JP2000016546A - Cloth layer conveyor rubber belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cloth layer conveyor rubber belt furnished with cover rubber to restrain swelling against an aromatic resistance oily, especially coal tar and its fractionated substance. SOLUTION: Rubber ((weight after soaking)-(weight before soakin)/ (density of indan or 1,2,3,4-tetrahydronaphthalene)/(volume before soaking)) of which becomes less than 1 even when it is soaked in indan or 1,2,3,4- tetrahydronaphthalene for more than two hours is made cover rubber, or rubber or synthetic high polymer ((weight after soaking)/(weight before soaking)-1)/((density of indan or 1,2,3,4-tetrahydronaphthalene)/(volume before soaking) of which becomes less than 1 even when it is soaked in indan or 1,2,3,4- tetrahydronaphthalene for more than two houesis applied, impregnated or adhered by more than 0.1 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyor rubber belt provided with a cover rubber using a single-layer or multi-layer fabric core, and is suitable for transferring solids including coal tar and fractions of coal tar. Conveyor rubber belt.

[0002]

2. Description of the Related Art A conveyor rubber belt with a cover rubber is composed of a fabric core and a cover rubber, and the fabric core uses natural fibers and chemical fibers alone or in combination. Natural rubber and synthetic rubber are used for the cover rubber, and a compounding agent and the like are added to these rubbers. There are a wide variety of synthetic rubbers such as silicone rubber, butyl rubber, polybutadiene, neoprene, chlorinated rubber, butadiene / styrene, but generally, butadiene / acrylonitrile, and ethylene / propylene copolymer as a heat resistant belt. Used.

Conveyor rubber belts have strength, elongation, hardness,
Although they are classified according to wear resistance and the like, they are used properly depending on the application, selection of the material of the cover rubber is also very important. Unvulcanized rubber dissolves in a solvent, but vulcanized rubber swells when immersed in a solvent because it has a three-dimensional network structure. When the cover rubber swells in the state of the conveyor belt, the strength and hardness of the belt are reduced, and the wear resistance is deteriorated. In addition, the belt may be meandered or slack due to deformation, and may not be used. Actually, the strength before use is 180kgf / c
m, conveyor belt with hardness of 59 °, 3w of coal tar
After transporting the coal powder with t% added, it dropped to 99 kgf / cm, 37 °, and in some cases, it became unusable due to warpage.

[0004] The swelling of rubber is affected by the number of network chains (degree of crosslinking), the molecular size of the solvent, the affinity between the rubber and the solvent, and the like.
When a filler or a reinforcing agent such as carbon black is added, swelling is further suppressed.

On the other hand, as for the affinity between the rubber and the solvent, the closer the polarities of the two are, the more easily the rubber swells. When a solubility parameter is used as an index indicating the polarity, the larger the difference between the solubility parameters, the more difficult it is to swell. That is, a highly polar rubber (having a large solubility parameter) such as a chlorinated rubber or a butadiene / acrylonitrile rubber may be used for an aliphatic oil having a low polarity. Butadiene / 2-
A product obtained by crosslinking a copolymer of methyl-5-vinylpyridine with an organic halide also has high polarity and is excellent in oil resistance. However, all of these rubbers are resistant to aliphatic oils, and no consideration was given to swelling on aromatic oils, especially coal tar and its distillates. The solubility parameters of coal tar and its fractions were also unknown.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cover rubber which is resistant to aromatic oils, in particular, suppresses swelling of coal tar and its distillate.

[0007]

Means for Solving the Problems In order to solve the above problems, the present inventors have estimated the solubility parameter of coal tar and found a solvent having a swelling property close to that of coal tar. By immersing the rubber in the solvent, it is possible to easily determine whether or not the rubber swells with the coal tar and to what extent the rubber swells.

Coal tar is a very complex mixture of polycyclic aromatic hydrocarbons. As a result of composition analysis, naphthalene is the largest at about 10%, and 1- and 2-methylnaphthalene, dimethylnaphthalene, diphenyl , Acenaphthene, fluorene, dibenzofuran, phenanthrene, anthracene, fluoranthene, pyrene, etc. each in an amount of 1 to 3%
Degree included. According to the solvent extraction, the extraction rate with hexane (solubility parameter δ = 7.33) is about 70%, about 90% with toluene (8.97), and about 95% with chloroform (9.30).
%, 2-butanone (9.56), about 94%, acetone (9.7%)
It was about 85% for 4) and about 75% for methanol (14.52). Since the closer the solubility parameter, the better the solubility, the solubility parameter of chloroform and 2-butanone with the highest extraction rate should be close to the solubility parameter of coal tar, and the value was estimated to be 9.30 to 9.56.

[0009] Naphthalene, which is the most common component in coal tar, is a solid at ordinary temperature and hardly swells the rubber in the solid. Thus, a compound contained in coal tar, which has a molecular weight and structure similar to that of naphthalene and is liquid at ordinary temperature, was examined. As a result, Indan and 1,2,3,4-
It has been found that tetrahydronaphthalene (tetralin) exhibits a good swelling effect of coal tar. The tendency of swelling of indane and tetralin to various rubbers is in good agreement with that of coal tar, and the volume increase rate when swollen is slightly higher than that of coal tar. That is, the cover rubber which does not swell with indane and tetralin has no fear of swelling even when used for transferring solids including coal tar, and there is no problem in use. Indane and tetralin have low viscosities, are easy to handle, and can be evaluated quickly and easily.

On the other hand, the solubility parameters of general rubbers are the lowest for silicone (polydimethylsiloxane) rubber at 7.3, and the following are butyl rubber (7.84), ethylene / propylene copolymer (7.95), natural rubber (8.10), and polybutadiene. (8.44), neoprene (8.85), chlorinated rubber (9.4
), Butadiene / styrene (8.1 to 8.67), butadiene / acrylonitrile (8.7 to 10.30), butadiene /
Vinyl pyridine (9.35) and the like. Fluorine rubber is expected to have a smaller value than silicon rubber.
In order to prevent swelling of the rubber belt due to coal tar, a material having a solubility parameter having a large difference from the solubility parameter (9.30 to 9.56) of coal tar may be selected.
In other words, silicone rubber or fluorine rubber with a small solubility parameter, or a large percentage of acrylonitrile (30%
Above) Materials with high solubility parameters, such as butadiene / acrylonitrile copolymers, are advantageous. But,
Although the solubility parameter of coal tar is estimated to be 9.30 to 9.56, the extraction rate with hexane (δ = 7.33) (70
%), The solubility parameter of methanol (1
The extraction rate (75%) according to 4.52) is higher, and the complex coal tar components include polar compounds with large solubility parameters. Therefore, as a material of the coal tar resistant swelling belt, a material having a large difference from the solubility parameter of coal tar and a small solubility parameter is suitable.

Based on the above findings, a material for the cover rubber that hardly swells in an aromatic oil such as coal tar was examined. That is, when immersed in indane or tetralin for 2 hours or more, {(weight after immersion) − (weight before immersion)} /
A rubber having {(density of indane or tetralin) × (volume before immersion)} is 1 or less is used as a cover rubber.
It has been found that it is a cover rubber that hardly swells in aromatic oils. In addition, the constituent unit structure of the cover rubber should include a dimethylsiloxane portion of 10 mol% or more, the cover rubber should contain fluorine in an amount of 30 wt% to 76 wt%, and the surface of the cover rubber should be in indane or tetralin. When immersed for 2 hours or more, ｛(weight after immersion)-
Applying, impregnating or affixing a rubber or synthetic polymer having a (weight before immersion)｝ / {(density of indane or tetralin) × (volume before immersion)} of 1 or less to a thickness of 0.1 mm or more; The constituent unit structure of the rubber or synthetic polymer to be applied, impregnated or affixed should contain at least 50 mol% of a dimethylsiloxane moiety, and 30% by weight or more of fluorine as a constituent element of the rubber or synthetic polymer to be applied, impregnated or affixed.
Weight percent or less of coal tar or fractions of coal tar whose melting point or softening point is 100 ° C or less
It has been found that it is suitable for a cloth conveyor rubber belt for transferring coal containing 0.1% by weight or more.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The swellability is usually evaluated at the rate of volume increase, but there is no simple method for simply measuring the change in volume of a deformed rubber or synthetic polymer material.
On the other hand, weight measurement can be performed relatively easily. However, when trying to substitute the volume increase rate with the weight increase rate, the influence of the specific gravity of the solvent is large. Therefore, swelling property = {(weight after immersion)-(weight before immersion)} / ((density of indane or tetralin) × (volume before immersion)} of rubber or synthetic polymer material The weight of the permeated solvent can be found from (weight after)-(weight before immersion), and the weight is divided by (density of indane or tetralin) x (volume before immersion). Rate. If the rubber or synthetic polymer material before immersion is 0.1 cm ³ or more, it can be measured with sufficient accuracy. Swellability = 0 indicates no swelling, and swellability = 1 indicates that the volume is almost doubled. If the volume is doubled, the strength and hardness decrease, and meandering and loosening become remarkable, making it difficult to use. Therefore, the swelling property must be 1 or less.

The swelling of rubber or a synthetic polymer material is a phenomenon that occurs when a component having a low molecular weight such as a solvent penetrates, and as shown in FIG. 1, the swelling is saturated in about 2 hours. Therefore, it is necessary to measure the swellability after 2 hours or more after immersion.

As a material of the coal tar swelling resistant belt, when immersed in indane or tetralin for 2 hours or more, {(weight after immersion) − (weight before immersion)} /
A material having {(density of indane or tetralin) × (volume before immersion)} is 1 or less, that is, silicon rubber containing 10 mol% or more of dimethylsiloxane part as a constitutional unit structure, or 30 wt% or more of fluorine as a constitutional element Fluorine rubber containing up to 76% by weight is suitable. Silicon rubber has a small solubility parameter, which is due to the effect of the dimethylsiloxane moiety. Others include methylphenyl siloxane, diphenyl siloxane, methyl vinyl siloxane, and cyanopropyl siloxane, all of which have large solubility parameters. Therefore, it is desirable that dimethylsiloxane be a polydimethylsiloxane silicone rubber as a constituent basic structure in an amount of 10 mol% or more, preferably 50 mol% or more, more preferably. Vinylidene fluoride / propylene hexafluoride (20-80 mol% / 80-20 mol%) is a fluorine-containing rubber having a smaller solubility parameter than silicon rubber.
Copolymer, vinylidene fluoride / propylene hexafluoride / ethylene tetrafluoride copolymer (20-60 mol% / 20-60 mol%
/ 20-40 mol%), vinylidene fluoride / ethylene trifluoride chloride (50-90 mol% / 50-10 mol%) copolymer is effective as a cover rubber for a coal tar resistant swelling belt,
More than 30% by weight of fluorine, preferably 40% by weight
Not less than 76% by weight. If it is less than 30% by weight, the effect of the fluoro rubber is small, and if it exceeds 76% by weight, it does not function as an organic polymer material.

Alternatively, a rubber or synthetic polymer further containing 50 mol% or more of dimethylsiloxane in a normal cover rubber, or a rubber or synthetic polymer containing 30% by weight or more of fluorine as a constituent element is 0.1 mm or more, preferably 1 mm or more. It may be applied, impregnated or pasted to a thickness. In practice, it is effective if it can cover the surface of a normal cover rubber, but if it is 0.1 mm or less, it is difficult to apply, impregnate or stick it uniformly, and its mechanical strength is low. When applied, impregnated or affixed, it is not necessarily required to be crosslinked like rubber, and when applied or impregnated, it may be liquid or liquid. When affixing, a synthetic polymer sheet or film may be used. Examples of the fluorine-containing rubber include vinylidene fluoride / propylene hexafluoride (20 to 80 mol% / 80 to 20 mol%) copolymer and vinylidene fluoride / propylene hexafluoride / ethylene tetrafluoride copolymer (20 to 80 mol%). 60 mol% / 20-60
Mol% / 20 to 40 mol%), vinylidene fluoride / ethylene trifluoride chloride (50 to 90 mol% / 50 to 10 mol%) copolymer, as a fluorine-containing synthetic polymer, polytetrafluoroethylene, Ethylene tetrafluoride / alkyl perfluoroalkyl vinyl ether (20-80 mol% / 80-20 mol%) copolymer, ethylene tetrafluoride / propylene hexafluoride (20-80 mol% / 80-20
Mol%) copolymer, ethylene tetrafluoride / ethylene (50 ~
(90 mol% / 50 to 10 mol%) Copolymer, polyvinylidene fluoride and polyvinyl fluoride are effective.

In addition to coal tar, tar distillate, coal carbonate, naphthalene oil,
When transferring solid matter containing 0.1% by weight or more of absorbent oil, tar heavy oil, creosote oil, anthracene oil, coal tar pitch or the like having a melting point or softening point of 100 ° C or less, the above-mentioned ｛(immersion) Weight after)-(weight before immersion) 浸漬 / ｛(density of indane or tetralin)
× (volume before immersion) １ is 1 or less, or swelling can be prevented by using a rubber or a synthetic polymer for the cover rubber, or by applying, impregnating or affixing to the surface of the cover rubber. Coal tar fractions are rich in aromatic hydrocarbons,
If liquid or liquid, it swells the rubber in the same way as coal tar. However, if the melting point or softening point exceeds 100 ° C., there is no swelling effect as in the case of solids. Also, coal tar having a melting point or softening point of 100 ° C. or lower and solids containing less than 0.1% by weight of a fraction of coal tar have no swelling effect like solids.

[0017]

EXAMPLES [Example 1] Butadiene / acrylonitrile (80/20) rubber, ethylene / propylene (60/40) rubber, butyl rubber, chloroprene rubber, silicon rubber (polydimethylsiloxane), fluorine rubber (vinylidene fluoride / 6 After measuring the tensile strength, hardness and weight of the propylene fluoride (40/60) copolymer, immerse it in coal tar and indane, and after 3 hours take out the swollen rubber and remove the adhering coal tar and indane. Wipe,
The tensile strength, hardness and weight after swelling were measured. The swelling evaluation (swellability) was performed by {(weight after immersion)-(weight before immersion)} / {(density of immersed coal tar or indane) × (volume before immersion)}. Table 1 shows the results. Rubber having a high swelling property has a remarkable decrease in both tensile strength and hardness, causing problems in deformation and abrasion resistance. When the butadiene / acrylonitrile rubber was swollen after indane immersion and dried, the elasticity was reduced and the rubber became very brittle. This is presumably because additives (such as plasticizers) in the butadiene / acrylonitrile rubber eluted into the indane. A similar phenomenon is expected to occur when coal tar is used for a long time. Rubber having a swelling property of 1 or less has a reduction in tensile strength and hardness of 10% or less, and does not cause any practical problem. In addition, the tendency of swelling by coal tar and indane is consistent, and those that easily swell with coal tar swell to the same extent with indane.

[0018]

[Table 1]

Example 2 Butadiene / acrylonitrile (80/20) rubber, ethylene / propylene (60/40) rubber, butyl rubber, chloroprene rubber, butadiene / 2-
Methyl-5-vinylpyridine (80/20) rubber, silicon rubber (polydimethylsiloxane), fluorine rubber (vinylidene fluoride / propylene hexafluoride (40/60) copolymer)
Were cut into 5 mm square cubes, immersed in coal tar, tar gas oil, naphthalene oil, absorbent oil, creosote oil, anthracene oil, indane and tetralin for 3 hours to evaluate swellability. Table 2 shows the results. In any case, the swellability is 1 or less only for the two types of fluorine rubber and silicon rubber.

[0020]

[Table 2]

Example 3 Silicon rubber (polydimethylsiloxane), ethylene / propylene (60/40) copolymer, and butadiene / acrylonitrile (80/20) copolymer were each cut into a 5 mm square cube. It was immersed in indane to evaluate the swellability with time. The result is shown in FIG. The swelling of each material reaches saturation in about 2 hours.

[0022] Example 4 60 mesh or less called coal pulverized to a tar, tar light oil, naphthalene oil, absorption oil, creosote oil, about 20 cm ³ obtained by addition of anthracene oil each 3 percent by weight and silicon rubber (poly Dimethylsiloxane), fluorine rubber (vinylidene fluoride / propylene hexafluoride (40/60) copolymer), ethylene tetrafluoride resin (sheet), ethylene / propylene (60/40) copolymer, butadiene / acrylonitrile ( 80/20) Each of the copolymers cut into cubes of 5 mm square was mixed, placed in a glass container, sealed, and evaluated for swellability after 3 hours. Table 3 shows the results. Although the swellability was lower than that of coal tar and the fractionated product alone, the swellability was 1 or more and the hardness was low except for silicone rubber, fluororubber and polytetraethylene sheet.

[0023]

[Table 3]

Example 5 A butadiene / acrylonitrile (80/20) copolymer was cut into 5 mm squares, and the surface thereof was coated with polytetrafluoroethylene (PTFE), mainly containing polydimethylsiloxane. The swellability of those coated with a silicone filler (putty) was compared. Table 4 shows the results. PTFE is effective only by covering the surface thinly. Silicon putty could not be applied thinly due to its high viscosity, but was less effective than PTFE, but was swellable enough to be used practically as a conveyor belt.

[0025]

[Table 4]

[0026]

By immersing the rubber in indane or tetralin and evaluating it, it is possible to easily determine whether or not the rubber material swells due to coal tar and its distillate, and to obtain the resulting swelling. If the property = {(weight after immersion) − (weight before immersion)} / {(density of indane or tetralin) × (volume before immersion)} is less than 1, coal tar and its fractionated product It can be suitably used as a cover rubber of a conveyor belt for transferring solid matter containing.

[Brief description of the drawings]

FIG. 1 is the immersion time (hour) on the horizontal axis and the swelling property on the vertical axis =
A graph showing {(weight after immersion)-(weight before immersion)} / {(density of indane or tetralin) × (volume before immersion)}, the time of the amount of the component permeating into the rubber material after immersion. It shows the time required from each change to saturation.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenji Kato 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Masahiko Yokomizo 20-1 Shintomi, Futtsu-shi, Chiba New Japan (72) Inventor Yasutaka Murasaki, 20-1 Shintomi, Futtsu-shi, Chiba Prefecture

Claims (12)

[Claims] 1. When immersed in indane or 1,2,3,4-tetrahydronaphthalene for 2 hours or more, {(weight after immersion) − (weight before immersion)} / {(indan or 1,2,2, Density of 3,4-tetrahydronaphthalene) ×
A cloth-layer conveyor rubber belt, wherein a rubber having (volume before immersion)｝ is 1 or less is used as a cover rubber. 2. The cloth conveyor rubber belt according to claim 1, wherein the cover rubber contains a dimethylsiloxane portion as a constituent unit structure in an amount of 10 mol% or more. 3. As a constituent element of the cover rubber, fluorine is used.
2. The composition according to claim 1, wherein the content is not less than 76% by weight.
The cloth layer conveyor rubber belt as described in the above. 4. A cover rubber comprising vinylidene fluoride / propylene hexafluoride copolymer, vinylidene fluoride / propylene hexafluoride / ethylene tetrafluoride copolymer, vinylidene fluoride / ethylene trifluoride chloride copolymer 4. The cloth layer conveyor rubber belt according to claim 1, wherein the belt is any one of fluororubbers. 5. Coal tar or a fraction of coal tar having a melting point or softening point of 100 ° C. or less is 0.1%.
The cloth-layer conveyor rubber belt according to any one of claims 1, 2, 3, and 4, wherein a solid material containing at least weight% is transferred. 6. The fabric according to claim 5, wherein the coal tar fraction is tar light oil, calcified oil, naphthalene oil, absorption oil, tar heavy oil, creosote oil, anthracene oil, or coal tar pitch. Layer conveyor rubber belt. 7. The cloth layer conveyor rubber belt according to claim 5, wherein the solid material is coal. 8. When immersed in indan or 1,2,3,4-tetrahydronaphthalene for 2 hours or more on the surface of the cover rubber, {(weight after immersion) − (weight before immersion)} /｝ ( A rubber or synthetic polymer having a density of indane or 1,2,3,4-tetrahydronaphthalene x (volume before immersion) x 1 or less is applied, impregnated or affixed to a thickness of 0.1 mm or more. And cloth layer conveyor rubber belt. 9. The cloth conveyor rubber belt according to claim 8, wherein a dimethylsiloxane part is contained in an amount of 50 mol% or more as a structural unit structure of rubber or a synthetic polymer. 10. The cloth layer conveyor rubber belt according to claim 8, wherein fluorine is contained as a constituent element of rubber or synthetic polymer in an amount of 30% by weight or more and 76% by weight or less. 11. A rubber comprising vinylidene fluoride / propylene hexafluoride copolymer, vinylidene fluoride / propylene hexafluoride / ethylene tetrafluoride copolymer, vinylidene fluoride / vinylidene fluoride
11. The cloth conveyor rubber belt according to claim 8, wherein the rubber belt is any one of a fluororubber of ethylene trifluoride chloride copolymer. 12. The synthetic polymer is polytetrafluoroethylene,
It should be ethylene tetrafluoride / alkyl perfluoroalkyl ether copolymer, ethylene tetrafluoride / propylene hexafluoride copolymer, ethylene tetrafluoride / ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride The cloth-layer conveyor rubber belt according to claim 8 or 10, wherein: