JPS61152748A - Rubber composition - Google Patents

Abstract

PURPOSE:A rubber composition that is obtained by adding a liquid polyhydric alcohol as a high-polar material and a hydropyilic polymer, thus giving vulcanized rubber which is suitable for use in conveyor belts for oil sand because of its high nontackiness. CONSTITUTION:100pts.wt. of natural rubber and/or synthetic rubber such as isoprene rubber, styrene/butadiene rubber are kneaded together with (A) 10-50 pts.wt., preferably 10-30pts.wt. of liquid polyhydric alcohol such as ethylene glycol and (B) 10-50pts.wt., preferably 10-30pts.wt. of a hydrophilic polymer of less than 50mu particle sizes such as polyvinyl pyrrolidone, polyethylene oxide and vulcanized at 130-170 deg.C for 10-60min under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a rubber composition, and more particularly to a rubber composition forming a non-tacky vulcanized rubber, and at least a surface treatment made of a vulcanized rubber comprising such a rubber composition. layer, and therefore, in particular,
The present invention relates to a conveyor belt that can be suitably used to convey highly adhesive substances such as oil sand.

(Prior Art) Oil sands are a petroleum resource that is particularly abundant in Canada and Venezuela, and Canada's Athabas oil sands are particularly famous because they have about 1/3 of the world's reserves. Take the Athabas force oil sands as an example.
This is formed by a thin water film covering fine silica sand grains, which is further surrounded by bitumen, and the water film also contains trace amounts of metals. This oil sand is generally a viscous tar-like substance with a weight of 5 to 20%,
That is, since it contains bitumen, it is also collected commercially as a petroleum resource. Collection methods include so-called open pit mining,
There is a method of separating and collecting unnecessary components such as bitumen and silica sand underground, but at Athapas, open-pit mining is carried out in which the overhang of the oil sand is removed and the oil sand is directly collected. The extracted oil sands are then transported by belt to an extraction and refining plant.

Conventionally, rubber belts made of mixed rubber compounds of natural rubber and styrene-butadiene rubber or acrylonitrile-butadiene rubber reinforced with steel cords have been used to transport oil sand, but oil sand adheres and accumulates. This not only contaminates the belt, but also prevents the belt from moving straight, reducing its carrying capacity. For this reason, conventionally,
As a non-adhesive liquid, relatively low-grade petroleum fractions such as dissolved oil and light oil are sprinkled onto the belt and transported to the extraction and refining plant while preventing oil sand from adhering.

However, this method uses flammable molten oil or light oil, which poses a risk of fire, accelerates the deterioration of the conveyor belt, and increases collection costs. Therefore, in recent years, instead of using soluble oil or diesel oil, water is used in the summer.
In winter, an aqueous mixture of water, surfactant, and antifreeze is used as a non-stick liquid, but the antifreeze mixes with the oil sands, requiring extra cost to separate the oil sands. Furthermore, at temperatures as low as -50°C, there is a risk that the non-adherent liquid itself may freeze.

In order to solve the above-mentioned problems, Japanese Patent Application Laid-open No. 58
-198548 and JP-A-58-198550, a rubber composition made by mixing a highly polar material, for example, glycol such as ethylene glycol or propylene glycol, is vulcanized, and the rubber itself has non-stick properties against oil sand. It is proposed that the However, when preparing such a rubber composition, the conventional rubber processing method of kneading highly polar materials such as ethylene glycol or propylene glycol with rubber in an internal mixer does not allow for uniform mixing of these highly polar materials. The amount that can be blended into rubber is limited. For example, as a rubber, the acrylonitrile content is 20%
When kneading with an internal mixer using ethylene glycol as a highly polar material, based on 100 parts by weight of rubber,
Approximately 5 parts by weight of ethylene glycol is the maximum amount to be blended in a normal kneading operation, and if this is exceeded, the rubber will slip on the roll surface during kneading processing using an internal mixer or open rolls. However, with this level of ethylene glycol content, the vulcanized rubber may still not have sufficient non-stick properties.

(Purpose of the Invention) As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by blending a hydrophilic polymer into rubber at the same time as a highly polar material such as a polyhydric alcohol, the The stable presence of the polyhydric alcohol facilitates the kneading of the rubber composition, thus allowing the inclusion of a sufficient amount of highly polar material to impart satisfactory non-stick properties to the rubber after vulcanization. This heading led to the present invention.

That is, the present invention provides a rubber composition that generally provides a non-tacky vulcanized rubber, and has a surface layer made of the vulcanized rubber of this rubber composition, and substantially removes the oil sand described above. It is an object of the present invention to provide a conveyor belt that can be transported without adhering to objects.

(Structure of the Invention) The rubber composition according to the present invention contains 100 parts by weight of natural rubber and/or synthetic rubber, 10 to 50 parts by weight of liquid polyhydric alcohol, and 10 to 50 parts by weight of hydrophilic polymer. Features.

Rubbers preferably used in the present invention include natural rubber,
and synthetic rubbers such as isoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and chloroprene rubber. Among natural rubber and the above synthetic rubbers, isoprene rubber,
It is at least one selected from styrene-butadiene rubber and acrylonitrile-butadiene rubber. These rubbers can be used alone or in a mixture of two or more. For example, butadiene rubber, butadiene rubber,
Chloroprene rubber etc. are mixed.

In the present invention, a liquid polyhydric alcohol having a plurality of hydroxyl groups is used as a highly polar material that imparts non-adhesive properties to vulcanized rubber. Liquid polyhydric alcohols include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, and hexylene glycol, as well as glycerin, trimethylolpropane, hexanetriol, and pentyl alcohol. Preferred specific examples include trihydric or higher polyhydric alcohols such as erythritol, but especially low molecular weight, low viscosity liquids such as ethylene glycol and propylene glycol, and at normal rubber vulcanization temperatures. Polyhydric alcohols that do not easily evaporate at temperatures of 140 to 160°C are preferred.

In the present invention, a hydrophilic polymer is blended into the rubber composition so that the polyhydric alcohol stably exists in the rubber composition and can be uniformly kneaded with the rubber. Hydrophilic polymers used include polyvinylpyrrolidone, polyethylene oxide, polyvinyl alcohol, methylcellulose, carboxylated methylcellulose, cellulose powder, starch, and copolymers of polyvinyl alcohol and cyclic acid anhydrides such as maleic anhydride or phthalic anhydride. , a saponified block copolymer of vinyl acetate and acrylic acid ester, and a copolymer of acrylic acid and a polyfunctional monomer. The hydrophilic polymers used in the present invention include those listed above. Without limitation, resins such as starch-acrylic copolymers and acrylic acid-vinyl alcohol copolymers, which are commercially available as so-called superabsorbent resins, can also be suitably used. Furthermore, the hydrophilic polymer used in the present invention preferably has a particle size of 50 μm or less. This is because when the particle size increases, the rubber surface becomes so-called shark-skinned and the mechanical strength of the rubber decreases.

In the present invention, the rubber composition is a rubber 10 as described above.
The liquid polyhydric alcohol contains 10 to 50 parts by weight, preferably 10 to 30 parts by weight, and the hydrophilic polymer contains 10 to 50 parts by weight, preferably 10 to 30 parts by weight. When the amount of liquid polyhydric alcohol blended is less than 10 parts by weight per 100 parts by weight of rubber, the vulcanized rubber has sufficient surface non-adhesion, while when it exceeds 50 parts by weight, it becomes uniform with the rubber. This is not preferred because it makes kneading difficult. Regarding hydrophilic polymers, when the amount is more than 50 parts by weight per 100 parts by weight of rubber, the mechanical strength of the vulcanized rubber decreases significantly, and when it is less than 10 parts by weight, the rubber composition This is because it becomes difficult for the polyhydric alcohol to exist stably inside.

The rubber composition according to the present invention contains an appropriate vulcanizing agent depending on the rubber used. As rubber, natural rubber, isoprene rubber, styrene-butadiene rubber, acrylonitrile-
When using butadiene rubber or butadiene rubber, etc.
Sulfur and/or sulfur-containing compounds are usually blended as the vulcanizing agent.

Any sulfur-containing compound may be used as long as it can vulcanize the rubber, but for example, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and the like are preferably used.

These vulcanizing agents are added in an amount of 0.1 to IO parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the rubber mixture. Further, a vulcanization aid may be used in combination with the vulcanizing agent.

As the vulcanization aid, those conventionally known for the above-mentioned rubbers can be used as appropriate. For example, as the vulcanization accelerator, diphenylguanidine, di-orthotolylguanidine salt of dicatechol oxalic acid, 2-mercaptobenzothiazole , dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl sulfenamide, tetramethylthiuram monosulfide, etc., and metal oxides such as zinc white, magnesium oxide, litharge, etc. as vulcanization accelerating aids, Examples include fatty acids such as stearic acid and oleic acid, amines such as triethanolamine and jetanolamine, and other activators such as diethylene glycol and triallyl trimellitate.

Further, when chloroprene rubber is used as the synthetic rubber, zinc oxide, magnesium oxide, etc. are used as a vulcanizing agent, and if necessary, an appropriate vulcanization accelerator is used in combination.

Further, the rubber composition according to the present invention may contain various fillers commonly used in the above-mentioned rubbers in addition to the above-mentioned fillers.

For example, fillers include white carbon, carbon black, silica, calcium carbonate, clay, magnesium carbonate, diatomaceous earth, various silicates, and organic fillers. When blending these fillers,
Di(2-ethylhexyl) phthalate, di(2-ethylhexyl) adipate, dibutyl phthalate, tri(
Plasticizers such as 2-ethylhexyl) trimellitate and tricresyl phosphate, and softeners such as paraffinic process oils and aromatic process oils can be used in combination. Furthermore, phenyl-α-naphthylamine, N, N
'-Diphenyl-p-phenylenediamine, 6-nitoxy2.2.4-trimethyl-1,2-dihydroquinoline, N-phenyl-N'-isopropyl-p-phenylenediamine, 2-mercaptobenzimidazole, dibutyldithiocarbamic acid Anti-aging agents such as nickel can also be used. In addition, if necessary, scorch inhibitor,
Processing aids and the like are also used.

In order to produce the rubber composition according to the present invention, the above components are usually kneaded using a Banbury mixer, a kneader mixer, a roll, or the like. In addition, vulcanization of rubber compositions is usually
This is carried out by applying pressure at a temperature of 130 to 170°C for 10 to 60 minutes.

The vulcanized rubber thus obtained has excellent non-adhesion to bitumen and can therefore be suitably used as a surface layer for a conveyor belt for conveying oil sand containing bitumen.

Therefore, the conveyor belt according to the invention comprises 100 parts by weight of natural rubber and/or synthetic rubber and 1 part by weight of liquid polyhydric alcohol.
It is characterized in that at least its surface layer comprises a vulcanized rubber obtained by vulcanizing a rubber compound containing 0 to 50 parts by weight of a hydrophilic polymer and 10 to 50 parts by weight of a hydrophilic polymer.

As the rubber for conveyor belts, at least one selected from natural rubber, isoprene rubber, styrene-butadiene rubber, and acrylonitrile-butadiene rubber is preferable, but acrylonitrile-butadiene rubber with an acrylonitrile content in the range of 15 to 25% by weight has excellent cold resistance. It is particularly preferably used because it has an excellent balance of oil resistance. The compounding agents such as the vulcanizing agent and filler are as described above. It goes without saying that the above rubber compound may contain other rubbers such as butadiene rubber and chloroprene rubber, vulcanizing agents, vulcanization accelerators, and other fillers.

Conveyor belts that have at least a surface layer of vulcanized rubber obtained by vulcanizing a rubber composition containing these, and are reinforced in the longitudinal direction with metal, organic fiber cord, canvas, etc., are resistant to oil sand. Not only does it have excellent non-stick properties, but it also has excellent oil resistance, flexibility, and low-temperature properties.
Suitable for use as a conveyor belt for oil sand transport 11.

(Effects of the Invention) As described above, the rubber composition according to the present invention stably and uniformly blends polyhydric alcohol as a highly polar material into unruly sulfur rubber by using a hydrophilic polymer. Therefore, the vulcanized rubber obtained by vulcanizing this has remarkable non-adhesion even to highly adhesive substances such as oil sand because the vulcanized rubber itself is highly polarized. .

Therefore, according to a conveyor belt having at least a surface layer of vulcanized rubber formed by vulcanizing the rubber composition of the present invention, it is possible to use oil without spraying molten oil or water on the belt surface as in the past. The sand can be transported from the point of collection to the extraction and purification plant with the sand substantially free from adhesion to its surface.

In addition, even when spraying an aqueous non-stick liquid containing water or antifreeze on the conveyor belt surface, a water film is formed on the belt surface due to the high polarity of the surface layer. There is no need to spray the liquid, and the number of times of spraying and consumption of the non-adherent liquid can be significantly reduced. Of course, since the conveyor heald of the present invention has excellent oil resistance, there is no problem in spraying melted oil or the like on its surface if necessary.

Therefore, according to the conveyor held of the present invention, the cost of unnecessary non-adherent liquid can be saved, the deterioration of the conveyor held due to non-adherent liquid is less likely to occur, and extra purification operations due to contamination with water etc. can be omitted, and the collection and refining costs can be reduced. Furthermore, since there is no need to use a flammable non-adhesive liquid such as light oil, the risk of fire or the like caused by it is also eliminated.

(Examples) Examples of the present invention are listed below, but the present invention is not limited to these Examples. Note that in the following, parts indicate parts by weight.

Examples (Preparation of rubber composition and rubber sheet) Rubbers shown in Tables 1 and 2 alone or as a mixture 100
55 parts of carbon black (N-330HAF), 5 parts of zinc oxide, 1 part of stearic acid, 3 parts of anti-aging agent, and the liquid polyhydric alcohol and hydrophilic polymer shown in the table were mixed in a closed system at the ratio shown in the table. After mixing in a machine, 2 parts of sulfur and 1.5 parts of a vulcanization accelerator were further mixed in an open roll.
A rubber composition was prepared. The hydrophilic polymers blended in Examples 1 to 19 all have an average particle size of 50 μm or less. Next, each rubber composition was
0CII+, after forming into a rubber sheet with a length of 30 mm, 1
It was vulcanized at 50° C. for 40 minutes and subjected to an oil sand adhesion test.

For comparison, a rubber composition containing no liquid polyhydric alcohol and a hydrophilic polymer (Comparative Example 1), a rubber composition containing no hydrophilic polymer (Comparative Example 2), and a rubber composition with an average particle size of 8.
A rubber composition containing a hydrophilic polymer of 70μ or less (Comparative Example 3) and a hydrophilic polymer of 300μ or less (Comparative Example 4), and a rubber sheet made of the composition for Comparative Example 1 were prepared in the same manner as above. Obtained.

The rubber compositions according to the present invention (Examples 1 to 19) were easy to knead and had good processability into sheets. On the other hand, in the composition of Comparative Example 2 in which no hydrophilic polymer was blended, ethylene glycol bled onto the surface of the rubber during kneading, causing slippage between the rubber and the rolls, and the composition could not be processed into a rubber sheet. In addition, in Comparative Examples 3 and 4 containing a hydrophilic polymer having an average particle size larger than 50μ, unevenness occurred in the sheet prepared from the composition, so it could not be subjected to the oil sand adhesion test.

(Oil sand adhesion test on rubber sheet) No. 1 with a aircraft length of 9 m
A belt conveyor with a machine length of 9 m, a second belt conveyor with a machine length of 4 m, and a third belt conveyor with a machine length of 4 m are arranged in a U-shape,
The test apparatus was configured so that the oil sand could be conveyed sequentially from the first to the second and from the second to the third, and each vulcanized rubber sheet obtained above was placed on a second belt conveyor located in the center. were attached with adhesive.

At an ambient temperature of 20-25° C., a hopper is installed on the end of the first belt conveyor, and 4 k of Canadian oil sands is poured from this hopper onto the end of the first belt conveyor.
g/min, and each belt conveyor was run for 20 minutes at a speed of 40 m/min. After 80 kg of oil sand is transported by each belt conveyor in this way, the oil sand adhering to the center part (area 10 x lOcm) of the vulcanized rubber sheet on the second belt conveyor is scraped off with a spatula, and the weight is removed from the oil sand. It was measured as the amount of adhesion. The results are shown in Tables 1 and 2.

As is clear from the table, only a small amount of oil sand adhered to the rubber sheet made of the vulcanized rubber of the rubber composition of the present invention, but a large amount of oil sand adhered to the rubber sheet made of the conventional composition (Comparative Example 1). oil sands were attached.

Claims (4)

[Claims] (1) A rubber composition characterized by containing 100 parts by weight of natural rubber and/or synthetic rubber, 10 to 50 parts by weight of liquid polyhydric alcohol, and 10 to 50 parts by weight of a hydrophilic polymer. (2) The rubber composition according to claim 1, wherein the hydrophilic polymer has a particle size of 50 μm or less. (3) Vulcanized rubber obtained by vulcanizing a rubber compound containing 100 parts by weight of natural rubber and/or synthetic rubber, 10 to 50 parts by weight of liquid polyhydric alcohol, and 10 to 50 parts by weight of hydrophilic polymer. A conveyor belt for conveying oil sand, characterized in that it has at least its surface layer. (4) The conveyor belt for transporting oil sand according to claim 3, wherein the hydrophilic polymer has a particle size of 50 μm or less.