JPH0455388B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a conveyor belt for transporting oil sand that has excellent oil sand non-adhesion properties. (Prior art) Oil sands are petroleum resources that are abundantly deposited, especially in Canada and Venezuela. Among them, Canada's Athabasca oil sands account for about 1% of the world's oil reserves.
It is famous for having reserves of 3. Taking Athabasca oil sand as an example, it is formed by a thin film of water covering a fine silica sand flow, which is further surrounded by bitumen, and the water film also contains trace amounts of metals. ing. The oil sands generally contain 5 to 20% by weight of heavy viscous tar-like material, or bitumen, and are therefore commercially extracted as a petroleum resource. Collection methods include so-called open-pit mining, and a method in which unnecessary components such as bithyumen and silica sand are separated and collected underground, but in Athabasca, open-pit mining is carried out in which overburden from the oil sand is removed and the oil sand is directly collected. The collected oil sands are then transported to an extraction and purification plant by a conveyor belt. The conveyor belt that transports oil sands has
Conventionally, rubber belts made of a mixed rubber compound of natural rubber and styrene-butadiene rubber or acrylonitrile-butadiene rubber reinforced with steel cords have been used, but these conveyor belts are prone to oil sand adhesion and accumulation on their surfaces. This has the problem of not only contaminating the conveyor belt but also obstructing the conveyor belt from moving straight and reducing its carrying capacity. For this reason, kerosene,
Relatively inexpensive petroleum fractions such as light oil are sprayed onto the conveyor belt to prevent oil sand from adhering to the conveyor belt.
This is transported to an extraction and purification plant. However, this method uses flammable kerosene and diesel oil, which poses a risk of fire, accelerates the deterioration of the conveyor belt, and increases collection costs. Therefore, in recent years, instead of kerosene or diesel oil, water has been used as a non-stick liquid in the summer and an aqueous mixture of water, surfactant and antifreeze in the winter. Not only does antifreeze get mixed in with the oil sands, making separation of the oil sands extra expensive, but there is also the risk that the non-adherent liquid itself may freeze at temperatures as low as -50°C. In order to solve the above problems, Japanese Patent Application Laid-Open No. 58-198548 and No. 58-198550 have already published
Conveyor belts have been proposed that have a surface layer of non-adhesive vulcanized rubber made by vulcanizing a rubber composition mixed with a highly polar material, such as a glycol such as ethylene glycol or propylene glycol.
However, in order to obtain such non-adhesive vulcanized rubber, the conventional rubber processing method of kneading highly polar materials such as ethylene glycol and propylene glycol with rubber in an internal mixer does not allow for the uniform production of highly polar materials such as ethylene glycol or propylene glycol. The amount of material that can be incorporated into rubber is limited. For example, when using acrylonitrile-butadiene rubber with acrylonitrile content of 20% by weight as the rubber and ethylene glycol as the highly polar material, when kneading is carried out in an internal mixer, approximately 5% of the ethylene glycol is mixed with 100 parts by weight of the rubber. Parts by weight is the maximum blending amount in normal kneading operations, 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 anti-stick properties. (Objective of the Invention) As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a predetermined hydrophilic group-containing vinyl monomer is combined with a conjugated diene such as butadiene or isoprene and an α,β- A rubber compound containing a terpolymer obtained by copolymerization with an unsaturated nitrile has a highly polar surface after vulcanization.
The present invention was based on the discovery that a conveyor belt having extremely good oil sand adhesion resistance and having such vulcanized rubber as at least the surface layer is extremely suitable for conveying oil sand. be. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a conveyor belt for transporting oil sand which is excellent in non-adhesion of oil sand. (Structure of the Invention) The conveyor belt for conveying oil sand according to the present invention comprises (a) 55 to 95% by weight of conjugated diene component units, (b) 3 to 20% by weight of α,β-unsaturated nitrile, and (c) General Formula CH ₂ = CR ¹ COO-(CH ₂ CH ₂ O) _o -R ² (where, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group having 1 to 3 carbon atoms, and n is a number of 2 to 8 Hydrophilic group-containing vinyl monomer component unit 2 represented by
It is characterized by having at least the surface layer a vulcanized rubber obtained by vulcanizing a compound containing a terpolymer of ~25% by weight. Among the copolymer component units in the present invention, as the conjugated diene, for example, butadiene, isoprene, chloroprene, 1,3-pentadiene, hexadiene, etc. can be used, but α,β-unsaturated nitriles and hydrophilic Butadiene or isoprene is preferred from the viewpoint of ease of copolymerization with the group-containing monomer. As the α,β-unsaturated nitrile, acrylonitrile, methacrylonitrile, etc. can be used, and acrylonitrile is particularly preferred. The terpolymer in the present invention has the general formula CH ₂ =CR ¹ COO-(CH ₂ CH ₂ O) _o -R ² (wherein R ¹ is a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 3 carbon atoms, and n represents a number of 2 to 8.) Contains a vinyl monomer component containing a hydrophilic group. In the above general formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a methyl group, an ethyl group, or a propyl group. If R ² is a higher alkyl group equal to or higher than a butyl group, the resulting vulcanized rubber has poor affinity with water and also has reduced oil resistance, and is therefore not suitable for use in the present invention. Further, in the above general formula, n is a number from 2 to 8, preferably from 2 to 4. When n is 1, the resulting vulcanized rubber does not have good cold resistance and also has poor oil resistance. On the other hand, when n is 9 or more, the copolymerizability decreases, making it impossible to obtain the terpolymer used in the present invention. Examples of such hydrophilic group-containing vinyl monomers include ethyl carbitol acrylate, ethyl carbitol methacrylate, methyl carbitol acrylate, methyl carbitol methacrylate, methyl triglycol acrylate, methyl triglycol methacrylate, and acrylic acid. Examples include ethyl triglycol acid, ethyl triglycol methacrylate, methyltetraglycol acrylate, methyltetraglycol methacrylate, propyl triglycol acrylate, and ethylpentaglycol methacrylate. The above-mentioned hydrophilic group-containing vinyl monomer is composed of the corresponding acrylic acid or methacrylic acid,
For example, acrylic acid and 1/2 molar amount of diethylene glycol ethyl ether (carbitol) are mixed with an alkylene glycol alkyl ether using an acid catalyst such as p-toluenesulfonic acid under reflux. By reacting for 2 hours, ethyl carbitol acrylate can be easily obtained. In the present invention, in the terpolymer having the monomer component units as described above, 55 to 95% by weight of conjugated diene component units, 3 to 20% by weight of α,β-unsaturated nitrile, and hydrophilic group The vinyl monomer component unit content is 2 to 25% by weight. Preferably, conjugated diene component units 67 to 91% by weight, α,β-unsaturated nitrile 4 to 13% by weight, and hydrophilic group-containing vinyl monomer 5
~20% by weight. When the conjugated diene component unit is less than 55% by weight, the resulting vulcanized rubber has insufficient cold resistance and is unsuitable as a surface layer for oil sand conveyor belts that are often used in cold regions. On the other hand, when it exceeds 95% by weight, the oil resistance becomes poor and the affinity with water becomes poor. When the α,β-unsaturated nitrile component unit is less than 3% by weight, oil resistance is poor,
When the weight percentage is exceeded, the elasticity becomes inferior,
It is not preferable as a surface layer rubber for a conveyor belt, and has poor cold resistance, so it is also unsuitable as a surface layer for a conveyor belt for transporting oil sand. Furthermore, the hydrophilic group-containing vinyl monomer component unit is 3
In the original copolymer, it is 2 to 25% by weight, preferably 5 to 20% by weight. If it is less than 2% by weight, satisfactory polarity cannot be given to the vulcanized rubber, while if it exceeds 25% by weight, the elongation and strength will drop significantly, making it unsuitable for use in conveyor belts. do not have. In addition, the terpolymer described above has an intrinsic viscosity [η] (in tetrahydrofuran at 30°C)
is 1.0 to 4.0 dl/g, preferably 1.5 to 3.0 dl/g. When the intrinsic viscosity is less than 1.0dl/g,
This is because the solid retention property is poor and handling is difficult, and on the other hand, when it exceeds 4.0 dl/g, the processability is poor. The terpolymer as described above includes, for example, 55 to 95% by weight of a conjugated diene monomer, 3 to 20% by weight of an α,β-unsaturated nitrile monomer, and 2 to 20% by weight of the hydrophilic group-containing vinyl monomer. 25% by weight of the mixture in an aqueous medium;
Alternatively, it can be obtained by conventional radical copolymerization in an organic solvent. Examples of radical polymerization initiators include organic oxides such as benzoyl peroxide, cumene hydroperoxide, paramethane hydroperoxide, and lauroyl peroxide, bisazo compounds such as azobisisobutyl dinitrile, persulfates such as potassium persulfate, and organic A redox catalyst such as a combination of a compound and iron sulfate is used. A molecular weight regulator may also be used if necessary. As the molecular weight modifier, for example, t-dodecyl mercaptan, dialkylxanthogen disulfide, etc. are used. The copolymerization reaction is usually carried out at a temperature of 0 to 50 DEG C. in an oxygen-free atmosphere. The rubber compound in the present invention contains an appropriate vulcanizing agent together with the terpolymer. 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 terpolymer rubber, but for example, tetramethylthium disulfide, tetraethylthium disulfide, and the like are preferably used. These vulcanizing agents are 0.1 to 10 parts by weight per 100 parts by weight of the above terpolymer rubber,
Preferably it is blended in an amount of 1 to 5 parts by weight. Further, a vulcanization aid may be used in combination with the vulcanizing agent. Conventionally known vulcanization aids can be used as appropriate; for example, diphenylguanidine, di-orthotolylguanidine salt of dicatecolboric acid, 2-mercaptobenzothiazole, Dibenzothiazyl disulfide, N-
Cyclohexyl-2-benzothiazyl sulfenamide, tetramethylthiuram monosulfide, etc., and metal oxides such as zinc white, magnesium oxide, litharge, etc., and fatty acids such as stearic acid and oleic acid as vulcanization accelerators. , amines such as triethanolamine and diethanolamine, and other activators such as diethylene glycol and triallyl trimellitate. Furthermore, in the present invention, the rubber compound may contain various commonly used fillers in addition to the above. 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, plasticizers such as di(2-ethylhexyl) phthalate, di(2-ethylhexyl) adipate, dibutyl phthalate, tri(2-ethylhexyl) trimellitate, tricresyl phosphate, and paraffin-based processes are used. A softening agent such as oil or aromatic process oil can be used in combination. Furthermore,
Phenyl-α-naphthylamine, N,N'-diphenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-N'-isopropyl-p
- Antiaging agents such as phenylene diamine, 2-mercaptobenzimidazole, and nickel dibutyldithiocarbamate can be used. If necessary, scorch inhibitors, processing aids, etc. are also used in combination. In order to produce the rubber compound 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 performed at a temperature of 130 to 170 °C for 10 to 10 minutes.
This is done by applying pressure for 60 minutes. The conveyor belt according to the present invention has at least a surface layer of vulcanized rubber made by vulcanizing a rubber compound containing the above-mentioned terpolymer, and is replenished in the longitudinal direction with metal or organic fiber cords, canvas, etc. This conveyor belt not only has excellent non-stick properties against oil sand, but also has excellent oil resistance, flexibility, and low-temperature properties, so it exhibits excellent performance as a conveyor belt for transporting oil sand. FIG. 1 shows a cross-sectional view of an example of a conveyor belt.
are laminated and bonded, and a steel cord 4 as a core material is embedded within this cushion rubber. FIG. 2 shows a sectional view of another example of a conveyor belt, in which an intermediate rubber layer 5 is further laminated and bonded in order to strengthen the bond between the surface layers 1 and 2 and the cushion rubber 3. As the cushion rubber, natural rubber, isoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, or mixtures thereof are preferably used, and in particular, acrylonitrile-butadiene rubber having an acrylonitrile content in the range of 15 to 25% by weight is used.
Butadiene rubber is particularly preferably used because it has an excellent balance of cold resistance and oil resistance. The compounding agents such as vulcanizing agents and fillers in these cushion rubbers are well known in the art, but may be the same as in the case of the terpolymer rubber according to the present invention. (Effects of the Invention) As described above, in the coil conveyor belt for oil sands according to the present invention, the hydrophilic group-containing vinyl monomer described above is replaced with an α,β-unsaturated nitrile-conjugated diene copolymer, typically , acrylonitrile-
Containing the butadiene copolymer as a copolymer component unit imparts high polarity to the vulcanized rubber itself, so conveyor belts with such vulcanized rubber in the surface layer have high polarity on the surface and oil When the sand is transported, oil sand is not substantially attached. Further, the belt can be transported from the collection point to the extraction and purification plant without spraying kerosene or water on the surface of the belt as in the past, and without substantially adhering oil sand to the belt surface. Furthermore, even when spraying an aqueous non-adhesive liquid containing water or antifreeze on the conveyor belt surface, the surface layer is highly polar, so a water film is formed on the belt surface, resulting in non-adhesive liquid every time oil sand is loaded. There is no need to spray the adhering liquid, and the number of times of spraying and consumption of the non-adhering liquid can be significantly reduced. Of course, since the conveyor belt of the present invention has excellent oil resistance, if necessary, kerosene or the like may be sprinkled on its surface without any problem. Therefore, according to the conveyor belt of the present invention, the cost of unnecessary non-adhesive liquid can be saved, and deterioration of the conveyor belt due to non-adherent liquid is less likely to occur.
Extra refining operations for collected oil sand due to contamination with water etc. are omitted, and costs for collection and refining 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 compound and vulcanized rubber) 100 parts of a terpolymer consisting of the component units shown in the table,
After mixing 55 parts of carbon black (N-330HAF), 5 parts of zinc oxide, 1 part of stearic acid, and 3 parts of anti-aging agent in an internal mixer, 2 parts of ions and 1.5 parts of vulcanization accelerator were mixed in an open roll. Mix the
A rubber mixture was prepared. Next, each rubber compound
After sensitive vulcanization at 150°C for 30 minutes, its physical properties were measured.
The results are shown in the table. For comparison, commercially available acrylonitrile-butadiene rubber (manufactured by Japan Synthetic Rubber Co., Ltd.) was used as a rubber.
A rubber compound was prepared in the same manner as above except that N250S, bound acrylonitrile amount 20% by weight, butadiene 80% by weight) was used, and after vulcanization at 150°C for 30 minutes, its physical properties were measured. The results are shown in the table. (Oil sand adhesion test on rubber sheets) Regarding the vulcanized rubber sheets of Examples 1 to 15 obtained by vulcanizing the rubber compound according to the present invention and the sheet of Comparative Example 1 (thickness: 2 mm, width: 20 cm, length: 30 cm) The following oil sand adhesion test was conducted. A first belt conveyor with a machine length of 9 m, a second belt conveyor with a machine length of 9 m, and a third belt conveyor with a machine length of 4 m are arranged in a U-shape, and from the first to the second belt conveyor,
The test equipment was constructed so that the oil sand could be transported sequentially from the second to the third, and the second
Each of the above vulcanized rubber sheets was adhered onto a belt conveyor using an adhesive. At an ambient temperature of 20-25°C, a hopper is installed on the end of the first belt conveyor, and Canadian oil sands are fed from this hopper onto the end of the first belt conveyor at a rate of 4 kg/min. The belt conveyor was run for 20 minutes at a speed of 40 m/min.
In this way, each belt conveyor

【table】

[Table] After transporting 80 kg of oil sand, the central part of the vulcanized rubber sheet (area
The oil sand adhering to the surface (10 x 10 cm) was scraped off with a spatula, and the weight was measured as the amount of oil sand adhering. The results are shown in the table. As is clear from the table, only a small amount of oil sand adhered to the vulcanized rubber sheet obtained by vulcanizing the tertiary copolymer rubber compound according to the present invention, whereas the conventional rubber compound (comparison) A large amount of oil sand adhered to the rubber sheet according to Example 1).

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing examples of conveyor belts. 1 and 2... surface layer, 3... cushion rubber,
4... Heartwood, 5... Intermediate rubber layer.

Claims (1)

[Scope of Claims] 1 (a) 55 to 95% by weight of conjugated diene component units, (b) 3 to 20% by weight of α,β-unsaturated nitrile, and (c) General formula CH ₂ =CR ¹ COO-( Hydrophilic group represented by CH ₂ CH ₂ O) _o −R ² (wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group having 1 to 3 carbon atoms, and n is a number of 2 to 8) Containing vinyl monomer component unit 2
1. A conveyor belt for oil sands, characterized in that it has at least a surface layer of vulcanized rubber obtained by vulcanizing a compound containing a terpolymer consisting of ~25% by weight. 2. The conveyor belt for transporting oil sands according to claim 1, wherein the conjugated diene is butadiene or isoprene, and the α,β-unsaturated nitrile is acrylonitrile. 3. The conveyor belt for oil sand transport according to claim 1, wherein the hydrophilic group-containing vinyl monomer component unit is ethyl carbitol acrylate. 4. The conveyor belt for oil sand transport according to claim 1, wherein the hydrophilic group-containing vinyl monomer component unit is methyl triglycol acrylate.