JP6986935B2 - Surface-treated carbon black and its manufacturing method - Google Patents

Description

The present invention relates to surface-treated carbon black and a method for producing the same.

Conventionally, it has been known to use a hydrazide compound in a rubber composition for the purpose of improving characteristics such as low fuel consumption and low heat generation of a pneumatic tire made of a rubber composition (Patent Documents 1 and 2). ..

Japanese Unexamined Patent Publication No. 2017-95663 Japanese Patent Publication No. 2014-501827

On the other hand, in the market, rubber compositions that are more excellent in scorchability (processability) and tires (vulcanized rubber) made from the rubber composition are required to have lower heat generation properties. The vulcanized rubber obtained from the rubber composition as in the above patent document has room for improvement in its properties.

The present invention has been made in view of the above circumstances, and is a surface-treated carbon black and its production which can obtain a vulcanized rubber having low heat generation and a rubber composition capable of suppressing deterioration of scorch property. The purpose is to provide a method.

The present invention relates to a surface-treated carbon black in which the surface of the carbon black is treated with a dihydrazide compound.

The present invention also relates to a method for producing the surface-treated carbon black, which comprises a step of treating the surface of the carbon black with the dihydrazide compound.

The details of the action mechanism of the effect in the surface-treated carbon black according to the present invention are unknown, but it is presumed as follows. However, the present invention does not have to be construed as being limited to this mechanism of action.

In the surface-treated carbon black of the present invention, the surface of the carbon black is treated with a dihydrazide compound. By treating the surface of carbon black with a dihydrazide compound in advance, the dihydrazide compound can be efficiently attached (bonded) to the surface of carbon black (the few functional groups present on the surface (for example, carboxyl group)). It is estimated to be. In particular, when an aqueous solution containing the dihydrazide compound is used, the contact efficiency between carbon black and the dihydrazide compound is increased, so that it is presumed that the dihydrazide compound can be attached (bonded) more efficiently.

By using such surface-treated carbon black as a raw material for a rubber composition for tires, the carbon-carbon double bond portion of the dihydrazide compound present in the surface-treated carbon black can be combined with the radical of the rubber component (polymer). Since it is presumed that the vulcanized rubber can be bonded to the rubber component (polymer) by the reaction or the reaction associated with the sulfur cross-linking, the obtained vulcanized rubber has excellent low heat generation.

By using the surface-treated carbon black as described above as a raw material for the rubber composition for tires, it is presumed that the unreacted dihydrazide compound does not promote the vulcanization reaction. The decrease (deterioration) can be suppressed.

<Surface treatment carbon black>
In the surface-treated carbon black of the present invention, the surface of the carbon black is treated with a dihydrazide compound.

As the carbon black, for example, in addition to carbon black used in the ordinary rubber industry such as SAF, ISAF, HAF, FEF, and GPF, conductive carbon black such as acetylene black and Ketjen black can be used. .. The carbon black may be granulated carbon black or ungranulated carbon black, which is granulated in consideration of its handleability in the ordinary rubber industry. Carbon black may be used alone or in combination of two or more.

The carbon black, from the viewpoint of improving the reinforcing property of the vulcanized rubber, DBP absorption amount (dibutyl phthalate absorption) ^is preferably at 80 cm 3/100 g or ^more, more preferably 110 cm 3/100 g or more ^and is preferably 180cm 3/100 g or ^less, and more preferably less 140cm 3 / 100g.

The carbon black, from the viewpoint of improving the low heat generation property of the vulcanized rubber, the nitrogen adsorption specific surface area, is preferably ^{30 m} 2 / g or more, more preferably ^{50 m} 2 / g or more, 100 m ² / It is more preferably g or more, more preferably 250 m ² / g or less, ^{more preferably 200 m 2} / g or less, still more preferably 180 m ² / g or less.

The dihydrazide compound is a compound having _two hydrazide groups (-CONNHN 2) in its molecule, and is, for example, isophthalic acid dihydrazide, terephthalic acid dihydrazide, azelaic acid dihydrazide, adipic acid dihydrazide, succinic acid dihydrazide, eicosanite dihydrazide, and the like. Examples thereof include 7,11-octadecazien-1,18-dicarbohydrazide. Among these, the dihydrazide compound is preferably isophthalic acid dihydrazide or adipic acid dihydrazide, and more preferably isophthalic acid dihydrazide. The dihydrazide compound may be used alone or in combination of two or more.

The dihydrazide compound is preferably used in an aqueous solution containing the dihydrazide compound from the viewpoint of increasing the contact efficiency with carbon black. The medium in the aqueous solution is a medium containing water as a main component, such as ion-exchanged water, distilled water, and industrial water, but may be, for example, water containing an organic solvent. The medium may be used alone or in combination of two or more.

The ratio of the dihydrazide compound in the aqueous solution containing the dihydrazide compound is preferably 0.1% by weight or more, preferably 0.3% by weight or more, from the viewpoint of improving the low heat generation property of the vulture rubber. Is more preferably 0.5% by weight or more, still more preferably 1.5% by weight or more, and the viewpoint of sufficiently dissolving the dihydrazide compound in the medium, and the rubber composition. From the viewpoint of suppressing (preventing) deterioration (deterioration) of the scorch property of the substance, it is preferably 30% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight or less.

Further, the aqueous solution containing the dihydrazide compound preferably has a temperature of 60 ° C. or higher, more preferably 70 ° C. or higher, and more preferably 80 ° C. or higher, from the viewpoint of sufficiently dissolving the dihydrazide compound in the medium. It is more preferably 90 ° C. or higher, and from the viewpoint of safety, it is preferably below the boiling point of the medium.

In the surface-treated carbon black, the amount of the dihydrazide compound used (surface treatment amount) is 0.02 part by weight or more with respect to 100 parts by weight of the carbon black from the viewpoint of improving the low heat generation property of the vulture rubber. It is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, further preferably 0.2 parts by weight or more, and a rubber composition. From the viewpoint of suppressing (preventing) the deterioration (deterioration) of the scorch property, it is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and further preferably 5 parts by weight or less. It is more preferably less than parts by weight.

<Manufacturing method of surface-treated carbon black>
In the method for producing the surface-treated carbon black of the present invention, the surface treatment method is not particularly limited, but for example, while stirring (flowing) the carbon black in a mixer or a blender, 1) the dihydrazide. For a method of adding a compound or an aqueous solution containing the compound and stirring the mixture, 2) a method of spraying the aqueous solution containing the dihydrazide compound with a sprayer such as a spray, and 3) a carbon black granulation step. Examples thereof include a method of adding the dihydrazide compound to the water to be used for treatment. As the surface treatment method, a spray treatment method is preferable from the viewpoint of uniform coating.

In the surface treatment, the treatment temperature is not limited at all, but when an aqueous solution containing the dihydrazide compound is used, the temperature of the aqueous solution is preferably 60 ° C. or higher, preferably 70 ° C. or higher, from the viewpoint of suppressing the precipitation of the dihydrazide compound. The temperature is more preferably ° C. or higher, more preferably 80 ° C. or higher, further preferably 90 ° C. or higher, and from the viewpoint of safety, the temperature is preferably lower than the boiling point of the medium. The treatment time depends on the amount of carbon black used and cannot be unequivocally stated, but is usually about 3.0 to 5.0 minutes.

The surface-treated carbon black obtained by the above-mentioned surface treatment can be used without a drying step such as natural drying or forced drying from the viewpoint of shortening the mixing time, but after the above-mentioned surface treatment step. Can also be provided with the drying step.

<Rubber composition>
In the present invention, the rubber composition can be prepared by using the surface-treated carbon black. Examples of the raw material of the rubber composition include rubber and various compounding agents usually used in the rubber industry.

Examples of the rubber include synthetic diene rubber such as natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), and nitrile rubber (NBR). Rubber is mentioned. The rubber may be used alone or in combination of two or more.

With respect to 100 parts by weight of the rubber component in the rubber composition, the dihydrazide compound in the surface-treated carbon black is preferably 0.01 part by weight or more from the viewpoint of improving the low heat generation property of the sulfide rubber. , 0.03 parts by weight or more, more preferably 0.05 parts by weight or more, further preferably 0.1 parts by weight or more, and the scorch property of the rubber composition. From the viewpoint of suppressing (preventing) the decrease (deterioration), it is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, further preferably 3 parts by weight or less, and 1.5 parts by weight. The following is even more preferable.

The surface-treated carbon black is preferably 30 to 100 parts by weight, preferably 35 to 80 parts by weight, with respect to 100 parts by weight of the rubber component in the rubber composition, from the viewpoint of improving the reinforcing property of the vulcanized rubber. Is more preferable, and 40 to 70 parts by weight is further preferable.

Examples of the various compounding agents include sulfur-based vulcanizing agents, vulcanization accelerators, antiaging agents, silica, silane coupling agents, zinc oxide, methylene acceptors and methylene donors, stearic acid, and vulcanization accelerating aids. , Vulcanization retarder, organic peroxide, softeners such as wax and oil, processing aids and the like.

The sulfur as the sulfur-based vulcanizing agent may be ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used. The sulfur-based vulcanizing agent may be used alone or in combination of two or more.

The sulfur content is preferably 0.3 to 6.5 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. If the sulfur content is less than 0.3 parts by weight, the crosslink density of the vulcanized rubber is insufficient and the rubber strength etc. is lowered, and if it exceeds 6.5 parts by weight, both heat resistance and durability are particularly high. Getting worse. In order to secure good rubber strength of vulcanized rubber and further improve heat resistance and durability, the sulfur content is 1.0 to 5.5 with respect to 100 parts by weight of the rubber component in the rubber composition. It is more preferably a part by weight.

The vulcanization accelerator may be an ordinary vulcanization accelerator for rubber, and may be a sulfur amide-based vulcanization accelerator, a thiuram-based vulcanization accelerator, a thiazole-based vulcanization accelerator, or a thiourea-based vulcanization accelerator. , Guanidin-based vulcanization accelerator, dithiocarbamate-based vulcanization accelerator and the like. The vulcanization accelerator may be used alone or in combination of two or more.

The content of the vulcanization accelerator is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition.

The anti-aging agent may be an ordinary anti-aging agent for rubber, and may be an aromatic amine-based anti-aging agent, an amine-ketone-based anti-aging agent, a monophenol-based anti-aging agent, a bisphenol-based anti-aging agent, or a polyphenol-based anti-aging agent. Examples thereof include anti-aging agents, dithiocarbamate-based anti-aging agents, and thiourea-based anti-aging agents. The anti-aging agent may be used alone or in combination of two or more.

The content of the antiaging agent is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition.

The method of blending (adding) the surface-treated carbon black, the rubber, and the various compounding agents is, for example, a method of kneading using a kneading machine used in a normal rubber industry such as a Banbury mixer, a kneader, and a roll. Can be mentioned.

The method of kneading is not particularly limited, but for example, a method of adding and kneading components other than the vulcanization-based components such as a sulfur-based vulcanizing agent and a vulcanization accelerator in an arbitrary order, and a method of simultaneously adding and kneading. Further, a method of adding all the components at the same time and kneading them can be mentioned. Further, the number of kneading may be once or a plurality of times. The kneading time varies depending on the size of the kneading machine used and the like, but is usually about 2 to 5 minutes. The discharge temperature of the kneader is preferably 120 to 170 ° C, more preferably 120 to 150 ° C. When the vulcanizing component is contained, the discharge temperature of the kneader is preferably 80 to 110 ° C, more preferably 80 to 100 ° C.

The rubber composition containing the surface-treated carbon black of the present invention has scorch resistance. Further, the vulcanized rubber obtained from the rubber composition has low heat generation, and is therefore suitable for pneumatic tires.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Raw materials used)
a) Dihydrazide compound: Isophthalic acid dihydrazide (manufactured by Japan Finechem Company, Inc.)
b) Carbon black (1): "SEAST 300 (HAF-LS)" (nitrogen adsorption specific surface area ^84m 2 / g, DBP absorption 75 cm ^3/100 g) (manufactured by Tokai Carbon Co., Ltd.)
c) Natural rubber: "RSS # 3"
d) Zinc oxide: "Zinc oxide 2 types" (manufactured by Mitsui Mining & Smelting Co., Ltd.)
e) Stearic acid: "Beads stearic acid" (manufactured by NOF CORPORATION)
f) Sulfur: "5% oil-containing fine powder sulfur" (manufactured by Tsurumi Chemical Industry Co., Ltd.)
g) Vulcanization accelerator (A): N-cyclohexyl-2-benzothiazolesulfenamide, "Sunceller CM-G" (manufactured by Sanshin Chemical Industry Co., Ltd.)
h) Vulcanization accelerator (B): N-tert-butyl-2-benzothiazolyl sulfenamide, "Noxeller NS-P" (manufactured by Ouchi Shinko Kagaku Co., Ltd.)

<Example 1>
<Manufacturing of surface-treated carbon black 1>
Isophthalic acid dihydrazide as a dihydrazide compound was measured in a predetermined amount of carbon black (1) so that the weight ratio of the carbon black / dihydrazide compound became the weight ratio shown in Table 1. Distilled water was added so that the concentration of the dihydrazide compound was 0.5% by weight based on the total amount of the measured dihydrazide compound, and the mixture was heated and mixed to 60 ° C. A spray gun while stirring the entire amount of the obtained aqueous solution (0.5% by weight) containing the dihydrazide compound in the above-mentioned predetermined amount of carbon black (1) with a mixer (“SMV-20” manufactured by Kawata Co., Ltd.). The surface-treated carbon black 1 was produced by spraying with. The blending ratio in Table 1 is shown in parts by weight (phr) when the total amount of the rubber components contained in the rubber composition shown in Table 2 is 100 parts by weight.

<Manufacturing of rubber composition and unvulcanized rubber composition>
The surface-treated carbon black 1 obtained above and each of the raw materials shown in Table 2 (components excluding sulfur and vulcanization accelerator) are dry-mixed using a rubbery mixer (kneading time: 3 minutes, discharge temperature: 150). A rubber composition was produced by heating at ° C.). Next, sulfur, the vulcanization accelerator (A) and the vulcanization accelerator (B) shown in Table 2 are added to the obtained rubber composition, and dry mixing (kneading time: 1 minute, discharge) using a Banbury mixer. The temperature was 90 ° C.) to produce an unvulcanized rubber composition. The blending ratio in Table 2 is shown in parts by weight (phr) when the total amount of the rubber components contained in the rubber composition is 100 parts by weight. Further, the weight portion of the surface-treated carbon black in Table 2 represents only the total weight of the carbon black and the dihydrazide compound.

<Examples 2 to 6>
<Manufacturing of surface-treated carbon black>
Surface-treated carbon blacks 2 to 6 were produced by the same operations as in Example 1 except that the weight ratio of the carbon black / dihydrazide compound and the concentration of the aqueous solution containing the dihydrazide compound were changed as shown in Table 1. ..

<Manufacturing of rubber composition and unvulcanized rubber composition>
A rubber composition and an unvulcanized rubber composition were produced by the same method as in Example 1 except that the type of surface-treated carbon black was changed as shown in Table 2.

<Comparative Examples 1 and 2>
A rubber composition was produced by dry-mixing each of the raw materials (components excluding sulfur and vulcanization accelerator) shown in Table 2 using a Banbury mixer (kneading time: 3 minutes, discharge temperature: 150 ° C.). .. Next, sulfur, the vulcanization accelerator (A) and the vulcanization accelerator (B) shown in Table 2 are added to the obtained rubber composition, and dry mixing (kneading time: 1 minute, discharge) using a Banbury mixer. Temperature: 90 ° C.) to produce an unvulcanized rubber composition.

The unvulcanized rubber compositions obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 2.

<Evaluation of scorch resistance>
The evaluation of scorch resistance is based on JIS K6300, and the unvulcanized rubber composition is preheated at 125 ° C. for 1 minute using a rotary Mooney measuring machine manufactured by Toyo Seiki Seisakusho Co., Ltd., and then has a minimum viscosity of Vm. The time t5 required for the Mooney unit to rise was measured and displayed as an index with the value of Comparative Example 1 as 100. The larger the index, the longer the scorch time and the better the scorch resistance.

A vulcanized rubber was produced by vulcanizing the unvulcanized rubber compositions obtained in the above Examples and Comparative Examples at 150 ° C. for 30 minutes. The obtained vulcanized rubber was evaluated as follows. The evaluation results are shown in Table 2.

<Evaluation of heat generation>
For the evaluation of heat generation, a viscoelasticity tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used to measure the loss coefficient tan δ under the conditions of static strain 10%, dynamic strain ± 2%, frequency 50 Hz, and temperature 60 ° C. The value of Comparative Example 1 was set as 100 and displayed as an exponent. The smaller the index, the less likely it is to generate heat, and the better the low heat generation.

Claims (3)

It is a manufacturing method of surface-treated carbon black.
A method for producing surface-treated carbon black, which comprises a step of treating the surface of granulated carbon black with an aqueous solution containing a dihydrazide compound . The method for producing surface-treated carbon black according to claim 1, wherein the ratio of the dihydrazide compound in the aqueous solution containing the dihydrazide compound is 0.1 to 30% by weight. The method for producing surface-treated carbon black according to claim 1 or 2, wherein the treatment step is a spray treatment step .