JPS6252108A - Granular sulfur for vulcanization of rubber - Google Patents

Abstract

PURPOSE:To improve the dispersibility and fluidity of sulfur and suppress the dusting tendency and the blocking of sulfur during storage, by adding a specific amount of ethylene glycol to powdery sulfur and mixing and granulating the mixture. CONSTITUTION:Powdery sulfur is mixed with 0.1-50wt% one or more compounds selected from ethylene glycol, diethylene glycol and triethylene glycol. The particle size of the powdery sulfur is preferably finer than about 150 mesh. The mixture is granulated to obtain granular sulfur for the vulcanization of rubber. The granular sulfur produced by this process has excellent antistaticity. Since the composition is free from mineral oil, it can be granulated without using a high-speed mixer. Furthermore the blocking of the sulfur during storage can be prevented without using a drying treatment.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to granulated sulfur for use in rubber vulcanization.

[Prior Art] As the sulfur for rubber vulcanization, powdered sulfur having particles of 1 and X particles finer than 150 mesh is usually used in consideration of dispersibility in the rubber. However, powdered sulfur easily turns into dust, which not only has an adverse effect on the human body, but also poses the risk of causing a dust explosion.Also, it is often charged with static electricity and aggregates, causing problems in work. Conventionally, inorganic substances such as zinc oxide have been added to prevent agglomeration, and mineral oil has been added to powdered sulfur to suppress dust generation.

However, those containing only inorganic substances are insufficient in preventing dust formation, and those containing only mineral oil have poor fluidity and turn into dust when pressurized. Therefore, there was a problem that it was difficult to handle. In addition, in recent years, granular sulfur with good fluidity has become required for process automation, so mineral oil and surfactants are added to powdered sulfur.
A method for obtaining granular sulfur (Japanese Unexamined Patent Publication No. 49-93294) has also been proposed. However, adding mineral oil to powdered sulfur requires a high-speed mixer, and if a sufficient drying process is not performed, the pressure applied during storage etc. will cause the mineral oil to form into blocks. Furthermore, since the surfactant used has little experience of being used in rubber, it cannot be said that there is no risk of damaging the physical properties of rubber.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a product that has excellent dispersibility, no dust generation, and fluidity, is easy to manufacture, and is easy to store. The object of the present invention is to provide granular sulfur that is free from the risk of forming blocks in the interior.

[Means for Solving the Problems] In order to achieve the above object, the feature of the present invention is to use at least one of ethylene glycol, diethylene glycol, and triethylene glycol as an additive in a weight ratio of 0 to powdered sulfur. .1-50%, preferably 0.5
It consists in adding ~25%. The powdered sulfur to which the above additives have been added is mixed in a mixer. The mixer may be a rotary type or an agitating type, and does not need to be particularly high speed. By mixing, the above-mentioned additive acts as a binder, binds and granulates a plurality of fine sulfur particles, and produces so-called granular sulfur having a particle size of 0.05 mm or more. This granular sulfur is left as is.
Or lightly dry it and use it as sulfur for vulcanization.

[Function] The granulated sulfur produced by the granulating action of ethylene glycol or the like of the present invention has small variations in particle size.

Since no particularly excessive amount is produced, the dispersibility during rubber vulcanization is good. Ethylene glycol and the like contained in the granules have hygroscopic properties and prevent the granules from becoming electrically charged. Since the granules have a diameter of 0.05 mm or more, they do not generate dust, and there is no risk of them breaking into dust, worsening sanitary conditions, or exploding.

[Example] The granular sulfur of the present invention will be explained based on Examples.

Adding 16% by weight commercially available ethylene glycol and diethylene glycol to 200 mesh of powdered sulfur,
Two types of granulated sulfur containing ethylene glycol and diethylene glycol were granulated by stirring and mixing in a stirring type mixing granulator, each equipped with a stirring blade.

The particle size distribution of the obtained granular sulfur is shown in Table 1 in comparison with untreated powdered sulfur.

From Table 1, it can be seen that the sulfur granules of the present invention have a diameter of 0°05 mm.
Since 90% of them are distributed between 0.05 mm and 1 mm, it is clear that unlike powdered sulfur with a particle size of 0.05 mm or less, it has excellent dispersibility and non-dusting properties. .

Next, we took up the angle of repose as an indicator of liquidity. As shown in Figure 1, a 75mmφ JIS sieve (2,000
,) A metal frame with a height of 80 mm is added to the top and a glass funnel is attached to the bottom, which is attached to a vibrator, the sample is placed on the sieve, the sample is vibrated and passed through the mesh, and the sample passes through the glass funnel and downwards. The angle of repose θ formed by dropping the sample onto a metal circular tray-shaped platform with a diameter of 80 mm and an edge height of 10 mm was measured.

Untreated powdered sulfur has a strong electrostatic charge, and the particles repel each other and do not form an angle of repose, or even if they do, they do not form a neat shape as shown in Figure 2, and the tip does not form as shown in Figure 3. Since the shape is sharp, the side surface indicated by the broken line in the figure was measured as a stable surface. On the other hand, both the ethylene glycol-treated granular sulfur and the diethylene glycol-treated granular sulfur formed a clear angle of repose as shown in FIG. The measured values shown in Table 2 are all averages of five test values.

Additionally, the following test was conducted as a measure of fluidity.

about 2 each of untreated powdered sulfur, ethylene glycol treated granulated sulfur and diethylene glycol treated granulated sulfur.
ml was placed in a 10 ml graduated cylinder with an inner diameter of 10 mm, and the cylinder was inverted by placing paper on the mouth of the cylinder, and then the cylinder was lifted about 20 mm to discharge the contents onto the paper. Untreated powdered sulfur is
Even when the cylinder was turned upside down, it remained stuck to the bottom and did not move downward, and after several light impacts, it fell into the mouth of the cylinder. Then, even when the cylinder was lifted and the mouth part was removed from the page, the end of the tube remained closed, and the cylinder did not fall to the page and create a deposit unless it was subjected to several more impacts. The resulting deposit was a standing structure with a portion remaining inside the pipe without changing its shape. On the other hand, both the ethylene glycol-treated granular sulfur and the diethylene glycol-treated granular sulfur not only immediately flowed downward when the cylinder was inverted, but also flowed out and deposited on the paper as the cylinder was lifted and the end of the tube was moved away from the paper. The shape of the deposit was lower and gentler than that of untreated powdered sulfur. The state of each deposition is shown in FIGS. 4 to 6. As described above, since the granular sulfur of the present invention has a small angle of repose, it has good fluidity and can be automated by air transportation or the like. Although it has not been specifically tested, it is thought that it has an antistatic effect because it contains ethylene glycol, etc., and that there is no aggregation due to charging. Further, granular sulfur having a particle size of 0.2 mm or more is extremely easy to handle, and it is possible to automate processes such as air transportation.

Furthermore, since the vulcanized sulfur of the present invention does not contain any mineral oil, it can be used without drying after mixing and granulation, and even when stored in paper bags for a long period of time, it can be easily packed into one bag. If dried, there is no risk of block formation during storage.

Although no examples are shown, similar granular sulfur can be obtained by adding triethylene glycol, which has properties similar to ethylene glycol and diethylene glycol, either alone or in combination with the former two.

Next, the physical properties of the rubber vulcanized with the granulated sulfur of the present invention were measured.

Rubber with the composition shown in Table 3 was rolled into 6-inch rolls for 15 minutes.
The resulting unvulcanized rubber was vulcanized at 160° C. for 15 minutes. Three physical properties of vulcanized rubber, J I
The results measured according to the 3 tensile tests of the 5K6301 vulcanized rubber physical test method are shown in Table 4 together with comparative examples using untreated powdered sulfur. Rubbers using ethylene glycol-treated sulfur granules and sulfur granules treated with diethylene glycol have less variation in various physical properties and can have a uniform quality.

"Effects of the Invention" - As stated, the granulated sulfur of the present invention has excellent dispersibility, non-dusting properties, fluidity, and antistatic properties, but it is different from conventional ones containing mineral oil and surfactants. Unlike this product, it does not contain any mineral oil, so it can be granulated without using a high-speed mixer, and there is no risk of it forming into blocks during storage, even if it does not undergo a sufficient drying process before being packed into bags. It has this excellent effect.

Further, ethylene glycol, diethylene glycol, etc. used in the present invention are relatively inexpensive and have been used in rubber, so there is no risk of adversely affecting the physical properties of rubber.

[Margin below] Table 3

[Brief explanation of drawings]

Figures 1 to 3 illustrate the fluidity of powder particles, Figure 4 shows the deposition status of conventional powdered sulfur, and Figures 5 and 6 show the deposition status of granular sulfur according to the present invention. It's a photo.

Claims (1)

[Scope of Claims] 1) Additives consisting of one type or a combination of two or more types of ethylene glycol, diethylene glycol, and triethylene glycol are added and mixed to powdered sulfur in an amount of 0.1 to 50% by weight and granulated. Granular sulfur for rubber vulcanization characterized by the fact that it has been produced. 2) Granular sulfur for rubber vulcanization according to claim 1, characterized in that 0.5 to 25% by weight of additives are added to the powdered sulfur. 3) Granular sulfur for rubber vulcanization according to claim 1 or 2, wherein the powdered sulfur has a mesh size of 150 mesh or more.