JP2002080265A - Method of manufacturing inorganic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method obtaining an inorganic molding with high water resistance, thermal resistance, thermal impact resistance and dimensional stability by heating and curing curable composition containing acidic metal phosphate at a comparably low temperature. SOLUTION: The inorganic molding is obtained by using the acidic metal phosphate which is previously reacted with phosphoric acid and a kind of its curing agent of hydroxide of trivalent metal. At the time of obtaining the aqueous solution or water dispersion liquid of the acid metal phosphate, the ratio of mol number of phosphoric acid ion to mol number of metallic ion number is prescribed within fixed range. Further, at the time of obtaining the curable composition by mixing water solution or water dispersion liquid of the acid metal phosphate with curing agent, the ratio of total valence number of phosphoric ion to total valence number of metallic ion is prescribed within a fixed range. The inorganic molding is molded and cured at a low temperature of 120-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inorganic molded article suitably used, for example, as a building material, an industrial structural material or a member, and more particularly, to a method for producing an inorganic material which has been widely used. The present invention relates to a production method for obtaining an inorganic molded article having excellent strength, water resistance, thermal shock resistance and dimensional stability as compared with a cement-based material or a calcium silicate-based material.

[0002]

2. Description of the Related Art Conventionally, cement boards, calcium silicate boards, and the like have been widely used as building materials or structural materials or members for applications requiring nonflammability. However, cement-based materials and calcium silicate-based materials contain water of hydration because water is involved in the hardening of these materials. Therefore, when the cement-based material and the calcium silicate-based material are exposed to a temperature higher than the temperature at which the hydration water is vaporized,
Cracks may cause a large change in dimensions or a significant decrease in strength.

A curable composition containing phosphoric acid and / or a phosphate and various metal compounds as an inorganic material resistant even at such a high temperature, and a curable composition obtained by curing the curable composition. Inorganic materials have been proposed. Also, various molded products, structural materials and building materials in which the inorganic material is reinforced with a reinforcing material have been proposed.

For example, JP-A-55-51768 discloses that (a) a natural product or composition containing at least one of alumina, silica, or both, or glass, and (b) phosphoric acid or A low-temperature fired inorganic composition has been proposed in which a reinforcing material capable of withstanding a firing temperature at an upper limit of 750 ° C. is added to an inorganic molding material comprising a mixture with a salt thereof, and glass fiber, rock wool, metal Fibers, carbon fibers, and mixtures thereof are mentioned.

Further, Japanese Patent Publication No. 59-3958 discloses that
An aqueous slurry mixture obtained by mixing an appropriate amount of a fast-acting curing agent and a slow-acting curing agent with an inorganic film-forming material as a main component was impregnated and applied to a regular fiber base material such as paper, woven fabric, nonwoven fabric, and mat. Thereafter, a method for producing a flexible inorganic incombustible molded article to be cured is disclosed, wherein a metal phosphate such as aluminum phosphate and aluminum polyphosphate is used as an inorganic film-forming agent, and magnesium oxide, zinc oxide is used as a curing agent. , Aluminum hydroxide, calcium hydroxide, calcium silicate and the like, and glass fiber as a fiber base material.

Further, by suppressing the reaction between phosphoric acid or phosphate and various metal compounds in the curable composition, an increase in the viscosity of the curable composition is suppressed, and the impregnation into the inorganic reinforcing material is improved. To improve the mechanical strength of the molded product,
In addition, JP-A-4-317403 discloses that an organic liquid buffer is added to a curable composition for the purpose of improving workability and moldability when obtaining a molded product, Further, carboxylic acids, amines, urea and the like are mentioned as the organic liquid buffer.

[0007]

However, the above 3)
In the technology related to conventional inorganic materials using phosphoric acid or phosphate and various metal compounds represented by the above patents, the quantitative ratio of phosphate ion to metal ion constituting phosphate and curing The quantitative ratio between phosphate ions derived from phosphoric acid or phosphate and metal ions derived from the curing agent (metal compound) in the neutralizing composition has not been studied in detail according to various uses and production methods. In addition, there is a problem that the water resistance of the obtained inorganic material is low, that is, water is easily absorbed, and the degree of dimensional change at the time of water absorption is sometimes increased.

In the techniques disclosed in JP-A-55-51768 and JP-A-4-317403, a preliminary treatment of phosphoric acid and / or phosphate and a curing agent thereof is performed. Since it is blended into the curable composition without being applied, it is at least 300 ° C.
(750 ° C.), it is necessary to heat and cure the curable composition at a relatively high temperature, so that energy costs are high, heating and slow cooling require a long time, and productivity is low. There is a problem that a compatible heating facility is required.

Furthermore, carboxylic acids and amines used as organic liquid buffers in the technique disclosed in Japanese Patent Application Laid-Open No. 4-317403 do not vaporize or decompose when heated to complete the curing of the curable composition. Therefore, it remains inside the cured composition, that is, the molded article. When carboxylic acids remain inside the molded article, there is a problem that the molded article has low water resistance.

Further, in the curable composition disclosed in JP-A-4-317403, 0.25 to 1 mol of an organic liquid buffer is added to 1 mol of phosphoric acid. Is converted into a weight ratio for each type of organic liquid buffer, which corresponds to adding about 15 to 155 parts of the organic liquid buffer to 100 parts of phosphoric acid (concentration converted to 100%). As described above, when the organic liquid buffer is used in a relatively large amount with respect to the phosphoric acid, since a large amount of the organic substance remains in the obtained molded article, the heat resistance of the molded article is reduced. There's a problem.

Therefore, an object of the present invention is to provide a high strength,
An inorganic molded article having excellent water resistance, heat resistance, thermal shock resistance and dimensional stability can be obtained, and a curable composition using phosphoric acid and / or a metal phosphate and a curing agent thereof can be obtained. An object of the present invention is to provide a method for producing an inorganic molded article which can be heated and cured at a relatively low temperature.

[0012]

Means for Solving the Problems To solve the above-mentioned problems, the method for producing an inorganic molded article of the present invention is as follows:
It is characterized by including the step (5). (1) A phosphoric acid aqueous solution containing 10 to 80% by mass of P ₂ O ₅ and 3
The ratio (M / P) of the number of moles (P) of the phosphate ions (PO ₄ ³⁻ ) and the number of moles (M) of the metal ions contained in each of the hydroxides of the monovalent metal to 1 / A step of mixing 3 <M / P ≦ 1/2 and reacting phosphoric acid with a metal hydroxide to obtain an aqueous solution or aqueous dispersion of a metal acid phosphate. (2) at least one selected from the group consisting of an aqueous solution or aqueous dispersion of the acidic metal phosphate, a metal hydroxide, a basic metal oxide, and a composite metal oxide containing the basic metal oxide as a component; The ratio of the total valence of phosphate ions to the total valence of metal ions contained in each of the curing agents (A)
Obtaining a curable composition mixed such that 1 <A ≦ 5. (In the above equation, A = (M ₀ × 3 + M ₁ × n ₁ + M ₂ × n
₂ +...) / (P ₀ × 3), M ₀ is the number of moles of metal ions contained in the acid metal phosphate, P ₀ is the number of moles of phosphate ions contained in the metal acid phosphate, M _1, M ₂ ... represents the number of moles of each metal ion contained in the curing agent, n _1, n ₂
Represents the valence of each metal ion corresponding to the above M ₁ , M ₂ . (3) A step of obtaining a molding material by combining 100 parts by mass of the curable composition with 5 to 100 parts by mass of an inorganic reinforcing material. (4) A step of adjusting the amount of water contained in the molding material to be less than 10% by mass. (5) The molding material is molded into a desired shape,
A step of heating to a temperature of 150 ° C. to complete the curing.

According to the method for producing an inorganic molded article of the present invention, an acidic metal phosphate obtained by adjusting a specific ratio between a phosphate ion and a metal ion is used. Since a curable composition in which a salt and its curing agent are blended in a specific quantitative ratio is used, phosphate ions or metal ions become excessive and remain after the curing reaction, or a reaction of the curable composition. -Insufficient curing is prevented, and the resulting inorganic molded article has high water resistance.

Further, according to the method for producing an inorganic molded article of the present invention, an aqueous solution or aqueous dispersion of a specific acidic metal phosphate is used, that is, trivalent acid which is one type of phosphoric acid and its hardener. Since the reaction and curing temperature can be made relatively low at 120 to 150 ° C. and the curing time can be shortened by previously promoting the reaction of the metal with the hydroxide of the metal, the resulting inorganic system It is possible to improve the productivity of molded articles and the economical efficiency such as energy cost during production.

Further, phosphoric acid and its curing agent, 3
The reaction between the acidic metal phosphate and the curing agent on the surface and inside of the curable composition is achieved by using the acidic metal phosphate which has been preliminarily reacted with the hydroxide of the multivalent metal. Since the degree of the reaction cannot be greatly changed, only the surface portion where moisture is easily vaporized does not cure first, and the amount of condensed water (by-product) generated as the reaction proceeds is reduced. . Therefore, the internal water vaporized by heating is easily released to the outside, and the amount of condensed water generated by the reaction is small, so that cracks occur during the curing of the composition or the inside of the obtained molded article No voids are formed.

Further, by combining the curable composition and the inorganic reinforcing material in the above-mentioned specific ratio, the mechanical strength, water resistance, heat resistance, and dimensional stability are extremely superior to those of conventional products. And can be used for building materials or various structural materials and members that require industrial heat resistance.

Further, before the molding material is formed into a desired shape, the water content is adjusted to be less than 10% by mass, so that the handleability of the molding material is improved.
In a subsequent step, the molded article does not expand due to rapid vaporization of water.

In a preferred embodiment of the present invention, the curable composition preferably further contains 0.1 to 10 parts by mass of urea based on 100 parts by mass of the metal acid phosphate. According to this, since the curable composition further contains urea in a specific quantitative ratio in addition to the acidic metal phosphate and the curing agent thereof, the reaction between the acidic metal phosphate and the curing agent is suppressed to cure the composition. The viscosity increase of the curable composition is suppressed, and the inorganic reinforcing material, particularly the impregnation of the curable composition into the inorganic fibers becomes easy and good,
The resulting inorganic molded article has good mechanical strength, and there is no problem that urea remains in the molded article.

It is preferable that the curing agent contains one having an average particle diameter of 5 μm or less in an amount of 30% by mass or more of the whole curing agent. According to this, the matrix of the obtained molded article becomes dense, and the mechanical strength of the molded article becomes good.

Further, the curing agent has an average particle diameter of 20 μm.
It is preferable to contain the above-mentioned components in an amount of 0.1 to 10% by mass of the entire curing agent. According to this, since the water contained in the curable composition is easily released when vaporized, no void is formed in the molded article.

Further, it is preferable that the inorganic reinforcing material is an inorganic fiber or a whisker. According to this, the reinforcing effect can be enhanced without impairing the heat resistance and the like.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the following description, unless otherwise specified, the unit “parts” means “parts by mass”, and the unit “%” means “mass percentage”.

In the present invention, the curable composition refers to a composition containing an acidic metal phosphate, a curing agent thereof, and other components to be added as required in a predetermined ratio. In the present invention, the matrix mainly means a portion where the acidic metal phosphate and its hardener have reacted and hardened, and means a portion excluding the inorganic reinforcing material.

The acidic metal phosphate in the method for producing an inorganic molded article of the present invention is prepared by mixing an aqueous phosphoric acid solution and a hydroxide of a trivalent metal in a specific quantitative ratio, and allowing them to react. It is obtained in the form of an aqueous solution or an aqueous dispersion.

As the above phosphoric acid aqueous solution, a commercially available 75%
Phosphoric acid (containing 54% P ₂ O ₅ ), 89% phosphoric acid (P
₂ O ₅ containing 64%) or polyphosphoric acid (P ₂ O ₅
5%) or a solution obtained by diluting phosphorus pentoxide with water, and there is no particular limitation on the raw material. However, when phosphorus pentoxide is used, heat generation due to hydrolysis at the time of dilution with water is increased, which may cause bumping or the like and impair the safety at the time of operation, so that it is not preferable.

From the viewpoint that the flowability of the curable composition at the time of molding is improved and the structure of the obtained molded article can be made dense, the aqueous phosphoric acid solution is composed of P ₂
O ₅ and it is necessary to use those containing 10% to 80%, it is preferable to use a phosphoric acid aqueous solution containing P ₂ O ₅ 40 to 60%.

10% of P ₂ O ₅ contained in the phosphoric acid aqueous solution
When the water content is less than 3, the amount of water contained in the curable composition obtained by mixing and reacting with a hydroxide of a trivalent metal to form an acidic metal phosphate and then mixing this with a curing agent is large. Therefore, the time required for drying and curing of the curable composition is prolonged, thereby impairing the productivity of the inorganic molded article, or increasing the amount of water contained in the molded article, and causing the molded article Swelling and cracks are likely to occur.

On the other hand, if the P ₂ O ₅ contained in the aqueous phosphoric acid solution exceeds 80%, the reaction proceeds rapidly during the reaction with the hydroxide of the trivalent metal, and the resulting acidic phosphorus In some cases, a gel-like substance is generated in the acid metal salt, which impairs the fluidity of a curable composition obtained by mixing this with a curing agent, resulting in poor impregnation into the inorganic reinforcing material. In some cases, the surface smoothness and mechanical strength of the inorganic molded article are impaired.

The trivalent metal hydroxide includes, for example, aluminum hydroxide and iron hydroxide.

The aqueous solution or aqueous dispersion of the acidic metal phosphate can be obtained by mixing the aqueous phosphoric acid solution and the hydroxide of the trivalent metal and reacting them while stirring. The mixing ratio of the aqueous phosphoric acid solution and the hydroxide of the trivalent metal is determined according to the phosphate ion (PO
_It is necessary that the ratio (M / P) of the number of moles (P) of ₄ ^3- ) to the number of moles (M) of the metal ion be 1/3 <M / P ≦ 1/2, and Is preferably such that 1 / 2.7 <M / P ≦ 1 / 2.2.

When the ratio (M / P) of the number of moles of phosphate ions to the number of moles of metal ions becomes 1/3 or less, the obtained aqueous solution or aqueous dispersion of the acidic metal phosphate and the curing agent A long time is required to cure the curable composition prepared by mixing the acid and the present invention by using an acid phosphate metal salt in which phosphoric acid is reacted with a hydroxide of a trivalent metal in advance. Does not appear. In addition, curing is insufficient, and the degree of moisture absorption and water absorption of the molded product increases.

On the other hand, when the ratio (M / P) of the number of moles of phosphate ions to the number of moles of metal ions exceeds 1/2, phosphoric acid and a hydroxide of a trivalent metal are mixed and reacted. At this time, the reaction may proceed excessively, and a precipitate that is insoluble in water or that cannot be dispersed in water may be generated. Since this precipitate is a component that does not react with the curing agent, if it is mixed into the curable composition, the overall reaction and curing will be insufficient, or the water resistance and mechanical properties of the resulting inorganic molded article will be poor. Or the target strength is reduced.

In the reaction between phosphoric acid and a hydroxide of a trivalent metal, the reaction is initiated only by mixing the two.
Since the temperature of the mixture rises to 80 to 90 ° C. due to the heat of the reaction and the reaction proceeds, the reaction is completed by stirring for 30 minutes to 3 hours. At this time, in order to make the reaction sufficient and to shorten the reaction time, 80 to 150
Stirring may be performed by heating or maintaining the temperature up to the temperature of ° C. The concentration (solid content) of the aqueous solution or aqueous dispersion of the metal acid phosphate obtained as described above is preferably 75% or less from the viewpoint of handling when mixing with the curing agent.

The aqueous solution or aqueous dispersion of the metal acid phosphate obtained as described above and its curing agent are reacted and cured by mixing and heating to form a matrix of the obtained inorganic molded article. Form. As a curing agent for the acidic metal phosphate, a metal compound selected from a metal hydroxide, a basic metal oxide, and a composite metal oxide containing a basic metal oxide as a component can be used. , One of these can be used alone, or two or more can be used in combination.

Among the above metal compounds, metal hydroxides include aluminum hydroxide, calcium hydroxide and magnesium hydroxide, and basic metal oxides include aluminum oxide, magnesium oxide, zinc oxide and calcium oxide. and calcium silicate as a composite metal oxide containing a basic metal oxide as a component (wollastonite), calcium aluminate (alumina cement), kaolinite, cordierite (2MgO · 2Al ₂ O ₃
.5SiO ₂ ), magnesite, talc and the like.

A curable composition can be obtained by mixing the above-mentioned curing agent and the above-mentioned aqueous solution or aqueous dispersion of the acidic metal phosphate. At this time, mixing is performed so that the ratio (A) of the total valence of the phosphate ions to the total valence of the metal ions contained therein is 1 <A ≦ 5.

In the above equation, A = (M ₀ × 3 + M ₁ × n
₁ + M ₂ × n ₂ +...) / (P ₀ × 3), where M ₀ is the number of moles of metal ions contained in the acidic metal phosphate, P
₀ represents the number of moles of phosphate ions contained in the acidic metal phosphate, M ₁ , M ₂ ... Represent the number of moles of each metal ion contained in the curing agent, and n ₁ , n ₂ . The valence of each metal ion corresponding to ₁ , M ₂ ...

When the ratio (A) of the total valence of phosphate ions to the total valence of metal ions (A) is 1 or less, an inorganic molded article obtained by molding, heating and curing the curable composition is used. Unreacted acidic metal phosphate remains, and not only does not provide sufficient mechanical strength, but also impairs the water resistance of the molded article. On the other hand, when the above ratio (A) exceeds 5, the amount of the acidic metal phosphate relative to the amount of the curing agent decreases, and the fluidity of the curable composition at the time of molding decreases. Impregnation or molding into a desired shape becomes difficult, the appearance of the obtained molded article is impaired, or the matrix of the molded article becomes coarse, and sufficient mechanical strength cannot be obtained.

In the present invention, the aqueous solution or aqueous dispersion of the acidic metal phosphate is mixed with the curing agent so that the ratio (A) is 1.5 to 2.5. More preferably, the composition is a curable composition. Further, the solid content of the curable composition is preferably 50 to 75%.

In the case where the above-mentioned curing agent is used, those having an average particle diameter of 5 μm or less constitute 3% of the entire curing agent.
Preferably, it is contained at 0% or more. Average particle size is 5
When 30% or more of the curing agent of μm or less is contained, the matrix of the obtained molded article becomes dense, the adhesion between the reinforcing material and the matrix becomes good, and the mechanical strength of the molded article becomes good. However, if the amount of the curing agent having an average particle diameter of 5 μm or less is less than 30% by mass, the resulting molded article may lack the denseness of the matrix.

The above-mentioned curing agent has an average particle diameter of 20
It is preferred that those having a size of at least μm are contained in 0.1 to 10% of the entire curing agent. When the curing agent having an average particle diameter of 20 μm or more is contained in an amount of 0.1 to 10%, when water contained in the curable composition is vaporized, the water is easily released to the outside, and the vaporized water is released. Since the expansion of the matrix or the generation of voids due to the difficulty of the formation can be suppressed, the mechanical strength of the obtained inorganic molded product is improved. The curing agent having an average particle diameter of 20 μm or more can obtain its effect by being contained even in a small amount. It may not be dense.

In the present invention, the purpose is to improve the mechanical strength and appearance of the inorganic molded product, to reduce the weight and cost of the inorganic molded product, and to give the molded product a design. In addition to the above components, various additives can be added to the curable composition. As such additives, reaction suppressing components, lightweight aggregates, fillers, pigments and the like can be used. Urea is used as a reaction-inhibiting component, shirasu balloon, glass balloon, perlite, etc., as lightweight aggregates, silica sand, silica fume, glass powder, clay, etc. mainly containing an acidic oxide as a filler, and oxidized as a pigment. Titanium, zinc oxide, phthalocyanine, red stalk,
Mapico etc. can be illustrated. These materials may be appropriately selected according to each purpose, and an appropriate amount may be used.

Particularly, when the reactivity between the acidic metal phosphate and the curing agent contained in the curable composition is high, urea as a reaction-inhibiting component is added to the curable composition among the above additives. It is preferred to add. For example, urea is added to the curable composition immediately after mixing the aqueous solution or aqueous dispersion of the acidic metal phosphate and its curing agent. As a result, the two amino groups of urea interact with the hydroxyl groups of the acidic metal phosphate to suppress the reaction between the acidic metal phosphate and the curing agent, thereby increasing the viscosity of the curable composition. Can be suppressed. As a result, since the fluidity of the curable composition is not impaired, the impregnation of the fibrous reinforcing material is facilitated.

In this case, the amount of urea used is preferably 0.1 to 10 parts of urea based on 100 parts (as solid content) of the acidic metal phosphate in the curable composition. If the amount of urea is less than 0.1 part, the effect of suppressing the reaction of urea is insufficient, while if the amount of urea exceeds 10 parts, when heating is performed to cure the curable composition. In addition, since the amount of ammonia and carbon dioxide generated by the decomposition of urea increases, voids are formed in the inorganic molded product, and its mechanical strength and the like are reduced. The amount of urea used is more preferably 0.5 to 5 parts based on 100 parts of the acidic metal phosphate.

As the inorganic reinforcing material used in the present invention, the same reinforcing materials as those used in conventional inorganic materials can be used, and among them, inorganic fibers and whiskers are preferably used. In particular, inorganic fibers are preferably used because of their versatility. Glass fibers, ceramic fibers, carbon fibers and the like can be used as the inorganic fibers, and aluminum borate whiskers and the like can be used as the whiskers.

The glass composition of the above glass fiber is A
Glass, E glass, ECR glass, S glass, AR glass and the like can be exemplified. Examples of the ceramic fibers include alumina fibers, silicon-alumina fibers, and silicon nitride fibers. The above-mentioned inorganic fibers can be used in any form of short fibers and long fibers, and curable inorganic fibers in various forms, including inorganic fibers processed into the form of mats, woven fabrics, nonwoven fabrics, papers, etc. It can be appropriately selected and used according to the processing method of the composition, the use of the molded article, and the like. As the inorganic fiber, it is particularly preferable to use a glass fiber of E glass composition which is inexpensive and widely used. As the glass fiber having the E glass composition, a glass fiber processed into a short fiber such as milled fiber or chopped strand, a continuous fiber such as yarn or roving, a mat, a woven fabric, a nonwoven fabric, or the like can be used.

The above-mentioned inorganic reinforcing material can be used singly or in combination of two or more by appropriately selecting the quality and form. The inorganic reinforcing material is used in an amount of 5 to 100 parts based on 100 parts (as a solid content) of the curable composition. When the amount of the inorganic reinforcing material is less than 5 parts, the mechanical strength of the inorganic molded article becomes insufficient. On the other hand, when the amount of the inorganic reinforcing material exceeds 100 parts, the composition with respect to the reinforcing material is Because of the shortage, the matrix becomes coarse, and the mechanical strength of the inorganic molded article also becomes insufficient. The amount of the inorganic reinforcing material used is 15 to 80 with respect to 100 parts of the curable composition.
Is more preferable.

Each step in the method for producing an inorganic molded article of the present invention is not particularly limited, but specific examples can be shown as follows.

First step: Using a reaction device such as a reaction vessel equipped with a heating device, a phosphoric acid aqueous solution and
An aqueous solution or dispersion of an acidic metal phosphate is obtained by mixing and reacting with a hydroxide of a valent metal.

Second step: The curable composition is obtained by mixing the aqueous solution or aqueous dispersion of the acidic metal phosphate salt obtained in the first step with the curing agent in the above-described ratio. At this time, various additives such as urea are further added as needed.

Third step: The curable composition obtained in the second step and the inorganic reinforcing material are combined to obtain a molding material for molding into a desired shape in a later step. The method of combining the curable composition and the inorganic reinforcing material may be appropriately selected from the following methods (1) to (4) according to the molding method employed in the subsequent step or the use of the obtained inorganic molded article. However, the present invention is not limited to these methods.

A method of using a mat-like inorganic reinforcing material, impregnating the mat-like reinforcing material in a bath of the curable composition and pulling out the mat-like reinforcing material, and then impregnating and attaching the composition to the mat-like reinforcing material.

The curable composition is previously made to have a high viscosity to some extent, applied to the surface of a carrier material such as a resin film, and a roving is cut to a predetermined length as a reinforcing material on the applied composition. Or a method in which chopped strands that have been cut in advance are scattered, and the reinforcing material is impregnated by compressing the chopped strands via a carrier material from above.

A method in which a curable composition is used in place of plastic (resin) by a hand lay-up method or a spray-up method as employed in the production of glass fiber reinforced plastic.

As the inorganic reinforcing material, whiskers or
A method in which short fiber inorganic fibers such as milled fibers and chopped strands are used, and the curable composition and the inorganic reinforcing material are kneaded using a dispersion mixer such as a kneader.

In the above method, the composite of the curable composition and the inorganic fiber as the inorganic reinforcing material is formed on a mold having a desired shape, and the molding material is also molded. preferable.

Fourth step: The molding material obtained in the third step is made easier to handle up to the next step, and the amount of water vaporized at the completion of molding and curing is suppressed to reduce In order to prevent expansion of the molded article due to rapid vaporization of water, the amount of water contained in the molding
Adjust so that it is less than%. In the case where the composition and the molding of the curable composition and the inorganic fiber are performed by the above method of the third step, the mold is dried until most of the moisture in the curable composition is vaporized, and then the mold is released. Is preferred. In order to adjust the moisture of the molding material to the above range, 80 to 1
It is preferable to dry by heating at a temperature of 00 ° C. for 2 to 8 hours.

Fifth step: The molding material after adjusting the water content is formed into a desired shape such as a flat plate, a corrugated plate, or an irregular shape appropriately set according to the use of the obtained molded product. Alternatively, after molding, the composition is heated to a temperature of 120 to 150 ° C. to completely react the acidic metal phosphate contained in the molding material with its curing agent, and the curing is completed to obtain an inorganic molded article. At this time, it is preferable to heat in a heating machine for about 30 minutes to 4 hours. In the case where the obtained molded article has a relatively simple shape such as a flat plate, the molding in the fifth step is performed prior to the adjustment of the water content in the fourth step, and then the two-step molding is performed. By heating under the temperature condition, the adjustment of the water content in the fourth step and the reaction / curing in the fifth step may be continuously performed.

The molding of the molding material in the fifth step is performed by a device capable of performing only pressurization or simultaneous pressurization and heating, such as a mold press, a flat plate press, a belt press, and a roll press. be able to. Furthermore,
The molding material obtained by the method of the second step can be molded by a transfer molding method employed when producing glass fiber reinforced plastic.

[0060]

The present invention will be described in more detail with reference to the following examples. I. Preparation of Aqueous Solution or Aqueous Dispersion of Metallic Acid Phosphate An aqueous solution of phosphoric acid and a hydroxide of a trivalent metal are charged into a reaction vessel equipped with a steam heating device at a ratio shown in Table 1 and then cooled to room temperature. And reacted for 2 hours to obtain an aqueous solution or aqueous dispersion (phosphate 1 to phosphate 6) of an acidic metal phosphate. At this time, the temperature inside the reactor is 90 due to the heat generated by the reaction.
° C.

The ratio (M / P) between the number of moles of phosphate ions (P) and the number of moles of metal ions (M) in each of phosphates 1 to 6 is shown in Table 1. It is as follows. Further, the M / P of the first aluminum phosphate used in the composition 11 (Comparative Example 11) described later is 1/3.

[0062]

[Table 1]

B. Production of Samples of Inorganic Molded Articles of Examples 1 to 12, Comparative Examples 1 to 6, and Comparative Examples 10 to 11 According to the method shown below, each raw material was blended as shown in Table 2 to obtain a curable composition. A curable composition was prepared, and the curable composition was combined with an inorganic reinforcing material (using chopped strands of inorganic fibers) in the ratios shown in Tables 3 and 4 to obtain a molding material, thereby obtaining an inorganic molded article. .

First, an aqueous solution or aqueous dispersion of an acidic metal phosphate obtained as described above or an aqueous solution of aluminum monophosphate and its curing agent and other components were added in a dissolving agent ratio shown in Table 2. To obtain a curable composition. The ratio (A) between the total valence of phosphate ions and the total valence of metal ions in each curable composition is shown in Table 2
As shown in FIG.

Next, the curable composition is applied to the surface of a PET (polyethylene terephthalate) resin film as a carrier material, chopped inorganic fibers are spread thereon, and the curable composition is further placed thereon. After placing the PET resin film applied on the surface such that the surface on which the composition is applied is in contact with the inorganic fiber, the material is compressed by a mesh belt press to impregnate the inorganic fiber with the curable composition, and the both are impregnated. The composite was made into a sheet-like molding material. This molding material is heated and dried in a dryer at a temperature of 80 ° C.,
Moisture content of the molding material is 5% of the molding material
It was adjusted to the extent. This molding material was heated at a temperature of 140 ° C. under a pressure of 3.43 MPa using a flat plate press.
After completion of the curing by heating while performing pressure molding under the condition of a pressing time of 1 hour, it was naturally cooled to obtain a flat inorganic molded article.

C. Production of Samples of Inorganic Molded Articles of Examples 13 to 15 and Comparative Examples 7 to 9 According to the method shown below, each raw material was blended as shown in Table 2 to prepare a curable composition, and this curing was performed. The conductive composition and the inorganic reinforcing material (using aluminum borate whisker or milled fiber of E glass fiber) were combined at the ratios shown in Tables 3 and 4 to obtain a molding material to obtain an inorganic molding.

First, the aqueous solution or aqueous dispersion of the acidic metal phosphate obtained as described above, its hardener, inorganic reinforcing material, water and other components are shown in Tables 2, 3 and 4. The mixture was kneaded using a kneader at the above ratio to obtain a molding material in which the curable composition and the inorganic reinforcing material were kneaded. At this time, the amount of water to be mixed was appropriately adjusted while monitoring the state of kneading in a kneader so that the obtained molding material did not flow when left naturally. The ratio (A) between the total valence of phosphate ions and the total valence of metal ions in each curable composition is as shown in Table 2.

Next, the above-mentioned molding material was pressed at a temperature of 80 ° C., a pressure of 3.43 MPa and a pressing time of 2 using a flat plate press.
The mixture was pressure-molded under the conditions of minutes to obtain a plate-like semi-cured material.
The semi-cured material thus obtained is dried in a dryer at a temperature of 80.degree.
After drying by heating for one hour,
After heating to complete the curing, the mixture was naturally cooled to obtain an inorganic molded article.

[0069]

[Table 2]

[0070]

[Table 3]

[0071]

[Table 4]

D. Samples of other inorganic materials Glass fiber reinforced gypsum board as Comparative Example 12, asbestos slate board as Comparative Example 13, cosmetic asbestos slate board as Comparative Example 14, and alkali-resistant glass fiber reinforced concrete board as Comparative Example 15 for comparative evaluation Was used as a sample.

E. Test Examples Examples 1 to 15 and Comparative Example 1 were prepared by the following method.
１５15 samples were evaluated. Tables 5 and 6 show the results.
Shown in・ Thickness and bulk specific gravity: method according to JIS A 5430 ・ Bending strength: method according to JIS A 1408 (normal condition, temperature 3)
The measurement was performed after heating for 24 hours in an atmosphere of 00 ° C. and after immersing in water at 15 ° C. for 24 hours. Water absorption: The ratio between the weight increased by immersing the sample in water at 15 ° C. for 24 hours and the weight before immersion was calculated. -Dimensional change rate: 24 samples in air at a temperature of 60 ° C
After heating for a period of time and then immersing in water at a temperature of 15 ° C. for 24 hours, followed by heating in air at a temperature of 105 ° C. for 24 hours, the mixture was naturally cooled to room temperature. The change in the length of the sample before and after performing these heating and immersion was measured with a contact gauge, and the ratio of the amount of change to the original size was calculated. Surface condition: After heating the sample in an atmosphere at a temperature of 400 ° C. for one hour, the surface condition was visually observed to determine whether cracks, warpage, and the like occurred.

[0074]

[Table 5]

[0075]

[Table 6]

As can be seen from Tables 5 and 6, the inorganic molded products of Examples 1 to 15 obtained by the production method of the present invention have a higher bending strength than the inorganic molded products of Comparative Examples 1 to 11. And the water absorption and dimensional change are small. Also,
In the glass fiber reinforced gypsum board, the asbestos slate board, the asbestos slate board and the alkali glass fiber reinforced concrete board of Comparative Examples 12 to 15, the water absorption rate and the dimensional change rate are extremely large, and cracks occur when heated at a high temperature. However, the inorganic molded articles of Examples 1 to 15 according to the present invention have a small water absorption rate and a small dimensional change rate, and have no change in the surface state even when heated at a high temperature.

In the step of obtaining an aqueous solution or aqueous dispersion of an acidic metal phosphate, the ratio (M / P) of the number of moles of phosphate ions (P) to the number of moles of metal ions (M) is determined according to the present invention. When the phosphoric acid aqueous solution and the trivalent metal hydroxide are used in a range outside the specified range (1/3 <M / P ≦ 1/2), it is understood that a normal molded product cannot be obtained. . That is, M
In Comparative Examples 3 and 8 where / P is 1/3 or less (the number of moles of phosphate ions is large), the cured product is insufficiently cured, the degree of moisture absorption is increased, and the M / P is 1
In Comparative Example 4 in which the ratio exceeds / 2 (the number of moles of phosphate ions is small), it can be seen that the molded article becomes extremely brittle so that it cannot be handled.

In the curable composition, the ratio (A) of the total valence of phosphate ions to the total valence of metal ions is out of the specified range (1 <A ≦ 5) according to the present invention. When the aqueous solution or the aqueous dispersion of the metal phosphate and the curing agent thereof are blended (Comparative Example 5, Comparative Example 6, and Comparative Example 10), the bending strength of the molded product is reduced, It can be seen that the dimensional change rate becomes large and the molded product becomes extremely brittle so that it cannot be handled.

Further, among the conventional inorganic materials mainly containing phosphoric acid or phosphate and its hardener, the case where aluminum phosphate monobasic, which is most commonly used, was used (Comparative Example 11) It can be seen that in Example 1, the bending strength of the molded article after immersion in water was low, the water absorption rate and the dimensional change rate were large, that is, the water resistance was poor. This is considered to be because, when aluminum monophosphate is used, the curing is insufficient in the prescribed range of the curing temperature (120 to 150 ° C.) in the present invention.

Furthermore, when the inorganic reinforcing material is used in a range outside the quantitative ratio of the curable composition and the inorganic reinforcing material specified in the present invention (5 to 100 parts with respect to the former 100 parts). Can also be problematic. That is,
When the amount ratio of the inorganic reinforcing material is small (Comparative Examples 1 and 7), the bending strength of the molded product is low, and when the amount ratio of the inorganic reinforcing material is large (Comparative Examples 2 and 9), the production is It turns out that a molded article cannot be obtained due to a problem on the way.

[0081]

As described above, according to the present invention, a metal salt of an acidic phosphoric acid, which is obtained by preliminarily reacting phosphoric acid with a hydroxide of a trivalent metal which is a kind of a curing agent thereof, is used. Used as a component of the curable composition, further, when obtaining an aqueous solution or aqueous dispersion of this acidic metal phosphate, the ratio between the number of moles of phosphate ions and the number of moles of metal ions is specified in a specific range. And when an aqueous solution or aqueous dispersion of this acidic metal phosphate and a curing agent thereof are blended to obtain a curable composition, the total valency of the phosphate ions and the total Since the ratio with the valence is specified in a specific range, 12
An inorganic molded article can be obtained by molding and curing at a low temperature of 0 to 150 ° C. Therefore, the curable composition does not cause cracks during heating and curing, and voids are not formed inside the obtained molded article,
Further, the water resistance of the molded article does not decrease due to insufficient curing.

Further, the inorganic molded article obtained by the production method of the present invention has excellent mechanical strength, water resistance, dimensional stability and heat resistance as compared with conventional ones. It can be used for materials, industrial structural materials or members, and the like. For example, it can be used as an insulating plate of a heat press forming apparatus, an interior material or an exterior material of a building such as a house, an exterior material for a house reform, or the like.

Further, it is also possible to use a molded article obtained by laminating and integrating the inorganic molded article obtained by the production method of the present invention and another material. Examples of other materials to be laminated include a foamed resin plate such as a foamed polystyrene resin, a synthetic resin decorative sheet such as a melamine resin sheet, wood, and a concrete plate. A method of joining an inorganic molded article and another material using an adhesive, or a semi-cured material obtained by press-molding a molding material and the above-mentioned other material in a laminated state, and using this semi-cured material. At the same time as heating to complete the curing, the method of joining with another material by the adhesive force of the curable composition contained in the semi-cured material is appropriately selected according to the use of the product, the quality of the other material to be selected, and the like. .

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Claims (5)

[Claims] 1. A method for producing an inorganic molded article, comprising the following steps (1) to (5). (1) A phosphoric acid aqueous solution containing 10 to 80% by mass of P ₂ O ₅ and 3
The ratio (M / P) of the number of moles (P) of the phosphate ions (PO ₄ ³⁻ ) and the number of moles (M) of the metal ions contained in each of the hydroxides of the monovalent metal to 1 / A step of mixing 3 <M / P ≦ 1/2 and reacting phosphoric acid with a metal hydroxide to obtain an aqueous solution or aqueous dispersion of a metal acid phosphate. (2) at least one selected from the group consisting of an aqueous solution or aqueous dispersion of the acidic metal phosphate, a metal hydroxide, a basic metal oxide, and a composite metal oxide containing the basic metal oxide as a component; The ratio of the total valence of phosphate ions to the total valence of metal ions contained in each of the curing agents (A)
Obtaining a curable composition mixed such that 1 <A ≦ 5. (In the above equation, A = (M ₀ × 3 + M ₁ × n ₁ + M ₂ × n
₂ +...) / (P ₀ × 3), M ₀ is the number of moles of metal ions contained in the acid metal phosphate, P ₀ is the number of moles of phosphate ions contained in the metal acid phosphate, M _1, M ₂ ... represents the number of moles of each metal ion contained in the curing agent, n _1, n ₂
Represents the valence of each metal ion corresponding to the above M ₁ , M ₂ . (3) A step of obtaining a molding material by combining 100 parts by mass of the curable composition with 5 to 100 parts by mass of an inorganic reinforcing material. (4) A step of adjusting the amount of water contained in the molding material to be less than 10% by mass. (5) The molding material is molded into a desired shape,
A step of heating to a temperature of 150 ° C. to complete the curing. 2. The method for producing an inorganic molded article according to claim 1, wherein the curable composition further contains 0.1 to 10 parts by mass of urea based on 100 parts by mass of the metal acid phosphate. 3. The curing agent according to claim 1, wherein the curing agent contains an average particle size of 5 μm or less in an amount of 30% by mass or more of the entire curing agent.
The method for producing an inorganic molded article according to the above. 4. The curing agent according to claim 1, wherein said curing agent contains particles having an average particle diameter of 20 μm or more in an amount of 0.1 to 10% by mass of the whole curing agent.
4. The method for producing an inorganic molded article according to any one of items 1 to 3. 5. The method according to claim 1, wherein the inorganic reinforcing material is an inorganic fiber or a whisker.