JP2006070207A - Manufacturing method of silicone rubber and silicone rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the improvement of the tearing strength of a silicone rubber without changing its constitution. <P>SOLUTION: The vulcanization process of the manufacturing method is performed by dividing it into the former vulcanization process of a step S200 and the latter vulcanization process of a step S300 when adding vulcanizing agent to an unvulcanized silicone rubber and carrying out vulcanization. The tearing strength of the silicone rubber composition obtained is improved comparing with the tearing strength of the silicone rubber obtained by the conventional method in which the vulcanization process is not divided when adding a vulcanizing agent. When this method is used, the tearing strength can be improved by only changing the procedure of adding a vulcanizing agent to a commercially available unvulcanized silicone rubber compound for example without changing the constitution of a silicone rubber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to silicone rubber, and in particular, is a technique effective for improving the tear strength of silicone rubber.

  Silicone rubber is widely used in various fields such as automobiles, electricity, electronics, OA equipment, food, and medicine because it is excellent in heat resistance, cold resistance, electrical properties, weather resistance, hygiene, and the like.

  Although silicone rubber has excellent characteristics as described above, it has been pointed out that it is insufficient in terms of strength compared to general organic rubber. For this reason, various improvements in the tensile strength and tear strength of silicone rubber have been attempted. In particular, regarding the tear strength, it is difficult to improve the strength, and the present situation is that the improvement has not been achieved.

  As a method for molding silicone rubber, a method in which a necessary amount of a required vulcanizing agent is blended in a silicone rubber compound, and then a method of heat-pressure molding or extrusion heat molding is generally employed. However, since the silicone rubber molded product obtained by such a molding method does not have sufficient tear strength, defects such as tearing and cracking are likely to occur when molding a molded product having a complicated shape. In applications where wear, scratching, or the like is a concern, problems such as inability to withstand use due to easy tearing have been pointed out.

In order to give high tear strength to silicone rubber, the addition of inorganic reinforcing agents such as surface-treated fumed silica, the combination of silicone polymers that make the crosslink density dense, the addition of organic reinforcing agents such as resins, etc. Various methods have been proposed. For example, Patent Document 1 discloses that both tensile strength and tear strength are improved by blending organopolysilalkylenesiloxane as a siloxane component of a silicone rubber composition.
JP-A-5-247349

  The high strength type silicone rubber currently on the market has a tear strength of about 30 to 40 N / mm, and it is pointed out that the tear strength is still insufficient in the field of use. At present, the tear strength is required to be improved more than ever.

  As described above, the conventional techniques for improving the tear strength have been mainly performed from the viewpoint of the silicone rubber composition. This approach from the aspect of the composition can be applied effectively when silicone rubber is produced by adding various compounding agents from the raw rubber state, but by adding a vulcanizing agent to a commercially available silicone rubber compound. It is difficult to apply when manufacturing silicone rubber.

  Therefore, the present inventor does not attempt to improve the tear strength from the surface of the composition, but from the standpoint of producing silicone rubber using a commercially available silicone rubber compound, a technique for improving the tear strength. I thought it was necessary.

  On the other hand, the inventor has fully recognized through practical experience that control of the degree of crosslinking is extremely important for improving the mechanical strength of silicone rubber, based on many years of knowledge. Therefore, in order to break the current situation, paying attention to the point of adding a vulcanizing agent to the silicone rubber compound, that is, from the viewpoint of control of the crosslinking technology, whether the improvement of the tear strength of the silicone rubber can be achieved so far Tried to develop technology based on new ideas.

  An object of the present invention is to improve the tear strength of silicone rubber without changing the composition.

  The present inventor reexamined the vulcanization method by reviewing in detail the conventional vulcanization method for silicone rubber and conducting experiments each time. As a result, it was found for the first time that the tear strength can be improved by adding the vulcanizing agent in a plurality of times and vulcanizing each time the vulcanizing agent is added.

  The present invention has been made on the basis of new knowledge backed up by such experimental facts, and is a technology that can improve the tear strength of a silicone rubber having the same composition by changing the vulcanization method. is there. Since it is possible to improve the tear strength by changing the vulcanization method without being bound by the components of the composition, it is extremely easy to respond to the field from the standpoint of using a commercially available silicone rubber compound, and the present invention is an extremely meaningful invention. is there.

  That is, the method for producing a silicone rubber according to the present invention includes a pre-vulcanization step in which a vulcanizing agent is added to an unvulcanized silicone rubber and partially vulcanized, and a partially vulcanized silicone rubber obtained in the pre-vulcanization step. And a post-vulcanization step in which a vulcanizing agent is added and vulcanized. The partial vulcanization or partial vulcanization referred to here is a vulcanized state that can be rolled (kneaded) with two rolls. Such a vulcanized state has a partial vulcanized state, but it can be said to be vulcanized to a state in which the form is not fixed and the fluidity is obtained and further kneading is possible.

  In this configuration, the amount of the vulcanizing agent added in the pre-vulcanization step is set to 0.001 part by weight or more and 1.0 part by weight or less with respect to 100 parts by weight of the unvulcanized silicone rubber. It is characterized by.

  Further, in the method for producing a silicone rubber having any one of the above structures, the unvulcanized silicone rubber is methylphenyl silicone rubber.

  In any one of the above-described configurations, the vulcanizing agent is a peroxide vulcanizing agent.

  In any one of the above-described configurations, the vulcanizing agent added in the pre-vulcanization step and the vulcanizing agent added in the post-vulcanization step are different vulcanizing agents.

  Moreover, the silicone rubber composition obtained by vulcanizing the unvulcanized silicone rubber of the present invention is characterized by being produced by any one of the above-described methods for producing a silicone rubber.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  By applying the present invention, it is possible to improve the tear strength of the silicone rubber without changing the composition.

  Such an improvement in tear strength can be dealt with by a vulcanization method without being restricted by the components of the silicone rubber composition. Therefore, by purchasing a commercial product of an unvulcanized silicone rubber compound, the vulcanized silicone rubber can be used. It can be easily handled at the manufacturing site.

  Silicone rubber produced by the method for producing silicone rubber according to the present invention has higher tear strength than conventional silicone rubber, so that silicone rubber can be applied to fields such as anti-vibration rubber, which has been considered difficult until now. Can be planned.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a flowchart showing a process procedure of an embodiment of the method for producing silicone rubber of the present invention. FIG. 2 is a flowchart showing a process procedure in the conventional method for producing silicone rubber.

  As shown in FIG. 1, in the method for producing silicone rubber of the present invention, unvulcanized silicone rubber is prepared in step S100. As the unvulcanized silicone rubber to be used, a commercially available silicone rubber compound may be used simply. At present, silicone rubber compounds having various compositions are commercially available, and can be appropriately selected according to the application product.

  The present invention can be applied to, for example, dimethyl silicone rubber, methylphenyl silicone rubber, fluorosilicone rubber, and the like.

  Moreover, it is a matter of course that an unvulcanized silicone rubber compound may be produced independently by appropriately kneading the compounding agent into the raw rubber from the beginning without using a commercially available silicone rubber compound.

  In the pre-vulcanization process of step S200, a vulcanizing agent is added to the unvulcanized silicone rubber prepared in step S100 to perform vulcanization. As shown in FIG. 1, the pre-vulcanization process of step S200 includes a process of adding a vulcanizing agent shown in step S210, a mixing process shown in step S220, and a process of heating and the like shown in step S230. ing.

  That is, in step S210, a vulcanizing agent is added to the unvulcanized silicone rubber prepared in step S100. As the vulcanizing agent to be added, for example, a vulcanizing agent in accordance with an instruction from the manufacturer may be used. If there are a plurality of types of designations, they may be appropriately selected and used according to the application. Examples of the vulcanizing agent include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, benzoyl peroxide, dicumyl peroxide, ditertiary butyl peroxide, parachlorobenzoyl peroxide, and tertiary. A peroxide-based vulcanizing agent typified by butyl cumyl peroxide, P-methylbenzoyl peroxide, or the like can be used.

  In general, commercially available unvulcanized silicone rubber compounds are specified by the manufacturer as the standard specifications, such as the type of vulcanizing agent, amount added, operating temperature, vulcanizing time, etc. Therefore, the selection may be made with reference to such standard specifications.

  On the other hand, the addition amount of the vulcanizing agent described in the standard specification describes the usage amount based on the conventional method in which the step of adding and curing the vulcanizing agent as a single step is described. The usage amount cannot be adopted in step S210 as it is.

  The present inventors have confirmed that the vulcanizing agent should be added at a ratio of 0.001 part by weight or more and 1.0 part by weight or less with respect to 100 parts by weight of the unvulcanized silicone rubber. It was. When the amount is less than 0.001 part by weight, the tear strength of the produced silicone rubber composition may not be sufficiently improved. On the other hand, when the amount exceeds 1.0 part by weight, it is difficult to perform the vulcanization operation in the post-vulcanization step. . A more preferable range is 0.005 parts by weight or more and 0.5 parts by weight or less. In such a range, the tear strength can be sufficiently improved, and the ease of workability such as mixing in the post-vulcanization process can be sufficiently secured.

  Thus, in step S210, the vulcanizing agent is added to the unvulcanized silicone rubber in the range of the above addition amount, and then in step S220, they are mixed so as to be uniform. For mixing, for example, a roll machine, a Banbury mixer, a kneader or the like may be used.

  After mixing in step S220, processing such as heating is performed in step S230. Depending on the vulcanizing agent used, it may be heated to the required temperature or, if necessary, treated at room temperature without heating. The treatment such as heating is performed in a state where the mixture of the unvulcanized silicone rubber and the vulcanizing agent is put in a Banbury mixer or a kneader. Of course, it may be once taken out from a hanbury mixer, a kneader or the like and subjected to a treatment such as heating using a separate oven.

  As described above, the heating temperature is set by appropriately considering the amount used in step S210 with reference to the standard heating temperature and the standard vulcanization time in accordance with the designation from the manufacturer.

  It is inferred that the mixture at the time when step S220 is completed is in a state where vulcanization is partially performed. The state of such a mixture is different from the state of the silicone rubber after the vulcanization is finally finished. For example, the mixture does not have a viscosity enough to be wound around a roll even when it is applied to a kneading machine in a heated state. The state remains. In terms of image, it can also be expressed as a substantially gel.

  As shown in FIG. 1, the silicone rubber mixture partially vulcanized in the pre-vulcanization step in step S200 is added with a vulcanizing agent again in the post-vulcanization step in step S300, and then the silicone rubber mixture is added. Vulcanization required for rubber. As shown in FIG. 1, the post-vulcanization process S300 includes step S310 of the vulcanizing agent addition process, step S320 of the mixing process, and step S330 of the processing process such as heating.

  That is, in step S310, the vulcanizing agent is added to the unvulcanized silicone rubber in the pre-vulcanization step, and the vulcanizing agent is added again to the partially vulcanized silicone rubber that has obtained a partially vulcanized state. As such a vulcanizing agent, the same vulcanizing agent as used in the pre-vulcanizing step of Step S200 may be used. However, in some cases, different vulcanizing agents can be used.

  The amount of addition in the re-addition of the vulcanizing agent is 0.05 to 1.5 parts by weight with respect to 100 parts by weight of the unvulcanized silicone rubber. It was confirmed that it should be added at a ratio. If it is less than 0.05 part by weight, the final vulcanized state required for the silicone rubber cannot be sufficiently obtained, and the tear strength is not improved. On the other hand, when the amount exceeds 1.5 parts by weight, the silicone rubber becomes too hard. More preferably, they are 0.1 weight part or more and 1.0 weight part or less. Within such a range, sufficient silicone rubber softness can be secured without making it harder than necessary, and sufficient tear strength can be secured.

  In addition, although the addition amount of the vulcanizing agent in the post-curing process is shown to be defined with respect to 100 parts by weight of the unvulcanized silicone rubber, it should be defined with respect to 100 parts by weight of the partially vulcanized silicone rubber. Also good.

  In this manner, the partially vulcanized silicone rubber to which the required amount of vulcanizing agent has been added in step S310 is mixed almost uniformly in step S320. This mixing is performed using, for example, a roll machine, a Banbury mixer, a kneader or the like.

  After mixing in step S320, processing such as heating is performed in step S330, and vulcanization is performed in accordance with the addition of the vulcanizing agent. As the treatment such as heating, vulcanization was performed by heating in accordance with the vulcanizing agent to be used.

  Such processing such as heating is performed in a state where the mixture obtained in step S320 is placed in a required mold.

  After the completion of the post-curing step in step S300, as shown in FIG. 1, if necessary, in the aging step in step S400, a silicone rubber molded product formed in a required shape is taken out from the mold and is again required. Aging is performed by heating to temperature. Aging is performed in an oven at 200 ° C. for 4 hours, for example. At this time, the aging conditions may be appropriately set according to the silicone rubber to be aged. The characteristics can be stabilized by performing an aging process as necessary.

  As described above, in the method for producing a silicone rubber according to the present invention, the vulcanizing agent is not added at once, but vulcanized, and the vulcanizing agent is added in several times. Each time it is added, a treatment such as heating is performed to finally complete the vulcanization. That is, instead of adding the vulcanizing agent necessary to complete the vulcanization at once, a part of the amount of vulcanizing agent necessary to complete the vulcanization is added, resulting in partial vulcanization. Then, the vulcanizing agent is added again and then vulcanized to fix the form and complete the product.

  Regarding the tear strength of silicone rubber, microscopically, the structure of silicone rubber has a loose part and a dense part of the cross-link, so that even when the required tension is applied to the silicone rubber, It is presumed that the tear strength is improved because tension is relaxed in the sparse part.

  Therefore, as in the present invention, when a vulcanizing agent is added separately and vulcanized by applying a heat treatment or the like for each addition, the vulcanizing agent is added all at once and vulcanized. In comparison, re-kneading before and after re-addition of the vulcanizing agent causes twisting in the partially cross-linked site, forming a strained part and a relaxed part, and double dispersion / relaxation combined with the dense structure It is thought that the tear strength is improved by working. The detailed mechanism of the effectiveness of the present invention has to wait for further research, but at the present stage, the present inventor speculates as described above.

  In order to facilitate understanding of the characteristic vulcanization procedure in the present invention, FIG. 2 shows a conventional vulcanization technique. As shown in FIG. 2, in the conventional vulcanization procedure, unvulcanized silicone rubber is prepared in step S100. The unvulcanized silicone rubber prepared in step S100 is vulcanized in step S500.

  As shown in FIG. 2, the vulcanization process of step S500 includes step S510 for adding a vulcanizing agent necessary for completing the vulcanization, and the added vulcanizing agent is uniformly mixed with the unvulcanized silicone rubber. Step S520, and Step S530 for performing a treatment such as heating on the mixture of the unvulcanized silicone rubber and the vulcanizing agent. The mixture of the unvulcanized silicone rubber and the vulcanizing agent is subjected to a treatment such as heating called primary vulcanization in a state where it is put in a mold.

  Thereafter, a silicone rubber molded product is taken out from the mold, and as shown in step S400 in FIG. 2, an aging treatment is performed separately at a required temperature and time in an oven or the like as necessary to obtain a product. The aging process shown in step S400 is called secondary vulcanization with respect to the primary vulcanization. FIG. 1 also shows steps corresponding to primary vulcanization and secondary vulcanization.

  In the configuration of the present invention, as shown in the procedure of FIG. 1, it can be considered that a partial vulcanization step is provided before the primary vulcanization in the conventional method shown in FIG. In the present invention, unlike the conventional method, the vulcanizing step of adding and treating the vulcanizing agent is performed in a plurality of times.

  Even if the silicone rubber produced by the method for producing silicone rubber according to the present invention described above is a silicone rubber having the same composition, it is compared with the silicone rubber produced by applying the silicone rubber production method of the conventional configuration. The tear strength is improved.

  In addition, regarding the silicone rubber produced by the method for producing silicone rubber of the present invention, a unique tearing phenomenon was confirmed in the tear strength test.

  When a normal vulcanized silicone rubber product is cut and torn, it breaks easily along the cut. On the other hand, in the case of a commercially available high-strength silicone rubber product with an improved tensile strength, the tear progresses slightly along the break, but then the tear changes in either the right or left direction with respect to the break. The so-called notty tear is cut.

  However, in the silicone rubber product with improved tear strength produced by the production method of the present invention, it was confirmed that the tear progresses in both the left and right directions with respect to the cut. Since the strain stress is relaxed by tearing in both the left and right directions as compared with the case of tearing in either the left or right direction, it is presumed that the tear strength has increased dramatically as a result.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the case shown in FIG. 1, the case where one post-vulcanization step, such as heat treatment in a mold, is provided after the pre-vulcanization step. Here, a plurality of pre-vulcanization steps are provided. It may be repeated once. That is, step S210 to step S230 are repeated a plurality of times, and then the post-vulcanization step is performed. At this time, the total addition amount of the vulcanizing agent in the plurality of pre-vulcanization steps is appropriately set within a range not exceeding the range of the addition amount of the vulcanizing agent in the pre-vulcanization step of the present invention.

  Further, in the above pre-vulcanization step, the explanation was made using unvulcanized silicone rubber, but it is also possible to use a generally available silicone rubber compound with added vulcanizing agent instead of this unvulcanized silicone rubber. it can. In this case, for example, by adjusting the amount of the vulcanizing agent relative to the unvulcanized silicone rubber by, for example, combining the kneaded silicone rubber with the vulcanizing agent separately and kneading the silicone rubber without the vulcanizing agent. The present invention can be applied.

  Further, as shown in FIG. 1, in the above description, in the pre-vulcanization process, the case where the mixing of the vulcanizing agent and the treatment process such as heating after the mixing are separated into separate processes has been described. The equal processing may be performed as one process, that is, heating or the like while mixing. That is, in such a case, step S220 and step S230 shown in FIG. 1 are shown as a single process.

  In the description of the embodiment, as illustrated in FIG. 1, the case where the aging process is provided after the post-vulcanization process is illustrated. However, when the present invention is applied, the aging process may not be provided.

  Next, the silicone rubber production method according to the present invention described in the above embodiment and the silicone rubber produced by the production method will be verified based on the following examples to improve the tear strength.

  In Example 1, silicone rubber was manufactured according to the flow shown in FIG. 1 using silicone rubber compound TSE260-7U manufactured by GE-Toshiba Silicone as unvulcanized silicone rubber.

  In the pre-vulcanization process, as shown in FIG. 1, corresponding to step S210, 100 parts by weight of silicone rubber compound TSE260-7U is mixed with 2,5-dimethyl-2,5bis (peroxide-based vulcanizing agent). 0.02 part by weight of t-butylperoxy) hexane was added. Corresponding to step S220, these mixtures were uniformly mixed with two rolls of a roll mixer. Corresponding to step S230, the uniformly mixed product was heated in a gear oven at 170 ° C. for 20 minutes to perform partial vulcanization.

  The post-vulcanization process was applied to the partially vulcanized silicone rubber obtained by completing the pre-vulcanization process in this way. As shown in FIG. 1, a vulcanizing agent was added to the partially vulcanized silicone rubber obtained after completion of the pre-vulcanization process cooled to room temperature, corresponding to step S310 of the post-vulcanization process. As the vulcanizing agent, the same 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane used in the pre-vulcanization step was used. The addition amount was set to 0.1 parts by weight with respect to 100 parts by weight of the silicone rubber compound TSE260-7U.

  Then, corresponding to step S320, the mixture was uniformly mixed with two rolls of a roll mixer. Further, in accordance with step S330, the uniformly mixed material was pressed for 10 minutes under the conditions of 170 ° C. and a pressure of 9.8 MPa to prepare a 2 mm thick silicone rubber sheet. Thus, the post-vulcanization process was completed.

  The use conditions of the vulcanizing agent and the like in the pre-vulcanization step and post-vulcanization step in Example 1 are shown in a list in FIG. 3 together with the other examples. In FIG. 3, the vulcanizing agent “2,5-dimethyl-2,5-bis (t-butylperoxy) hexane” is replaced with “2,5-dimethyl” and “p-methylbenzoyl peroxide”. Each is abbreviated as “p-methylbenzo”. Moreover, the addition amount of the vulcanizing agent to be used is a ratio with respect to 100 parts by weight of the unvulcanized silicone rubber compound during both pre-curing and post-curing.

  After completion of the post-vulcanization process, the sheet prepared through the post-vulcanization process was subjected to an aging treatment by heating at 200 ° C. for 4 hours, corresponding to step S400. The physical properties of the sheet after the aging treatment were measured for four items of hardness, elongation, tensile strength, and tear strength, and the results are shown in FIG. The hardness was measured according to JIS K6253. Elongation and tensile strength tests were performed according to JIS K6521. The tear strength test was performed in the JIS K6252 not-cut angle type test.

  In Example 2, the pre-vulcanization process was performed using silicone rubber compound TSE260-7U manufactured by GE-Toshiba Silicone Co., Ltd. as unvulcanized silicone rubber in the same manner as in Example 1. 0.03 parts by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is added to 100 parts by weight of the silicone rubber compound TSE260-7U, and two roll mixers are added. The mixture was uniformly mixed using a roll and heated in a gear oven at 150 ° C. for 60 minutes for partial vulcanization.

  In Example 2, as described above, in the pre-vulcanization step, although the addition amount of the vulcanizing agent is slightly different, using the same vulcanizing agent as in Example 1, vulcanization time different from that in Example 1, Vulcanization was carried out at the vulcanization temperature.

  After cooling the partially vulcanized silicone rubber after completion of the pre-vulcanization process, again, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent and silicone rubber compound TSE260-7U100 weight 0.15 parts by weight with respect to the part, uniformly mixed using two rolls of a roll mixer, and pressed for 10 minutes under the conditions of a temperature of 170 ° C. and a pressure of 9.8 MPa for post-vulcanization. To give a sheet having a thickness of 2 mm. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG.

  In Example 3, a pre-vulcanization process was performed using a silicone rubber compound TSE260-7U manufactured by GE-Toshiba Silicone Co., Ltd. as an unvulcanized silicone rubber in the same manner as in Example 1. To 100 parts by weight of silicone rubber compound TSE260-7U, 0.01 part by weight of p-methylbenzoyl peroxide is added as a vulcanizing agent, and uniformly mixed using two rolls of a roll mixer, and a gear at 100 ° C. Partial vulcanization was performed by heating in an oven for 30 minutes.

  After cooling the partially vulcanized silicone rubber after completion of the pre-vulcanization process, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is added to 100 parts by weight of the silicone rubber compound TSE260-7U. 0.15 parts by weight with respect to the mixture, uniformly mixed using two rolls of a roll mixer, pressed for 10 minutes under conditions of a temperature of 170 ° C. and a pressure of 9.8 MPa, followed by post-vulcanization, A sheet having a thickness of 2 mm was prepared. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG. In Example 3, different vulcanizing agents were used in the pre-vulcanization step and the post-vulcanization step.

  In Example 4, the pre-vulcanization process was performed using silicone rubber compound TSE260-7U manufactured by GE-Toshiba Silicone Co., Ltd. as unvulcanized silicone rubber in the same manner as in Example 1. 0.02 parts by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane is added as a vulcanizing agent to 100 parts by weight of the silicone rubber compound TSE260-7U and mixed uniformly with a kneader. And then partially vulcanized by heating at 170 ° C. for 20 minutes. In Example 4, unlike the case of Examples 1 to 3, heating in pre-vulcanization is performed with a kneader.

  After cooling the partially vulcanized silicone rubber after completion of the pre-vulcanization process, again, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent and silicone rubber compound TSE260-7U100 weight 0.15 parts by weight with respect to the part, uniformly mixed using two rolls of a roll mixer, and pressed for 10 minutes under the conditions of a temperature of 170 ° C. and a pressure of 9.8 MPa for post-vulcanization. To give a sheet having a thickness of 2 mm. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG.

(Comparative Example 1)
For comparison of physical properties, the same vulcanized silicone rubber TSE260-7U manufactured by GE-Toshiba Silicone Co. as in Example 1 was used as the unvulcanized silicone rubber, and vulcanized under the conventional vulcanization conditions described in the manufacturer catalog. The physical properties of the obtained silicone rubber sheet are shown as Comparative Example 1 in FIG.

  Vulcanization conditions for adding 0.6 parts by weight of TC-8 (GE-Toshiba Silicone), a vulcanizing agent containing 50% 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, , A vulcanizing agent TC-8 containing 50% 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane with respect to 100 parts by weight of silicone rubber compound TSE260-7U (GE-manufactured by Toshiba Silicone Co., Ltd.) ) Was added in an amount of 0.6 parts by weight, and mixed uniformly using a two-roll roll mixer. Thereafter, pressing was performed at 170 ° C. and a pressure of 9.8 MPa for 10 minutes to prepare a 2 mm-thick silicone rubber sheet. Furthermore, the produced silicone rubber sheet was heated at 200 ° C. for 4 hours to perform an aging treatment, and the physical properties were measured in the same manner as in Examples 1 to 4, and the results are shown in FIG.

  When Examples 1-4 in FIG. 4 and Comparative Example 1 are compared, the tensile strength is substantially the same as that of the conventional method, but the tear strength (same as the tear strength) is an embodiment to which the present invention is applied. It can be seen that the cases of 1-4 are improved by about 1.4 times to about 1.6 times, and the effectiveness of the present invention can be confirmed.

(Comparative Example 2)
For comparison of physical properties, a silicone rubber sheet was obtained in the same manner as in Comparative Example 1, except that 0.3 part by weight of TC-8 as a vulcanizing agent was added in Comparative Example 1. The physical properties of the obtained silicone rubber sheet are shown as Comparative Example 2 in FIG. This comparative example compared the effects when the amount of the vulcanizing agent was halved.

  In Example 5, silicone rubber compound KE5560U (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the unvulcanized silicone rubber. In the pre-vulcanization step, 0.35 parts by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is added to 100 parts by weight of the silicone rubber compound KE5560U, and roll mixing is performed. The two rolls of the machine were mixed uniformly and heated in a gear oven at 150 ° C. for 20 minutes for partial vulcanization.

  After cooling the partially vulcanized silicone rubber after the pre-vulcanization, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is again added to 100 parts by weight of the silicone rubber compound KE5560U. 0.5 parts by weight, uniformly mixed using two rolls of a roll mixer, pressed for 10 minutes under conditions of a temperature of 170 ° C. and a pressure of 9.8 MPa, followed by post-vulcanization, The sheet was 2 mm long. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG.

  In Example 6, silicone rubber compound KE5560U (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the unvulcanized silicone rubber in the same manner as in Example 5. In the pre-vulcanization step, 0.1 parts by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane is added as a vulcanizing agent to 100 parts by weight of the silicone rubber compound KE5560U, and roll mixing is performed. The two rolls of the machine were mixed uniformly and heated in a gear oven at 170 ° C. for 20 minutes for partial vulcanization.

  In Example 6, as described above, in the pre-vulcanization step, the vulcanizing agent was used at the vulcanization temperature different from that in Example 5 using the same vulcanizing agent as in Example 5 although the addition amount of the vulcanizing agent was slightly different. Sulfur was performed.

  After cooling the partially vulcanized silicone rubber after completion of the pre-vulcanization process, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is again added to 100 parts by weight of the silicone rubber compound KE5560U. In addition, it is added at a ratio of 0.5 part by weight, uniformly mixed using two rolls of a roll mixer, pressed at a temperature of 170 ° C. and a pressure of 9.8 MPa for 10 minutes, and then subjected to post-vulcanization. The sheet was 2 mm thick. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG.

(Comparative Example 3)
For comparison of physical properties, the same silicone rubber compound KE5560U (manufactured by Shin-Etsu Chemical Co., Ltd.) as in Examples 5 and 6 was used as an unvulcanized silicone rubber, and vulcanized under the conventional vulcanization conditions described in the manufacturer's catalog. The physical properties of the silicone rubber sheet are shown as Comparative Example 3 in FIG.

  The vulcanization conditions in Comparative Example 3 were C-8 (a vulcanizing agent containing 25% 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane with respect to 100 parts by weight of the silicone rubber compound KE5560U. 2 parts by weight of Shin-Etsu Chemical Co., Ltd.) was added and mixed uniformly using a two-roll roll mixer. Thereafter, pressing was performed at 170 ° C. and a pressure of 9.8 MPa for 10 minutes to prepare a 2 mm-thick silicone rubber sheet. Further, the prepared silicone rubber sheet was heated at 200 ° C. for 4 hours to be subjected to an aging treatment, and physical properties were measured in the same manner as in Examples 5 and 6. The results are shown in FIG.

  When Examples 5 and 6 in FIG. 4 are compared with Comparative Example 3, the tensile strength is slightly superior to Comparative Example 3 produced by the conventional method, but the tear strength (same as the tear strength) is It can be seen that Examples 5 and 6 to which the present invention is applied are improved by about 1.4 to 1.7 times, confirming the effectiveness of the present invention.

  In Example 7, a pre-vulcanization step was performed using silicone rubber compound SH75U (manufactured by Toray Dow Corning Silicone) as the unvulcanized silicone rubber. To 100 parts by weight of silicone rubber compound SH75U, 0.3 part by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane is added as a vulcanizing agent, and two rolls of a roll mixer are added. Mixed uniformly and heated at a temperature of 170 ° C. for 20 minutes.

  After cooling the partially vulcanized silicone rubber after completion of the pre-vulcanization process, again, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane as a vulcanizing agent is added to 100 parts by weight of the silicone rubber compound SH75U. 0.15 parts by weight with respect to the mixture, uniformly mixed using two rolls of a roll mixer, pressed for 10 minutes under conditions of a temperature of 170 ° C. and a pressure of 9.8 MPa, followed by post-vulcanization, A sheet having a thickness of 2 mm was prepared. Thereafter, an aging treatment was performed at a temperature of 200 ° C. for 4 hours. The physical properties of such a sheet are shown in FIG.

(Comparative Example 4)
For comparison of physical properties, the same silicone rubber compound SH75U as in Example 7 above was used as an unvulcanized silicone rubber, and vulcanized under the vulcanization conditions of the conventional method described in the manufacturer's catalog. 4 shows as Comparative Example 4.

  The vulcanization conditions in Comparative Example 4 were RC-4 (a vulcanizing agent containing 50% 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane with respect to 100 parts by weight of silicone rubber compound SH75U. 1.2 parts by weight of Toray Dow Corning Silicone Co.) was added and mixed uniformly using a two-roll roll mixer. Thereafter, pressing was performed at 170 ° C. and a pressure of 9.8 MPa for 10 minutes to prepare a 2 mm-thick silicone rubber sheet. Furthermore, the produced silicone rubber sheet was heated at a temperature of 200 ° C. for 4 hours for aging treatment. The physical properties of the sheet after the aging treatment were measured in the same manner as in Example 7, and the results are shown in FIG.

  When Example 7 and Comparative Example 4 in FIG. 4 are compared, both the tensile strength and tear strength (same as tear strength) are improved as compared with Comparative Example 4. In particular, the tear strength is about 1. It turns out that it has improved 5 times.

  From the above results, the effectiveness of the present invention is also confirmed from the above examples.

  The present invention can be effectively used in the field of techniques for improving the tear strength of silicone rubber.

It is a flowchart which shows the process sequence of the manufacturing method of the silicone rubber concerning this invention. It is a flowchart which shows the process procedure in the manufacturing method of the conventional silicone rubber. The vulcanization conditions of each example to which the present invention is applied are shown in a list. The physical property comparison between each example to which the present invention is applied and a comparative example of the conventional method is shown in a list.

Explanation of symbols

S100, S200, S210, S220, S230 step S300, S310, S320, S330, S400 step S510, S520, S530 step

Claims (6)

A pre-curing step in which a vulcanizing agent is added to the unvulcanized silicone rubber and partially vulcanized;
A method for producing silicone rubber, comprising a post-vulcanization step of adding a vulcanizing agent to the partially vulcanized silicone rubber obtained in the pre-vulcanization step and vulcanizing the rubber. In the manufacturing method of the silicone rubber of Claim 1,
The addition amount of the vulcanizing agent in the pre-vulcanization step is set to 0.001 part by weight or more and 1.0 part by weight or less with respect to 100 parts by weight of the unvulcanized silicone rubber. A method for producing silicone rubber. In the manufacturing method of the silicone rubber of Claim 1 or 2,
A method for producing a silicone rubber, wherein the unvulcanized silicone rubber is methylphenyl silicone rubber. In the manufacturing method of the silicone rubber of any one of Claims 1-3,
The method for producing silicone rubber, wherein the vulcanizing agent is a peroxide vulcanizing agent. In the manufacturing method of the silicone rubber of any one of Claims 1-4,
The method for producing silicone rubber, wherein the vulcanizing agent added in the pre-vulcanization step and the vulcanizing agent added in the post-vulcanization step are different vulcanizing agents. A silicone rubber composition obtained by vulcanizing an unvulcanized silicone rubber,
The said silicone rubber composition is manufactured by the manufacturing method of the silicone rubber of any one of Claims 1-5, The silicone rubber composition characterized by the above-mentioned.

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