JPH0976416A - Different kind compounded composition rubber article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a different kind compounded compsn. rubber article enhanced in the adhesive surface durability between adjacent rubbers having hardness difference of 5 deg. or more to a large extent without interposing other matter between the rubbers. SOLUTION: One rubber 2 of a different kind compounded compsn. rubber article 1 has a large number of banklike protruding parts 2P biting in the adhesive surface with one rubber 2 of the other rubber 3 of the article 1 and, in the cross section of the rubber article by the plane crossing the adhesive surface of the other rubber at a right angle so as to traverse the protruding parts 2P, the relation between the unit length (Ls) of the adhesive surface of the other rubber 3 and the total length (Lt) containing the length along the protruding parts 2P of one rubber 2 present in the unit length (Ls) as one containing at least one protruding part 2P satisfies Lt=(1.2-4.0)×Ls.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an integrated vulcanization molding of two or more kinds of rubbers having different compounding compositions, and a rubber having a JIS A hardness of 5 degrees or more between adjacent different rubbers after vulcanization. With regard to the article, in particular, mechanical fatigue is increased when a mechanical stimulus is repeatedly applied to a rubber composition of different composition having a large elastic modulus difference showing a strong positive correlation with the hardness difference between a harder rubber and a softer rubber. As a result, fracture nuclei are generated on the adhesive surface of both rubbers or in the vicinity thereof, and the conventional rubber articles, which grow and significantly impair the life, generate fracture nuclei under similar mechanical stimulation conditions. The present invention relates to a rubber article that can suppress its growth and realize a long life.

[0002]

2. Description of the Related Art As a means for achieving a long service life at or near the adhesive surface of a rubber article as described above, when the difference in hardness between rubbers of different composition rubbers adjacent to each other is relatively small, or when the rubber article is repeatedly added to the rubber article. If the degree of mechanical input applied is small and therefore the mechanical fatigue of both types of rubber adhesive surfaces is also small, a cross-linking agent is formed in advance in the unvulcanized stage to form co-crosslinks on at least one of the two types of rubber adhesive surfaces Alternatively, a method of applying a rubber cement containing a large amount of a cross-linking aid and then subjecting both seed rubbers to vulcanization molding to prevent failure of the adhesive surface is generally carried out.

Contrary to the above case, when the hardness difference between rubbers of different compounding composition is large, or the degree of mechanical input repeatedly applied to the adhesive surface of a rubber article is large, and therefore the degree of mechanical fatigue is large. As a means of extending life,
Failure prevention, in which an intermediate rubber layer having physical properties matching the input form is interposed between the two types of rubbers to be adhered to each other and the intermediate rubber layer plays a role of absorbing strain and / or relaxing stress The method is also widely practiced.

[0004]

However, the use of an organic solvent is unavoidable as a means for increasing the adhesive strength by rubber cement and preventing failure of the adhesive surface, which not only deteriorates the working environment but also uses fire. In addition to the need to give due consideration to restrictions and explosion-proof measures, when the usage conditions of rubber articles are wide-ranging, fatigue failure or initial failure will inevitably cause failure under severe usage conditions, so a satisfactory failure prevention method Not really.

Providing an intermediate rubber layer is a means that is not suitable for the current situation where the reduction of production cost as much as possible is strongly required because the productivity is remarkably reduced, and further, the desired performance or characteristics of the rubber article is realized. In some cases, it may be an obstacle to the operation, and in this case, the application of the intermediate rubber layer must be abandoned.

Therefore, an object of the present invention is to provide an extra member such as a rubber cement or an intermediate rubber layer on the mutual adhesive surface when different kinds of rubber having a hardness difference of 5 ° or more in terms of a compounding composition are integrated after vulcanization molding. It is an object of the present invention to provide a heterogeneous composition rubber article capable of exhibiting sufficient durability on the mutual adhesive surface or in the vicinity thereof even when the rubber article is used under severe use conditions without being interposed.

[0007]

In order to achieve the above-mentioned object, a rubber article of different compounding composition according to the present invention is the rubber article described at the beginning, in which one side rubber of different rubbers adjacent to each other is: The rubber on the other side has a large number of dam-shaped projections that bite into the adhesive surface with the rubber on one side, and the other side in a rubber article cross section by a plane that crosses the above-mentioned projections and is orthogonal to the adhesive surface on the other side rubber. The unit length (Ls) on the adhesive surface of the rubber, and the unit length (Ls) is the length along the convex portion of the rubber on one side existing in the unit length (Ls) that includes at least one convex portion. It is characterized in that the relation with the total length (Lt) including the height satisfies Lt = (1.2 to 4.0) × Ls.

In carrying out the present invention, preferably, the height of the convex portion measured from the above-mentioned adhesive surface is 0.2 to 2.0 mm and the width of the convex portion on the adhesive surface is 0.2 to 4.0 mm, respectively. When the length is within the range and the unit length (Ls) is 10 mm, two or more convex portions are present within this length.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiments shown in FIGS. FIG. 1 is a flat plate-shaped partial cross-sectional view (FIG. 1A) and a partially transparent plan view (FIG. 1B) of an endless or endless belt-shaped rubber article 1.

FIG. 1A shows a cross section taken along line X--X in FIG. 1B, and the rubber article 1 has two or more kinds (two kinds in the illustrated example) of different compounded composition rubbers (hereinafter simply referred to as rubbers). 2,
3 is integrated vulcanization molding, and after vulcanization between rubber 2 and 3 J
There is a difference of 5 degrees or more in the ISA hardness (hereinafter simply referred to as hardness), and it does not matter which rubber has the higher hardness in the illustrated example, but here, for convenience, the rubber 2 has a higher hardness than the rubber 3. Shall have.

The rubber 2 has a large number of dam-shaped projections 2p that bite into the bonding surface Sa with the rubber 3, and the cross-sectional shape of the projection 2p in the illustrated example is tapered. 1 is a plan view of the rubber 2 seen through the rubber 3 from the direction of arrow Z in FIG.
The example of the convex portion 2p shown in (b) extends straight on the adhesive surface Sa. The rubber article 1 determines whether the straight convex portions 2p are arranged in the rubber article 1 at regular intervals or at irregular intervals.
Any of them may be used depending on the configuration and the target durability, and a tilted arrangement may be used.

The section taken along line XX in FIG. 1B is a plane which is orthogonal to the bonding surface Sa and crosses the convex portion 2p, which is a plane which is also orthogonal to the linearly extending convex portion 2p. Point to. In this cross section, as shown in FIG. 1A, a unit length Ls is set on the bonding surface Sa of the rubber 3 within a range including at least one (two in the illustrated example) convex portion 2p. This actual setting is a length that passes through the bottom of the convex portion 2p of the rubber 2 shown by the chain double-dashed line in FIG.

At this time, the rubber 2 within the unit length Ls
Of the total length Lt = (1.2 to
It must be 4.0) × Ls. That is, the length Lt
Is in the range of 1.2 × Ls to 4.0 × Ls,
It is necessary to obtain the rubber article 1 in which the convex portion 2p is formed on the rubber 2 after vulcanization molding. In addition, the adhesive surface Sa is attached to the rubbers 2 and 3.
It is possible to reinforced organic fiber cords such as nylon and polyester, inorganic fiber cords such as glass and carbon and steel cords, and to embed reinforcing members in the parts except for, and so on.

FIG. 2 shows an annular rubber article 1 as another embodiment.
It is sectional drawing which passes along the width center of 0 part. The rubber article 10 is formed by integrally vulcanizing two or more (two in the illustrated example) different rubbers 12 and 13 as in the rubber article 1 described above, and the hardness between the rubbers 12 and 13 is 5 degrees or more. Similarly, it does not matter which rubber has a higher hardness in the illustrated example. In this example, the rubber 13 has a higher hardness than the rubber 12 for the sake of convenience.

The rubber 12 having a lower hardness is provided with a convex portion 12p similar to the teeth of a gear, so that the rubber 12 and the adhesive surface 13 are bonded to each other Sa.
The protruding portion 12p is made to bite into the rubber 13. The unit length Ls of the rubber 13 at this time is the length along the curved surface, that is, the length along the arc having the center of curvature O in the example of the cross section of FIG. 2, and the setting method of this length is as follows: The method for setting the total length Lt including the length along the portion 12p is the same as that for the rubber article 1. The length Lt is 1.2 × Ls-4.
It is the same that it is necessary to be within the range of 0 × Ls. The bonding surface Sa is not only cylindrical but also curved in the width direction (axial direction passing through the center of curvature O), and the projections 12p may be arranged in the width direction or in a tilted arrangement.

The dam-shaped convex portions 2p and 12p may have a rectangular cross-section, an arc-shaped cross-section, etc. in addition to the tapered cross-section, and the dam-shaped convex portions 2p and 12p.
In relation to the action direction of the principal strain or principal stress described below, even if it extends straight, it has a bent shape, it has a curved extending shape, and an array shape that alternates intermittently extends. The case where it is preferable to do so is included.

When a force acts on the rubber articles 1 and 10 having the above-mentioned convex portions 2p and 12p on the adhesive surface Sa, the adhesive surface Sa between the rubber 2 and the rubber 3 and the adhesive surface between the rubber 12 and the rubber 13 are adhered to each other. In addition to increasing the adhesive area between the Sas and improving the adhesive force, appropriate dispersion and relaxation of strain and / or stress on the adhesive surface Sa and its vicinity can be achieved. Especially, the convex portion 2 is formed in the direction orthogonal to the principal strain direction and the principal stress direction.
By arranging p and 12p, it is possible to obtain an effect that a rubber elastic modulus gradient is applied to the adhesive surface Sa, and this is effective for strain and / or stress as if the intermediate rubber layer were provided. Has a dispersion and relaxation effect. This was verified by the experiments described below.

The content of the experiment is that the ratio of the total length Lt having the convex portion 2p to the unit length Ls (called line ratio) Lt / L.
A test piece corresponding to a portion of the rubber article 1 was prepared by variously changing the value of s and the hardness difference between the rubbers 2 and 3, and the rubber article 1 was sufficiently fatigued by repeatedly applying a load to the test piece. After that, the rubber 2 and the rubber 3 are separated from the adhesive surface Sa.

The adhesive surface strength, that is, the adhesive surface durability, is evaluated by the appearance rate (%) of the peeled adhesive surface itself, and the appearance rate (%) is the adhesion when the unit length Ls is set. It is the percentage obtained by multiplying the value obtained by dividing the appearance area of the mutual adhesive interface between the rubber 2 and the rubber 3 on the surface by 100.
The evaluation of the durability of the adhesive surface is divided into five stages from A to E in order of appearance, and A: 0 to 10%, B: 11 to 20%, C: 21.
˜50%, D: 51-80%, E: 81-100%. When the appearance rate is less than 100%, it means that rubber is broken in the portion other than the adhesive surface, and therefore, the smaller the appearance rate value, the more excellent the adhesive surface durability. B here
From the practical point of view, the durability up to the stage, preferably the durability at the stage of B ⁺ : 11 to 15% is required. The experimental results are shown in FIG. 3 as a plot diagram using the symbols A to E themselves.

From FIG. 3, it can be seen that there is little difference in the compounding composition between rubbers having a hardness difference of less than 5 °, and a large adhesive force is easily obtained, and the strain and stress concentration on the adhesive surface are relatively gentle. From the above, it can be seen that sufficient durability is exhibited without providing a convex portion. Therefore, the hardness difference is 5
The present invention is applied to an integrated rubber article of the rubbers 2 and 3 having a degree of 0 ° or more. Further, when the hardness difference is 5 ° or more, when the line ratio value exceeds 1.0, more accurately, 1.2 or more, it is possible to obtain practically sufficient adhesive surface Sa durability, and the upper limit value of the line ratio is The hardness difference is 4.0 when viewed in the vicinity of 10 °. The above description is the same when the bonding surface Sa has a curved surface as shown in FIG.

Further, the height h of the protrusions 2p and 12p measured from the adhesive surface Sa is in the range of 0.2 to 2.0 mm,
Moreover, it is practically preferable that the width w of the bonding surface Sa is within the range of 0.2 to 2.0 mm. With respect to the height h and the width w, test pieces having various combinations of the height h and the width w were produced in the rubber article 1 of the rubber 2 and the rubber 3 having a hardness difference of 5 °. Similarly to the above experiment, the test piece was repeatedly subjected to mechanical fatigue, and this time, an experiment was conducted to evaluate the durability of the adhesive surface Sa by the peel strength. A test piece to which conventional rubber cement was applied was used as a control.

The peel strength is represented by an index with the control being 100, and the experimental results are shown in FIG. 4 as index values at positions corresponding to the width w and the height h. From FIG. 4, when both the width w and the height h of the convex portion 2p are less than 0.2 mm, there is not much difference from the case of rubber cement, and the upper limit values are the width w of 4 mm and the height h of 2 mm. I understand.

Further, the hardness difference between the rubber 2 and the rubber 3 is 20 °.
And the width w and height h of the convex portion 2p are each 0.2 m
m, a test piece having extremely disadvantageous conditions for securing practically sufficient durability is manufactured, and the peel strength is measured according to the above-mentioned experimental method, and the convex portion 2p is required per unit length of 10 mm. As a result of examining the number, it was found that the durability which is practically sufficient can be obtained by providing two or more convex portions 2p.

[0024]

EXAMPLES Using the rubbers having the three types of compounding compositions shown in Table 1, the endless belt 20 shown in FIGS. 5 (a) and 5 (b) was manufactured as the rubber articles of Examples 1 to 4 and Comparative Examples 1 to 7. did. This manufacturing method will be described later.

[0025]

[Table 1]

First, for the rubber 22 of the belt 20, the compound No. shown in Table 1 was used. The rubber of No. 3 was applied, and the unvulcanized member in which the nylon cord 24 was embedded in the longitudinal direction as a reinforcing member was prepared. Next, the rubber 23 attached to the surface side has a compound N
o. 1, No. The rubber of No. 2 is applied, and a sheet with a thickness of 3 mm is prepared by a roll at the unvulcanized rubber stage, and this sheet is preliminarily used for convex portions 2 under the condition of 80 ° C. for 30 minutes.
A semi-cured rubber having 3p was formed. Then, this semi-cured rubber was attached to a rubber 22 and vulcanized and molded to obtain an endless belt 20. Height h of the convex portion 23p
(Mm), width w (mm), and the number of convex portions 23p per standard length Ls of 10 mm are shown in Table 2. In addition, the CEM. Is rubber cement, and I.
L is the compounding number. Each of the two intermediate rubber layers (thickness 0.3 mm) is shown.

[0027]

[Table 2]

The endless belt 20 is shown in FIG.
It is mounted on the illustrated test machine and a durability test is performed.
Was. The test machine is a pair of drums R₁, R₂Equipped with
Ram R ₁Does not apply the rotational drive force after fixing the axial position.
Let's drum R₂Is free to rotate on the driven side and the pulling force T
It has a structure to operate.

The belt 20 mounted on these drums R ₁ and R ₂ has a compression pressure of 10 kgf / cm ² against the belt 20 due to the load applying drum R ₃ at the upper position of the driving drum R _1.
The load F is constantly applied. After the belt 20 was rotated for 72 hours at a speed of 300 m / min to fatigue the adhesive surface Sa, it was removed from the test machine to prepare a test sample, and a constant speed of 50 mm / min was set between the rubbers 22 and 23 of the sample. After peeling, the appearance of the adhesive surface was measured. The appearance was evaluated according to A to E according to the previous experiment. It should be noted that only the B level that is within the acceptance limit, and the durability level that can be satisfied even under severe use conditions is B ⁺ (appearance rate 11 to 1
5%), poor durability level ^B - (16 to 20%)
And subdivided. The test results are shown in the lower column of Table 2.

From the results of evaluation of the degree of appearance of the adhesive surface shown in Table 2, Examples 1 to 4 in which the hardness differences between different rubbers of the integrated rubber article 20 are 7 ° and 11 °, are rubber cement and intermediate rubber. It has been demonstrated that, without providing a layer, it exhibits excellent adhesive surface durability under repeated compressive loads. On the other hand, in Comparative Examples 1 and 2, although the hardness difference was 11 °, the dimension of the convex portion was improper, so that the durability was insufficient for practical use, and inclusions were not formed on the bonding surface. Side dishes, and Comparative Examples 4 and 7 which did not have a convex portion also similarly showed insufficient durability. Furthermore, in Comparative Example 3 in which rubber cement is applied, when the hardness difference is as large as 11 °, there is a gratification that it cannot exhibit satisfactory durability for use under severe test conditions.

[0031]

According to the present invention, an extra member such as a rubber cement or an intermediate rubber layer is formed on the mutual adhesion surface when different kinds of rubber having a hardness difference of 5 ° or more in terms of the compounding composition are integrated after vulcanization molding. Even if it is used under severe conditions where large strain and large stress are repeatedly applied without any interposition, it is as durable as or better than a rubber article with a conventional member interposed at or near the mutual adhesive surface. It is possible to provide a rubber article having a heterogeneous composition that can be exerted.

[Brief description of drawings]

FIG. 1 is a cross-sectional view and a perspective plan view of a band-shaped rubber article portion according to the present invention.

FIG. 2 is a cross-sectional view through the width center of the annular rubber article according to the present invention.

FIG. 3 is a scatter diagram showing the adhesion surface durability evaluation results of rubber articles after fatigue in relation to the difference in rubber hardness and the value of line ratio.

FIG. 4 is a scatter diagram showing the adhesion surface durability evaluation result of a rubber article after fatigue in relation to the width and height of a convex portion.

FIG. 5 is a side view of a main part of the evaluation device according to the embodiment of the present invention.

[Explanation of symbols]

1, 10, 20 Rubber articles 2, 12, 23 One side rubber 2p, 12p, 23p Convex part 3, 13, 22 Other side rubber Sa Adhesive surface Ls Unit length h Convex part height w Convex part width R ₁ rotation drive Drum R ₂ Tension drum R ₃ Loaded drum

Claims (2)

[Claims] 1. An integrated vulcanization molding of two or more rubbers having different compounding compositions, and vulcanization between adjacent different rubbers is performed.
In a rubber article having a difference in ISA hardness of 5 degrees or more, one side rubber of different types of rubbers adjacent to each other of the rubber article is a large number of dam-shaped projections that bite into an adhesive surface with the one side rubber of the other side rubber. And a unit length (Ls) at the adhesive surface of the other side rubber, and this unit length (Ls) in the rubber article cross section by a plane that crosses the convex portion and is orthogonal to the adhesive surface of the other side rubber. Has a relationship with the total length (Lt) including the length along the convex portion of the rubber on one side existing in the unit length (Ls) as including at least one convex portion, and Lt = (1.2 to 4.0) × Ls is satisfied, a rubber article of different compounding composition. 2. The height of the convex portion measured from the adhesive surface is 0.
2 to 2.0 mm and the width of the convex portion on the adhesive surface is 0.2 to
Within the range of 4.0 mm, the unit length (L
The rubber article according to claim 1, wherein when s) is 10 mm, there are two or more convex portions within this length.