JPH0971486A - Production of calcium silicate compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a calcium silicate compact, having features of a light weight, high strength, low water absorptivity, heat resistance, fire proofing properties, etc., and suitable as a building material excellent in even workability at a cost lower than before. SOLUTION: This method for producing a calcium silicate compact is to use a fibrous resin as a resin and keep the formed compact at a temperature above the melting temperature of the fibrous resin in the method for producing the calcium silicate compact comprising mixing calcium silicate hydrate with the resin and water, providing a slurry, then dehydrating and forming the slurry and carrying out the drying and removal of water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a calcium silicate compact. More specifically, a calcium silicate compact suitable for a building material, which has characteristics such as light weight, high strength, low water absorption, heat resistance, and fire resistance, and is excellent in workability such as sawing and nailing. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, calcium silicate hydrate, a water-dispersible resin ( For example, a styrene-butadiene copolymer latex containing a carboxyl group), a cationic polymer flocculant,
A synthetic wood is proposed in which an aqueous slurry obtained by mixing reinforcing fibers and water is dehydrated by a method such as pressure filtration, molded, and dried (JP-B-62-32148).

However, the molded product obtained by this technique has a bulk density of 0.5 g / cm ³ and a bending strength of about 100 kg / cm ^2, which is very low in mechanical strength as compared with natural wood. For example, it is used as a structural member for construction. It was difficult to use.
In addition, since it has extremely high water absorption, it has problems such as poor frost resistance and easy surface contamination, so it can be used outdoors or around water without extensive surface treatment such as painting. It was also difficult to do.

Therefore, as a method for improving the problems of this molded article, (1) a method of adding a coupling agent to a molded article composed of calcium silicate hydrate-resin-reinforcing fiber (Japanese Patent Publication No. 5-17187). JP-A-63-1000
49), (2) a method of adding a dispersant for cement (JP-A-62-123053), (3) a method of adding a substance which reacts with water to form ettringite (JP-A-3-3635). Gazette), (4) Method of adding sulfate of alkali metal or magnesium (JP-A-6-488)
No. 07), (5) a method of using a thermosetting water-soluble cationic resin and a polymer latex in combination with the resin (JP-A-1-119554), and (6) a resin containing a specific synthetic resin latex or emulsion. Method used (Japanese Patent Publication No. 4-72788, Japanese Patent Application Laid-Open No. 64-72950), (7) Method of adding water repellent (Japanese Patent Application Laid-Open No. 1-264)
948), (8) a method of using a powdered resin as the resin (Japanese Patent Application Laid-Open No. 4-6137), and the like.

[0005]

However, although the molded articles produced by the methods described in the above (1) to (6) are found to have improved mechanical strength, their water absorption is still at a high level. In addition, the molded product according to the method described in (7) has low water absorption, but has little improvement in mechanical strength, and uses an expensive water repellent such as polydimethylsilyloxane. Therefore, the production cost of the molded body is significantly increased, and it is not practical.

Further, in all of these methods, since the resin is added as a latex or emulsion, the dehydration property of the slurry may be deteriorated at the time of molding, or the resin may escape with water during the dehydration. , That measure is needed. In addition, since latex and emulsion type resins usually contain a considerable amount of surfactants, special treatment may be required to drain the water generated by dehydration during molding, which increases manufacturing costs. Cause

The method described in (8) has been proposed as a method for solving the problems caused by the addition of such latex or emulsion type resin, and described in (8). According to the method, the processability of the molded product and the dust generation property during the process are also improved. However, in the method described in (8), the strength of the molded body is improved and the water absorption is reduced.
There is no description.

The object of the present invention is a method of producing a calcium silicate compact having high strength, low water absorption, light weight, heat resistance, fire resistance, etc. and excellent workability at a lower cost. To provide.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in view of the above-mentioned circumstances, and as a result, the resin was made into a fibrous form and added to the slurry, and after the slurry was formed, the resin By heating and maintaining the temperature above the melting temperature to melt and flow the resin, in addition to being able to solve the above-mentioned problems that occur due to the addition of a latex or emulsion type resin, high strength and low water absorption It has been found that a calcium silicate compact can be obtained, and the present invention has been completed.

That is, the present invention relates to a method for producing a calcium silicate compact by dehydrating and molding a slurry obtained by mixing calcium silicate hydrate, a resin and water, and drying the slurry.
A method for producing a calcium silicate compact, which comprises using a fibrous resin as the resin and, after molding, holding the fibrous resin at a temperature higher than the melting temperature of the fibrous resin. Hereinafter, the present invention will be described in detail.

The calcium silicate hydrate according to the present invention is
After calcining raw materials such as quick lime and slaked lime and siliceous raw materials such as silica stone powder are dispersed in water to form an aqueous slurry,
A substance obtained by a hydrothermal reaction is a crystalline substance such as tobermorite or xonotlite, or CSH-I or CSH-I.
One having a relatively low crystallinity called I can be exemplified. The blending ratio of the calcareous raw material and the siliceous raw material varies depending on the type of calcium silicate hydrate to be synthesized and is not particularly limited, but in the case of tobermorite, CaO / SiO ₂
The molar ratio is preferably about 0.8, and in the case of xonotlite, it is preferably about 1.

The calcium silicate hydrate is obtained as an aqueous slurry, but in the present invention, this slurry may be used as it is without being dried, or the slurry may be dried and made into powder. The production method of the present invention is characterized in that a fibrous resin is used as the resin, but the resin may be either a thermoplastic resin or a thermosetting resin.

Examples of the thermoplastic resin include polyamide, polyester, polyvinyl alcohol, polyethylene, polypropylene, aramid, and acryl, but are not limited thereto. Examples of the thermosetting resin include epoxy, phenol, melamine, etc., but are not limited to these.

The resins may be used alone or in combination of two or more. The fibrous resin used in the present invention has a diameter of 5
It is preferable to use one having a length of 0 μm or less and a length of 1 to 50 mm, and a diameter of 20 μm or less and a length of 3 to 20 m.
More preferably, it is in the range of m. If the diameter is too large or the length is too short, it becomes difficult to obtain a high-strength molded product. On the other hand, if the length is too long, it is difficult to uniformly disperse it in the slurry, which causes deterioration of various physical properties of the molded product.

The amount of the fibrous resin used in the present invention is not particularly limited, and may be appropriately selected depending on the physical properties of the molded product to be produced, but with respect to 100 parts by weight of calcium silicate hydrate. It is preferably 3 to 30 parts by weight. If the amount of addition is small, it is difficult to increase the strength and water absorption of the calcium silicate compact, and if it is too large, the heat resistance and fire resistance deteriorate.

In the production method of the present invention, a powdered resin may be added as the resin in addition to the fibrous resin. Also,
Among the effects of the present invention, if it is desired to achieve only high strength of the calcium silicate compact, or only high strength and low water absorption, use a water-soluble resin or an emulsion type resin in combination with the fibrous resin. Is also possible. In the production method of the present invention, reinforcing fibers may be added if necessary. Addition of reinforcing fibers is effective in increasing strength.

The reinforcing fibers used in the present invention are glass fibers,
Carbon fiber, rock wool, pulp, rayon, etc. may be used alone or in combination of two or more kinds. When using organic fibers, the total amount of resin and organic fibers is preferably 30 parts by weight or less with respect to 100 parts by weight of calcium silicate hydrate. When it exceeds 30 parts by weight, the heat resistance and fire resistance are deteriorated.

In the production method of the present invention, it is also possible to replace a part of the calcium silicate hydrate with an inorganic substance generally known as a filler such as wollastonite, sepiolite, talc and aluminum hydroxide. However, the substitution rate is preferably 20% or less. If it exceeds 20%, the strength of the calcium silicate compact tends to decrease.
In the production method of the present invention, first, a calcium silicate hydrate, a fibrous resin, water, and reinforcing fibers added as necessary are mixed to form a uniform aqueous slurry. The order of feeding the raw materials and the mixing method are not particularly limited as long as the raw materials are uniformly mixed, and may be determined according to the situation. In the slurry, a dispersant for promoting uniform mixing of each raw material, a coagulant for improving drainage and dehydration of the slurry at the time of molding, a molding aid for improving moldability and shape retention. You may add agents etc. as needed.

The slurry thus obtained is dehydrated by a method such as pressure filtration and pressure-molded to obtain a molded body. As a molding method, a conventionally known method such as a press molding method, a papermaking molding method and an extrusion molding method can be appropriately adopted depending on the purpose and application. The manufacturing method of the present invention is characterized in that after the slurry is dehydrated and molded, the slurry is dried to remove water, and in addition, the slurry is heated to or above the melting temperature of the fibrous resin and held. Examples of the method of heating and holding include a method using an electric dryer and a method using electromagnetic wave irradiation.

By melting and flowing the fibrous resin, it becomes possible to increase the strength of the calcium silicate compact. The time for which the fibrous resin is held at the melting temperature or higher is preferably determined by conditions such as temperature, shape of the molded product, and type of resin. Further, first, a molded body in a state of containing no moisture after drying is obtained, and then the molded body is heated and held at a temperature not lower than the melting temperature of the fibrous resin to melt and flow the fibrous resin in a state of containing no moisture. If this is the case, in addition to higher strength, lower water absorption becomes possible.

In this case, the drying for removing water is
It may be performed under the condition that the fibrous resin is melted or not melted, and examples thereof include methods such as heat drying, drying by electromagnetic wave irradiation, and vacuum drying. The number of times that the fibrous resin is heated and held at a temperature equal to or higher than the melting temperature to melt and flow the resin depends on the composition of the slurry and the desired physical properties.
It may be more than once.

The melting temperature of the resin referred to in the present invention is defined by JIS
Melting point measured according to K 6910. When the melting temperature is measured with a range, it means the upper limit temperature. For thermosetting resins, the melting point measured for the resin at the stage where the crosslinking reaction has not proceeded.
In addition, the term “drying completed” in the present invention means a state in which no weight loss is observed due to the treatment for drying. For example, when a fibrous polypropylene resin is used, it is dried by heating at 190 ° C. for 5 hours, The state where the decrease is no longer seen.

The method for producing a calcium silicate compact according to the present invention can enhance the strength of the obtained calcium silicate compact, but it is considered to be achieved by the following mechanism. First, when a latex or emulsion type resin is added, the resin also enters inside the calcium silicate hydrate particles, so the amount of resin that effectively acts on the adhesion between calcium silicate hydrate particles is actually Less than the amount added. On the other hand, when a fibrous solid resin is added, the viscosity of the resin does not decrease to such a level that it can easily enter the inside of the calcium silicate hydrate particles even if it is melted. The amount of resin that effectively acts on adhesion increases.

Further, even if the same solid resin is used, in the case of powdery resin, it is interposed between the calcium silicate hydrate particles and contributes to the reinforcement between the hydrate particles that are originally adjacent to each other. In the case of a resin, since it intervenes so as to straddle the particles and also bridges the hydrate particles that are not adjacent to each other in a bridging manner, a more effective reinforcing effect can be exhibited. Next, a slurry is formed, dehydrated, molded, and then dried in a state of a calcium silicate compact from which water is removed, and further heated to a temperature above the melting temperature of the fibrous resin and held to melt the resin. By the treatment, not only the strength of the calcium silicate compact can be further increased, but also the water absorption can be reduced.

Conventionally, a calcium silicate compact having a low water absorption has been obtained by adding an expensive additive such as a water repellent. However, according to the present invention, the low water absorbency is not added. A water-absorbing calcium silicate compact is obtained. According to an electron microscope observation (SEM observation), the molded body according to the prior art (for example, the molded body according to Japanese Patent Publication No. 62-32148) is three-dimensional though the resin is present between the particles of the calcium silicate hydrate. The continuity is poor, and therefore it is considered that it exhibits high water absorption in addition to insufficient strength.

However, after the slurry is formed and dried, the fibrous resin is melted by being heated and maintained at a temperature not lower than the melting temperature of the fibrous resin, and the resin is made to flow. Is considered to be formed, the strength of the calcium silicate compact is further improved, and the water absorbency becomes low. The condition for drying the calcium silicate compact may be a condition in which the fibrous resin melts or a condition in which the fibrous resin does not melt. It is preferable to heat and maintain the temperature above the melting temperature in order to obtain a calcium silicate compact having low water absorption. After drying and removing water, by heating and holding above the melting temperature of the resin, the structural changes that occur in the resin layer during water evaporation become continuous in the three-dimensional direction, resulting in low water absorption. It is considered that a calcium silicate compact can be obtained.

When a thermosetting resin is used, the resin is heated and held at a temperature not lower than the melting temperature of the resin and then further heated to accelerate the crosslinking reaction of the resin to cure the resin. In the present invention, it is desirable that the series of heat treatments after molding be performed under conditions that do not deteriorate the resin.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to Examples. The physical properties and the like in the examples were measured by the methods described below. (1) Bending strength It was measured according to JIS A 1408.

(2) Water absorption amount A test piece of 200 × 200 × 20 mm was allowed to stand in a room at a temperature of 20 ° C. and a relative humidity of 60% until the water content reached equilibrium, and then weighed to obtain a dry weight M _d (g ). Next, this test body is placed on a surface of 200 × 200 mm in a horizontal position of 20
Place in water at -25 ° C so that the upper surface is about 30 mm below the surface of the water, and leave it for 24 hours. After 24 hours,
The test body is taken out, water adhering to the surface is wiped off with a compress, and the weight is immediately measured, and this is taken as the weight M _w (g) when absorbing water. The water absorption amount was calculated by the following formula.

Water absorption amount (g / cm ³ ) = (M _w −M _d ) / V V: test body volume (cm ³ ) calculated from the outer size measurement result performed on the test body during dry weight measurement

[0031]

Example 1 Silica stone powder and slaked lime were mixed so that a CaO / SiO ₂ molar ratio was 1, water was added in an amount 10 times the total weight of silica stone powder and slaked lime, and the mixture was stirred in an autoclave. While performing hydrothermal reaction at a temperature of 210 ° C. and a pressure of 19 kg / cm ² for 6 hours, a calcium silicate hydrate slurry was obtained.

Calcium silicate hydrate 10 was added to this slurry.
Fibrous polypropylene resin (diameter: 12
μm, length: 5 mm, melting temperature: 174 ° C.), 15 parts by weight, and 3 parts by weight of glass fiber were added and mixed so as to be uniform. This slurry is poured into a mold of 300 × 300 mm, dehydrated under pressure to be molded, and dried by heating at 190 ° C. for 5 hours until moisture disappears and weight reduction is not obtained to obtain a calcium silicate compact. It was The test results of the calcium silicate compact are shown in Table 1.

[0033]

Example 2 The same calcium silicate hydrate slurry as in Example 1 was added to 100 parts by weight of calcium silicate hydrate and a fibrous polyester resin (fiber diameter: 10 μm, fiber length 10).
mm, melting temperature: 260 ° C.) 10 parts by weight, glass fiber 6
Parts by weight were added and mixed to be uniform.

This slurry was poured into a mold of 300 × 300 mm, subjected to pressure dehydration molding, and then heat-dried at 270 ° C. for 4 hours until no weight reduction was observed to obtain a calcium silicate compact. The test results of the calcium silicate compact are shown in Table 1.

[0035]

Example 3 The same slurry as in Example 1 was used at 300 × 30.
It is poured into a 0 mm form, dehydrated under pressure, molded, and
After heating and drying at 0 ° C. for 8 hours and confirming that no weight loss due to heating was observed, heating at 190 ° C. for 3 hours gave a calcium silicate compact. The test results of the calcium silicate compact are shown in Table 1.

[0036]

Example 4 The same slurry as in Example 2 was added to 300 × 30.
Pour into a 0 mm form, dewatering under pressure, molding, 15
After heating and drying at 0 ° C for 7 hours and confirming that weight loss due to heating is not seen, heating at 270 ° C for 2 hours,
A calcium silicate compact was obtained. The test results of the calcium silicate compact are shown in Table 1.

[0037]

Example 5 A calcium silicate hydrate slurry similar to that of Example 1 was added to 100 parts by weight of calcium silicate hydrate to form a fibrous polyethylene resin (fiber diameter: 20 μm, fiber length: 1).
0 mm, melting temperature: 166 ° C.) 20 parts by weight, glass fibers 3 parts by weight were added and mixed so as to be uniform.

This slurry was poured into a 300 × 300 mm mold, dehydrated under pressure, molded, and dried by heating at 120 ° C. for 10 hours. After confirming that no weight loss due to heating was observed, 180 ° C. By heating for 2 hours, a calcium silicate compact was obtained. The test results of the calcium silicate compact are shown in Table 1.

[0039]

[Comparative Example 1] Acrylic ester copolymer emulsion (melting temperature during film formation: 139 ° C) was added to 100 parts by weight of calcium silicate hydrate in the same calcium silicate hydrate slurry as in Example 1. Parts by weight (in terms of solid content) and 3 parts by weight of glass fiber were added and mixed to be uniform.

This slurry was poured into a mold of 300 × 300 mm, subjected to pressure dehydration molding, and heated and dried at 120 ° C. for 10 hours to obtain a calcium silicate compact. The test results of the molded product are shown in Table 1.

[0041]

Comparative Example 2 Polypropylene resin powder (average particle size:
A calcium silicate compact was obtained in the same manner as in Example 1 except that the thickness was 60 μm). Table 1 shows the test results of the molded products.
It was shown to.

[0042]

Comparative Example 3 A calcium silicate compact was obtained in the same manner as in Example 1 except that only heating at 130 ° C. for 12 hours was performed after pressure dehydration. The test results of the molded product are shown in Table 1.

[0043]

[Table 1]

[0044]

The method for producing a calcium silicate compact of the present invention can produce a calcium silicate compact having high strength and low water absorption in addition to the characteristics of the conventional calcium silicate-based synthetic wood. . That is, light weight, heat resistance,
A calcium silicate compact, which has characteristics such as fire resistance and is extremely high in strength as compared with conventional ones, has low water absorption, and is excellent in workability as a building material, is manufactured at a lower cost. It is possible.

Claims (1)

[Claims] 1. A method for producing a calcium silicate compact by dehydrating and molding a slurry obtained by mixing calcium silicate hydrate, a resin and water, and using a fibrous resin as the resin, and after molding the fiber. A method for producing a calcium silicate compact, which comprises heating and holding the resin at a temperature equal to or higher than the melting temperature of the resin.