EP3938208A1

EP3938208A1 - Coolant hose

Info

Publication number: EP3938208A1
Application number: EP20702977.8A
Authority: EP
Inventors: Alexandra Brandt; Michael Sont
Original assignee: ContiTech Techno Chemie GmbH
Current assignee: ContiTech Techno Chemie GmbH
Priority date: 2019-03-11
Filing date: 2020-01-27
Publication date: 2022-01-19
Also published as: WO2020182360A1; DE102019203254A1; CN113795382A; US20220186858A1

Abstract

The invention relates to a coolant hose having at least the following layer structure: - an inner layer (A) that acts as barrier layer and is formed from at least two plies (A1, A2), wherein at least one ply (A1) is formed from an elastomer-modified EVOH or a polyolefin-modified EVOH or of a combination of an elastomer-modified EVOH and a polyolefin-modified EVOH and - at least one strength member layer (B) and - an outer layer (C) formed from at least one elastomeric material.

Description

description

Refrigerant hose

The invention relates to a refrigerant hose, at least the following

Layer structure has:

- an inner layer that acts as a barrier layer and consists of at least two layers

is constructed and

- At least one reinforcement layer and

- An outer layer which is composed of at least one elastomeric material.

Refrigerant hoses that are installed in air conditioning systems for the automotive industry are usually filled with fluorocarbons as refrigerants. When released into the atmosphere, this type of refrigerant has a negative impact on the Elm world, for example in the form of acid rain, the greenhouse effect or the depletion of the ozone layer. CO ₂ is a more environmentally friendly refrigerant. Due to its molecular size and its physico-chemical properties, however, it places higher demands and challenges on the air conditioning system, which must be met or solved by new hose systems, among other things.

Hoses that are used for conventional refrigerants usually consist of three different layers: an inner layer, a reinforcement layer and an outer layer, whereby the outer layer and the inner layer are usually made of an elastomeric material and the inner layer is often multi-layered, plus one layer made of a thermoplastic material, which significantly improves the barrier properties of the hose with regard to refrigerant loss, but at the same time worsens the flexibility of the hose. EPDM, EPM, BIMS, BIIR, CIIR, IIR, CM, AEM, ACM, CR, NBR, HNBR alone or in combination can be used as elastomers for the inner layer and / or the outer layer. The reinforcement layer usually consists of organic fiber systems, such as

Polyester, polyamide, rayon, aramid or PVOH yarn and is usually braided or spiraled, i.e. wrapped shape. In the case of a spiral hose, two reinforcement layers are usually used, which are the same or

can be different from each other. A further elastomer layer can be integrated as an intermediate layer between the two wound fiber layers. In order to generate or optimize the adhesion between the different layers, additional adhesion promoter layers can be added to the hose structure.

The thermoplastic layer of the inner layer can either be inside the tube (veneer tube also, see FIGS. 1 and 2) or it can be embedded as a barrier layer between two further layers of the inner layer (barrier tube also, see FIGS. 3 and 4). Polyamides have proven themselves as the material for the barrier layer. In particular, impact-modified PA.6 grades are used because of their good compromise between flexibility and

Barrier function used nowadays for the manufacture of air conditioning hoses.

The hose structure described above gives the hose enough flexibility to be laid and installed in a narrow space and at the same time has sufficiently good barrier properties, e.g. to counteract a loss of refrigerant of refrigerants R134a (1,1,2-tetrafluoroethane) or R1234yf (2,3,3,3-tetrafluoropropene) to an adequate extent.

As already mentioned above, the hose structure mentioned must be redesigned for use with CO2 as a refrigerant, since the common air conditioning hoses do not have a sufficient barrier function against CO2.

To optimize the barrier function, i.e. to further avoid the

Loss of refrigerant, it is proposed in US20040118469A1 to use a layer based on EVOH which, compared to PA.6, has a significantly better barrier property.

However, this type of hose has deficits in flexibility and dynamic

mechanical loads. Cracks form relatively quickly in the EVOH layer due to impulses or during cold flexibility tests. The object of the present invention is therefore to provide a refrigerant hose which, on the one hand, has an inner layer resistant to the refrigerant, in particular to CO2, with an optimized barrier effect and, on the other hand, has sufficient flexibility and high resistance to dynamic

mechanical loads.

This task is achieved by a refrigerant hose that has at least the following layer structure:

is constructed, at least one layer being constructed from an elastomer-modified EVOH or a polyolefin-modified EVOH or from a combination of an elastomer-modified EVOH and a polyolefin-modified EVOH, and

- At least one reinforcement layer and

- An outer layer which is composed of at least one elastomeric material.

Surprisingly, it has been shown that when using a specially

modified EVOH results in increased flexibility and an associated improved dynamic-mechanical resistance compared to unmodified EVOH.

According to the invention, the barrier layer is made up of at least two layers and has at least one layer which is made up of an elastomer- or polyolefin-modified EVOH or a combination of the two. This layer forms the so-called barrier layer of the hose. The EVOH contained in the barrier layer

(Not counting elastomer or polyolefin content from the modification)

Ethylene content between 10 and 44%, with a lower proportion between 27 and 29% being preferred in order to keep the barrier effect and also the melting point as high as possible. The modified EVOH contains 5 to 40% by weight of elastomer or polyolefin or a combination of both, with 10% by weight of elastomer preferably being selected in order to give the EVOH sufficient flexibility or impact modification on the one hand, but at the same time the barrier effect of the entire material as possible up to hold. The elastomer for the modification is preferably a non-polar elastomer, which is also either completely or partially

is connection modified in order to be able to enter into a homogeneous bond with the EVOH. Particularly good results can be achieved when using a maleic anhydride-grafted elastomer. However, further modifications of the elastomer or polyolefin by other functional groups are also conceivable, as long as these can form a bond with the EVOH.

For a good compromise between sufficient barrier effect and rigidity of the hose, the barrier layer preferably has a layer thickness between 0.02 and 0.3 mm.

In addition to the barrier layer described, the barrier layer, which is also referred to below as the inner layer, also contains at least one further second layer. As polymer materials for this second layer, polyamides, polyolefins,

thermoplastic elastomers and elastomers and combinations thereof can be used. These can include the following materials: PP, PE, PMP, TPC, PA6, PA66, PA11, PA12, PA46, PA610, PA9T, PA6T, EPM, EPDM, BR, IIR, BIIR,

CIIR, BIMS. If a polyamide is used, this is preferred

impact modified, e.g. through reactive extrusion with a maleic anhydride-grafted polyolefin to increase the flexibility of the material and to prevent cracks from forming under mechanical stress (e.g. with impulse or hose reinforcement)

to counteract.

The further second layer preferably has a layer thickness between 0.05 and 0.5 mm, particularly preferably between 0.15 and 0.3 mm.

In a particularly preferred embodiment, the inner layer consists of the two layers mentioned, whereby the further second layer, which forms the innermost layer of the hose, serves as a protective layer for the barrier layer, can also make a positive contribution to the barrier function of the barrier layer, depending on the choice of material. Depending on

Material selection, a connection modification of the material is necessary in order to be able to enter into adhesion with the barrier layer. This can also be achieved, for example, by maleic anhydride grafting. In a further particularly preferred embodiment, the inner layer consists of three layers, the further second layer, which forms the innermost layer of the hose, serving as a protective layer for the barrier layer (analogous to the two-layer structure of FIG

Inner layer) and the additional third layer is preferably composed of at least one elastomer. EPDM, EPM, BIMS, BIIR, CIIR, IIR, CM, AEM, ACM, CR, NBR or HNBR or combinations of the above are preferably used as elastomers. The barrier properties of the additional third layer can be increased by adding layered silicates, graphene or other plate-like fillers with a high

Aspect ratio can be optimized. The third layer is preferably in extruded form.

If there is an additional third layer, this preferably has a layer thickness between 0.2 and 2 mm, particularly preferably between 0.2 and 0.5 mm.

The hose according to the invention also contains at least one reinforcement layer and an outer layer, i.e. Outer layer.

The reinforcement layer is applied by braiding or spiraling. A knitted fabric is also possible for areas of application with low pressure requirements. Aramids, such as p-aramid or m-aramid, polyamides, PET or PVOH, are preferably suitable as the material for the reinforcement layer, depending on the pressure requirements

Combinations of the above in the form of hybrid systems.

According to the invention, the outer layer is composed of at least one elastomeric material, which can preferably be EPDM, EPM, BIMS, BIIR, CIIR, IIR, CM, AEM, ACM, CR, NBR or HNBR or combinations thereof. The barrier properties of the outer layer can be optimized by adding layered silicates, graphenes or other plate-shaped fillers with a high aspect ratio. The outer layer is preferably in extruded form.

The outer layer preferably has a layer thickness between 0.2 to 2 mm, particularly preferably between 0.7 and 1.5 mm. In a particularly preferred embodiment, the refrigerant hose also contains at least one intermediate layer. The intermediate layer is preferably composed of at least one elastomeric material, advantageously EPDM, EPM, BIMS, BIIR, CIIR, IIR, CM, AEM, ACM, CR, NBR or HNBR or

Combinations of these can act. The barrier properties of the intermediate layer can be optimized by adding layered silicates, graphenes or other plate-shaped fillers with a high aspect ratio. The intermediate layer is preferably in extruded form.

The intermediate layer preferably has a layer thickness between 0.1 and 1.5 mm, particularly preferably between 0.2 and 0.7 mm.

There is preferably a sufficiently good adhesive bond between all layers, which in a preferred embodiment is provided by the integration of thin adhesive layers between the layers and / or between the layers.

The individual plies and / or layers of the refrigerant hose are preferably applied to a mandrel in extruded form. The hose is then vulcanized or partially vulcanized and thorned. The partially vulcanized hose can be used for molded hose production and is vulcanized to the end in the molding process.

The invention will now be explained using an exemplary embodiment with reference to test results and schematic drawings.

Test results

Table 1 shows various physical test results using a

Refrigerant hose from the prior art VI and a refrigerant hose according to the invention El. The test results were determined using DIN Spec 74106. The rating “+” means that the test was passed, the rating means that the test was not passed. The hose structure was as follows:

Another second inner layer A2: PA6 (Orgalloy LT5050, Arkema company), layer thickness 0.3 mm

Barrier layer A1: elastomer-modified EVOH (Eval LA170B, from Kuraray) (El) or unmodified EVOH (Evasin 2951F, from Arkema) (VI), layer thickness 0.1 mm Additional third inner layer A3: BIIR, layer thickness 1.1 mm

Reinforcement layer B: p-aramid, braided

Outer layer C: EPM, layer thickness 0.85 to 1mm

Table 1

The inventive refrigerant hose E1 is suitable as a refrigerant hose for use in the low-temperature areas of an air conditioning system (currently max. 130 ° C.) and CO2 as the refrigerant. It is characterized by high barrier properties,

Media resistance to compressor oils, good cold flexibility and good impulse behavior. The comparison hose VI with the unmodified EVOH fails after a short pulse and does not show any high flexibility at low temperatures.

Schematic Drawings Fig. 1 shows a refrigerant hose in the form of a veneer hose from the prior art with a braided reinforcement layer B, a two-layer structure of the Inner layer A, in which the thermoplastic layer A1 of the inner layer A consists of polyamide and, as a barrier layer, forms the innermost layer of the inner layer A, another second layer A2 of the inner layer A and an outer layer C.

Fig. 2 shows a refrigerant hose in the form of a veneer hose from the prior art with two spiralized reinforcement layers B1, B2, a two-layer structure of the inner layer A, in which the thermoplastic layer A1 of the inner layer A consists of polyamide and the innermost as a barrier layer Layer of the inner layer A forms, another second layer A2 of the inner layer A, an additional elastomeric

Intermediate layer D and an outer layer C.

Fig. 3 shows a refrigerant hose in the form of a barrier hose from the prior art with a braided reinforcement layer B, a three-layer structure of the inner layer A, in which the thermoplastic layer A1 of the inner layer made of polyamide as a barrier layer between two further layers A2, A3 the inner layer A is embedded, a further second layer A2 of the inner layer A, an additional third layer A3 of the inner layer A and an outer layer C.

Fig. 4 shows a refrigerant hose in the form of a barrier hose from the prior art with two spiralized reinforcement layers B1, B2, a three-layer structure of the inner layer A, in which the thermoplastic layer A1 of the inner layer A made of polyamide as a barrier layer between two further layers A2, A3 of the inner layer A is embedded, a further second layer A2 of the inner layer A, an additional third layer A3 of the inner layer A, an additional elastomeric intermediate layer D and an outer layer C.

Fig. 5 shows a refrigerant hose according to the invention with a braided or knitted reinforcement layer B, a three-layer structure of the inner layer A, in which the barrier layer A1 of the inner layer A made of elastomer-modified EVOH or polyolefin-modified EVOH is embedded between two further layers A2, A3 of the inner layer A, one a further second layer A2 of the inner layer A, an additional third layer A3 of the inner layer A, and an outer layer C. The materials of the two further layers A2, A3 of the inner layer A are different from the material of the barrier layer Al. 6 shows a refrigerant hose according to the invention with two spiralized reinforcement layers B1, B2, a three-layer structure of the inner layer A, in which the barrier layer A1 of the inner layer A made of elastomer-modified EVOH or polyolefin-modified EVOH is embedded between two further layers A2, A3 of the inner layer A, a further second layer A2 of the inner layer A, an additional third layer A3 of the inner layer A, an additional intermediate layer D and an outer layer C. The materials of the two further layers A2, A3 of the inner layer A are different from the material of the barrier layer.

List of reference symbols

(Part of the description)

A inner layer

Al barrier layer of the inner layer

A2 further second layer of inner layer A3 additional third layer of inner layer B single reinforcement layer B1 first reinforcement layer

B2 second reinforcement layer D elastomeric intermediate layer

C outer layer

Claims

1. Refrigerant hose that has at least the following layer structure:

- An inner layer (A), which acts as a barrier layer and is composed of at least two layers (Al, A2), at least one layer (Al) being composed of one

elastomer-modified EVOH or a polyolefin-modified EVOH or a combination of an elastomer-modified EVOH and a

polyolefin-modified EVOH and

- At least one reinforcement layer (B) and

- An outer layer (C) made of at least one elastomeric material

is constructed.

2. Refrigerant hose according to claim 1, characterized in that the inner layer (A) consists of two layers (Al, A2).

3. Refrigerant hose according to claim 1, characterized in that the inner layer (A) consists of three layers (Al, A2, A3).

4. Refrigerant hose according to one of claims 1 to 3, characterized in that the EVOH contained in the modified EVOH has an ethylene content between 10 and 44 mol%.

5. Refrigerant hose according to one of claims 1 to 4, characterized in that the elastomer component in the modified EVOH contains a bondable elastomer or consists entirely of it.

6. refrigerant hose according to claim 5, characterized in that the

bindable elastomer is a non-polar elastomer.