JP7204184B2 - Vehicle door seal material - Google Patents

Description

The present invention relates to a vehicle door seal material. More specifically, it is installed along various vehicle doors and vehicle openings in the vehicle body, and has high sealing performance to prevent rainwater from entering the vehicle interior when the door is closed. It relates to a vehicle door seal material.

Conventionally, a vehicle door seal material (also referred to as a "vehicle weather strip") is attached along the periphery of a vehicle opening of a door as a movable member and/or a vehicle body as a fixed member ( For example, see Patent Document 1). For example, by closing a door on which a vehicle door seal material (hereinafter simply referred to as "seal material") is attached to the opening of the vehicle, the seal material is placed between the door and the vehicle body. is sandwiched. The sealing material may be attached to either one or both of the door side and the vehicle body side.

The sealing material is mainly made of a rubber material that is elastically deformable against stress. Therefore, when sandwiched between the door and the vehicle body, at least a portion thereof is crushed and deformed. At this time, a restoring force (repulsive force) acts on the sealing material to return it to its original shape where no stress is applied, so that a part of the surface of the crushed sealing material comes into close contact with the door or the vehicle body. As a result, water or the like is restricted from flowing between the vehicle exterior and the vehicle interior, and the interior of the vehicle is sealed by the sealing material.

This prevents insects and water such as high-pressure car wash water from entering the vehicle from the outside of the vehicle, the entry of fine contaminants such as dust and dirt other than water, or the noise, odor, or noise from the outside of the vehicle. Intrusion of wind or the like can be prevented. In other words, the sealing material does not make the driver and fellow passengers uncomfortable while driving, and a comfortable interior space can be maintained.

Furthermore, the sealing material can suppress the inflow and outflow of air both to the outside of the vehicle and to the inside of the vehicle. Therefore, it is possible to suppress the inflow and outflow of warm air or cold air from the inside of the vehicle to the outside of the vehicle (or from the outside of the vehicle to the inside of the vehicle). As a result, the vehicle interior temperature adjusted by the air conditioning device can be stably maintained. Therefore, it is possible to maintain excellent fuel efficiency, such as by suppressing the consumption of gasoline, etc., and to maintain high environmental performance.

As described above, the sealing material exhibits important functions in passenger cars and various other vehicles. Here, the basic structure of the sealing material will be described. The sealing material is a substantially plate-shaped seal base that is fixed to a door or a vehicle opening of a vehicle body via a known fixing means (for example, a clip or the like). and a seal portion of a hollow structure that is molded integrally with the seal base portion and partially crushed and deformed when the door is closed. A sealing material having a plate-shaped lip portion projecting in a predetermined direction from the seal outer surface of the seal portion is also formed.

As mentioned above, the sealing material is formed mainly from elastically deformable resin materials such as rubber materials, and is heated to a predetermined temperature to adjust the viscosity. It is formed into a desired shape using a well-known resin molding technique such as. Since the sealing material is elongated to be installed along the perimeter of the door, it is mainly formed by an extrusion technique. Here, as the rubber material (resin material) used as the main raw material, for example, ethylene-propylene-diene rubber (EPDM) or other thermoplastic elastomers are mainly used in many cases.

JP 2012-116451 A

As described above, the sealing material is one of useful members having high sealing properties such as a water stopping effect. Furthermore, it was possible to appropriately select the shape of the sealing portion and the resin material used as the raw material to exhibit higher sealing performance. However, if only high sealability is pursued, the following problems may occur.

That is, in order to obtain high sealing performance, it was necessary to press the seal portion with a strong force from one side (for example, the door side) toward the other side (for example, the vehicle body side) while the door was closed. . In other words, a high repulsive force (resilience) is required for the resin material forming the seal portion. In particular, in recent years, audio equipment such as high-performance speakers have been mounted inside vehicles, and more and more people are enjoying high-quality music in the vehicles. Therefore, in order to prevent the sound inside the vehicle from leaking to the outside of the vehicle, high sound insulation is sometimes required. As a result, a seal portion having a high repulsive force is often used.

Here, if the repulsive force is weak, there is a possibility that a gap will be formed between the sealing material and the vehicle body or the like that is in close contact, and there is a risk that water, dust, etc. will enter (or enter) through the gap. Therefore, a certain degree of repulsive force was required.

On the other hand, if the repulsive force is too strong, the force (energy) required to securely close the door may increase. That is, when trying to close the door, there is a possibility that the sealing material attached to the vehicle opening or the like weakens the force to close the door. For this reason, it has sometimes become necessary to perform a door closing operation in which the door is vigorously closed with respect to the vehicle body at a speed (door closing speed) higher than the regulation. As a result, elderly people and children with weak strength cannot close the door securely, resulting in a so-called "ajar door" state, or they have to repeat the operation of closing the door several times. As a result, drivers and the like may feel dissatisfied with the door closing performance.

In addition to the above-mentioned high sealing performance, in order to ensure good door closing performance, conventionally, the shape and thickness of the seal part have been changed, and the type of resin material itself has been changed. . Since sealing properties and door-closing properties contradict each other, it has been difficult to construct a sealing material that exhibits good properties for both.

The inventors of the present application, as a result of extensive research in order to solve the above problems, found that the rubber material (resin material), which is the main raw material of the sealing material, and the carbon component (carbon black) added to the rubber material are mixed. It was found that by adjusting the number of copies, a sealing material having both excellent sealing performance and door closing performance can be obtained. Furthermore, by focusing on the dynamic viscoelasticity, velocity dependence, and Mooney viscosity of the sealing material, and by defining each of these parameters within a predetermined range, a sealing material that is particularly improved in door closing performance can be stably obtained. It has been found that it is possible to form

Therefore, in view of the above-mentioned circumstances, the present invention provides a seal that maintains high sealing performance and has good door closing performance that allows the door to be securely closed even with a smaller force (energy) than conventional seals. The challenge is to provide materials.

According to the present invention, a door seal material (vehicle door seal material) that solves the above problems is provided.

[1] A vehicle door seal material containing a first component containing ethylene/propylene/diene rubber and a second component containing carbon black as raw materials, wherein the number of parts of the first component is equal to the number of parts of the second component. The value divided by 0. 83 to 1.25 , the Mooney viscosity is 25 to 61 ML (1+4) 125° C., the iodine adsorption of the carbon black is 20 to 40 mg/g, and the DBP oil absorption is 50 to 112 cm ³ /. Vehicle door seals in the range of 100 g .

[2] The vehicle door seal material according to [1], wherein the value of loss tangent indicating dynamic viscoelasticity is in the range of 0.095 to 0.210.

[3] Plot the results of the compression speed test with the horizontal axis as the compression speed [m / s] and the vertical axis as the load change rate [%], and the speed dependence [ %/(m/s)] value of 100 or less, the vehicle door seal material according to the above [1] or [2].

[ 4 ] The vehicle door seal material according to any one of [1] to [ 3 ], wherein the Mooney viscosity of the first component is in the range of 29 to 80ML(1+4)125°C.

[ 5 ] In addition to the first component and the second component, at least one of a softening agent, a processing aid, a filler, a cross-linking agent, a vulcanization accelerator, and a foaming agent is further included as a raw material in the above [1] The vehicle door seal material according to any one of to [ 4 ].

According to the sealing material of the present invention, it is possible to exhibit good door closing performance with a small force while ensuring high sealing performance similar to that of the conventional sealing material. As a result, even elderly people and children can securely close the door, and there is no need to repeatedly close the door when the door is ajar. As a result, inconvenience and dissatisfaction with the door closing operation can be eliminated.

FIG. 3 is a cross-sectional view showing the basic structure of the sealing material; It is a graph which shows an example of the test result of a compression speed test.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the sealing material (vehicle door sealing material) of this invention is described, referring drawings. The sealing material of the present invention is not limited to the following embodiments, and various design changes, modifications, improvements, etc. can be added without departing from the scope of the present invention.

1. Seal Material A seal material 1 according to an embodiment of the present invention is attached to a door (or vehicle body) of a vehicle such as a passenger car via a known means (not shown) such as a clip. For example, as shown in FIG. 1, the seal member 1 includes a substantially flat plate-shaped seal base portion 2 that contacts and is fixed to a door or the like, and a seal portion 3 that is integrally formed with the seal base portion 2 and has a hollow cross section. is mainly provided. Here, FIG. 1 shows a simplified configuration of the sealing material of the present invention, and is not limited to this cross-sectional shape.

When the vehicle main body or the like is approached while the seal base 2 is in contact with and fixed to a door or the like, the seal portion outer surface 4 of the seal portion 3 contacts a part of the vehicle main body, and the hollow seal portion 3 pushes. crushed and deformed. As a result, the hollow seal portion 3 is sandwiched between the door and the vehicle body in a deformed state, and the outer surface 4 of the seal portion is pressed against the vehicle body side by a repulsive force. As a result, the space between the vehicle body and the outer surface 4 of the seal portion 3 becomes tight, and high sealing performance such as water stoppage is ensured.

More specifically, the sealing member 1 is an elongated one obtained by extruding a resin material (rubber material) that is elastically deformable against stress. The sealing material 1 of the present embodiment uses ethylene-propylene-diene rubber (hereinafter referred to as "EPDM") as a main raw material as a resin material. Here, the component containing EPDM corresponds to the first component in the present invention.

Furthermore, the sealing material 1 of the present embodiment contains carbon black in addition to the first component. Here, carbon black corresponds to the second component in the present invention. That is, the above first component and second component are the main raw materials of the sealing material 1 of the present embodiment. Here, the resin component of the first component is not limited to the EPDM described above, and may be a rubber material composed of other synthetic resins, natural resins, or other known polymers such as thermoplastic elastomers. It may be a component. That is, it is sufficient that it elastically deforms against stress, has high sealing performance, satisfies the requirements to be described later, and has good door closing performance.

In addition to the raw materials of the first component containing EPDM and the second component containing carbon black, the sealing material 1 may contain various additives and the like. For example, at least one of a softening agent, a processing aid, a filler, a cross-linking agent, a vulcanization accelerator, a foaming agent, and the like may be added in an adjusted amount. The addition of these softening agents and the like is already well known in the production of sealing materials, so detailed description thereof will be omitted.

In the sealing material 1 of the present embodiment, the ratio of the number of parts to be blended between the first component and the second component is specified within the range shown below. That is, the value obtained by dividing the number of parts of the first component containing EPDM by the number of parts of the second component containing carbon black (hereinafter referred to as "first component/second component ratio") is 0.60 to It is characterized by being in the range of 2.00. By satisfying the condition that the value of the first component/second component ratio is within the above range, it is possible to obtain a sealing material with good door closing performance. Focusing on defining the first component/second component ratio within a predetermined range, it is a configuration unique to the present invention that it is possible to form a sealing material with good door closing performance.

Furthermore, according to the sealing material 1 of the present embodiment, the value of the loss tangent, which indicates the dynamic viscoelasticity of the rubber material, may be in the range of 0.095 to 0.210. Absent. By adjusting the value of the first component/second component ratio within the above range, the value of loss tangent (tan δ) relating to dynamic viscoelasticity of materials such as rubber materials can be within the above range.

"Dynamic viscoelasticity" is one of the properties of a rubber material or the like that greatly contributes to the door closing performance when the door is closed. A resin material such as a rubber material is a polymeric material in which a large number of single or multiple molecules are bonded. Polymeric materials generally exhibit “viscoelastic” properties, which are properties intermediate between “elastic” and “viscous” properties.

More specifically, "elasticity" has the property that "the force required for deformation is mainly determined by the magnitude of deformation and does not depend on the speed of deformation". is generally defined as having the property that "the force required for deformation is determined primarily by the rate of deformation and is independent of the magnitude of deformation". An ideal rubber is an example of an elastic body, and starch syrup is an example of a viscous body.

A value of loss tangent (tan δ) is sometimes used as an index for evaluating whether elastic properties or viscous properties strongly contribute to a resin material having properties as a viscoelastic body. . In general, the value (E″/E′≈tan δ) obtained by dividing the contribution of viscosity (E″) to the mechanical properties of a material such as a resin material by the contribution of elasticity (E′) is obtained as the loss tangent.

That is, the closer the value of the loss tangent to 0, the stronger the material has properties of an elastic body, while the larger the value of the loss tangent, the more the material has the properties of a viscous body. The sealing material of the present invention is characterized by having a loss tangent value within the range of 0.095 to 0.210, and has properties of both an elastic body and a viscous body.

When the loss tangent value is lower than 0.095, the property as an elastic body becomes strong, the value of the Mooney viscosity described later becomes low, and the processability deteriorates. On the other hand, when the loss tangent value exceeds 0.210, the property as a viscous body becomes strong. Therefore, by defining the value of the loss property within the above range, it is possible to form a sealing material that exhibits both high sealing performance and good door closing performance. The details of the measurement of the loss tangent value will be described later.

Furthermore, the sealing material 1 of the present embodiment is subjected to a compression speed test with the horizontal axis as the compression speed [m/s] and the vertical axis as the load change rate [%], and the test results are plotted and calculated. The value of velocity dependence [%/(m/s)] indicated by the slope of the approximation formula may be 100 or less. That is, the speed dependence is calculated based on the compression speed and the load change rate when pressure is applied to the sealing material 1 when closing the door, and the sealing material 1 with a value of 100 or less has good door closing performance. A specific example of the compression speed test will be detailed later.

Further, the sealing material 1 of the present embodiment may be characterized in that the Mooney viscosity of the sealing material 1 itself is in the range of 25 to 69ML(1+4)125°C. Here, the Mooney viscosity (M) is a unit for evaluating the plasticity of rubber materials, etc. After heating a sample to be evaluated at a predetermined temperature, It is calculated from the torque value obtained by obtaining the torque. In addition, the sample is heated at a predetermined heating temperature (for example, 125 ° C.), after preheating for 1 minute, the L-shaped rotor is rotated, and the value (Mooney value) after 4 minutes is "ML (1 + 4) 125 ° C." display as The details of the Mooney viscosity measurement will be described later.

In addition, the mooney viscosity of the first component, which is the raw material of the sealing material 1, may be in the range of 29 to 80ML (1+4) 125°C. Since the Mooney viscosity has already been explained, a detailed explanation is omitted here. This is because the Mooney viscosity of the first component greatly contributes to the overall Mooney viscosity of the sealing material 1 .

The sealing material of the present invention will be described below based on the following examples, but the manufacturing method of the present invention is not limited to these examples.

1. Preparation of sample (sealing material) The first component containing ethylene/propylene/diene rubber and the second component containing carbon black are mixed as the main raw materials, and the mixture is extruded into a long shape using a well-known extruder. A sealing material having a shape (see FIG. 1, etc.) was prepared.

As the EPDM contained in the first component, three types of ethylene-propylene-diene rubbers (EPDM1, EPDM2, and EPDM3) with different Mooney viscosities were used (see Table 1 below). EPDM3 is an oil-extended polymer, and resin component (EPDM): 100 phr, oil-extended: 20 phr was used. Therefore, for EPDM3, the ratio of the first component/second component, which will be described later, is calculated in consideration of the oil extension ratio. That is, the value obtained by multiplying the actual blending number X of EPDM3 by the oil extension rate Y is the blending number of EPDM3. Here, in the above example, the oil extension rate Y is resin component/(resin component + oil extension)=100/(100+20), which is approximately 0.83.

On the other hand, as the carbon black contained in the second component, three types of carbon black (CB1, CB2, CB3) having different particle sizes, iodine adsorption amounts, and DBP oil absorption amounts were used (see Table 2 below).

In addition to the above first and second components, other raw materials include paraffin oil as a softening agent, stearic acid and zinc oxide as processing aids, calcium carbonate as a filler, and sulfur as a cross-linking agent. In addition, a vulcanization accelerator, a foaming agent, and the like are added as appropriate.

As shown in Table 3 below, the sealing materials of Examples 1 to 7 and Comparative Examples 1 and 2 were obtained by changing the types of the first and second components used and the number of parts [phr] of each component. A stock was prepared prior to extrusion. In Examples 1 to 7 and Comparative Examples 1 and 2, the same number of softening agents, processing aids, etc. were used, except for changing the types and number of parts of the first and second components.

The raw material thus obtained was extruded into a desired shape using a well-known extruder to form a sealing material having a test shape as shown in FIG. The extruder and extrusion molding technique used are well-known ones used when forming existing sealing materials, and detailed description thereof is omitted here. Furthermore, other than the type and number of parts of the first component and the second component, various conditions such as the heating temperature and extrusion pressure of the raw material for extrusion were the same.

2. First Component/Second Component Ratio Values of the first component/second component ratio of the sealing materials of Examples 1 to 7 and Comparative Examples 1 and 2 formed by preparing the raw materials as described above are shown in Table 3 below. show. Here, as described above, since EPDM3 as the first component is an oil-extended polymer, the calculation is performed in consideration of the oil extension ratio. According to this, Examples 1 to 7 satisfy the first component / second component ratio range (0.60 to 2.00) specified in the present invention, and Comparative Example 1 is the first component / Those exceeding the upper limit of the second component ratio and Comparative Example 2 exceeded the lower limit of the first component/second component ratio, and both deviated from the first component/second component ratio specified in the present invention. be.

3. Evaluation of Seal Material As described above, the evaluation results of the seal materials of Examples 1 to 7 and Comparative Examples 1 and 2, which were formed in consideration of the first component/second component, are shown below.

3-1. Evaluation of loss tangent (dynamic viscoelasticity) The value of loss tangent (tan δ) was calculated in accordance with JIS K6394:2007 (vulcanized rubber and thermoplastic rubber-determination of dynamic properties-general guidelines). More specifically, Examples 1 to 7 and Comparative Example 1, which were prepared as described above, using a viscoelasticity measuring device RSA-3 (manufactured by TA INSTRUMENTS) as a measuring instrument for measuring viscoelasticity. A cylindrical test piece for measurement having a diameter of 6 mm and a height of about 2 to 3 mm was cut out from each of the sealing materials No. 2, set in a viscoelasticity measuring device, and measured.

In this case, the measurement conditions were uniform: number of tests: n=3, deformation method: compression method, static strain: 10%, dynamic strain: ±0.1%, measurement frequency: 1 Hz. The dynamic viscoelasticity was measured based on the measurement conditions, and the calculated loss tangent (tan δ) values are shown in Table 3 above. According to this, it was confirmed that all samples other than Comparative Examples 1 and 2 satisfied the loss tangent value condition (0.095 to 0.210) specified in the present invention.

On the other hand, it was confirmed that when the first component/second component ratio exceeded the upper limit of the specified range (Comparative Example 1), the value of the loss tangent decreased. That is, it was shown that when the ratio of the first component is large, the property as an elastic body is enhanced. On the other hand, it was confirmed that when the ratio of the first component to the second component was below the lower limit of the specified range (Comparative Example 2), the value of the loss tangent increased. That is, it was confirmed that when the ratio of the first component is small, the property as a viscous body becomes strong.

3-2. Compression Speed Test For the compression speed test, a 100 mm long sample was cut from the formed sealing material. After that, after fixing the load jig to the load cell, the load value is measured when the sample is compressed to the set reference position at a speed of 0.3 to 1.0 m / s, and the static load value (test speed: 20 mm/min) was calculated. After that, based on the calculated load change rate [%], a graph was created by plotting the compression speed [m/s] on the horizontal axis and the load change rate [%] on the vertical axis (Fig. 2).

An approximation formula showing the correlation between the compression speed and the load change rate was calculated from this, and the velocity dependence was evaluated by the gradient [%/(m/s)] of the obtained approximation formula. A well-known method can be used for obtaining an approximate expression from the plotted graph. For example, there are methods such as interpolating polynomials, least squares, Taylor series, Padé approximation, and continued fraction expansion. Any of these methods can be selected for determination. FIG. 2 shows a graph plotted for some examples and comparative examples among Examples 1 to 7 and Comparative Examples 1 and 2 for simplification of illustration.

In this embodiment, the slope of the approximate expression obtained from the graph is "A (=excellent)" when it is 40 or less, "B (=good)" when it is in the range of 41 to 70, and in the range of 71 to 100. Those with a value of 100 or more were evaluated as "C (=acceptable)", and those with a value of 100 or more were evaluated as "D (=impossible)" in the compression speed test. Table 3 shows the obtained speed dependency (≈the slope of the approximation formula) and the evaluation results thereof.

According to this, Example 4, which has a first component/second component ratio value of 1.25 and a loss tangent value of 0.097, which is the lowest among the examples, exhibits good speed dependence. It was confirmed that Furthermore, it was shown that the higher the value of the loss tangent, the lower the evaluation of the speed dependence. Although Comparative Example 1 obtained a favorable evaluation with respect to the speed dependence, the evaluation of workability, which will be described later, was low. In other words, even if only the speed dependence is considered to be good, the evaluation of the sealing material as a whole is low.

3-3. Workability (Mooney viscosity)
Furthermore, the Mooney viscosity ML(1+4) at 125° C. was measured to evaluate the workability of the sealing material. Mooney viscosity was measured in accordance with JIS K6300-1:2001 (Part 1: Method for determining viscosity and scorch time by Mooney viscometer). Specifically, using a Mooney viscometer (manufactured by M&K), after preheating for 1 minute using an L-shaped rotor at a temperature of 125 ° C., Mooney viscosity ML (1 + 4) when rotating the L-shaped rotor for 4 minutes 125°C was measured. The values of Mooney viscosity of the first component already explained are also determined under the same conditions as above (see Table 1).

The evaluation of the workability of the seal member is as follows: "B (= good)" when the value of the Mooney viscosity ML (1 + 4) 125 ° C. is in the range of 40 to 55, 25 to 39, or 56 to 70. Those within the range were evaluated as "C (=acceptable)", and those of 24 or less or 71 or more were evaluated as "D (=impossible)". The obtained Mooney viscosity values and evaluation results are shown in Table 3 above.

According to this, it was shown that Example 4, whose Mooney viscosity falls within the range of 40 to 55, has the best workability. However, a clear correlation with the first component/second component ratio, loss tangent, and speed dependence was not confirmed at this time.

3-4. Actual vehicle test evaluation Next, the sealing material of Example 4, which received the highest evaluation, was installed in an actual vehicle, and how much the door closing performance was improved compared to the existing sealing material used in the actual vehicle. was confirmed. Here, the actual vehicle test was conducted with a long sealing material attached to the periphery of the door on the front driver's seat side of the vehicle by a predetermined fixing means, and with all the doors and windows of the vehicle closed. That is, for the purpose of the test, an actual vehicle test was conducted under the conditions in which the inflow and outflow of air from the door other than the door for the door closing operation were suppressed, and the door closing performance was the worst.

Here, the door closing speed [m/s] was measured by attaching a reflector below the handle of the door and irradiating the reflector with a laser when closing the door. In other words, by closing the door, the speed of the door (reflector) is measured when it passes through the laser speedometer, and the door is completely closed. The speed was taken as the door closing speed in this embodiment. The results of the actual vehicle test evaluation are shown in Table 4 below.

According to this, the door closing speed measured by the existing sealing material is 0.95 [m/s], whereas the sealing material of the present invention has a door closing speed of 0.93 [m/s]. became. That is, the door can be reliably closed at a slower speed than the existing sealing material. Furthermore, it was shown that the energy per door was reduced by -4.2 [%]. As a result, even elderly people and children with weak arm strength can securely close the door. That is, it was shown that the sealing material of the present invention is effective in closing the door.

The sealing material (vehicle door sealing material) of the present invention can be attached to doors or vehicle body openings of various vehicles such as passenger cars, industrial vehicles, and agricultural vehicles, and is expected to be used in various other industrial technology fields. be done.

1: seal material (vehicle door seal material), 2: seal base, 3: seal portion, 4: outer surface of seal portion.

Claims (5)

A vehicle door seal material comprising a first component containing ethylene/propylene/diene rubber and a second component containing carbon black as raw materials,
The value obtained by dividing the number of parts of the first component by the number of parts of the second component is 0. in the range of 83 to 1.25 ,
Mooney viscosity is 25 to 61 ML (1 + 4) 125 ° C.,
The vehicle door seal material , wherein the carbon black has an iodine adsorption amount of 20 to 40 mg/g and a DBP oil absorption amount of 50 to 112 cm ³ /100 g . The value of loss tangent, which indicates dynamic viscoelasticity, is
The vehicle door seal material according to claim 1, which is in the range of 0.095 to 0.210. Plot the results of the compression speed test with the horizontal axis as the compression speed [m / s] and the vertical axis as the load change rate [%], and the speed dependence [% / ( m/s)] is 100 or less, the vehicle door seal material according to claim 1 or 2. The Mooney viscosity of the first component is
The vehicle door seal material according to any one of claims 1 to 3, which has a temperature range of 2 9 to 80 ML(1+4) 125°C. In addition to the first component and the second component,
The vehicle door seal material according to any one of claims 1 to 4 , further comprising at least one of a softening agent, a processing aid, a filler, a cross-linking agent, a vulcanization accelerator, and a foaming agent as a raw material.

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