JPH05220736A - Rubber mixing method - Google Patents

Abstract

PURPOSE:To provide the rubber mixing method for preventing oil slip and improving the quality and performance of a rubber composition. CONSTITUTION:When carbon black with the diameter of 19 namometer (UM) or less of 60-90 pts.wt. and oil of 10-50 pts.wt. are added and mixed with unvulcanized rubber of 100 pts.wt., first carbon black is added to the unvulcanized rubber and agitated and mixed until BIT is formed, and then oil is added continuously little by little or added dividedly and intermittently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a 19-nanometer (n
m) A method for mixing rubber in which carbon black having the following small particle diameter is mixed with oil.

[0002]

2. Description of the Related Art Generally, as is well known, rubber compositions used for producing various rubber products have mechanical properties such as hardness, tensile strength, modulus and abrasion resistance of rubber. A large amount of carbon black is blended as a reinforcing agent in order to improve the rubber composition, and a large amount of oil is blended in order to impart plasticity to the rubber to improve mixing and dispersion of the blended chemicals and improve workability.

In this case, in general, the particle size of carbon black tends to be reduced in order to improve wear resistance. However, when a carbon black having a small particle size of 19 nanometers (hereinafter abbreviated as nm) or less is obtained, 50 to 90 parts by weight of this carbon black is mixed with 100 parts by weight of rubber, and then 10 to 50 parts by weight of oil is mixed. , The mixing machine such as Banbury mixer causes rotor slip (referred to as oil slip) due to the oil, so that the mixing could not be performed.

Therefore, a mixing method as shown in FIG. 2 has been conventionally used. That is, FIG. 2 is a graph showing changes over time in the torque of the stirrer in the conventional rubber compounding. In FIG. 2, point a indicates the time of addition of rubber, point b indicates the time of addition of carbon black, and point c indicates the time of addition of oil. The torque rises due to the addition of the rubber at the point a, and then the torque sharply rises due to the addition of the carbon black at the point b, but once decreases slightly and then rises gradually again. In the past, oil slip was prevented by adding oil before point BIT in the course of this tokule gradually rising, that is, before the carbon black was completely dispersed. However, this method has limitations in improving the quality and performance of the obtained rubber composition.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber mixing method capable of preventing oil slip and improving the quality and performance of a rubber composition.

[0006]

The object of the present invention is to provide 60 to 90 parts by weight of carbon black having a particle size of 19 nm or less and 10 to 50 parts by weight of oil to 100 parts by weight of unvulcanized rubber. When adding and mixing, it is achieved by first adding the carbon black to the unvulcanized rubber and stirring and mixing until BIT comes out, and then continuously adding the oil little by little to the mixture or intermittently adding it in portions. can do.

In the present invention, BIT (Black in corpo
The rate time) means the time point at which the torque of the stirrer is generated, which means the end of dispersion of the carbon black when the carbon black is put into the unvulcanized rubber and the stirrer is mixed. Specifically, in the graph of FIG. 3 showing the change in torque over time when the rubber is stirred and mixed, the rubber of the a point is blended and the carbon black is blended at the b point, whereby the torque of the stirrer is rapidly increased. However, this torque once decreases and then slightly rises and decreases to produce a small peak P, which is the point at which the dispersion of carbon black is completed, and this point is called BIT.

According to the present invention, 50 to 90 parts by weight of carbon black and 10 to 10 parts of oil are added to 100 parts by weight of unvulcanized rubber.
It is premised that 50 parts by weight is compounded. In such a mixing operation, first, 50 parts by weight or more of carbon black is added to unvulcanized rubber, stirring and mixing are continued until BIT comes out, and then 10 parts by weight or more of oil is continuously added little by little. Alternatively, intermittent addition of oil can prevent oil slip and provide a high-quality rubber composition having high carbon black microdispersion.

FIG. 1 is a graph showing changes in torque with time in the mixing method of the present invention. In FIG. 1, a, b
Similarly to FIG. 2, c and c respectively indicate the addition points of rubber, carbon black and oil. As shown in FIG. 1, rubber is added at point a and then carbon black is added at point b. By the addition of this carbon black, the torque of the stirrer rises rapidly, and BIT is generated, which once decreases with the progress of stirring and mixing, and then slightly increases and decreases again. At point c where this BIT occurs, 10 parts by weight or more of oil is divided into small portions and the first small amount of oil is added. By the addition and mixing of the oil, the torque of the stirrer drops sharply and then rises again, so the second oil is added during this rising process. Thereafter, this is repeated to complete the addition of the predetermined amount of oil.

FIG. 1 shows an example in which the oil is divided and added little by little, but in the method of the present invention, the oil can be continuously added little by little. In this case the torque, as in Figure _{1, c 1, c 2,} c 3, without forming the peak of each ──────C _n, draw a smooth curve. The number of additions and the addition rate of this oil differ depending on the amount of carbon black or oil to be added, but it is preferable to add all the oil at least 6 times in a substantially even manner, or an example of a 3.5-liter lab mixer. Then, it is preferable to mix at an addition rate of 10 to 30 g / min.

The total amount of carbon black may be added to the rubber at once, or may be added in portions. In the above method of the present invention, natural rubber, polybutadiene rubber (BR), styrene-butadiene copolymer rubber (S
Various rubbers such as BR), chloroprene rubber, ethylene-propylene-diene terpolymer rubber (EPDM), and nitrile rubber can be used and are not particularly limited.

In the present invention, since carbon black having a particle size of 19 nm or less is used, the effect of improving the quality and performance of the rubber composition can be enhanced.
Further, the oil is not particularly limited, and commonly used paraffin oil, aromatic oil, naphthene oil and the like can be used. In the method of the present invention, in addition to the above-mentioned carbon black and oil, various rubber compounding agents which are usually compounded in a rubber composition, for example, sulfur, a vulcanization accelerator, an antioxidant, zinc white, stearic acid and the like are appropriately compounded. There is no difference in what you do.

[0013]

【Example】

Example Banbury mixer (3.5 liter lab mixer)
100 parts by weight of SBR (Toughden 4003 manufactured by Asahi Kasei Co., Ltd.) was added, and 90 parts by weight of carbon black (SAF (SEAST 9, N211) manufactured by Tokai Carbon Co., Ltd. was added while mixing this. About 7 parts by weight of aromatic oil (Kyoseki Process X-140) was added and mixed in 7 parts by weight at intervals of about 2 minutes.

The abrasion resistance of the obtained rubber composition, 30
The 0% modular and tensile strength were measured by the following methods. The results are shown in Table 1. Abrasion resistance : The amount of abrasion (g) was measured under the following conditions using a Lambourn abrasion tester according to the method described in BS903 PartA9 D method.

Measurement conditions: slip = 25%, load = 5
kg, time = 4 minutes, temperature = 23 ° C., grindstone = K80 300% modulus and tensile strength : JIS K630
The measurement was performed according to the method specified in 1. Comparative Example Using the same amount of SBR, carbon black, and oil as in the method of Example, carbon black was added to SBR and stirred, and the total amount of oil (50 parts by weight) was added for 5 minutes before BIT appeared. Mix with stirring. The abrasion resistance and 300% modulus of the obtained rubber composition were measured by the above-mentioned methods, and the results are shown in Table 1.

[0016] It can be seen from Table 1 that the method of the present invention of the examples can simultaneously improve the 300% modulus and the tensile strength as compared with the method of the comparative example, and has a small wear amount and excellent wear resistance. It can be seen that the reinforcing effect is improved.

[0017]

According to the rubber mixing method of the present invention, carbon black of 50 to 90 is added to 100 parts by weight of unvulcanized rubber.
When mixing 10 parts by weight of oil and 10 to 50 parts by weight of oil, first add carbon black to unvulcanized rubber and BIT
The oil is prevented from slipping and the reinforcing property of the carbon black can be improved because the oil is intermittently added to the above mixture little by little or continuously added in small portions.

[Brief description of drawings]

FIG. 1 is a graph showing changes over time in the torque of a stirrer in the mixing method of the present invention.

FIG. 2 is a graph showing changes over time in the torque of the stirrer in the conventional mixing method.

FIG. 3 is a graph showing the change over time in the torque of the stirrer for explaining the BIT.

[Explanation of symbols]

a When compounding rubber b When compounding carbon black c When BIT occurs

Claims (1)

[Claims] 1. When 100 to 50 parts by weight of unvulcanized rubber is added and mixed with 60 to 90 parts by weight of carbon black having a particle size of 19 nanometers (nm) or less and 10 to 50 parts by weight of oil, the carbon black is first mixed. Is added to unvulcanized rubber and mixed by stirring until BIT appears, and then oil is continuously added to the mixture little by little or intermittently dividedly added.