JPH11255544A - Reinforcing fiber for cement material and formed cement produced by using the fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber resistant to autoclave treatment and having excellent adhesivity to cement matrix by using a polypropylene as the core material, of a reinforcing fiber composed of a core material and a surface layer material and using a thermoplastic polymer material having polar functional group and produced by addition polymerization as the surface layer material. SOLUTION: The thermoplastic polymer material having a polar functional group such as carboxyl group is preferably an acid-modified polypropylene, more preferably a polypropylene modified with maleic anhydride. Inorganic fine particles are added to the surface layer material. In a reinforcing fiber composed of a core material, a surface layer material and an intermediate layer material, it is preferable to use polypropylene as the core material, a thermoplastic polymer material as the surface layer material and an acid-modified polypropylene as the intermediate layer material. The addition amount of the reinforced fiber is preferably 0.3-5 wt.% and the product is preferably cured in an autoclave. Preferably, the acid-modified polypropylene has a melting point lower than that of the core polypropylene by >=5 deg.C and has an acid value of >=5. A formed cement article having high flexural strength is produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing fiber for cementitious materials which exhibits excellent adhesiveness to a cement matrix and, in particular, exhibits remarkable adhesive strength by autoclaving, and a cement molding reinforced by blending the fiber. It is about the body.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers or glass fibers of polyvinyl alcohol type, polyolefin type, polyacrylonitrile type, polyamide type, etc. have been used as reinforcing fibers for cement moldings in place of asbestos which has been pointed out as harmful. I have. However, in recent years, the curing of cement moldings has been increasing in autoclaves for the purpose of improving dimensional stability and shortening the curing time, and when performing such autoclave curing, non-polyolefin fibers are resistant to heat and alkali. However, it could not be used as a reinforcing fiber because it was deteriorated due to the shortage.

[0003] On the other hand, polyolefin fibers, which are the only general-purpose resins having heat-resistant alkali resistance, have very little hydrophilic groups or functional groups effective for adhesion to cement in their molecular structure, and therefore have extremely poor adhesion to the cement matrix. Bad, when the cement molded body reinforced with polyolefin fiber is broken, the fiber is easily pulled out, and even if increase in impact strength or bending fracture energy due to fiber pullout resistance is recognized, it is necessary to greatly improve the bending strength. There were drawbacks that could not be reached.

[0004]

To overcome the disadvantages of the prior art, various methods have been proposed for improving the affinity of polyolefin fibers with cement. As a typical method, various inorganic fine particles or a method of adding a hydrophilic polymer substance such as polyvinyl acetate to the fiber, a silane coupling agent, a surfactant or a metal salt on the surface by various methods or A method of improving the affinity by adhering and fixing has been proposed, but in the former, the foreign matter is mixed into the entire fiber, so that the stretchability is impaired, sufficient fiber strength is not obtained, and the fiber surface Other than a certain modifier, it does not contribute to the improvement of affinity, and there is a drawback that the modifying effect is not good for the added amount, and the latter has no adhesiveness between the surface treatment agent and the polyolefin fiber, so cement Even if the matrix and the surface treatment agent adhere, there is a defect that a sufficient adhesive force cannot be obtained between the fiber and the matrix.

In order to compensate for these drawbacks, the fiber has a core-sheath structure, and an ordinary polyolefin resin is used for the core material.
There has been proposed a method of blending various materials for improving affinity with a surface material. For example, Japanese Patent Application Laid-Open No. Sho 57-129861 discloses that a core material and a surface material are made of polyolefin resin,
A method has been proposed in which inorganic particles are added to the surface layer to increase the affinity. However, in this method, a polyolefin resin is used as a main material of the surface layer material, and there is a problem in adhesion between the inorganic fine particles and the polyolefin resin. Also, Japanese Patent Application Laid-Open No.
4741 and JP-A-6-9254 propose a method in which a thermoplastic resin is used for both the core material and the surface layer, and various inorganic fine particles are added to or adhere to the surface layer to enhance the affinity. However, in these methods, if a polyolefin resin is used as a core material in consideration of autoclave curing resistance, it is necessary to use a polyolefin resin as a main material of a surface material in order to prevent separation from the core material, and inorganic fine particles and polyolefin resin are also required. The adhesiveness of the resin becomes a problem.

Further, Japanese Patent Application Laid-Open No. 9-255391 discloses that a reinforcing fiber in which a high melting point resin is blended in a core material and a low melting point resin is blended in a surface layer material is mixed with a cement matrix and then cured by autoclave and molded. Methods have been proposed to strengthen the cement molding by fusing the contact points. However, in this method, if a polyolefin resin is used as a fiber material in order to impart autoclave resistance, adhesion between the fiber and the cement matrix cannot be expected. A high reinforcing effect cannot be obtained because the amount is small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it has an autoclave resistance and an excellent adhesion to a cement matrix, and a reinforcing fiber for cement-based materials. An object is to provide a cement molded body to be used.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to a reinforcing fiber for a cementitious material comprising a core material and a surface material, wherein the core material is polypropylene, and the surface material has a polar functional group and is obtained by addition polymerization. It is a reinforcing fiber for a cementitious material characterized by containing. In a preferred embodiment of the reinforcing fiber for cement-based material of the present invention, the thermoplastic polymer substance is an acid-modified polypropylene, more preferably an acrylic acid-modified polypropylene or a maleic anhydride-modified polypropylene, and inorganic fine particles are added to the surface material. It is characterized by having.

The present invention also relates to a reinforcing fiber for a cementitious material comprising a core material, a surface material and an intermediate layer material therebetween, wherein the core material is polypropylene and the surface material is a thermoplastic polymer material. And a reinforcing fiber for cementitious materials, wherein the intermediate layer material is an acid-modified polypropylene. In a preferred embodiment of the reinforcing fiber for a cement-based material according to the present invention, the acid-modified polypropylene is acrylic acid-modified polypropylene or maleic anhydride-modified polypropylene, and inorganic fine particles are added to the surface material.

[0010] The present invention is also a fiber-reinforced cement molding characterized in that 0.3 to 5% by weight of the reinforcing fiber for cement-based material is added. In a preferred embodiment of the fiber-reinforced cement molded article of the present invention, it is characterized in that it is autoclaved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The reinforcing fiber for a cement-based material of the present invention has a core material made of polypropylene, a surface material having a polar functional group, and containing a thermoplastic polymer substance by addition polymerization. The thermoplastic polymer material having a polar functional group used in the present invention and obtained by addition polymerization includes a hydroxyl group,
Carboxyl group, carbonyl group, alkoxyl group, alkoxycarbonyl group, having a polar functional group such as a glycidyl group in the molecular structure, and may be a polymer substance having thermoplasticity, for example, polyvinyl alcohol, polyvinyl phenol, polyether , Homopolymers such as carboxyl vinyl polymer, polyvinyl acetate, polyvinyl ether, acrylic resin, polyhydroxy polyolefin, and copolymers such as ethylene-vinyl alcohol copolymer and ethylene-vinyl acetate copolymer, and acrylic acid-modified polypropylene, maleic anhydride Acid-modified products of polypropylene, such as acid-modified polypropylene, may be mentioned.
In the present invention, an acid-modified polypropylene such as an acrylic acid-modified polypropylene containing a carboxyl group having excellent adhesion to polypropylene and having an excellent affinity for cement, and a maleic anhydride-modified polypropylene are preferable. More preferred.

The acid-modified polypropylene used for the surface layer of the reinforcing fiber for cementitious materials of the present invention preferably has a melting point lower than that of the polypropylene used for the core by 5 ° C. or more and an acid value of 5 or more. The reinforcing fiber for a cementitious material of the present invention is cured at a temperature lower than the melting point of the polypropylene of the core material and higher than the melting point of the acid-modified polypropylene of the surface material, and the surface material without affecting the physical properties of the core material of the polypropylene. The maximum reinforcement effect is exhibited by fusion bonding with the cement matrix, but the difference in melting point between the core material and polypropylene is 5%.
When an acid-modified polypropylene having a temperature of less than 0 ° C. is used for the surface material, it is difficult to set the temperature of the autoclave curing to a temperature that does not affect the physical properties of the core material, and a sufficient reinforcing effect cannot be obtained. Further, those having an acid value of less than 5 cannot obtain a sufficient adhesive force with the cement matrix even if the melting point is sufficiently low, and the reinforcing effect is low.

[0013] Materials such as materials other than the acid-modified products of polypropylene, which have poor adhesion to polypropylene and which may cause peeling between the core material and polypropylene when used alone for the surface material, include the surface material and the core material. When acid-modified polypropylene such as acrylic acid-modified polypropylene or maleic anhydride-modified polypropylene, which has adhesive properties to both polypropylene, is used between the surface layer and the core as the intermediate layer, or the intermediate layer is omitted. Is preferably mixed with a compatibilizer such as an ethylene-ethyl acrylate copolymer, an acrylic acid-modified polypropylene, or a maleic anhydride-modified polypropylene, and used as a surface layer material. When a resin obtained by condensation polymerization by a dehydration reaction, such as a polyester-based or polyamide-based resin, is used instead of the resin obtained by the addition polymerization in the present invention, the resin can be stored in a high-temperature high-pressure steam such as an autoclave curing atmosphere. Exposure over time may result in hydrolysis.

The reinforcing fiber for a cementitious material of the present invention is a composite fiber comprising a core material and a surface material formed of the above-mentioned materials, and the weight ratio of the core material to the surface material is 50:50 to 95: 5. Those between are preferred. This ratio is 50 to 50
If it is smaller, the ratio of the core material having strength is reduced even though the adhesive strength is obtained, and sufficient fiber strength cannot be obtained.
On the other hand, if the ratio is greater than 95: 5, it is difficult to form a surface layer without unevenness, and sufficient adhesive strength cannot be obtained.

As a method for producing the reinforcing fiber for cementitious materials of the present invention, a conventionally known production method can be appropriately used. For example, a filament having a core-sheath structure co-extruded from a nozzle is drawn, or a core material is produced. A production method such as splitting a multilayer structure film having a surface material disposed on one or both sides after stretching can be used.

The inorganic fine particles added to the surface material of the reinforcing fiber for cementitious materials of the present invention include calcium carbonate,
Talc, silica, aluminum hydroxide, sepiolite,
Examples thereof include those having excellent reactivity with cement such as mica and acid value titanium, and the particle diameter is preferably 0.01 mm or less, more preferably 0.005 mm or less. If the particle diameter is larger than 0.01 mm, the adhesiveness of the surface layer material to the resin and the reactivity with the cement are poor, so that it is not effective.

The amount of the reinforcing fiber for the cement-based material used in the fiber-reinforced cement molding of the present invention is preferably 0.3 to 5% by weight, more preferably 0.5 to 2% by weight. If the amount is less than 0.3% by weight, it is difficult to obtain a sufficient reinforcing effect. If the amount is more than 5% by weight, fiber balls are generated, so that a sufficient reinforcing effect cannot be obtained.

The reinforcing fiber for a cementitious material of the present invention has a polar functional group and is covered with a surface layer material containing a thermoplastic polymer obtained by addition polymerization. It has excellent resistance and does not easily pull out. Moreover, since polypropylene having high heat-resistant alkali properties is used for the core material, the fiber strength is not significantly reduced by the autoclave curing, and the bending strength of the cement molded product can be greatly improved.
Further, by using an acid-modified polypropylene resin for the surface layer material, a fusion bonding effect can be obtained by the heat of the autoclave curing, so that a higher reinforcing effect can be obtained.

[0019]

EXAMPLES The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m) was used as a core material by a multilayer inflation extruder.
in), 10% by weight of a crosslinked polyethylene oxide resin (manufactured by Sumitomo Seika Co., Ltd., AquaCork TQU-5), 88% by weight of the same polypropylene resin as the core material, a compatibilizer (ethylene-ethyl acrylate copolymer) ) At 2% by weight
Three-layered tubular film (layer thickness ratio 1: 8:
1, a film thickness of 0.18 mm), stretched 17 times in the machine direction using a hot-air stretching device, split using a garment roller, and then cut to a total length of 6 mm to obtain a reinforcing fiber.

100 parts by weight of the early-strength Portland cement, 100 parts by weight of silica powder (specific gravity 2.62 g / cm ² , specific surface area 5330 cm ² / g), perlite perlite (bulk specific gravity 0.11 g / cm ²⁾ 2 parts by weight with respect to 20 parts by weight, stirred and mixed using an omni mixer, added with 90 parts by weight of pure water, and further stirred with an omni mixer to obtain a cement mixture. .
Next, the cement mixture was immersed in a depth of 10 mm and a bottom dimension of 30 mm.
After being put into a 0 mm × 300 mm formwork and subjected to vibration molding, it was left under an environment of a temperature of 20 ° C. and a humidity of 80% for 24 hours to obtain a hardened cement. Next, this cement hardened material is 50 m wide
m, cut into a length of 125 mm, and autoclaved at 165 ° C. for 8 hours to obtain a cement molded body of Example 1.

Example 2 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m) was used as a core material by a multilayer inflation extruder.
in), acrylic acid-modified polypropylene resin (melting point 150 ° C., MFR = 20 g / 10 min, acid value 2)
A tubular film (thickness ratio 1: 8: 1, film thickness 0.18 mm) having a three-layer structure provided with the above 0) was prepared, and stretched 17 times in the longitudinal direction using a hot-air stretching device. After splitting using a roller, the fiber was cut to a total length of 6 mm to obtain a reinforcing fiber. Using this reinforcing fiber, molding and curing were performed in the same manner as in Example 1 to obtain a cement molded body of Example 2.

Example 3 The core material was made of a polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m by a multilayer inflation extruder.
in), a five-layer tubular film (layer thickness ratio 1: 1) in which an ethylene-vinyl alcohol copolymer (Soarnol DT2903 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was disposed as a surface layer material and a maleic anhydride-modified polypropylene resin was disposed as an intermediate layer material. : 1
6: 1: 1, film thickness 0.18 mm), stretched 17 times in the longitudinal direction using a hot-air stretching device, split using a garment roller, and then cut to a total length of 6 mm to obtain a reinforcing fiber. Obtained. Using this reinforcing fiber, molding and curing were performed in the same manner as in Example 1 to obtain a cement molded product of Example 3.

Example 4 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m) was used as a core material by a multilayer inflation extruder.
in), acrylic acid-modified polypropylene resin (melting point 150 ° C., MFR = 20 g / 10 min, acid value 2)
0) and calcium carbonate powder (average particle size 5 μm, addition amount 2)
0% by weight) to form a three-layered tubular film (layer thickness ratio 1: 8: 1, film thickness 0.18 mm), and stretched 17 times in the machine direction using a hot-air stretching device. Then, it was split using a needle roller and then cut to a total length of 6 mm to obtain a reinforcing fiber. Example 1 using this reinforcing fiber
In the same manner as in the above, molding and curing were performed to obtain a cement molded body of Example 4.

Example 5 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m) was used as a core material by a multilayer inflation extruder.
in), a three-layer tubular film (layer thickness ratio 1: 8: 1, film thickness 0) in which a maleic anhydride-modified polypropylene resin (melting point 145 ° C., MFR = 100 g / 10 min, acid value 40) was disposed on the surface material. .18 mm), stretched 17 times in the machine direction using a hot-air stretching device, split using a needle cloth roller, and then cut to a total length of 6 mm to obtain a reinforcing fiber. Using this reinforcing fiber, molding and curing were performed in the same manner as in Example 1 to obtain a cement molded body of Example 5.

Comparative Example 1 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 min) was produced by a single-layer inflation extruder.
And a 17-fold stretch in the machine direction using a hot-air stretching device, split using a garment roller, and then cut to a total length of 6 mm to obtain a reinforcing fiber. Was. Example 1 using this reinforcing fiber
The molding was cured in the same manner as described above to obtain a cement molded body of Comparative Example 1.

Comparative Example 2 A polypropylene resin (melting point 170 ° C., MFR = 2.5 g / 10 m) was used as a core material by a multilayer inflation extruder.
in), a tubular film having a three-layer structure in which a mixture of the same polypropylene resin as the core material and calcium carbonate powder (average particle size: 5 μm, addition amount: 20% by weight) was disposed on the surface material (layer thickness ratio 1: 8: 1) , A film thickness of 0.18 mm), and stretched 17 times in the machine direction using a hot-air stretching device.
After splitting using a cloth roller, the fiber was cut to a total length of 6 mm to obtain a reinforcing fiber. Using this reinforcing fiber, molding and curing were performed in the same manner as in Example 1 to obtain a cement molded product of Comparative Example 2.

Using the universal tensile tester (Shimadzu Corporation, Autograph AG-5000D), a three-point bending test was performed on the cement molded bodies of these Examples and Comparative Examples at a span of 100 mm and a crosshead speed of 5 mm / min. Was. Table 1 shows the test results.

[Table 1]

[0029]

As described in detail above, the reinforcing fiber for cementitious materials of the present invention has a polar functional group on the surface and contains a thermoplastic polymer obtained by addition polymerization.
It has excellent adhesion to the cement matrix and does not easily pull out. Moreover, since a polypropylene resin having high heat-resistant alkali properties is used for the core material, a decrease in fiber strength due to autoclave curing is small, and the bending strength of the cement molding can be greatly improved. In addition, the reinforcing fiber for cementitious materials of the present invention uses an acid-modified polypropylene, preferably a maleic anhydride polypropylene resin as a surface material, so that a fusion bonding effect can be obtained by the heat of autoclave curing, so that a higher reinforcing effect can be obtained. Can be In addition, by adding inorganic fine particles to the surface material of the reinforcing fiber for a cement-based material of the present invention, the adhesion to the cement matrix is further improved, and a higher reinforcing effect is obtained. In addition, the fiber-reinforced cement molded article of the present invention can obtain extremely high bending strength by being reinforced with the above-mentioned reinforcing fiber for cement-based material, as compared with a conventional cement molded article reinforced with polypropylene fiber.

Claims (7)

[Claims] 1. A reinforcing fiber for a cement-based material comprising a core material and a surface material, wherein the core material is polypropylene, the surface material has a polar functional group, and a thermoplastic polymer substance obtained by addition polymerization is used. A reinforcing fiber for cementitious materials, characterized in that it comprises: 2. The reinforcing fiber for cementitious materials according to claim 1, wherein said thermoplastic polymer substance is an acid-modified polypropylene. 3. The reinforcing fiber for cementitious materials according to claim 2, wherein said acid-modified polypropylene is maleic anhydride-modified polypropylene. 4. A reinforcing fiber for a cementitious material comprising a core material, a surface material and an intermediate material therebetween, wherein the core material is polypropylene, the surface material is a thermoplastic polymer material, A reinforcing fiber for cementitious materials, wherein the layer material is an acid-modified polypropylene. 5. The reinforcing fiber for cementitious materials according to claim 1, wherein inorganic fine particles are added to said surface layer material. 6. A fiber-reinforced cement molded product, wherein 0.3 to 5% by weight of the reinforcing fiber for cementitious material according to claim 1 is added. 7. The fiber-reinforced cement molding according to claim 6, which is subjected to autoclave curing.