JPH06104584B2 - Fiber material for cement reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a reinforcing carbon fiber used in a carbon fiber reinforced cement material.

(Prior Art) In recent years, carbon fiber reinforced cement materials have received attention as a material having heat resistance, fire resistance, water resistance, lightweight and high strength, and are being actively used for construction, civil engineering, etc. is there.

By the way, since carbon fiber is inferior in adhesiveness (or adhesiveness) to cement as compared to asbestos and glass fiber which have been conventionally used for cement reinforcement, the adhesiveness has been conventionally improved to obtain a carbon fiber reinforced cement. Various measures have been taken to increase the strength of the material. For example, a method of tensioning a carbon warfare strand impregnated with a hydrophobic liquid resin such as an epoxy resin in cement to simultaneously cure the resin and the cement (Japanese Patent Publication No. 58-19620). Bound to each other with a water-soluble binder such as methyl cellulose. Of arranging the above-mentioned carbon fibers in the cement in one direction or in two intersecting directions (JP-A-56-129657) Magnesia cement mixed with an inorganic cement surface-treated with an organic chelating agent (JP-A-57-56363) ) A method of stacking cement slurry layers through a carbon fiber sheet containing a water-soluble synthetic resin emulsion such as acrylic emulsion (Japanese Patent Laid-Open No. 58-223659) Fiber surface when manufacturing a reinforced cement material by the Hachiekku papermaking method A method of adhering a nonionic or cationic polymer flocculant such as polyalkylaminoacrylate to the surface of the polymer (JP-A-60-81052). And the like have been attempted.

(Problems to be Solved by the Present Invention) However, in these conventional techniques, there are limitations on the form of carbon fiber used (method), and there are limitations on construction method (methods,). However, since there are inconveniences such as the target cement type being restricted and (the method of), carbon fiber that can be used without such restrictions,
It is desirable to have carbon fibers that have good adhesion to cement and can provide a high-strength reinforced cement material.

(Means for Solving Problems) The present inventors provide a carbon fiber reinforced cement material which does not have the restrictions of these conventional methods and further enhances the adhesiveness between carbon fiber and cement and thus has excellent strength. As a result of diligent research to develop a method for obtaining the same, it was found that when a mixture of carbon fiber and cationic rubber latex attached to the cement is mixed into the cement, the strength and flexibility of the obtained carbon fiber reinforced cement material are improved. The present invention has been reached.

That is, the object of the present invention is to provide a novel cement reinforcing fiber material and a reinforced cement material excellent in physical properties using the same, the object of the present invention, on the surface of the carbon fiber, This is easily achieved by a fiber material for cement reinforcement to which a cationic rubber latex selected from at least one selected from the group consisting of styrene-butadiene rubber latex, butadiene rubber latex and acrylonitrile-butadiene rubber latex is attached.

Hereinafter, the present invention will be described in detail.

The carbon fiber used in the present invention can be used without particular limitation as long as it is a known carbon fiber, for example, coal-based or petroleum-based pitch, coal liquefaction, polyacrylonitrile, cellulose, polyvinyl alcohol and the like as a raw material system. Carbon fiber can be used. Among these, carbon fibers made from pitch containing an optically anisotropic phase (so-called mesophase phase), which has been actively developed recently (hereinafter abbreviated as "mesophase pitch carbon fiber"), is carbon for cement reinforcement. Compared to carbon fiber made from isotropic phase pitch, which does not contain optically anisotropic phase, which has been mainly used as a fiber, it has higher strength and elasticity, so it is attractive for cement reinforcement. There are few examples of use.

In the present invention, it is particularly preferable to use the pitch-based carbon fiber corresponding to meso because a high-strength carbon fiber reinforced cement material can be obtained.

The mesophase pitch carbon fiber used in the present invention can be made from mesophase pitch having an optically anisotropic portion content of 30% or more, preferably 50% or more.

The content of the optically anisotropic portion of the mesophase pitch in the present invention is a value determined as the area ratio of the portion showing the optical anisotropy in the pitch under a polarization microscope at room temperature.

Specifically, for example, by crushing a mesophase pitch sample into a few mm square according to a conventional method, a sample piece is embedded in almost the entire surface of the resin having a diameter of about 2 cm, and after polishing the surface, the entire surface is cleaned. It is determined by visually observing under a polarizing microscope (100 magnification) throughout and measuring the ratio of the optically anisotropic portion due to the total surface area of the sample.

Furthermore, when the tensile elastic modulus of the mesophase pitch-based carbon fiber used in the present invention is 10 T / mm ² or more, it is preferable because a higher strength reinforced cement material can be obtained, and such a carbon fiber is a spinning pitch. It can be manufactured by appropriately selecting the content of the optically anisotropic portion, spinning conditions, carbonization or graphitization temperature, and the like.

Next, the cationic rubber latex used in the present invention is a rubber polymer, when it is produced by a method of re-emulsifying a polymer obtained by a water emulsion emulsion polymerization method or a polymer obtained by another polymerization method into a water emulsion system using an emulsifier. By using the following cationic surfactant, a so-called cationic emulsion in which the rubber polymer is positively charged is produced.

The cationic surfactant is usually an alkylamine such as polyoxyethylene tallow alkylamine, polyoxyethylene tallow alkylpropylenediamine, lauryl trimethyl ammonium chloride, lauryl dimethyl benzyl ammonium chloride, cetyl dimethyl ethyl ammonium bromide, lauryl dimethyl chloro. A quaternary ammonium salt such as benzyl ammonium chloride is used.

These cationic surfactants are usually added as an emulsifier in an amount of about 0.1 to 10% by weight based on the rubber latex.

It is also possible to use a cationic rubber latex which is produced by once producing an anionic rubber latex and then modified by adding a cationic surfactant so as to exhibit a cationic property.

As the rubber component of these cationic rubber latex, styrene-butadiene rubber latex, butadiene rubber latex, and acrylonitrile-butadiene rubber latex are preferred because of their versatility.

When a carbon fiber surface with a cationic rubber latex attached is used, the strength and flexibility of the obtained carbon fiber reinforced cement material are improved as compared with the case of using a carbon fiber without a rubber latex attached.

To infer the reason for this improvement effect, the surface of cement particles and aggregate sand particles is negatively charged, while the cationic rubber latex on the carbon fiber surface is positively charged, and an electric attractive force is generated between them. As a result, it is considered that the adhesion between the carbon fiber and the cement particles or sand particles is strengthened, and the strength of the reinforced cement material is improved. This reason is supported by the fact that the strength is not improved when the anionic rubber latex is attached. Further, the adhesion of the cationic rubber latex has the effect of increasing the elasticity of the reinforced cement material obtained and, for example, increasing the amount of deflection until the maximum bending stress is reached during a bending test. The reason for this is considered to be that elasticity is generated at the interface between the carbon fiber and the cement matrix due to the rubber elasticity of the rubber latex.

Conventionally, since carbon fiber is a highly rigid filler having no elasticity, there has been a problem that the carbon fiber reinforced cement material obtained has poor elasticity, but this problem can also be improved by the present invention.

The amount of solids in the rubber latex attached to the carbon fibers is preferably in the range of 0.1 to 10% by weight. If the adhesion amount is insufficient, the effect is not exhibited, while if it is excessively adhered, the fiber surface becomes sticky and the handling property of the fiber is deteriorated.

The amount of adhesion can be adjusted by appropriately devising the solid content (latex) concentration of the rubber latex and the method of adhesion, for example, the method of contacting with a roller or a guide and the method of immersion. Further, since the rubber latex is used in the state of the emulsion of the aqueous solution, the carbon fiber to which the latex of the aqueous solution is adhered may be usually dried to remove the water content.

The amount of adhesion can be determined by a method of quantifying the amount of rubber latex by thermal decomposition, acid decomposition, solvent extraction or the like according to the type of rubber polymer using a carbon fiber sample to which rubber latex is adhered.

For example, when styrene-butadiene rubber latex is attached, it can be obtained as the weight reduction rate at the time of thermal decomposition at 450 ° C. for 15 minutes in a nitrogen gas atmosphere.

Furthermore, as the carbon fibers that can be used in the present invention, not only fibers that have been simply carbonized or graphitized but also fibers that have been surface-treated with these carbon fibers can be used.

As the surface treatment, various methods such as oxidation treatment, etching treatment with plasma, coating treatment with various substances such as SiC, and the like, which are usually carried out as the surface treatment of carbon fiber, can be used, but the oxidation treatment is particularly preferable. The method of oxidation treatment is not particularly limited as long as it is a known method, for example,
A method of electrolytic oxidation using carbon fiber as an anode in an electrolyte solution such as an aqueous solution of caustic soda, a liquid-phase oxidation method of contacting carbon fiber with an oxidizing liquid such as concentrated nitric acid, and contacting carbon fiber with an oxidizing gas such as ozone or oxygen A vapor phase oxidation method or the like can be used.

Among them, the electrolytic oxidation treatment is advantageous in that each filament can be uniformly oxidized in a short time, and is a method having a high practicality.

And, the carbon fiber subjected to the surface treatment, particularly the oxidation treatment, to which the cationic rubber latex is adhered is preferable because it can obtain a higher strength cement material than the one not subjected to the surface treatment.

(Effects of the present invention) As described above, according to the present invention, a carbon fiber reinforced cement material having high strength and flexibility by attaching a cationic rubber latex to the surface of carbon fiber and using it for cement reinforcement is provided. Brings the effect obtained.

When the carbon fiber of the present invention is used for cement reinforcement, there is no limitation on the fiber form and construction method as in the prior art, and depending on the manufacturing method of the reinforced cement material, short fiber shape, long fiber (or strand). ), Sheet, non-woven fabric, woven fabric, etc. It has the advantage that it can be applied by various methods such as direct spray method, premix method, impregnation method (or handlay-up method), and papermaking method. Further, it can be mixed with various hydraulic cements such as Portland cement, blast furnace cement, alumina cement and calcium silicate to produce carbon fiber reinforced cement materials of various shapes such as plate, tube and column.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 Hydrogenated coal heat pits and heat-treated at 325 ° C. according to a conventional method of mesophase pits having a content of 70% optically anisotropic portion.
Melt-spin to obtain pitch fibers, infusibilize the pitch fibers at 400 ° C. in an air atmosphere, and further in an argon atmosphere at 110 ° C.
Carbonization was performed at 0 ° C. to obtain mesophase Pitch-based carbon fibers having the physical properties shown in Table 1. Then, a solid content concentration of 29%, a bound styrene amount of 65%, a cationic styrene-butadiene rubber latex (Sementex C, manufactured by Obanaya Sangyo) using an alkylamine-based cationic activator as an emulsifier was diluted with demineralized water. The aqueous solution of latex having a solid content concentration of 2% was continuously immersed in the aqueous solution in the form of long fibers and dried at about 110 ° C. to obtain carbon fiber having 2.3% by weight of rubber latex attached. .

The amount of latex attached was determined by precisely weighing 0.3 g of the sample carbon fiber and thermally decomposing it in a nitrogen gas atmosphere at 450 ° C. for 15 minutes, and the weight reduction rate was determined based on the carbon fiber.

Subsequently, after cutting the carbon fiber with rubber latex attached to a length of 10 mm, water 45, aggregate (silica sand) 50, admixture with 100 parts by weight of cement was admixed in accordance with the conventional method of the Premits method, which is a method for manufacturing reinforced cement. 2.5 Kneading in an omni mixer together with each part by weight of cement slurry to form a plate-shaped test piece, and curing in air (temperature 20 ° C, relative humidity 65
%) To obtain a carbon fiber reinforced cement material having a carbon fiber volume content of 3%. The bending property was 7 days and the values shown in Table 1. (Average value of 3 test pieces having a length of 16 cm, a width of 4 cm, and a thickness of 1.2 cm, span between 10 cm, and three-point bending test method).

Comparative Example 1 Table 1 shows the physical properties of the carbon fiber reinforced cement material obtained in the same manner as in Example 1 except that the same carbon fiber as in Example 1 was used and no rubber latex was attached.

Example 2 The same carbon fiber as in Example 1 was subjected to electrolytic oxidation treatment in an electrolyte aqueous solution (0.2% caustic soda) using the fiber as an anode, with a current density per fiber surface area of 2.9 mA / cm ² and an electrolysis time of 1 minute. After washing with water and drying, carbon fibers having the physical properties shown in Table 1 were obtained. Then, in the same manner as in Example 1, 1.3% by weight of a cationic styrene-butadiene rubber latex was attached, and then,
It was mixed with cement to obtain a carbon fiber reinforced cement material having the physical properties shown in Table 1.

Comparative Example 2 Table 1 shows the physical properties of the carbon fiber-reinforced cement material obtained in exactly the same manner as in Example 2 except that the rubber latex was not attached.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromichi Sakai 1 2447 Fujita, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Mitsubishi Kasei Kogyo Co., Ltd. Kurosaki Plant (56) References JP-A-60-81052 (JP, A) ) JP-A-59-168126 (JP, A) JP-B-60-4286 (JP, B2)

Claims (5)

[Claims] 1. Cement reinforcement obtained by adhering a cationic rubber latex selected from the group consisting of styrene-butadiene rubber latex, butadiene rubber latex and acrylonitrile-butadiene rubber latex on the surface of carbon fiber. Textile material. 2. The fiber material for cement reinforcement according to claim 1, wherein the carbon fiber is a meso-layer pitch carbon fiber. 3. The fiber material for cement reinforcement according to claim (1) or (2), wherein the carbon fiber is surface-oxidized. 4. The fiber material for cement reinforcement according to claim 1, wherein the tensile modulus of elasticity of the carbon fiber is 10 T / mm ² or more. 5. The cement reinforcing fiber according to claim 1, wherein the amount of the cationic rubber latex attached is 0.1 to 10 parts by weight as a solid content. Material.