JP2002210749A - Vulcanizing method of rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate scatter of electric resistance of a vulcanized rubbery article, restrain generation of stickiness on the surface of the vulcanized rubbery article, enhance workability during vulcanization and reduce a production cost. SOLUTION: A vulcanizing method of a rubber comprises inputting an unvulcanized rubbery article (rubbery roller 1) in a vacuum pack 10 made of a deformable material the inner side of which is treated with a releasing agent, sealing an opening portion 11 of the vacuum pack 10 with a seal chuck 12, forming a vacuum in the vacuum pack 10 by vacuum suction, vulcanizing the unvulcanized rubbery article by pressing and heating it with the inner side of the vacuum pack 10 absorbed on the outer surface of the unvulcanized rubbery article, opening the seal chuck 12 after vulcanization to open the opening portion 11 of the vacuum pack 10 and taking out the vulcanized rubbery roller from the vacuum pack 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber vulcanization method, and more particularly, to improving the quality of a rubber product after vulcanization and improving workability and productivity during rubber vulcanization.

[0002]

2. Description of the Related Art Rubber compositions used for OA equipment such as electrostatic copying machines, laser printers, and facsimile machines, and rubber rollers for automatic teller machines are generally vulcanized. Conventional vulcanization methods include press vulcanization, Hot Water (hot water) vulcanization, inert gas environment vulcanization, and vacuum vulcanization, as described below.

[0003] Press vulcanization is a method of vulcanizing a compounded rubber placed in a mold while compressing (pressing) it between hot plates.
Rubber productivity is determined by the hot plate size of the vulcanizing press.
Therefore, in order to improve the productivity, it is conceivable to increase the size of the hot plate or to reduce the size of the hot plate and use a large number of hot plates. Since the processing of the mold is expensive, there is a problem that the manufacturing cost increases.

[0004] In addition, the rubber composition obtained by press vulcanization has a problem that the electrical resistance varies greatly.
In the product state of the rubber roller, it is required that the variation in the electrical characteristics is small (a common logarithmic value of electrical resistance logΩ <1), so that 2 <logΩ <3 and the variation in electrical resistance is large by the above press vulcanization. The obtained rubber composition becomes difficult to use as a product.

[0005] Hot Water (hot water) vulcanization is a type of can vulcanization method in which water is used as a heat transfer medium to vulcanize a rubber composition. However, since dissolved oxygen exists in water and this dissolved oxygen reacts with the rubber component,
There is a problem that stickiness occurs on the rubber surface after vulcanization, so that post-processing cannot be performed. Therefore, it is necessary to remove dissolved oxygen in the water. For this reason, the use of activated carbon or the like is indispensable, which leads to an increase in cost and a decrease in productivity.
Further, even if activated carbon is used, it is difficult to completely eliminate oxygen. Furthermore, a tank containing a large amount of water is required to secure productivity, and a heating time is required to raise the water temperature. In addition to this, there is a problem that the working efficiency is low because the evaporation of water cannot be avoided with pressurization and heating, and water needs to be added immediately before vulcanization.

[0006] Inert gas environment vulcanization is a type of can vulcanization method. In an industrial vulcanizer, air (oxygen) in the vulcanizer is replaced with an inert gas (nitrogen gas or the like). This is a vulcanization method. Although the reaction between the rubber component and oxygen in the air can be reduced, replacing the air with an inert gas requires work time, thereby lowering production efficiency and increasing the production cost due to the use of the inert gas. There is a problem.

[0007] On the other hand, vacuum vulcanization is a kind of can vulcanization method, but unlike general can vulcanization in which a medium is present, vacuum is applied to the inside of a container using a metal vacuum container to perform vulcanization. Due to the vulcanization, there is no medium at the time of vulcanization. Therefore, the vacuum container is in an oxygen-free state, oxygen does not react with the rubber component, and the rubber surface does not become sticky after vulcanization.
Therefore, as a method for vulcanizing rubber used for the rubber roller, vacuum vulcanization, which has many advantages overall, is suitably used.

[0008]

However, vacuum vulcanization using a metal vacuum vessel requires a large-sized vacuum vessel in order to secure productivity, and there is a problem that equipment is expensive. In addition, since the vacuum container is made of metal (metal can), the work of changing and handling the container corresponding to the size of the rubber roller to be vulcanized, the operation of removing the vulcanized product becomes complicated, and the production cost is increased. Is also high.

The present invention has been made in view of the above problems, and there is no variation in the electric resistance value of the rubber composition after vulcanization, no stickiness on the rubber surface after vulcanization, and no vulcanization. It is an object of the present invention to provide a rubber vulcanizing method which is excellent in workability at the time of vulcanization, reduced in equipment cost and excellent in productivity.

[0010]

In order to solve the above-mentioned problems, the present invention provides an unvulcanized rubber product placed in a vacuum pack made of a deformable material and subjected to an inner surface treatment with a mold release agent. The present invention provides a rubber vulcanization method characterized in that the inside of the vacuum pack is evacuated to a vacuum, and pressure and heat vulcanization is performed while the inner surface of the vacuum pack is adsorbed on the outer surface of the unvulcanized rubber product. .

As described above, vacuum vulcanization is performed using a vacuum pack made of a deformable material and having an inner surface treated with a release agent, with the inner surface of the vacuum pack adsorbed to the outer surface of the unvulcanized rubber product. Therefore, oxygen-free vulcanization can be easily performed without requiring large-scale equipment. Therefore, oxygen in the air and the rubber component do not react during vulcanization, and the occurrence of stickiness on the rubber surface after vulcanization can be suppressed. Also,
Compared to metal vacuum containers (metal cans), vacuum packs are made of deformable material, so they can be easily adapted to unvulcanized products and vacuum packs are easy to manufacture, so general-purpose High in nature. Further, since the vacuum pack is easy to handle, workability and productivity can be improved, and the cost can be reduced as compared with a vacuum container (metal can).

[0012] The inner surface of the vacuum pack is treated with a release agent. Thereby, the heat resistance, durability and strength of the vacuum pack can be improved. Also, even when vulcanizing with the inner surface of the vacuum pack adsorbed on the outer surface of the unvulcanized rubber product, the vacuum pack does not adhere to the rubber surface,
The product after vulcanization can be smoothly removed from the vacuum pack. The release agent is particularly preferably a fluororesin, and a silicone resin or the like is also suitably used.

The material of the vacuum pack is preferably an aluminum foil. When made of aluminum foil, heat resistance and durability are excellent, and a bag for a vacuum pack is easy to produce. Because of the foil shape, the shape is easily changed, it is easy to correspond to the shape of an unvulcanized rubber product, and versatility can be improved.

As a material of the vacuum pack, a heat-resistant resin having a heat-resistant temperature of 200 ° C. or more may be used in addition to the above-mentioned aluminum foil. Among them, a fluorine resin is preferable because of its excellent heat resistance.
Examples of the fluorine resin include polytetrafluoroethylene and polyvinylidene fluoride. Other than the fluororesin, a silicone resin or the like is also preferably used.

The vacuum pack is provided with a seal chuck mechanism for closing the opening of the vacuum pack, sealing the inside of the vacuum pack, and keeping the inside of the vacuum pack in a vacuum state.
Thereby, the operation of storing and removing the unvulcanized rubber product and the operation of vacuum suction can be facilitated.

The vacuum suction is preferably performed using a vacuum pump. After inserting a pipe of a vacuum pump for vacuum suction into the vacuum pack, it is preferable that the opening of the vacuum pack is closed with a seal chuck and vacuum suction is performed with a vacuum pump. This is preferable because the vacuum suction operation is easy and no large-scale equipment is required. The vacuum pump may be a small vacuum pump, as long as it can evacuate the inside of the vacuum pack.

The thickness of the aluminum foil used for the vacuum packing is 10
μm to 100 μm, preferably 20 μm to 50
μm or less. If the thickness of the aluminum foil is smaller than 10 μm, the durability and strength of the pack are reduced.
If it is larger than μm, it is difficult to handle unvulcanized rubber products having complicated shapes.

The thickness of the heat-resistant resin used for the vacuum pack and having a heat-resistant temperature of 200 ° C. or more is set to 10 μm or more and 100 μm or less. When the thickness of the fluororesin is smaller than 10 μm, the durability and strength of the pack are reduced. When the thickness of the fluororesin is larger than 100 μm, the uncured rubber product having a complicated shape is required. It is because there is a problem that it is difficult to respond.

The temperature at the time of vulcanization is preferably 100 to 200 ° C., more preferably 150 to 170 ° C. The above range is set when the temperature at the time of vulcanization is 100
If the temperature is lower than ℃, there is a problem that the vulcanization time becomes longer and the productivity is lowered, and if the temperature at the time of vulcanization is higher than 200 ° C, there is a problem that the durability of the pack is lowered and the performance of the vulcanized product is lowered. It depends.

The pressure at the time of vulcanization is 1.0 kgf / cm ² or more and 15.0 kgf / cm ² or less, and further 4.8 kgf / cm ^2.
It is preferable that the pressure be not less than cm ^{2 and not} more than 8.1 kgf / cm ² . From the relationship with the temperature, the pressure during vulcanization is preferably in the above range.

The vulcanization time is preferably from 10 minutes to 1 hour. The reason for setting the above range is that if the vulcanization time is shorter than the above range, the vulcanization is insufficient, and if the vulcanization time is longer than the above range, the performance of the vulcanized product is reduced and the productivity is deteriorated.

The outer surface of the vacuum pack is preferably subjected to heat and durability treatment. Specifically, it is preferable to be coated or laminated with a fluororesin.

The shape and size of the vacuum pack are such that the unvulcanized rubber product can be completely accommodated in the vacuum pack, and can be vacuum-sucked and can maintain a vacuum state in the vacuum pack. I just need. In addition, the vacuum pack
It can be used for vulcanization multiple times, not limited to multiple uses.

The unvulcanized rubber product may be any product that can be housed in a vacuum pack and vacuumed. In addition, one or a plurality of unvulcanized rubber products may be stored in one vacuum pack, and the vulcanization may be performed by storing the unvulcanized rubber products on a rack or a table.

As the rubber used for the unvulcanized rubber product, any rubber generally used is suitably used, but EPDM is optimal, and most preferably, EPDM is 100%. That is, EPDM has a main chain composed of a saturated hydrocarbon and does not contain a double bond in the main chain. For this reason, even if it is exposed to an environment such as a high-concentration ozone atmosphere or light irradiation for a long time, the molecular main chain is hardly broken. Therefore, the weather resistance of the rubber roller obtained after vulcanization can be improved. EP
Non-oil-extended EPD made of only rubber components
Oil-extended EPD containing confidential oil along with M and rubber components
M exists, but any type can be used.

In addition, butyl rubber, butadiene rubber (BR), isoprene rubber, styrene butadiene rubber (SBR), chloroprene rubber (CR), natural rubber (NR), acrylonitrile-butadiene rubber, acrylic rubber, ethylene propylene rubber are added to EPDM. One or two or more selected from EPM) may be blended. When EPDM and other rubber are mixed, EPDM in total rubber
Is preferably at least 50% by weight, more preferably at least 80% by weight.

As the vulcanizing agent to be added to the unvulcanized rubber product, sulfur, dicumyl peroxide and the like are preferably used.

Further, a vulcanization accelerator may be blended, and thiuram compounds, disulfide compounds and the like are preferably used.

The unvulcanized rubber products include, in addition to the above rubber components, resin components such as thermoplastic elastomers and olefin resins, oils, various fillers, and additives such as antioxidants. Needless to say, various components necessary for the above may be appropriately compounded.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. In the rubber vulcanization method of the present invention, first,
As shown in FIGS. 1A and 1B, a rubber roller 1 is used as an unvulcanized rubber product, and the rubber roller 1 is placed on a rack 2 and placed in a vacuum pack 10 made of aluminum foil. The vacuum pack 10 is deformable, and its inner surface 10a is subjected to an inner surface treatment with a release agent made of a fluororesin.
Next, as shown in FIGS. 1C and 1D, after inserting a pipe 20 of a vacuum pump (not shown) for vacuum suction into the vacuum pack 10, the opening 11 of the vacuum pack 10 is sealed. It is closed by the chuck 12, vacuum-evacuated by a small vacuum pump, and the inside of the vacuum pack 10 is evacuated. Then, the vacuum pump pipe 20 is pulled out from the vacuum pack 10 while vacuum suction is being performed.
Completely closes the vacuum pack 10. Further, FIG.
As shown in (E), the inside of the vacuum pack 10 is evacuated,
With the inner surface of the vacuum pack 10 adsorbed on the outer surface of the rubber roller 1, the vacuum pack is heated to 160 ° C. using a vulcanizing can.
Pressure and heat vulcanization is performed at a pressure of 5.5 kgf / cm ^{2 for} 30 minutes. After vulcanization, as shown in FIG. 1 (F), the seal chuck 12 is opened, the opening 11 of the vacuum pack 10 is opened,
The interior of the vacuum pack 10 is returned to normal pressure, and the vulcanized rubber roller 1 is taken out of the vacuum pack 10.

As shown in FIG. 2, the vacuum pack 10 is a rectangular bag made of aluminum foil having a length of 340 mm and a width of 500 mm, and extends over a length of 340 mm over a portion 30 mm from the short side end of the bag. A seal chuck 12 is provided, and the opening can be closed by the seal chuck 12. The thickness of the aluminum foil used for the vacuum pack 10 is 25 μm. Outer surface 1 of vacuum pack 10
0b is coated with a fluororesin as heat and durability treatment.

As shown in FIG. 3, the rubber roller 1 is an EPD.
It is formed from a rubber composition containing M as a main component, has a substantially cylindrical shape having a cylindrical hollow portion, and a cylindrical shaft 3 is press-fitted into the hollow portion or both are fixed by bonding with an adhesive. The length of the rubber roller 1 in the axial direction is 310 mm and the length of the shaft 3 is 330 mm.
The shaft 3 protrudes by 10 mm from a and 1b.
The outer diameter of the rubber roller 1 is φ14 mm, and the outer diameter of the shaft 3 is φ8 mm.

Thus, vacuum vulcanization can be easily performed without requiring large-scale equipment, and the occurrence of stickiness on the rubber surface after vulcanization can be suppressed. Further, since the vacuum pack is easy to handle, workability and productivity can be improved, and the cost can be reduced as compared with a conventional metal vacuum container (metal can).

In this embodiment, the material of the vacuum pack is made of aluminum foil. However, a deformable material having heat resistance such as a heat-resistant resin having a heat-resistant temperature of 200 ° C. or more may be used. Alternatively, a suction nozzle may be attached to the tip of the pipe of the vacuum pump, and then suction may be performed by the vacuum pump.

In this embodiment, one rubber roller is vulcanized. However, it is needless to say that an unvulcanized rubber product other than the rubber roller may be vulcanized. By changing the size of the vulcanized rubber product, it is possible to vulcanize an unvulcanized rubber product having a plurality or various shapes and sizes.

Hereinafter, Example 1 and Comparative Examples 1 to 3 of the rubber vulcanization method of the present invention will be described in detail. Example 1 and Comparative Examples 1 to 3 were each vulcanized under the respective conditions (temperature, pressure, vulcanization time) by the rubber vulcanization method shown in Table 1 below.

[0037]

[Table 1]

First, a rubber roller was produced as an unvulcanized rubber product. The rubber roller is used to put all materials such as rubber mainly composed of EPDM pelletized into a diameter of about 5 mm into a rubber kneading device such as a kneader, and knead it for about 15 minutes while heating it to 110 ° C. Extruded from the device. This was cut to the required length, and a shaft was fitted to produce it. The axial length of the rubber roller is 310 mm,
The length of the shaft was 330 mm, the outer diameter of the rubber roller was 14 mm, and the outer diameter of the shaft was 8 mm. The rubber rollers vulcanized in Examples and Comparative Examples were all manufactured under the same conditions as described above.

(Example 1) In place of the metal vacuum container (metal can) used in the conventional vacuum vulcanization, a vacuum pack made of aluminum foil was used. The rubber roller was vulcanized under the conditions described.

(Comparative Example 1) Ho, a kind of can vulcanization system
The rubber roller was vulcanized by tWater (hot water) vulcanization under the conditions shown in Table 1 using water as a heat transfer medium. Activated carbon was used to remove dissolved oxygen in the water. During vulcanization, 70 ° C. warm water was heated to 160 ° C.

(Comparative Example 2) Using a normal industrial vulcanizer,
Under the conditions described in Table 1, the rubber roller was can vulcanized. Vulcanization was performed in a state where air (oxygen) was present in the vulcanization can.

(Comparative Example 3) In the press vulcanization, the rubber roller placed in a mold was vulcanized while being compressed (pressed) between hot plates under the conditions shown in Table 1.

With respect to the rubber rollers vulcanized by the rubber vulcanization methods of Example 1 and Comparative Examples 1 to 3, respectively, the sticky rubber surface and the product
The variation of the volume-specific electric resistance value (electric resistance value) in the book was measured and evaluated. The results of each evaluation are shown in the lower part of Table 1 above.

(Method of Evaluating Stickiness of Rubber Surface) The surfaces of the rubber rollers obtained in the above Examples and Comparative Examples were evaluated by feeling when touched by hand. Three people touched the surface of the rubber roller with their hands, and all three did not feel sticky, and those with no stickiness were evaluated as "None" and those with even one felt sticky.

(Measurement of Volume Specific Electric Resistance) As shown in FIG. 4, the rubber roller 1 and the shaft 3 were used as electrodes, and after fixing the rubber roller 1 and the shaft 3, a voltage of 100 V was applied. In the axial direction of the rubber roller 1, the length of the rubber roller 1 was divided at equal intervals by 60 points, and the volume specific electric resistance value at each of the 60 points was measured in order. That is, instead of measuring the electric resistance in the circumferential direction, the electric resistance was measured in the axial direction. What is the variation in the volume specific electrical resistance value within one product after vulcanization?
It is the dispersion of the measured values at the above 60 points, which is 2.0 of 10
It is preferably a power of [Ω] or less. That is, the difference between the maximum value and the minimum value of the measured values at 60 points is preferably 100Ω or less. The resistance value variation of ^100.5 [Ω] means that the measured value is 100 ^. It shows that it varies in the range of ⁵ [Ω]. In Table 1, it is described as a common logarithmic value (logΩ) of the volume-specific electric resistance value.

Example 1 using a vacuum pack made of aluminum foil
In the rubber vulcanization method of (1), there is no stickiness on the rubber surface after vulcanization, the variation (logΩ) of the volume specific electrical resistance value within one rubber roller product is very small, 0.5 to 0.6, and The sulfurization time was as short as 0.5 hour (hrs), and it was confirmed that the productivity was excellent. In addition, it was confirmed that compared to the conventional vacuum vulcanization using a metal container (metal can), the cost was low and the workability was good because no large-scale equipment was used.

In the rubber vulcanization method of Comparative Example 1 using HotWater vulcanization, activated carbon is used, so that the rubber surface after vulcanization has no stickiness, and the variation of the volume specific electric resistance value in one rubber roller product. (LogΩ) is 0.7 ~
0.8 is small. However, it takes time to raise the temperature of hot water of 70 ° C. to 160 ° C., and the vulcanization time is 3.0 hours (h).
rs) and the number of steps such as addition of water increases,
Productivity and work efficiency were poor. As another method, a method of once raising the temperature of water to 100 ° C. or more, lowering the residual oxygen concentration in the water, and then charging the product and vulcanizing the product can be considered. And workability is poor, it takes time and productivity is low.

In the rubber vulcanization method of Comparative Example 2 by vulcanization using an industrial vulcanizer, the vulcanization time was 0.5 hour (hr).
s), and the variation (logΩ) of the volume specific electric resistance value within one rubber roller product is as small as 0.7 to 0.8, but oxygen in the vulcanizer reacts with the rubber component, and Stickiness occurred on the rubber surface.

In the rubber vulcanization method of Comparative Example 3 by press vulcanization, the rubber surface after vulcanization was not sticky and the vulcanization time was as short as 0.5 hour (hrs), but the volume in one rubber roller product was small. The variation (logΩ) of the specific electric resistance is 2.1
~ 2.6, which was unsuitable as a rubber roller product.

[0050]

As is clear from the above description, according to the present invention, since the vacuum vulcanization is performed using a vacuum pack made of a deformable material, the vacuum vulcanization is performed in a metal vacuum container (metal can). In comparison, it is easy to respond to the size of unvulcanized products, and it is also easy to manufacture a vacuum pack, so that the versatility for products to be vulcanized can be increased. In addition, vacuum packs are easy to handle, which improves workability and productivity, and does not require large-scale equipment, thus reducing costs compared to metal vacuum containers (metal cans). Can be.

Furthermore, since the inside surface is treated with a release agent and vacuum vulcanization is performed using a vacuum pack provided with a seal chuck mechanism, the product after vulcanization can be smoothly removed from the vacuum pack. And vulcanization can be performed efficiently.

As described above, without complicated oxygen removing work,
Vacuum vulcanization can be easily performed and the stickiness of the rubber surface after vulcanization is suppressed. Since it is possible to obtain a rubber composition having no variation in electric resistance value of the rubber composition after vulcanization, a rubber roller suitable for OA equipment such as an electrostatic copying machine, a laser printer, a facsimile, and an automatic deposit payment machine, etc. It can be provided at low cost.

[Brief description of the drawings]

FIGS. 1A to 1F are diagrams illustrating a rubber vulcanization method of the present invention.

FIG. 2 is a view showing a vacuum pack used in the rubber vulcanization method of the present invention.

FIG. 3 is a view showing a rubber roller used as an unvulcanized product in the rubber vulcanization method of the present invention.

FIG. 4 is a diagram showing a method of measuring a volume specific electric resistance value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rubber roller 10 Vacuum pack 11 Opening 12 Seal chuck 20 Pipe

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takayuki Tanaka 3-6-9, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo F-term in Sumitomo Rubber Industries, Ltd. 4F203 AJ02 AJ03 DA11 DB01 DC01 DD01 DF01 DL00 DL14

Claims (4)

[Claims] 1. An unvulcanized rubber product is placed in a vacuum pack made of a deformable material and subjected to an inner surface treatment with a release agent, and the inside of the vacuum pack is evacuated by vacuum suction. And vulcanizing under pressure and heat while the inner surface of the vacuum pack is adsorbed on the outer surface of the rubber. 2. The rubber vulcanization method according to claim 1, wherein the vacuum pack is formed from aluminum foil. 3. The rubber vulcanization method according to claim 1, wherein the vacuum pack is formed from a heat-resistant resin having a heat-resistant temperature of 200 ° C. or higher. 4. The vacuum pack according to claim 1, further comprising a seal chuck mechanism for closing an opening of the vacuum pack and maintaining a vacuum state in the vacuum pack. The rubber vulcanization method as described.