JPH04151087A - Hose for conveying refrigerant - Google Patents

Abstract

PURPOSE:To provide excellent gas permeability and heat resistance and to prevent the occurrence of interlayer peel by providing inner and outer pipe layers and a fiber-reinforced layer formed therebetween, forming an inner layer by using polyamide resin, and forming an adhesion layer of a composition of a chlorine-containing polymer, polyisocyanate, and hydrotalcite between the inner and outer layers of the inner pipe layer. CONSTITUTION:A fiber-reinforced layer 6 is located between inner and outer pipe layers 2 and 4, the inner pipe layer 2 is of two-layer and comprises inner and outer inner pipe layers 8 and 10. The inner pipe layer 8 on the inner side of the inner pipe layer 2 is formed of a polyamide resin material, and the outer inner pipe layer 10 is formed of a rubber material. The inner and outer inner pipe layers 8 and 10 are adhered together through the medium of an adhesion layer 12. The composition of the adhesion layer 12 is prepared such that, based on 100 pts.wt. a solid, 5-35 pts.wt.. a chlorine-contained polymer being a chlorine amount, 2 or more pts.wt. polyisocyanate, and 5 or more pts.wt. hydrotalcite are blended. As a result, excellent gas non-permeability is provided, interlayer peel is prevented from occurring, and heat resistance is sharply improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a refrigerant transport hose, and particularly to a hose that can be suitably used as a piping hose for automobile car coolers, air conditioners, and the like.

(Background technology) Conventionally, chlorofluorocarbon gas (dichlorodifluoromethane: R
Hoses for transporting refrigerants, such as 12), have a three-layer structure integrally consisting of an inner pipe layer, an outer pipe layer located outside the inner pipe layer, and a fiber reinforced layer interposed between these two layers. It has been known. In such hoses, the inner tube layer is generally made of acrylonitrile-butadiene copolymer (NBR) or chlorosulfonated polyethylene (C3M), and the fiber reinforcement layer is made of polyester fiber or rayon fiber. The outer tube layer is made of an elastomer or an elastomer obtained from an ethylene-propylene-nonconjugated polyene (diene) terpolymer. It is made of rubber-like elastic material (EPDM) or chloroprene rubber (CR). Spiking holes extending from the outer surface to the fiber reinforced layer are provided at appropriate locations on the outer tube layer, allowing the refrigerant gas that has permeated through the inner tube layer to escape to the outside through the spiking holes. This prevents it from accumulating between the layers of the hose. This is because if the permeated gas stays in the glabellar area of the hose, that area will swell and cause separation between the glabella.

By the way, such refrigerant transport hoses are entirely made of rubber material except for the fiber reinforcement layer, so they are (a) flexible and easy to pipe, and (b) easy to connect to fittings such as nipples. It has the advantage of good sealing properties and maintains airtightness, but on the other hand, rubber materials generally have gas permeability, so when using low molecular weight gases such as chlorofluorocarbon gas as a refrigerant, , which has the inherent problem of gas leakage.

In particular, NBR and C3 used as constituent materials of the inner tube layer.
Rubber materials such as M have high gas permeability.

Therefore, in response to the recent social problem of depletion of the atmospheric ozone layer due to fluorocarbon gas, we have decided to use non-polluting fluorocarbon gas.
For example, 1,1. l,2-tetrafluoroethane: R1
34a, etc.), the reduction of the amount of fluorocarbon gas permeation through refrigerant transport hoses has become the most important issue.

Under these circumstances, a hose with a multi-layered inner tube layer, the innermost layer of which is made of a polyamide resin with excellent fluorocarbon gas impermeability, has been considered, and this eliminates the gas leakage problem described above. Studies are underway to improve the refrigerant and to make it compatible with newly developed refrigerants (R134a, etc.). However, in this case, adhesion between the polyamide resin layer and the adjacent rubber layer such as NBR is an important requirement, and in order to bond these two layers well, for example,
In Japanese Patent Publication No. 61-21134, a synthetic resin layer and NB
A manufacturing method has been proposed in which an adhesive containing an elastomer such as resorcinol-formalin and NBR is interposed between an unvulcanized rubber layer such as R or the like.

On the other hand, it is also desired that hoses for transporting refrigerant have improved heat resistance. In other words, compressors for automobiles, automobiles, and car air conditioners have made remarkable progress in recent years. This is because the environmental temperatures in which they are used are becoming increasingly severe. Therefore, N with low heat resistance
When BR is applied to the outer portion of the inner tube layer adjacent to the polyamide layer, a problem arises in that the heat resistance is insufficient.

Furthermore, the above-mentioned alternative chlorofluorocarbon gas (
The water absorption amount of R134a) is higher than that of conventional fluorocarbon gas (R1
2), therefore, a rubber material with good water impermeability is desired as the rubber material applied to the outer portion of the inner tube layer.

From this point of view, the use of nonpolar rubbers such as EPDM, EPM, IIR, and halogenated IIR has been studied as rubber materials that satisfy both heat resistance and moisture impermeability.

Therefore, these non-polar rubbers are suitable for boat fishing because they have poor vulcanization adhesion with polyamide resins, so between these two layers, there is a need to have good adhesion to both polyamide resins and non-polar rubbers. A method of interposing an adhesive has been adopted, and a chlorinated rubber-based elastomer adhesive is suitably used as an adhesive that has good adhesion to non-polar rubber. However, chlorinated rubber-based elastomer adhesives have the inherent problem of causing a dechlorination reaction when excessive heat is applied, and as a result, there was a risk that the adjoining polyamide-based resin would be adversely affected. be. Therefore, as mentioned above, it has been difficult to use it in an engine room or the like where the temperature is high.

In this way, conventional refrigerant transport hoses all have advantages and disadvantages, and in response to the various demands for improved performance in recent years,
None of them were satisfactory in terms of quality.

(Solving Division B) Against this background, the present invention was made, and the problem to be solved is to provide a material with excellent gas impermeability to low molecular weight gases such as chlorofluorocarbon gas and excellent heat resistance. Another object of the present invention is to provide a refrigerant transport hose that does not cause the problem of peeling between the eyebrows.

(Solution Means) In order to solve the above problems, the present invention includes:
It comprises an inner tube layer, an outer tube layer located outside the inner tube layer, and a fiber reinforcing layer interposed between both layers, and the inner tube layer is composed of at least two layers, an inner layer and an outer layer. In the hose in which the inner layer is formed of a polyamide resin, the amount of chlorine between the inner layer and the outer layer of the inner tube layer is 5 to 35 parts by weight per 100 parts by weight of solid content. It has an adhesive layer made of a composition containing a chlorine-containing polymer in a proportion of 2 parts by weight or more, a polyisocyanate in a proportion of 2 parts by weight or more, and a hydrotalcite in a proportion of 5 parts by weight or more. The gist of the present invention is a refrigerant transport hose characterized in that the inner layer and the outer layer are integrally bonded.

(Function/Effect) That is, in the present invention, by forming the inner layer of the hose inner tube layer with polyamide resin, excellent gas impermeability is ensured, while the inner layer and the hose inner tube layer are made of polyamide resin. by adhering them to the outer layer of the skin via an adhesive layer made of the composition as described above, to effectively prevent peeling between the eyebrows,
The heat resistance of the entire hose was also significantly improved. More specifically, since the composition constituting the adhesive layer contains a predetermined amount of chlorine, it has at least a certain level of heat resistance and adhesion. Furthermore, by adding a predetermined amount of polyisocyanate to the composition, the adhesion is effectively improved, and by adding a predetermined amount of hydrotalcite. As a result, heat resistance is significantly improved.

Therefore, the gas impermeability of the formed hose as a whole,
Both heat resistance and adhesion can be significantly improved, and the hose according to the present invention has extremely high practical value as a hose that satisfies all the properties required for a refrigerant transport hose. be.

(Specific Configuration) By the way, FIG. 1 shows an example of a refrigerant transport hose having a structure according to the present invention. In the same figure, 2
is an inner tube layer, 4 is an outer tube layer, and a fiber reinforced layer 6 is interposed between the inner tube layer 2 and the outer tube layer 4 to form an integrated refrigerant transport hose. be. and,
The inner tube layer 2 further has two layers, an inner inner tube layer 8.
and an outer inner tube layer 10.

The inner inner tube layer 8, which is one layer constituting the inner tube layer 2, is
It is made of a polyamide resin material that is highly impermeable to fluorocarbon gas, thereby effectively preventing gas leakage from the hose. Note that polyamide resins include nylon 6 and nylon 11.
, nylon 12, nylon 612, blends of nylon 6 and nylon 66, blends of nylon 6, nylon 66, and nylon 610, as well as various blends containing these as main components.

On the other hand, as the material for forming the outer inner tube layer 10, which is another layer constituting the inner tube layer 2, any of various rubber materials conventionally used as inner tube layer forming materials may be used. Among them, EPDM, EPM, IIR, Cf-11
Rubber materials such as halogenated IIR such as R can be preferably used because they have excellent heat resistance and moisture impermeability.

In the present invention, the inner inner tube layer 8 and the outer inner tube layer 10 are bonded to each other via an adhesive layer 12, and are configured as an integral inner tube layer 2.

Here, the composition constituting the adhesive layer 12 is one in which a chlorine-containing polymer is blended as an adhesive raw material, and this chlorine-containing polymer is dissolved in a predetermined solvent as a solution type adhesive. It is prepared as an emulsion-type adhesive or dispersed in a predetermined dispersion medium. More specifically, the chlorine-containing polymer is blended in an amount of 5 to 35 parts by weight per 100 parts by weight of the solid content of the composition, and the polyisocyanate is further blended in an amount of 2 parts by weight or more, and Talcite is blended in a proportion of 5 parts by weight or more to form the desired composition.

Of these essential ingredients, chlorine-containing polymany is
It is essentially a raw material for adhesives, and specifically,
Chlorosulfonated polyethylene, chlorinated natural rubber, chlorinated ethylene-propylene terpolymer, chlorinated polydichlorobutadiene, chlorinated polyvinyl chloride, copolymer of 2,3-dichlorobutadiene and d-chloroacrylonitrile, etc. I can do it.

In the present invention, depending on the chlorine content of the chlorine-containing polymer to be used, the chlorine-containing polymer is appropriately added so that the amount of chlorine is 5 to 35 parts by weight per 100 parts by weight of the solid content of the composition. The amount is adjusted. In addition,
If the amount of chlorine in the composition is less than 5 parts by weight based on 100 parts by weight of the solid content, the adhesive strength with non-polar rubber materials such as polyamide resins and EPDM will decrease significantly;
If the amount of chlorine exceeds 35 parts by weight per 100 parts by weight of the solid content, the heat resistance of the entire hose will decrease significantly. The amount is adjusted to 10 to 25 parts by weight.

Furthermore, polyisocyanate is added to such a composition in a proportion of 2 parts by weight or more based on 100 parts by weight of the solid content, which mainly improves the adhesion with the polyamide resin. It can be improved. Specific examples include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, etc. Diphenylmethane diisocyanate is particularly suitable, and it has been found that excellent effects can be obtained when added in an amount of about 5 parts by weight. Ta.

Furthermore, hydrotalcite, which is an essential component in such compositions, generally has the chemical formula: M g xA R2
It is a natural mineral represented by (OH)yCO:l ・ZH20, and in the above composition, its solid content is 100! By adding it at a ratio of 5 parts by weight or more to i parts, it is possible to significantly improve the heat resistance of the entire hose formed. According to the studies conducted by the present inventors, the optimum amount was about 100 parts by weight.

In addition, as long as the composition of the above essential ingredients is maintained, calcium carbonate, talc,
Various compounding agents such as a white filler such as silica, an acid acceptor such as a Pb0°MgO, P compound, carbon, and a vulcanizing agent may be added as appropriate.

As described above, the composition used as an adhesive in the present invention can effectively improve adhesiveness and heat resistance, and can effectively bond the inner tube layer 8 made of polyamide resin and the outer inner tube layer 8. While the tube layer 10 is well bonded, the heat resistance of the entire hose can be effectively improved. In particular, the outer inner tube layer 10 is made of EPDM, which has excellent heat resistance.
When using non-polar rubber such as, extremely high heat resistance can be obtained. It goes without saying that the characteristics of the polyamide resin used for the inner tube layer 8 provide excellent gas impermeability.

The materials for forming the outer tube layer 4 and the fiber reinforced layer 6 are appropriately selected from commonly used materials, and the outer tube layer 4 is made of EPDM.
, CR, etc., and the fiber reinforcing layer 6 is made by knitting yarns mainly made of synthetic fibers such as polyester fibers, legnon fibers, nylon fibers, aramid fibers, etc. by braid knitting, spiral knitting, etc. .

Incidentally, such a refrigerant transport hose according to the present invention can be manufactured by sequentially laminating the above-mentioned layers, for example, in the following manner.

(a) First, a polyamide resin, which is a material for forming the inner tube layer 8, is extruded from an extrusion molding machine onto a mandrel made of rubber or resin to form a tubular body. Then, the outer inner tube layer 10 is formed outside the inner inner tube layer 8 by repeating this extrusion operation or by co-extrusion molding, and at that time, between both layers 8 and 10, a composition according to the present invention is formed. An adhesive layer 12 is provided to form the inner tube layer 2.

0:I) Next, after applying an adhesive to the outer circumferential surface of the inner tube layer 2 as necessary, the fiber reinforced layer 6 is formed by braiding or spiral knitting the fiber reinforcing yarn.

(C) After applying a predetermined adhesive to the outer peripheral surface of the fiber reinforced layer 6, a rubber material for forming the outer tube layer is extruded to form the outer tube layer 4 to a predetermined thickness.

(C) After the thus obtained laminated tube is vulcanized (crosslinked) and bonded together, the desired hose can be obtained by removing the mandrel. The vulcanization conditions at that time are usually a temperature of about 140 to 170°C and a
A vulcanization time of about 0 to 90 minutes is set.

In the above description, a hose with a two-layer inner pipe layer has been described in detail, but it goes without saying that the inner pipe layer may have three or more layers. It is also possible to form a rubber layer on the inside of the tube layer 8 to improve nippleability with the joint. In that case, by applying the above-mentioned adhesive composition also between the innermost rubber layer and the inner inner tube layer 8 made of polyamide resin,
It is possible to improve the adhesion between these two layers, and it is also possible to increase the heat resistance of the two layers.

(Examples) Below, some examples of the present invention will be shown to clarify the present invention more specifically, but the present invention will not be limited in any way by the description of such examples. Needless to say, it is not something that can be accepted.

In addition to the following examples and the above-mentioned specific description, the present invention includes various changes, modifications, and changes based on the knowledge of those skilled in the art, as long as they do not depart from the spirit of the present invention. It should be understood that improvements and the like may be made.

First, solution-type adhesive compositions A to G were prepared according to the formulations shown in Table 1 below, using a mixed solvent of trichlorethylene and xylene as a solvent.

Next, as shown in FIG. 1, a total of seven hoses composed of the inner inner tube layer 8, the outer inner tube layer 10, the fiber reinforced layer 6, and the outer tube layer 4 were manufactured. Between layer 8 and outer inner tube layer 10, any of the adhesive compositions A-G was applied.

In addition, one hose was manufactured in which the inner tube layer 2 was composed of a single NBR layer. The specific inner tube layer configurations are shown in Table 2 below.

Then, for each hose, polyester fibers are knitted on the outer peripheral surface of the inner tube layer 2 by braiding (3
24 strokes), a fiber reinforced layer 6 is formed, and an outer tube layer 4 is further coated with EPDM on the outer peripheral surface of the fiber reinforced layer 6.
．． It was formed with a thickness of 4 mm. After that, a predetermined heating operation is performed to vulcanize the integral hoses (No. 1 to 1).
8) was obtained.

In addition, NBR and Cf-11R shown in Table 2
The compounding composition of each rubber material and the compounding composition of EPDM used for the outer tube layer are as follows.

Polymer (
AN=42%) 100FEF carbon black 60 dioctyl phthalate
10ZnO5 stearic acid 1 sulfur
1 Tetramethylthiuram disulfide 2N-cyclohexyl-2-benzothiazylsulfenamide 1 Formulation: LL dish) Do 1 (1-IIR polymer FEF carbon black paraffinic process oil nO Tetramethylthiuram disulfide stearate Luffy's former JS (For each of the hoses No. 1 to 8 obtained by was carried out in the following manner.

(1) A hose with an inner diameter of 11.5 mmφ was cut into 500 mm lengths, and 40 g of fluorocarbon gas (R12) was filled in the hose, and both ends of the hose were sealed.

After this was left at a temperature of 100° C. for 72 hours, the total weight was measured and compared with the initial weight to determine the number of grams of fluorocarbon gas permeated and evaluated.

The smaller the value, the better the gas impermeability.

(2) Hemostasis at 1 cram school) A hose with an inner diameter of 11.5 mmφ was cut into 500 lengths and heat aged at 150°C x 168 Hr in a gear type oven. Cuts were made as shown and 180°C bends were performed.

○: Good elasticity ×: Folding occurred (3) Test 1 A hose with an inner diameter of 11.5 mmφ was cut in the circumferential direction at a width of 1 inch, and the adhesiveness between the inner inner tube layer 8 and the outer inner tube layer 10 was checked. ,
It was examined by a 180 degree peel test in accordance with JIS-6301.

○: Good adhesion ×: Peeled off As is clear from the results in Table 2, the inner tube layer 2 is
It is clear that the hose (No. 1) made of a single layer of BR has extremely high gas permeability and poor heat aging resistance.

As shown in the test results for hose No. 2.3, depending on the amount of chlorine in the adhesive composition, if the amount of chlorine is too low, the adhesiveness will be significantly poor, and if the amount of chlorine is too high, As a result, heat aging properties are significantly inferior.

Furthermore, even if the adhesive composition has been adjusted in the amount of chlorine according to the present invention, when using adhesive composition C that does not contain polyisocyanate and hydrotalcite (
It is clear that hose No. 04) does not have sufficient effects in terms of both heat resistance and adhesion.

On the other hand, when using an adhesive composition in which the amount of chlorine is as specified and polyisocyanate is added in an amount according to the present invention (hose No. 5),
It has been observed that the adhesion of the hose is effectively improved and, in addition, when using an adhesive composition in which hydrotalcite is added in an amount according to the invention (hose N
116, 7.8), it can be seen that the heat resistance is also favorably improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a typical structure of a refrigerant transport hose according to the present invention, and FIG. 2 is an explanatory diagram showing a test method for the hose in an example. 2: Inner tube layer 4: Outer tube layer 6: Fiber reinforcement layer 8: Inner inner tube layer 10: Outer inner tube layer: Adhesive layer

Claims (1)

[Claims] It comprises an inner tube layer, an outer tube layer located outside the inner tube layer, and a fiber reinforcing layer interposed between both layers, and the inner tube layer is composed of at least two layers, an inner layer and an outer layer. , the inner layer of the hose is formed of a polyamide resin, and the amount of chlorine is 5 to 35 parts by weight per 100 parts by weight of solid content between the inner layer and the outer layer of the inner pipe layer. It has an adhesive layer made of a composition containing a chlorine-containing polymer in a proportion of 2 parts by weight or more, a polyisocyanate in a proportion of 2 parts by weight or more, and a hydrotalcite in a proportion of 5 parts by weight or more. A hose for transporting a refrigerant, characterized in that the inner layer and the outer layer are integrally bonded.