ , abbreviation: Cp). The metallocene catalyst enables the isotactic arrangement of the propylene repeat units, control of the molecular weight distribution and the degree of linearity or branching of the molecules - and thus later crosslinking. As a result, in the polyblend according to the invention, the viscoelastic properties can advantageously be influenced in the sense of a reduced tendency to creep.

According to the manufacturer's specification, Vistamaxx ™ 6202 has the properties listed in Table 3. Table 3: Properties of Vistamaxx ™ 6202 property value unit Determination method Physically density 0.86 g / cm ³ ASTM D1505 Melt index MFR 190 ° C / 2.16 kg 9.1 g / 10 min ASTM D1238 Mechanically Tensile strength (break) > 5.5 MPa ASTM D638 Elongation (break) > 800 % ASTM D638 Shore hardness (A) 64 - ASTM D2240 Tear resistance (form C) 32.0 kN / m ASTM D624 Thermal Vicat softening temperature 45.2 ° C ExxonMobil method

For the determination methods, the respective versions of the standard that were valid on 01/01/2017 are to be used.

Table 4 below contains typical properties of Lotader® AX 8900. Table 4: Properties of Lotader® AX 8900 property value unit Determination method Physically density 0.94 g / cm3 ISO 1183 ASTM D1505 Melt index MFR 190 ° C / 2.16 kg 6th g / 10 min ISO 1133 ASTM D1238 Melting point 65 ° C ISO 11357-3 Mechanically Tensile strength (break) 4th MPa ISO 527-2 ASTM D638 Elongation (break) 1100 % ISO 527-2 ASTM D638 Shore hardness (A / D) (measuring time 1 s) 64/18 - ISO 868 ASTM D2240 Thermal Vicat softening temperature <40 ° C ISO 306 ASTM 1525

Lotader® AX 8900 is a terpolymer with a statistical distribution of its repeat units: ethylene (68% by mass), acrylic ester (24% by mass) and glycidyl methacrylate (8% by mass). It is produced in high pressure autoclaves and sold by Arkema.

For the methods of determining the properties listed in Table 4, the respective versions of the standards that were valid in February 2018 are to be used. Table 4 also shows that European ISO standards lead to the same measurement results as the US ASTM standards.

The acrylic ester components of Lotader® AX 8900 (EnMaGma) bring about partial molecular polarity in the blend according to the invention, reduce hardness and improve thermal stability during processing. As the acrylic ester content increases, the flexibility of the end product and its impact strength increases due to the associated decrease in crystallinity. The glycidyl methacrylate causes a reactivity towards OH, COOH and NH ₂ groups, whereby an optimally homogeneous distribution is achieved during the mixing process in the melt with the polymers for which it is used as a compatibilizer. Lotader® AX 8900 is not only compatible with LDPE, but advantageously also with ethylene-containing copolymers, such as the ethylene-containing TPE-O described above.

Aclyn® 295 is an ionomer from Honeywell, usually used in inks and coatings, which contains ethylene and acrylic acid monomer units and the chemical formula (-CH ₂ -CH ₂ -COO-CH ₂ -CH ₂ -) _x Zn _y Has. It is 98 percent neutralized with zinc (y = 0.98x), and therefore essentially to be regarded as a salt. The use of Aclyn® 295 in the polyblend according to the invention has a positive effect on a high level of corrosion resistance, in particular to zinc chloride solutions.

Bruggolen® H333 is a heat stabilizing additive from the Brüggemann group of companies. The heat stabilizers sold under the brand name Bruggolen® serve to prevent the phenomenon that occurs with many polymer materials, where the influence of heat, light and atmospheric oxygen can in some cases significantly change the physical properties and appearance of the respective plastic. A distinction is made between processing stabilizers, which primarily counteract polymer degradation in the melt phase - i.e. during compounding, injection molding or extrusion, Long-term stabilizers that prevent polymer degradation during use of the precast element at elevated ambient temperatures (60 ° - 130 ° C), high-temperature stabilizers that are effective up to 180 ° C, and UV stabilizers to effectively protect the precast elements against polymer degradation caused by UV radiation. Combinations of various heat-stabilizing additives can result in additional synergy effects. Specifically, the Bruggolens® H333 additive used is the active ingredient copper iodide, which stabilizes polyamides at temperatures of up to 180 ° C.

Irganox® 1098 is the trade name for benzene propanamide, N, N'-1,6-hexanediylbis [3,5-bis (1,1-dimethylethyl) -4-hydroxy. It is a sterically hindered phenolic compound. It is a so-called primary antioxidant (“Antioxidant I”) and is produced by the company BASF in order to achieve increased thermal stability in polymers, especially polyamides, whereby its addition can in particular avoid discoloration of the polymer.

P-EPQ, which - as can be seen from Table 2 - can be used in a formulation according to the invention as a so-called secondary, phosphorus-based antioxidant (“Antioxidant II”), prevents thermo-oxidative decomposition and yellowing during processing. It is a multi-component system with the CAS number 119345-01-6. This Chemical Abstracts Service number also contains the exact chemical structure, the product names of various other suppliers and its properties.

The polysiloxane product Dow-Corning® MB50-002 from Dow-Corning Corporation is listed as a further additive in Table 2. These are pellets in which an ultra-high molecular weight (UHMW) polysiloxane is finely dispersed at 50% by mass in a low-density polyethylene matrix (LDPE). Ultra high molecular weight (UHMW) means that the mean molecular weight of the siloxane is above 300,000 g / mol and that the polysiloxane has a kinematic viscosity of above 5,000,000 mm ² s ^-1 - determined according to DIN 51562 (01/1999) at 40 ° C. In the blend according to the invention, it improves the flowability and reduces the wall adhesion when the polymer mass is shaped. Due to its chemical similarity to Vistamaxx ™ 6202 (presence of CH ₂ groups), the LDPE has a high level of compatibility with the polypropylene-based thermoplastic elastomer of the formulation, especially when it acts as a compatibilizer.

Table 2 lists Proviplast® 024 from Proviron as the last ingredient in the formulation. It is a plasticizer that can be used equally well as plasticizers for PA 6 10, PA 6 12, PA 10 10, PA 11 and PA 12. Proviplast® 024 is by its chemical nature a sulphonamide, namely N-butylbenzenesulphonamide.

It can be seen from Table 2 that the polypropylene-based thermoplastic elastomer in the preferred blend composition is in a mass ratio of 0.154 (10/65) to the polyamide. It is therefore in a preferred range from 0.1 to 3.0. According to the invention, this mass ratio should be at least in the range from 0.05 to 5.0.

The compatibility factor (sum of first component and second component 16 + 3 = 19) is - based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide (65 + 10 = 75) - to 25.3 parts (19/75) included in the mix. It is therefore in a preferred range of 12 to 30 parts by weight, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide. According to the invention, the compatibilizer should be present in at least a range from 12 to 30 parts by weight, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide.

The mass ratio of the ionomer as the first component of the compatibilizer to the terpolymer of ethylene, alkyl acrylate and glycidyl methacrylate as the second component of the compatibilizer is 0.187 (3/16). It is therefore in a preferred range from 0.2 to 1.0. The total of the additives is 6 mass%. Based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide (65 + 10 = 75) this is 8 parts by weight. The proportion is therefore in a preferred range of 4 to 15 parts by weight, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide. According to the invention, the mass ratio should be at least in the range from 0.05 to 2.0.

The compound was produced in a twin screw extruder with a screw diameter of 25 mm. The constituents introduced in the solid state were thereby melted and treated at a temperature in the cylinder of 250 ° C until a homogeneous melt is established.

The pipes were produced in an extruder with a screw diameter of 45 mm. A barrier screw with a ratio of length L to diameter D of 25 was used. It is characteristic of a barrier screw that an additionally inserted web, the so-called barrier web, separates the solid from the melt in the plasticizing zone. The freshly melted material can flow out of the solids channel via the barrier web into the melt channel, while the barrier gap width is dimensioned so that the solid is retained. This ensures a well-digested melt and prevents unmelted solid particles from escaping from the plasticizing zone. The temperatures in the extruder were as follows: feed zone - 240 ° C, compression zone - 245 ° C, discharge zone - 250 ° C, extrusion head - 250 ° C. The geometry of the comparison tubes and the tubes according to the invention could equally be described by the specification 4.05 × 1 mm.

Tables 5 and 6 contain representations of the tensile tests on the pipes using the ZWICK ROELL Z020 after Standard DIN EN ISO 527-2: 2012-06 obtained test results, Table 5 relating to the values before heat aging and Table 6 to the values afterwards. Table 5: Mechanical pipe properties parameter unit comparison invention Tensile module MPa 580 586 Breaking force Fmax N 509 338 Elongation at break % 338 169 Weight G 2.03 1.45 Table 6: Mechanical pipe properties after heat aging for 72 h at 130 ° C and percentage change compared to the unaged pipe parameter unit comparison invention Breaking force Fmax N 538 376 Change of Fmax % 5.7 11.2% Elongation at break % 270 118 Change in elongation at break % -20.1 -30.2 Weight G 1.91 1.39 Weight loss % -6.1% -3.9%

With approximately the same tensile modulus, the tube according to the invention contains fewer volatile components than the comparison tube, as is evident from the weight loss during heat aging, which indicates that the low tensile modulus in the comparison material is achieved via plasticizers. Overall, due to the increase in tensile strength and the decrease in the elongation at break after heat aging, the pipe according to the invention has a high level of suitability for use as a cooling water pipe in an automobile in terms of mechanical properties.

In addition, there is a high level of media resistance, in particular to cooling water and aqueous zinc chloride solutions. The blend according to the invention has good processability by extrusion, with the ability to mount pipes according to the invention on mandrels as pipe connector elements is ensured. The production of permanent mandrel connections in fluid-carrying pipe systems shows - with lower costs and high material availability - a similar expansion and creep behavior as that of PA 12.

In the polymer blend according to the invention there is advantageously an optimal combination of the material properties of long-chain polyamides as engineering plastics, in particular with creep resistance, media resistance and flexibility similar to PA 12, with high media resistance and low-cost (inexpensive) production as well as the easy availability of polyolefins as bulk plastics .

The person skilled in the art can also supplement the invention with further expedient technical embodiments without departing from the scope of the invention. So z. B. the known methods for optimizing the ratio of requirement profile to manufacturing costs by material variation in sequentially successive sections of the pipeline or in the radial direction in the pipe wall successive layers are used combinatorially.

Thermoplastic pipes according to the invention have in particular an excellent ability for crack-free and creep-free assembly on a mandrel as a pipe connector element as well as optimally high media resistance, in particular - under the aspect of use as cooling water pipes - high hydrolysis resistance and zinc chloride resistance according to SAE J 2240. They are therefore particularly suitable for use as cooling water pipes in an automobile.

Furthermore, the invention has not yet been restricted to the combinations of features defined in the independent claims, but can also be defined by any other combination of specific features of all of the individual features disclosed. This means that in principle practically every individual feature of the independent claims can be omitted or replaced by at least one individual feature disclosed elsewhere in the application.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 202011110917 U1 [0008, 0014, 0015, 0016]
• EP 1717022 B1 [0017]
• EP 2261032 B1 [0017]
• EP 2409830 B1 [0017]
• EP 2842736 A1 [0017]
• DE 4223864 A1 [0020]
• EP 0469693 A2 [0020]
• EP 0235876 A2 [0020]
• EP 0245964 A2 [0020]
• EP 0270247 A2 [0020]
• EP 0272695 A2 [0020]
• EP 0335649 A2 [0020]
• WO 8908120 A1 [0020]
• JP 012845552 A [0020]
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• US 3484403 A [0020]
• DE 60302719 T2 [0025]
• DE 602004001610 T2 [0026]
• US 5342886 [0026]

Non-patent literature cited

• Standard DIN EN ISO 1043-1 (09/2016) [0041]
• ISO 1874-PA12-HIP [0053]
• DIN 73 378 [0053]
• DIN 74 324 [0053]
• ISO 527-2 [0062]
• ISO 306 [0062]
• Standard DIN EN ISO 527-2: 2012-06 [0077]

Claims (15)

Thermoplastic polyamide-polyolefin blend, in particular for the extrusion of pipes intended for fluid guidance, at least containing a polyolefin, a polyamide and a compatibilizer, characterized in that the polyolefin is a polypropylene-based thermoplastic elastomer, which in a mass ratio in the range from 0.05 to 5.0 to the polyamide, the compatibilizer being contained in a range from 7.5 to 50 parts by weight, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide, and the compatibilizer being a partial as at least one first component contains neutralized ionomer, which is a copolymer containing ethylene and acrylic acid monomer units. Polyamide-polyolefin blend according to Claim 1 , characterized in that the polypropylene-based thermoplastic elastomer is in a mass ratio in the range from 0.1 to 3.0 to the polyamide. Polyamide-polyolefin blend according to Claim 1 or 2 , characterized in that the compatibilizer is contained in a range of 12 to 30 parts by weight, based on 100 parts of the mixture of the polypropylene-based thermoplastic elastomer and the polyamide. Polyamide-polyolefin blend according to one of the Claims 1 to 3 , characterized in that the polypropylene-based thermoplastic elastomer is a polymer blend with a phase of ethylene-propylene-diene rubber and / or ethylene-propylene copolymer dispersed, in particular uncrosslinked, in a polypropylene-containing matrix. Polyamide-polyolefin blend according to one of the Claims 1 to 4th , characterized in that the polypropylene-based thermoplastic elastomer has an ethylene content of less than 40% by mass, in particular an ethylene content in the range from 7% by mass to 25% by mass, preferably in the range from 12% by mass to 19% by mass Mass%. Polyamide-polyolefin blend according to one of the Claims 1 to 5 , characterized in that the polypropylene-based thermoplastic elastomer is made with metallocene catalysts. Polyamide-polyolefin blend according to one of the Claims 1 to 6th , characterized in that the partially neutralized ionomer of the first component of the compatibilizer 80 percent to 99 percent, preferably 92 percent to 98 percent, with metal ions, such as Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ or in particular Zn ^{2 +} , is partially neutralized. Polyamide-polyolefin blend according to one of the Claims 1 to 7th , characterized in that the compatibilizer contains a terpolymer of ethylene, alkyl acrylate and glycidyl methacrylate as the second component. Polyamide-polyolefin blend according to one of the Claims 1 to 8th , characterized in that a mass ratio of the first component of the compatibilizer to a / the second component of the compatibilizer is in the range from 0.05 to 2.0, preferably in the range from 0.2 to 1.0. Polyamide-polyolefin blend according to one of the Claims 1 to 9 , characterized in that the polyamide is described according to DIN EN ISO 1043-1 as PA Z or PA Z1 Z2, where Z ≥ 11 or Z1 ≥ 6 and Z2 ≥ 10. Polyamide-polyolefin blend according to one of the Claims 1 to 10 , characterized by a content of additives such as fillers, heat stabilizers, aging inhibitors, antioxidants, plasticizers and / or flow aids, the additives in a range of 0.5 to 25 parts by weight, preferably 4 to 15 parts by weight, based on 100 parts of the mixture the polypropylene-based thermoplastic elastomer and the polyamide. Thermoplastic plastic pipe whose pipe wall is at least partially made of a polyamide-polyolefin blend according to one of the Claims 1 to 11 consists. Plastic pipe after Claim 12 , characterized in that the pipe wall is formed in one layer and completely made of a polyamide-polyolefin blend according to one of the Claims 1 to 11 consists. Connection comprising a thermoplastic plastic pipe according to Claim 12 or 13 and a mandrel as a pipe connector element. Use of a thermoplastic plastic pipe according to Claim 12 or 13 as a cooling water pipe in an automobile.