JPS62104850A - Rubber composition - Google Patents

Abstract

PURPOSE:A rubber composition, obtained by blending rubber with carbon black having selective characteristic, having both low heat build-up and high reinforcing properties and utilizable for automotive tires, conveyor belts, etc. CONSTITUTION:A rubber composition obtained by blending carbon black having (i) 35-75m<2>/g nitrogen adsorption specific surface area (N2SA) and >=100ml/100DBP oil absorption (DBP), (ii) >=3.5 value of parameter, expressed by the formula and constituted of a half width (Dst) of aggregate distribution measured by a centrifugal settling method, DBP and N2SA and (iii) >=0.95 value of ratio (D peak/D50) of the mode diameter (D peak) of the aggregate distribu tion to the average aggregate diameter (D50) measured by the centrifugal settling method in an amount of 30-200pts.wt. with 100pts.wt. rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rubber composition for tires that has both low heat build-up and high reinforcing properties by blending carbon black with selective properties.

[Prior art]

Regarding the rubber reinforcing performance of carbon black, it was conventionally thought that only its particle size and stracture were the dominant factors. Therefore, the nitrogen adsorption specific surface area (NASA), which is an index of particle size, and the iodine adsorption ff1 (
DBP oil absorption (D
BP) etc. have been mainly considered important as the colloidal properties of carbon bras. That is, in order to obtain a rubber composition with high reinforcing properties, it has been common practice to blend carbon black (with small particle size and large struture) with large values of N25A, IA, and DIIP.

However, blending such carbon black is disadvantageous in terms of low heat build-up.

On the other hand, if carbon black with a large particle size is blended in order to obtain low heat build-up, the reinforcing properties will deteriorate. For this reason, it has been considered extremely difficult to achieve both reinforcing properties and low heat generation properties, which are contradictory properties.

In recent years, other selective properties have been added to carbon black in addition to properties such as Nz5A11A and DBP.
Attempts have been made to achieve both of these contradictory performances. For example, as new selective properties to be imparted, there are those that focus on tinting power (Japanese Patent Publication No. 13461/1982) and those that focus on the Stokes mode diameter of particle aggregate distribution (Japanese Patent Application Laid-open No. 86663/1982). Official gazette, Japanese Patent Publication No. 5
No. 9-86641 (Ig).

In addition, there are prior art techniques such as one that focuses on the surface activity of carbon black (Japanese Unexamined Patent Publication No. 60-42439).

However, these prior art techniques have focused on improving reinforcement performance, and the improvement of dynamic performance has been limited to adjustment by particle size, which has been commonly done in the past.

Therefore, from the standpoint of achieving both dynamic performance and reinforcing performance, it was not fully satisfactory.

[Purpose of the invention]

The object of the present invention is to provide a rubber composition that has both high reinforcing properties and low heat generation properties, and the rubber composition of the present invention can be used for automobile tires (passenger car tires, bus/trunk tires, etc.). In addition to being used as a rubber material for carcass, tread, side tread, undertread, etc., it is also used in industrial products such as conveyor belts and air springs.

[Structure of the invention]

Therefore, the present invention provides nitrogen adsorption specific surface area<NzS^)3
5~7! M/g, DBP oil absorption 100ml/g 1
Carbon black in the characteristic range of 00 or more,
A parameter (ΔDst-DBP) consisting of the half-width of aggregate distribution (ΔDst) by centrifugal sedimentation method, onp oil absorption amount, and nitrogen adsorption specific surface area (NSA).
・The value of (N2SA) -' is 3.5 or more and the diameter of the most frequently occurring aggregate distribution by centrifugal sedimentation method (D1'-
Ratio of average aggregate diameter (D50) [1 hea/Ds
. Carbon black with a value of 0.95 or more is used as rubber 1
The rubber composition is characterized in that it is blended in an amount of 30 to 200 parts by weight with respect to 00 parts by weight.

Hereinafter, the configuration of the present invention will be explained in detail.

The carbon black used in the present invention is as follows fa) to f
It has the characteristics c).

(al Nitrogen adsorption specific surface area (NtSA) 35-75
rrf/g1, DBP adsorbed oil 100ml/10
Must be in the characteristic region of 0 g or more.

This is because if the nitrogen adsorption specific surface area is less than 35 m/g, the reinforcing properties will deteriorate, while if it exceeds 75 g/g, it will be unfavorable in terms of heat generation.

Further, if the DBP oil absorption amount is less than 1/100g of Loom, the desired high reinforcing properties cannot be obtained.

(bl Half-width of aggregate distribution by centrifugal sedimentation method (ΔD
s t), DBP oil absorption and nitrogen adsorption specific surface area (NA
SA) and the parameter (ΔDst
・DBP)I/2・(NzSA)-' value is 3.5 or more.

This is because if this value is less than 3.5, the desired low heat generation property cannot be obtained.

(C) Ratio Dbeak/Ds of the most frequently occurring diameter (Dhi'l) and the average diameter (0,.) of the aggregate distribution obtained by centrifugal sedimentation. The value of is 0.95 or more.

This is because if this value is less than 0.95, it is not possible to obtain the desired high reinforcing property while maintaining low heat generation property.

The centrifugal sedimentation method referred to here is a measurement using a disk centrifuge manufactured by Joyce Leble, which takes advantage of the fact that particles with a large Stokes diameter settle quickly and determines how quickly the particles settle. This is a method to find the size.

FIG. 1 shows an example of an aggregate distribution curve showing the aggregate diameter and ΔDst of carbon black. In the figure, m is an aggregate distribution curve. By creating this curve, ΔDs
t can be easily determined. The area of the shaded area is 50% of the total area surrounded by the aggregate distribution curve.

The rubber composition of the present invention contains 30 parts by weight of carbon black having the properties of the above (al to (C1) to 100 parts by weight of rubber.
~200 parts by weight.

As the rubber, various commonly used rubbers such as natural rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, synthetic polyisoprene rubber, and butyl rubber can be used.

If the blending ratio of carbon black is less than 30 parts by weight per 100 parts by weight of rubber, the desired highly reinforcing rubber composition will not be obtained, while if it exceeds 200 parts by weight, the desired low heat build-up rubber will not be obtained. Since the composition cannot be obtained, 30~
Must be within 200 parts by weight.

In addition to carbon black, the rubber composition of the present invention may optionally contain, for example, a vulcanizing agent such as sulfur, a vulcanization accelerator, a vulcanization accelerating aid, an anti-aging agent, a tackifier, a softening agent, It may also contain fillers and the like.

EXAMPLES The effects of the present invention will be specifically explained below with reference to Examples and Comparative Examples.

Examples and Comparative Examples Various rubber compositions (11k11~
Kan 7) was produced.

The properties of each carbon black used in this case are shown in Table 2 below. In addition, the characteristic values are based on the following measurement methods (1) to (5).

Chapter 1 Table (1) Nitrogen adsorption specific surface area.

ASTM-D3037-78”5 standard
Methods of Testing Carbo
n Black-5surface Area b
y Nitrogen8dsorpt on″Met
By hod C.

(2) Amount of iodine adsorption.

JIS K 6221 (1982) r Carbon black test method for rubber J6.1. ．． According to 1.

+3+DBP oil absorption.

JIS K 6221 (1982) ``Test method for carbon black for rubber'' 6.1゜2 fIIA method.

(4) Stokes median diameter of particle aggregate distribution (OSO
), maximum frequency diameter (Di'-ri), distribution half-width (ΔD
□).

Measurements were performed by centrifugal sedimentation using a disk centrifuge manufactured by Joyce Lebre. The outline of the measurement method is as follows.

Carbon black, which had been dried and precisely weighed according to JIS K 6221 (1982) 5 method, was added to a 20 volume % aqueous solution of ethanol to give a carbon black concentration of 0.005.
After converting it to weight percent, it was sufficiently dispersed using ultrasonic waves to prepare a sample. Increase the rotation speed of the disk centrifuge to 600 Orp.
After adding 10IllI2 of spin solution (distilled water), add 0.5mA' buffer solution (20vo I!%).
Ethanol water? Inject 8 aqueous liquids. Then, sample solution 0
．． 5~0.75m/! was added with a syringe to start centrifugal sedimentation, and an aggregate distribution curve was created by photoelectric precipitation. D
5°, D peak, ΔD5. was determined from Figure 1.

Table 2 shows examples and comparative examples of the present invention.

Carbon bras having the properties shown in Table 2 were mixed according to Table 1, kneaded, and vulcanized in 30 portions at 150'C to obtain a vulcanizate. Table 3 shows the measurement results of various physical properties of the vulcanizate thus obtained.

Among various physical properties of the rubber, the degree of heat generation was measured using Kei TM D623-78A. In addition, tan δ was measured using a viscoelastic spectrometer (Iwaki Seisakusho (naked)) under the following conditions: Temperature: 20°C 5 Strain rate 10 ± 2% 1 Frequency: 2011z All other rubber physical properties were measured under the following conditions. Compliant with JIS K 6301r General Rubber Test Methods.

(Left space on wooden page) Various rubber physical properties were measured for a rubber composition obtained by vulcanizing the compound blended as described above at a temperature of 150° C. for 30 minutes. The results are shown in Table 3.

(Margins below this page) As can be seen from Table 3, columns 1 and 2 are examples of the present invention.
shows the same hardness and 300% modulus as when N11L7's 11AF class carbon black is blended, and also exhibits high rebound resilience, low heat generation, and low loss coefficient that exceeds the case where N11L7's FEF class carbon black is blended. There is.

N13, which is a comparative example, is (ΔDst −DBP)”
This is an example in which carbon black is blended whose "-(N2SA)-' value satisfies the value of the present invention, but the Dheat/Ds value is less than the value of the present invention. Therefore, this rubber composition The product is Example 11 containing FEF grade carbon black.
Although it exhibits a low heat build-up that exceeds that of h6, it falls short of the 300% modulus of fish 7, which is an example of IIAF class carbon black.

Comparative example No. 5 has a D peak/D50 value that satisfies the value of the present invention, but (ΔDst −DBP)””・
This is an example in which carbon black whose (N zSA) -' value is less than the value of the present invention is blended. Therefore, this rubber composition exhibits a 300% modulus higher than that of Inhibi 4, which is an example of compounding carbon black with a similar nitrogen adsorption specific surface area and DBP oil absorption, and II A F
Rubber composition containing grade carbon black, light 7 or higher, 3
Although it shows 00% modulus, regarding low heat generation,
It is not as good as the rubber compositions of No. 6, which is an example in which FEF grade carbon black is blended, and No. 1 and No. 2, which are examples of the present invention.

〔Effect of the invention〕

As explained above, the rubber composition of the present invention has the following characteristics: the ratio of the D peak of the particle aggregate distribution of the blended carbon black to 050;
Since the value of -' is specified, it is possible to achieve both reinforcing properties and low heat generation properties, which were conventionally considered to be contradictory. That is, it has a reinforcing property equivalent to that when HAP grade carbon black is blended, and has a low heat generation property that exceeds that when FEF grade carbon black is blended.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an aggregate distribution curve. m... Aggregate distribution curve.

Claims (1)

[Claims] Nitrogen adsorption specific surface area (N_2SA) 35-75m^2/g
, carbon black in the characteristic range of DBP oil absorption of 100 ml/100 g or more, and a parameter consisting of the half-width of aggregate distribution (ΔDst) by centrifugal sedimentation, DBP oil absorption, and nitrogen adsorption specific surface area (N_2SA) (ΔDst・DBP)＾1＾/＾2・(N_2SA)＾
-^1 value is 3.5 or more, and the most frequently occurring diameter (D peak) of the agglomeration distribution by centrifugal sedimentation method and the average aggregate diameter (
D_5_0) ratio Dpeak/D_5_0 value is 0.9
A rubber composition characterized in that 30 to 200 parts by weight of carbon black having a molecular weight of 5 or more is blended with respect to 100 parts by weight of rubber.