JPH05194757A - Production of bonded rubber/rubber composite - Google Patents

Abstract

PURPOSE:To obtain a bonded rubber/rubber composite which is prevented from suffering ingredient diffusion or migration and having intact pliability by superposing two or more rubber materials having different specific compositions through the medium of polynorbornene rubber and thermally vulcanizing the rubber materials to unite and tenaciously bond them. CONSTITUTION:Two unvulcanized rubber materials consisting of different rubber compositions which contain the same kind of raw rubber having a critical surface tension, rc, of 26-36mN/m are superposed one on another through the medium of a polynorbornene rubber sheet or powder. The superposed materials are thermally vulcanized and united to thereby obtain a bonded rubber/rubber composite. The amount of the raw rubber in each composition is preferably at least 504 of the composition. The polynorbornene rubber is preferably one having a mol.wt. of one to five million. Mol.wts. exceeding one million serve to enhance the adhesion to the rubber materials and attain a higher bonding strength. If the mol.wt. exceeds five million, the polynorbornene rubber is difficult to produce and is less available commercially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rubber / rubber adhesive composite in which rubber materials composed of at least two kinds of rubber compositions containing the same or different raw rubber components are adhered to each other.

[0002]

2. Description of the Related Art Conventionally, rubber / rubber adhesive composites for tires, conveyor belts, hoses, lining products, etc. have been obtained by molding a plurality of types of rubber compositions into rubber materials and then laminating these unvulcanized rubber materials. It is manufactured by vulcanization and adhesion. However, when the above rubber materials are laminated, the compatibility between unvulcanized rubber materials is poor, or the vulcanization speed, cross-linking form, etc. are significantly different, and there is no so-called co-vulcanizability, so that they are strongly bonded. There is a problem that a bonded rubber / rubber bonded composite cannot be obtained. Moreover, the compounded chemicals contained in the rubber material diffuse and transfer to each other, and the vulcanization characteristics of the rubber material change, so that a rubber-rubber adhesive composite having good quality and performance cannot be obtained.

Further, when at least one of the rubber materials is vulcanized, the adhesion is very difficult. Even if an adhesive or the like is used as a countermeasure, it is difficult to sufficiently bond the adhesive, and the adhesive becomes hard, so that there is a drawback that the flexibility of the rubber-rubber bonded composite is impaired.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a rubber material composed of two or more kinds of rubber compositions is firmly adhered to each other regardless of the covulcanizability between them and whether or not the rubber material is vulcanized. At the same time, it prevents the diffusion and migration of the compounding components in the rubber material after adhesion, gives a number of useful properties, and does not impair the flexibility like an adhesive, and a method for producing a rubber-rubber adhesive composite. The purpose is to provide.

[0005]

In order to achieve such an object, in the method for producing a rubber-rubber adhesive composite of the present invention, a raw rubber contained in a rubber composition constituting the rubber-rubber adhesive composite. Different types of ingredients, vulcanization of rubber materials,
Intrinsic critical surface tension γc of unvulcanized and raw rubber components
According to the range of, it is divided into the following four modes. That is, in the first aspect of the present invention, the critical surface tension γc (hereinafter abbreviated as γc) is 26 to 36 millinewtons / meter (hereinafter mN).
(Abbreviated as “/ m”), rubber-rubber adhesion in which heat-vulcanization is integrated by interposing a polynorbornene rubber sheet or powder between unvulcanized rubber materials composed of two types of rubber compositions containing raw rubber components It is a manufacturing method of a composite. A second invention of the present invention is to provide a polynorbornene rubber sheet between rubber materials obtained by vulcanizing at least one of two kinds of rubber compositions containing the same kind of raw material rubber component having γ c of 31 to 35 mN / m. Alternatively, it is a method for producing a rubber-rubber adhesive composite body in which powder is interposed and heat vulcanization is integrated.

According to a third aspect of the present invention, γ c are both 31-31.
Heat-vulcanized and integrated by interposing a polynorbornene rubber sheet or powder between unvulcanized or vulcanized rubber materials composed of two kinds of rubber compositions containing different raw material rubber components of 35 mN / m. It is a method for producing a rubber-rubber bonded composite. Furthermore, in the fourth invention of the present invention, γ c is 2 on the one hand.
An unvulcanized rubber material composed of a rubber composition containing a raw rubber component of 5 to 31 mN / m, and a critical surface tension γc on the other hand.
A rubber which is heat-vulcanized and integrated by interposing a polynorbornene rubber sheet or powder between an unvulcanized or vulcanized rubber material composed of a rubber composition containing a raw rubber component of 31 to 35 mN / m. It is a method for producing a rubber-bonded composite.

As described above, according to the present invention, a polynorbornene rubber sheet or powder is interposed between a rubber material formed by molding a rubber composition containing the same or different raw rubber components having a specific γc, and heat vulcanization is performed. When integrated, the rubber materials can be adhered to each other regardless of their co-vulcanizability and whether they are vulcanized, and the norbornene rubber sheet or adhesive layer is used to spread the compounding components between the rubber materials. Since migration is prevented, fluctuations in the vulcanization characteristics of these rubber materials can be prevented. In addition, since the adhesive layer is thin and easily bent, the flexibility of the rubber-rubber adhesive composite is not impaired.

In the present invention, the critical surface tension γc is
August 20, 1978 (3rd edition), published by Maruzen Co., Ltd. "Chemical Handbook", Basic Edition II, page 618, as a family of liquid hydrocarbons and other organic liquid compounds on the solid surface. If the contact angle indicated by the row is θ and the surface tension of the liquid is γ, the relationship between cos θ and γ is almost a straight line regardless of the type of homologue. At this time, θ = 0, that is, cos θ
It is defined to mean the value of γc corresponding to = 1. However, the critical surface tension γc of the raw rubber component defined in the present invention
Is a value similarly measured using a rubber sample obtained by flattening the raw rubber component whose .gamma.c is to be measured by hot pressing, instead of the above solid.

The first aspect of the present invention is that γc is 26 to 36.
It is necessary to use two or more types of rubber compositions containing the same raw material rubber component in the range of mN / m. When the γc of the raw rubber component contained in this rubber composition is out of the above range, the polynorbornene rubber sheet or powder cannot firmly bond the rubber materials made of the rubber composition to each other. .. That is, the polynorbornene rubber has an excellent affinity for a rubber material containing a raw rubber component having a γc in the above range, and exhibits good adhesiveness.

As the raw material rubber component having γ c in the range of 26 to 36 mN / m, isobutylene-isoprene copolymer rubber (IIR, γc = 27 mN / m), ethylene-propylene-diene terpolymer rubber ( EPDM,
γc = 28 mN / m), natural rubber (NR, γc = 31 m
N / m), polybutadiene rubber (BR, γc = 32 mN
/ M), styrene-butadiene copolymer rubber (SBR,
γ c = 33 mN / m) and the like.

In addition to the above raw rubber component, a vulcanizing agent such as sulfur, a reinforcing agent such as carbon black, an antioxidant, a vulcanization accelerator,
A rubber composition having a predetermined composition is prepared by mixing other compounding agents. It is preferable that the raw rubber component is blended in the rubber composition at least 50% by weight or more. The obtained rubber composition is molded into a rubber material having an arbitrary stackable shape such as a sheet shape or a plate shape.
These rubber materials are metal cords such as steel cords,
It may be reinforced with a cord made of various organic fibers such as nylon, polyester and aramid.

Next, the rubber material produced by using the above-mentioned two or more kinds of rubber compositions is adhered using a polynorbornene rubber sheet or powder. The polynorbornene rubber used in the present invention is an amorphous glass transition point (Tg) 3 obtained from 2-norbornene represented by the following chemical formula 1.
It is a 5 ° polymer.

Chemical formula 1 The polynorbornene rubber is used as it is as a sheet or powder without compounding the above-mentioned compounding chemicals.
Further, the rubber may be an oil-extended rubber using a petroleum-based extender or an unoil-extended rubber. The molecular weight of the polynorbornene rubber is preferably in the range of 1,000,000 to 5,000,000. When the molecular weight is 1,000,000 or more, the adhesiveness and adhesive strength to the rubber material can be further increased. On the other hand, those having a molecular weight of more than 5,000,000 are not preferable because they are difficult to produce and industrially difficult to obtain.

When a polynorbornene rubber sheet is used, it preferably has a thickness in the range of 100 μm to 3 mm, which is sandwiched between the rubber materials to be bonded,
Heat to vulcanize and integrate. The thickness of this sheet is 100μ
By making it m or more, the adhesive strength can be increased,
On the other hand, the thickness of 3 mm or less ensures the flexibility of the bonded portion. When powder is used, the thickness of the adhesive layer should be about the same as the thickness of the above sheet,
After directly spraying on the adhesive surface of the rubber material or applying a mixture mixed with oil etc., it is heated and integrated by vulcanization.

The vulcanization adhesion conditions of the rubber material laminated by sandwiching the polynorbornene rubber sheet or the powder are preferably Tg of the polynorbornene rubber plus 50 ° C. or more and at a temperature at which the unvulcanized rubber material can be vulcanized. Is preferably pressed under heating. The lower limit of the heating temperature is preferably 130 ° C or higher in order to vulcanize the unvulcanized rubber material and obtain sufficient adhesive strength, and the upper limit is 240 ° C which is lower than the temperature at which the polynorbornene rubber or the rubber material is deteriorated. The following is desirable.

The second aspect of the present invention is that γ c is 31 to 35
In this method, two or more kinds of rubber compositions containing mN / m of the same raw material rubber component are used, and at least one of the rubber materials is vulcanized and used. However, the vulcanized rubber material used in the second invention has a γ c of 31 to 35 mN / m.
It is necessary to be composed of a rubber composition containing the raw rubber component of. This is because when the rubber material is vulcanized, a cross-linked structure is formed in the rubber, but the change in the molecular structure of the rubber due to this cross-linking substantially increases γc, and the polynorbornene rubber sheet or powder This is because the adhesiveness is reduced.
A second invention of the present invention is to obtain an excellent adhesiveness by increasing the affinity between the vulcanized rubber material and the polynorbornene rubber sheet or powder by making the upper limit of γc close to 35 mN / m. You can

This vulcanized rubber material is laminated with the above-mentioned unvulcanized rubber material or vulcanized rubber material, and then heated, and then vulcanized and bonded in the same manner as described above. Composites can be produced. Next, the third invention of the present invention is characterized in that the first invention of the present invention is provided between rubber materials composed of two kinds of rubber compositions containing different raw rubber components each having γ c of 31 to 35 mN / m. In the same manner as in (1), a polynorbornene rubber sheet or powder is interposed for fusion and integration. In the third aspect of the invention, it is necessary to use a rubber material composed of two or more kinds of rubber compositions each containing different raw material rubber components having .gamma.c of 31 to 35 mN / m. The combination of the rubber materials may be an unvulcanized material for both two types, a rubber material for which one of the two types is an unvulcanized rubber material and the other is vulcanized, or a rubber material for which both types are vulcanized. Examples of the raw rubber component having γ c in the above range include SBR and the like.

A fourth aspect of the present invention is a method for adhering a rubber material comprising a rubber composition containing raw rubber components having different γc ranges via a polynorbornene rubber sheet or powder. In the fourth invention, the rubber material on one side is composed of a rubber composition containing a raw rubber component having a γc of 25 to 31 mN / m, and is used in an unvulcanized state.
This is because a rubber composition containing a raw material rubber component having a large γc in the above range has an increased γc due to vulcanization, and the adhesiveness to the polynorbornene rubber sheet or powder decreases. The rubber material on the other side is 31-35 mN / m
And a rubber composition containing a raw rubber component having a small γc in the range of. The rubber material made of this rubber composition may be unvulcanized or vulcanized.

Similar to the first to third inventions, these two rubber materials are laminated through a polynorbornene rubber sheet or powder and then heated and fused to be integrated to produce a rubber-rubber adhesive composite. be able to.

[0020]

【Example】

Experimental Example 1 Five types of rubber compositions having the composition shown in Table 1 were prepared. As shown in Table 2, the rubber composition No. 1 (raw material rubber component NR), No. 2 (raw material rubber component EPDM) of Table 1
No. 3 (raw material rubber component SBR-NR) and No. 4 (raw material rubber component IIR) were each 150 mm x 50 mm x
It was molded into two 2.5 mm sheet-shaped rubber materials.

Two kinds of these rubber compositions, which are both unvulcanized, are laminated with a polynorbornene rubber sheet (having a molecular weight of about 3,000,000) having a thickness of 0.5 mm, respectively, and then laminated at 20 kg / A rubber / rubber adhesive composite was manufactured by heating at 160 ° C. for 20 minutes under a pressure of cm ² . The adhesiveness of the obtained rubber / rubber adhesive composite was evaluated by the following method, and the results are shown in Table 2.

[0022]

Further, * 1 is N-phenyl-N'-isopropyl-p-phenylenediamine * 2 is Nt-butyl-2-benzothiazolesulfenamide * 3 is tetramethylthiuram disulfide * 4 is 2-mercapto Benzothiazole * 5 is tetramethyl thiuram monosulfide * 6 is benzothiazyl disulphide. Adhesiveness evaluation method : Adhesiveness of rubber / rubber adhesive composite is
It is not accurate to evaluate the adhesive strength. Therefore,
A sample with a width of 20 mm was prepared and a peeling test was performed. If interfacial peeling occurred, even if the adhesive strength was high, it was defective.
It was evaluated as (x). On the other hand, if interfacial peeling did not occur, a sheet with a thickness of about 0.5 mm centered on the adhesive interface of the rubber-rubber adhesive composite was cut out with a razor, and scratches were made near the adhesive interface with a razor. Peel test 5
The adhesion was evaluated as good (∘) when one of the sheets was firmly bonded to cause cohesive failure inside.

[0024] From Table 2, in the case of the same unvulcanized rubber material, γc is 27.
It can be seen that all rubber materials using a general-purpose rubber having a hardness of up to 34 mN / m as a raw rubber component have good adhesiveness. Experimental Example 2 A rubber material was prepared using the rubber compositions Nos. 1 to 5 shown in Table 1. As shown in Table 3, one of the rubber materials was unvulcanized and the other was vulcanized. The same polynorbornene rubber sheet as that used in Experimental Example 1 was sandwiched between the rubber materials of the same type and the rubber material of the same type that was vulcanized for both types, and heated and fused and integrated. The adhesion of the obtained rubber / rubber adhesive composite was evaluated, and the results are shown in Table 3.

[0025]

From Table 3, the raw rubber component is IIR (γc =
In the case of the rubber composition of 27 mN / m) and EPDM (γc = 28 mN / m), if one of them is vulcanized, good adhesion cannot be obtained. On the other hand, γc of the raw rubber component is in the range of 31 to 35 mN / m, NR and SB
In the case of R-NR, it can be seen that even if one or both are vulcanized, both have good adhesiveness. Experimental Example 3 Rubber compositions No. 1 (NR) and No. 2 (EPDM) of Table 1
, No. 3 (SBR-NR) was used to produce a rubber material. As shown in Table 4, between two kinds of unvulcanized different rubber materials, one of two kinds is unvulcanized and the other is Between different kinds of vulcanized rubber materials, between different kinds of vulcanized different rubber materials,
The same polynorbornene rubber sheets as those used in Experimental Example 1 were sandwiched and heated to be fused and integrated. The adhesion of the obtained rubber / rubber adhesive composite was evaluated, and the results are shown in Table 4.
It was shown to.

[0027] As can be seen from Table 4, when two kinds of rubber materials made of a rubber composition containing different raw rubber components are bonded,
The adhesiveness differs depending on the γc of the raw rubber component and the vulcanization state of the rubber material. When the rubber material is made of a rubber composition containing a raw rubber component (NR, SBR) having a γ c within the range of 31 to 35 mN / m, the rubber material can be well bonded regardless of the vulcanized state. On the other hand, one of the two rubber materials is a raw rubber component outside the range of γc above.
When a rubber composition containing (EPDM) is used, good adhesion cannot be achieved when the rubber material is vulcanized. Experimental Example 4 Rubber compositions No. 2 (EPDM) and No. 3 (SBR in Table 1)
-NR) was used to prepare a rubber material, and as shown in Table 5, between two unvulcanized rubber materials, between one unvulcanized rubber material and the other vulcanized rubber material, The same polynorbornene rubber sheet as that used in Experimental Example 1 was sandwiched between the vulcanized rubber materials and the two materials, and the sheets were heated and fused and integrated. The adhesion of the obtained rubber-rubber adhesive composite was evaluated, and the results are shown in Table 5.

[0028] From Table 5, the raw rubber component with a small γ c value (EPDM = 2
8mN / m) and raw rubber component with large γc value (SBR =
In the case of a rubber material composed of a rubber composition containing different raw rubber components (33 mN / m), a rubber material composed of a rubber composition containing a raw rubber component (EPDM) having a small γc value is vulcanized. And a raw rubber component with a large γc value
It can be seen that a rubber material made of a rubber composition containing (SBR) cannot obtain good adhesiveness even if it is unvulcanized or vulcanized.

[0029]

As described above, according to the present invention, a polynorbornene rubber sheet or powder is provided between rubber materials made of a rubber composition containing the same or different raw rubber components having a specific critical surface tension γc. It is possible to manufacture a rubber-rubber bonded composite body in which the rubber materials are firmly bonded by interposing them and integrally vulcanizing them by heating. In addition, since the adhesive layer made of polynorbornene rubber can prevent diffusion migration of compounded chemicals between rubber materials after adhesion, vulcanization characteristics such as co-vulcanization properties of rubber materials and vulcanization conditions such as vulcanization temperature. Also, it can be bonded with or without vulcanization,
Moreover, the adhesive layer does not impair the flexibility of the rubber-rubber adhesive composite.

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Claims (4)

[Claims] 1. A polynorbornene rubber sheet or powder is provided between unvulcanized rubber materials composed of two kinds of rubber compositions containing the same raw material rubber component having a critical surface tension γ c of 26 to 36 millinewtons / meter. A method for producing a rubber-rubber bonded composite body in which heating and vulcanization are integrated by interposing a rubber. 2. A polynorbornene rubber is provided between rubber materials in which at least one of two kinds of rubber compositions containing the same kind of raw material rubber component having a critical surface tension γ c of 31 to 35 millinewtons / meter is vulcanized. A method for producing a rubber-rubber bonded composite body, in which a sheet or powder is interposed and heat vulcanization is integrated. 3. An unvulcanized or vulcanized rubber material composed of two kinds of rubber compositions containing different raw rubber components each having a critical surface tension γc of 31 to 35 millinewtons / meter. A method for producing a rubber-rubber bonded composite body, in which a norbornene rubber sheet or powder is interposed for heat vulcanization and integration. 4. An unvulcanized rubber material comprising a rubber composition containing a raw rubber component having a critical surface tension γc of 25 to 31 millinewtons / meter on the one hand, and a critical surface tension γc of 31 to 35 millinewtons on the other hand. Rubber / rubber bonded composite in which a polynorbornene rubber sheet or powder is interposed between unvulcanized or vulcanized rubber materials made of a rubber composition containing 1 / m of raw rubber component Manufacturing method.