JPS61151051A - Fiber reinforced cement material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cement material reinforced with fibers. It is useful as building materials such as timber and date, and as civil engineering materials.

Prior Art Traditionally, natural asbestos has been, and is still the most commonly used, reinforcing fiber for cement. Other reinforcing fibers include polyvinyl alcohol fibers, glass fibers, carbon fibers, aramid fibers, acrylic fibers, and the like.

Problems to be Solved by the Invention The fibers conventionally used as cement reinforcing fibers have their own problems.

In other words, the production of high-quality natural asbestos has been in short supply for the past several years, and asbestos has now become one of the natural resources that will be exhausted in the near future. In terms of pollution, its use is likely to be banned in the near future due to its harmful nature.

Furthermore, although polyvinyl alcohol fibers certainly have excellent mechanical properties, their mechanical properties are significantly reduced during treatment under alkaline conditions (treatment at high temperatures) during the cement manufacturing process. It will be done.

Furthermore, known fibers such as glass fibers, carbon fibers and aramid fibers either lack alkali resistance or are too uneconomical to maintain their desired affinity for the cement matrix. Therefore, it is out of the question to use these fibers for cement reinforcement.

Finally, with regard to tetraacrylonitrile fibers, conventional ones have been unsuitable for reinforcing cement due to their mechanical properties, alkali resistance, etc.

In addition, although products with improved properties have recently been known, their adhesion to cement is still insufficient. In the present invention, a material with satisfactory mechanical properties and alkali resistance for reinforcing cement is used, and the adhesion with cement is also sufficiently improved. It can be reinforced with fibers to provide a sub-cement material.

Means for Solving the Problems According to the present invention, a cement material reinforced with fibers is provided, and this cement material contains 2.5 to 30% by weight of methacriconitrile, acrylonitrile and 5 to 0% by weight of copolymerizable vinyl monomer
It is characterized by containing acrylic fibers consisting of and acrylonitrile.

Cement materials generally have low elongation and high initial modulus, but poor toughness. In other words, when a load is applied, once cracks occur, cracking occurs due to the lack of toughness. In order to solve this problem, various inorganic and organic polymer viscosity, natural minerals (asbestos), organic fibers, inorganic fibers, etc. have been introduced into cement materials as reinforcing materials. Comes with improved strength and toughness. In particular, asbestos, a natural mineral,
Due to its mechanical properties and cost, it has been mainly used as a cement reinforcement material. However, today, the use of asbestos is being heavily regulated due to pollution problems.

Various organic fibers are currently being talked about as reinforcing materials. Among them, vinylon (polyvinyl alcohol fiber) is highly valued due to its excellent mechanical properties and alkali resistance.
It has been used as a cement reinforcing material. However, vinylon also has disadvantages, and there is a limit to the temperature at which it can be cured when curing the cement material. That is, 110℃
If vinylon-reinforced cement material is cured at temperatures above, the vinylon fibers will deteriorate and will not function as a reinforcing material, resulting in no improvement in the mechanical properties of the cement material. However, curing at high temperatures is important in improving the productivity of cement materials.

Therefore, we improved the mechanical strength and toughness of cement materials,
As a result of intensive research into reinforcing materials that can withstand high-temperature curing, it was found that cement materials using acrylic fibers as reinforcing materials have improved toughness and mechanical strength. Acrylic fibers known so far have low mechanical strength and alkali resistance and are not suitable as reinforcing fibers. In addition, although acrylic fibers with improved properties have recently become known, their adhesion to cement -1i is still insufficient. The acrylic fibers used in the cement composite material of the present invention have excellent root zone strength and alkali resistance, and have improved adhesion to cement.

The acrylic fiber used as this reinforcing material will be described in more detail. The acrylic fibers are composed of 2.5 to 30% by weight of methacriconitrile (preferably 10 to 20% by weight q6), 5 to 0% by weight of a vinyl monomer copolymerizable with acrylonitrile, and acrylonitrile. If methacrylonitrile is less than 2.5% by weight, alkali resistance deteriorates, inside cement (under alkaline atmosphere)
In addition, the mechanical properties of the fibers deteriorate, and fibrillation of the fibers during kneading with cement becomes difficult to occur, resulting in a decrease in adhesion with cement, making it impossible to obtain the desired cement material. Furthermore, if the methacrylonitrile content is greater than 30% by weight, no improvement in the mechanical properties of the fibers themselves can be expected, and as a result, a cement composite with improved mechanical properties cannot be obtained.

Acrylonitrile polymers having such a composition can be obtained by conventional aqueous suspension polymerization or solution polymerization using an organic solvent. Vinyl monomers copolymerizable with acrylonitrile include methyl acrylate, methyl methacrylate, acrylamide, methacrylamide, itaconic acid,
maleimide, allyl alcohol, methallylamine, β-
Examples include, but are not limited to, hydroxyethyl methacrylate, β-aminoethyl methacrylate, and acrylic acid.

The acrylic polymer thus obtained can be treated with organic solvents such as dimethylformamide, dimethylacetamide, and trimethylsulfamide, nitric acid, sulfuric acid, and sodium thiocyanate (
Rodan salt), dissolved in an inorganic solvent such as an aqueous zinc chloride solution to prepare a spinning stock solution. This spinning stock solution is spun using a dry or wet spinning method, solidified, and then subjected to solvent stretching and washing with water.

After washing with water, f) stretching is performed using a medium such as boiling water, glycerin, or steam. The total stretching ratio from spinning is 9 to 20 times, preferably 11 to 16 times.

If it is less than 9 times, the target mechanical strength cannot be obtained, and 2
If it is larger than 0 times, stretching becomes impossible and yarn breakage occurs frequently.

The thus obtained drawn yarn is dried and densified in a dryer under full length or tension, and then drawn again under dry heat or moist heat. The stretching ratio is 1.1 to 1.4 times,
If it is less than 1.1 times, it is difficult to obtain the target mechanical properties.
If it is larger than 1.4 times, thread breakage occurs frequently and uniform fibers cannot be obtained.

The redrawn fibers are finally heat set. If it is not heat-set, it will shrink due to the alkaline solution when mixed with cement, its mechanical properties will deteriorate, and it will no longer function as a reinforcing fiber. The single fiber strength of the acrylic fiber obtained through the above manufacturing process is 611/ci or more, the initial elastic modulus is 850 kg/a2 or more, which is high strength and high elastic modulus, and has good adhesion to cement. , an acrylic fiber with excellent alkali resistance. The fibers were mixed with Portland cement furnace solution (alkaline solution: pH=12).
The strength retention rate after 8 hours of treatment at 0C was 85.
It is superior in quality and is comparable as a cement reinforcing material.

Physical properties of acrylic fiber containing methacrylonitrile used in the present invention and treatment with cement solution (
Tables 1 and 2 show the fiber properties after heating at 80°C for 8 hours.

Furthermore, the acrylic fiber containing methacrylonitrile used in the cement material of the present invention has a property of being easily fibrillated when mixed with cement. The reason for this is not clear, but the inclusion of methacrylonitrile changes the crystallinity within the acrylic fiber.
This is thought to be because it tends to become brittle. This fibrillation increases the adhesion between reinforcing fibers and cement, increasing the mechanical strength of the cement material.
considered to be a thing. Therefore, its mechanical properties are superior compared to conventional acrylic fibers or cement materials containing recently known acrylic fibers with improved mechanical properties and alkali resistance.

Further, the thickness of the fibers used in the cement material of the present invention is preferably 0.5d to 10.5d. When used as a cement reinforcing material, it is preferably cut into lengths of 3 m to 20 m. If the length is shorter than 3 m, it will not contribute much to the effect as a reinforcing material, and if the length is longer than 20 tremors, the fibers tend to bead-like when mixed into cement and have no reinforcing effect. decreases. The fibers can sufficiently maintain their physical properties even in a high-temperature alkaline atmosphere, and greatly improve the bending strength and toughness of cement materials. In addition, the bending strength of the cement material after cracking shows an increase in rupture strength, and the strain at the highest load after cracking shows a large value. That is,
An increase in the amount of strain at the highest load after cracking improves toughness, leading to improved toughness, which provides improved bending strength and high energy absorption ability.

The fibers can be used alone or mixed with other organic synthetic fibers such as steel fibers, alkali-resistant IJ ff fibers, HolJ vinyl alcohol, asbestos pulp, and polyethylene and nylon. The cement is an ordinary hydraulic cement, and ordinary Portland cement, early-strength Portland cement, sulfate-resistant Portland cement, and white Portland cement are used.

Mixed cement is also not limited to blast furnace cement,
Silica cement and fly-assy cement can also be used.
In addition, alumina cement, expansive cement, and ultra-early strength cement can also be used. In addition, as admixtures, fluidizing agents, water reducing agents,
It is also possible to use a mixture of thickeners, water retention agents, and water repellents. The content of the fibers in cement is preferably 0.
．． It is 5% to 10% by weight.

When the fibers are mixed with cement, the fibers have good affinity with the cement, and there are no particular problems with dispersibility. Furthermore, when producing cement material by the papermaking method, the fibers hardly fall off from the cement because of their good affinity with cement.

The cement materials produced in this way can be used for slate materials, roofing materials, tiles, etc., and specific products include sewer pipes, housing exteriors (walls, soundproofing materials), tiles, etc.
There are flower pots etc. In particular, when used for roofing or housing exteriors, the cement material of the present invention has improved bending strength and toughness, so it can be seen to improve workability not only during use but also during construction. In particular, it has the property of not being easily cracked during nailing, quarter-inching, and cutting when used manually.

Example Examples of the cement material of the present invention are shown below.

Example 1 Methacrylonitrile 1.5% by weight, 2.5% by weight, 1
0% by weight, 20% by weight, 30% by weight, 35% by weight and acrylonitrile by 98.5% by weight, 97.5% by weight, 90% by weight, 80% by weight, 70% by weight, 65% by weight, respectively.
The copolymers were collected and polymerized by an aqueous suspension polymerization method to obtain six types of copolymers. Each of these copolymers was dissolved in a 68% nitric acid aqueous solution to obtain a spinning stock solution, and then these spinning stock solutions were coagulated in a dilute aqueous solution of nitric acid by a wet spinning method. A fiber with a stretching ratio of 16 times was obtained. The fibers themselves are fixed by heat setting, and each fiber is
Please cut to ■.

Water reducing agent (sodium naphthylsulfonate) added to 35 parts of the above fiber.
Impregnate. After sufficient impregnation, squeeze out excess water reducing agent. Cement (early strength Portland cement): The water reducing agent-attached fibers are thoroughly mixed and dispersed in a mixture of 3,000 parts and 50 parts of water. Use this as a mold (15cIn length x 4CM width x 1.5m thickness)
The mixture is poured into a molded body. This molded body was cured in a humid atmosphere at 80°C to obtain a fiber-containing cement material. The physical properties of the cement material are shown in Table 3 on the next page. The dimensions of the cement material sample are 15 crn (length) x 4. m (width) Xl, 7c
It is rIt (thickness), and its length is IO.

The bending strength was measured using Instron TT-OMt-. In addition, tests on test pieces were conducted after 7 days of curing.
Row 7° 1・ Below margin Example 2 Methacrylonitrile 2.5% by weight, 10% by weight, 20
2% by weight, 30% by weight, and 2% by weight of methyl acrylate, respectively.
Acrylic yarn fibers having compositions of 95.5% by weight, 88% by weight, 78% by weight, and 68% by weight of acrylonitrile, respectively, were prepared in the same manner as in Example 1.
To force, to. A test piece is prepared using a simple paper-making device, and 30 parts of the above-mentioned fibers are each coated with a sample. 80 parts of cement, 1000 parts of cement (early strength Portland cement) and 2500 St of water were mixed for 15 minutes in a cement mixer. A board with a thickness of 6 sheets was made from this mixture using a simple paper-making device (during paper-making, a saccharging pressure of 200 to 300 mHg was applied, and then a pressure of 50 kg/crn' was applied for 10 minutes, followed by curing at 80°C). .

The bending strength and strain of the four types of test specimens prepared above were measured. The measurement results for the cement material are shown in Table 4 on the next page. The dimensions of the cement material sample are 25 cm (length)
Example 3: 10% by weight of methacriconitrile and 90% by weight of acrylonitrile
Acrylic fiber used in the cement material of the present invention consisting of a weight factor (A), a conventionally known acrylic fiber for clothing (B), an acrylic fiber with excellent mechanical properties and alkali resistance (C), and Vinylon CD, which is used for cement reinforcement, are each made into a cement composite by the method of Example 1. When curing these cement composites, the curing temperature was changed to 800°C, 110°C and 140°C, and each composite was treated for 8 hours. Table 5 shows the physical properties of the cement composite prepared above and the physical properties of the fiber itself.
Shown below. The test pieces were measured after being cured for 7 days.

Claims (1)

[Claims] 1. Methacrylonitrile 2.5 to 3 as reinforcing fiber
1. A fiber-reinforced cement material characterized by containing acrylic fibers consisting of 0% by weight, 5 to 0% by weight of a vinyl monomer copolymerizable with acrylonitrile, and acrylonitrile.