JPH0580938B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a process oil containing insoluble sulfur for rubber, and more particularly to a process oil that can be impregnated with insoluble sulfur for rubber to suppress a decrease in the insolubilization rate of the sulfur over a long period of time. . [Problems to be solved by conventional techniques and inventions] In general, insoluble sulfur for rubber (Japan Rubber Association
SRIS 1102-1967) is impregnated with process oil for the purpose of safety during transportation (prevention of static electricity, etc.) and to improve workability during rubber kneading. By the way, insoluble sulfur is used when adhering two types of rubber with different compounding agents, or when adding rubber products where rubber products with different compositions are in contact, or when adding it to transparent rubber products or brightly colored rubber products. has been done. The purpose of this use is that since insoluble sulfur migrates or diffuses less in rubber products than other sulfurs, it can suppress blooming, scorch, overvulcanization, etc. of rubber products. However, this insoluble sulfur (which is thought to be mainly in the form of Sμ) is inherently unstable, and the insolubilization rate (carbon disulfide insoluble content) tends to decrease due to crystal transition. This poses a problem, which in turn affects the quality of the final rubber product. Furthermore, the insolubilization rate of the above-mentioned insoluble sulfur is affected by the temperature during storage, but it is also greatly influenced by the properties of the process oil that is impregnated. [Means for Solving the Problems] As a result of repeated research focusing on the correlation between the insolubilization rate of insoluble sulfur and the properties of process oil, the present inventors have found that the viscosity is within a certain range, and when a certain amount or more Among process oils containing sulfur, we found that those with a basic nitrogen content of 85 ppm or less are effective in suppressing the insolubilization rate of insoluble sulfur. The present invention was completed based on this knowledge. That is, the present invention has a viscosity of 5 to 40°C at 40°C.
150 cSt, a sulfur content of 0.1% by weight or more, and a basic nitrogen content of 85 ppm or less. As mentioned above, the process oil of the present invention has a viscosity at 40°C in the range of 5 to 150 cSt, preferably 10 to 150 cSt.
It is in the range of 50sSt. If the viscosity is less than 5 cSt, the sulfur will separate, which is a disadvantage.
If it exceeds 150 cSt, it is not preferable because it will not penetrate sulfur uniformly. Furthermore, the process oil of the present invention has a low sulfur content.
The amount used is 0.1% by weight or more, preferably 0.15 to 2.0% by weight. According to the research conducted by the present inventors, there is a tendency that the higher the sulfur content in the process oil, the more effective it is in suppressing the insolubilization rate of insoluble sulfur, but even if the sulfur content is 0.1% by weight or more, If the basic nitrogen content exceeds 85 ppm, the insolubilization rate of insoluble sulfur decreases rapidly. Therefore, the process oil of the present invention has a basic nitrogen content.
Must be below 85ppm, preferably
It is 75ppm or less. Here, the basic nitrogen content is
If it exceeds 85 ppm, there will be a disadvantage that the insolubilization rate of insoluble sulfur will be extremely reduced. In addition, there is no particular restriction on the total acid value of the process oil of the present invention, but it is generally 0.5mgKOH/g.
Below, preferably 0.2 mgKOH/g or less. For those whose total acid value exceeds 0.5mgKOH/g,
The insolubilization rate of insoluble sulfur tends to decrease, which causes some inconvenience in achieving the object of the present invention. As the process oil of the present invention, various mineral oils can be used as long as they have the above-mentioned properties, and there are no particular limitations. Specific examples of mineral oils that can be used as the process oil of the present invention include paraffinic crude oil, intermediate crude oil, naphthenic crude oil, and preferably naphthenic crude oil obtained by atmospheric distillation or residual oil from atmospheric distillation. Examples include refined oils obtained by refining distillate oils obtained by distilling them under normal pressure according to conventional methods. There are no particular restrictions on the purification method at this time, and various methods can be considered. Usually, (a) hydrogenation treatment, (b) solvent extraction treatment, (c) alkaline distillation or sulfuric acid washing treatment, and (d) clay treatment are carried out singly or in combination in an appropriate order. For example, the distillate oil is subjected to solvent extraction treatment, or the distillate oil is subjected to solvent extraction treatment and then hydrogenated, the distillate oil is subjected to sulfuric acid washing treatment, or the distillate oil is subjected to solvent extraction treatment and then sulfuric acid cleaning treatment. , or a method in which distillate is extracted with a solvent, then hydrogenated, and then washed with sulfuric acid; a distillate is extracted with a solvent and then treated with clay; or a distillate is extracted with a solvent, then hydrogenated, and then treated with clay. There is,
In addition, there is a method of appropriately mixing the treated oils obtained in these steps. Regardless of the method, the properties of the process oil obtained may be adjusted to have the above-mentioned viscosity, sulfur content, and basic nitrogen content. [Example] Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 7 and Comparative Examples 1 to 4 Mineral oils having the properties shown in Table 1 were used as sample oils, and the insolubilization rate of insoluble sulfur was measured in the following manner. That is, 1±0.1 g of insoluble sulfur is placed in a 100 ml glass container, and 20±1 g of the sample oil is placed in the container.
I put g. While stirring it in a solution at 100℃,
Heated for 1 hour. Immediately thereafter, the mixture was cooled with cold water at 5 to 10°C, and about 20 ml of carbon dioxide was added and stirred, and the solution was filtered through a 1G-4 glass filter.
The material captured by the filter was further washed with about 100 ml of carbon disulfide, dried at 60°C for 1 hour, and then weighed to determine the insolubilization rate of insoluble sulfur. The results are shown in Table 1.

【table】

〔Effect of the invention〕

As described above, by using the process oil of the present invention, it is possible to effectively suppress a decrease in the insolubilization rate of insoluble sulfur to be blended into rubber. Therefore,
The process oil of the present invention is capable of stabilizing insoluble sulfur, and as a result, makes it possible to produce high quality rubber products. Therefore, the process oil of the present invention can be used for tires,
It is widely and effectively used in industrial fields that manufacture various rubber products such as toys.

Claims (1)

[Claims] 1. An insoluble sulfur process oil for rubber, characterized by having a viscosity of 5 to 150 cSt at 40°C, a sulfur content of 0.1% by weight or more, and a basic nitrogen content of 85 ppm or less.