JPH0114189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to cement reinforcing fibers, particularly to cement reinforcing fibers that have excellent adhesion to cement. Conventional technology Hydraulic raw materials such as cement and gypsum are used to finish ceilings, walls, and floors, and to manufacture concrete blocks, cement tiles, pavement stones, etc., but as is well known, cement molded products are Because of their poor bending strength, tensile strength, and impact strength, these cement products are reinforced with fibers or the like in order to make more effective use of them. Asbestos is a typical reinforcing material for fibers, but in recent years steel fibers, glass fibers, polypropylene fibers, polyamide fibers, polyvinyl alcohol fibers, aramid fibers, etc. have been used singly or in combination. When using asbestos, the reinforcing effect is relatively large even at an addition rate of 15 to 35%, but asbestos is suspected to be a carcinogen and poses a hygiene problem.
Glass fiber is corroded by the strong alkalinity of cement, so it has poor durability as a reinforcing material. On the other hand, polypropylene fiber, polyamide fiber,
Polyvinyl alcohol fibers, aramid fibers, and the like do not have sufficient adhesion to cement, which is a matrix, and their reinforcing effects as reinforcing materials are limited. The properties required for cement reinforcing materials are high Young's modulus, high strength, alkali resistance, and high interfacial bonding strength with the cement matrix. In other words, no matter how high Young's modulus and high strength reinforcing material is used, unless the adhesiveness at the interface between the reinforcing material and the cement matrix is good, a high reinforcing effect cannot be expected. Therefore, as a result of intensive research to develop reinforcing fibers that have high adhesion to cement matrix, the present inventors succeeded in developing cement reinforcing fibers that have extremely high adhesion to cement matrix, and have thus achieved the present invention. This is what I did. Structure of the Invention In other words, the present invention provides: ``(1) Elements selected from the group consisting of elements belonging to Group or the 3rd period, 4th period, 5th period of Group, or 4th period of Group in the Periodic Table of the Elements. A cement reinforcing fiber (2) comprising an oxide of one or more elements attached to the fiber surface with a water-soluble adhesive; The fiber for reinforcing cement according to claim 1 (3) The fiber for reinforcing cement according to claim 1 or 2, wherein the fiber is an aromatic polyamide. Here, the elements belonging to the 3rd period, 4th period, and 5th period of the group in the periodic table of elements are aluminum, gallium, indium, etc. Elements that belong to this group include silicon, titanium, and tin. Elements belonging to the fourth period of the group include cobalt, nickel, and the like. The oxide of one or more elements selected from these element groups is not limited in the number of bonded oxygens as long as it is an oxide. The fibers can be asbestos, steel fibers, glass fibers, polypropylene fibers, polyamide fibers, polyvinyl alcohol fibers, aramid fibers, or fibers made of a combination thereof, but fibers that have a high Young's modulus, high strength, and alkali resistance can be used. Preferably, aramid fibers are used as the fibers. In particular, aromatic polyamide fibers consisting of the following repeating units (1) to (4) have particularly excellent alkali resistance among aramid fibers, and are therefore most preferred as fibers for use in the present invention. [In the formula, Ar ₁ , Ar ₂ , and Ar ₃ may be the same or different, and are aromatic carbocyclic residues in which the bonding chains extend coaxially or in parallel axes; represents aromatic heterocyclic residues and combinations thereof that must be bonded accordingly.
Ar ₄ and Ar ₅ may be the same or different and are selected from paraphenylene groups and metaphenylene groups. ] The relationship between the number of moles of repeating units is essentially (1) + (2) +
When (3) + (4) = 100 mol%, (3) is 0 to 90 mol%,
(4) is a fiber comprising a polymer having a content of 5 to 50 mol%, preferably 10 to 30 mol%. Aromatic carbocyclic residues with bond chains extending coaxially are, for example, 1,
4-phenylene, 1,4-naphthylene, etc., and aromatic carbocyclic residues with bond chains extending in the parallel axis direction include, for example, 1,5-naphthylene, 2,
6-Naphthylene, etc. Examples of the alkyl group having 5 or less carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, etc., and a methyl group is preferable. A substituent may be bonded to the carbon atom of the above aromatic carbocyclic residue and aromatic heterocyclic residue. Such substituents include halogen groups (e.g., chlorine, bromine, fluorine), lower alkyl groups (e.g., methyl, ethyl, isopropyl, n-propyl groups), lower alkoxy groups (e.g., methoxy, ethoxy groups),
Examples include cyano group, acetyl group, and nitro group, with chlorine group and methyl group being preferred. The fiber surface is coated with an oxide of one or more elements selected from the group consisting of elements belonging to Group 3, 4, 5, or 4 of Group 4 in the Periodic Table of the Elements. The following methods can be used for adhering to the surface. The simplest method is to apply the oxide powder to the yarn immediately after spinning without solidifying it, or to apply the oxide dispersion to the yarn after spinning. However, there are problems with this method, such as the oxide powder causing yarn breakage, fuzz, etc. during the spinning process after spinning, and the oxide easily separating from the fibers, making it impossible to obtain the expected effect. Not. In the present invention, cement reinforcing fibers having the oxide on the surface were obtained by the following method. First, the surface of the fiber is degreased in the usual manner. Next, a water-soluble adhesive having an epoxy group, for example, is added to an aqueous solution of an alkoxide such as aluminum, zirconium, titanium, silicon, etc., and then an acid is added to hydrolyze the alkoxide. The obtained aqueous solution is applied to the spun fibers according to a conventionally known method such as a spray method, a coating method, or a dipping method, and heat treatment is performed. As a result, the oxide of the gel-like polymer is applied and fixed to the fiber surface together with a water-soluble adhesive having an epoxy group. The fineness of the fiber used here is preferably in the range of 0.5 to 3 deniers as a single yarn fineness, particularly 1.5 to 3 deniers.
A range of 3 denier is preferred. If the single yarn fineness is less than 0.5 denier, fluff and single yarn breakage are likely to occur during the spinning process, which is not preferable. If it exceeds 3 deniers, the state of dispersion in concrete will deteriorate, so it is necessary to consider the form of textiles or net-like materials. Effects of the Invention As a result of the structure described in detail above, the cement molded product reinforced with the cement reinforcing fiber of the present invention is significantly superior in bending strength and tensile strength to conventional products. EXAMPLES The present invention will be specifically explained below using examples. Example 1 A copolymer obtained by copolycondensing 25 mol% of paraphenylene diamine, 50 mol% of terephthalic acid chloride, and 25 mol% of 3,4'-diaminodiphenyl ether was wet-spun by a conventional method. Then, it was stretched to 1500 denier at a temperature of 500℃ and a stretching ratio of 10 times.
A fully aromatic polyamide fiber of 1000 filaments was obtained. The fiber is made of zirconium pentoxide; Zr
(OC ₅ H ₁₁ ) ₄ , silicon ethoxide; Si(OC ₂ H ₅ ) ₄
A mixed aqueous solution of Zr (OC ₅ H ₁₁ ) ₄ /
Polyamine epichlorohydrin (trade name: Polyfix; manufactured by Showa Kobunshi Co., Ltd.) having one epoxy group on Si (OC ₂ H ₅ ) ₄ = 30/70) was added at a ratio of 20% by volume to the mixed aqueous solution, Furthermore, 5% by volume of 1% by weight acetic acid aqueous solution was added to the solution, and the mixture was thoroughly stirred. Next, the above fully aromatic polyamide fibers were immersed in the mixed aqueous solution, and then heated at a temperature of 500°C.
The heat treatment was carried out for a treatment time of 5 minutes. As a result, a fiber having a uniform coating layer containing zirconium, silicon, and polyamine epichlorohydrin on its surface was obtained (hereinafter referred to as fiber A). The amount of zirconium pentoxide, silicon ethoxide, and polyamine epichlorohydrin deposited on the fiber surface was 4.5% by weight. Next, using a forced squeezing mixer, 200 kg of Portland cement (manufactured by Mitsubishi Mining Cement Co., Ltd.) was mixed with 400 kg of fine stone (river sand) with a particle size of 3 mm or less and 400 kg of rough lubricant (crushed stone) with a particle size of 30 mm or less.
After mixing 100 kg of water and 0.5 kg of a reducing agent (manufactured by Pozolis Bussan Co., Ltd.), the mixture was stirred uniformly. At this time, dry mixing takes about 40 seconds and wet mixing takes about 80 seconds.
After a few seconds, the previously obtained surface-coated wholly aromatic polyamide fiber A (cut length, 12 mm) was gradually added to a volume ratio of 20%, and kneading was continued until uniformly mixed. Specimens for bending tests (prismatic; 10 cm x 10 cm x 40 cm) and tensile test specimens (cylindrical; diameter 10 cm x height 20 cm) were made from the mixed concrete and placed in an atmosphere with a temperature of 20°C and a relative humidity of 80% RH. After curing for 24 hours in an atmosphere of 20° C. and relative humidity of 65% RH for 7 days. The bending strength and tensile strength of the obtained specimens were measured using an Amsler bending tester and an Instron tensile tester, respectively. The evaluation results are shown in Table 1. Note that the comparative example is a case of concrete produced under the same conditions as the example except that there is no fiber reinforcement. 【table】

Claims (1)

[Claims] 1 1 selected from the group consisting of elements belonging to Group 3, 4th period, 5th period, or 4th period of Group in the Periodic Table of Elements
A water-soluble adhesive is added to an aqueous solution of oxides of the above elements, and then hydrolyzed, the resulting solution is adhered to fibers, and then heat treated at high temperatures to form a uniform oxide coating layer on the fiber surface. A method for producing fibers for reinforcing cement.