JPS6117780B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing fiber-reinforced cement products in which linearly coordinated aromatic polyamide fibers and polyolefin or/and polyamide synthetic fibers are simultaneously mixed into cement. Cement products are characterized by high compressive strength, but on the other hand, their bending strength and bending strain at break are low, so they have a low energy absorption capacity, which makes them susceptible to damage or collapse due to small impact forces. had. In order to correct this drawback, it has recently been proposed to incorporate inorganic fibers such as asbestos fibers, steel fibers, and glass fibers, and organic fibers such as nylon and polypropylene into cement as reinforcing materials for cement products. However, although inorganic fiber-reinforced cement products such as glass fiber have high bending strength, they have the disadvantage that their energy absorption capacity is lower than that of organic fiber-reinforced cement due to the low strain at bending break. Organic fiber-reinforced cement is characterized by its excellent impact resistance and high energy absorption capacity, but its bending strength is lower than that of inorganic fiber-reinforced cement, so it is not suitable for fields that require strength. It could not be applied, and its scope of application was naturally limited. Under these conditions, it has both high bending strength and impact resistance. In other words, there is a method for manufacturing fiber-reinforced cement products having excellent physical properties by simultaneously using inorganic fibers and organic fibers such as nylon and polypropylene and mixing them into cement products to overcome their mutual disadvantages. Kosho 43-
2119, known as Special Publication No. 52-30968. However, in Japanese Patent Publication No. 43-2119, a polyacrylamide coagulant was added to a large amount of water, and 5 to 30 inorganic fibers were added in a weight ratio to the amount of cement used.
This method is characterized by adding 1% to 5% synthetic fiber and stirring, then adding the required amount of Portland cement and stirring to remove excess water, followed by molding. In this case, there is no problem with synthetic fibers, but inorganic fibers, such as commonly commercially available glass fibers, have insufficient corrosion resistance in alkaline aqueous solutions and are subject to corrosion over time, losing their inherent tensile strength. The strength gradually disappears, and therefore, when glass fibers are mixed into cement mortar or concrete paste, this disadvantageous phenomenon occurs due to the basicity of calcium hydroxide generated from these components. However, there was a defect that the effect of mixing glass fiber disappeared. Other inorganic fiber reinforcing materials include asbestos fiber and steel fiber, but asbestos fiber is a natural product, and there are concerns that the raw material will run out in the future, and in reality, it is feared that quality will decline and prices will rise. has been done.
Furthermore, even if it is put into practical use, the fiber length is short, the fiber diameter is small, and it is almost powder-like, so there are problems with adverse health effects on the human body and there are many difficulties in handling it. It has the disadvantage that it is difficult to obtain a reinforcing effect. In addition, steel fibers have the problem of rusting due to water and moisture, and in such an atmosphere, the fibers corrode over time and the reinforcing effect decreases, and the surface of cement products may have stains due to rusting. It has disadvantages such as the occurrence of Japanese Patent Publication No. 52-30968 discloses the use of specific glass fibers that are resistant to alkaline aqueous solutions, polyolefin fibers such as polypropylene, or nylon 6,
This method of manufacturing fiber-reinforced cement products is characterized by the simultaneous use of polyamide fibers such as 66 nylon, which are used as reinforcing materials for various cement products, but this method almost eliminates the problem of the alkali resistance of glass fibers. Even if it is not, as long as glass fiber is used, there are disadvantages peculiar to glass fiber, such as glass fiber's lack of flexibility and being easily damaged during handling or mixing and dispersing in cement. Reinforcement of reinforced cement products obtained due to the fact that the strength is not fully utilized and the strength is very low for practical use, and the fibers are likely to break due to mechanical stress when mixed and dispersed with cement. The effects may not be as good as expected from the original physical properties of the fibers, or in order to solve these problems, it is necessary to pay close attention to the handling of the fibers, including problems with the working environment. However, there are drawbacks such as limited equipment for mixing and dispersing glass fiber and cement. The inventors of the present invention have conducted extensive studies on reinforcing materials that have an excellent reinforcing effect for cement products without being affected by the basicity of calcium hydroxide and other substances generated in cement components. It was discovered that aromatic polyamide fibers have excellent resistance to alkaline aqueous solutions, and that fiber-reinforced cement products thereof have higher bending strength and slightly higher energy absorption capacity than glass fiber-reinforced cement products, and the present invention was developed. It has come to completion. The purpose of the present invention is to provide excellent alkali resistance when used as reinforcing fibers for fiber reinforced cement products.
Linear aromatic polyamide fiber has high bending strength but insufficient energy absorption ability, excellent alkali resistance, high impact resistance,
By simultaneously using polyolefin and/or polyamide fibers, which have energy absorption ability but have the disadvantage of low bending strength, as a reinforcing material for various cement products, it is possible to achieve permanent excellent bending strength and impact resistance. The present invention provides a method for producing a cement product having various physical properties. That is, the present invention provides linear aromatic polyamide fibers with a single yarn fineness of 1 to 10 denier and a fiber length of 3 to 50 mm, and single yarn fibers with a single yarn fineness of 3 to 100 denier and a fiber length of 3 to 50 mm.
This is a method for producing a fiber-reinforced cement product, characterized in that polyolefin and/or polyamide synthetic fibers are simultaneously mixed into cement in a weight ratio of 3:1 to 1:8. The linear aromatic polyamide used in the practice of the present invention has the general formula -NH-Ar-NHCO-
Polyamides and copolyamides consisting of units Ar'-CO- or/and -NH-Ar''-CO-, in which Ar, Ar', and Ar'' each consist of an aromatic hydrocarbon or a heteroaromatic ring. is a divalent organic group,
In each group, the bond that extends the molecular chain by bonding to the amide group coordinates linearly on the aromatic ring. That is, the bonding hands protrude in opposite directions on the same axis or on a parallel axis to the ring. In other words, it means a polyamide in which bonds are coordinated at positions that are point symmetrical with respect to the center of the aromatic ring. Specifically, Ar,
Ar' and Ar'' are paraphenylene, 4,4'-biphenylene, 1,4- or 1,5 or 2,6-naphthalene, 2,5-pyridylene, etc., and each of them has one or more groups such as alkyl or halogen. This can be exemplified by two or more substituted groups. Also, as a special example of these divalent groups, the general formula

There is a divalent group represented by the formula [Formula], where × is composed of a chain of even numbers of atoms of 4 or less, and
For example, -CH ₂ -CH ₂ -, trans-CH=CH
-, -N=N-, -C=N-,

【formula】

【formula】

【formula】

[Formula] etc., the number of atoms connecting two phenyl rings is an even number of 4 or less when counted along the chain. Furthermore, one or two of the two phenyl rings in the above general formula may be replaced with other linearly coordinating aromatic rings. Furthermore, Ar, Ar', and Ar'' may be divalent groups having the same effect in addition to the above-mentioned linearly coordinating aromatic groups, and specifically, they include trans ethenylene, ethynylene, trans, trans -1,4-butadienylene, etc. Ar, Ar', Ar'' in each unit constituting the polymer may be two or more types, and Ar,
Ar′, Ar″ may be the same or different. However, in the polymer of the present invention, approximately 5
Less than mol% of units other than the above, i.e., divalent groups other than aromatic rings such as tetramethylene and hexamethylene, aromatic rings whose coordination is in the meta position, or between phenyl rings such as diphenyl ether and benzophenone. Substitution of an aromatic ring connected by an odd number of atoms or a bonding group other than amide, such as an ester group or a urethane group, is also allowed as long as the effects of the present invention are not impaired. The polymer characterized by the present invention having the structure described above includes homopolymers and copolymers, and copolymers include block copolymers in which copolymer components are regularly introduced into the molecular chain, and so-called regular copolymers. It may be a random type copolymer, or a mixture of two or more types of polymers may be used in fiber production. Typical examples of these linear aromatic polyamides are poly parapenzamide, poly paraphenylene terephthalamide, poly 4,4'-diaminobenzanilide terephthalamide, poly N,N'-P-phenylene bis( P-benzamide) terephthalamide, polyparaphenylene
2,6-naphthalicamide, copolyparaphenylene/4,4'-(3,3'-dimethylbiphenylene)-terephthalamide, copolyparaphenylene/2,5-pyridylene-terephthalamide, copolyparaphenylene Examples include nylene terephthalamide/pyromellituimide, copolyparaphenylene-isocincomelonamide/terephthalamide, and the like. These linearly coordinated aromatic polyamide polymers are produced from aromatic dicarboxylic acids, aromatic diamines, and aromatic aminocarboxylic acids corresponding to each unit by a conventionally known method. in particular,
A method is used in which a carboxylic acid group is first induced into an acid halide, acid imidazolide, or ester and then reacted with an amino group, or a method in which an amino group is induced into an isocyanate group and then reacted with a carboxylic acid group. Also, so-called interfacial polymerization, low-temperature solution polymerization, etc. may be used. The degree of polymerization of the polymer of the present invention is not particularly limited, but if it is too low, good mechanical properties of the fibers cannot be satisfied.
Logarithmic viscosity (ηinh) measured by dissolving 0.5 g of polymer in ml of 0.8 to 1.0 or more, more preferably 2.0
The above is selected. The method for producing the linearly coordinated aromatic polyamide fiber used in the present invention is not particularly limited.
- Optical anisotropy dissolved in so-called N-alkyl substituted amide type solvents such as methyl-2-pyrrolidone and hexamethylphosphoramide, combinations thereof, and solvents to which inorganic salts such as lithium chloride and calcium chloride are added. Or spinning an optically isotropic dope, or an optically anisotropic or optically isotropic dope prepared by dissolving a linearly coordinated aromatic polyamide in 98% by weight or more of an inorganic solvent such as concentrated sulfuric acid, chlorosulfuric acid, or fluorosulfuric acid. By extruding the dope directly into the coagulating liquid through a spinneret and wet spinning, or by extruding the dope through a spinneret over a short distance into a gaseous medium or an inert non-coagulating medium such as toluene or heptane and then introducing it into the coagulating liquid. Although it can be obtained by space discharge wet spinning, the combination of an optically anisotropic dope and space discharge wet spinning is a more preferred method for producing fibers with particularly excellent mechanical properties. Linearly coordinated aromatic polyamide fibers have high strength and Young's modulus even as they are spun, as expected due to the rigidity of their molecular structure and intermolecular attraction, and can be used as reinforcing fibers in cement products. , further heat-treating the spun fibers under tension or in a relaxed state at a temperature of 200°C or higher, generally 300°C or higher, to impart higher strength, Young's modulus, crystallinity, etc. to the fibers for use. is a more preferred embodiment from the viewpoint of further improving the alkali resistance of the fibers and further improving the bending strength reinforcing effect of the cement product. As a heating method for such heat treatment, for example, a method in which the fiber is passed through a heating pin, a heating plate, a heating tube, or a heating slot, a method in which the fiber is passed through a heating gas furnace, a liquid heating bath, etc. are used. In this case, the atmosphere around the fibers is preferably an inert atmosphere such as nitrogen or argon. The aromatic polyamide fiber used in the practice of the present invention has excellent resistance to alkaline aqueous solutions.
After immersing in 1000 c.c. of aqueous solution and heating at the same temperature for 1 hour in a closed system, then washing thoroughly with water and drying, the weight is expressed as W (g).
The alkali solubility, which is one of the measures of alkali resistance calculated using the following formula, 2-W/2 (%), is 0.5.
% or less and the tensile strength of the sample obtained by thoroughly washing with water and drying after 6 hours of treatment under the same conditions is _T1
(Kg/mm ² ) and Young's modulus as Y ₁ (Kg/mm ² ), tensile strength before alkali treatment as T ₀ (Kg/mm ² ), and Young's modulus as Y ₀ (Kg/mm ² ). , the strength retention rate expressed by the formula, T ₁ /T ₀ ×100 (%), and the formula, Y ₁ /Y ₀ ×10
The Young's modulus retention expressed as 0 (%) is
Has resistance to alkaline aqueous solution of over 95%. In addition, this linearly coordinated aromatic polyamide fiber is
When measured as a single yarn, the tensile strength is usually 150 Kg/mm ² or more, preferably 250 Kg/mm ² or more and 4×10 ³
It has mechanical properties characterized by a tensile Young's modulus of Kg/mm ² or more, preferably 5.0×10 ³ Kg/mm ² or more, and the fineness of the single fibers constituting the fiber is 1 to 10 deniers. are carefully selected and used depending on the purpose and use. If the single filament fineness of the fibers is smaller than the above range, not only will it be difficult to manufacture the fibers, but also the dispersion will be non-uniform when dispersed in cement, which is undesirable.
On the other hand, if the single fiber fineness exceeds the above range, it will not only be difficult to produce fibers with excellent tensile strength and Young's modulus, but also reduce the free contact surface with cement, making it difficult to produce cement products. Reinforcement effect deteriorates. In this sense, the single fiber fineness of the single fibers constituting the linearly coordinated aromatic polyamide fiber is 1.
-10 denier, more preferably 1-6 denier. The linearly coordinated aromatic polyamide fibers are mixed and dispersed in cement together with the polyolefin and/or polyamide fibers, but at that time the fibers are cut into fiber lengths of 3 to 50 mm. If the fiber length is shorter than the above range, a sufficient reinforcing effect cannot be obtained, and if it is too long, the dispersibility in cement will be poor and the fibers will become non-uniform, which is not preferred. In the method of the present invention, the synthetic fibers to be used together with the linearly coordinated aromatic polyamide fiber mentioned above include polyolefin fibers represented by polypropylene, polyethylene, etc., nylon 6, nylon 66, nylon 6,10, nylon 12, etc. Polyamide fibers other than linearly coordinated aromatic polyamides such as aliphatic polyamide alone or copolymerized polyamide fibers, 6T nylon containing an aromatic ring, and poly-metaphenylene isophthalamide can be effectively used. These fibers have sufficient alkali resistance, e.g. 50%
It has extremely strong corrosion resistance even against concentrated alkalis, and its weather resistance is also extremely stable and shows no tendency to decline.
In particular, polyolefin fibers are stable. The synthetic fibers used in the present invention made of such polyolefin and/or polyamide have a single yarn fineness in the range of 3 to 100 deniers, and may be used in any combination or alone depending on the purpose and use, but the fineness is finer than the above range. In this case, not only is it difficult to manufacture the fiber, but also it becomes non-uniform when used in a dispersed manner, which is not preferable. On the other hand, if the fineness is thicker than the above range, the free contact surface with cement will decrease, and the miscibility with the linearly coordinated aromatic polyamide fiber, which is the other reinforcing fiber used in combination, will also decrease, which is not preferable. For such reasons, preferably 5 to 100 denier,
More preferably, a single yarn fineness in the range of 10 to 70 deniers is suitably used. The fiber length is cut to a range of 3 to 50 mm for the same reason as the linear aromatic polyamide fiber. In the method of the present invention, the ratio of linearly coordinated aromatic fibers to polyolefin or/and polyamide synthetic fibers is such that the linearly coordinated aromatic polyamide fibers have excellent bending strength and the polyolefins or/and polyamide synthetic fibers are used in combination.
It is necessary that the range is such that it can combine the excellent impact resistance and high energy absorption capacity of polyamide synthetic fibers, and for this purpose, the ratio of their combination should be 3:1 to 1:8 by weight. Within this range, fiber-reinforced cement products with excellent physical properties can be obtained. If the amount of linear aromatic polyamide fibers exceeds the above range, for example, curve A in the drawing
The bending stress-strain curve is similar to that of cement reinforced solely with linearly coordinated aromatic polyamide fibers, as shown in Figure 2. Although the bending stress is high, the stress drop against strain is significant, and it does not have sufficient energy absorption ability. On the other hand, if the amount of polyolefin and/or polyamide-based synthetic fibers is increased beyond the above combination range, the bending stress strain curve will be similar to that of cement reinforced solely with synthetic fibers, as shown by curve B in the same figure, and the bending stress strain curve will be insufficient. Although it has a good energy absorption ability, it is not preferable because the bending stress is significantly reduced. If the combined ratio is within the range of the present invention, a fiber-reinforced cement product can be obtained which exhibits excellent bending stress and sufficient energy absorption ability with little decrease in bending stress against strain, as shown by curve C in the drawings. For these reasons, the ratio of linearly coordinated aromatic polyamide fibers to polyolefin or/and polyamide synthetic fibers is in the range of 3:1 to 1:5, more preferably 2:1 to 1:5, by weight. is preferable, and a cement product having both the excellent bending strength and the excellent energy absorption ability of both fibers can be obtained. Methods for using linearly coordinated aromatic polyamide fibers and polyolefin or/and polyamide synthetic fibers include, for example, cutting fibers that have been set in advance to a predetermined mixing ratio, or cutting them separately and mixing them. Alternatively, any method may be used, such as mixing separately cut pieces in cement powder, cement paste, or water. The term "cement" as used in the present invention refers to general hydraulic cements such as Portland cement. special portland cement such as cement, titanium cement, manganese cement, chromium cement, mixed portland cement such as alumina cement, lime mixed cement, blast furnace slag mixed cement, porazone mixed cement, etc. alone or in combination. is used in its normal state as mortar or concrete. The methods of mixing these cements, linearly coordinated aromatic polyamide fibers, and polyolefin or/and polyamide synthetic fibers include a method in which fibers are dispersed in cement powder, and a so-called premix method in which fibers are dispersed and mixed in cement slurry. A spray-up method in which predetermined amounts of fibers and cement water are simultaneously sprayed, a so-called paper-making method, etc. are appropriately selected and mixed. In this case, prior to use, if necessary, it is permissible to remove oils etc. adhering to the fibers, and to add adhesion aids for the purpose of improving adhesion to cement. Also, sand, pebbles, crushed stone, refractory powder, blowing agents, commonly used in mixing fibers and cement,
If necessary, various additives such as aggregates and dispersants may be used in combination. Next, an example of an embodiment of the present invention will be shown. First, linearly coordinated aromatic polyamide fibers and polyolefin or/and polyamide fibers having a predetermined single-filament denier are prepared. These fibers are set in advance at a predetermined mixing ratio and cut into a predetermined length, or they are cut separately. When the fibers prepared in this manner are mixed with cement powder, the fibers and cement are mixed well in a constant ratio. When mixing with cement mortar or concrete, first mix the mortar or concrete according to the usual method.
Make slurry. In the case of concrete, the amount of sand is usually 1 to 3 times the amount of cement, and the amount of water to be added is about 40 to 80% by weight based on the cement. A predetermined amount of the above cut fibers is mixed and dispersed in the obtained paste. The thus obtained cement paste, in which the linearly coordinated aromatic polyamide fibers and polyolefin or/and polyamide fibers are added at the same time, is molded and cured and hardened according to a conventional method depending on the purpose of pouring or other use. Another advantage of using linear aromatic polyamide fibers as one of the reinforcing materials in manufacturing fiber-reinforced cement products is that unlike glass fibers, these fibers are highly flexible. The advantage of this product is that it has a high practical strength Young's modulus with almost no damage to the fibers during handling, and has good reinforcing efficiency for cement products because the fibers are almost never cut when mixed and dispersed with cement. Because the fiber has extremely good alkali resistance, it can be cured at high temperatures, such as 150°C, which is currently impossible not only for ordinary glass fibers, but also for alkali-resistant glass fibers.
Since autoclave curing at ~200°C is possible, the production efficiency of reinforced cement products is very high, and high temperature curing is possible, which has the advantage of increasing the strength of the cement itself. Cement products that can be manufactured by the method of the present invention include ordinary press, autoclave, resin impregnation,
It covers all types of cement products such as lightweight foam, asbestos cement, asbestos calcium silicate substitutes, etc. Its specific uses include building walls, floor concrete, finishing mortar, waterproof concrete, and waterproof mortar. , protective concrete or mortar for waterproof membranes in buildings, concrete or mortar pavement for steel plate floors,
Concrete or mortar water tanks, pools, pipes, ducts, etc. for road and pedestrian bridges. In this way, a fiber obtained by the method of the present invention is obtained in which linearly coordinated aromatic polyamide fibers with high strength and high Young's modulus that are resistant to alkaline aqueous solutions are used in combination with polyolefin or/and polyamide fibers. Various fiber-reinforced cement products can be used in straight alignment without the fibers being eroded by the basicity of calcium hydroxide in the cement, and without gradually losing their inherent excellent mechanical properties over time. This invention is an excellent fiber-reinforced cement product that combines the excellent shading strength of aromatic polyamide fibers with the permanent physical properties such as the excellent impact resistance of polyolefin or/and polyamide fibers. has high industrial utility value. The present invention will be explained below with reference to Examples. In the examples, the bending strength was measured for boards,
JIS-A-1408, according to the bending test method for architectural boards, test using a No. 3 test piece and convert the cross-sectional area to kg/
Shown in ^cm2 . In addition, in the case of concrete, JIS-
40× according to A-1106 concrete bending test method
Tested on a 40x200mm test piece and converted to cross-sectional area.
Expressed in kg/ ^cm2 . Impact tests are conducted using JIS for boards.
The test was carried out in accordance with the asbestos slate test of A-5403. Alkali solubility, which is a measure of alkali resistance, strength after alkali treatment, and retention of Young's modulus were measured under the conditions and method described above. The ηinh (logarithmic viscosity) of the linearly coordinating aromatic polyamide is a value measured by a conventional method at 25° C. for a solution of 0.2 g of polymer dissolved in 100 ml of concentrated sulfuric acid. The physical properties of linearly coordinated aromatic polyamide fibers are values measured as single fibers. with gauge length
Tensile tests were performed at a tensile rate of 10% elongation/min.
This is an average of the measured values for 10 different single fibers. In addition, amounts added, percentages, etc. in the examples are values expressed in weight and weight % unless otherwise specified. Example 1 Terephthalic acid chloride and paraphenylene diamine were polymerized by a conventional method in a mixed solvent of N-methylpyrrolidone and dimethylacetamide in which lithium chloride was dissolved to produce polyparaphenylene terephthalamide (abbreviated as PPTA) with ηinh5.0. was manufactured. This polymer was dissolved in 99.5% concentrated sulfuric acid to obtain a dope containing 18% polymer. After degassing this dope under reduced pressure, it is extruded through a spinneret with 500 pores of 0.06 mm diameter into a 10 mm space, then introduced into a water coagulation solution at a temperature of 0°C, and then pulled out from the solution and washed with water on a Nelson roll. , drying continuously
Produced PPTA fiber. This fiber has a single yarn fineness of 3.1
Denier, tensile strength 290Kg/mm ² , Young's modulus 6.5×
10 ³ Kg/mm ² , an alkali solubility of 0.43%, and a strength retention rate of 96% after alkali treatment. 40 parts of this fiber cut to a fiber length of 10 mm and 110 parts of polypropylene fiber (abbreviated as PP) with a single fiber fineness of 20 denier and a fiber length of 15 mm were added together to 1900 parts of Portland cement powder and stirred and dispersed. A mortar was prepared by adding 720 times more water, which was placed in a wooden mold and molded under a pressure of 250 g/cm ² . After air curing for 24 hours, the mold was removed and left to stand. Also, in the same way, the single yarn fineness is 20 denier and the fiber length is 15.
A sample was prepared by putting 6 nylon fibers (abbreviated as 6-N) into cement powder together with PPTA fibers. The thickness of each of these samples was 8 mm. A test piece was cut out according to JIS-A-1408, and the bending strength and impact strength were measured 28 days later. The results are shown in Table 1.

[Table] Example 2 PP fiber with single yarn fineness of 25 denier and fiber length of 25 mm
For 150 parts, 100 PPTA fibers with different single yarn finenesses and fiber lengths were manufactured in the same manner as in Example 1.
2,000 parts of cement and 1,400 parts of water were thoroughly mixed and dispersed in mortar. The mortar was placed in a wooden mold and molded under a pressure of 200 g/ ^cm3 . After curing in air for 24 hours, the mold was removed and left to stand. A sample with a thickness of 8 mm was obtained. A test piece was cut out from this sample in accordance with JIS-A-1408, and its bending and impact strengths were measured after 28 days. The results are shown in Table 2.

【table】

[Table] In Table 2, Experiment Nos. 1 to 5 are examples of the present invention in which the single fiber fineness of the PPTA fibers was changed, and Nos. 6 to 10 are examples of the present invention in which the fiber length was changed, and Nos. 11 to 14 are comparative examples. Example 3 A copolyamide with ηinh of 5.5 was produced by polymerizing equimolar terephthalic acid chloride with a mixture of paraphenylene diamine and orthotolidine in a molar ratio of 85:15 in N-methylpyrrolidone containing calcium chloride. . This copolyamide was dissolved in 99.2% concentrated sulfuric acid.
An optically anisotropic dope containing 20% polymer was prepared, extruded through a metering pump into a 5 mm space through a spinneret with 200 pores of 0.05 mm diameter, and then placed in a 30% dilute sulfuric acid coagulation bath at a temperature of 5°C. After the fibers were introduced into the bath, the fibers were pulled out from the bath at various speeds to achieve a predetermined single yarn fineness, and fibers with different single yarn finenesses were wound onto a bobbin. Next, the bobbin was left in running water all day and night to wash the fibers, and then dried in a hot air dryer at 100°C. The thus obtained fibers were introduced into a metal tube placed under a nitrogen stream maintained at a temperature of 350°C and subjected to drawing heat treatment for a residence time of 10 seconds to produce the copolyamide fibers shown in Table 3. .

[Table] These heat-treated copolyamide fibers A to D are cut into fiber lengths of 25 mm and mixed with single fibers or 66 nylon (abbreviated as 66N) with different fiber lengths and/or PP fibers at a mixing ratio of 2. : Mixed so that it becomes 1
Pour 155 parts into 1900 parts of cement powder and stir.
920 parts of water was added to prepare a mortar, which was placed in a wooden mold and molded under a pressure of 200 g/cm ³ . After curing in the air for 24 hours, the mold was removed and left to obtain a sample with a thickness of 8 mm. A test piece was cut out from this sample in accordance with JIS-A-1408, and its bending strength and impact strength were measured after 28 days.
The results are shown in Table 4.

[Table] The PPTA fiber of Example 1 with a single filament fineness of 3.1 denier was cut into a fiber length of 14 mm, and 6 nylon (abbreviated as 6N) fiber with a single filament fineness of 60 denier and a fiber length of 30 mm was used to make PPTA. Mortar was prepared under the same conditions with various mixing ratios of 6N and 6N. That is, PPTA
110 parts of fiber mixed with 6N and 2000 parts of cement
Pour into a slurry made of 750 times as much water, mix and disperse thoroughly to create mortar, transfer to a wooden mold and weigh 200g/
After curing in air for 24 hours under pressure of ^cm3 , the mold was demolded and then
The sample was cured for 3 hours in steam at 100°C and then left in the air for 2 days to obtain a sample with a thickness of 8 mm. A test piece was cut out from this sample according to JIS-A-1048, and its bending strength and impact strength were measured. The results are shown in Table 5.

[Table] Example 5 Type T-956 (single yarn fineness 1.5 denier) and Type T-968 (single yarn fineness 1.42 denier) of Kevlar (said to be polyparaphenylene terephthalamide fiber) manufactured by Dupont. long fibers,
Single yarn fineness of 70 denier and 66 filament are aligned at a mixing ratio of 1.8:1 and 10 mm at the same time.
and cut into fiber length of 30 mm. 150 parts of each mixed fiber was poured into a cement slurry consisting of 100 parts of cement, 1900 parts of Toyoura standard sand, and 700 parts of water, thoroughly stirred and dispersed, then poured into a wooden mold, and after 24 hours of air curing, the mold was removed. A sample was prepared by installing the JIS-A-1106 bending strength after 28 days for each sample
The impact strength was measured on a sample with a thickness of 8 mm according to the method of JIS-A-5403. The results are shown in Table 6.

【table】 [Brief explanation of the drawing]

The drawing shows a model of the bending stress-strain curve of fiber-reinforced cement, where A is cement reinforced only with linearly coordinated aromatic polyamide fibers, and B is cement reinforced only with polyolefin or/and polyamide fibers. , C shows the bending stress-strain curve of the fiber-reinforced cement according to the present invention.

Claims (1)

[Scope of Claims] 1. A linearly coordinated aromatic polyamide fiber with a single yarn fineness of 1 to 10 denier and a fiber length of 3 to 50 mm, and a single yarn fineness of 3
Polyolefin or/and polyamide synthetic fibers of ~100 denier and fiber length of 3 to 50 mm are simultaneously mixed into cement at a weight ratio of the aromatic polyamide fibers to other fibers in the range of 3:1 to 1:8. A method for producing a fiber-reinforced cement product, characterized in that it is used in combination. 2. The linearly coordinating aromatic polyamide is polyparaphenylene terephthalamide, polyparabenzamide, or a copolyamide in which up to 20 mol% of their repeating units are substituted with other linearly coordinating aromatic polyamide. Method 3 for producing a fiber-reinforced cement product according to claim 1, characterized in that the linearly coordinated aromatic polyamide fiber has a tensile strength of 250 Kg/mm ² or more and a tensile modulus of 5.0×10 ³ Kg/
The method for producing a fiber-reinforced cement product according to claim 1 or 2, which has mechanical properties of mm ² or more.