JP2005133741A - Method for manufacturing sponge rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely manufacture a sponge rubber roller of low cost, homogeneity, and low hardness, without irregularity in size and characteristics, in which fine cell diameter and thin cell film thickness can be stably achieved as desired without using vulcanizing molds. <P>SOLUTION: In conducting foaming vulcanization to an unvulcanized rubber roller after molding under heat and pressure by hot water, hot water temperature is set at 165°C, and pressure is increased up to 1470 kPa before the hot water temperature reaches the decomposition temperature of foam agent in the unvulcanized rubber roller. Before foaming vulcanization is completed, the pressure is reduced to 200kPa within 1min. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a sponge rubber roller that can be used as, for example, a charging roller, a developing roller, a static elimination roller, etc. for OA equipment, and proposes a technique that leads to a reduction in product cost and still a high product quality. It is.

In producing a low-hardness sponge rubber roller having a fine cell diameter, each unvulcanized rubber roller that has been molded is enclosed in a vulcanization mold and heated and pressurized in its foam molding cavity. Conventionally, foam vulcanization has been widely performed on unvulcanized rubber rollers.
According to this, the desired pressure can be applied to each unvulcanized rubber roller in the foam vulcanization process by the action of the vulcanization mold having the foam molding cavity. Since it can be heated to a temperature, a low hardness sponge rubber roller having a fine cell diameter and a thin cell wall can be produced.

  However, according to this conventional technique in which each unvulcanized rubber roller is foam vulcanized in a foam molding cavity, a vulcanization mold corresponding to the shape, dimensions, etc. of the sponge rubber roller as a product is required. In addition to the problem that the mold cost leads to an increase in product cost, it is also necessary to correct the mold for a design change of the product roller, which also contributes to an increase in product cost. was there.

  On the other hand, in terms of product quality, flash occurs on the peripheral surface of the roller at the part corresponding to the split position of the vulcanization mold, and unevenness in temperature distribution, pressure distribution, etc. occurs on the unvulcanized rubber roller in the foam molding cavity. If the uniformity of foam vulcanization is impaired, there is a problem that a uniform cell diameter and roller hardness may not be realized over the entire product roller, and the charging resistance of the product roller also becomes uneven.

  Therefore, in order to solve these product cost and quality problems, for example, a plurality of unvulcanized rubber rollers are arranged in a vulcanized can filled with pressurized steam, suspended and held, etc. Has been proposed to be foam vulcanized under the action of steam pressure and steam heat of pressurized steam.

  However, the general usage conditions of the conventional vulcanizing can are that the heating temperature is about 165 ° C., the pressure is about 784 kPa, and the pressure is insufficient for foam vulcanization of the sponge rubber roller. By foam vulcanization in the vulcanizing can, a sponge rubber roller having a sufficiently small cell diameter and a sufficiently small cell wall thickness could not be stably produced.

  On the other hand, when the vapor pressure of the vulcanization can is increased to about 1470 kPa, the pressure itself becomes a sufficient value, but this time the temperature will rise to a level exceeding 200 ° C. It was unsuitable for proper vulcanization.

  The object of the present invention is to solve such problems of the prior art, and the object of the present invention is to use a vulcanization mold that leads to an increase in product cost. A small cell diameter and a thin cell wall thickness can be stably provided, and there is no variation in their dimensions and various physical properties. It is in providing the manufacturing method of the sponge rubber roller which can be manufactured.

  The method for producing a sponge rubber roller according to the present invention includes foaming and vulcanizing one or more unvulcanized rubber rollers after molding, for example, in a vulcanizing can under direct heating and pressurization with hot water. The hot water temperature is set to a predetermined value within the range of 140 ° C. to 200 ° C., particularly 160 to 180 ° C., and the hot water temperature is the decomposition temperature of the foaming agent of the unvulcanized rubber roller, for example, Before reaching 100 to 140 ° C., the pressurizing force is increased to a predetermined set value of 980 kPa or more, in particular 1176 kPa or more, and then the pressurizing force is increased by 1 minute before the foam vulcanization of the rubber roller is completed. Within 500 kPa or less, more preferably 200 kPa or less.

  Here, the hot water can be heated to the required temperature, and of course, it can be pressurized to the required pressure without greatly affecting the temperature. By heating and pressurizing the unvulcanized rubber roller sufficiently evenly throughout, the unvulcanized rubber roller is foamed at an appropriate temperature and pressure without using a vulcanizing mold, and without unevenness thereof. This makes it possible to produce a sponge rubber roller having a fine and uniform cell diameter, a thin cell wall thickness, uniform dimensions and physical properties, etc. at a low cost. .

In this case, if the heating temperature is less than 140 ° C., the time required for foam vulcanization becomes long, and there is a possibility that a desired fine cell diameter cannot be obtained. There is a risk of vulcanization reversion.
If the set pressure is less than 980 kPa, as described above, it is difficult to make the foamed cell sufficiently fine, and it is difficult to make the cell wall thinner. It becomes difficult to stably manufacture the rubber roller.

  By the way, the pressurizing force in this case may be higher than the set pressurizing force due to its thermal expansion when heating water, warm water, etc. to a required temperature. In order to remove the pressure, it is preferable to provide the vulcanizing can with pressure adjusting means for absorbing the thermal expansion of water so that the internal pressure of the vulcanizing can can be controlled as expected.

  Here, the pressure is set to a predetermined set value before the hot water temperature reaches the decomposition temperature of the foaming agent of the unvulcanized rubber roller, for example, 100 to 140 ° C. This is preferable in order to increase the diameter and the certainty of realizing a uniform and thin cell wall thickness. Such a setting of the pressure can be performed after the start of vulcanization, but at the start of vulcanization. That is, at the same time as the start of vulcanization or prior to the start of the vulcanization, it is unnecessary to measure the pressure setting timing while considering the temperature rise rate of hot water. There are advantages.

  In addition, before the foam vulcanization of the unvulcanized rubber roller is completed, the pressure is rapidly reduced to a value of 500 kPa or less, more preferably 200 kPa or less within 1 minute, and the compressive force applied to the rubber roller is reduced. By rapidly and evenly reducing the entire cell, the cell diameter can be further miniaturized, the cell diameter can be made more uniform, and the cell wall can be further thinned. Further, the size and various physical properties of the sponge rubber roller can be made more uniform throughout, and the roller hardness can be advantageously reduced.

Here, the pressure is reduced to 500 kPa or less when the pressure exceeds 500 kPa, the pressure is still large, and the unvulcanized rubber roller is sufficiently foamed with the decomposition gas pressure of the foaming agent inside. Because it is not possible.
Further, if the decompression time is within 1 minute, if it exceeds 1 minute, the vulcanization proceeds non-uniformly in the decompression process, in other words, in the foaming process of the rubber roller, and the uniformity of the foamed cell is reduced. This is because the average cell diameter increases.

By the way, the timing of the decompression start before the completion of foam vulcanization will vary depending on the blending composition of the unvulcanized rubber roller. It is desirable to carry out at a moderate degree of vulcanization before complete completion.
In other words, when the degree of vulcanization is too low, the strength of the rubber is low, and the foaming agent decomposition gas escapes, so that the roller does not sufficiently foam or expand. Conversely, when the vulcanization proceeds too much, the strength of the rubber is too high to foam.

And preferably, the foamed cell diameter after completion of foam vulcanization is 100 μm or less, and the thickness of the cell wall is 50 μm or less.
According to this, it is possible to obtain a sponge rubber roll which is soft at a low density and uniform throughout.
That is, if the cell diameter exceeds 100 μm, unevenness in hardness, unevenness in dimensions, etc. are likely to occur, and if the cell wall thickness exceeds 50 μm, the roller hardness tends to increase.

  Thus, according to the present invention, in particular, before the hot water temperature in the vulcanized can reaches the decomposition temperature of the foaming agent of the unvulcanized rubber roller, the hot water pressure is increased to a predetermined set pressure, Prior to completion of foam vulcanization of the rubber roller, a combination of a pressure reduction to a value of 500 kPa or less within 1 minute, combined with a sponge as a product, compared to the case where only the above pressure setting is performed. The foam cell diameter of the rubber roller can be further refined, the cell diameter can be made more uniform throughout the roller, and the cell wall can be made thinner, so the dimensions and physical properties of the sponge rubber roller can be reduced. It can be made sufficiently uniform throughout, and at the same time, its hardness can be further reduced.

Embodiments of the present invention will be described below based on the drawings.
FIG. 1 is a schematic diagram illustrating a vulcanizing can used in the practice of the present invention. The vulcanizing can 1 as a pressure vessel includes a barrel portion 2 having a substantially cylindrical shape, and openings at both ends of the barrel portion 2. For example, as shown in the front view of FIG. 1 (b), the end plates 3 are hermetically sealed. It is provided with heating means 4 that can heat, for example, electric heating means, steam heating means, etc., to heat the water, hot water, etc., filled in the can at a required pressure to a required temperature.
In addition, this heating means 4 can also be turned up in each edge part of the trunk | drum 2, and can also be made to extend zigzag over the perimeter.

When foaming and vulcanizing the unvulcanized rubber roller after molding using such a vulcanized can 1, it is arranged in a matrix form as shown in FIG. 2, for example, in the body portion 2 of the vulcanized can 1. A plurality of unvulcanized rubber rollers 5 are housed and arranged, and each end plate 3 is fastened and fixed to the body 2 to close the body opening in a liquid-tight manner. Water, hot water or hot water is preferably filled from a water supply port (not shown) provided in the body 2 at a pressure in the range of 980 to 1960 kPa.
Thereafter, the water in the vulcanizing can is preferably heated in the range of 140 to 200 ° C. under the action of the heating means 4.

  According to these things, each unvulcanized rubber roller 5 is uniformly pressurized at a required pressure over the whole by the water surrounding it, and is uniformly heated at a required temperature throughout. become.

  And under such a state, the sponge rubber roller as a product can be manufactured by carrying out foam vulcanization of each unvulcanized rubber roller 5 for the predetermined time which adapts conditions, such as a compounding composition.

Thus, here, the unvulcanized rubber roller 5 in the vulcanizing can 1 is pressurized and heated with hot water, so that the rubber roller 5 is easily and reliably given the desired pressure and temperature. Therefore, without using a specific vulcanization mold for each unvulcanized rubber roller, the foamed cell diameter of the sponge rubber roller as a product can be made stable and fine, and the cell wall The thickness of can be stably reduced.
Moreover, since the hot water surrounding the unvulcanized rubber roller 5 pressurizes and heats the entire roller sufficiently evenly, the possibility of occurrence of flash on the product roller is completely removed, and the cell diameter, roller Excellent uniformity in hardness, charging resistance and the like can be achieved.

  1 and 2, the heating means 4 is disposed inside the vulcanizing can body 2, and the heating means 4 has a body portion 2 as shown in a sectional view in FIG. 3. In this case, surrounding the outer peripheral side of the arranged heating means 4 with the heat insulating member 6 increases the thermal efficiency. Is preferable.

  By the way, when foaming and vulcanizing the unvulcanized rubber roller 5 using the vulcanizing can 1 as described above, as described above, water and hot water are introduced into the vulcanizing can 1 in the work process. Alternatively, after filling hot water with a predetermined set pressure of 980 kPa or more and heating the water in the vulcanization can to a predetermined value within the range of 140 to 200 ° C., the vulcanization can be started. It is possible to pressurize the water to the set pressure after starting the heating of the inner water, and thus vulcanize, and to simultaneously heat and pressurize the water in the vulcanizing can. In any case, the hot water temperature is set to a predetermined set value of 980 kPa or higher before reaching the decomposition temperature of the blowing agent, most often in the range of 100 to 140 ° C. With the expansion ratio, the foam cell diameter is fine and uniform, Preferable for Le wall thickness to produce a thin sponge rubber roller.

  This means that the pressure of the hot water is within 1 minute when the degree of vulcanization reaches a predetermined value suitable for the composition of the rubber roller before the foam vulcanization of the rubber roller is completed. This is more conspicuous when the pressure is reduced to a value of 500 kPa or less. According to this, the foamed cell diameter can be further refined, the cell diameter can be effectively uniformed, and the cell wall thickness can be further increased. It can be made thinner.

4 to 6 are diagrams illustrating this, and as shown in FIG. 4, the pressure is set to a predetermined value after the temperature of the water in the vulcanization can reaches the decomposition temperature of the foam (t ₂ ). When the set value (1470 kP) is used, the cell diameter of the foam vulcanized sponge rubber roller is 250 μm on average and the cell wall thickness is average regardless of the pressure reduction timing, pressure reduction speed, etc. As shown in FIG. 5, after the heating of water was started, the temperature became the decomposition temperature of the foaming agent, while the cell diameter was increased and the cell wall thickness was also increased. If the pressure is set to a predetermined value before reaching (t ₂ ), for example, when the degree of vulcanization reaches about 80% before foam vulcanization of the unvulcanized rubber roller is completed, The pressure is less than 500 kPa within 1 minute, for example By rapidly depressurizing to kPa, the cell diameter can be in the range of 50 to 100 μm and the cell wall thickness can be in the range of 10 to 50 μm. Met.
On the other hand, as shown in FIG. 6, when the applied pressure is reduced to 500 kPa over 1.5 minutes or 2 minutes, the cell diameter is 120 μm even if the cell wall thickness can be 20 μm. It turns out that it becomes the above big value.

  In this way, in order to prevent an unexpected increase in the internal pressure of the vulcanized can caused by the thermal expansion of water in the vulcanized can when the unvulcanized rubber roller 5 is foamed and vulcanized, the vulcanized can 1 is preferably provided with a pressure adjusting means that absorbs the thermal expansion of water and maintains the internal pressure of the vulcanizing can at a predetermined constant value.

FIG. 7 shows an example, and the pressure adjusting means shown in FIG. 7A is a gas, preferably an inert gas packed bed 8 above the water packed bed 7 in the vulcanizing can 1. , And a pressure control valve 10 is provided in the gas supply / exhaust passage 9 for the gas filling layer 8.
According to this pressure adjusting means, when the filling gas pressure exceeds a predetermined set pressure due to the thermal expansion of water, the pressure control valve 10 is opened to allow the discharge of the vulcanizing can internal pressure, whereby the internal pressure is increased. Can be reliably maintained at the set value even in the presence of thermal expansion of water.

FIG. 7B shows that the pressure adjusting means is connected to the vulcanizing can 1 and allows a part of the water filled in the vulcanizing can 1 to flow in, and is preferably a gas above the water surface. The buffer tank 12 is filled with an inert gas 11, a gas supply / degassing passage 13 for the buffer tank 12, and a pressure control valve 14 provided in the passage 13.
In this adjusting means, when the gas pressure in the buffer tank 12 exceeds a set value due to the thermal expansion of the water in the vulcanizing can 1, the pressure control valve 14 is opened to release the excess pressure. Also, the inside of the vulcanizing can can be reliably maintained at a predetermined set value.

It is a basic diagram which illustrates the vulcanization can used for implementation of this invention. It is a figure which illustrates the accommodation arrangement process of the unvulcanized rubber roller to a vulcanization can. It is an approximate line sectional view which illustrates other vulcanization cans. It is a graph which illustrates one timing which makes pressurizing force a set value. It is a graph which shows embodiment of this invention. It is a graph which shows other embodiment of this invention. It is an approximate line sectional view which illustrates a pressurization adjustment means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vulcanization can 2 Body part 3 End plate 4 Heating means 5 Unvulcanized rubber roller 6 Heat insulation member 7 Water filling layer 8 Gas filling layer 9, 13 Passage 10, 14 Pressure control valve 11 Gas 12 Buffer tank

Claims (4)

  When the unvulcanized rubber roller after molding is foamed and vulcanized under heating and pressurization with hot water, the hot water temperature is set to a predetermined value within the range of 140 ° C to 200 ° C, and the hot water temperature is Before reaching the decomposition temperature of the foaming agent of the vulcanized rubber roller, the pressurizing pressure is increased to a predetermined set pressure of 980 kPa or more, and then the pressurizing pressure is within one minute before the foam vulcanization of the rubber roller is completed. And a method for producing a sponge rubber roller in which the pressure is reduced to a value of 500 kPa or less.   The method for producing a sponge rubber roller according to claim 1, wherein the pressure is set to a predetermined set pressure at the start of vulcanization.   The method for producing a sponge rubber roller according to claim 1 or 2, wherein the applied pressure before depressurization is maintained at a predetermined set pressure by pressure adjusting means for absorbing thermal expansion of water.   The method for producing a sponge rubber roller according to any one of claims 1 to 3, wherein a foamed cell diameter after completion of foam vulcanization is 100 µm or less and a thickness of the cell wall is 50 µm or less.

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