JPH10202670A - Method for vulcanizing and molding thick-walled unvulcanized rubber composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity of a vulcanizing and molding process to a large extent while holding performance of a thick-walled rubber product. SOLUTION: A thick-walled composite 10 formed by mutually bonding and integrating a plurality of kinds of unvulcanized rubbers is preheated by high frequency dielectric heating to be vulcanized and molded. In this case, a hydrous compd. is preliminarily added to and compounded with a component compsn. of unvulcanized rubber 10-1 low in a value of a loss factor represented by a product ε.tanδ of a specific dielectric constant (ε) and a dielectric loss angle (tanδ) among the unvulacnized rubbers and the range of a loss factor between the unvulcanized rubbers is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanized composite obtained by joining a plurality of types of unvulcanized rubber to one another by high-frequency dielectric heating, which is advantageously preheated for subsequent vulcanization molding. Regarding the molding method, in particular, the product ε · t of the relative dielectric constant ε and the dielectric loss angle tanδ between each unvulcanized rubber.
Suitable for thick composites with a difference in the value of the loss coefficient represented by an δ, the rubber product after vulcanization exhibits the expected sufficient performance, and at the same time, highly efficient vulcanization by high temperature and short time The present invention relates to a vulcanization molding method for a thick unvulcanized rubber composite, which enables molding and contributes to greatly improving productivity throughout the entire process.

[0002]

2. Description of the Related Art In a conventional general method of vulcanizing and molding a thick-walled composite solely based on heat conduction from its surface, an extremely small thermal conductivity unique to rubber is obtained from the surface to be heated to the inside. Because of this, the temperature rise is greatly delayed compared to the surface part, but as a rule, the vulcanization molding is carried out until this difficult temperature rise part reaches the appropriate degree of vulcanization (the degree of vulcanization that shows the most desirable physical properties that can be expected). Heating had to be continued.

[0003] In this case, the degree of vulcanization gradually increases from the hardly-heated portion to the surface portion, so that a portion closer to the surface portion shows a remarkably over-vulcanized state, resulting in deterioration of rubber properties and deterioration of product performance. In order to minimize this decrease in performance, vulcanization molding at a low temperature and for a long time is inevitable, resulting in a problem that productivity is significantly impaired. Have been.

[0004] The simplest means of this improvement is to reach a substantially uniform temperature throughout the thick-walled composite in a preheating chamber in which the ambient temperature is higher than room temperature but significantly lower than the vulcanization temperature. Heating method was adopted. However, in this method, if the set temperature for heating is too high, the vulcanization of the surface portion of the thick-walled composite body will proceed too much, so that it is necessary to keep the temperature low. It takes a long time to increase the temperature and the degree of heating is low, and it is inevitable that the productivity improvement throughout the vulcanization molding process will be insufficient, and in addition it will not solve the overvulcanization problem Was.

[0005]

Therefore, high-frequency dielectric heating, especially microwave heating, has been attempted as an even more effective method. However, even in this method, only in the case of a thick body having a single compounded rubber composition or in the case of a thick-walled composite, the compounded composition between the unvulcanized rubbers is similar only when the compounded composition between the unvulcanized rubbers is similar. By making the microwave electric field uniform, there is a disadvantage that rubber products that can be practically used are significantly limited, in that it is only possible to heat the hardly-heated portion to a desired temperature in a short time.

[0006] This point is, for example, a thick composite for solid tires suitable for use in forklifts and the like,
If each unvulcanized rubber is compounded and designed to meet different required properties, and there is a significant difference in the compounding composition between each unvulcanized rubber, microwave heating, especially excellent in heating efficiency, When heated, the temperature of the difficult-to-heat-up portion is substantially lower than that of the unvulcanized rubber having a high loss coefficient, for example, of the surface portion, which is inconvenient for the subsequent vulcanization molding. It is nothing less than causing

Japanese Patent Publication No. 57-42501 discloses a method of applying microwave heating to a tire before vulcanization molding, in which a tread rubber of a tire is subjected to microwave heating in advance, heated, and then assembled and molded. However, during the period from the assembly molding to the vulcanization molding, due to heat conduction to other joining members that are not subjected to preheating, the temperature is remarkably lowered particularly in the vicinity of the joining surface with the other joining members of the tread rubber, Further, if a plurality of rubber members are to be heated at the same time in order to avoid this, there is a great disadvantage in practical use, for example, a number of microwave heating devices corresponding to the number of members are required.

Therefore, high-frequency dielectric heating, particularly microwave heating, is applied to a thick-walled composite including unvulcanized rubbers having a composition that is significantly different from each other, so that the temperature of the difficult-to-heat-up portion of the thick-walled composite is increased. After raising the temperature to a desired temperature higher than the surface, vulcanization molding is performed to ensure that the product meets the required performance under the appropriate degree of vulcanization of the rubber over its entirety. It is an object of the present invention to provide a vulcanization molding method for a thick-walled unvulcanized rubber composite, which can exert its effects and greatly improve the productivity throughout the vulcanization molding process.

[0009]

A loss coefficient ε represented by a product of a relative dielectric constant ε of each unvulcanized rubber and a dielectric loss angle tan δ.
By focusing on tan δ, the inventors have found that the above object can be achieved, and have completed the present invention.

[0010] Previously, it has been found that the purpose can be achieved by adding conductive carbon black to unvulcanized rubber having a small loss coefficient (JP-A-6-344510). In some cases, the object of the present invention has been achieved by applying a hydrated compound exhibiting similar performance at lower cost in place of the conductive carbon black.

That is, (1) the vulcanization molding method of the thick unvulcanized rubber composite of the present invention comprises the steps of: forming a thick composite in which a plurality of types of unvulcanized rubbers are integrally joined together by high-frequency dielectric heating in advance. After heating and vulcanization molding, the relative dielectric constant (ε) and dielectric loss angle (tan δ) of each unvulcanized rubber
By adding a water-containing compound in advance to the component composition of the unvulcanized rubber having a small value of the loss coefficient represented by the product ε · tan δ of the unvulcanized rubber, to reduce the difference of the loss coefficient between the unvulcanized rubbers. It is characterized by.

(2) In the vulcanization molding method for a thick unvulcanized rubber composite according to the present invention, in the above item (1), the hydrated compound is a compound which releases water at 50 to 200 ° C. It is characterized by.

(3) The vulcanization molding method of the thick unvulcanized rubber composite according to the present invention is characterized in that, in the above (1), the amount of the water-containing compound is determined by adjusting the rubber content of the unvulcanized rubber to which the compound is added. It is characterized by being 0.5 to 20 parts by weight based on 100 parts by weight of the component.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings.

2 (a), 2 (b) and 3 (a),
(B) shows an annular thick composite 10 which becomes a solid tire after vulcanization molding as an example of a thick unvulcanized rubber composite, FIG. 2 shows two types of unvulcanized rubber, and FIG. The following shows an example in which unvulcanized rubbers are joined and integrated with each other. FIG. 2
(A) and FIG. 3 (a) are perspective views of the thick composite 10 and FIG.
(B) and FIG. 3 (b) are cross-sectional views taken along the line AA, respectively, and B in the figure represents a difficult temperature rising portion.

2 and 3, the annular thick composite 10
Is the innermost unvulcanized rubber 10-1 in the radial direction,
In the example shown in FIG. 3, an unvulcanized rubber having a compounding composition different from that of any of the rubbers is provided between the rubber and the outermost unvulcanized rubber 10-2 having a compounding composition greatly different from that of the rubber. The rubbers 10-3 are joined and integrated with each other.

Referring to FIG. 3 as an example, the thick composite 10
Are preheated by high-frequency dielectric heating, and prior to vulcanization molding, each unvulcanized rubber 10-1, 10-2, 10-
3, a predetermined hydrated compound is previously added to the component composition of the unvulcanized rubber having a small loss coefficient ε · tan δ, for example, the innermost unvulcanized rubber 10-1 and the intermediate unvulcanized rubber 10-3. And each unvulcanized rubber 10-
Reduce the loss factor difference between 1, 10-2 and 10-3.

The amount of the water-containing compound used in the present invention may be an amount within a range capable of maintaining the desired proper rubber physical properties in the solid tire product, and is preferably 100% by weight of the rubber component of the unvulcanized rubber to be added. 1.5 to
20 parts by weight, more preferably 5 to 15 parts by weight. The effect can be obtained with a small amount by adding a hydrated compound having a property capable of sufficiently contributing to the above-described reduction of the loss coefficient.

The hydrous compound used in the present invention includes:
Preferably, a compound that releases water at 50 to 200 ° C is included, and examples thereof include hydrated metal compounds such as hydrated sodium metasilicate, hydrated magnesium chloride, hydrated sodium pyrophosphate, hydrated sodium carbonate, and hydrated sodium sulfide. . Among them, hydrous sodium metasilicate and hydrous sodium pyrophosphate are preferable.

Thus, each unvulcanized rubber 10-1, 10-
The thickness of the thick-walled composite 10 is reduced beforehand by applying high-frequency heating to the thick-walled composite 10 after preliminarily reducing the range of the loss coefficient of 2, 10-3. After raising each part over the entire area to the desired temperature,
The vulcanization molding is performed. For preheating the thick unvulcanized rubber composite, microwave irradiation is preferable among high frequencies. Further, the degree of heating by the high frequency is actually determined according to the loss coefficient of the unvulcanized rubber as described later.

Although the above description has been given by taking as an example the thick composite 10 which becomes a solid tire by vulcanization molding, the present invention can also be applied to other thick rubber tires in general and other thick rubber composites in thick rubber articles. it can.

In general, the above thick-walled composite 10 is made of a plurality of types of unvulcanized rubbers 10-1 and 10-1 because a rubber product after vulcanization molding, for example, a tire needs to cope with different performance requirements.
Nos. 0-2 and 10-3 each have a significantly different blending design, so that the respective unvulcanized rubber compositions generally differ greatly from each other. Also, similar differences often arise in order to meet the demands of the manufacturing process.

Each unvulcanized rubber 10-1, 10-2, 10-
If the composition of No. 3 is greatly different, the value of the loss coefficient ε · tan δ in the high-frequency electric field also generally has a large difference between the unvulcanized rubbers. Therefore, when the thick composite body 10 in which these rubbers are joined and integrated with each other is heated by irradiating a high frequency wave, especially a microwave, the power loss of the microwave is not large because the value of the loss coefficient in the thick composite body 10 is large. As a result of being selectively concentrated on the vulcanized rubber portion, the unvulcanized rubber portion is mainly heated and exhibits a phenomenon in which the temperature becomes significantly higher than that of the other portions.

This is because the unvulcanized rubber 10-1, 10-2,
The microwave power loss P consumed at 10-3 is given by the following equation.

[0025]

## EQU1 ## P = (1 / 1.8) fv ² × ε · tan δ × 1
0 ^-10 (W / m ³ ) (where f represents the oscillation frequency (Hz) and v represents the magnitude of the electric field (V / m)) Here, in the right side of the above equation, the oscillation frequency f is It is reasonable to fix the thick composite 10 which is the object to be heated so as to be optimal.
If there is a large difference in the value of the loss coefficient between the unvulcanized rubbers, it is necessary to keep the loss coefficient within a predetermined limit in order to avoid the joy caused by an excessively heated portion. , 10-2, and the microwave power loss consumed at 10-3, that is, the amount of generated heat is a loss coefficient ε · ta
This is because it is proportional to nδ.

As described above, for example, each unvulcanized rubber 10-1 (for example, a loss coefficient of 0.2), 10-2 immediately after microwave heating is applied to the conventional thick composite 10
FIG. 4 shows an example in which the surface and internal temperatures of 10-3 (for example, a loss factor of 0.15) and 10-3 (for example, a loss factor of 0.1) are measured.
As shown in (a) (in the case of using two types of unvulcanized rubber) and (b) (in the case of using three types of unvulcanized rubber), the unvulcanized rubber 10-2 having the largest value of the loss coefficient was obtained. This is apparent from the fact that the internal temperature shows a remarkably higher temperature than the other unvulcanized rubbers 10-1 and 10-3.

Therefore, the object of the conventional microwave heating described at the beginning is a thick body having a single compound rubber composition or a similar material having a similar compound composition between unvulcanized rubbers. It is for the above reasons that it is limited to meat complexes.

Therefore, among the unvulcanized rubbers 10-1, 10-2, and 10-3 whose composition is greatly different from each other, the unvulcanized rubber composition having a small loss coefficient, for example, the unvulcanized rubber 1
By adding a predetermined amount of a hydrated compound having the above-described properties to 0-1, 10-3, the values of these loss coefficients can be increased.

This is because, as described in detail in the embodiments, the unvulcanized rubbers 10-1 (for example, loss coefficient 0.2) and 10-3 (for example, loss coefficient 0. 1)
By adding 1.5 to 20.0 parts by weight of the above-mentioned various water-containing compounds to 100 parts by weight of the rubber component of the unvulcanized rubber to be added, the values of these loss coefficients are both 1.00. It is the knowledge based on the result that it found that it increased.

Further, various types of the unvulcanized rubbers 10-1 and 10-3 having the above-mentioned loss coefficient value of 1.00 and the same unvulcanized rubber 10-2 (for example, a loss coefficient of 1.05) as the conventional example were used. The measured temperature immediately after high-frequency dielectric heating, for example, microwave heating is applied to the thick-walled composite 10 under the same irradiation conditions as the conventional example, will be described in detail with reference to FIGS. ) And FIG. 6 (which will be described in detail in the embodiment), but these are all low in the case where the difficult-to-heat-up portion B or its vicinity is particularly shown in FIGS. 4 (a) and 4 (b) of the conventional example. The temperature is lower than the surface,
This indicates that the temperature rises significantly until a higher temperature is indicated. FIGS. 4 to 6 show the cross section of the annular thick composite body 10 shown in FIGS. 2B and 3B divided vertically into two parts (w /
2) A temperature distribution graph in which temperatures measured at respective points on a line passing through the hardly-heated portion B are plotted.

Here, it is generally said that the penetration depth of microwaves into a dielectric material such as unvulcanized rubber having a single compounding composition is inversely proportional to the oscillation frequency f. Examples are shown in FIGS. 5 and 6. Such a heating phenomenon, for example, the shape of a thick body,
A microwave frequency f at which microwaves can be caused to overlap in the vicinity of the hardly-heated portion B depending on the size, rubber compounding composition, etc.
Is appropriately selected. In the examples shown in FIGS. 5 and 6, this frequency f was set to 915 MHz. Incidentally, when this frequency f was set to 2450 MHz, the result that the temperature of the difficult-to-heat-up portion B was significantly lower than that of the surface portion was shown. Was.

Further, by appropriately combining the above-described action with the amount or type of the hydrated compound added, it is possible to increase the temperature of the thick-walled complex 10 from the hardly-heated portion B of the complex 10 to the surface portion. The desired temperature distribution can be obtained.

Thus, the unvulcanized rubber 10 of the thick composite 10
-1, 10-2, and 10-3 reduce the difference between the loss coefficients, so that when the thick-walled composite 10 is subjected to high-frequency dielectric heating, particularly microwave heating, it is difficult to increase the temperature in the temperature rising portion B and its The temperature in the vicinity can be increased to a desired temperature, which is equal to or higher than the surface temperature.

In this case, the thick composite body 10 to be heated is
Depending on the composition, shape, dimensions, etc. of each unvulcanized rubber,
In addition to the optimum frequency f of the microwave, the output power or the magnitude v of the electric field around the object to be heated, various conditions such as the irradiation time are set, and the preheating is of course carried out. If the meat composite 10 is desirably subsequently subjected to vulcanization molding using a mold in accordance with a customary manner, a rubber product in which the degree of vulcanization at each part of the thick composite 10 is appropriately maintained in a short time at a high temperature can be obtained. .

As a result, the rubber product after vulcanization molding of the thick-walled composite 10 does not have excessive or insufficient vulcanization in each part thereof, and a small amount of a water-containing compound is enough to be added and compounded. Can be held. At the same time, high-efficiency vulcanization molding under high-temperature and short-time conditions becomes possible, which contributes to greatly improving the productivity throughout this process. Further, high-frequency output power such as microwaves can be further increased, and irradiation time can be shortened.

[0036]

EXAMPLES First, Examples 1 and 2 and Comparative Examples 1 and 2 to be described later.
An example of microwave heating common to the above will be described with reference to FIG.

FIG. 1 is a schematic structural view showing an apparatus for applying microwave heating to a thick-walled composite 10, which is a microwave generator 12, a microwave waveguide 14, and a thick-walled composite 1
An applicator 16 for applying microwave irradiation to a stirrer, and a stirrer (rotary blade) for reflecting and stirring microwaves in the applicator.
18, preferably a rotating support 20 made of a synthetic resin such as polypropylene that transmits microwaves. [Example 1, Comparative Example 1] The annular thick-walled composite 10 which becomes a solid tire after vulcanization molding has a total thickness t along the line AA of 10 cm according to FIGS. 2 (a) and 2 (b), The innermost unvulcanized rubber 10-1 is a rubber in which short fibers are evenly dispersed and mixed into ordinary rubber, the thickness t / 2 is 5 cm, the loss coefficient is 0.2, and the outermost unvulcanized rubber is 10%. Rubber 10-2 had the composition shown in Table 1, had a thickness t / 2 of 5 cm, and had a loss coefficient of 1.05. In this example, the difficult temperature rising portion is substantially at the center (w / 2) of the joining surface between the rubbers 10-1 and 10-2.
It was on the circumference B and the volume was about 17,500 cm ³ .

[0038]

[Table 1] Using the thick composite 10 described above as Comparative Example 1, the thick composite 10 of (A) and (B) in which the innermost unvulcanized rubber 10-1 was mixed with a hydrous compound according to the present invention described below, Each unvulcanized rubber 10-1 was provided with a suffix a or b, and prepared as Example 1. (A) 10-1a; 8 parts by weight of hydrous sodium metasilicate was added. (B) 10-1b; 10 parts by weight of hydrous sodium pyrophosphate was added. The loss coefficients of (A) and (B) were set to 1.00.

Each of Example 1 and Comparative Example 1 in (A) and (B) was separately subjected to microwave heating by the apparatus illustrated in FIG. The frequency f of the microwave is 915 MH
z, the output power was 3 KW, and the irradiation time was about 10 minutes.

After microwave heating, the temperature of each part of each thick-walled composite 10 was measured. Comparative Example 1 shows FIGS. 4 (a) and (A) and (B) of Example 1. 5 (a),
(B). 5A corresponds to FIG. 5A, and FIG. 5B corresponds to FIG. In each figure, the horizontal axis represents the thickness t (c).
m). As is clear from FIGS. 4A and 5, each thick composite body 10 of Example 1 has a higher temperature in the vicinity of the hardly-heated portion B than the surface portion, and has a preferable temperature distribution for the subsequent vulcanization molding. As shown, the temperature distribution of Comparative Example 1 was greatly improved.

Each of the thick-walled composites 10 was vulcanized and molded with a mold to obtain a solid tire, and the degree of vulcanization of each part of each solid tire was measured in the vicinity of the temperature measurement position in FIGS. Expressed as an index with the appropriate degree of vulcanization described as 100 at the beginning, Comparative Example 1 has a distribution in the range of 100 to 440, whereas (A) of Example 1
(B) falls within the range of 100 to 170, and there is no change in the basic physical properties of the rubber, and the product performance is secured.

In this connection, it was impossible to perform low-temperature vulcanization molding on Comparative Example 1 so as to fall within the range of the degree of vulcanization shown in each Example 1.

Example 2 and Comparative Example 2 Similarly, the thick composite 10 which is to be a solid tire has a total thickness t along the line AA of 10 cm according to FIGS. 3 (a) and 3 (b). The inner unvulcanized rubber 10-1 is a short fiber mixed rubber having the same loss coefficient of 0.2 as in Example 1, the thickness t / 2 is 5 cm, and the outermost unvulcanized rubber 10-2 is shown in Table 1. The loss coefficient of the same compound as in Example 1 is 1.05, the thickness is 2.5 cm of t / 4, and the intermediate unvulcanized rubber 10-3 has the compound composition shown in Table 1, and the loss coefficient is 0. .1, the thickness t / 4 is 2.5 cm
It is. Also in this example, the difficult temperature rising portion is located substantially on the center circumferential line B of the joining surface between the innermost unvulcanized rubber 10-1 and the intermediate unvulcanized rubber 10-3, and has a volume of about 17,500 cm ³ .

This thick-walled composite 10 was used as Comparative Example 2, and the innermost unvulcanized rubber 10-1 and the intermediate unvulcanized rubber 10 were used.
(C) obtained by adding and blending the following hydrated compound to -3 in Example 2.
Prepared as The suffix c is the same as in the first embodiment. (C) 10-1c; 8.0 parts by weight of hydrous sodium metasilicate was added.

10-3c: 1 part of hydrous sodium pyrophosphate
Add 0.0 parts by weight. The loss coefficient of each of the innermost and middle unvulcanized rubbers in (C) was set to 1.00.

Microwave heating was performed separately on the device of Example 2 and Comparative Example 2 in (C) using the apparatus illustrated in FIG. The microwave frequency f was 915 MHz, the output power was 3 KW, and the irradiation time was about 10 minutes.

After microwave heating, the results of successive measurements of the temperature of each part of each thick composite 10 are shown in FIG. 4 (b) for Comparative Example 2 and FIG. 6 for (C) in Example 2. The abscissa in the figure indicates the thickness t. As is clear from FIG. 4B and FIG. 6, also in the second embodiment, the thick composite body 10
The temperature in the vicinity is higher than the surface portion, and shows a favorable temperature distribution for the subsequent vulcanization molding, which is much more improved than the temperature distribution in Comparative Example 2.

Each of the above thick-walled composites 10 was also vulcanized and molded with a mold to obtain a solid tire, and then the degree of vulcanization of each part was measured near the temperature measurement position in FIGS. Is expressed by an index with the appropriate degree of vulcanization being 100, Comparative Example 2 also has a distribution in the range of 100 to 550, whereas (C) of Example 2 has a distribution of 100 to 18
0, and no change was found in the basic physical properties of the rubber, and the product performance was secured.

Further, it was not possible to attempt low-temperature vulcanization molding of the solid tire of Comparative Example 2 so as to fall within the range of the degree of vulcanization of each Example 2.

[0050]

According to the present invention, high-frequency dielectric heating, in particular, microwave heating is applied to a thick-walled composite containing an unvulcanized rubber having a composition greatly different from that of a plurality of types to make it difficult to raise the temperature. The pre-heating, which raises the temperature of the part to a higher temperature than that of the surface part, enables the product after vulcanization molding to have appropriate rubber physical properties that can sufficiently meet the required performance. Thus, it is possible to provide a vulcanization molding method for a thick-wall unvulcanized rubber composite, which can greatly improve productivity throughout the vulcanization molding step.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a microwave heating apparatus applied to the present invention.

FIGS. 2A and 2B show an example of a thick-walled composite, where FIG. 2A is a perspective view and FIG. 2B is a cross-sectional view taken along line AA of FIG.

FIGS. 3A and 3B show another example of a thick-walled composite, where FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view taken along line AA of FIG.

FIG. 4 is a diagram showing a temperature distribution of a conventional thick-walled composite by high-frequency dielectric heating.

FIG. 5 is a diagram showing a temperature distribution of high-frequency dielectric heating of the thick composite of Example 1 in the present invention.

FIG. 6 is a diagram showing a temperature distribution of a thick composite of Example 2 of the present invention by high-frequency dielectric heating.

[Explanation of symbols]

 Reference Signs List 10 thick-walled composite 10-1 unvulcanized rubber 10-2 unvulcanized rubber 10-3 unvulcanized rubber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3:24

Claims (3)

[Claims] 1. A thick-walled composite in which a plurality of types of unvulcanized rubbers are joined and integrated with each other, are heated in advance by high-frequency dielectric heating and then vulcanized. A water-containing compound is previously added to the component composition of the unvulcanized rubber having a small loss coefficient represented by the product of the ratio (ε) and the dielectric loss angle (tan δ). A vulcanization molding method for a thick-walled unvulcanized rubber composite, characterized in that the difference in loss coefficient between rubbers is reduced. 2. The vulcanization molding method for a thick unvulcanized rubber composite according to claim 1, wherein the water-containing compound is a compound that releases water at 50 to 200 ° C. 3. The amount of the water-containing compound added is 0.5 to 20 parts by weight based on 100 parts by weight of the rubber component of the unvulcanized rubber to which the compound is added. Vulcanization molding method of thick unvulcanized rubber composite.