JPH06256581A - Filler for rubber - Google Patents

Abstract

PURPOSE:To obtain the subject filler consisting of a carbonated calcium silicate hydrate having a specified average particle diameter, capable of improving vulcanization characteristics such as vulcanizing rate in molding while improving dynamic physical properties such as strength of rubber itself and excellent also in moldability. CONSTITUTION:This filler consists of carbonated calcium silicate hydrate having <=5mum, preferably 1-3mum average particle diameter. As the carbonated calcium silicate, a substance obtained by using light-weight cellular concrete called as ALC as calcium silicate and simultaneously carbonating the concrete in 100% carbonatation degree is preferably used. The carbonatation is e.g. carried out by allowing the ALC powder to stand in 100% CO2 gas atmosphere.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a filler for rubber.

[0002]

2. Description of the Related Art Up to now, inorganic compounds such as calcium carbonate and clay have been mainly used as rubber fillers.

[0003]

However, when calcium carbonate is used as a rubber filler, the rubber itself has a poor strength development, and when clay is used, it is slightly acidic and thus vulcanizes slightly. Tend. Although activators such as glycol and amine are added to improve the above-mentioned drawbacks, there is still room for improvement in vulcanization characteristics.

In view of the above points, the present invention improves the mechanical properties such as the strength of the rubber itself after the addition of the filler and at the same time improves the vulcanization characteristics such as the vulcanization rate during processing, and A rubber filler that is very excellent in terms of workability is provided by maintaining a sufficient scorch time.

[0005]

The present invention has an average particle size of 5 μm.
It is a filler for rubber which is a carbonated calcium silicate hydrate of m or less. Examples of the calcium silicate hydrate used as the raw material of the present invention include xonotlite, tobermorite, gyrolite, foshajeite, hirebrandite. These calcium silicate hydrates need not be used alone, but can be used as a mixture of two or more kinds. Further, these calcium silicate hydrates may not be completely pure, and may include CSH gel, unreacted siliceous raw material, and the like. In particular, it has been found that the strength improving effect is great when unreacted silica is present.

As a method for obtaining calcium silicate hydrate, for example, there is a method in which a siliceous raw material and a calcareous raw material are mainly used and these are hydrothermally synthesized in an autoclave. Further, among calcium silicate hydrates, a lightweight cellular concrete, that is, a material called ALC, which is widely used as a building material, is easily available, and is also preferable as the composition of the present invention. It is not necessary to use a new product,
It is also possible to use a defective product generated in the LC manufacturing process or a scrap that has been conventionally discarded such as a scrap material generated in the current state of construction of a building or a house.

The average particle size of this calcium silicate hydrate is
There is no particular limitation as long as it is 5 μm or less, but it is preferable to use calcium silicate hydrate having an average particle size of 1 to 3 μm. The average particle size as used herein means one calculated from the particle size distribution measured by a laser diffraction type particle size distribution measuring device. If the average particle size is more than 5 μm, the dispersion during filling becomes poor, which causes a decrease in strength and the like.

It is preferable that there is substantially no particles having a particle size of 10 μm or more. Further, the shape is not particularly limited as long as it is a calcium silicate hydrate having the above average particle diameter. The method of carbonating calcium silicate of the present invention may be a liquid phase method, a vapor phase method, or the like, but the method is not particularly limited. In addition, it is the rate of carbonation (carbonation degree: the rate at which the calcium content of calcium silicate hydrate turns into calcium carbonate). The greater the rate of carbonation, the longer the scorch time and the significant improvement. However, since it is sufficient for the scorch time to be 4 to 5 minutes at 150 ° C., it is achieved by using calcium silicate hydrate having a carbonation degree of 40% or more as a rubber filler. More preferably, the carbonation degree is 100%. The degree of carbonation is 4
Even when 0% or less of calcium silicate hydrate is used as a filler, there is an effect of extending the scorch time.

The term "carbonation degree" as used herein refers to the ratio of calcium content to calcium carbonate (when the total calcium content of the hydrate is calcium carbonate, the carbonation content is 1).
00%), and the proportion of calcium silicate hydrate used as a whole. The carbonation degree can be measured from the amount of carbon dioxide gas generated by reacting a sample with hydrochloric acid.

Next, regarding the order of carbonation and crushing, whichever is treated first is not particularly concerned regardless of the physical properties of the rubber filler.

[0011]

[Function] Calcium silicate hydrate has silica and calcium as main chemical components. By including silica, the mechanical properties after filling are maintained or improved, and the carbonated calcium content is the pH of the filler.
Since it is around 9.5, there is an effect of promoting vulcanization while maintaining a sufficient scorch time during processing.

Further, by pulverizing the average particle diameter to a carbonation degree of 5 μm or less, mechanical properties such as tensile strength after addition of the filler can be improved.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. The calcium silicate hydrate used in the examples was prepared by crushing ALC into an appropriate particle size and then leaving the ALC powder thus obtained in an atmosphere of 100% carbon dioxide for an appropriate time until the carbonation degree was adjusted to the respective values. Carbonation was performed by leaving it to stand. What was dried with a spray dryer was used.

Table 1 shows the compounding ratio in rubber processing in the examples.

[0015]

[Table 1]

The particle size distribution, vulcanization rate, and rubber strength shown in Examples and Comparative Examples were measured by the following methods. Particle size distribution measurement: Measured by a laser diffraction type particle size distribution measuring device Vulcanization property measurement: measured by rheometer Mechanical physical property measurement: measured according to JIS-K6301

[0017]

Example 1 ALC is 100% carbonated to have an average particle size of 2
The pulverized product having a particle size of 10 μm (the product having a particle size of 10 μm was not substantially present) was used as a rubber filler, and the rubber was processed according to the compounding ratio shown in Table 1. With respect to the processed rubber, vulcanization characteristics such as vulcanization speed and scorch time, and mechanical properties of the rubber such as rubber strength were measured. The results are shown in Table 2. Also,
The workability and workability during processing were good.

[0018]

[Example 2] ALC was carbonized to 50% and the average particle size was 2μ.
The rubber was processed according to the compounding ratio shown in Table 1 by using the material pulverized into m (10 μm was substantially absent) as a rubber filler. The same measurement as in Example 1 was performed on the processed rubber. The results are shown in Table 2. The workability and workability during processing were good.

[0019]

[Comparative Example 1] ALC is 100% carbonated to have an average particle size of 1
Rubber was processed in accordance with the compounding ratio shown in Table 1 by using the material crushed to 0 μm as a filler. The same measurement as in Example 1 was performed on the processed rubber. The results are shown in Table 2. The workability and workability during processing were good.

[0020]

Comparative Example 2 Calcium carbonate having an average particle size of 3 μm was used as a rubber filler, and the rubber was processed according to the compounding ratio shown in Table 1. The same measurement as in Example 1 was performed on the processed rubber. The results are shown in Table 2. The workability and workability during processing were good.

[0021]

Comparative Example 3 The same measurement as in Example 1 was carried out by processing a rubber according to the above compounding ratio using a shiraishi calcium-based hard clay having an average particle size of 2 μm as a rubber filler. The results are shown in Table 2. The workability and workability during processing were good.

[0022]

[Table 2]

[0023]

EFFECTS OF THE INVENTION The present invention provides an epoch-making rubber filler which has improved processability and handleability while maintaining the strength of the rubber after filling by the above constitution. You can

Claims (1)

[Claims] 1. A filler for rubber which is a carbonated calcium silicate hydrate having an average particle size of 5 μm or less.