JP2646278B2 - Manufacturing method of inorganic cured molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an inorganic cured hollow molded article, and particularly to a molded article such as a cement type, a calcium silicate type, a gypsum slag type, etc., which has a wide application as a building material. The present invention relates to a method of manufacturing by extrusion.

[Conventional technology]

In the case of inorganic hardened molded products, those made using only inorganic hydraulic materials such as cement alone or those obtained by mixing aggregates with them have low strength and are easily cracked. From the above molded products, it has become popular to mix asbestos for the purpose of increasing the strength of the product, reducing the weight, improving the weather resistance, etc., and asbestos-cement extruded plates have been mass-produced as a representative example. Carcinogenicity of asbestos has been pointed out, and its use has been problematic from an environmental health point of view.

Instead, other fibers, for example, steel fibers, metal fibers such as amorphous metal fibers, inorganic fibers such as glass fibers, carbon fibers, ore wool, polypropylene fibers, polyamide fibers, polyvinyl alcohol fibers, polyacryl fibers, etc. It has been proposed to use organic fibers alone or in combination, and some of them have been put to practical use. In addition, use of wood flour or plant fiber has been proposed to ensure the moldability during extrusion molding or the shape retention of raw products.

However, steel fibers have problems such as coloring due to the generation of rust and a drop in strength.Amorphous metal fibers are expensive and therefore impractical. Glass fibers and ore wool are eroded by alkali attack of cement. However, there is a problem in durability, and carbon fibers have low dispersibility and low adhesion to cement, and are expensive. Organic fibers have insufficient heat resistance, impair the incombustibility of products, and are easily hydrolyzed under hydrothermal conditions.
Autoclave curing at temperatures above 160 ° C is not possible.

On the other hand, vegetable fibers have a hygroscopic property, the size of the fibers changes with the water content, and when immersed in water for a long time, the fibers swell and also cannot withstand heat of about 100 to 120 ° C or more. There is a drawback ("Fibre Concrete", page 162 by DJ Hannant), and the extruded plate obtained has a large dimensional change rate due to water absorption, and when used as an exterior material, cracks occur due to repeated water absorption and drying. Easy and durable. In addition, since the plant fibers are flammable, the noncombustibility of the obtained extruded plate is impaired.

[Problems to be solved by the invention]

The present invention aims to eliminate the disadvantages caused by various reinforcing fibers as described above, and uses a plant fiber which is inexpensive and easy to secure the formability as a raw material, eliminates dimensional change due to water, and has strength. By improving the adhesiveness of cement, etc., and modifying it to give flame retardancy, and using it as a reinforcing fiber, it improves strength, processability, weight reduction, etc., as well as moldability and The purpose is to extrude an inorganic cured hollow molded product having the same formability and shape retention as in asbestos-based products by securing the shape retention properties as well as by using asbestos products, and to obtain it by autoclaving. It is.

[Means for solving the problem]

The present invention relates to a molding material containing an inorganic hydraulic material, wherein a modified plant fiber in which a water-insoluble inorganic compound is fixed from the aqueous solution of a water-soluble inorganic compound to the inside and the surface of the plant fiber is added in an amount of 0.5 to 15% by weight of the whole formulation. The object was achieved by a method for producing an inorganic cured hollow molded article, which was characterized by adding water, kneading, extruding and autoclaving.

The inorganic hydraulic material used in the present invention is an inorganic material that is hardened by water, such as various cements such as Portland cement, blast furnace cement, and fly ash cement, calcium silicates, gypsum, and slag gypsum. Any of those known as hard materials can be used.

The modified vegetable fiber used in the present invention is one obtained by fixing an insoluble inorganic compound to the inside and the surface of a vegetable fiber from a water-soluble inorganic compound aqueous solution. The fixing amount of the insoluble inorganic compound is preferably 10 parts by weight or more based on 100 parts by weight of the bone-dry plant fiber. Although the durability increases as the amount of fixation increases, advantages such as processability and weight reduction may decrease. Therefore, it is preferable that the amount is not more than 200 parts by weight based on 100 parts by weight of the absolutely dried plant fiber. When the fixing amount is 10 parts by weight or less, the durability is reduced.

As the plant fiber used for the modified plant fiber, any known plant fiber is used, and cotton, hemp, pulp, and the like are preferably used. However, it is not necessary that the plant fiber be in a completely separated fiber state. It can also be used in the form of wood chips.

Any water-insoluble inorganic compound used in the present invention can be used as long as it is substantially insoluble in water, and the type thereof is not particularly limited, but the following types can be used.

Metal phosphate: Ba ₃ (PO ₄ ) ₂ , CaHPO ₄ , Al (H ₂ PO ₄ ) ₃ metal hydroxide: Ca (OH) ₂ , Al (OH) ₃ , Fe (OH) ₂ metal carbonate: CaCO ₃ , Al ₂ (CO ₃ ) ₃ Metal borate: BaHBO ₃ Metal sulfate: CaSO ₄ , BaSO ₄ Apatite: M ₁₀ (ZO ₄ ) ₆ X ₂ M: 1 to 3 trivalent ions, Ca, Pb, Cd , Sr, Ni, Al, Na, K, Ba, etc. Z: 3- to 7-valent ions, P, Al, As, Cr, Si, C, S, etc. X: 0 to 3-valent ions, OH, F, Cl, Br , I, O, CO ₃ , H ₂ O etc.Ettringite: 3CaO ・ Al ₂ O ₃・ 3CaSO ₄・ nH _{2 On} n = 28〜32 Inorganic ultrafine particles: SiO ₂ , CaCO ₃ , Al ₂ O ₃ , TiO ₂ etc (Particle size 0.1 μm or less) Among them, CaHPO ₄ , Al (OH) ₃ , CaCO ₃ , apatite,
Ettringite, silicon dioxide and the like are preferably used.

Further, as a method of fixing the water-insoluble inorganic compound to the inside and the surface of the plant fiber, any method other than the method exemplified below may be used.

(1) A method in which a plant fiber is sequentially impregnated with a plurality of aqueous solutions of an inorganic compound that produce an insoluble inorganic compound by mixing, and ions contained in each aqueous solution are reacted with each other to generate an insoluble inorganic compound.

(2) A method of impregnating plant fibers with an aqueous solution of a compound that reacts with carbon dioxide to produce a water-insoluble inorganic compound, and then placing the impregnated plant fibers in a carbon dioxide atmosphere.

 Examples of fixing by such a reaction will be described below.

Boric acid metal salt BaCl ₂・ 2H ₂ O ＋ H ₃ BO ₃ → BaHBO ₃ For the impregnation of the aqueous solution of the inorganic compound into the plant fiber or the subsequent generation of the water-insoluble inorganic compound, it can be used depending on additives such as various surfactants and flocculants.

The modified plant fiber in which the water-insoluble inorganic compound is fixed inside and on the surface of the plant fiber is blended with a molding material containing an inorganic hydraulic material in an amount of 0.5 to 15% by weight of the whole formulation. During the compounding, as a molding material, various reinforcing fibers other than the above-mentioned modified plant fibers, various aggregates, fillers, AE agents, water reducing agents,
Additives such as dispersants can be included as needed.

The compound formulated as described above has good properties such as shape retention properties even when water is added, and a kneaded material suitable for extrusion molding is obtained and hardens with the passage of time. The mixture obtained by kneading and kneading is extrusion-molded to obtain a desired molded body, which is subjected to autoclave curing and curing to produce a desired inorganic cured hollow molded article.

By the above-mentioned extrusion molding, various hollow shaped articles can be obtained.For example, plate-shaped, columnar, pipe-shaped, hollow shaped articles of other shapes can be obtained.
Since hollow wall materials, roof materials, pillars, floor materials, various pipes, and the like can be made, they can be applied to a wide range of fields such as construction and civil engineering.

In curing the hollow molded body obtained by the molding, curing is performed, and the curing method is characterized by autoclave curing.

In particular, when organic fibers are used as the reinforcing fibers, autoclave curing cannot be performed at a temperature of 160 ° C. or higher as described above, but the hollow molded body obtained by the extrusion molding of the present invention includes modified plant fibers. 160 to use
Since the autoclave curing at a temperature of not less than ℃ can be performed, there is an advantage that the maximum strength can be reached in a short time by the curing means.

[Action]

Conventionally, ordinary reinforcing fibers other than asbestos or vegetable fibers, plasticizers, and the like are blended with an inorganic hydraulic material, and water is added and kneaded to extrude, and then the raw seed after kneading (refers to "kneaded material") Is poor in water retention and fluidity, and solids such as cement and water are separated and dehydrated in the extruder or in the mouthpiece, so that they are hardly clogged and cannot be extruded. By increasing the amount of water, the flowability of the raw seeds is improved, and it is possible to temporarily extrude the raw material outside the die. However, the shape retention of the raw product immediately after extrusion is poor, and a so-called "sagging" phenomenon occurs. Therefore, the range of the amount of water that can be extruded with hardness that can maintain the shape of the molded product is extremely narrow,
In actual operation, it is difficult to determine the amount of water.

However, when vegetable fibers are added as a reinforcing fiber, the above-mentioned drawbacks are improved, and the formability such as water retention and flowability of raw seeds and the shape retention of raw products are improved. Fibers change in fiber size with moisture content,
The fiber swells when soaked in water for a long time, and is a material with poor heat resistance and fire resistance.In addition, since its elastic modulus is low, it is not very useful for improving the strength of high specific gravity products. Extruded products using vegetable fibers instead often have inferior quality compared to asbestos products.

In the present invention, a modified plant fiber obtained by fixing a water-insoluble inorganic compound from the aqueous solution of a water-soluble inorganic compound to the inside and the surface of the plant fiber has improved water resistance due to the bulking effect of the plant fiber and reduced dimensional change due to water absorption. The dimensional change rate and weather resistance of the obtained product are not impaired. The modified vegetable fiber has a water-insoluble inorganic compound fixed on its surface, so that the affinity with the inorganic hydraulic material is increased, and during kneading, mixing and dispersion are sufficiently performed to improve the shape retention property and the like. Contribute to improvement. And since it also has the property of vegetable fiber, it does not lose the property of good water retention, and has good molding characteristics such as fluidity and water retention. In addition, it is possible to improve the bending strength of the hollow molded article, probably because the elastic modulus of the modified vegetable fiber is increased. Furthermore, since the heat resistance and fire resistance of the fiber itself are also improved, the heat resistance and fire resistance of the obtained hollow molded article are improved. Since the modified plant fiber is less likely to be degraded by autoclaving like ordinary plant fiber, autoclaving is employed for curing the hollow molded article when it is cured.

When the fixed amount of the water-insoluble inorganic compound is less than 10 parts by weight per 100 parts by weight of the plant fiber (absolutely dried), the modified plant fiber is not sufficiently modified, and the dimensional change of the obtained molded article is not improved. In some cases, the amount of fixation is preferably 10 parts by weight or more.

In the present invention, the modified plant fiber is added to the molding material containing the inorganic hydraulic material in an amount of 0.5 to 15% by weight of the entire composition.
This is at least 0% to improve the raw molding performance.
5 wt% is required, and even if it is 15 wt% or more, there is improvement, but if it exceeds 15 wt%, the nonflammability of the product is impaired and its use as a building material is limited, so the upper limit is 15 wt%.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

Examples 1-2 LBKP (hardwood bleached kraft pulp) with a pulp concentration of 3%
After that, wet pulp having a water content of about 300% was obtained with a compression molding machine. This was immersed in a 1.5 mol / barium chloride aqueous solution for 15 minutes. Next, after removing excess barium chloride with a compression molding machine, the barium chloride was immersed in a 3.5 mol / aqueous ammonium hydrogen phosphate solution for 20 minutes. After washing and drying, the rate of weight increase was measured.
was gotten.

After the improved plant fiber A is dissociated with a crusher, it is kneaded with the composition shown in Table 1, and the extruder is used to form a hollow shape having a width of 500 mm and a thickness of 50 mm. After molding the molded article of the above), the molded article was subjected to a predetermined autoclave curing to obtain an extruded hollow molded plate.

Comparative Examples 1-4 Extruded hollow molded plates were obtained in the same manner as in Examples 1-2, except that the compositions in Table 1 were followed.

Example 3 Except that LBKP was replaced with wood flour (diameter 3 mm or less), the same procedure as in Examples 1 and 2 was carried out.
% Modified plant fiber B was obtained.

Examples 1 and 2 except that the modified vegetable fiber B was used
After molding in the same manner as described above, autoclaving was performed at 180 ° C. for 10 hours to obtain an extruded hollow molded plate.

Example 4 Except that the concentration of barium chloride aqueous solution was set to 1 mol / and the concentration of ammonium hydrogen phosphate aqueous solution was set to 1.5 mol /, treatment was performed in the same manner as in Examples 1 and 2 above.
13% of modified vegetable fiber C was obtained.

Except that this modified vegetable fiber C was used, an extruded hollow molded plate was obtained in the same manner as in Example 3 above.

Comparative Example 5 Except for using LBKP pulp instead of modified plant fiber,
Extruded hollow molded plates were obtained in the same manner as in Example 3 above.

For Examples 1 to 4 and Comparative Examples 1 to 5, the bending strength, dimensional change rate, and bulk specific gravity of the hollow molded article were measured. The dimensional change rate was determined by measuring the dimensional change when the molded article was allowed to absorb water for 48 hours to make it saturated, and when the molded article was completely dried. Crack test is 10 cycles of “wet (24 hours immersion in water)-dry (90 ° C, 24 hours dry)”
After repeating this process, the surface of the extruded hollow molded plate and the presence or absence of cracks at the edge were visually observed. The measured result is the first
The results are shown in Table 2 and Table 2.

[Effects of the Invention] According to the present invention, a water-insoluble inorganic compound is mixed with a modified plant fiber fixed to the inside and surface of the plant fiber from a water-soluble inorganic compound aqueous solution. In addition, the kneaded product is rich in moldability and shape retention in addition to water retention, so that a hollow molded body can be easily obtained by extrusion molding, and the range of moisture content suitable for extrusion molding is wide. The modified vegetable fiber has a high affinity for inorganic hydraulic materials and the like, and its mixing and dispersion are well performed in kneading.

Further, since the modified vegetable fiber has improved water resistance and the like, the inorganic molded hollow molded article obtained by autoclaving and curing the above-mentioned hollow molded article has a small dimensional change rate and is hard to crack. Durability, weather resistance, and high bending strength. Further, since this molded product has sufficient heat resistance and fire resistance, it can be used as a building material.

Autoclaving can be performed for curing of the hollow molded body obtained by the extrusion molding during curing, so that the maximum strength can be reached in a short time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 14/46 C04B 14/46 24/38 24/38 A

Claims (1)

(57) [Claims] A modified plant fiber obtained by fixing a water-insoluble inorganic compound from the aqueous solution of a water-soluble inorganic compound to the inside and surface of a plant fiber is added to a molding material containing an inorganic hydraulic material in an amount of 0.5 to 15% by weight of the whole formulation. A method for producing an inorganic cured hollow molded article, comprising mixing, adding water, kneading, extruding, and autoclaving.