JP3517330B2 - Polypropylene fiber for cement reinforcement - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement reinforcing polypropylene fiber for reinforcing a cement molded product. 2. Description of the Related Art It has been widely attempted to mix short fibers obtained by cutting synthetic resin fibers in place of asbestos which has been used as a reinforcing material for cement molded products for many years. Conventionally, it has been thought that a fiber having a high tensile strength simply as a fiber for cement reinforcement improves the strength of a cement molded body, but improves affinity at an interface between a fiber surface and cement and prevents interface separation. It has also been known that improving the dispersibility of fibers and cement contributes to the improvement of impact strength and bending strength of a cement molded product. As a specific means for that purpose, it is effective to impart appropriate entanglement and convergence to the short fibers during kneading the cement, but if the convergence is too strong, the fibers harden and dispersibility in the cement becomes insufficient. If the convergence is insufficient, there is a problem that the rigidity of the fiber is not obtained and the strength of the cement molded product is not sufficient. It is also known that when the short fibers are hydrophobic, a floating type phenomenon occurs in which the short fibers float in the cement slurry. However, good sedimentation is achieved by imparting hydrophilicity to the short fibers. It has been well known that the properties of the fibers are improved, the dispersibility is further improved, and a predetermined fiber reinforcing effect is obtained by homogeneously mixing the fiber and the cement. However, when polypropylene fiber is used as the synthetic resin fiber, the polypropylene fiber has insufficient affinity with cement and the shape of the short fiber is simple, so that the fiber easily escapes against stress and the reinforcing effect is not sufficient. In addition, polypropylene fibers are hydrophobic, and there is a problem that a floating phenomenon occurs during kneading of cement and sufficient dispersibility cannot be obtained. In order to solve these problems and further improve the entanglement and bunching of short fibers, surface treatment is performed with various surfactants and the like, but a satisfactory surface treatment agent has not yet been obtained. [0003] The present invention solves the phenomenon of floating during kneading with cement by imparting hydrophilicity to polypropylene fibers and imparting appropriate convergence. An object of the present invention is to provide a polypropylene fiber for cement reinforcement that improves the impact strength and bending strength of a cement. [0004] In order to solve the above problems, the present invention uses a specific surfactant as a surface treatment agent in a specific blend with polypropylene fibers. Reached. That is, it comprises a polyoxyalkylene alkylphenyl ether phosphate (A) and a polyoxyalkylene fatty acid ester (B),
The gist is a polypropylene fiber for cement reinforcement in which a fiber treatment agent having a weight ratio of (A) / (B) of 60/40 to 40/60 is attached to 0.1 to 10% by weight based on the total fiber. DETAILED DESCRIPTION OF THE INVENTION The polyoxyalkylene alkyl phenyl ether phosphate (A) used in the present invention can be represented by the following general formula (1). Here, R1 in the formula is an alkyl-substituted phenyl group, and the alkyl group usually has 8 to 12 carbon atoms. R2 is an ethylene group or a 1,2-propylene group, preferably an ethylene group. X is a monoester and x is a diester. [0006] Specific examples of the polyoxyalkylene alkyl phenyl ether phosphate (A) include polyoxyethylene nonyl phenyl ether phosphate,
And polyoxyethylene dodecylphenyl ether phosphate. The polyoxyalkylene fatty acid ester (B) used in the present invention can be represented by the following general formula (2). Here, R3 in the formula is an alkyl group or an allyl group having 12 to 20 carbon atoms, preferably 16 to 20 carbon atoms.
18 alkyl groups or allyl groups. [0009] Specific examples of the polyoxyalkylene fatty acid ester (B) include polyoxyethylene oleate and polyoxyethylene stearate. The above polyoxyalkylene alkyl phenyl ether phosphate (A) and polyoxyalkylene fatty acid ester (B) preferably have an HLB value of 8 to 14 determined by the following equation. ## EQU1 ## [0013] In the above range of HLB value, the molecular weight of polyethylene glycol is appropriately adjusted, so that it has excellent affinity for resin and also excellent hydrophilicity. In the present invention, a polyoxyalkylene alkyl phenyl ether phosphate (A) and a polyoxyalkylene fatty acid ester (B) are mixed and used as a surface treatment agent for polypropylene fibers. The weight ratio of (A) and (B) used is (A) / (B) is 60.
It is important that the ratio be between / 40 and 40/60. That is,
If the weight ratio of (A) / (B) is out of this range, the polypropylene fiber treated in the cement slurry causes a floating phenomenon, and dispersibility deteriorates. The amount of the surface treatment agent attached to the fibers is as follows:
0.1 to 10% by weight based on the total fiber, preferably 1 to 10%
5% by weight. 0.1% by weight based on total fiber
If it is less than 10%, the hydrophilicity is not sufficiently imparted to the polypropylene fibers, and if it exceeds 10% by weight, the convergence of the polypropylene fibers becomes strong, and the dispersibility in the cement slurry is poor. The polypropylene forming the fibrous body used in the present invention may be a known polypropylene copolymer such as a propylene homopolymer, an ethylene-propylene block copolymer or a random copolymer, or a mixture thereof. Can be, but among these high strength,
For cement reinforcement requiring heat resistance, propylene homopolymer is desirable, and it is particularly desirable to select one having an isotactic pentad ratio of 0.95 or more. Here, the isotactic pentad fraction is defined as A. Zambelli
Et al., Macromolecules 6 925 (1973), which means the isotactic fraction in pentad units within a polypropylene molecule measured using 13C-NMR. The above polypropylene has a melt flow rate (hereinafter abbreviated as MFR) of 0.1 to 50 g / 10 mi.
n, preferably 1 to 40 g / 10 min., and more preferably 5 to 30 g / 10 min. The above-mentioned polypropylene may have an antioxidant, a lubricant, an ultraviolet absorber, an antistatic agent, an inorganic filler, an organic filler, a cross-linking agent, a foaming agent within a range not departing from the gist of the present invention depending on the purpose of use. An additive such as a nucleating agent may be blended. The method for producing polypropylene fibers is as follows:
Known melt spinning methods can be adopted, and the fiber form is not limited. For example, a split fiber obtained by splitting a polypropylene film (Japanese Patent Publication No. 5-87460, Japanese Patent Application Laid-Open No. 4-59644), a multifilament having a low fineness, or the cross-sectional area of a spun yarn irregularly with respect to the drawing direction. What was changed (Japanese Patent Publication No. 58-18343)
And Japanese Patent Publication No. Sho 62-28106), and a fiber in which a filament is spun using a continuous yarn-shaped die capable of a high-magnification drawing process and the filaments are separably connected. It is said that these polypropylene fibers preferably have a tensile strength of 4 g / d or more for the reinforcing effect of cement. Further, it is considered that a single yarn fineness in the range of 2 to 70 d is suitable from the viewpoint of dispersibility in cement, that is, 2 d
If it is less than 70 d, the fibers are too fine and the dispersion becomes non-uniform. The polypropylene fiber is treated using the above-mentioned surface treating agent. Before the surface treatment, a corona treatment or the like may be performed as necessary. After a predetermined amount of the surface treating agent is attached, the bundle is collected, dried and cut into a predetermined length. The fiber length to be cut is preferably 3 to 30 mm, more preferably 5 to 15 mm. If the fiber length is less than 3 mm, detachment from the cement occurs, and if it exceeds 30 mm, the dispersibility becomes poor, which is not preferable. Examples of the cement into which the polypropylene fiber of the present invention can be mixed include hydraulic cements such as Portland cement, white Portland cement and alumina cement, and cements such as air-hard cements such as gypsum and lime. The blending amount of the polypropylene fibers is generally 0.1 to 10% by weight based on the cement. For example, 0.2-0.5% by weight in siding,
1 to 1.5% by weight is blended in the tile. The method of mixing the polypropylene fiber of the present invention with cement includes the method of dispersing polypropylene fiber in cement powder, the premix method of dispersing polypropylene fiber in cement slurry, and the simultaneous spraying of cement, polypropylene fiber and water. A known method such as a spray-up method can be used. The cement slurry obtained by these methods is molded according to a known molding method such as a paper forming method, an extrusion molding method, an injection molding method, or the like according to the application, and is left in the air or water at room temperature for several tens days, or a natural curing method. 2-3 After standing at normal temperature 100
Cured and cured by an autoclave curing method, which is treated at a temperature of ~ 200 ° C, to obtain a cement molded product. The cement molded article produced by using the polypropylene fiber of the present invention can be used for all kinds of cement products. For example, it is used for building wall materials, flooring concrete, finishing mortar, waterproof concrete,
Roofing materials or civil engineering related materials include pavements such as roads and runways, road signs, road members such as gutters, pipes such as sewer pipes and cable ducts, fishing reefs, seawalls, tetrapots, etc. , Bench, flower pot, etc. Examples Test method (1) Flexural strength: JIS-A1408 compliant (2) Charpy impact strength: JIS-B7722 (3) Fiber floating ratio evaluation: A cement slurry is prepared by kneading polypropylene fiber and cement. After standing for 30 minutes, the floating polypropylene fiber was calculated with respect to the input amount. (4) Evaluation of dispersibility: A polypropylene slurry and a cement were kneaded to prepare a cement slurry, and the state of the surface was visually evaluated. EXAMPLE A mixture of 50% by weight of polyoxyethylene nonylphenyl ether phosphate (HLB = 8.0) and 50% by weight of polyoxyethylene oleate (HLB = 9.0) was mixed with an aqueous solution of a surface treating agent. Created. Polypropylene (MFR = 1.0 g / 10 min.) Is supplied to an extruder,
Extruded from a continuous yarn nozzle with 0.6 mmφ × 25 holes,
After cooling, the film was stretched at a stretch ratio of 12 times. The single yarn fineness of the obtained drawn yarn was 25d. The drawn yarn was immersed in the previously prepared aqueous solution of the surface treatment agent, dried, and cut so that the average fiber length became 6 mm, to obtain a polypropylene fiber of the example. FIG. 1 shows a partial cross section of this fiber. The single filament 2 is connected at a connecting portion 3 and this connection is made by an external force such as kneading during cement mixing.
It has a configuration that can be separated into about five continuous yarns. The molding of the cement molding using this polypropylene fiber was carried out according to JIS-R5201. That is, 100 parts by weight of Portland cement and 200 parts by weight of standard sand are sufficiently mixed, 5 parts by weight of the above composition is added, and 65 parts by weight of water are added and kneaded so that the whole becomes uniform, and then 40 mm × 40 mm × After pouring into a 160 mm mold and leaving it to stand in the air at room temperature for 48 hours, it was cured in an autoclave at 165 ° C. for 20 hours. The obtained molded product had a bending strength of 190 kg / cm 2, a Charpy impact strength of 6.5 kg-cm / cm 2, and a fiber floating ratio of 0.
% And the fiber dispersibility was good. COMPARATIVE EXAMPLE 1 70% by weight of polyoxyethylene nonyl phenyl ether phosphate (HLB = 8.0) and 30% by weight of polyoxyethylene oleate (HLB = 9.0) were mixed to form an aqueous solution of a surface treating agent. Was prepared, and the others were described in Example 1.
In the same manner as in the above, a cement molded product was molded. The bending strength of the obtained molded product was 165 kg / cm 2, the Charpy impact strength was 3.5 kg-cm / cm 2, the fiber floating ratio was 20%, and the fiber dispersibility was poor. COMPARATIVE EXAMPLE 2 30% by weight of polyoxyethylene nonyl phenyl ether phosphate (HLB = 8.0) and 70% by weight of polyoxyethylene oleate (HLB = 9.0) were mixed to obtain an aqueous solution of a surface treating agent. Was prepared, and the others were described in Example 1.
In the same manner as in the above, a cement molded product was molded. The bending strength of the obtained molded product was 175 kg / cm 2, the Charpy impact strength was 2.8 kg-cm / cm 2, the fiber floating ratio was 16%, and the dispersibility of the fiber was slightly poor. The polypropylene fiber for cement reinforcement of the present invention has reached the present invention by using a specific surfactant as a surface treatment agent in a specific blend with respect to the polypropylene fiber. That is, by using the polyoxyalkylene alkylphenyl ether phosphate (A) and the polyoxyalkylene fatty acid ester (B) at a specific weight ratio, the polypropylene fiber is given hydrophilicity and moderate convergence, Manufacture of cement molded products with excellent bending strength and impact strength because it prevents the floating phenomenon of polypropylene fibers when preparing a cement slurry and can impart excellent affinity at the interface between polypropylene fibers and cement for proper convergence. Can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view showing a polypropylene fiber of the present embodiment. [Explanation of Signs] 1 Polypropylene fiber 2 Single filament 3 Connecting part

Claims (1)

(57) [Claim 1] It comprises a polyoxyalkylene alkylphenyl ether phosphate (A) and a polyoxyalkylene fatty acid ester (B), and the weight ratio of (A) / (B) is 60. A polypropylene fiber for cement reinforcement obtained by adhering 0.1 to 10% by weight of a fiber treating agent of / 40 to 40/60 to the total fiber.