JPH03150241A - Carbon fiber for use in cement - Google Patents

Abstract

PURPOSE:To obtain the title carbon fiber improved in both compatibility and adhesivity by treating carbon fiber with a silane coupling agent followed by coating with a surfactant. CONSTITUTION:Firstly, a precursor consisting mainly of e.g. polyacrylonitrile is baked into carbon fiber >=3t/mm<2> in elastic modulus and >=50kg/mm<2> in tensile strength. This carbon fiber is then treated, if needed, through e.g. air oxidation and immersed in an aqueous solution of a silane coupling agent such as a gamma-glycidoxypropyltrimethoxysilane of the formula (X is hydrolyzable group bound to Si atom like Cl or OCH3; YR is organic functional group reactive or capable of interacting with surfactant, e.g. CH2=CH-) so as to effect 0.1-10wt.% in the pickup of the coupling agent. The resultant fiber is then further immersed in an aqueous solution of a surfactant such as a polyethylene oxide compound so as to effect 50-100wt.% in the pickup of the surfactant, thus obtaining the objective carbon fiber.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to the use of carbon fibers that have excellent uniform blendability and adhesion between carbon fibers and carbon fibers, and that exhibit good strength development when made into cement-based composite materials. This is what we provide.

[Conventional technology]

Conventionally, kneaded products using hydraulic powder of cements have been widely used in various building materials and civil engineering materials. In order to reinforce such interfering materials and prevent cracks from occurring, fibrous materials have also been blended. However, the use of asbestos as the reinforcing fiber is undesirable from the viewpoint of carcinogenicity, and since glass fiber has poor alkali resistance, it has the disadvantage that the strength of the glass fiber itself deteriorates in cement. Various organic fibers or alkali-resistant glass are being considered as reinforcing materials, but organic fibers have problems with fire resistance, and even when used as alkali-resistant glass, they cannot be used in alkaline environments such as cement. There is a problem that the strength decreases when used for a long period of time. Carbon fiber is attracting attention because of its excellent heat resistance and chemical resistance. However, when carbon fibers are added to cement and mixed, they are not uniformly dispersed. When vigorous stirring is performed to achieve even more uniform dispersion, the moment the #1 fiber breaks, a pile of fiber fluff called a fiber pole forms. Therefore, it could not be sufficiently effective as a reinforcing material.

In order to solve this problem, a method of attaching a surfactant to the fiber reinforcing material (4? 1982-96554), a method of sulfonating carbon fiber (41 1987-1378),
60), Method of mixing water reducing agent into cement (Japanese Patent Application Laid-open No. 6
1-236646), Method of Coating Carbon with IIIMK Latex C% Kaisho, 62-108755
No.), method of mixing alkali metal or alkaline earth metal chloride (JP-A No. 1-141852), method of mixing sulfuric acid or thiosulfate (JP-A No. 1-141855)
No.) etc. have been proposed.

[Problem to be solved by the invention]

However, the sulfonation treatment of carbon fibers requires a long time, and the method of attaching various compounds to carbon fibers or the method of mixing compounds into cement is difficult. There was a problem in that the ability to improve adhesion was poor because the fiber and its compound did not react.

In view of the above conventional problems, the present invention provides a carbon fiber that efficiently and effectively solves the uniform dispersibility of carbon fibers and cement and the adhesion between carbon fibers and cement.

[Means to solve the problem]

That is, the gist of the present invention is carbon fiber for cement, which is obtained by treating carbon fiber with a y-lan coupling agent and then adhering a surfactant to the carbon fiber.

The carbon fiber of the present invention is polyacrylonitrile (hereinafter PAN).
) or a precursor whose main component is pitch, with an elastic modulus of 5 t/wm" or more and a strength of 50-/
■2 or more carbon **).

Preferably elastic modulus of 20 t/m” or more and strength of 100 kf
/sw” or more carbon fiber.

The v-lan coupling agent of the present invention is represented by the following general formula (1) and must react with the surfactant to be attached later or strongly interact with the surfactant. .

Y R8i x3++++++ (1) Here, X is a hydrolyzable group bonded to a silicon atom, and Cmu0 Q Hse OQ! H S e oc, [4
oCH*eO(!OOH,.M(CFIs)s, etc.).

Here, YR is an organic functional group that reacts with a surfactant, and L/-h is an organic functional group that strongly interacts with it, and CH, = OR-, O
H = Q c H2C00-e a H, -c HOH
,O-.

Specific examples of the compound represented by the general formula (11) include T-GlyV)PquinpropyltrimethoxyVVran, r-chloropropyltrimethoxySVran, r-mercagutoglobiltrimethoxy515/ran, and r-aminopropyltrimethoxy515/ran. ! Examples include propyltriethoxyyran.

From the viewpoints of ease of use and price, r-glycidophyllintrimethoxyran is preferred.1. In.

The surfactant of the present invention is an air-entraining admixture that increases the workability of cement by entraining air into the slurry.
) K Used alkylbenzene sulfonate, triethanol alkyl sulfonate, etc., or a dispersant that facilitates dispersion of cement particles in water l Refers to a higher alcohol or sodium alkyl benzene sulfonate type.

Preferably, a polyethylene oxide compound, a**, is selected in view of its reactivity with the silane coupling agent,
Preferred examples include polyoxyethylene stearate and sodium lignin sulfonate.

The y-run coupling agent of the present invention reacts with hydroxyl groups on the surface of carbon fibers to firmly bond to carbon fibers. Furthermore, this y
The run coupling agent reacts or strongly interacts with at least a portion of the surfactant to be attached later, so that the carbon 1/111m surface is coated with the outermost MK surfactant.

The surface of carbon fibers that have not been oxidized usually has few hydroxyl groups, but depending on the method of firing carbon fibers (for example, by lowering the firing temperature), it is possible to produce carbon fibers with many hydroxyl groups. can. However, PAH-based carbon fibers are usually burned out at temperatures above 1000°C, so
There are few hydroxyl groups on the surface of F, and it is easier to react with the y-lan coupling agent by performing oxidation treatment to introduce oxygen functional groups onto the surface.

The oxidation treatment of carbon fibers can be carried out by air oxidation treatment methods, ozone oxidation treatment methods, electrolytic oxidation treatment methods, etc., which are generally applied to carbon fibers used in composite materials having a resin matrix.

The silane coupling agent is preferably attached in an amount of a1 to 10 Wt in order to react with the surface of the carbon fiber. More preferably, α5 to 5wt4 is attached. - The surfactant used in the method and dispersant can be attached to carbon fibers in an amount of 50wt or more without any problem.
It is preferable to deposit 50 to 100 wt.

The cement targeted by the carbon fibers of the present invention is hydraulic cement such as Portland cement, white Holtland cement, and alumina cement.

〔Example〕

The present invention will be specifically explained below using examples.

Example 1 Tensile strength 550 kg7wm", tensile modulus 24t
/Shin 2 non-sized carbon fibers were immersed in an aqueous solution of r-glytokiVpropyltrimethoxyran 1wt4.

Thereafter, it was heat-treated at 150° C. for 5 minutes, and the carbon fibers treated with a y-lan coupling agent were immersed in a 10 wt 1 aqueous solution of an ethylene oxide adduct of bisphenol as a surfactant for adhesion treatment.

This carbon fiber was cut into a length of 6cm, and water/cement/
The mixture was added to a kneaded product with a weight ratio of methyl cellulose 100150/[15] and mixed. This mixture was cast into a SOXSO- mold. Curing was done in water at 20°C for 1 day and at 50°C in water for 2 days.
I went for days.

This sample was cut into 4×15α pieces and subjected to a bending test. The bending strength was 180 kg/ext''.

Example 2 Table 1 shows the physical properties when molded under the same conditions as Example 1 except for the conditions shown in Table 1.

Table 11 y5 > ′:j! J″″ Agent Surfactant Bending Strength Comparative Example 1 Table 2 shows the physical properties of a composite material made by pressing in the same manner as in Example 1 except for the conditions shown in Table 2.

Table 2 1ajalftJ&]lsLJ-lkLi&
L, j 8: "No 1 oxidation treatment Jll
ypropyl trim ethylene oxide 12゜methoxy 5/
5/ 5n oxide adduct r1-=pu 〒“艷i!
=”-one? ]-No No 130
[Effect] The present invention greatly improves the bending strength of a molded product when mixed with cement by appropriately processing carbon fibers, and can be used as building materials such as wall materials, asbestos-cement substitute materials, structural materials, etc. Demonstrates excellent performance as a civil engineering material.

Claims (1)

[Claims] 1. Carbon fiber for cement, which is obtained by treating carbon fiber with a silane coupling agent and then adhering a surfactant. 2. The carbon fiber according to claim 1, wherein the silane coupling agent is γ-glycidoxypropyltrimethoxysilane. 3.Claim 1, wherein the surfactant is a dispersant or an AE agent.
Carbon fiber as described. 4. The carbon fiber according to claim 1 or 3, wherein the surfactant is a polyethylene oxide compound. 5. The carbon fiber according to claim 1 or 5, wherein the surfactant is a sulfate. 6. The carbon fiber according to claim 1, wherein the carbon fiber to be treated is an oxidized carbon fiber.