JPS6218504B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fiber-reinforced cement molded article blended with aromatic polyetheramide copolymer fibers having excellent alkali resistance, high strength, and high Young's modulus. It is generally known to incorporate fibrous reinforcement into cement products. This is to improve cement products, which have low tensile strength and are susceptible to bending deformation. Currently, asbestos is the most commonly used cement reinforcement material, but restrictions are being placed on its handling because it can cause harm to the human body, including silicosis. Alkali-resistant glass fiber is used as a fibrous material to replace asbestos. However, its alkali resistance is still insufficient compared to asbestos, and it has the disadvantage that it cannot be cured in an autoclave, which is an efficient method for obtaining molded articles with high strength. On the other hand, there is also a lot of research into using synthetic fibers as reinforcing materials. Nylon and polyester have poor alkali resistance, while polyolefin has good alkali resistance but low tensile strength and Young's modulus.
Due to its low heat resistance, the reinforcing effect is not sufficient. Fully aromatic polyamide is known to be a fiber that has high strength, high Young's modulus, and excellent alkali resistance in addition to heat resistance and heat sintering resistance. Then, a fiber-reinforced cement molded body (Defensive
Publication USP1974.9.3), Fiber-reinforced cement products using a mixture of polymetaphenylene isophthalamide fibers and alkali-resistant glass fibers (Publication USP1974.9.3);
49-104918) Also, fiber-reinforced cement molded products using fully aromatic polyamide fibers, particularly polyparaphenylene terephthalamide fibers (Japanese Patent Application Laid-Open No. 138422), and mixtures of linearly coordinated aromatic polyamide fibers and polyolefin fibers are also available. The fiber-reinforced cement used (Japanese Unexamined Patent Publication No. 54-155222) is known. However, since polymetaphenylene isophthalamide fibers have low strength and Young's modulus, their reinforcing effect is not sufficient. Furthermore, although linearly coordinated aromatic polyamide fibers such as polyparaphenylene terephthalamide fibers have high strength and high Young's modulus, their alkali resistance is insufficient, and although they do not have sufficient reinforcing effects. do not have. The inventors of the present invention have conducted intensive research to improve these drawbacks, and as a result, we have developed fibers with excellent tensile strength, bending strength, and impact resistance using fibers with high strength, high Young's modulus, and extremely excellent alkali resistance. This led to the invention of a reinforced cement molded body. That is, the present invention is a fiber-reinforced cement molded article made by blending hot drawn fibers made of an aromatic polyetheramide copolymer with cement. The hot drawn fibers made of an aromatic polyetheramide copolymer constituting the fiber-reinforced cement molded article of the present invention preferably have the following structural units (), ()
It is composed of a copolymer consisting of and (). [In the above formula (), X is a halogen atom, n
is a number of 0 or 1, in the above formula (), Ar ₁
represents a paraphenylene group, and Ar ₂ represents a paraphenylene group or a metaphenylene group. ] Examples of such copolymers include the following copolymers. (a) Poly(paraphenylene/3,4' diphenyl ether terephthalamide) copolymer consisting of the following repeating units (A) and (B) (b) Poly(paraphenylene/4,4' diphenyl ether terephthalamide) copolymer consisting of the following repeating units (A) (B') (c) Copolymer consisting of the following repeating units (A) (A') (B) In the above copolymer, the total number of moles of the structural units () and () is substantially the same as the number of moles of the structural unit (), and the structural unit ()
When the total of () and () is 100 mol%, the structural unit () is 45 to 10 mol%, and the structural unit () is 5 mol%.
~40 mol% is preferred. Such a copolymer has the above structural unit ()()
It is obtained by reacting an aromatic diamine and an aromatic dicarboxylic acid derivative corresponding to () in a predetermined ratio. As dicarboxylic acid derivatives,
Among the dicarboxylic acid halides, it is preferable to use dicarboxylic acid chlorides. The polymer constituting the fiber used in the present invention is
Using these monomers, it can be obtained using polymerization methods commonly used in the production of polyamides, such as melt polymerization, solid phase polymerization, interfacial polymerization, and solution polymerization. Among these, the melt polymerization method is preferred. As the solvent used in the solution polymerization method, aprotic amide polar solvents such as tetramethylurea, hexamethylphosphoramide, dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide are preferred. These may be used alone or in combination. During polymerization, additives may be added before, during, and after polymerization. Such additives include various inorganic compounds, some of which are added to neutralize by-produced hydrohalides and/or to facilitate dissolution.
Examples of such inorganic compounds include lithium chloride, lithium carbonate, calcium oxide, calcium hydroxide, calcium chloride, calcium carbonate, and the like. The polymerization solution can be used as it is as a forming solution for spinning, film forming, etc., with or without the addition of these various salts. As other additives, a terminal capping agent can be used as necessary. Furthermore, various polymer additives such as light stabilizers and crosslinking agents can be added to molded products such as fibers and films to improve their properties. The polymer can be isolated by mixing the solution after the polymerization reaction and/or neutralization reaction with a precipitant such as water and washing and drying the resulting precipitate, which is then dissolved in a solvent again and used for spinning and production. It can also be used as a solution for forming films and the like. The fibers used in the present invention are obtained by filtering and defoaming the solution obtained as described above, then spinning it into an aqueous coagulating solution, washing, drying, and hot stretching. The polymer solution may be discharged into a liquid or by a so-called dry jet wet method in which it is once discharged into the air and then introduced into the liquid, with the dry jet wet method being preferred. Further, the hot stretching is preferably carried out at a temperature of 250° C. or higher and 600° C. or lower at a stretching ratio of 2 times. Linear aromatic polyamides such as Kevlar, which has high strength and high modulus, may be used as reinforcing fibers for cement products as they are spun, and the spun fibers can be heated at temperatures of, for example, 200°C or higher and generally 300°C.
It is known that the fibers can be heat-treated under tension or in a relaxed state at the above temperature to further improve strength, Young's modulus, and alkali resistance, and then used as reinforcing fibers for cement products. (JP-A-53-138422, JP-A-54-155222) However, the alkali resistance of the linear coordination fiber is inferior to that of the aromatic polyetheramide copolymer fiber used in the present invention. Linear coordination aromatic polyamide fiber has a hot drawing ratio of 200°C or higher.
Whereas the fibers used in the present invention can only be heat-treated under tension of 1.5 times or less or in a relaxed state, the fibers used in the present invention are heat-stretched at a temperature of 200°C or higher to 2 times or more, preferably 5 times or more, resulting in high strength and high elasticity. It exhibits high alkali resistance and high alkali resistance. For example, when comparing the strength retention rate (%) after 50 hours at 95°C in a saturated Portland cement solution at 100°C, polyparaphenylene terephthalamide fiber (Kevlar-29), which is a linear coordination fiber, has a strength retention rate of 35%.
%, and the fiber (Kevlar-49) which is further subjected to tension heat treatment has a fiber strength of 70%, whereas the fiber used in the present invention has a fiber strength of 95% or more.
Furthermore, when comparing the strength retention rate after 10 hours when immersed in a 10% caustic soda aqueous solution at 95℃,
The polyparaphenylene terephthalamide fiber (Kevlar-29), which is a linear coordination fiber, has a concentration of 20%, and the fiber obtained by further tension heat treatment (Kevlar-49) has a concentration of 60%. The fiber used in the invention is more than 95%. The excellent alkali resistance of the fibers used in the present invention is due to the aforementioned polymer composition of the fibers, and is due to the fact that they are hot-stretched by more than twice the amount at a temperature of 200° C. or higher. Heating methods for hot stretching include on a heating plate, on a heating pin, in a heating tube without contact, in a heated liquid, and a combination of these methods.The atmosphere around the fiber is air, nitrogen, argon, etc. An inert gas is used. The fibers used in the present invention have higher tensile strength and higher modulus than ordinary synthetic fibers, but these values are usually 180% as filaments.
Tensile strength of Kg/mm ² or more, preferably 350 Kg/mm ² , more preferably 420 Kg/mm ² , or 4×10 ³ Kg/mm 2
mm ² , preferably 6×10 ³ Kg/mm ² , more preferably 11×10 ³ Kg/mm ² . In addition, the fiber used in the present invention has a single fiber fineness of
Those of 0.5 to 15 denyl are preferred. It is preferable to use an oil agent or a surface treatment agent for the fibers as required for production and use. The fiber-reinforced cement molded article of the present invention may have any shape and may be mixed using any mixing method, and the fibers used may be in a cut state or continuous fibers. For mixing the cement slurry and the fibers, a known method such as a premix method, a direct spray method, or a spray suction method can be used. When short fibers are mixed in, the cutting length is 5 to 50 mm.
degree is preferred. When used as a continuous fiber, a filament winding method or the like is preferred. The ratio of cement slurry to fiber used in the fiber-reinforced cement molded product of the present invention varies depending on the application, but is usually based on the cement weight after hardening.
It is 0.1 to 20% by weight, preferably 1 to 8% by weight. Furthermore, it may be a fiber-reinforced cement molded product using a mixture of the fibers used in the present invention and other fibers. Other fibers include general organic fibers, inorganic fibers, and carbon fibers. Also, the mixing ratio should be selected depending on the required characteristics of the application. Furthermore, the present fiber may be used after being fibrillated. Furthermore, the fibers used in the present invention include pulp-like fibrils made of the polymer that constitutes the fibers. Pulp-like fibrids can be produced from a polymer solution by a known method. It is obtained by mixing the polymer solution in a precipitant under high shear and then overwashing. In addition, these pulpy fibrids and normal fibers,
Furthermore, it may be mixed with fibrillated fibers and used in the fiber-reinforced cement molded article of the present invention. To create a fiber-reinforced cement compact, it must be cured and cured. A commonly used method for curing fiber-reinforced cement molded bodies using glass fibers is to leave them at room temperature for several tens of days. This method does not provide high cement strength and has low production efficiency. In the autoclave curing method, the product is left at a temperature of 2 to 3 days and then cured in an autoclave at a temperature of 100 to 200°C, resulting in high production efficiency and improved strength. In the case of glass fibers, this method is rarely used because of the insufficient alkali resistance and the alkalinity of cement. The fiber-reinforced cement molded article of the present invention can be said to be suitable for autoclave curing because it uses fibers with excellent alkali resistance. As the cement, portland cement, alumina cement, high slag cement, etc. can be used. The present invention will be described in detail below with reference to Examples. Example 1 Polymerization was carried out in NMP using 25 mol% of paraphenylene diamine, 25 mol% of 3,4'-diaminodiphenyl ether, and 50 mol% of terephthalic acid chloride, and the polymer concentration was neutralized with calcium hydroxide.
A 6.0% spinning solution was prepared. Apply this solution to a pore size of 0.2 mm.
After extruding into the air through a cap with φ and 1000 holes, it was placed in an aqueous coagulation bath, washed with water, and dried. The dried fibers were stretched 11.0 times on a hot plate at 510°C, coated with oil, and wound around a winder. This fiber has a single yarn denier of 1.5 denier and a tensile strength measured as a single yarn of 430 Kg/mm ² ,
The initial modulus was 7.5×10 ³ Kg/mm ² and the specific gravity was 1.35. The short fibers are cut into 12.7mm pieces and mixed with Portland cement slurry to make a molded body.
After curing and curing for 28 days at room temperature, the tensile strength and bending strength were measured and are shown in Table 1. In Table 1, the cement weight after hardening and molding is shown as the ratio (%) of the fiber weight to the cement weight, that is, the characteristics with respect to the fiber filling ratio (%).

[Table] Comparative Example 1 Table 2 shows the measured values when polyparaphenylene terephthalamide fibers (Kevlar-29, Kevlar-49) were used in the same manner as in Example 1.

【table】

[Table] Comparative Example 2 Table 3 shows the results of measurements conducted in the same manner as in Example 1 using alkali-resistant glass (manufactured by Birkind Prathers; Semfil).

[Table] Example 2 Using the same fibers as those used in Example 1, a molded body was made in the same manner, and instead of being left at room temperature for 28 days, it was left for 10 days, and then autoclaved at 170°C for 5 hours. I went there. The results were as shown in Table 4.

[Table] Comparative Example 3 The same procedure as in Example 2 was carried out using alkali-resistant glass fiber (manufactured by Birkind Prathers; Semfil). The results are shown in Table 5.

[Table] Example 3 Polymerization in NMP using 15 mol% of paraphenylene diamine, 15 mol% of 3,4'-diaminodiphenyl ether, 20 mol% of chlorparaphenylene diamine, and 50 mol% of terephthalic acid chloride, and calcium hydroxide The solution was neutralized with water to prepare a spinning solution with a polymer concentration of 6.0%. Using this solution, spinning and stretching were carried out in exactly the same manner as in Example 1. The obtained fiber has a single yarn denier of 2.0 denier, a tensile strength of single yarn measurement of 390 Kg/mm ² and an initial modulus of 9.5×10 ³ Kg/
mm ² and specific gravity was 1.36. Using this fiber, a fiber-reinforced cement molded body was made in exactly the same manner as in Example 1, and the tensile strength and bending strength were measured. Table 6 shows the results.

[Table] Example 4 The polymer solution obtained in Example 1 was diluted with NMP to obtain a polymer solution with a polymer concentration of 3% by weight, which was poured into water under high speed stirring to obtain pulpy fibrids. . A fiber-reinforced cement molded body was obtained in the same manner as in Example 1 using the pulp-like fibrids thus obtained. The fiber filling rate was 4wt%. The resulting molded article had a tensile strength of 125 Kg/cm ² and a bending strength of 404 Kg/cm ² .

Claims (1)

[Scope of Claims] 1. A fiber-reinforced cement molded article obtained by blending hot drawn fibers made of an aromatic polyetheramide copolymer with cement. 2. The fiber-reinforced cement molded article according to claim 1, wherein the aromatic polyetheramide copolymer is a copolymer consisting of the following structural units (A), (B) and (C). [In the above formula (), X is a halogen atom, n
is a number of 0 or 1, and in the above formula (), Ar ₁ represents a paraphenylene group, and Ar ₂ represents a paraphenylene group or a metaphenylene group. ] 3. The aromatic polyamide copolymer is such that the total number of moles of the above structural units () and () is substantially equal to the number of moles of the above structural units (), and the ratio of the above structural units () is 5 to 40 mol%. The fiber-reinforced cement molded article according to claim 2, which is a copolymer of. 4. The fiber-reinforced cement molded article according to claim 1, 2, or 3, wherein the hot-drawn fibers are drawn at a stretching ratio of 2 times or more at a temperature of 250° C. or higher and 600° C. or lower. 5. A fiber-reinforced cement molded article according to claim 4, wherein the hot-drawn fibers have a tensile strength of at least 180 Kg/mm ² and a modulus of at least 4×10 ³ Kg/mm ² .