JP2000264701A - Lightweight inorganic molding and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightweight inorganic molding having high strength and excellent in surface properties by using specified proportions of cement, woody fibers of a specified shape and amorphous silica-base inorganic expanded bodies. SOLUTION: The lightweight inorganic molding consists essentially of 20-60 wt.% cement, 5-25 wt.% woody fibers having 1.5-8 mm average length and 0.2-0.9 mm average width and 18-60 wt.% amorphous silica-base inorganic expanded bodies. Cement, amorphous silica-base inorganic expanded bodies and woody fibers are dry-mixed to obtain a mixture in which the inorganic expanded bodies and cement are uniformly mixed between the woody fibers, 40-80 wt.% water is added to the mixture and they are mixed, deposited in a mat shape, press-molded and primarily cured to hydrate and harden the cement. Secondary curing is then carried out in an autoclave to allow calcium in the cement to react with the amorphous silica in the inorganic expanded bodies. By this reaction, a calcium silicate compound is formed and strength is exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The object of the present invention is to provide a lightweight inorganic molded article having high strength and excellent surface properties and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Publication No. 5-69785, there is an inorganic molded body using a wood fiber bundle to enhance the reinforcing effect.
In this inorganic molded body, a relatively long fiber bundle having an average length of 10 to 30 mm is used in order to maintain bulkiness. However, the longer the wood fiber bundle is, the larger the diameter and the more rigid it is, so that the surface smoothness and sharp embossing property, which are important for the exterior material, are impaired.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. Hei 3-218955, there is an inorganic molded article to which pearlite (inorganic foam) is added together with wood fibers to reduce the weight of a plate material. However, if a large amount of pearlite is added, the strength is reduced. Therefore, the upper limit of the addition amount is 15% by weight, and there is a problem that the weight cannot be sufficiently reduced.

[0004] In view of the above problems, an object of the present invention is to provide a lightweight inorganic molded article having high strength and excellent surface properties, and a method for producing the same.

[0005]

According to the present invention, there is provided a lightweight inorganic molded article comprising a cement 20 to 20 to achieve the above object.
60% by weight, 5 to 25% by weight of a wood fiber having an average fiber length of 1.5 to 8 mm and an average fiber width of 0.2 to 0.9 mm, and an inorganic foam 18 containing amorphous silica as a main component. 60 wt%. Further, it is preferable that the inorganic foam has a bulk density of 0.5 or less after applying a water pressure of 5 Mpa and a volume compressibility of 70% or less before and after the application of the water pressure.

In order to achieve the above object, a method for producing a lightweight inorganic molded article according to the present invention comprises dry-mixing cement, an inorganic foam mainly composed of amorphous silica, and wood fiber. A mixture obtained by uniformly mixing the inorganic foam and the cement between the wood fibers is obtained. After adding 40 to 80% by weight of water to the mixture and further mixing, the mixture is deposited in a mat shape and press-molded. Then, the cement is hydrated and hardened by primary curing, and autoclaved for 2 hours.
The method comprises a step of causing the calcium of the cement to react with the amorphous silica of the inorganic foam to form a calcium silicate compound and to develop the strength.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A lightweight inorganic molded article according to the present invention has a cement of 20 to 60% by weight and an average fiber length of 1.5.
5 to 25% by weight of wood fibers having an average fiber width of 0.2 to 0.9 mm and an inorganic foam having amorphous silica as a main component of 18 to 60% by weight. is there.

The cement is used as a binder for wood fibers and inorganic foams. Examples of the cement include ordinary portland cement, early-strength cement, alumina cement, magnesia cement and the like. It is suitable. When the addition amount is less than 20% by weight,
If the strength of the molded article cannot be maintained and exceeds 60% by weight, the amount of wood fiber or inorganic foam added becomes relatively low, and a desired lightweight inorganic molded article cannot be obtained.

The wood fiber is added to increase the strength of the brittle inorganic molded body, and the amount of the wood fiber is 5 to 5.
Preferably it is 25% by weight. If the addition amount is less than 5% by weight, the reinforcing effect is insufficient, and if it exceeds 25% by weight, there is a problem in terms of fire protection.

In the present invention, since the bulking effect can be secured by adding a large amount of the inorganic foam, there is no need to increase the bulk with wood fibers. Therefore, as the wood fiber, a short and thin fiber bundle having an average fiber length of 1.5 to 8 mm and an average fiber width of 0.2 to 0.9 mm (a relatively small amount of single fiber bundle)
Can be used. As a result, the surface of the molded body becomes smoother than when a long and thick wood fiber bundle is used, and when the embossing is performed, the fibers easily follow the molding die, so that sharp irregularities are obtained. There are advantages. The aspect ratio (fiber length / fiber diameter) is preferably in the range of 5 to 20 in order to enhance the reinforcing effect and obtain an inorganic molded body having excellent surface properties and embossability.

The inorganic foam is used for reducing the weight of the inorganic molded article and improving the surface properties, and examples thereof include pearlite, obsidian foam, and shirasu foam. In the prior art, a crystalline silica component such as silica stone or silica sand was added, and the mixture was cured in an autoclave, thereby performing a silica reaction with the cement. In contrast, the inorganic foam of the present invention contains amorphous silica as a main component and itself reacts with cement, so that it is not necessary to separately add a silica component. In addition, since the amorphous silica of the above-mentioned inorganic molded body has higher reactivity and a larger surface area than crystalline silica, it easily reacts to generate a calcium silicate compound, and an inorganic molded body having a desired strength is developed. can get.

It is preferable that the amount of the inorganic foam to be added is 18 to 60% by weight. If the addition amount is less than 18% by weight, the weight cannot be reduced sufficiently, and the wood fibers cannot be sufficiently dispersed when mixed, so that the wood fibers are lump. Further, the inorganic foam is not sufficiently filled between the wood fibers, so that a rough portion is formed and the surface property is deteriorated. On the other hand, if the added amount exceeds 60% by weight, the added amount of cement or wood fiber becomes relatively low, and the desired strength cannot be obtained. In addition, 18 ~
In the range of 60% by weight, as the amount of the foam added increases, the filling property increases, and the surface property improves. When the addition amount is small, for example, the addition amount is 30% by weight.
Even in the case where the amount is smaller than the degree, by adding the inorganic foam having a small particle diameter, the filling property is enhanced and the surface property is improved.

Conventionally, when water is added and mixed, wood fibers may absorb excess water and become lump. Even if a large amount of wood fibers is added to the inorganic molded body, a sufficient reinforcing effect is exhibited. Did not. On the other hand, if the amount of added water is reduced so that the wood fiber does not become lump, the water required for hydration and hardening of the cement becomes insufficient, and the strength of the cement may not be sufficiently exhibited. In the present invention, by adding a large amount of inorganic foam, a part of water necessary for hydration and hardening of cement is absorbed by the inorganic foam. For this reason, even if a large amount of water is added, it is possible to prevent wood fibers from being littered, to secure water necessary for hydration and hardening of cement, and to obtain an inorganic molded body having sufficient strength.

The inorganic foam has an average particle size of 50 to 300 μm, a bulk density under a water pressure of 5 MPa, of 0.5 or less, and a volume compressibility of about 7 or less before and after the water pressure.
It is preferable to use one having 0% or less. If the average particle size of the inorganic foam is less than 50 μm, the thickness of the shell of the foam becomes larger than the particle size, so that the bulk density increases and the weight increases. Also, if the average particle size exceeds 300 μm, the thickness of the shell of the foam becomes thin and the foam easily breaks.

The reason why the bulk density when compressed by applying a water pressure of 5 MPa is 0.5 or less is that if the bulk density exceeds 0.5, even if added, it does not contribute to weight reduction. The reason why the reference pressure is set to 5 Mpa is that the pressure is substantially equal to the pressure at the time of press-molding the molded body, and the inorganic foam is not broken by the pressure at the time of press-molding. Therefore, according to the present invention, the inorganic foam is not destroyed even during press molding, and a smooth and sharp embossed surface can be obtained while maintaining a light weight. The reason why the volume compression ratio is set to 70% or less is that if the volume compression ratio exceeds 70%, many of the materials are destroyed by pressure, the bending strength is reduced, and the broken inorganic foam is used to drive nails. This is because the impact force at the time cannot be reduced, and cracks are likely to occur in the nailed portion.

The method of measuring the bulk density and volume compressibility of these inorganic foams is performed as follows. When measuring the bulk density of an inorganic foam, 100
After placing in a cc stainless steel container and tapping up and down 180 times, the bulk density is measured with a powder tester (manufactured by Hosokawa Micron), which is a dedicated measuring device. next,
The foam whose bulk density has been measured is placed in a plastic bag or the like, and the air in the bag is evacuated with a vacuum pump. Then, the bag is placed in a pressurized tank filled with 3 liters of water, and pressurized with a hydrostatic pump at a hydrostatic pressure of 5 MPa for 60 seconds. Then, the inorganic foam is taken out of the bag, and the bulk density is measured by tapping in the same manner as described above, and the volume compression ratio is calculated from the bulk density before and after pressurization.

If necessary, a curing accelerator 1 such as aluminum chloride, magnesium chloride, calcium chloride, etc.
5% by weight may be added.

A method for producing a lightweight inorganic molded article according to the present invention will be described. First, cement, an inorganic foam mainly composed of amorphous silica, and wood fibers are dry-mixed to obtain a mixture in which the inorganic foam and cement are uniformly mixed between the wood fibers. Then add 4 parts of water to this mixture.
Add 0-80% by weight and mix further. Then, the obtained mixture was deposited in a mat shape and press-molded.
Next cure and cure. Further, secondary curing is carried out in an autoclave, and calcium of the cement is reacted with amorphous silica of the inorganic foam to produce a calcium silicate compound, thereby obtaining a lightweight inorganic molded article exhibiting strength.

Since the cement, the inorganic foam mainly composed of amorphous silica, and the wood fiber are put into a mixer and mixed in a dry system, the mixture obtained by uniformly mixing the inorganic foam and the cement between the wood fibers is obtained. can get.

Further, water 4 is added to the uniformly mixed mixture.
Since 0 to 80% by weight is added and mixed, water is not adsorbed excessively only to the wood fibers, but is also adsorbed uniformly to the inorganic foam and the gaps therebetween. For this reason, the wood fiber does not lump, and a mixture in which the wood fiber, the inorganic foam and the cement are uniformly mixed is obtained.

The amount of water to be added to the mixture is from 40 to
The reason for setting the content to 80% by weight is that if the addition amount is less than 40% by weight, the water content with respect to the cement becomes too small, and the predetermined strength cannot be obtained. On the other hand, if it exceeds 80% by weight, the water content becomes excessive and the wood fiber is liable to be lumped, and the water absorption of the molded article after the cement is hardened increases. The amount of water added is required to be 25% by weight as an amount required for hydration of cement, and it is preferable to add approximately the same weight of water to wood fibers and lightweight aggregates.

Conventionally, the amount of water to be added was appropriately determined based on experience and intuition, so that the strength was likely to vary due to excess or deficiency of water. However, by adding an appropriate amount of water, the strength was reduced. An inorganic molded body without variation can be obtained. Conventionally, when a large amount of inorganic foam is not added, the wood fiber absorbs a large amount of water, so that the wood fiber is liable to be deceived. On the other hand, if the addition amount is reduced in order to prevent the wood fiber from being trapped, there is a problem that water required for hydration hardening of the cement cannot be supplied, and the strength often decreases. According to the present invention, the above-mentioned problems can be solved.

The mixture was sprayed on a plate to a thickness of 5
After being deposited in a mat shape of 0 to 100 mm, an embossed plate is placed on the upper surface, molded by a press machine, primary cured as it is, and cured to a handleable strength. The primary curing is preferably performed at a temperature of 50 to 80 ° C. for 10 hours or more.

The secondary curing performed in an autoclave after removing the embossed plate is carried out by reacting calcium of cement with amorphous silica of inorganic foam to obtain CHS (I),
This is a step for producing a calcium silicate compound such as CHS (II) and obtaining a final lightweight inorganic molded article exhibiting practical strength. After the cement is hydrated and hardened in the primary curing and then secondary cured in the autoclave, the calcium of the cement reacts with the amorphous silica of the inorganic foam having a large surface area to produce a calcium silicate compound. Thus, a lightweight inorganic molded article having the following strength can be obtained. The secondary curing by the autoclave is preferably performed at a temperature of 130 to 180 ° C. for 5 to 15 hours, particularly at 165 ° C. for 6 hours.

According to the present invention, a high-strength compact having a light weight and uniform distribution of fibers can be obtained. For this reason, it is not necessary to form a molded article having a multilayer structure in which a low-density core layer is sandwiched between high-density high-strength front and back layers as in the related art. . However, in the present invention, it goes without saying that the composition ratio of the front and back layers and the core layer may be changed to form a three-layer structure.

[0026]

(Example 1) Ingredients shown in Fig. 1 were blended with raw materials, in particular, shirasu foam as an inorganic foam, cedar with an average fiber of 5.5 mm as a wood fiber, and magnesium chloride as a hardening accelerator. After mixing with a mixer for 2 minutes, a predetermined amount of water was added, and the mixture was further mixed for 30 seconds to obtain a mixture. The mixture was sprayed on a stainless steel plate and deposited in a 70 mm-thick mat shape, and then a resin emboss plate was placed on the upper surface and sandwiched, and a plurality of mats in this state were stacked. Then, it is pressurized at a pressure of about 5 Mpa and clamped as it is.
The mat was cured under primary conditions under the conditions of time, and the mat was hardened until a sufficient strength to be handled was obtained. Then, after removing the plate, secondary curing was performed in an autoclave at a temperature of 165 ° C. for 6 hours to obtain a final inorganic molded body. A sample was cut out from the obtained molded body, and various measurements such as specific gravity, nailing property, bending strength, and peel strength were performed. Figure 1 shows the measurement results
Shown in

Examples 2 to 14 and Comparative Examples 1 to 5 Examples 2 to 14 and Comparative Examples 1 to 5 also correspond to FIGS.
The raw materials were blended at the composition ratio shown in Example 3, and an inorganic molded article was obtained in the same manner as in Example 1, and the physical properties were measured. The measurement results are shown in FIGS.

The method for measuring physical properties and the method for measuring fiber length are as follows. Surface properties: The final molded product is visually observed. ◎: There is almost no coarse part, ：: There is a little coarse part, Δ: The coarse part is conspicuous, ×: The coarse part is very conspicuous. Mixability: The mixed state of the raw materials after adding water is visually observed. ◎: No deficiency, ○: Slight deficiency, Δ: Defective, ×: Many deficiency Nailability: The condition when a nail having a length of 45 mm and a diameter of 2.4 mm was driven into the embossed portion of the sample. Observe visually. ：: almost no chipping, ○: chipping but not noticeable, Δ: chipping and noticeable, ×: almost chipping Bending strength: Performed according to JIS-A-1408. Peel strength: A metal tensile jig is adhered to both sides of a 50 × 50 mm sample with an epoxy adhesive, and the peel strength is measured with a tensile tester. Fiber length: Fibertron (manufactured by Microtec) was used. The principle of measurement using a fibertron was that a fiber dispersed in water was photographed with a video camera, image processing was performed to measure the length of the fiber, and then analyzed by a computer to calculate the average fiber length. According to this method, the fiber lengths of all the sampled materials can be measured.

FIG. 1 shows comparison data of the physical properties of Examples 1 to 6 and Comparative Example 1 when the amount of the lightweight aggregate was changed. Example 1 wherein the amount of the inorganic foam added was 18 to 60% by weight.
6 were found to be superior to Comparative Example 1 in which the added amount was 15% by weight in each of the physical property values.

Particularly, when the amount of the inorganic foam added is 40% by weight.
In the above Examples 4, 5, and 6, it was found that the filling property of the inorganic foam was enhanced, the surface properties were extremely improved, and the strength was also improved.

FIG. 2 shows physical property comparison data of Examples 7 to 10 and Comparative Examples 2 and 3 when the length of the wood fiber was changed. From the measurement results of Examples 7 to 10 in which the length of the wood fiber was in the range of 1.5 to 8 mm, it was found that the longer the wood fiber was, the stronger and the shorter the wood fiber was, the better the surface properties were. On the other hand, in the case of Comparative Example 3 in which the length of the wood fiber was as long as 10 mm, the desired strength could be secured, but the roughness of the surface was conspicuous. In the case of Comparative Example 2 in which the length of the wood fiber was 0.8 mm, an inorganic molded body having a measurable strength was not obtained, and its physical properties could not be measured.

FIG. 3 shows physical property comparison data obtained when inorganic foams having different bulk densities after applying a water pressure of 5 Mpa and different volume compressivities before and after the water pressure are used. Example 11
In Comparative Example 4 in which the bulk density of the inorganic foam after application of water pressure exceeded 0.5, the desired strength was not exhibited and the nailing property was poor, as compared with Comparative Examples Nos. This is considered to be because a sufficient bulk was not obtained at the time of press molding, and the foam, cement, and wood fiber did not sufficiently adhere inside the molded body. In Comparative Example 5 in which the volumetric compression ratio before and after the application of water pressure exceeded 70%, there were many nailing chips.
This is considered to be because many aggregates were broken by water pressure and there were few voids in the sample.

[0033]

According to the lightweight inorganic molded article of the first aspect, a desired bulking effect can be ensured by adding a large amount of an inorganic foam mainly composed of amorphous silica having good reactivity. Thus, a lightweight inorganic molded article can be obtained. Furthermore, compared with the conventional example, since thin and short wood fibers are added, a lightweight inorganic molded article having a smooth surface and sharp embossability can be obtained.

According to the second aspect, since the inorganic foam having a predetermined bulk density and volume compressibility is added, the inorganic foam is not broken even by press molding. For this reason, while maintaining the weight reduction, it is possible to obtain an inorganic molded body in which the bending strength does not decrease and cracking due to nailing does not easily occur.

According to the third aspect, after the cement, the inorganic foam mainly composed of amorphous silica, and the essential components of the wood fiber are dry-mixed, a predetermined amount of water is added to the mixture. Mix further. For this reason, not only can it be uniformly mixed, but also there is an effect that an inorganic molded article having a desired strength can be obtained by hydration hardening of the cement and reaction with the inorganic foam.

[Brief description of the drawings]

FIG. 1 is a table showing an example of a lightweight inorganic molded article according to the present invention.

FIG. 2 is a table showing another example of the lightweight inorganic molded article according to the present invention.

FIG. 3 is a table showing another example of the lightweight inorganic molded article according to the present invention.

Continuing on the front page (72) Inventor Kazuhiro Sato 1-in-1 Inami-cho, Inami-cho, Higashi-Tonami-gun, Toyama Prefecture (72) Inventor Hirofumi Nonaka 1-in-1 Inami, Inami-cho, Higashi Tonami-gun, Toyama Prefecture Within Industrial Co., Ltd. (72) Inventor Masayuki Oshima 1-in-1 Inami-cho, Inami-cho, Higashi-Tonami-gun, Toyama Prefecture Inside (72) Inventor Tsuyoshi Toda 1-large, Inaba-cho, Inami-cho, Higashi Tonami-gun, Toyama 4G012 PA04 PA07 PA22 PB09 PC04 PC11 PC12

Claims (3)

[Claims] 1. A cement comprising 20 to 60% by weight of cement, 5 to 25% by weight of wood fiber having an average fiber length of 1.5 to 8 mm, average fiber width of 0.2 to 0.9 mm, and amorphous silica. A lightweight inorganic molded article comprising 18 to 60% by weight of an inorganic foam as a component. 2. The inorganic foam according to claim 1, wherein the bulk density after applying a water pressure of 5 Mpa is 0.5 or less, and the volume compressibility before and after the application of the water pressure is 70% or less. The lightweight inorganic molded article according to claim 1. 3. A mixture obtained by dry-mixing cement, an inorganic foam mainly composed of amorphous silica, and wood fiber, and uniformly mixing the inorganic foam and cement between the wood fibers. After adding 40 to 80% by weight of water to the mixture and further mixing the mixture, the mixture is deposited in a mat form and press-molded, then primary cured to hydrate and harden the cement, and secondary cured in an autoclave. To react the calcium of the cement with the amorphous silica of the inorganic foam,
A method for producing a lightweight inorganic molded article, comprising producing a calcium silicate compound to develop strength.