MXPA00003116A - Composite thermoplastic-elastomer product - Google Patents

Abstract

The invention concerns a composite thermoplastic-elastomer product, in particular a pipe for transporting refrigerating fluid for a motor vehicle air-conditioning circuit, comprising an inner layer (10) formed by a plastic alloy comprising a polyamide (6) and at least 51%of a modifying agent selected among ethylene-acrylate-acrylic acid terpolymers and a layer (12) formed by a mixture of an elastomer such as a brominated butyl rubber modified by a grafted polybutadiene-vinyl-1,2, a silane, an ethylene-acrylic acid copolymer or a maleic anhydride grafted ethylene-propylene copolymer, with total adherence between the thermoplastic and the elastomer.

Description

PRODUCT OF MIXED THERMOPLASTIC / ELASTOMERIC MATERIAL The invention relates to a thermoplastic / elastomer composite material such as, for example, a hose for transporting a refrigerant for an automobile air conditioning circuit. These products must comply with increasingly stringent standards, especially with regard to their thermal behavior (both internal and external), their resistance to resistance agents and, when they are hoses, their impermeability with respect to the transported fluid. In addition, their life time must be as great as possible and their sealing and waterproofing properties can be maintained during this lifetime.The production of thermoplastic / elastomeric mixed material hoses for transporting fluids in the industry has been proposed many times. automotive, these hoses generally have an inner layer of polyamide, an elastomeric layer covering the polyamide, a textile reinforcement and an outer protective layer made of rubber or elastomer.In these known hoses, it is often necessary to form a compromise between the desired flexibility and the impermeability of the transported fluid and, therefore, a thin layer of an adhesive material can be placed between the thermoplastic and the elastomer in order to ensure that they adhere to one another. a circuit of air conditioning, it is necessary to improve the impermeability to the fluid transported or (the refrigerants that have been used up to now and containing the CFCs are being replaced by the HFCs known by the name R134a, these being combined with a polyalkylene glycol type lubricant) and a mixture has been proposed, for example. of a polyamide, a graft-modified polyolefin and e-caprolactam for this inner layer, but this composition does not adhere to the layer of the elastomer that covers it. In addition, the amount of e-caprolactam used is a compromise between fluid flexibility and impermeability, the addition of e-caprolactam makes it possible to improve the flexibility to the detriment of waterproofing. This is the reason why the Applicant gives himself the task of providing a product of mixed material that meets the best practical requirements, especially in that there is complete adhesion between the thermoplastic and the elastomer as well as the impermeability excellent in transported fluids (in the case of a hose) and especially in the new refrigerants used in automotive air conditioning circuits. For this purpose, the invention proposes a mixed material product comprising an inner layer of a mixture of a thermoplastic and a modifier, the layer being covered with a layer of a mixture of an elastomer of a modifier, wherein: the inner layer it essentially consists of an alloy of plastics comprising a thermoplastic selected from polyamides (PA) and at least one modifier chosen from ethylene-acrylate-acrylic acid terpolymers, the proportions of thermoplastic / ethylene-acrylate-acrylic acid terpolymers it is between 10/90 and 49/51 (by weight); and the elastomer is selected from natural rubber (polyisoprene or NR), synthetic polyisoprene (IR), nitrile rubbers (NBR); halogenated nitrile rubbers, hydrogenated nitrile rubbers, epichlorohydrin-ethylene oxide copolymers (ECO), ethylene-acrylic acid elastomers, butyl rubber (isoprene-isobutylene or IIR copolymers), halogenated butyl rubber (XIIR), elastomers of isobutylene-p-methylstyrene para-brometylstyrene, ethylene-propylene-diene terpolymers (EPDM) and ethylene-propylene copolymers (EPM), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), chlorosulfonated polyethylene having side groups of alkyl (ACSM), polychloroprene (CR), acrylic polymer (ACM), ethylene-vinyl acetate copolymers (EVA) and ethylene-acrylate copolymers (EAM), at least one modifier, which modifies the elastomer, being chosen from between 1,2-vinyl polybutadienes grafted with maleic anhydride, epoxidized and / or hydroxylated polybutadienes, silanes, ethylene-acrylic acid elastomers and ethylene-propylene copolymers grafted with maleic anhydride.

According to the invention, the polyamide is selected from the group consisting, inter alia, of nylon-6, nylon-6,6, nylon-11, nylon-12, nylon-6/10 and nylon-6/12. It has been found that, in these products, complete adhesion exists between the thermoplastic and the elastomer without the use of an internal layer of an adhesive being necessary, and that it is impossible to separate the thermoplastic and elastomeric layers without destroying them. It has also been found that to the extent that the proportions of the modifiers in the thermoplastic are always greater than the quantities of the thermoplastic, they form with the latter an alloy of plastics whose manufacture is significantly improved since it is possible to obtain a much more homogeneous dispersion than that obtained with the modified thermoplastics of the prior art, in which the amounts of modifiers are generally smaller than those of thermoplastics; said homogeneous dispersion makes it possible, in particular, to obtain very poor manufacturing components by extrusion, the elastomer and / or the thermoplastic advantageously includes various modifiers. The proportions of modifiers in the elastomer can vary widely and are, in general, between 0.5 and 50% approximately.

The thermoplastic and / or the elastomer used may also include at least organic or inorganic fillers, as well as the usual plasticizers. The invention also proposes a hose for transporting a refrigerant for an air conditioning circuit for automobiles, comprising an inner layer of the thermoplastic and a layer of the elastomer that is described, in which the thickness of the hose of the inner layer of the thermoplastic is about 0.05 to 2 mm, that of the elastomer layer is about 0.2 to 3 mm. Said hose also includes one or more textile reinforcement layers that cover the elastomer layer and cover itself with a protective layer made of elastomer. A thin layer of elastomer can also be provided on the inner face of the thermoplastic layer, in order to provide a seal when the hose is fixed to a connecting nozzle. In a preferred embodiment of the invention, the thermoplastic mentioned above is a mixture of 35 to 45% (w / w) of polyamide, preferably nylon-6, and 55 to 65% (w / w) of an ethylene terpolymer. acrylate-acrylic acid. The invention will be better understood and other aspects, details and advantages thereof could appear more clearly on reading the following description, given by an example form with reference to the accompanying drawings in which: Figure 1 is a schematic partial view, in cross section, of a product of mixed material according to the invention; Figure 2 is a partial, perspective, schematic view of a hose according to the invention. The mixed material product according to the invention, which is shown schematically in Figure 1, comprising a layer 10 of the thermoplastic covered with a layer 12 of the elastomer, the adhesion of these two layers to one another feel any attempt to separate these two layers resulting from the destruction of one and / or both of these layers. The thermoplastic of the layer 10 can be chosen from the following compounds: PA-6, PA-6,6, PA-11, PA-12, PA-6/10 and PA-6/12, as a mixture with a terpolymer of ethylene-acrylate-acrylic acid in proportions between 10/90 and 49/51 (w / w). This modifier can optionally be combined with other modifiers. The layer 12 of the elastomer is based on an elastomer chosen from the following compounds, NR, IR, NBR, XNBR, HNBR, ECO, EPDM, EPM, CM, CSM, ACSM, CR, ACM, EVA, EAM, ethylene copolymer Acrylic acid, butyl rubber, halogenated butyl rubber and isobutylene-p-methylstyrene para-bromomethylstyrene, with the addition of at least one of the following modifiers: a polybutadiene of 1, 2-vinyl grafted with maleic anhydride or with another carboxylic acid anhydride, or epoxidized and / or hydroxylated polybutadienes and ethylene-propylene copolymers grafted with maleic anhydride. Several of these modifiers, which modify the elastomers, can be added in a proportion between 0.5 and 50% by weight. The hose shown schematically in Figure 2 is intended to convey a refrigerant of the HFC type used in automotive air conditioning circuits and comprising an inner layer 10 of the thermoplastic having the same composition as layer 10 in Figure 1, a layer 12 of surrounding elastomer of the layer 10 of the thermoplastic and having the composition of the layer 12 in Figure 1, a textile reinforcement 14 surrounding the layer 12 of the elastomer, this textile reinforcement possibly being a braid of polyester threads, polyamide yarns, etc., and a protective layer 16 made of a suitable elastomer which may be of the same type as that of layer 12 or different. Normally, the thickness of the inner layer 10 based on the thermoplastic is approximately 0.1 to 0.3 mm and that of the layer 12 based on the elastomer is approximately 0.5 to 2 mm. A thin layer of elastomer can cover the inner surface of the layer 10 based on the thermoplastic in order to improve the sealing when the hose is fixed in a connecting nozzle or the like.

For example, the composition of layer 10 and 12 of the hose in Figure 2 may be as follows: layer 10: - PA-A 41 parts by weight - ethylene-acrylate-acid terpolymer 59 parts by weight acrylic (DU PONT DE NEMOURS (ZYTEL® ST 7301) or BASF (LUCALEN® 2920), for example) - layer 12: • Brominated butyl rubber 100 parts by weight • black carbon 80 parts by weight • reactive phenolic resin 9 parts by weight • Plasticizer 5 parts by weight • 1,2-vinyl polybutyldiene grafted 5 parts by weight with maleic anhydride - para-bromomethylstyrene of isobutyl-p- 100 parts by weight methylstyrene • black carbon 80 parts by weight • plasticizer 5 parts by weight • ZnO 2 parts by weight • ZDBC 2 parts by weight • 1,2-vinyl polybutadiene grafted 5 parts by weight with maleic anhydride

Claims (10)

1. CLAIMS 1. A mixed material product comprising (10) a mixture of a thermoplastic and a modifier, the layer being covered with a layer (12) of a mixture of an elastomer and a modifier, wherein: the layer (10) essentially consists of a plastic alloy comprising a thermoplastic selected from polyamides (PA) and at least one modifier selected from ethylene-acrylate-acrylic acid terpolymers, the proportions of the thermoplastic / ethylene-acrylate terpolymers acrylic acid being between 10/90 and 49/51 (by weight); and the elastomer is selected from natural rubber (polyisoprene or NR), synthetic polyisoprene (IR), nitrile rubbers (NBR); halogenated nitrile rubbers, hydrogenated nitrile rubbers, epichlorohydrin-ethylene oxide (ECO) copolymers, ethylene-acrylic acid elastomers, butyl rubber (isoprene-isobutylene or MR copolymers), halogenated butyl rubber (XIIR), elastomers of isobutylene-p-methylstyrene para-brometylstyrene, ethylene-propylene-diene terpolymers (EPDM) and ethylene-propylene copolymers (EPM), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), chlorosulfonated polyethylene having side groups of I rent (ACSM), polychloroprene (CR), acrylic polymer (ACM), ethylene-vinyl acetate (EVA) copolymers and ethylene-acrylate copolymers (EAM), at least one modifier, which modifies the elastomer, being chosen from polybutadienes of 1,2-vinyl grafted with maleic anhydride, epoxidized and / or hydroxylated polybutadienes, silanes, ethylene-acrylic acid elastomers and ethylene copolymers -propylene grafted with maleic anhydride.
2. 2. The product according to claim 1, the polyamide is selected from the group consisting of nylon-6, nylon-6,6, nylon-11, nylon-12, nylon-6/10 and nylon-6/12.
3. 3. The product according to claim 1 or claim 2, wherein the ratio of the modifier in the elastomer is between 0.5 and 50% by weight approximately.
4. 4. The product according to any of claims 1 to 3, wherein the elastomer and / or the thermoplastic include several of the modifiers mentioned above.
5. The product according to one of the preceding claims, wherein the thermoplastic and / or the elastomer includes at least fillers, either organic or inorganic and / or plasticizers.
6. 6. The product according to any one of the claims, wherein the aforementioned thermoplastic is a mixture of 35 to 45% (w / w) of polyamide, preferably nylon-6 and 55 to 65% (w / w) of an ethylene-acrylate-acrylic acid terpolymer.
7. 7. A hose for transporting a refrigerant for an automobile air conditioning circuit, comprising an inner layer of thermoplastic covered with an elastomer layer having the compositions described in the preceding claims, wherein the thickness of the layer 10 of the thermoplastic is approximately 0.05 to 2 mm and the layer (12) of the elastomer is approximately 0.2 to 3 mm.
8. The hose according to claim 7, wherein the layer (12) of the elastomer is covered with at least one textile reinforcement layer (14) and with a protective layer (16), for example made of an elastomer .
9. The hose according to claim 7 or 8, which also comprises a thin layer of elastomer from 0.2 to 3 mm thick on the inner side of the layer (10) of the thermoplastic.
10. 10. The hose according to one of the claims 7 to 9, wherein the plastic alloy of the inner layer (10) is a mixture of nylon-6 and at least one terpolymer of ethylene-acrylate-acrylic acid, the elastomer of the layer (12) covering the thermoplastic being based on modified isobutylene-p-methylstyrene para-bromomethylstyrene by at least one 1,2-vinyl polybutadiene grafted with maleic anhydride.