DE3439312A1 - Plastic hose - Google Patents

Abstract

A plastic hose with a double-layer structure is described, which comprises as inner layer a mixed polyamide/rubber compound with a phase structure in which the polyamide is present as matrix phase and the rubber as disperse phase and is obtained by mixing the polyamide with the rubber in the presence of a vulcanisation agent and, as outer layer, a resin-like material of the polyolefin series which, via functional groups contained therein, is firmly bonded to the polyamide/rubber compound. The hose according to the invention can be easily produced by mixing the polyamide with the rubber for 3 to 30 minutes in the presence of the vulcanisation agent at a temperature above the melting point of the polyamide and coextruding it in the molten state with the resin-like material of the polyolefin series containing functional groups. The hose according to the invention is suitable in particular as a line for cooling media, such as fluorinated hydrocarbons (Freon) for use in motor vehicle radiators and air-conditioning systems.

Description

The invention relates to a flexible plastic hose,

which is particularly useful as a conduit for fluorinated hydrocarbons (Freon) is suitable. The plastic hose according to the invention comprises a polyamide-rubber mixture as an inner layer over which a polyolefin material with functional groups as outer layer is placed.

In general, pipes for fluid materials are of two types known from hoses. One type of hose that has been known for a long time consists of one plastic-coated, tubular textile jacket. This type of hose, e.g. in the form of fire hoses, is used as a conduit for water, gas and aqueous slurries widespread.

This type of tubing is tough and suitable for a wide variety of uses outdoors, where they are exposed to severe environmental stress. These hoses but also have some serious drawbacks. One of these drawbacks is there in that they are not fully flexible, especially if their diameter is only is about 2.5 cm (1 in).

They tend to form creases or wrinkles when they are in compliance be bent or curved with the surface of intricately shaped structures. Another disadvantage of these hoses is that they, especially when Use under increased pressure, not as lines for various organic Liquids can be used as the rubbery coating material these hoses are affected by the organic liquid due to peeling or swelling can be. The other known type of hose is essentially around a plastic hose, which may be provided with a protective coating is. Hoses of this type are more flexible, especially with smaller diameters. With the appropriate choice of resin material for such hoses, it is possible to various fluid materials through these hoses che to conduct.

With the latter hose types, we know that a certain Improvement in gas permeability and resistance to ozone, oil and Warmth as well as a weight saving can be achieved using polyamide as the resin material used for the hose. Compared with conventional rubber-like tubing elastic materials, however, polyamide tubes are so rigid that they are difficult to use can be bent or curved. They are even prone to cracking or formation Breaks when forcefully bent. To overcome this disadvantage, is disclosed in Japanese Utility Model Application Laid-Open No. 52-163220 Polyamide tubing subjected to a wave treatment to improve its flexibility. However, a polyamide tube with such a corrugated structure shows a reduced one Compressive strength. Furthermore, to improve the flexibility of a polyamide hose proposed to use a double-layer hose, in which the rigid polyamide hose is provided as an inner layer over which an elastic tube is placed.

The thickness of the polyamide tube should be less than 0.5 mm. According to this proposal, there is still the disadvantage that the inner polyamide tube tends to crack or peel off. Because polyamide has a tendency to absorption shows moisture, water is accumulated inside polyamide tubes, which can have harmful effects with the intended use. Around to avoid this disadvantage, according to the laid-open Japanese utility model 56-120 # 82 suggested a layer to prevent water ingress.

Chlorosulfonated polyethylene is used as such a layer Preventing water from penetrating between a first reinforcement layer and laid a second reinforcement layer. If this method is used on polyamide tubing an additional process step for vulcanizing the chlorosulfonated Polyethylene required, which makes the production of such hoses difficult.

Also from Japanese Utility Model Laid-Open 58-94975 known rubber hoses, which consist of a thin inner metal-plastic composite layer and a rubber layer having a reinforcing fiber layer contained therein exist. Such plastic hoses are said to be flexible in terms of their flexibility and the impermeability to fluorinated hydrocarbons and moisture prove to be excellent. However, these rubber hoses still have the Disadvantage that it is difficult to achieve complete adhesion between the composite layer and the rubber layer.

Recently it was found that the from the water absorbency The disadvantages resulting from polyamide can be overcome by removing the polyamide with a resin-like material of the polyolefin series with functional groups, the has good impermeability to water, is coextruded and has a strong bond of the resinous material on the outer surface of the polyamide tube. On the other hand, it was also found that by providing a polyamide with good flexibility to overcome the out of the rigid nature of this Material resulting disadvantages by mixing the polyamide with a plasticizer or rubber or by copolymerization of the polyamide with a rubber, the Adhesion of the polyamide to the resinous polyolefin series material with a content in functional groups is considerably worsened.

The object of the invention is to overcome the aforementioned disadvantages of polyamide tubing overcome and plastic tubing with improved flexibility and water impermeability provide. According to the invention, plastic hoses should thus be made by coextrusion a mixed polyamide rubber composition as an inner layer and a resinous one Materials of the polyolefin series with a content of functional groups as the outer Layer can be made. These plastic tubes should also be impermeable for fluo- be rated hydrocarbons and thus act as lines suitable for cooling media.

In order to overcome the above-mentioned disadvantages, numerous studies have been made carried out on plastic hoses, in particular on polyamide hoses. Included it was surprisingly found that when rubber is vulcanized in dispersed state in a polyamide and with subsequent coextrusion of the mixed Polyamide rubber compound as an inner layer with a resinous material of the Polyolefin series with a content of functional groups as the outer layer Plastic hose is obtained in which all the aforementioned disadvantages of conventional Plastic hoses are completely removed.

The invention therefore relates to a plastic hose with a double layer Structure, the inner layer of which is a polyamide-rubber mixture with a phase structure, in which the polyamide is the matrix phase and the rubber is the disperse phase, this mixture by mixing the polyamide with the rubber in the presence of a vulcanizing agent, and a resinous one as the outer layer Material of the polyolefin series, which is fixed via the functional groups it contains is bound to the polyamide-rubber mixture.

The plastic tube according to the invention is made by coextrusion of the the aforementioned mixed polyamide-rubber composition with a phase structure in which the polyamide is present as a matrix phase and the rubber as a disperse phase a resinous polyolefin series material containing functional Groups that have good water impermeability and adhesiveness to polyamides, manufactured.

The invention is explained in more detail below with reference to the drawing. They show: FIG. 1 a perspective view of a basic configuration leadership style a plastic tube of the invention; and FIG. 2 is a perspective view of a An embodiment of the plastic tube which is particularly suitable in practice Invention.

In Fig. 1 there is an inner layer 1 made of the polyamide-rubber compound provided with the aforementioned phase structure, over which an outer layer 2, which is made from the resinous polyolefin series material that is about in it functional groups contained is bound to the inner layer. There the inner layer 1 has a structure such that the vulcanized rubber phase is dispersed in the polyamide matrix phase, the inner layer 1 turns out to be Greatly improved in terms of flexibility and proves to be broad overall impermeable to freon. On the other hand is the outer layer 2, which differs from the resinous Material of the polyolefin series with functional groups is derived from the outer Surface of the inner layer 1 provided by coextrusion, the resin-like Material containing groups partially or entirely at the interface between the both layers 1 and 2 with the polyamide to form an integrally connected Hose have been implemented. The outer layer 2 can therefore only be removed with difficulty peel off from the inner layer 1 and gives the inner layer 1 good water impermeability. The term "coextrusion" means simultaneous extrusion of the polyamide-rubber mixture in a molten state and the polyolefin series resinous material in a molten state State with the formation of a double-layer hose from the mixed melt to understand.

The coextrusion process itself is carried out in a conventional manner, for example using a twin extruder. Regarding the thickness of the There are no special restrictions on the inner or outer layer. In general the thickness of the inner or outer layer depending on the type and pressure of the fluid medium to be conducted through the hose and depending on the intended use chosen, these thicknesses i: n general in the range of 0.2 to 5 mm and preferably from 0.5 to 2 mm. Exist in a corresponding manner no special restrictions on the hose diameter, since the diameter depending on various factors, e.g. resistance to internal pressure, Type of fluid media to be passed through, length of the hose, flexibility as well The size of the connectors to which the hoses are connected vary can. In general, the diameter is 5 to 30 mm and preferably 10 to 20 mm.

The embodiment shown in FIG. 2, which is particularly suitable for practice of the hose according to the invention has an inner layer 1, which is connected to the outer Layer 3 is covered. There is a reinforcement layer 4 and a outer layer or protective layer 5. Layers 4 and 5 generally serve the reinforcement and protection of the hose against external damage. in the Generally, a woven or non-woven textile material is used as the reinforcing layer 4 and a scratch-resistant, abrasion-resistant resin material is used as the protective layer 5. If necessary, these layers 4 and 5 can be further reinforced by incorporated metal threads, wires or other reinforcing components into them. Included it should be noted that the reinforcement layer 4 and the protective layer 5 for the inventive hose represent contingency components, of which as required either or both can be used. The layers 4 and / or 5 can be integral with With the help of a suitable binding agent, it can be connected to the hose.

The one for the mixed polyamide-rubber mass that makes up the inner layer 1 represents, the polyamide used is among the commercially available polyamide materials selected. Corresponding examples are nylon 6, nylon 6-6, nylon 11, nylon 12, nylon 6-9, nylon 6-10, nylon 8 or mixtures or copolymers of these polyamides, such as nylon 6 / 6-6 or nylon 6 / 6-10. Using nylon 6 or 6-6 provides one relative soft blend, while nylon 11 gives a blend with moderate flexibility. In view of the flexibility and use of a desired Commercially available material nylon 6, nylon 6-6 or nylon 11 are preferably used.

The rubber to be mixed with the polyamide in the inner layer 1 is made from a large number of natural and synthetic rubbers selected. Specific examples are natural rubber (NR) and isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), isobutylene-isoprene rubber (IIR), chloroprene rubber (CR), ethylene propylene rubber (EPM, EPDM), chlorosulfonated Polyethylene (CSM), chlorinated polyethylene (CPE), acrylic rubber (ACM), epichlorohydrin rubber (EO, ECO), urethane rubber (U), silicone rubber (Q), fluororubber (FKM) and Butadiene rubber (BR). Furthermore, chemically modified derivatives of the aforementioned Types of rubber and mixtures of these types of rubber are used, e.g. with carboxyl or epoxy group-modified rubbers and mixtures of NBR and ECHO. Under these types of rubber are acrylonitrile butadiene rubber, epichlorohydrin rubber, acid-modified (e.g. containing carboxyl groups) ethylene-propylene rubber and mixtures of acrylonitrile butadiene rubber and epichlorohydrin rubber are preferred, as they are well compatible with the polyamide and tubing with more satisfactory Result in strength. The use of a mixture of acrylonitrile butadiene rubber and epichlorohydrin rubber is particularly preferred as it is a hose with excellent Resistance to Czon and to whitening under stress results.

In the inner phase, the polyamide and the rubber are in proportions from 30 to 70 percent by weight of polyamide to 70 to 30 percent by weight of rubber is used.

If the polyamide content exceeds 70 percent by weight, the Desired improvement in the flexibility of the Hardly any more hose determine. On the other hand, if the proportion of polyamide is below 30 percent by weight, then the thermcplastischen properties of the mass are impaired, so that the Machinability suffers significantly. A polyamide content of 4C to 60 percent by weight and a rubber content of 60 to 40 percent by weight are used for the inventive Hose particularly preferred.

The rubber is dispersed in the polyamide rubber mixture Condition in the polyamide medium with the help of a vulcanizing agent (or crosslinking agent) vulcanized (or crosslinked). You can find more information about special vulcanizing agents not be done as this will vary greatly depending on the type of rubber used varies. In general, those vulcanizing agents which undergo vulcanization are preferred (Crosslinking) of the rubber used at the kneading temperature (mixing temperature) accomplish within 3 to 30 minutes. In general, a temperature selected as kneading temperature above the melting point of the polyamide. Is the rate of vulcanization of the rubber too quickly, so it becomes difficult to distinguish the rubber as a disperse phase to disperse in the polyamide matrix phase.

Examples of vulcanizing agents (crosslinking agents) included among such Conditions effective are m-phenylene bis-maleimide or a mixture of m-phenylene bis-maleimide and dibenzothiazyl disulfide for unsaturated rubbers such as SBR and NER, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne-3 for types of rubber that are capable of forming peroxy bridges, such as EPM, EPDM and BR, as well as alkylphenol-formaldehyde resins (reactive types) or similar phenolic resins for SBR, NBR, CR, IIR and types of rubber with a content of carboxyl groups. These Vulcanizing agents are commercially available and are used in such amounts those generally required for the vulcanization of the rubber used are. By kneading the rubber with the polyamide in the presence of the vulcanizing agent at temperatures above the melting point of the Pclyamide used, the desired mixed polyamide rubber Mass with a phase structure, at that the rubber is present as a disperse phase and the polyamide is present as a matrix phase, obtain.

The one used for coextrusion with the polyamide-rubber mixture Resin-like material of the polyolefin series contains functional groups that react with the polyamide are capable. The resinous material is derived from polymers or copolymers of at least one lower olefin, such as ethylene or propylene and butylene, the total amount of ethylene, propylene and or butylene being 50 percent by weight or more and functional groups such as carboxyl groups, epoxy groups and Amino groups contained in the molecular chain of the polyolefin. In this case the content of functional groups is 0.01 to 5 percent by weight of the polymer or copolymer. The molecular weight of the resinous material is at least 10,000. Examples of such resinous materials are ADMER LF500, ADMER AT207T (Mitsui Petrochemical Ind., Co., Ltd., Japan), Modic H-20F, Modic H-400F and Mcdic L-400H (Mitsubishi Yuka KK, Japan). These are resinous materials are polyethylene with functional groups. Examples of more types of resinous Materials are ADMER QF500 and Modic P-300M which are polypropylene deals with functional groups.

The hose according to the invention is produced by extrusion. For example the polyamide, the rubber and the vulcanizing agent (crosslinking agent) placed in an extruder and 3 to 30 minutes at a temperature above the Melting point of the polyamide used is kneaded, forming a polyamide-rubber mixture with a phase structure in which the polyamide is the matrix phase and the vulcanized one Rubber present as a phase dispersed therein, is formed. The crowd will then with the resinous material of the polyolefin series containing functional Groups capable of reacting with the polyamide are coextruded. This resinous material material is fed into the extruder separately and heated to a molten state. With coextrusion, this becomes the outer layer Resin-like material constituting chemically to that constituting the inner layer Polyamide-rubber mixture bonded, creating an integrally connected hose.

The plastic tube formed in this way has the structure shown in FIG. 1 structure shown. Eventually it becomes one in a conventional manner For the practice desirable hose of the type shown in Fig. 2 processed.

A woven or non-woven is suitable as the reinforcement layer 4 Polyester textile material. Polyurethane resin is suitable as the upper protective layer 5, because it is very waterproof and has good abrasion resistance. However, you can for the layer 4 any types of fibrous materials and for the upper one Layer 5 rubbers derived from unsaturated polyesters can be used.

If necessary, the hose can be further protected by surrounds it with a metal foil or layer.

If the mixed polyamide-rubber compound constituting the inner layer is in which the polyamide is present as a matrix phase, in the molten state with the If the polyolefin material forming the outer layer is coextruded, the result is a Adhesiveness of the polyolefin material, which in comparison to similar polyamide compounds, as usual nylon blended with rubber, nylon copolymerized with rubber or plasticized nylon, is excellent. Thus, the peel strength is the inner layer from the outer layer in the plastic hose according to the invention significantly higher than with similar double-layer plastic hoses. In table I the results of comparative tests are compiled, in which the peel strength the inner layer (polyamide rubber compound) and the outer layer (polyolefin material) of the plastic hose of the invention with the corresponding values of conventional ones Plastic hoses are compared.

Table I Peel strength, inner layer test kg / 2.54 cm * 1 Comparative Example 1 nylon 12 3.2 Ir 2 plasticized * 2 nylon 12 2 1.8 11 3 nylon 12 / NBR mixture * 3 1.5 115 (non-crosslinked) Example 1 Nylon 12 / NBR mixture 3.1 (crosslinked) * 1 DAIAMID L-2140 (Daicel Chemical Industries, Ltd., Japan) * 2 DAIAMID L-2121 (15 Percent plasticized) (Daicel Chemical Industries, Ltd., Japan) * 3 DAIAMID L-2140 / N-220S mixture, N-220S (Japan Synthetic Rubber Co., Ltd., Japan).

This mixture is made by adding DAIAMID L-21 # 0 and N-220S in a mixing ratio of 50:50 (weight percent) using a 30 mm double extruder (L / D = 28) at a cylinder temperature of 200 ° C, a screw speed kneaded at 80 rpm and an extrusion rate of 5 kg / h.

14 DAIAMID L-2140 / N-220S mixture (cross-linked).

This crosslinked mixture is made by adding a mixture of DAIAMID L-2140 / N-220S (50:50 percent by weight) with m-phenylene-bis-maleimide added in an amount of 2 phr (parts per hundred) and the mixture under the kneaded in the aforementioned conditions.

Note 1: As a resinous polyolefin series material with functional H-20F (Mitsubishi Yuka KK, Japan) is used for groups.

Note 2: The test pieces of the samples used are made using a melt press under the following conditions: Temperature: 210 0C Pressure: 100 kg / cm2 Time: 3 min Note 3: The measurement is made at a cross-head speed of 50 mm / min using an autograph (Shimazu Seisakusho, Japan).

The plastic hose according to the invention is characterized by a special double-layer structure, which is used for fluorinated hydrocarbons (Freon) impermeable inner layer made of a cross-linked rubber-in-polyamide matrix and the water-impermeable outer layer made of the functional groups Resin-like material, the latter chemically forming an integral Hose is tied to the inner layer. Thus, the invention Plastic tubing not only has excellent flexibility, but it is also impermeable to fluorinated hydrocarbons and water.

This eliminates all of the disadvantages of conventional plastic tubing avoided. Because of these valuable properties, the one according to the invention is suitable Plastic hose, especially as a line for cooling media, such as fluorinated hydrocarbons (Freon), in automobile radiators and air conditioning systems.

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Claims (8)

Plastic hose claims 1. Plastic hose with double layer Structure characterized by - a polyamide-rubber mixture as the inner layer with a phase structure in which the polyamide is the matrix phase and the rubber is present as a disperse phase, this mixture by mixing the polyamide with the rubber in the presence of a vulcanizing agent, and - As the outer layer, a resin-like material from the polyolefin series, which is chemically bound to the polyamide-rubber mixture via functional groups contained therein is. 2. Plastic hose according to claim 1, characterized in that the polyamide is nylon 6, nylon 6-6, nylon 12, nylon 6-9, nylon 6-10, nylon 8 or a mixture or copolymer thereof. 3. Plastic hose according to claim 1, characterized in that the rubber is natural rubber, isoprene rubber, styrene-butadiene rubber, Acrylonitrile-butadiene rubber, isobutylene-isoprene rubber, chloroprene rubber, Ethylene propylene rubber, chlorinated polyethylene, chlorinated polyethylene, Acrylic rubber, epichlorohydrin rubber, urethane rubber, silicone rubber, fluororubber, Butadiene rubber, modified types of rubber of the aforementioned types of rubber with a content of carboxyl or epoxy groups and mixtures of these rubbers acts. 4. Plastic hose according to claim 3, characterized in that The rubber is a mixture of acrylonitrile-butadiene rubber and epichlorohydrin rubber acts. 5. Plastic hose according to claim 1, characterized in that the vulcanizing agent is capable of vulcanizing the rubber during the Mixing temperature can be achieved within 3 to 30 minutes. 6. Plastic hose according to claim 5, characterized in that the vulcanizing agent is m-phenylene bis-maleimide, a mixture of m-phenylene-bis-maleimide and dibenzothiazyl disulfide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne-3 or Phenolic resins. 7. Plastic hose according to claim 1, characterized in that 30 to 70 percent by weight polyamide to 70 to 30 percent by weight rubber is used have been. 8. Plastic hose according to claim 1, characterized in that the resinous material of the polyolefin series is a polymer or copolymer of ethylene, propylene and / or butylene, the total amount of ethylene, Propylene and / or butylene at least 50 percent by weight, based on the polymer or copoly- merisat, amounts and functional groups with the polyamide are reactive, in the molecular chain in an amount of 0.01 to 5 percent by weight, based on the polymer or copolymer, are included.