JP5935208B2 - Cross-linked laminate of nitrile rubber and butyl rubber - Google Patents

Description

  The present invention relates to a rubber laminate in which a nitrile rubber layer and a butyl rubber layer are crosslinked and bonded, and a flexible hose using the rubber laminate.

  As a refrigerant transport hose for an automobile or the like, ones having structures disclosed in Patent Documents 1 and 2 are generally selected and used as appropriate.

  At present, eco-cars such as hybrid vehicles are equipped with an electric compressor as an air conditioner system. However, the lubricating oil is not a polyalkylene glycol (PAG) system conventionally used, but a polyol ester (POE). ) System is used. Here, in the hose in which the innermost layer disclosed in Patent Document 1 is made of a polyamide resin, there is no particular problem even if a POE-based lubricating oil is used, but the innermost layer disclosed in Patent Document 2 is a butyl rubber (hereinafter referred to as IIR). In the case of a hose comprising a POE-based lubricant, the compatibility between the POE-based lubricant and IIR is poor. Therefore, when the POE-based lubricant is used, the innermost layer IIR is likely to swell and cause a problem. However, the hose having the structure (inner pipe: rubber layer) disclosed in Patent Document 2 is very flexible and attached to the hose having the structure (inner pipe: resin layer + rubber layer) disclosed in Patent Document 1. The need for a hose whose inner tube is composed only of a rubber layer is still high because of its excellent workability.

  Therefore, by using a nitrile rubber (hereinafter referred to as “NBR”) that is highly resistant to POE oil and inexpensive, blending NBR with IIR, which is the innermost layer of the hose having the structure disclosed in Patent Document 2, prevents POE resistance. It is conceivable to improve oiliness or to provide NBR as a protective layer on the internal fluid side. However, when NBR is blended with IIR, it is difficult to maintain both the gas barrier property of IIR and the POE oil resistance of NBR. It is preferable to laminate with a layer.

  Here, as one of the bonding methods in the case of laminating these two independent layers, it is conceivable to bond the IIR layer and the NBR layer with an adhesive. In such a method, the bonding process using the adhesive is considered. And sufficient adhesive strength may not be obtained. Therefore, it is conceivable to crosslink and bond the IIR layer and the NBR layer, but the IIR and the NBR are greatly different in SP value (value indicating solubility), and the compatibility is very poor. In the past, there has been no technique for obtaining a rubber laminate by bonding. In order to solve such a problem, in Patent Document 3, in a laminate composed of two independent rubber compositions, the same rubber as that contained in one rubber composition is also contained in the other rubber composition. Then, the rubber layers having poor compatibility are bonded to each other by cross-linking.

Japanese Patent No. 3899718 Japanese Patent No. 3372475 JP 2007-98900 A

  However, in the technique as disclosed in Patent Document 3, characteristics of each rubber layer (for example, one rubber is oil resistant and the other rubber composition is mixed by mixing different types of rubber components in one and / or the other rubber composition. The rubber has a gas barrier property) which may be difficult to be exhibited or may be lowered.

  Accordingly, an object of the present invention is to provide a rubber laminate in which two rubber layers are crosslinked and bonded without using an adhesive and the characteristics of each rubber layer are maintained.

Rubber laminate of the present invention is a rubber laminate in which the NBR layer and IIR layer are laminated. Here, the NBR layer contains 2 parts by weight or more and 20 parts by weight or less of phenol resin and 1 part by weight or more and 20 parts by weight or less of epoxy resin with respect to 100 parts by weight of NBR. In addition, the NBR layer and the IIR layer are crosslinked and bonded with a phenol resin and an epoxy resin.

  According to the present invention, in order to cross-link the NBR layer and the IIR layer, the NBR layer contains a phenol resin and an epoxy resin. Thereby, since the favorable gas barrier property of an IIR layer can be maintained, maintaining the favorable oil resistance of an NBR layer, the characteristic of each rubber layer can be hold | maintained reliably. Moreover, the adhesiveness of a NBR layer and an IIR layer can be improved, without reducing the workability | operativity at the time of manufacture by making the mixture ratio of the phenol resin of a NBR layer and an epoxy resin into the said range.

  When the IIR layer also contains a phenol resin, the two rubber layers contain the same kind of cross-linking agent (phenol resin). It is possible to improve the adhesion.

  Further, when the NBR layer contains silica and 1,8-diazabicyclo [5,4,0] -7-undecene salt (hereinafter referred to as DBU salt), wetting at the interface between the NBR layer and the IIR layer Therefore, the adhesiveness between the two rubber layers can be further improved. Further, when the NBR layer contains 30 parts by weight or less of silica with respect to 100 parts by weight of NBR, the adhesiveness between the two rubber layers should be improved without deteriorating workability during the production of the NBR layer. Can do.

  Further, by using the rubber laminate as an inner tube material of the hose, it is possible to provide a flexible hose that maintains the characteristics of each rubber layer while the two rubber layers are firmly crosslinked and bonded without using an adhesive. it can.

  According to the rubber laminate of the present invention and the flexible hose using the rubber laminate, it is possible to provide a rubber laminate that retains the characteristics of each rubber layer while cross-linking and bonding the two rubber layers without using an adhesive.

(A) is a schematic diagram which shows the structure of the hose which concerns on embodiment of this invention, (b) is sectional drawing along the IB-IB line of Fig.1 (a). It is a flowchart explaining the manufacturing method of a hose. It is a flowchart explaining the modification of the manufacturing method of a hose.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Flexible hose 100]
As shown in FIG. 1, the flexible hose 100 is formed using a two-layer rubber laminate 10 in which an innermost NBR layer 1 and an IIR layer 2 are laminated in order, and a fiber is formed outside the IIR layer 2. A reinforcing layer 3 and an outermost rubber layer 4 are sequentially formed. The flexible hose 100 is used for a refrigerant transport hose such as an automobile.

(NBR layer)
The innermost NBR layer 1 contains NBR, a phenol resin, and an epoxy resin. The NBR layer 1 exhibits oil resistance by NBR which is a rubber component.

<NBR>
NBR contains acrylonitrile, and the oil resistance and low-temperature characteristics can be adjusted by the acrylonitrile content (AN amount). Specifically, if the amount of AN is too small, the oil resistance of the NBR layer 1 tends to decrease, and if the amount of AN is too large, the low-temperature characteristics tend to decrease. By adjusting, the balance between oil resistance and low temperature characteristics may be adjusted as appropriate. In addition, hydrogenated NBR may be used to improve heat resistance and the like.

<Phenolic resin>
The phenol resin is mainly used as a crosslinking agent for NBR, but is also used as a crosslinking agent for bonding the NBR layer 1 and the IIR layer 2 together. Examples of the phenol resin include a resol type phenol resin and a novolac type phenol resin.

<Epoxy resin>
The epoxy resin is a crosslinking aid and improves the adhesiveness at the interface between the NBR layer 1 and the IIR layer 2. Thereby, since the wettability between the NBR layer 1 and the IIR layer 2 is improved, the adhesion between the two rubber layers can be improved. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, cycloaliphatic epoxy resin, novolac epoxy resin, and the like.

  The NBR layer 1 of the present embodiment contains 2 parts by weight or more and 20 parts by weight or less of phenol resin and 1 part by weight or more and 20 parts by weight or less of epoxy resin with respect to 100 parts by weight of NBR. If the phenol resin content and the epoxy resin content are too large, when the material for the NBR layer 1 is manufactured, the material may become too sticky or bleed, resulting in a decrease in manufacturing workability. is there. On the other hand, if the phenol resin content and the epoxy resin content are too small, there is no problem in the manufacturing workability, but the adhesiveness between the NBR layer 1 and the IIR layer 2 cannot be sufficiently obtained. Therefore, by setting the content of the phenol resin and the content of the epoxy resin to the above blending ratio, it is possible to work without problems and improve the adhesion between the NBR layer 1 and the IIR layer 2.

  Here, the NBR layer 1 may further contain silica or DBU salt.

<Silica, DBU salt>
Since the wettability at the interface between the NBR layer 1 and the IIR layer 2 is further improved by the silica and the DBU salt, the adhesion between the NBR layer 1 and the IIR layer 2 can be further improved.

  Examples of the silica include crystalline silica, amorphous silica, wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid) and the like.

  Examples of the DBU salt include DBU-carbonate, DBU-stearate, DBU-2-ethylhexylate, DBU-benzoate, DBU-salicylate, DBU-hydroxy-2-naphthoate, DBU. -Phenol salt, DBU-2-mercaptobenzothiazole salt, DBU-mercaptobenzimidazole salt etc. are mentioned.

  The mixing ratio of silica and DBU salt is not particularly limited, but from the viewpoint of manufacturing workability of the NBR layer 1, it is preferable that 30 parts by weight or less of silica is contained with respect to 100 parts by weight of NBR. When there is too much silica content, when manufacturing the material for NBR layer 1, since the adhesiveness of a material becomes high too much, manufacturing workability | operativity may be reduced.

(IIR layer)
The IIR layer 2 contains IIR and a phenol resin. The IIR layer 2 exhibits gas barrier properties due to IIR which is a rubber component.

<IIR>
Examples of IIR include a copolymer of isobutylene and isoprene, and examples thereof include regular IIR and halogenated IIR (brominated IIR, chlorinated IIR, etc.). These rubbers may be used alone or in combination of two or more.

<Phenolic resin>
The phenol resin is mainly used as a crosslinking agent for IIR, but is also used as a crosslinking agent for bonding the NBR layer 1 and the IIR layer 2 together.

  Next, a method for manufacturing the flexible hose 100 will be described with reference to FIG.

(Adjustment and molding of NBR layer material)
A NBR layer material is prepared by adding a phenol resin and an epoxy resin to NBR and kneading them using a kneader or the like (S1). At this time, silica, DBU salt or the like may be added to NBR. Thereafter, the NBR layer material is molded into a predetermined shape to form a ribbon-shaped uncrosslinked NBR layer molded body (S2).

(Adjustment and molding of IIR layer material)
A IIR layer material is prepared by adding a phenol resin to IIR and kneading them using a kneader or the like (S3). Thereafter, the IIR layer material is molded into a predetermined shape to form a ribbon-like uncrosslinked IIR layer molded body (S4).

(Production of rubber laminate)
After forming the molded body for the NBR layer into a cylindrical shape for the hose by extrusion molding (S5A), the molded body for the IIR layer is molded into the cylindrical shape for the hose by extrusion molding and laminated on the outer periphery of the NBR layer (S5B). After that, the rubber laminate is crosslinked by heating (S6). After the extrusion (lamination) step (S5B), the fiber reinforcing layer 3 and the outermost rubber layer 4 may be formed on the outer periphery of the IIR layer.

  By heating (S6), the NBR layer 1 is manufactured by crosslinking the NBR layer molded body (NBR crosslinking), and the IIR layer 2 is manufactured by crosslinking the IIR layer molded body. (IIR cross-linking). Further, the NBR layer 1 and the IIR layer 2 are crosslinked and bonded by the phenol resin and the epoxy resin contained in the NBR layer 1 and the phenol resin contained in the IIR layer.

  As described above, in the present embodiment, since the NBR layer 1 and the IIR layer 2 are crosslinked and bonded in the heating process (S6) for manufacturing the NBR layer 1 and the IIR layer 2, a process for bonding the two layers is provided. It is not necessary. For example, when the NBR layer 1 and the IIR layer 2 are bonded by an adhesive, a step of bonding two layers separately from the heating step (S6) (for example, a step of applying an adhesive to each layer, two layers by an adhesive) In the present embodiment, the two rubber layers can be bonded without providing such a bonding process.

  Here, the phenol resin that cross-links and bonds the two rubber layers mainly acts as a cross-linking agent for NBR. Therefore, when the phenol resin is contained in the NBR layer, the characteristics of the NBR layer 1 may be maintained. it can. Further, since the phenol resin undergoes a crosslinking reaction with IIR, it also acts as a co-crosslinking agent for the interface between the NBR layer and the IIR layer. Furthermore, the epoxy resin provides NBR with excellent heat resistance and chemical resistance among various cross-linking aids, and also has stable adhesiveness on the rubber surface. Improves the wettability of the rubber layer interface. Further, when the epoxy resin is used together instead of using the phenol resin alone, these resins also react with each other, and thus contribute to the co-crosslinking reaction that occurs at the interface with the NBR layer 1 and the IIR layer 2. Therefore, in this embodiment, the oil resistance of the NBR layer 1 can be maintained, and the gas barrier property of the IIR layer 2 can be maintained. Therefore, when the flexible hose 100 of this embodiment is used as a refrigerant transport hose for an automobile or the like, the permeation of the refrigerant can be suppressed.

  As described above, according to the flexible hose 100 of this embodiment, since the NBR layer 1 contains the phenol resin and the epoxy resin, the NBR layer 1 and the IIR layer 2 are crosslinked and bonded by the phenol resin and the epoxy resin. To do. For this reason, two rubber layers can be firmly crosslinked and bonded without using an adhesive while maintaining good oil resistance of the NBR layer and good gas barrier properties of the IIR layer.

  In addition, the NBR layer 1 contains 2 parts by weight or more and 20 parts by weight or less of phenolic resin and 1 part by weight or more and 20 parts by weight or less of phenol resin with respect to 100 parts by weight of NBR. The adhesiveness between the NBR layer and the IIR layer can be improved without reducing the workability.

  Furthermore, the phenolic resin that crosslinks and bonds the two rubber layers mainly acts as a cross-linking agent for IIR. Therefore, among various cross-linking agents, it has an excellent balance of properties with respect to IIR, and is particularly heat resistant. Gives excellent characteristics. Therefore, when the phenol resin is contained in the IIR layer, the characteristics of the IIR layer 2 can be maintained.

  In addition, since the NBR layer 1 and the IIR layer 2 contain the same kind of cross-linking agent (phenolic resin), the two rubber layers easily cross-link and improve the adhesion between the two layers. Can be made. Furthermore, by including an epoxy resin in the NBR layer 1, the wettability of the interface is improved, so that the two rubber layers are easily cross-linked, and the adhesion between these two layers can be improved.

  Next, examples of the present invention will be described.

(Examples 1-11, Comparative Examples 1-10)
A test was conducted on the adhesion and manufacturing workability (roll workability and bleed resistance) of a rubber laminate having a two-layer structure of an NBR layer and an IIR layer.

  In this example and a comparative example, the test was performed by changing the blending material and blending ratio of the NBR layer. Table 1 shows the blending materials and blending ratio of the NBR layer, and Table 2 shows the blending materials and blending ratio of the IIR layer. Table 1 shows the test results (adhesiveness) of the rubber laminate and the test results of manufacturing workability (roll workability and bleed resistance).

Here, test conditions and test results will be described.
[Experimental conditions]
1. Preparation and molding of NBR layer material Add zinc oxide, stearic acid, FEF carbon, phenol resin, epoxy resin, silica and DBU salt to NBR (see Table 1) and knead them using a kneader and roll. Thus, the NBR layer material was prepared and formed into a sheet shape. Here, “-” in Table 1 indicates that the corresponding component is not added. Moreover, the “phenol resin” in Table 1 is a resol type phenol resin. Further, “Epoxy resin A” in Table 1 is a bisphenol A type epoxy resin, and “Epoxy resin F” is a bisphenol F type epoxy resin.
2. Preparation of IIR layer material and molding Addition of IIR to zinc oxide, stearic acid, FEF carbon, phenolic resin and silica (see Table 2), and kneading them using a kneader and a roll, IIR layer material Was adjusted and formed into a sheet shape. Here, the “phenol resin” in Table 2 is a resol type phenol resin.
3. Production of Rubber Laminate A two-layer rubber laminate was produced by laminating the sheet-like molded bodies obtained in 1 and 2 above and heating and crosslinking them.

Here, the following products were used for the above components.
・ NBR: Product made by Nippon Zeon (Product name) Nipol 1052J
-IIR: Made by JSR (Product name) JSR BUTYL 365
・ Zinc oxide: manufactured by Shodo Chemical Industry Co., Ltd. (product name): 3 types of zinc oxide ・ Stearic acid: manufactured by Shin Nihon Rikagaku Co., Ltd. (product name): stearic acid 50S
・ FEF carbon: Product made by Cabot Japan (Product name) Show Black N550
・ Sulfur: Made by Hosoi Chemical Co., Ltd. (Product name) Fine sulfur 500 mesh ・ TS: Made by Ouchi Shinsei Chemical Co., Ltd. (Product name) Noxeller TS (TS-P)
・ Peroxide: Product made from NOF (Product name) Perbutyl P (registered trademark)
・ Phenolic resin: Taoka Chemical Industries (Product name) Tactrol 250-I
-Epoxy resin A: manufactured by Mitsubishi Chemical (product name) jER 828
-Epoxy resin F: manufactured by Mitsubishi Chemical (product name) jER 806
・ Silica: Tokuyama (Product name) Tokuseal 233
-DBU salt: manufactured by Daiso (Product name) P-152

[Test results]
<Adhesive strength, peeled state>
A rubber laminate was formed into a test piece having a predetermined size, and a peel test (JIS K6256-1) was performed using the rubber laminate. Table 1 shows the “peeled state” of the two rubber layers as a result of the peel test. The “peeled state” indicates the degree of cross-linking adhesion at the rubber interface when the test piece is attached to a tensile test apparatus and one end of the NBR layer and one end of the IIR layer (one end on the same side) are pulled in opposite directions. ing. In Table 1, even when both layers are pulled, the two rubber layers do not peel at the interface, and one rubber layer is all destroyed, “◎”, and most, if not all, “○” Interfacial peeling did not occur, but when a part of the other rubber layer remained adhered to one rubber layer (when the other rubber layer was partially destroyed), it was designated as “Δ”. Further, “x” was given when interfacial peeling occurred.

<Roll workability>
In the adjustment of the NBR layer material, the roll workability when the material was kneaded using a roll was confirmed. When there was no problem in the roll operation, “◯” was given, when the NBR layer material showed tackiness, and when the adhesive component remained on the roll surface, “△”. Moreover, when the material for NBR layers showed adhesiveness and the material adhered to the roll surface and did not leave | separate from the roll surface, it was set as "x".

<Bleedability>
In the adjustment of the NBR layer material, the bleeding property by the epoxy resin when the material was kneaded using a roll was confirmed. When no bleed occurred, “◯” was given. When the bleed occurred but the amount of bleed was small, “Δ” was given, and when the amount of bleed was relatively large, “x” was given.

  From Tables 1 and 2, in Examples 1 to 11, the adhesiveness between the NBR layer and the IIR layer was good, and there was no problem in roll workability and bleeding property. Moreover, when Example 2 and Examples 6-10 using the same kind of phenol resin and epoxy resin are compared, although phenol resin and epoxy resin are the same content, Example 6 which added silica and DBU salt In the case of No. 10 to No. 10, adhesion was improved as compared with Example 2 in which silica and DBU salt were not added. Furthermore, Example 2 and Example 11 showed the same adhesiveness although the kind of epoxy resin used was different.

  On the other hand, in Comparative Examples 1 and 2, since another crosslinking agent was added to the NBR layer instead of the phenol resin and the epoxy resin, it is considered that the NBR layer and the IIR layer hardly adhered and interface peeling occurred.

  Moreover, in Comparative Example 3, since the phenol resin content and the epoxy resin content of the NBR layer were too small, it is considered that the adhesiveness was lower than in Examples 1-11.

  Further, in Comparative Examples 4 to 10, the production workability was lower than that of Examples 1 to 11 due to the difference in blending ratio with Examples 1 to 11. In Comparative Examples 4 and 5, since the phenol resin content and the epoxy resin content were too large, it is considered that roll workability and bleed resistance were lowered. Moreover, in Comparative Examples 6-9, since there was too much content of one of a phenol resin and an epoxy resin, it is thought that roll workability | operativity and / or bleeding resistance fell.

  Moreover, in Comparative Example 10, since the amount of silica added was large, the adhesiveness of the NBR layer material was increased, and it was considered that the roll workability was reduced.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments and examples, and various modifications are possible as long as they are described in the claims. .

  For example, in the present embodiment, the flexible hose 100 is formed using a two-layer rubber laminate, but may be formed using a rubber laminate including three or more layers of an NBR layer and an IIR layer.

  The fiber reinforcing layer 3 is formed of one layer of blade knitting, but may be formed of two layers of blade knitting or may be formed of a layer of spiral knitting. In these cases, a rubber layer may be further added between the fiber reinforcing layers.

  In the present embodiment and this example, the case where the NBR layer contains a phenol resin and an epoxy resin has been described, but both the NBR layer and the IIR layer may contain a phenol resin and an epoxy resin. . Further, the IIR layer may not contain a phenol resin.

  Furthermore, in this embodiment and this example, in the production of the flexible hose, as shown in FIG. 2, the NBR layer molded body and the IIR layer molded body are separately extruded (S5A, S5B) and laminated. However, as shown in FIG. 3, the NBR layer molded body and the IIR layer molded body may be simultaneously extruded and laminated (S5).

  Moreover, although this embodiment demonstrated the case where the rubber laminated body of an NBR layer and an IIR layer was used for refrigerant | coolant transport hoses, such as a motor vehicle, the use of the said laminated body is not restricted to the refrigerant | coolant transport hoses, such as a motor vehicle. It may also be used for packing and other hoses.

  Furthermore, the components contained in the NBR layer and the IIR layer are not limited to those shown in this embodiment and this example. Further, the NBR layer may not contain silica or DBU salt. In addition, in order to further improve the rubber properties and workability such as strength and ductility required for the hose, NBR is commercially available as a crosslinking agent such as a peroxide, an anti-aging agent, a plasticizer, a processing aid, and a coloring agent. You may add the compounding agent currently made as needed.

  By utilizing the present invention, the properties of each rubber layer can be maintained while the two rubber layers are crosslinked and bonded without using an adhesive.

1 NBR layer (nitrile rubber layer)
2 IIR layer (butyl rubber layer)
3 Fiber reinforcement layer 4 Rubber layer 10 Rubber laminate 100 Flexible hose

Claims (5)

A nitrile rubber layer and a butyl rubber layer are laminated ,
The nitrile rubber layer contains 2 parts by weight or more and 20 parts by weight or less of a phenol resin with respect to 100 parts by weight of nitrile rubber, and contains 1 part by weight or more and 20 parts by weight or less of an epoxy resin ,
A rubber laminate, wherein the nitrile rubber layer and the butyl rubber layer are crosslinked and bonded with a phenol resin and an epoxy resin .   The rubber laminate according to claim 1, wherein the butyl rubber layer contains a phenol resin.   3. The rubber laminate according to claim 1, wherein the nitrile rubber layer contains silica and 1,8-diazabicyclo [5,4,0] -7-undecene salt.   4. The rubber laminate according to claim 3, wherein the nitrile rubber layer contains 30 parts by weight or less of silica with respect to 100 parts by weight of nitrile rubber.   The flexible hose provided with the rubber laminated body of any one of Claims 1-4.