JPS5859239A - Vulcanized elastomer composition and tyre - Google Patents

Abstract

PURPOSE:To provide a vulcanized elastomer compsn. having a specified dynamic viscoelastic properties and forming type (tread) with excellent wet grip performance and high-level travelling safety. CONSTITUTION:The vulcanized elastomer compsn. shows a loss factor[tandelta (T)]integrated value SW (equationI) of 5 to higher within the temperature range of -30--15 deg.C as calculated on the basis of temperature distribution curve of loss factor at dynamic strain of 0.5% (frequency: 10Hz, temperature rise rate: 1 deg.C/min) and a loss factor integrated value SR (equation II) of 2.8 or lower within the temperature range of 50-65 deg.C as calculated on the basis of temperature distribution curve of loss factor at the dynamic strain of 0.5% (frequency and temperature rise rate are the same as above). The compsn. is prepared by using high-vinyl butadiene rubber, etc. obtained by solution polymerization process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vulcanized elastomer composition and a tire using the elastomer composition in a tread.

The main properties required for tire rubber include wet grip, rolling resistance (low rolling resistance, heat resistance), abrasion resistance, bending resistance, chipping resistance, group cracking resistance, etc. The following characteristics need to be comprehensively and well-balanced. In particular, in recent years there has been a strong social demand for improving wet grip performance from the viewpoint of reducing transfer resistance from the viewpoint of resource and energy conservation and from the viewpoint of operator safety.

Conventionally, natural rubber, synthetic polyisoprene rubber, high-cis 1,4 polybutadiene rubber, and styrene-butadiene rubber have been mainly used as rubber for tires, but while the former two have low energy loss and low transfer resistance, Glyph performance on wet road surfaces is poor. On the other hand, the latter has high wet grip performance, but has large energy loss and high transfer resistance. Therefore, it is generally recognized that transfer resistance performance and wet grip performance are contradictory performances, and in order to solve this problem, a compounding technique is used that blends the two and selects a harmonious point between both performances.
- Considering the movement of the tread rubber in relation to rolling resistance and wet grip, rolling resistance is due to repetitive motion accompanying tire rotation during running and running, and the frequency of repeated vibration is 10~102H.
z, and its frequency can be converted to a temperature of 60-80°C.

On the other hand, wet grip is considered to be the frictional resistance that occurs in response to the stress received from the road surface when the tire slides on an uneven road surface, and the deformation frequency is 10 to 107 H1, and the surface temperature when sliding is 100 degrees. It is known that the temperature ranges from C to higher.

Therefore, by making the loss characteristics as low as possible in the low frequency region that contributes to transfer resistance performance and as high as possible in the high frequency region that contributes to wet grip performance, both performances, which are considered to be contradictory, can be improved. It is thought that it is possible to do so.

However, at most 9 or 10 people have a high correlation with transfer resistance.
The loss characteristics of viscoelasticity at the frequency of 2H2 can be experimentally measured using various viscoelasticity measurement devices, but it is almost impossible to mechanically measure the loss characteristics at the frequency of 104 to 7Hz, which has a high correlation with wet grip. It can be said that it is almost impossible. .

Conventionally, in the case of viscoelastic polymers, the concept that frequency and temperature are equivalent has been proposed, that is, the value before temperature/time conversion. For butadiene rubber, etc., Ferry et al. proposed the WLF equation, and it has been found empirically that frequency can be converted into temperature in the range from the glass transition temperature Tg to Tg + 100°C (M, L, Wi l
l i ams et al., J. Arrl. Chem.

Soc, 77, 374 (1955)).

However, the glass transition temperatures of natural rubber and emulsion polymerized styrene-butadiene rubber, which are generally used as tire tread rubber, are -70°C and -70°C, respectively.
It has been reported in various literature that the temperature range is around 50°C, and the temperature range in which the WLF formula holds is at most 30 to 50°C.
C, the tire temperature and tire surface temperature during driving as mentioned above are outside this range.
Conventionally, vibration phenomena caused by running and sliding have not been converted from frequency to temperature to be understood as loss characteristics due to temperature dispersion.

Therefore, the inventors purposely deviated from the range in which the W-LF formula holds, but by using the concept of temperature conversion per hour, we calculated high frequency, high temperature, and low frequency when planning wet grip performance. In order to confirm the possibility of conversion to low temperature, we investigated the correlation between the loss characteristics due to temperature dispersion and the actual tire roll resistance performance and wet grip performance. As a result, the wet grip performance has the highest correlation with the logarithm of the integral value of the loss coefficient in the range of -30°C to -15°C ('), and the transfer resistance performance has the highest correlation with the logarithm of the integral value of the loss coefficient in the range of -30°C to -15°C ('), and the transfer resistance performance is 50 to 6
We have discovered the fact that the correlation is the highest with the logarithm of the integral value of the loss coefficient in the range of 5°C, which was completely unknown until now. ' The present inventor measured rolling resistance and wet grip using this measurement method, and investigated gill and stomer compositions that have better tread performance than the tread conventionally used for -S. As a result, the present invention was completed.

That is, the present invention has a frequency of 1 measured at a heating rate of 1°C/min.
In the temperature dispersion curve of dynamic viscoelasticity at 0 Hz, dynamic strain 0
．． Integral 11W (sv >
': 5 or more, temperature range from 50°C at dynamic strain 1z to 2
．． The present invention relates to a vulcanized elastomer composition characterized in that the vulcanized elastomer has a viscosity of 8 or less, and a tire using the vulcanized elastomer as a tread.

The temperature dispersion of the dynamic viscoelasticity of the vulcanized elastomer that is the basis of the loss coefficient of the present invention is at a frequency of 1QHz and a heating rate of 1°C/
Measurements are made under conditions of 0.5% and 1% dynamic strain.

Based on the obtained temperature dispersion curve at 0.5% dynamic strain,
Integral value of loss coefficient (Sw) and dynamic strain in temperature range -30°C to -15°C1. Based on the temperature dispersion curve in Oz, the integral value of the loss coefficient (, Si<) for the temperature range of 50°C to 65°C is determined. 'SW is 5 or more, SR is 2.
In the case of a vulcanized elastomer having a molecular weight of 8 or less, a tire with low energy loss during running and high running safety can be obtained.

Integration of loss factor in 4 from -30 to -15°C 1 straight 54
When V is 5 or more, wet grip performance superior to that of conventionally used tires can be obtained, and in particular, when V is 6.5 or more, even better wet grip performance can be achieved.

On the other hand, the integral of the loss coefficient at 50 to 65°C is
R has the highest correlation with transfer resistance, but its correlation is lower than the relationship between wet grip and SW.

This is because the transfer resistance is due to energy loss due to compression, bending, and shear motion, and therefore loss compliance (,'E'/(E*)2) and loss modulus (E''
′), the loss coefficient (t'anδ−E・
In the case of radial tires, it has been found that there is a higher correlation with 7 ut ). However, even in this case, if tan δ is decreased, sin δ is decreased, indicating that a tire with low rolling resistance can be provided.

In any case, the SR of the vulcanized elastomer of the tread is 2.
．． If it is set to 8 or less, tires with low transfer resistance can be obtained. Note that it is particularly preferable that SR<2.0.

Vulcanized elastomer (Note 2) exhibiting the above temperature dispersion curve
Multi-molecule distribution.

(Note 3), 5BR-1500 manufactured by Sumitomo Chemical Co., Ltd. (
Note 4) IR-2200 manufactured by Japan Synthetic Rubber Co., Ltd. Example 1 is high vinyl butadiene rubber, 2 is styrene butadiene rubber, 3 is 3,4-isoprene rubber, and 4 is isoprene butadiene rubber thread rubber. It is a polymer prepared by solution polymerization.

The above elastomer compound was cured at 175°C for 2 vulcanization times.
Vulcanization was carried out under conditions of 0 effort, and the integral value of loss coefficient, viscoelastic properties, transfer resistance index and wet grip index were measured under the following conditions. Table of results - (a) Loss coefficient: Integral direct: A sample piece of the vulcanized elastomer with a width of 4 mm x length of 3 mm x thickness of 21 mm was applied to a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho) at a frequency of 10 H and an increase of The loss factor was measured in the temperature range from -50°C to 85°C at a temperature rate of 1°C/min. However, in the range of -50 to -5℃, the dynamic strain is 0.5%, -
Measurements were made at a dynamic strain of 1% in the range of 5 to 85°C. Figures 1 and 2 show the temperature dispersion curves of loss coefficients for each composition obtained. Figure 1 shows a dynamic strain of 0.5%, and Figure 2 shows a dynamic strain of 1%.
The results are shown below. In the figure, (1) to (4) represent each example 1 to
4, (5) 2 and (6) indicate Comparative Examples 1 and 2, respectively.

The integral value of each loss barrier number was determined from the obtained graph.

←) Prepare a sample piece with the same size as the transfer resistance index (a), and measure the above viscoelasticity with an initial strain of 10% and a frequency of I using a speggtrometer.
The loss modulus of each sample was determined at QHz and dynamic strain of 2%.

e9 Wet Grip Index Using a portable skid resistance tester, the frictional resistance on a wet road surface was measured, and Comparative Example 1

[Brief explanation of the drawing]

Figure 1 shows the temperature dispersion curve of the loss coefficient at a dynamic strain of 0.5% for the vulcanized nidistomer compositions of Examples 1 to 4 and Comparative Examples 1 and 2, and Figure 2 shows the temperature dispersion curve of the loss coefficient at a dynamic strain of 1%. The dispersion curve is shown. In the figure, (1) to (4) represent Examples 1 to 4 and (5), respectively.
and (6) show the temperature dispersion curves of Comparative Examples 1 and 2, respectively. Patent Applicant: Sumitomo Gomue Chestnut Co., Ltd. - Acting Patent Attorney Kenzan Bo et al. 14 ”, , , , , ,”11-
−Thursday

Claims (1)

[Claims] 1. In the temperature dispersion curve of dynamic viscoelasticity at a frequency of IQHz measured at a heating rate of 1°C/min, the temperature range from -30°C to -1 at a dynamic strain of 0.5X. Integral value of loss coefficient 11 [(SR ) is 2.8 or less. 2. The vulcanized elastomer composition according to item 1, which has a SW of 6.5 or more. 3. The vulcanized elastomer composition according to item 11 or item 2, which has an SR of 2.0 or less. 4. 1 wave number measured at a heating rate of 1°C/min. QIH
In the temperature dispersion curve of dynamic viscoelasticity at z, dynamic strain 0.5
%, the integral value (SW) of the loss coefficient (tan δ (T)) in the temperature range from -30°C to -15°C is 5 or more,
A tire whose tread is made of a vulcanized elastomer having an integral loss coefficient (SR) of 2.8 or less in a temperature range of 50°C to 65°C at a dynamic strain of 1%. 5. The tire according to item 4, wherein 5.5W is 6.5 or more. 6. The tire according to item 4 or item 5, which has an SR of 2.0 or less.