JPH0216256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fibrous hillebrandite-hoshyayite, which is a symbiotic product of crystalline hillebrandite and crystalline hoshyayite with a crystal length of 50 μm or more, and a method for producing the same.

Conventionally, asbestos has been a typical inorganic fiber, and it has long fiber length and is of high industrial significance, but as it is naturally occurring, it is predicted that it will be depleted in the future, and in recent years It has come to be regarded as a carcinogenic substance and is considered an undesirable material from the standpoint of environmental conservation. Glass fiber and rock wool, which are commonly known inorganic fibers other than asbestos, are used as heat insulating materials, but because they have poor alkali resistance, they are not necessarily versatile as fillers and reinforcing materials. Further, although ceramic fibers have various excellent properties, they are too expensive and cannot be put to practical use as general-purpose industrial materials such as reinforcing materials and fillers.

On the other hand, hillebrandite and hosiyayite are substances that can be synthesized relatively easily using silicic acid and calcareous raw materials, and these raw materials are abundant in Japan and can be obtained at low cost, and their characteristics are Since it is a mineral mainly composed of calcium silicate, it has excellent heat insulation properties and has an excellent affinity with water, and several attempts have been made to make fibers from its composites.

For example, although we added alkali and various other additives to the three-component system of CaO, SiO ₂ and H ₂ O, and investigated the temperature, pressure, time, composition, etc., it was not possible to make long fiber materials from hillebrandite and hosiyayite. Nakatsuta.

Hillebrandite and hosiyayite, which can currently be produced industrially, are fine crystals with a crystal length of several micrometers, and have the disadvantage of being prone to agglomeration and having excessive resistance.

The present inventors developed a completely new hydrothermal synthesis technology in which calcium silicate hydrate, mainly containing calcium silicate hydrate, is added to hot alkaline water that has been preset at high temperature and pressure to perform hydrothermal synthesis. As a result, we were able to obtain fibrous fillebrandite/hosiyayite, which is mainly a symbiotic combination of crystalline hillebrandite and crystalline hosiyayite, with most of the crystal lengths being 50 μm or more.

As a result of X-ray diffraction, the product of the present invention was identified as a symbiotic product of hillebrandite and hosiyayite. Also,
As a result of thermal analysis, it has been found that it has better thermal stability than tobermorite, which is one of the typical calcium silicate on the market, so it can be used as a heat insulating material and a heat resistant material, and has good transient properties. Since it is bulky, it was discovered that it could be used as a filler or reinforcing material for synthetic resin molded products, and the present invention was completed.

That is, the first invention of the present invention has a crystal length of 50 μm.
The present invention is a fibrous hillebrandite-hoshyayite characterized by being composed of a symbiotic substance of the above-described crystalline hillebrandite and crystalline hoshyayite.

The second invention is characterized in that calcium silicate hydrate is added to hot alkaline water preset at high temperature and high pressure, and a hydrothermal reaction is caused to produce a symbiosis of fibrous crystalline hillbrandite and crystalline hosiyayite. This is a method for producing fibrous hillbrandite/hosiyayite.

Here, the alkali of the hot alkaline water refers to alkaline substances such as alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, and an alkali concentration of 0.5 to 4 mol/mole is sufficient.

Calcium silicate hydrate is concrete, mortar, slurry, autoclave-cured aerated concrete, etc. obtained by curing silicic acid and calcareous substances at room temperature to high temperature and high pressure with saturated vapor pressure.
It refers to a CaO--SiO ₂ --H ₂ O-based substance, and it is sufficient that the CaO/SiO ₂ molar ratio of calcium silicate hydrate as a starting material is 0.3 to 1.5. The mixing ratio of hot alkaline water and calcium silicate hydrate as a starting material in the hydrothermal reaction system is arbitrary, but preferably about 10 parts by weight of hot alkaline water to 1 part by weight of calcium silicate hydrate. It is sufficient to use at least part by weight.

The hydrothermal reaction referred to in this invention refers to promoting a crystallization reaction under the saturated vapor pressure of hot alkaline water, and a temperature of 150 to 300°C is sufficient for forming fibrous hillebrandite/hosiyaite crystals.

After the completion of the hydrothermal reaction, the solid content of fibrous hillebrandite/hosiyayite crystals is taken out from the reaction tank as a slurry suspended in water and separated, and the dried product is in the form of white powder or flakes. It is a fibrous material that easily permeates water. This fibrous material has extremely excellent heat resistance and alkali resistance, as shown in the examples below. Furthermore, since it is a fibrous material with a crystal length of 50 μm or more, it can be used as a reinforcing filler, a catalyst carrier, a filter material, an adsorbent, etc.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Note that the measurement conditions in the examples are as follows.

(1) Bulk density Measured in accordance with JIS K6220, a test method for rubber compounding agents.

(2) X-ray diffraction Measurement was performed using Cu anticathode, Ni filter, tube voltage 30KV, tube current 15mA, full scale count 1000cps, and scanning speed 20θ degrees/min.

(3) Differential thermal analysis Sample weight 10mg, DTA rangefinder 100μV, heating rate
Measured at 10°C/min.

Example 1 Silver-lined autoclave internal volume 150ml
Pour approximately 1/2 of the internal volume of a 2 mol/aqueous sodium hydroxide solution into the container, seal it, and heat it to 230°C. On the other hand, white carbon (SiO ₂ = 86%) 48 parts by weight, slaked lime (CaO = 74%) 52 parts by weight, CaO / SiO ₂ molar ratio ≒
1. A suspension of amorphous calcium silicate hydrate, prepared by heating a mixture of 1000 parts by weight of water at about 90°C for 5 hours, was poured into the hot alkaline water using a pressure pump to add about 1/of the internal volume of the autoclave. Put 4. The results of X-ray diffraction, differential thermal analysis, and scanning electron microscopy of the product of the present invention, which was held at 230°C for 5 hours to cause a hydrothermal reaction, were cooled, the contents were taken out, washed with water, and dried at 105±5°C. It is shown in FIGS. 1 to 3.

As is clear from FIG. 1, the product of the present invention was identified as a symbiotic species of hillebrandite and hosiyayite.
The thermal behavior of the product of the present invention, as shown in Figure 2, shows endothermic peaks near 600°C and 720°C.
Thermal shrinkage due to dehydration is extremely small compared to tobermorite (usually the loss on heating of tobermorite is approximately 800
It reaches a constant mass at ℃, and its value is about 16%. ), it had excellent properties as a heat-resistant material. On the other hand, the crystal shape of the product of the present invention was fibrous, as is clear from FIG. 3, and most of the crystals had a length of 50 μm or more, with an average length of 100 μm.

It was experimentally confirmed that the product of the present invention has a bulk density of 0.15 and can be used as a filler and overfill material for thermosetting resins and thermoplastic resins.

Example 2 As a result of repeating Example 1 by replacing the 2 mol/aqueous sodium hydroxide solution with a 2 mol/aqueous potassium hydroxide solution, crystalline hillebrandite and crystalline hosiyayite with a crystal length of 50 μm or more and an average length of 100 μm were obtained. symbionts were obtained.

The material properties of the product of the present invention were similar to those of the product obtained in Example 1.

Example 3 Silver-lined autoclave internal volume 1500ml
Pour about 1/2 of the internal volume of a 2 mol/aqueous sodium hydroxide solution into the container, seal it, and heat it to 230°C. Hebel (trademark) powder manufactured by Asahi Kasei Corporation (50 μm or less, CaO/SiO ₂ , molar ratio ≒ 0.6) 100 parts by weight, water
1000 parts by weight of the suspension was poured into the above hot alkali using a pressure pump, about 1/4 of the internal volume of the autoclave.
inject. As a result of a hydrothermal reaction held at 230°C for 7 hours, a symbiotic of crystalline hillebrandite and crystalline hosiyayite with a crystal length of 50 μm or more and an average length of 100 μm was obtained. The material properties of the product of the present invention were similar to those of the product obtained in Example 1.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram of the product of the present invention, FIG. 2 is a differential thermal analysis diagram, and FIG. 3 is a micrograph thereof.

Claims (1)

[Scope of Claims] 1. Fibrous hillebrandite and hosiyayite characterized by being composed of a symbiotic substance of crystalline hillebrandite and crystalline hosiyayite with a crystal length of 50 μm or more. 2. Alkali metal hydroxide preset at high temperature and high pressure. into hot alkaline water with a concentration of 0.5 to 4 mol/mole.
Calcium silicate hydrate with a CaO/SiO ₂ molar ratio of 0.3 to 1.5 is added and subjected to a hydrothermal reaction under saturated vapor pressure at 150 to 300°C to produce a symbiotic of fibrous crystalline hillebrandite and crystalline hosiyayite. A method for producing fibrous fillebrandite/hosiyayite, which is characterized by the following: