JP5641894B2 - Rubber processing aids - Google Patents

Description

  The present invention relates to a rubber processing aid.

  A tire is configured by combining a number of members made of crosslinked rubber. In manufacturing the tire, a rubber composition is prepared. The rubber composition is obtained by mixing a base rubber with chemicals such as a reinforcing agent and a filler.

  An open mill may be used for manufacture of a rubber composition. The open mill has a front roll and a rear roll. This open mill is sometimes simply referred to as a roll.

  In this open mill, rubber is introduced between the front roll and the rear roll. When the front roll and the rear roll rotate, the rubber is caught between both rolls. The rubber passes through the gap between both rolls from top to bottom. During this passage, the rubber generates heat, and the plasticization of the rubber is promoted. Usually, since the rotation speed of the front roll is set to be larger than that of the rear roll, the plasticized rubber is wound around the front roll.

  In producing the rubber composition, the base rubber is put into an open mill. After the base rubber is wound around the front roll, the operator mixes the base rubber with chemicals while turning back with a knife. When all the chemicals are mixed, the thinning is repeated several times to complete the rubber composition. This series of operations is also called kneading. An example of a rubber processing method using an open mill is disclosed in Japanese Patent Laid-Open No. 2003-89112.

JP 2003-89112 A

  In rubber kneading work using an open mill, rubber may not stick to the surface of the roll and may float from this surface. In this case, the rubber does not wrap around the roll and sagging occurs. Such a phenomenon is also called bagging. When bagging occurs, not only can not be turned back, but the operator must manually press the rubber against the roll, which is dangerous to work.

  An aqueous solution containing protein may be applied to the surface of the roll. When this aqueous solution is applied to the surface, the protein solidifies and a film is formed. This film can contribute to the adhesion of rubber. Use of this aqueous solution can suppress bagging. However, on the other hand, there is a problem that odor is generated and this odor hinders the working environment.

  An object of the present invention is to provide a rubber processing aid capable of preventing the occurrence of bagging and odor.

  The rubber processing aid according to the present invention is used by being applied to the surface of a roll and contains protein and disaccharide.

  Preferably, in this rubber processing aid, the concentration of the disaccharide is 0.2% by mass or more and 5.0% by mass or less. Preferably, the disaccharide is trehalose.

  Preferably, in the rubber processing aid, the protein concentration is 2% by mass or more and 25% by mass or less. Preferably, the protein is derived from egg white.

The rubber processing method according to the present invention includes:
(1) a step of applying a rubber processing aid containing protein and disaccharide to the surface of the roll;
(2) including a step of introducing rubber and winding the rubber around the roll.

  Preferably, in this rubber processing method, in the coating step, the surface temperature of the roll is 45 ° C. or higher and 80 ° C. or lower.

  According to the rubber processing aid according to the present invention, bagging and odor generation are prevented.

FIG. 1 is a plan view showing a part of an open mill used in a rubber processing method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is an enlarged cross-sectional view illustrating a part of FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 and FIG. 2 show a part of an open mill 2 used in a rubber processing method according to an embodiment of the present invention. This open mill 2 can knead or knead rubber.

  The open mill 2 includes a pair of rolls 4 and a pair of roll guides 6. The pair of rolls 4 are arranged side by side. Each roll 4 has a cylindrical shape. Although not shown, the open mill 2 further includes temperature adjusting means. In the open mill 2, the temperature of the surface 8 of each roll 4 (hereinafter, surface temperature) can be adjusted by the temperature adjusting means.

  1 and 2, the front roll 4a is located on the left side, and the rear roll 4b is located on the right side. The front roll 4a can rotate around the axis LA in the direction indicated by the arrow A. The rear roll 4b can rotate around the axis LB in the direction indicated by the arrow B. In FIG. 2, rubber is indicated by the symbol R. The rubber R is wound around the front roll 4a.

  A gap 10 exists between the front roll 4a and the rear roll 4b. In FIG. 1 and FIG. 2, the size of the gap 10 is indicated by a double-pointed arrow DG. This size DG is represented by the distance between the front roll 4a and the rear roll 4b.

  The open mill 2 is configured such that the front roll 4a can slide in the front-rear direction. By this slide, the size DG of the roll gap 10 is adjusted.

  A pair of roll guide 6 is arrange | positioned at predetermined intervals. In the open mill 2, each roll guide 6 is fixed by holding means (not shown). The roll guide 6 stops the flow of the rubber R pushed out in the left-right direction along the roll gap 10.

  In the rubber processing method using the open mill 2, each roll 4 is rotated and the rubber R is put into the open mill 2. The rubber R is bitten between the rolls 4a and 4b by the charging. The rubber R passes between the rolls 4a and 4b from top to bottom. In the open mill 2, since the front roll 4a is adjusted to rotate faster than the rear roll 4b, the rubber R is wound around the front roll 4a.

  In this rubber processing method, an operator stands in front of the front roll 4a, cuts back the rubber R wound around the front roll 4a with a knife, and adds the kneading to the rubber R. In this operation, the size DG of the roll gap 10 is adjusted, and the amount of the bank 12 is appropriately maintained.

  In this rubber processing method, various base rubbers can be used as the rubber R. Examples of the base rubber include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber, and ethylene propylene rubber. As the rubber R, a rubber composition containing a base rubber containing chemicals such as a reinforcing agent and a filler can also be used.

  FIG. 3 is an enlarged cross-sectional view illustrating a part of FIG. FIG. 3 shows a portion of the surface 8 of the front roll 4a around which the rubber R is wound. As shown in the figure, a film 14 is formed on the surface 8 of the front roll 4a. The rubber R is wound around the front roll 4a through the film 14.

  In this rubber processing method, the coating 14 is obtained by applying a rubber processing aid to the surface 8 of the front roll 4a. This auxiliary agent is used by being applied to the front roll 4a. This adjuvant contains proteins and disaccharides.

  In this rubber processing method, when the adjuvant is applied to the surface 8 of the front roll 4a, the protein is denatured and solidified. By this solidification, a film 14 is formed on the surface 8 of the front roll 4a. This film 14 contains denatured protein. The coating 14 can contribute to the adhesion of the rubber R. The coating 14 can suppress the rubber R from lifting from the surface 8 of the roll 4a. In this rubber processing method, since the rubber R is in close contact with the front roll 4a, bagging is effectively prevented. An operator can perform work such as turning back reliably and safely. This rubber processing method can contribute to improvement of work efficiency.

  In this rubber processing method, examples of the protein include those derived from egg white, those derived from milk, and those derived from soy milk. Egg white albumin is exemplified as one derived from egg white. Casein is exemplified as the one derived from milk. A glycinin is illustrated as what originates in soymilk. From the viewpoint that bagging can be effectively prevented, this protein is preferably derived from egg white.

  As mentioned above, the adjuvant contains a disaccharide. For this reason, the film 14 contains disaccharides. This disaccharide can contribute to the reduction of odor caused by protein. This adjuvant can improve the working environment. Moreover, this disaccharide can contribute to the improvement of the adhesion of the rubber R. For this reason, this disaccharide can also contribute to the reduction | decrease of the density | concentration of the protein contained in this adjuvant. In the rubber processing method using this auxiliary agent, the working environment can be greatly improved without impairing the adhesion of the rubber R.

  In this rubber processing method, examples of the disaccharide include trehalose, sucrose, maltose, and lactose. Trehalose is preferable as the disaccharide from the viewpoint that odor can be reduced while preventing bagging.

  In this rubber processing method, the auxiliary agent can further contain a dispersion medium. This dispersion medium can adjust the protein concentration appropriately. This dispersion medium can appropriately adjust the concentration of the disaccharide. Examples of the dispersion medium include water, methanol, and ethanol. From the viewpoint of preventing denaturation of proteins present in the auxiliary agent before application to the roll 4, water is preferable as the dispersion medium.

  In this rubber processing method, the auxiliary agent is applied to the front roll 4 a before the rubber R is put into the open mill 2. After coating, a film 14 is gradually formed on the surface 8 of the front roll 4a. For this reason, the time from the application of the auxiliary agent to the start of rubber kneading can affect the quality of the film 14. From the viewpoint that a high-quality film 14 can be obtained, this time is preferably 10 seconds or more, and more preferably 20 seconds or more. From the viewpoint that the quality of the film 14 can be stably maintained, this time is preferably 60 seconds or less, and more preferably 40 seconds or less.

  In this rubber processing method, the auxiliary agent is applied by an appropriate method. While rotating the roll 4a, the auxiliary agent may be applied to the roll 4a with a brush, or the auxiliary agent may be applied to the roll 4a using a spray or the like.

  In this rubber processing method, the surface temperature of the front roll 4a is appropriately adjusted in the reinforcing agent application step from the viewpoint of easy formation of the coating 14 and durability. From the viewpoint of easy formation of the film 14, the surface temperature of the front roll 4 a is preferably 45 ° C. or higher, and more preferably 50 ° C. or higher. From the viewpoint of durability of the film 14, the surface temperature is preferably 80 ° C. or lower, and more preferably 70 ° C. or lower. In this rubber processing method, the surface temperature may be adjusted before application of the auxiliary agent or after application of the auxiliary agent.

  In this rubber processing method, the protein concentration is preferably 2% by mass or more and 25% by mass or less. By setting this concentration to 2% by mass or more, the film 14 having excellent adhesion can be obtained. From this viewpoint, the concentration is more preferably 2.5% by mass or more, and particularly preferably 3% by mass or more. By setting the concentration to 25% by mass or less, excessive adhesion of the rubber R can be prevented. In this rubber processing method, the film 14 can effectively prevent bagging without impairing workability. Since the disaccharide compounded with this protein can contribute to the improvement of adhesion, the concentration of this protein is more preferably 10% by mass or less from the viewpoint of preventing excessive adhesion of rubber R and reducing odor. 5 mass% or less is further more preferable, and 4 mass% or less is especially preferable. The protein concentration can be determined by measuring the absorbance at 280 nm by ultraviolet spectrophotometry.

  In the rubber processing method, the disaccharide concentration is preferably 0.2% by mass or more and 5.0% by mass or less. By setting this concentration to 0.2% by mass or more, the odor of the film 14 is effectively prevented. This adjuvant can contribute to the improvement of the working environment. In this respect, the concentration is more preferably equal to or greater than 1.0% by mass. By setting the concentration to 5.0% by mass or less, excessive adhesion of the rubber R can be prevented. In this respect, the concentration is more preferably equal to or less than 4.0% by mass. The concentration of the disaccharide is calculated based on the mass of the disaccharide added when the auxiliary agent is produced.

  In this rubber processing method, the ratio of the mass of the disaccharide to the mass of the protein contained in the adjuvant is preferably 0.008 or more and 2.5 or less. By setting this ratio to 0.008 or more, the auxiliary agent can effectively contribute to the reduction of odor. In this respect, the ratio is more preferably equal to or greater than 0.04. By setting this ratio to 2.5 or less, excessive adhesion of the rubber R can be prevented. From this viewpoint, the ratio is more preferably 2 or less.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Preparation of base rubber and chemicals]
According to the recipe shown in Table 1 below, the base rubber and the chemicals were weighed to prepare the recipes A and B. In Formulation A, styrene-butadiene rubber (trade name “Sumitomo Rubber Grade” manufactured by Sumitomo Chemical Co., Ltd.) and natural rubber (“SIR20” manufactured by Indonesia) were used as the base rubber. As the reinforcing agent, carbon black (trade name “N351M” manufactured by Mitsubishi Chemical Corporation) was used. As a softening agent, aromatic oil (trade name “30K aromatic oil” manufactured by Mobil Corporation) was used. As the filler, zinc white (trade name “Zinc Oxide” manufactured by Mitsui Kinzoku Co., Ltd.) was used. As the lubricant, stearic acid (trade name “stearic acid” manufactured by NOF Corporation) was used. Sulfur (trade name “Sulfur Powder” manufactured by Karuizawa Chemical Co., Ltd.) was used as the crosslinking agent. As other chemicals, a vulcanization accelerator (trade name “Accelerator CZ” manufactured by Ouchi Shinsei Chemical Co., Ltd.) was used. In Formulation B, the same base rubber and chemicals as in Formulation A are used except for styrene bradiene rubber (trade name “SBR1502” manufactured by Sumitomo Chemical Co., Ltd.) and carbon black (“N660” manufactured by Mitsubishi Chemical Co., Ltd.). It was.

[Example 1]
Only egg white was removed from the egg and stirred in a beaker for 10 minutes. Stirring was carried out until the egg white turned into meringue. The stirred egg white was filtered to obtain a filtrate. This filtrate contains a protein derived from egg white. Trehalose was used as the disaccharide. The filtrate and disaccharide were mixed with water as a dispersion medium to obtain an auxiliary agent. The concentration of protein was 2.5% by mass, and the concentration of disaccharide was 1.0% by mass.

  The surface temperature of the front roll was adjusted to 70 ° C. An adjuvant was applied to the surface of the previous roll. Application of this adjuvant was carried out using a spray while rotating the front roll. After 30 seconds from the application, styrene butadiene rubber and natural rubber were put into an open mill. The rubber was cut back using a knife, and a chemical such as a filler was mixed while appropriately adjusting the roll gap. After all the chemicals had been charged, thinning was repeated several times to obtain a rubber composition of Formulation A. A 22-inch open mill was used for the production of this rubber composition. The roll diameter was 558 mm, the roll gap size DG was 12 mm, the rotation speed of the front roll was 18.0 m / min, and the rotation speed of the rear roll was 17.3 m / min.

[Example 2-8 and Example 13-21 and Comparative Example 1-6]
A rubber composition of Formulation A was obtained in the same manner as in Example 1 except that the protein concentration and disaccharide concentration were as shown in Tables 2, 3, 5 and 6 below.

[Examples 9-12]
A rubber composition of Formulation A was obtained in the same manner as in Example 1 except that the surface temperature of the front roll was as shown in Table 4 below.

[Examples 22-23 and Comparative Examples 7-8]
A rubber composition was obtained in the same manner as in Example 1 except that the protein concentration and disaccharide concentration were as shown in Table 6 below, and the formulation B was prepared.

[Evaluation of rubber kneading work]
The work situation of rubber kneading was evaluated. The evaluation items were the bagging state, the adhesion between the roll and the rubber, and the state of odor generation. The evaluation results are shown in Tables 2 to 6 below. In the evaluation regarding the state of bagging, the presence or absence of bagging was confirmed. In the table, “G” indicates that bagging has not occurred, and “NG” indicates that bagging has occurred. In the evaluation results regarding the adhesion between the roll and the rubber, “A” indicates that the rubber is too close to be peeled off from the roll, and “B” indicates that the rubber is appropriately adhered to the roll and is easy to work (preferred state). The case where the rubber is not closely attached to the roll is represented by “C”, and the case where the rubber is not adhered to the roll is represented by “D”. In the evaluation results regarding the odor generation status, “1” indicates that the odor is so difficult that it is difficult to resist, “2” indicates that it is difficult, and “3” indicates that it is slightly irritating (a level that can be confused). The case where the user does not smell is “4”, and the case where he / she feels a good smell is indicated by “5”.

  As shown in Tables 2 to 6, the rubber processing method of the example has higher evaluation than the rubber processing method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The method described above can be applied to the production of rubber compositions used for various rubber products.

2 ... Open mill 4, 4a, 4b ... Roll 6 ... Roll guide 8 ... Surface 10 ... Gap 12 ... Bank 14 ... Film

Claims (7)

It is used by applying to the surface of the roll,
Contains proteins and disaccharides ,
The concentration of the disaccharide is 0.2% by mass or more and 5.0% by mass or less,
A rubber processing aid having a protein concentration of 2% by mass to 25% by mass . The rubber processing aid according to claim 1, wherein the disaccharide is trehalose. The rubber processing aid according to claim 1 or 2 , wherein the protein is derived from egg white. The rubber processing aid according to any one of claims 1 to 3, wherein a ratio of a mass of the disaccharide to a mass of the protein is 0.008 or more and 2.5 or less. A rubber processing aid comprising a protein and a disaccharide, wherein the concentration of the disaccharide is 0.2% by mass or more and 5.0% by mass or less, and the concentration of the protein is 2% by mass or more and 25% by mass or less. A process applied to the surface of the roll;
A method of processing rubber using a rubber processing auxiliary agent comprising a step of introducing rubber and winding the rubber around the roll. The rubber processing method using the rubber processing aid according to claim 5 , wherein in the coating step, the surface temperature of the roll is 45 ° C. or higher and 80 ° C. or lower. The rubber using the rubber processing aid according to claim 5 or 6, wherein in the rubber processing aid, the ratio of the mass of the disaccharide to the mass of the protein is 0.008 or more and 2.5 or less. Processing method.

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