JPH10140039A - Carbon black molded form for rubber compounding and carbon black-containing rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject molded form capable of giving rubbers low in dissipation factor and heat generation, by compounding rubber ingredients with carbon black pressure-molded under a specified pressure. SOLUTION: This molded form is a carbon black pressure-molded form coated with pref. a heat-shrinkable material or a material soluble to or miscible with rubber. The other objective rubber composition is obtained by compounding homogeneously dispersing 100 pts.wt. of at least one kind of rubber selected from the group consisting of natural rubber and diene-based synthetic rubber with 30-150 pts.wt. of carbon black molded under a pressure of 2-1,000kgf/cm<2> and coated, exhibiting high dispersibility, low dissipation factor and low heat generation; thereby resolving such problems as environmental pollution due to dusting during rubber kneading operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition comprising natural rubber or synthetic rubber and carbon black. In particular, the present invention relates to a technique capable of producing a rubber having high dispersibility of carbon black in rubber, low heat generation, and low loss coefficient (low tan δ) by using carbon black of a specific form. In addition, the form of the carbon black to be blended is one in which the density is greatly improved, and the transportation and storage costs of the carbon black itself can be greatly reduced. Further, by forming carbon black under pressure and coating it with a soluble material, it is possible to prevent environmental pollution due to dust generation, which is a major problem when using carbon black.

[0002]

BACKGROUND OF THE INVENTION Rubber compositions for tires include natural rubber (NR) and styrene-butadiene copolymer rubber (SB).
R) and a blend of rubber such as polybutadiene rubber (BR) and carbon black as a reinforcing filler for these rubbers have been used in the past.

[0003] In 1915, a British tire manufacturer considered adding a color to distinguish it from other brands. By coincidence, they found that the wear resistance of a tire to which carbon black was added was dramatically improved. Since then, the mixing processability of rubber for tires, rubber elasticity, and heat build-up have been improved by appropriately setting the type and amount of rubber, the type, characteristics and amount of carbon black, and the type and amount of oil to be compounded. Various characteristics such as wear resistance and other mechanical properties have been improved. Particularly in recent years, from the viewpoint of energy saving, improvement of rolling resistance has been highlighted and various improvements have been proposed.

The following commentary is given in the section on rolling resistance (P.67) by Rokuro Hattori, "Tale of Tires" (Taiseisha). "General flat roads with ordinary cars
When running at Km, the rolling resistance of the tires accounts for almost 50% of the total resistance of the vehicle.
You can see how the rolling resistance of the tires has a significant effect on the driving performance and fuel efficiency of a car. The rolling resistance of the tire is considered to be composed of the following three factors. In other words, (1) Loss due to repeated deformation of each part that occurs when the tire rolls (2) Friction between the road surface and the tire on the ground contact surface of the tire (3) Rotation of the tire This is due to air resistance when moving forward. Although the ratio of these three components depends on the running speed, the friction component of (2) is approximately 5 to 10% and the air resistance component of (3) is approximately 1%.
It is said to be ３3%, and the rest is occupied by loss due to repeated deformation. That is, most of the rolling resistance is due to the hysteresis loss generated in the tire structure, and eventually raises the temperature of the tire as heat, which is eventually dissipated to the outside world. 』

As is apparent from the above description, various attempts have been made for a long time to reduce the rolling resistance and, consequently, the hysteresis loss, which are extremely important factors in rubber products, particularly in tire applications. For example, there is an attempt to improve the basic skeleton of carbon black blended in rubber. In Japanese Patent Publication No. 59-89339, carbon black having a specific coloring power is used. JP-A-54-13459 and JP-B-58-46259 use carbon black having a specific compression DBP.

[0006] There has been an attempt to focus on carbon black aggregates. For example, JP-A-6-136288 and JP-B-6-37581 use carbon black in which the most frequent value of the diameter of the aggregate is specified. In JP-A-6-207052 and JP-B-6-37594, carbon black having a specified aggregate distribution is used. JP-B-6-37582 and JP-B-6-41540 use carbon black in which aggregate pores are specified. JP-A-5-179065
In Japanese Unexamined Patent Publication No. Hei 5-18339, it is disclosed in Japanese Patent Publication No. 18339/1993 that low-temperature plasma treatment increases phenolic hydroxyl groups on the surface of carbon black to reduce carboxyl groups. Japanese Patent Application No. 98074 describes that an exothermic improving agent is added.

[0007] There is also an attempt on a method of granulating carbon black for rubber. For example, Japanese Patent Publication No. 6-89269 discloses that a water-soluble nonionic surfactant is added during wet granulation of carbon black.
No. 664 describes that granulation is performed by adding a polyoxyethylene type nonionic surfactant. Also,
JP-A-7-3079 describes that carbon black is kneaded with an additive oil in advance and then mixed with rubber.

In Japanese Patent Application Laid-Open No. 3-259962, a water slurry of carbon black is suction-filtered, dried as a block, and casein / starch powder is applied to the surface of the block.
Attempts have been made to improve the handleability by applying a polyvinyl alcohol aqueous solution and a styrene-butadiene latex or an acrylic latex. However, in this method, it is necessary to prepare a slurry of ultrafine carbon black, and then filter and dry the slurry, which requires a great deal of labor and cost. In addition, the obtained block is considered to have greatly reduced dispersibility.

[0009] Even with the prior art described above, the demand for fuel-efficient tires has not yet reached a sufficient level. In addition, some of these technologies are questionable in terms of cost for industrial adoption. on the other hand,
Quality requirements for fuel-efficient tires are becoming increasingly sophisticated, and some kind of response is required.

[0010]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and found that carbon black molded under pressure at a specific pressure is blended with a rubber component to obtain a loss factor and heat generation. It has been found that a small amount of rubber can be produced. Further, the molded article was easily coated, and the carbon black molded article having the obtained coating was found to be particularly excellent in the effect of preventing environmental pollution.
That is, the present invention relates to a method of coating and coating 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and diene-based synthetic rubber at a pressure of ² to 1000 ° F / cm ² to form a coated carbon. It is present in a carbon black-containing rubber composition or the like obtained by blending, mixing and dispersing 30 to 150 parts by weight of black. According to the present invention, there is no density unevenness in the particles that is difficult to avoid by performing wet granulation of carbon black, and it is possible to arbitrarily change the powder having the required hardness only by appropriately setting the molding pressure. it can. Since the dispersion of carbon black in the rubber is improved, a rubber having low heat build-up and low loss can be produced. The present invention is basically not affected by the basic structure or the aggregation state of carbon black. Also, no enormous energy or huge equipment is required for wet granulation of carbon black, and no special or expensive processing or machine is required. According to the present invention, a rubber composition having high characteristics can be obtained extremely inexpensively and effectively.

Furthermore, since the density of the carbon black used has been greatly improved, the cost required for transportation and storage can be greatly reduced. In addition, by forming carbon black under pressure and coating it with a soluble material, environmental pollution due to dust generation, which was a major problem when using carbon black, has been solved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, in the present invention, carbon black is subjected to pressure molding to form a pressure molded body. As the carbon black to be subjected to pressure molding, those conventionally used for compounding with rubber can be used without limitation. For example, carbon black, acetylene black, lamp black, channel black, Ketjen black manufactured by the furnace method And the like. These various carbon blacks may be appropriately selected according to the characteristics of the rubber composition intended.

When furnace black produced by the furnace method is used among the above-mentioned carbon blacks, a very remarkable effect is exhibited in maintaining the dispersibility. Furthermore, the effect of low hysteresis loss of the obtained rubber composition also becomes large. Further, those obtained by post-treating these various carbon blacks with various oxidizing agents and the like can also be used. These various carbon black powders,
Granules can be used without any particular limitation. Examples of the granules in this case include granules obtained by ordinary wet granulation and dry granulation and, for example, JP-A-2-1428.
As described in JP-A-58-158 and JP-A-3-193129, flake-like carbon black obtained by using a roller compactor or the like may be used.

The particle size of the carbon black is not particularly limited, but the effect of improving dispersibility and handleability is particularly high in the range of a small particle size of 1 to 60 nm, especially 1 to 50 nm. Carbon black having a fine particle diameter in this range has strong cohesiveness between carbon blacks,
Dispersion was particularly difficult when producing paints. Another advantage is that the more difficult these carbon blacks are to disperse, the more the advantages of the present technology can be exhibited.

In the present invention, these carbon blacks are molded under pressure. At this time, a mold of any material may be used as long as it has a strength capable of withstanding an applied pressure during molding. For example, as a metal mold, SUS3
For example, a stainless steel mold such as SUS316 and SUS316, a carbon steel mold, and a super steel such as tungsten carbide can be used.
As the resin mold, polytetrafluoroethylene (PTF)
E) (trademark: “Teflon”), a mold made of a fluororesin such as poly (ethylene trifluoride chloride) (PCTFE), polytetrafluoroethylene / propylene hexafluoride (FEP), nylon,
Plastics such as polyethylene, polycarbonate and phenolic resin, and CFRP and GFR as composite materials
FRP such as P, ceramic molds include alumina,
Zirconia, mullite and the like can be used. By making the mold used for molding slidable, pressure molding can be easily performed.

The size of the mold is not limited, but practically, it is 1 cc or more, preferably 100 cc or more. If it is less than 1 cc, transportation becomes complicated. If necessary, a large molded body may be produced, cut into a suitable size, and transported and used as an aggregate. It is preferable to mold the obtained molded body to have a size of 1 cc or more. In addition, molds of various shapes can be used in order to obtain a shape of a molded body according to the purpose and use situation.
For example, in addition to the prismatic shape suitable for loading a large amount, rollability, cylindrical shape in consideration of easy loading into the kettle at the time of use, holes, cuts etc. in consideration of dispersibility in the vehicle There may be.

If the shape of the carbon black molded body is a columnar body having a polygonal cross section, in particular, a rectangular parallelepiped or a cube, a truck, a wagon or a warehouse for transporting carbon black is generally a rectangular parallelepiped. Can be filled with a carbon black molded body without gaps, which is particularly preferable for reducing transportation costs and warehouse storage costs. As presses used for pressurization, mechanical presses such as hydraulic mechanical presses, hydraulic hand presses, mechanical presses,
There is no particular limitation as long as it can pressurize the powder, such as an air cylinder press, a dry rubber press, a wet rubber press, a frame rubber press, a bleach rubber press, and a rubber pad powder molding press.

The carbon black is placed in the above-mentioned mold and molded by pressing. The pressure during molding under pressure (molding pressure) is ^{2 to} 1000 kgf / cm ² , preferably ^{2 to} 500 kgf / cm ² .
cm ² , particularly preferably 5 to 400 kgf / cm ² . If the molding pressure is lower than ² kgf / cm ² , the compactness tends to decrease and the powdering rate tends to increase. On the other hand, when the molding pressure is higher than 1000 kgf / cm ² , the dispersibility may not be sufficient with a dispersing machine used during the production of a normal rubber composition. Further, even if the pressure is further increased, the effect of improving compactness can hardly be obtained. For this reason, as a carbon black molded body used as a pigment when industrially producing a paint, it is appropriate to perform pressure molding at 1 to 1000 kgf / cm ² .

It is desirable that the density of the obtained molded product is in a range having the following relationship with the DBP oil absorption and the particle size of the carbon black used. That is, the density ρ (g
/ Cc), ρ = 8.190 × 10 ⁻³ D−3.824 × 10 ⁻³ L +
0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 It is preferable to set the following.

More preferably, ρ = 8.686 × 10 ⁻³ D−4.031 × 10 ⁻³ L +
0.543 or more, ρ = 3.123 × 10 ^-3 D-3.189 × 10 ^-3 L +
1.072 or less is particularly preferable.

In each of the above formulas, D (nm) is the arithmetic average particle diameter of carbon black by an electron microscope, L (m
1/100 g) is the DBP oil absorption. Here, the DBP oil absorption is a value measured by a method based on JIS K6221-1982. The particle size of the carbon black is a value measured by the method described below.
Put carbon black into chloroform and add 200KHz
Is dispersed for 20 minutes, and the dispersion sample is fixed to a support film. This is photographed with a transmission electron microscope, and the particle diameter is calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and the values are obtained by arithmetic averaging.

When the density is in the above range, a molded article excellent in handleability can be obtained without impairing the basic properties of carbon black such as dispersibility in a rubber component. Such effects are particularly remarkably exhibited in the range described above as the more preferable range. That is, when the density is smaller than the above range, the handleability and the dust prevention effect may be poor. On the other hand, if the density is higher than the above range, the handling efficiency and the effect of preventing dusting are further reduced, and the dispersibility in the rubber component tends to decrease.

The pressure-molded carbon black used in the present invention preferably has a powdering ratio of 40% or less, more preferably 20% or less. The powdering rate is determined by a measuring method described below. That is, a carbon black pressure molded body is precisely weighed to 25 ± 1 g (W) and put into a sieve having a diameter of 200 mm and a mesh size of 1 mm in accordance with JIS K-6221. A tray and a lid are attached to the sieve, and the plate is shaken with a shaker according to JIS K-6221 for 20 seconds. Remove the pan from the shaker and reduce the weight of carbon black in the pan to 0.0
And 1g Madeseihakari, and the weight (W _R) after shaking it, is a value obtained by the following equation. Powdering rate _{(%) = (W R /} W) × 100 powdering rate by 40% or less, it is possible to prevent powdering due to an external force of vibration or friction applied to the molded body during transportation, handling property Especially excellent.

The ratio between the bulk density of the powdery or granular carbon black subjected to the pressure molding and the density of the carbon black molded body (hereinafter, also referred to as "bulk density ratio") is 2.5.
It is good to make it 8 times, more preferably 3 to 7 times. If the bulk density ratio is lower than 2.5, the compactness of the molded body tends to decrease. Further, the strength of the molded body may be inferior. On the other hand, when the bulk density ratio exceeds 8, the dispersibility tends to decrease. When the bulk density ratio is 2.5 or more and 8 or less, compactness and dispersibility in varnish are simultaneously satisfied in an extremely preferable range. At the time of pressure molding, a mode in which the gas between the carbon black particles is degassed in advance by using a decompression chamber and then pressure molding is performed may be adopted. For example, using the apparatus shown in FIG. 1, the following method can be adopted.

First, FIG. 1 shows a molding machine that can be used in the present invention and a series of molding operations (filling, vacuum degassing, pressurization, and termination). Here, in FIG. 1, 1 is a hydraulic cylinder (upper),
2 is a cylinder, 3 is a vacuum chamber, 4 is an upper punch,
5 is a lower punch, 6 is a die, and 7 is a hydraulic cylinder (lower). As shown in FIG. 1, a mold having a slidable cylinder and a piston is filled with carbon black powder as a raw material to be molded. The inside of the vacuum chamber and the inside of the cylinder set at the top of the cylinder are substantially isolated from the outside by the gasket material. Next, the vacuum pump connected to the vacuum chamber is operated to keep the vacuum state, and the piston is lowered to press-mold the carbon black in the cylinder. Thereafter, the operation of the vacuum pump is stopped, and the atmospheric pressure in the chamber and the cylinder is returned to the atmospheric pressure. After that, by raising the vacuum chamber and piston and taking out the carbon black molded body,
The degassing of the gas between the carbon black particles by the decompression chamber and the subsequent pressure molding of the carbon black can be performed.

At this time, the pressure at the time of pressure reduction is 0.01 to 50.
It is preferably performed at 0 Torr. At 500 Torr or less, degassing between particles is very easy, while 0.0
Even if it is less than 1 Torr, it does not show exceptional advantage,
This is because the complexity of high vacuum is only increased. The carbon black molded article obtained in this way is further coated to obtain a carbon black molded article for rubber compounding of the present invention. The carbon black pressure molded body described above is
Maintains the basic characteristics of carbon black such as dispersibility in vehicle and can further improve the effect of reducing hysteresis loss when made into a rubber composition, and at the same time, has extremely excellent handling properties and is substantially handled. It has no problem of dusting, and has sufficient strength to maintain its shape without collapse even when it is loaded into a container or the like and loaded. For this reason, it is easy to provide a coating described below on such a carbon black pressure molded article, and the carbon black molded article for rubber compounding having the obtained coating is particularly excellent in handleability.

Here, the coating is not particularly limited, as long as there is some cover on the surface of the carbon black molded body and the molded body is shielded from the outside. Specifically, the degree of coating is not limited, and can be appropriately selected depending on the use, transportation, and storage environment. For example, coatings using various film-forming resins and papers are typical, but not limited thereto. Various materials, for example, a porous body may be used, and it is not necessary to cover the entire surface of the molded body. There is no need to be in close contact with the body. The thickness of the coating is not particularly limited, and usually about 5 to 500 μm is appropriate. 10 to 5 when packing with sheet-like material
About 0 μm, when coating with a curable material, about 50 to 100 μm is appropriate, but is not limited to these ranges, as long as it has a coating that can achieve the desired purpose. .

The means for forming the coating is not particularly limited.
Typical examples include sheet-like packaging and coating with a curable liquid material such as a resin composition, but are not limited thereto. The form of the packaging is not particularly limited. For example, in addition to shrink packaging in which a package is formed by coating with a heat shrinkable material and heating, or vacuum packaging, a molded body is coated with a curable liquid material and cured. Then, a film can be formed on the surface of the molded body, and this can be used as a package.
In the case of coating, it is also possible to coat the molded body using a material which is liquefied by dissolving the coating material with a solvent or heat-melting.

The package does not necessarily have to be sealed. What is necessary is just to select suitably according to a use purpose, work environment, etc. The packaging method is not particularly limited. For example, film packaging such as shrink packaging, vacuum packaging, vertical pillow packaging, horizontal pillow packaging, stretch packaging, skin packaging, and folding packaging.
Boxed packaging such as carton packaging, overwrap packaging, and potion packs. Blister packaging, skin packer and the like. Of these, in particular, by vacuum packaging, shrink packaging, or coating with a curable liquid material having film forming properties, a coating substantially adhered to the carbon black molded body is formed by oxidation from the surface of the molded body. The effects of preventing quality deterioration, improving strength, handling properties, and reducing transportation and storage costs are great, and the coating can be easily formed. The method of forming the coating is not limited, but examples include coating, such as spraying, air doctor coating, blade coating, rod coating, knife coating, and impregnating coating.

By providing a coating on the carbon black molded body in this way, an effect of preventing environmental pollution due to dust generated when using carbon black can be obtained.
In the present invention, since the carbon black molded body has a sufficient strength, various means can be adopted for coating the carbon black molded body. In addition, the obtained coated carbon black molded body has more sufficient strength and does not lose its shape. It is easy to form the coating in close contact with the carbon black molded body, and the thickness of the coating can also be arbitrarily adjusted. Therefore, by appropriately selecting the coating material, the strength can be improved, the impact can be easily absorbed, and the effect of preventing the carbon black molded article from being damaged during transportation is great.

In particular, by selecting and coating an appropriate material as a coating material, carbon black can be used without removing the coating when used, which is a very effective prevention measure against environmental pollution. For example, if the rubber composition is coated with a soluble material that is soluble or miscible in the vehicle, it can be put into the vehicle without unpacking, which is very preferable in terms of work efficiency. Here, the term “dissolved” refers to a state in which the rubber composition is substantially dissolved. There is no problem unless it adversely affects the characteristics of the above. In addition, the term “mixing” refers to mixing in a uniform appearance.

Specific examples of the soluble material include the following. ABS resin, polyacrylamide, polyacrylic acid, polyacrylic acid ester, polyacrylonitrile, polyacrylonitrile ester, styrene, polymethacrylamide, polymethacrylic acid, polymethacrylic acid ester, acrylic resin such as polymethacrylonitrile, ionomer, Chlorinated polyether,
Coumarone-indene resin, regenerated cellulose, petroleum resin,
Alkaline cellulose, cellulose ester, aerulose acetate, cellulose acetate butyrate, cellulose xanthate, cellulose nitrate, cellulose ether, carboxymethyl cellulose, cellulose ether ester, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose , Cellulose derivatives such as celluloid, FEP, polychlorotrifluoroethylene, polytetrafluoroethylene, polyvinylidene fluoride, fluorine resin such as polyvinyl fluoride,
Nylon 11, Nylon 12, Nylon 6, Nylon 6
10, nylon 612, nylon 66, etc., aliphatic polyamides, polyphenylene terephthalamide, polyphenylene terephthalamide, etc., polyamide imide, polyamide such as polyamic acid, polyarylate, polyethylene terephthalate, polyvinylidene chloride, polyvinyl chloride, chlorinated polyethylene, chloro Sulfonated polyethylene, further high molecular weight polyethylene, low molecular weight polyethylene, high density polyethylene, medium density polyethylene, low density polyethylene, polyethylene such as LLDPE, polybutene such as polyisobutylene, polyolefin such as polypropylene, polycarbonate, polystyrene, polyether sulfone,
Polysulfone such as polysulfonamide, polyvinyl alcohol, polyvinyl cinnamate, polyvinyl acetate, polyvinyl propionate, polyvinyl stearate, polyvinyl butyral, polyvinyl formal, polyvinyl ester such as polyvinyl pyrrolidone, polyvinyl ether such as polyisobutyl vinyl ether and polymethyl vinyl ether , Polyphenylene oxide, polybutylene terephthalate, polypropylene, polymethylstyrene, polymethylene, polyethylene oxide, polyvinyl stearate, hydrochloric acid rubber, cyclized rubber, gum arabic, copearl gum, polyurethane resin, diallyl phthalate resin, urea resin, melanin resin, urethane resin , Butadiene resin, polybutylene terephthalate, rosin resin, petroleum resin, Gilsonite, Rukido resins, modified alkyd resins,
Examples include shellac, dammar, rosin-modified maleic resin, styrene-modified maleic resin, nitrified cotton, casein, starch, saccharides, ABS resin, and liquid crystal polymer.

Others: ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methacrylic acid random polymer, ethylene / acrylic acid copolymer, ethylene / ethylene acrylate copolymer, ethylene / vinyl chloride copolymer Coalesce, ethylene / vinyl acetate / vinyl chloride graft resin, ethylene / vinyl alcohol copolymer, carboxyvinyl copolymer, polyacetal,
There are copolymers such as N-vinylpyrrolidone / vinyl acetate copolymer and methyl vinyl ether / vinyl acetate copolymer.

Amino resins such as aniline resin, urea resin, polysulfonamide and melanin resin, allyl resins such as CR-39 and diallyl phthalate resin, alkyd resins, epoxy resins, silicone resins, vinyl ester resins, novolak resins, resorcinol resins Phenolic resin, etc.
Unsaturated polyester resins, furan resins and the like can also be used.
The carbon black for rubber compounding of the present invention thus obtained is particularly excellent in handling properties and environmental pollution prevention effects. For example, as described above, the dust generation during use can be reduced to almost zero by directly charging the vehicle.

Further, since the density of the carbon black portion is sufficiently high, the effect of reducing the transportation and storage costs is remarkable, and since the deaeration between particles is sufficiently performed, the dispersibility in the vehicle is particularly excellent. ing. For example, it is difficult to sufficiently remove the air between the particles and to bond the carbon black particles to each other so as to form a molded body by a method of filling the bag with powder and degassing. In other words, the decompression system cannot suck the powder into the air sufficiently during the depressurization. Further, in this method, the pressure is about the atmospheric pressure, so that the volume cannot be sufficiently reduced, and it is still insufficient to eliminate the bulky state. Also, even if the entire wrapper is pressurized, sufficient pressure is not applied to the carbon black, and it is not easy to obtain a molded body. Nothing developed its properties. On the other hand, the carbon black for compounding a rubber composition comprising the carbon black molded under pressure of the present invention can be easily produced by the above-mentioned method.

The pressure-molded carbon black described above is mixed with a rubber component, mixed and dispersed to obtain a carbon black-containing rubber composition. The method of mixing and dispersing here is not particularly limited, and a known method can be employed. However, even if the pressure-molded carbon black is used in the size removed from the mold used for molding, the injection port of the kneading machine is used. Crushed to a diameter of about 0.1 mm to 1 cm in order to reduce the size to less than or equal to the size may be introduced into a kneader. Even when crushed one is used, the dispersibility improvement and the low hysteresis loss effect can be exhibited. Here, the crushing method is not particularly limited. For example, if a shearing crusher such as a cutting mill, a rotary crusher, or a shearing roll mill is used, the density of the particles is not condensed at the time of crushing, which is preferable. .

The carbon black for rubber compounding of the present invention can be dispersed in a vehicle without appropriately removing the coating by appropriately selecting the material of the coating, thereby greatly improving the working environment and operating efficiency. Is as described above, but it is of course possible to remove the coating before use. In this case, the number of working steps is increased, but the range of choice of the coating material is widened.

The rubber component used in the present invention is not particularly limited. That is, any one or more of natural rubber and synthetic rubber may be used, and this is blended with the above-mentioned pressure-molded carbon black and mixed and dispersed to obtain a rubber composition. At this time, the compounding amount is 30 to 150 with respect to 100 parts by weight of rubber.
Parts by weight are appropriate. Thereby, it is possible to obtain a rubber having a small loss coefficient and a small calorific value.

The rubber used at this time is not particularly limited.
For example, styrene-butadiene rubber (SB) is used as a synthetic rubber.
R), butadiene rubber (BR), isoprene rubber (I
R), chloroprene rubber (CR), nitrile butadiene rubber (NBR), isobutylene isoprene rubber (II
R), ethylene propylene rubber (EPM), silicone rubber, fluorine rubber, chlorosulfonated polyethylene (C
SM), chlorinated polyethylene (CM), polysulfide rubber, urethane rubber (AU), acrylic rubber (ACM), epichlorohydrin rubber (ECO), propylene oxide rubber (PO), ethylene / vinyl acetate copolymer (EVA),
Liquid rubber, polyalkylene sulfide, nitroso rubber, and the like, natural rubber, and a mixture of the above rubbers are exemplified. Furthermore,
If necessary, vulcanizing agents, crosslinking agents, vulcanization accelerators, vulcanization accelerators, activators, dispersants, vulcanization retardants, antioxidants, reinforcing agents and fillers other than carbon black, softeners , Plasticizer,
Tackifier, colorant, curing agent, foaming agent, lubricant, solvent, surfactant, emulsifier, stabilizer, wetting agent, thickener, coagulant,
Gelling agents, creaming agents, preservatives, defoamers and the like can also be added.

The rubber black component of the present invention is added to the rubber component and kneaded to obtain a rubber composition. The kneader used here may be the one usually used as a rubber kneader, for example, a roll mixer for a batch type open type, a Banbury type mixer for a batch type closed type, and a single screw kneading and extrusion for a continuous screw type. , A twin-screw kneading extruder, a single-screw kneader for a continuous rotor type, and a twin-screw kneader for a continuous rotor type.

Example 1 (1) Production of Carbon Black Molded Body A carbon steel (“SS400”) made by Yuken Co., Ltd. (internal method: 150 mm × 150 mm, height: 360 mm) was mounted on Mitsubishi Chemical Corporation.
500 g of carbon black "DIA-I" (ungranulated product) (particle diameter 24 nm, DBP oil absorption 114 cc / 100 g carbon black, bulk density 0.169 g / cc) is set in a 20-ton hydraulic press manufactured by Yuken Co., Ltd. did. Pressure molding was performed at a molding pressure of 88.9 ° f / cm ² , and the molded density was measured to be 0.522 g / cc.

(2) Packaging A universal sealer manufactured by Kyowa Machine Co., Ltd. (model: "T-6") set with a polyethylene ethylene film having a thickness of 20 μm.
00 ”), the above-described carbon black molded body was set, and hot-sealing sealing was performed at 150 ° C. for 2 seconds to form a bag.
The polyethylene film containing the carbon black molded body was placed in a Kyowa Machine Universal Shrink Tunnel (model: “NS-450”) set at 150 ° C.
Heat shrink for 0 seconds.

(3) Rubber Kneading The wrapped carbon black molded product was mixed with the following composition using a Banbury mixer and an open roll mixer to prepare a rubber composition. Natural rubber (“SMR-L”) 100 parts Wrapped carbon black molded body 50 parts Zinc flower 5 parts Stearic acid 3 parts Antioxidant (Monsanto “Santoflex13”) 1 part Sulfur 2 parts Vulcanization accelerator (Large) (Noxeller CZ manufactured by Uchi Shinkosha) 0.7 parts

(4) Rubber Test These rubber compositions were press-vulcanized at 160 ° C. to prepare vulcanized rubber test pieces. Each test was performed by the following test methods, and the physical properties were measured. Loss Factor The loss factor (tan δ) was measured using “DVE Rheospectral” manufactured by Rheology Co., Ltd. under the following conditions. Static strain 10%, dynamic strain (amplitude) 2%, frequency 10 Hz, measurement temperature 60 ° C. Exothermicity Exothermicity was measured using a Goodrich Flexometer manufactured by Ueshima Seisakusho under the following conditions. Test temperature 35
° C, load 24 pounds, test time 25 minutes

Degree of dispersion of reinforcing particles in rubber (D%): Method for measuring the degree of dispersion of carbon black The method was based on the ASTM D2663-B method (aggregate count method). That is, the vulcanized rubber is sludge-type microtome (L
sliced into thin films by Eitz Co., Ltd., and the total cross-sectional area occupied by agglomerates of reinforcing particles (carbon black) of 5 μm or more in the composition is measured with an optical microscope, and the total cross-sectional area of the reinforcing particles added to the composition (calculated value) The percentage of the reinforcing particles dispersed within 5 μm or less was determined from the above, and was defined as the degree of dispersion (D%). As a result, the loss coefficient at 60 ° C. was 0.139, and the exothermicity was 3
1.0 ° C, D% was 99.2%. Table 3 shows the results.

(Comparative Example 1) The same operation as in Example 1 was carried out except that carbon black was changed to "DIA-I" (wet granulated product) (bulk density: 0.351 g / cc) manufactured by Mitsubishi Chemical Corporation. A rubber test was performed. As a result, the loss coefficient at 60 ° C. was 0.152, the heat build-up was 35.0 ° C., and the D% was 95.4%. Further, the carbon black granulated product scattered fine powder mixed in the granulated product at the time of measurement, and contaminated the surrounding environment.

(Comparative Example 2) The same operation as in Example 3 was performed except that the carbon black molded body was used without packaging. As a result, the loss coefficient at 60 ° C. was 0.140, the heat build-up was 31.4 ° C., and the D% was 99.1%. Further, although the dusting of the carbon black molded article was significantly reduced as compared with the raw material powder, the measures against environmental pollution were not sufficient as compared with the packaged carbon black molded article used in Example 1. Table 3 shows the results.

[0048]

[Table 1] Table 1 Examples and Comparative Examples ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Carbon black Loss factor Exothermicity (℃) ─────────────────────────────────── Example 1 Packaged carbon black molded body 1.39 31.3 Comparative Example 1 Granulated carbon black 1.52 35.0 Comparative Example 2 Molded carbon black 1.40 31.4 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━ Table 1 Examples and comparative examples (continued) 分散 Dispersion index (D %) Environmental pollution ────────────────────────────── Example 1 99.2 None Comparative example 1 95.4 Large pollution Comparative example 2 99.3 Pollution Small ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━

[0049]

As is clear from the comparison between the examples and the comparative examples, the rubber composition produced by using the carbon black molded by pressure according to the present invention has high dispersibility, low loss and low heat generation. Show. Further, the balance between these physical properties can be controlled by the density of the molded body. Further, since the carbon black to be mixed forms a molded product having a very small powdering rate and is further packaged, dust contamination can be reduced to almost zero, and the working environment is remarkably improved.

Further, the problems of reducing transportation and storage costs and preventing environmental pollution due to generation of dust during rubber kneading, which have been major problems in the use of carbon black, have been solved. It is extremely useful.

[Brief description of the drawings]

FIG. 1 shows a molding machine and a series of molding operations that can be used in the present invention.

[Explanation of symbols]

 1 Hydraulic cylinder (upper) 2 Cylinder 3 Vacuum chamber 4 Upper punch

Claims (6)

[Claims] 1. A pressure-molded carbon black compound for rubber compounding, which is coated. 2. The pressure-molded carbon black compound for rubber compounding according to claim 1, wherein the coating comprises a heat-shrinkable material. 3. The pressure-molded carbon black compound for rubber compounding according to claim 1, wherein the coating is made of a material which is dissolved or mixed with rubber. 4. The pressure-molded carbon black molded article for rubber compounding according to claim 1, wherein the volume is 1 cc or more. 5. A carbon black molded under pressure at 5 to 1000 ° f / cm ² in 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and diene synthetic rubber. A carbon black-containing rubber composition obtained by mixing, mixing and dispersing 30 to 150 parts by weight of a carbon black pressure-molded product. 6. The density ρ of carbon black molded by pressure.
(G / cc): ρ = 8.190 × 10 ⁻³ D−3.824 × 10 ⁻³ L +
0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 or less (where D (nm) is the arithmetic average particle diameter of carbon black by an electron microscope, and L (ml / 100 g) is DB
P oil absorption. 6. The carbon black-containing rubber composition according to claim 5, wherein