JPH06263926A - Filler for rubber - Google Patents

Abstract

PURPOSE:To obtain a filler for rubber, composed of surface-treated carbonated calcium silicate hydrate, capable of improving vulcanization properties such as vulcanizing speed in processing while improving mechanical properties such as strength of rubber after addition of the filler and remarkably excellent in workability. CONSTITUTION:This filler for rubber is, prepared by applying a surface treatment and a carbonation treatment to calcium silicate hydrate and has <=5mum, preferably 1 to 3mum average particle diameter. As the calcium silicate hydrate, a light-weight cellular concrete called ALC and widely used as a building material is preferably used. The carbonation degree of calcium silicate hydrate is preferably 100%. Further, as the surface treatment agent, a fatty acid, a resin acid, etc., is recommendably used and the amount of a treatment agent is preferably 0.1 to 0.8mol% based on Ca contained in the whole calcium silicate hydrate in the case of stearic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to rubber fillers.

[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, an object of the present invention is to improve mechanical properties such as strength of rubber itself after adding a filler, and at the same time improve vulcanization characteristics such as vulcanization speed during processing.
Further, it is to provide a rubber filler which is very excellent in terms of workability by maintaining a sufficient scorch time.

[0005]

The present invention has an average particle size of 5 μm.
A rubber filler composed of a surface-treated and 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 porous calcium silicates may not be completely pure, and may contain CSH gel, unreacted siliceous raw material, and the like. In particular,
It has also been found that the strength improving effect is great when unreacted silica is present.

As a method for obtaining calcium silicate hydrate, for example, a method in which a siliceous raw material and a calcareous raw material are mainly used and these are hydrothermally synthesized in an autoclave can be mentioned. 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, AL
C. It is also possible to use defective products generated in the manufacturing process or scraps generated in the current state of construction of buildings, houses, etc., which have been conventionally discarded.

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. When the average particle size is more than 5 μm, the dispersion during filling becomes poor. It may cause a decrease in strength. In addition, it is preferable that a material having a particle diameter of 10 μm or more does not substantially exist. Further, if the calcium silicate hydrate has the above-mentioned average particle size, the shape of the powder need not be particularly limited.

A liquid phase method, a gas phase method and the like can be considered as a method for carbonating calcium silicate hydrate, but the method is not particularly limited. The rate of carbonation (carbonation degree:
The proportion of calcium hydrate in the calcium silicate hydrate is calcium carbonate), but the greater the proportion of carbonation, the longer the scorch time and the significant improvement.
It is sufficient for the scorch time to be 4 to 5 minutes at 150 ° C., which is achieved by using calcium silicate hydrate having a carbonation degree of 40% or more as a rubber filler. Further, the one having a carbonation degree of 100% is more preferable. Further, when calcium silicate hydrate having a carbonation degree of 40% or less is used as a filler, it also has 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%. ), Refers to 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.

As the surface treatment agent of the present invention, those generally used for surface treatment of calcium may be used, and for example, fatty acids, resin acids, lignin and the like may be used. Regarding the amount of the surface treatment agent added, for example, in the case of stearic acid which is a fatty acid, it is 1.5 with respect to the calcium content of the entire calcium silicate hydrate used.
Mol% or less is preferable in that surface treatment can be performed without lowering the strength, and more preferably 0.1 mol% to
0.8 mol% is the most suitable range. The surface treatment may be performed by a known method.

Next, the order of carbonation, pulverization and surface treatment is not particularly limited regardless of the order of treatment, regardless of the physical properties of the rubber filler.

[0012]

[Function] Calcium silicate hydrate has silica and calcium as main chemical components. Mechanical properties after filling are maintained or improved by the inclusion of silica, and the carbonated calcium makes the pH of the filler closer to neutral than that of calcium itself, so that sufficient scorch time during processing is ensured. It has the effect of promoting vulcanization while maintaining it.

Further, when the average particle diameter is 5 μm or less, the dispersibility is improved, and by performing the surface treatment, mechanical properties such as tensile strength of the rubber after the addition of the filler can be improved.

[0014]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. As the calcium silicate hydrate used in the examples, ALC was used. Carbonation of the above ALC is
Leave the ALC in a 100% carbon dioxide atmosphere for an appropriate time,
Carbonation treatment was carried out by leaving until the respective carbonation degrees were reached. The carbonated ALC was then ground to the appropriate particle size. The surface treatment of carbonated ALC is carried out by dissolving stearic acid of a predetermined concentration in ethanol according to the concentration of addition, adding the solution to carbonated ALC, appropriately stirring and then drying with a spray dryer to obtain a rubber filler. It was used as a sample.

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

[0016]

[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

[0018]

Example 1 ALC is 100% carbonated to have an average particle size of 2
What was pulverized to have a particle size of 10 μm (there was essentially no particle having a particle size of 10 μm or more) and stearic acid was added in an amount of 0.5 mol% with respect to the calcium content in the ALC was used as a rubber filler. The rubber was processed according to the compounding ratio. The mechanical properties of the processed rubber such as vulcanization speed, scorch time and rubber strength were measured. The results are shown in Table 2. The workability and workability during processing were good.

[0019]

[Example 2] ALC was carbonized to 50% and the average particle size was 2μ.
to a rubber filler in which 0.8 mol% of stearic acid was added to the calcium content of the ALC used, was added to the above composition. The rubber was processed according to the ratio. 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 1] ALC is 100% carbonated to have an average particle size of 1
A rubber filler was prepared by adding 1.0 mol% of stearic acid to the calcium content of the used ALC to a powder pulverized to 0 μm, and the rubber was processed according to the above compounding ratio. The same measurement as in Example 1 was performed on the processed rubber. The results are shown in Table 1. The workability and workability during processing were good.

[0021]

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

[0022]

Comparative Example 3 Clays having an average particle size of 2 μm were used as a rubber filler, and rubber was processed according to the above compounding ratio. The same measurement as in Example 1 was performed on the processed rubber. The results are shown in Table 1. Regarding workability and workability during processing,
It was good. As for clay, shiraishi calcium-based hard clay was used.

[0023]

[Table 2]

[0024]

EFFECT OF THE INVENTION The rubber filler according to the present invention has mechanical properties after addition of the filler by surface-treating the carbonated calcium silicate hydrate and pulverizing the average particle size to a carbonation degree of 5 μm or less. The epoch-making rubber filler that improves the vulcanization characteristics by improving the vulcanization speed during processing, and at the same time maintains the sufficient scorch time to improve the processability and handleability. To do.

Claims (1)

[Claims] 1. A rubber filler composed of surface-treated and carbonated calcium silicate hydrate having an average particle size of 5 μm or less.