JP2002275739A - Method for producing cement-reinforcing fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement reinforcing fiber having excellent affinity and dispersibility as a reinforcing fiber to be dispersed into cement in order to obtain a cement molding having improved flexural strength, improved control of propagation of crack, etc. SOLUTION: In this method for producing the cement-reinforcing fiber a synthetic fiber multifilament having 1,000-10,000 dtex total fineness is twisted at 400-2,700 twist coefficient K, provided with a surface treating agent to give a dip cord having >=5% elongation at 2 cN/dtex and >=5.5 cN/dtex strength at break, which is cut into 10-60 mm fiber length. The twist coefficient K is T×D<1/2> (T: number of twists (t/10 cm) and D: total fineness (dtex).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber for reinforcing cement, and more particularly to a fiber for cement molding which is excellent in tensile strength, bending strength, toughness, impact resistance and the like. It relates to reinforcing fibers.

[0002]

2. Description of the Related Art Heretofore, attempts have been made to blend short fibers of polyolefin, polyvinyl chloride, polyacryl, or polyamide as reinforcing materials for cement molded products.

However, these fibers do not have a sufficient affinity for cement and easily withdraw from the cement, so that the reinforcing effect has not been sufficiently satisfactory.

In general, fibers are often treated with a surface treating agent or a coupling agent in order to increase the affinity between the fibers and the cement, and an epoxy resin is further compounded for the purpose of improving the adhesion between the fibers and the cement. A method using a fibrous material (Japanese Patent Publication No. 61-25669) is disclosed. Also,
There has also been proposed a method of improving the shape of the fiber to reduce the detachment from the cement. For example, a method of preventing the detachment of the fiber by irregularly changing the cross-sectional area of the yarn in the drawing direction (Japanese Patent Publication No. Sho 58) No. 18343, JP-B-61
-301, JP-B-62-4346, JP-B-62-28106, etc.).

However, none of these techniques is sufficient. For example, the method using a coupling agent has a drawback that it is difficult to uniformly disperse the cement in cement, and irregularly changes the cross-sectional area of the yarn. The method has drawbacks such as difficulty in winding in the manufacturing process and poor productivity.
Further, a method of using a polypropylene fiber and overheating to improve the affinity to impart embossed irregularities to the surface (Japanese Patent Laid-Open No. Hei 10-265246) has been proposed. There has been a problem that the relaxation of the molecular orientation causes a decrease in strength and a sufficient reinforcing effect cannot be obtained.

[0006] In addition, vinylon fiber has a high affinity for cement and thus has a very good adhesive strength, but has a poor toughness. Therefore, there has been a problem that the fiber is cut along with cracking of the concrete under stress.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reinforcing fiber to be blended in cement for obtaining a cement molded product excellent in tensile strength, bending strength, toughness and impact resistance. Another object of the present invention is to provide a fiber having high toughness and high affinity with cement.

[0008]

Means for Solving the Problems In order to solve the above problems, a method for producing a fiber for cement reinforcement of the present invention mainly has the following constitution. That is, the total fineness is 1000-1
Twist with a twist coefficient K of 400 to 2700 is applied to a 0000 dtex synthetic fiber multifilament, and a surface treatment agent is applied to give an elongation at 2 cN / dtex of 5% or more and a breaking strength of 5.5 c.
N / dtex or more dip code
This is a method for producing a cement reinforcing fiber, which is cut into 60 mm.

Here, twist coefficient K = T × D ^1/2 , T: twist number (t / 10 cm), D: total fineness (dtex).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the multifilament composed of synthetic fibers used as the fiber for reinforcing cement of the present invention include polyamides, polyolefins, polyesters and the like which are generally used as general-purpose thermoplastic resins. However, in the fiber for reinforcing cement of the present invention, polyamide-based nylon 6 and / or nylon 66 are preferable from the viewpoint of alkali resistance and high toughness.

The total fineness of the synthetic fiber multifilament used in the present invention is 1,000 to 10,000 dtex, preferably 3
000 to 8000 dtex. Total fineness 100
When it is smaller than 0 dtex, the reinforcing effect as a fiber for reinforcing cement is insufficient, and when the total fineness exceeds 10,000 dtex, the dispersibility in cement is poor and the reinforcing effect is not sufficiently exhibited.

The synthetic fiber multifilament used in the present invention is twisted, and has a twist coefficient of 400 to 27.
Must be 00. When the twist coefficient is lower than 400, the cord has less unevenness, the adhesiveness to cement is reduced, and the cord is missing. On the other hand, when the twist coefficient is higher than 2700, a snarl is generated at the time of twisting, so that the twisting property is deteriorated and productivity is deteriorated. At this time, preferably 80
The untwisted cord and the untwisted cord are subjected to a 0-2000 twist and a top twist.

[0013] The cement reinforcing fiber thus obtained is
Unevenness is formed on the cord surface by the twisted yarn, and it has a characteristic that it does not easily come off from the cement. In addition, it has been hardened with a surface treating agent described later, has good releasability between the cement reinforcing fibers, and has an appropriate dispersibility when blended with cement.

The synthetic fiber multifilament used in the present invention needs to be provided with a surface treating agent in order to have rigidity. Without the surface treatment agent, the rigidity of the fiber is poor,
The fibers tend to be entangled in the cement to form lumps, resulting in poor dispersibility. As the surface treating agent, one or more urethane-based, acrylic-based, or epoxy-based treating agents can be selected and used. The unprocessed cord is sent to a dipping step as it is or after weaving in a slaid form. In the dipping step, a urethane-based, acrylic-based, or epoxy-based treatment agent is applied to the untreated cord as a surface treatment agent. The amount of the surface treatment agent applied to the cord is 1 to 15% by weight, preferably 2 to 10% by weight. The amount of the surface treatment agent to be applied is adjusted according to the cord configuration and the processing speed of the cord, by adjusting the liquid concentration of the surface treatment agent, the draining conditions, and the like. The cord that has passed through the dipping step is passed through a drying zone at 110 to 160 ° C. for about 30 seconds to 2 minutes in order to dry the surface treatment agent liquid. Then 180-250 ° C
To a high-temperature treatment zone, and subjected to a tension heat treatment for about 20 seconds to 2 minutes.
Get dip code of N / dtex or more.

The elongation at 2 cN / dtex of the dip code obtained in this way is 5% or more. If the elongation of the dip cord at 2 cN / dtex is less than 5%, the toughness is poor, and if the concrete is cracked, the cord will be cut and easily fall.

The breaking strength of the dip cord is 5.5.
cN / dtex or more. If the strength of the dip cord is less than 5.5 cN / dtex, the cord is liable to break and collapse.

The fiber length of the fiber for cement reinforcement of the present invention is 1
It needs to be 0 to 60 mm. If the fiber length is less than 10 mm, it tends to come off from the cement when blended with the cement, and if it exceeds 60 mm, the dispersibility becomes poor, which is not preferable. Such a fiber length can be obtained by cutting the dip cord obtained as described above to a specified length with a cutting machine.

An example of a method for obtaining a synthetic fiber multifilament as a raw material of the cement reinforcing fiber of the present invention will be described below.

The nylon chips are spun at a spinning temperature of 280-310.
After melting in the range of ° C., it is passed through a spin pack incorporating a metal non-woven filter having pores of about 15 to 50μ and spun through the die pores. 10-1 just below the base
A heating cylinder of 00 cm, preferably 15 to 50 cm long is installed,
Atmospheric temperature in the heating cylinder is set to 250 ° C. or more, preferably 28 ° C.
0 to 330 ° C.

The yarn that has passed through the heating cylinder is quenched and solidified immediately below the heating cylinder, and then an oil agent is applied. Next, the yarn is taken up by a take-up roll at 300 to 1000 m / min, preferably 450 m / min.
It is picked up at a speed of ~ 800 m / min.

The taken-up yarn is continuously sent to a drawing step without being wound up and drawn, and the taken-up yarn is taken up by a take-up roll and a yarn feed roll arranged following the take-up roll. While giving a stretch of 1-10% between
Further, an oil agent is applied. Usually about 50 before the take-up roll
% And the remainder is provided between the take-up roll and the yarn feed roll. The amount of the oil agent to be attached to the fiber is 0.4 to 2.0% by weight, preferably 0.6 to 2.0% by weight based on the wound fiber.
1.5% by weight.

Next, multi-stage stretching of two or more stages is employed for stretching, and the total stretching ratio is 3.7 to 6.5 times, usually 4.0.
Up to 6.0 times and a final stretching temperature of 230 ° C., preferably 23
Stretched at 5-250 ° C.

Subsequently, a relaxation heat treatment is performed to relax 3 to 10% between the final stretching roll and the relaxing roll disposed thereafter. Since the relaxation heat treatment is performed substantially on the final stretch roll, the temperature is 230 ° C., preferably 2 ° C.
35-250 ° C.

The cement reinforcing fiber of the present invention obtained by such a manufacturing method is blended with a hydraulic cement such as Portland cement, white Portland cement, alumina cement, or an air-hard cement such as gypsum or lime as a reinforcing fiber material. Used. The amount of fiber in the cement is
Usually 0.2 to 5% by weight based on cement solids,
Preferably it is 0.5 to 2.0% by weight. In addition, as a method of mixing the fiber for cement reinforcement into the cement, a method of dispersing the fiber in cement powder, a premix method of dispersing the fiber in a cement slurry, a spray-up method of simultaneously spraying the cement, the fiber and water, and the like. A known method can be used.

By mixing an appropriate amount of the cement reinforcing fiber of the present invention into cement, an excellent cement molded article can be obtained.

The cement mixture containing the cement reinforcing fiber of the present invention in an appropriate amount is molded according to a known molding method such as a papermaking molding method, an extrusion molding method, or an injection molding method, and is immersed in air or water at room temperature for several tens of days. It can be cured and cured into a cement molded product by a natural curing method that is allowed to stand. Uses of cement moldings manufactured using reinforcing fibers include all types of cement products, such as building wall materials, floor concrete, finishing mortar,
Waterproof concrete, roofing materials, and 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, fish reefs, seawalls, tetrapots, etc. It can be used for sleepers, benches, flower pots, etc. as various structures.

[0027]

EXAMPLES The method for measuring the physical properties of fibers according to the present invention is as follows.

The strength of the raw yarn and the treated cord was measured using a “Tensilon UTL-4L” type tensile tester (manufactured by Orientec Co., Ltd.) in accordance with JIS L 1017, 7.5.

As the evaluation of the physical properties of the cement specimen, the flexural strength was measured in accordance with JIS A 1408, and the state of suppression of crack propagation was ranked and judged. The area of the load-slip curve is defined as JC
It was measured using a briquette form based on I-SF8 (fiber adhesion test method) and determined by ranking the area of the load-slip curve. [Example 1] A nylon 6 chip was melted at a polymer temperature of 290 ° C using an extruder type spinning machine, and then melted at 20 µm.
Through a spinning pack incorporating a metal non-woven filter having pores of
Was spun out of the hole in the cap. A heating cylinder of 25 cm was installed immediately below the base, and the atmosphere temperature in the heating cylinder was controlled at 300 ° C.
The spun yarn was quenched after passing through the high-temperature heating cylinder atmosphere and then passing through a 120 cm long uniflow chimney attached immediately below the heating cylinder. In the Uniflow chimney, cold air at 20 ° C. was blown at a speed of 30 m / min.

Then, after the oil agent was applied, the yarn speed was controlled at a predetermined speed with a take-off roll and the yarn was taken out. Next, the yarn was sent to a stretching step, stretched continuously, and then subjected to a one-stage relaxation treatment. The take-up roll is not heated, the yarn feed roll is 60 ° C,
The temperature of the first-stage stretching roll was 120 ° C., the temperature of the second-stage stretching roll was 200 ° C., and the temperature of the three-stage stretching roll was 200 ° C. or higher. The relaxation roll after stretching was not heated.

The total draw ratio varies depending on the orientation of the undrawn yarn, but was 4.3 times, and the discharge rate was adjusted so that the fineness of the drawn yarn was 2520 dtex. 2520 dte by the above method
A nylon 6 multifilament having x, 306 filaments and a raw yarn strength of 8.2 cN / dtex was obtained.

Next, the nylon 6 multifilament obtained above was treated with 3 twists per 10 cm to obtain a twist coefficient of 1600.
After 5 times of twisting, the two twisted cords were combined and twisted 25 times in the direction opposite to the direction of twisting to obtain a raw cord.

The raw cord was applied with a sizing agent using a "Computertreater" dipping machine manufactured by Ritzler (USA) and subsequently heat-treated. The surface treatment agent used was a urethane-based treatment agent having a concentration of 15%, and the drainage conditions were adjusted so that the amount of adhesion was about 4% by weight. Subsequently, the film was passed through a drying zone at 120 ° C. for 30 seconds at a constant length, then passed through a heat treatment zone at 220 ° C., treated at a constant length for 60 seconds, and wound up.

The physical properties of the obtained dip cord are fineness 540.
0dtex, 2cN / dtex elongation 7.7%, cutting strength 6.6cN / dt
ex. This dip code is 3
It was cut to 0 mm.

In mixing the cutting fiber of the dip cord made of nylon 6 of the present embodiment with the cement to form a test piece, 100 parts by weight of Portland cement and 200 parts by weight of standard sand are sufficiently mixed and treated with nylon 6. 1.5 parts by weight of the cutting fiber of the cord was added, mixed by stirring, and further 65 parts by weight of water was added, and the whole was kneaded so as to be uniform. When checking the shape of the fiber in this state,
It was in a state of being uniformly dispersed in the cement mixture without any breakage of the cord.

For the measurement of flexural strength, this cement mixture was poured into a mold and cured in the air at room temperature for 28 days to obtain a plate having a thickness of 5 mm and a length and width of 500 mm. Similarly, a briquette form sample was prepared for the measurement of fiber pullout toughness. Table 1 shows the evaluation results.

[0037]

[Table 1] ★ [Example 2] The same as that employed in Example 1 except that the ejection amount was adjusted so that the fineness of the drawn yarn was 1000 dtex, and the original yarn strength was 8.2 cN by fine adjustment of the drawing ratio.
/ Dtex nylon 6 multifilament was obtained. The multifilament thus obtained and the multifilament obtained in Example 1 were each subjected to 35 twists per 10 cm, and then two twisted cords were combined and 25 twists in the opposite direction to the twist. The raw cord was obtained by twisting.

In the same manner as in the first embodiment, a processing code was obtained by using a “computer treater” dipping machine. The physical properties of the resulting treated cord were 3780 dtex fineness, 2 cN / dtex elongation 7.5%, and cutting strength 6.8 cN / dtex. This treated cord was cut into 30 mm by a cutting machine to prepare a cement specimen. The evaluation results are also shown in Table 1. Comparative Example 1 A cement specimen was produced in the same manner as in Example 1 except that the cutting length of the treatment cord in Example 1 was cut to 7.5 mm. The evaluation results are also shown in Table 1. Comparative Example 2 A cement sample was prepared in the same manner as in Example 1 except that the cutting length of the treatment cord in Example 1 was cut to 80 mm. The evaluation results are also shown in Table 1. Comparative Example 3 The number of twists of the twisted cord in Example 1 was 1
The same procedure as in Example 1 was carried out except that after twisting 5 times per 0 cm, the two twisted cords were combined and twisted 3.5 times in the opposite direction to the twisting to obtain a raw cord. Specimens were prepared. The evaluation results are also shown in Table 1. Comparative Example 4 The number of twists of the twisted cord in Example 1 was 1
A cement specimen was prepared in the same manner as in Example 1 except that after twisting 80 times per 0 cm, the two twisted cords were combined and twisted 55 times in the opposite direction to the twisting to obtain a raw cord. Was prepared. The evaluation results are also shown in Table 1. [Comparative Example 5] A 30 mm cut product having a single fineness of 4400 dtex, an elongation of 2 cN / dtex of 3.2%, and a cutting strength of 7.6 cN / dte, which is a vinylon generally used for a cement reinforcing fiber, was used. In the same manner as in Example 1, vinylon cutting fiber was blended with 1.5 weight cement to prepare a cement specimen. The evaluation results are also shown in Table 1.

[0039]

The fiber for reinforcing cement obtained by the present invention is formed by forming irregularities on the cord surface by twisting, applying a surface treatment agent, and curing by heat treatment, and has good dispersibility in cement. It has a structure that does not easily pull out of the thread from the cement slurry. In addition to the improvement in the bending strength of the concrete, the effect of suppressing propagation at the time of cracking is provided, the pullout toughness is high, and the cement reinforcement can be improved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D02G 3/26 D02G 3/26 3/36 3/36 D06M 15/564 D06M 15/564 F term (reference) 4L033 AC11 CA50 4L036 MA06 MA35 PA21 PA26 RA24 UA25

Claims (2)

[Claims] 1. A synthetic fiber multifilament having a total fineness of 1,000 to 10,000 dtex and a twist coefficient K of 400 to 270.
Twist of 0, applying a surface treatment agent to make a dip cord with elongation at 2 cN / dtex of 5% or more and breaking strength of 5.5 cN / dtex or more, and cut this into a fiber length of 10 to 60 mm. A method for producing a fiber for cement reinforcement, characterized in that: Here, twist coefficient K = T × D ^1/2 , T: twist number (t / 10 cm),
D: Total fineness (dtex) 2. Synthetic fiber multifilament is nylon 6
2. The method for producing cement-reinforcement fiber according to claim 1, wherein the fiber is nylon 66.