JPH04254460A - Water hardening inorganic molded body and its manufacture - Google Patents

Abstract

PURPOSE:To solve such a problem that an acrylic fiber does not show enough reinforcing effect under autoclave aging conditions, and to offer a water hardening inorg. molded product and method for producing this product showing high strength and excellent dimensional stability by extrusion molding. CONSTITUTION:An acrylic fiber and a water hardening material essentially comprising cement and amorphous silicate are mixed, and extrusion molded and aged in an autoclave. This water hardening inorg. molded body features in the specific bending strength higher than 80kg/cm<2> obtd. by calculating the ratio of the bending strength to the square of the specific gravity. This product is produced by mixing an cement, amorphous silicate of >=1mum average particle size, and amorphous silicate of <1mum average particle size by 0-30wt.%, and acrylic fiber, kneading with water and extrusion molding and aging in an autoclave.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic inorganic molded product having high strength and excellent dimensional stability, suitable as a building member, and a method for producing the same.

0002

[Prior Art] Conventionally, inorganic molded articles for construction, such as asbestos cement boards, calcium silicate boards, lightweight aerated concrete boards (ALC), etc., have been made using hydraulic inorganic materials consisting of calcareous materials and silicic materials under high-temperature steam. When cured in an autoclave, a highly crystalline hydrate called tobermorite is formed. Roofing materials, flooring materials, exterior walls, partition materials, etc. made of such highly crystalline hydraulic inorganic materials have high strength, excellent insulation properties and thermal stability, and are also resistant to drying shrinkage. It is said that it is possible to increase chemical resistance by reducing the amount of carbon dioxide. Therefore, as reinforcing fibers for the above-mentioned high-performance hydraulic inorganic molded products that require curing in such high-temperature steam,
Asbestos and reinforcing steel, which can withstand high-temperature alkalis, have been used. However, asbestos is a natural material, and as most of it is imported, its price fluctuates widely, and in recent years it has become clear that asbestos is harmful to health and hygiene. Its use is being avoided or restricted.

[0003] Therefore, attempts have been made to use acrylic fibers with excellent alkali resistance in place of asbestos. For example, Japanese Patent Application Laid-Open No. 61-6159 describes a method in which a slurry-like mixture consisting of a hydraulic material whose main raw materials are silicic acid and calcareous material and acrylic fiber is formed by a papermaking method and then cured in high-temperature steam. Unexamined Japanese Patent Publication 1986-1973
42 describes a method of steam curing at a temperature of 110 to 160°C using high-strength, high-modulus acrylic fibers with an intrinsic viscosity of 2.5 or more, and JP-A-63-282144 discloses a method of curing with steam at a temperature of 110 to 160°C. A method using copolymerized high-strength, high-modulus acrylic fibers and curing in steam at 110°C or higher, and JP-A-2-129053 disclose a method using high-strength acrylic fibers with a weight average molecular weight of 400,000 or higher.
Inventions related to cement products cured at 80°C have been disclosed.

By the way, in recent years, as a method for obtaining high-strength hydraulic inorganic molded articles, a method of extruding a hydraulic material made of calcareous material, silicic acid, etc. and then curing it in an autoclave has been attracting attention. For example, JP-A-64-18953
The publication contains ultrafine powder without pozzolanic properties, and contains water/
Inventions related to extrusion molding compositions having a solids ratio of 20 to 40% by weight, or extrusion molding compositions containing ultrafine crystalline silica stone are disclosed in JP-A-1-93446.

However, even with these proposed methods, it is difficult to obtain a high-strength hydraulic inorganic molded product because the acrylic fiber does not exhibit sufficient reinforcing effect under steam curing at a high temperature of 180°C, that is, under autoclave curing. It has not been done.

[0006]

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problem that acrylic fibers do not exhibit a sufficient reinforcing effect under autoclave curing, and to provide high strength and dimensional stability in extrusion molding. To provide a hydraulic inorganic molded article with excellent properties and a method for producing the same.

[0007]

[Means for Solving the Problems] The object of the present invention is to extrude a mixture of cement and a hydraulic substance whose main raw materials are amorphous silicic acid, and acrylic fibers, and then cure the mixture in an autoclave. This can be achieved by making a hydraulic inorganic molded product characterized by exhibiting a specific bending strength of 80 kg/cm 2 or more, which is obtained by dividing the bending strength by the square of the specific gravity.

[0008] Furthermore, the method for producing a hydraulic inorganic molded article of the present invention includes cement, an amorphous silicic acid material having a weight average particle size of 1 μ or more, and an amorphous silicic acid material having a weight average particle size of less than 1 μm.
A method for producing a hydraulic inorganic molded article, which is characterized in that a mixture of a hydraulic substance and acrylic fibers containing 30% by weight as a main raw material is kneaded with water, extrusion molded, and then subjected to autoclave curing.

[0009]

[Operation] The present invention will be explained in more detail below.

[0010] In order to produce hydraulic inorganic molded products with high strength and excellent dimensional stability as building materials, calcareous (Ca)
It is necessary to convert a hydraulic material containing approximately equal moles of O) and silicic acid (SiO2) into a highly crystalline hydrate in an autoclave under high-temperature steam. In order to sufficiently exhibit the reinforcing effect of acrylic fibers in such hydraulic inorganic molded articles, firstly, the molding method is important, and secondly, the type, particle size, and amount of the silicic acid compound are important.

In the present invention, cement is used as the calcareous material among the hydraulic materials. Examples of cement include single cement such as Portland cement and alumina cement, and mixed cement such as blast furnace cement. On the other hand, as the silicic acid, an amorphous silicic acid having a weight average particle size of 1 μm or more and an amorphous silicic acid having a weight average particle size (hereinafter simply referred to as "particle size") of less than 1 μm are used. Examples of the amorphous silicic acid having a particle size of 1 μm or more include fly ash and blast furnace slag, and examples of the amorphous silicic acid having a particle size of less than 1 μm include silica fume, diatomaceous earth, and clay. Among these, a combination of fly ash and silica fume is most preferably used. Here, the amount of amorphous silicic acid with a particle size of less than 1μ is 0 to 30% by weight, preferably 1 to 25% by weight.
% by weight, more preferably 3-20% by weight. If the blending amount exceeds 30% by weight, the silicic acid substance will aggregate, and as will be described later, the fluidity will decrease even when the amount of water added is small, making extrusion molding difficult. Therefore, the reinforcing effect of the acrylic fibers is significantly reduced.

By the way, the above-mentioned hydraulic substance contains small amounts of Na2O and K2O as alkaline components. In particular, depending on the type of amorphous silicic acid, the content of alkali components may be quite large. These alkaline components have a negative effect on the reinforcing effect of the acrylic fibers, so it is desirable that they be as small as possible, and the content thereof is preferably 3.3% by weight or less as an equivalent amount of Na2O (Na2O + 0.658K2O), and more preferably 3.0
% by weight or less.

[0013] In order to further exhibit the effects of the present invention, it is desirable to use an additive that accelerates the hydration reaction between calcareous material and amorphous silicic acid material, that is, a hydration reaction accelerator. Here, the hydration reaction accelerators include Mgcl2, Cac
Inorganic chlorides such as l2, inorganic Ca salts and C acetate
Examples include Ca salts of organic acids such as a, but among these, M
gcl2 is particularly preferred for obtaining high-strength inorganic molded products.

Furthermore, it is of course possible to incorporate crystalline silicic acid substances such as silica sand and silica powder within a range that does not significantly impair the effects of the invention.

Furthermore, in order to impart porosity to the inorganic molded product and reduce its weight, pearlite, shirasu balloons, glass balloons, etc. can be mixed as appropriate. In addition, to improve the fluidity of hydraulic materials, other fillers such as wood pulp, fibrillated acrylic and aromatic polyamide fibers, inorganic fibers such as wollastonite, edenite and sepiolite, mica, clay and bentonite are used. can be added or blended.

Next, the acrylic fiber used in the present invention is not particularly limited, but in order to withstand high-temperature alkali and enhance the reinforcing effect, the acrylic fiber is made of a high-strength acrylic polymer with a high degree of polymerization. Preferably, the fiber is an acrylic fiber with a high modulus of elasticity. For example, the intrinsic viscosity is 2.0 to 5.0
Highly polymerized acrylonitrile (hereinafter abbreviated as "AN")
It is desirable to use an acrylic fiber having a tensile strength of 10 g/d or more and an elastic modulus of 180 g/d or more.

[0017] Here, a specific example of the manufacturing method of the acrylic fiber used in the present invention will be explained.

First, as the AN-based polymer used for producing acrylic fibers, AN alone or at least 90%
Monomers copolymerizable with mol% of AN and 10 mol% or less of the AN, such as carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, and their lower alkyl esters, hydroxymethyl acrylate, and hydroxyethyl acrylate. Examples include copolymerizable monomers such as hydroxyalkyl acrylate containing a hydroxyl group of a carboxylic acid such as hydroxymethyl methacrylate, acrylamide, methacrylamide, α-chloroacrylonitrile, hydroxyethyl acrylic acid, allyl sulfonic acid, and methacryl sulfonic acid. However, among these copolymerizable monomers, acrylamides are particularly desirable since they can yield acrylic fibers with high strength.

These AN-based polymers include dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF).
, organic solvents such as dimethylacetamide (DMAc),
When dissolved in a concentrated aqueous solution of inorganic salts such as calcium chloride, zinc chloride, and rhodan soda, or in an inorganic solvent such as nitric acid, the solution viscosity is 2000 poise or more, preferably 3000 to 100 poise.
A spinning dope having a polymer concentration of 5 to 20% is prepared.

In order to produce dense fibers with as high strength and high modulus as possible and with little difference in internal and external structures from the solvent solution (spinning stock solution) of the highly polymerized AN-based polymer thus obtained, it is necessary to A so-called dry-wet spinning method is adopted in which the spinning stock solution of the AN-based polymer is once discharged into an inert atmosphere such as air through a spinneret, and then the discharged spinning stock solution is introduced into a coagulation bath to complete coagulation. , highly oriented is desirable. The specific conditions for this wet-dry spinning are such that the distance between the spinneret surface and the coagulation bath liquid level is 1.
After discharging into a microspace formed by the spinneret surface and the coagulation bath liquid level, which is set within a range of ~20 mm, preferably 3 to 10 mm, the fiber yarn is introduced into a coagulation bath and coagulated, and then the obtained fiber yarn is The strip is subjected to post-processing steps such as water washing, solvent removal, primary stretching, drying/densification, secondary stretching, and heat treatment in a conventional manner to form a drawn fiber yarn. The fiber yarn obtained by this dry-wet spinning has extremely excellent drawability, but preferably the secondary drawing method is at least 1.1 times, preferably 1.5 times, under dry heat at 150 to 270°C. or more, and the total effective stretching ratio is at least 10 times, preferably 1
It is preferable to stretch it so that it is twice or more, and the fineness thereof is in the range of 0.5 to 7 deniers (d), preferably 1 to 5 denier (d). If the fineness is smaller than 0.5 d, thread breakage will occur frequently during the drawing process, and if it is larger than 7 d, high strength cannot be expected, which is not preferable.

The acrylic fiber thus obtained is cut into fiber lengths of 5 mm or less, preferably 2 mm or less, in order to improve dispersibility in hydraulic substances. In particular, high-speed rotating blades,
By crushing machines such as refiners, high-speed hammers, and high-speed jet flow, fiber length of 0.5 mm or less is reduced to 30% by weight.
As mentioned above, acrylic fibers cut to preferably 50% by weight or more are preferably used. At this time, the fiber length can be controlled by adjusting the grinding time and the output of the grinder, or by classifying the fibers using screens of different diameters.

[0022] Thus, the above-mentioned composition consisting of acrylic fibers, hydraulic substances and various fillers is mixed with water in a mixer, kneaded, and then extruded. At this time, the blending amount of the acrylic fiber is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight. Also,
As the mixer, an omni mixer, an Eirich, a kneader, etc. can be used. By the way, the amount of water added (w/c) to 100 parts by weight of the hydraulic material is preferably 50 parts by weight or less, more preferably 40 parts by weight or less,
Particularly preferably, it is 30 parts by weight or less. Here, if the amount of water added is more than 50 parts by weight, it becomes difficult to obtain a high-performance inorganic molded product. In particular, in the papermaking method that uses a slurry consisting of a hydraulic substance and a large amount of water, a high-strength inorganic molded product can be produced after autoclave curing, regardless of whether the silicic acid is amorphous or crystalline. Generally difficult to obtain.

[0023] Next, the molded product extruded as described above is put into an autoclave and cured under steam at 180°C, for example. 100-180 as curing temperature
Of course, there is no problem in using the temperature range of °C. Further, the curing time varies depending on the curing temperature, but is used in the range of 3 to 15 hours.

The thus obtained molded article of the present invention fully exhibits the reinforcing effect of the acrylic fibers, has extremely high bending strength, and has excellent dimensional stability.

[0025] In the field of molded products such as the present invention, the bending strength generally increases with the specific gravity of the molded product, so the effect of the present invention is examined by taking into account the influence of this specific gravity. It is suitable for expression, and in particular, it is suitable to evaluate using the "specific bending strength" value, which is the bending strength divided by the square of the specific gravity. In the molded products of the present invention, such specific bending strength is generally at a very high level of 80 kg/cm2 or more, which is an extremely high level not found in conventional similar products. In the molded article of the present invention,
More preferably, the value is 90Kg/cm2 or more,
More preferably, it is 95 kg/cm2 or more, and the hydraulic inorganic molded article according to the present invention having such physical properties is an extremely novel and excellent product.

[0026] Here, the bending strength and specific gravity are measured from a molded product, with the molding direction as the longitudinal direction, length 15 cm x width 4 cm x
A test piece with a thickness of 6 mm was cut out and JIS A 14
This value is measured as follows in accordance with 2008.

Bending strength: Span 10 in air dry condition
A bending test is performed on the test piece at a loading rate of 1 mm/min, and the bending strength (Kg/cm2) is calculated by a conventional method.

[0028] Specific gravity: The saturated weight and underwater weight of the test piece were measured using water at 20°C, and then the absolute dry weight was measured after drying at 105°C for 24 hours, and the bulk specific gravity was calculated using the following formula.

Specific gravity = bone dry weight / (saturated water weight - weight in water)

[0030]

[Effect of the invention] The hydraulic inorganic molded product according to the present invention is
It is obtained by extrusion molding a mixture of cement, a hydraulic substance whose main raw materials are amorphous silicic acid, and acrylic fibers, and then curing it in an autoclave. It has high bending strength and excellent heat resistance, impact resistance, and dimensional stability.

[0031] Therefore, its excellent performance can be utilized in many applications such as building materials and civil engineering materials.

[0032]

[Examples] The effects of the present invention will be specifically explained below with reference to Examples.

Examples 1 to 8, Comparative Examples 1 to 2 AN made of 100% acrylonitrile (AN) and having an intrinsic viscosity of 3.2
The polymer was solution polymerized in dimethyl sulfoxide (DMSO), and the resulting spinning stock solution was wet-dry spun. As a coagulation bath, a 55% DMSO aqueous solution at 20° C. was used. The obtained undrawn fiber yarn was stretched 5 times in hot water, washed with water, and then subjected to secondary stretching at 90% of the maximum stretching ratio in a dry heat tube at 180 to 200°C to obtain a fineness of 2 denier and a strength of 11. .7g
/d, an elongation of 11.8%, and an elastic modulus of 200 g/d. This acrylic fiber was cut into a fiber length of 2 mm.

Next, Portland cement (equivalent Na2O content 1.0% by weight) was used as the cement, and fly ash A (equivalent Na2O content of 1.0% by weight) with a particle size of 10 to 20μ was used as the amorphous silicic acid.
O amount 1.8% by weight) and fly ash B (equivalent N
a2 O content 3.5% by weight), silica fume with a particle size of 0.2μ (equivalent Na2O content 1.2% by weight), and silica sand with a particle size of 10μ as crystalline silicic acid (equivalent Na2O content 0.2% by weight). ) were used in the formulation shown in Table 1, and 1 part by weight of acrylic fiber and 1 part by weight of methyl cellulose were added to 100 parts by weight of these hydraulic substances.
After 5 parts by weight and Mgcl2 were blended and mixed in an Eirich, water was added and kneaded. The obtained viscous material was extrusion molded into a molded plate having a thickness of about 6 mm. The obtained molded plate was left in a wet state for 24 hours and in 70°C steam for 4 hours, and then cured in steam for 5.5 hours in an autoclave at 180°C.

The bending strength of the obtained molded plate was measured and the specific bending strength was evaluated. The results are shown in Table 1. It can be seen from Table 1 that the molded plate of the present invention has excellent reinforcing performance.

[0036]

[Table 1]

Comparative Examples 3 and 4 Acrylic fibers similar to those used in Example 1 were cut to a fiber length of 5 mm.

Next, as in Example 1, Portland cement as cement, fly ash as amorphous silicic acid, and silica sand as crystalline silicic acid were used in the proportions shown in Table 1, and acrylic was added to 100 parts by weight of these hydraulic substances. 1 part by weight of fiber and 2 parts by weight of wood pulp were blended, and water was added to this to form a slurry with a solid content concentration of 5% by weight. Next, anionic polyacrylamide polymer flocculant 10 was added under low speed stirring.
0 ppm was added. 50% of the obtained cement slurry
A molded plate with a thickness of about 6 mm was made by forming a sheet using a wire mesh.

[0039] After the obtained molded plate was cured in an autoclave in the same manner as in Example 1, the bending strength was measured, and the results of evaluating the specific bending strength and the like are shown in Table 1. The comparative example is
In both cases, the bending strength, especially the specific bending strength value, is low, and it can be seen that the bending strength is clearly inferior to that of the present invention.

Claims (4)

[Claims] Claim 1: A molded product made by extrusion molding a mixture of a hydraulic material mainly made of cement and amorphous silicic acid, and acrylic fibers and then curing in an autoclave, the bending strength of which is expressed as the square of the specific gravity. The specific bending strength divided by 80Kg/cm2
A hydraulic inorganic molded product characterized by exhibiting the above characteristics. Cement, a hydraulic substance whose main raw material is an amorphous silicic acid substance with a weight average particle size of 1 μ or more and an amorphous silicic acid substance with a weight average particle size of less than 1 μm, and an acrylic material. After kneading the mixture with fibers with water, extrusion molding,
A method for producing a hydraulic inorganic molded product, which is then subjected to autoclave curing. Claim 3: A claim characterized in that the amorphous silicic acid having a weight average particle size of 1 μ or more is fly ash, and the amorphous silicic acid having a weight average particle size of less than 1 μ is silica fume. 2. The method for producing a hydraulic inorganic molded product according to 2. 4. The method for producing a hydraulic inorganic molded article according to claim 2 or 3, wherein a hydration reaction accelerator is added to the hydraulic substance.