JP2007284256A - Cement-reinforcing polypropylene fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene fiber for reinforcing cement which is permanently hydrophilic, is good in the dispersibility in cement and the physical bonding to cement, and gives a cement formed product of improved flexural toughness. <P>SOLUTION: The polypropylene fiber is one obtained by subjecting a polypropylene fiber comprising surface-roughened monofilaments spun from a polypropylene resin to a surface oxidation treatment and adhering 0.1 to 5 wt.% at least one compound as a surface treatment agent selected from among sulfonic acid compounds, polyol complexes, and polycarboxilic acid compounds. This fiber is prevented from deteriorating with time in its hydrophilicity imparted thereto by the surface treatment, is good in dispersibility in cement and physical bonding to cement, and can give a cement formed product excellent in flexural toughness. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polypropylene fiber for cement reinforcement excellent in reinforcing effect of concrete or mortar.

  Conventionally, cement molded products using mortar and concrete, or outer walls of buildings, inner walls of tunnels, slope slopes, etc. have been constructed, but these are relatively brittle as molded bodies, tensile strength, bending If physical properties such as proof stress, bending toughness, and impact resistance are not sufficient, there is a risk of water leakage due to cracks on the wall surface or an accidental peeling off of the outer wall. And mixing of steel fiber and polyvinyl alcohol fiber (for example, patent documents 1) is widely performed for the purpose of reinforcement of concrete. In addition, a reinforcement wire mesh is installed when bending strength and toughness are required in shotcrete.

  However, concrete mixed with steel fibers is difficult to transport and mix because the specific gravity of steel fibers is as high as 7.8. In shotcrete, steel fibers that have fallen due to splashing during spraying are stepped over. There is a high risk of injuries due to rusting, and the disadvantages such as rusting of steel fibers have been pointed out. In addition, concrete mixed with polyvinyl alcohol fibers has water absorption properties, and when the fibers are alkali and high in temperature, hydrolysis tends to occur, and slump tends to decrease significantly compared to those without fibers. In addition, inconveniences such as the need to increase the unit water amount in order to secure the slump necessary for spraying occur.

In order to solve such a problem, in recent years, there has been an attempt to use polyolefin fibers instead of steel fibers or polyvinyl alcohol fibers for reasons such as good moldability, light weight, and low cost (for example, Patent Document 2). ).
As the polyolefin-based fibers, in general, single yarns, bundled yarns, or split yarn short fibers having a fineness of 100 dt or less and a fiber length of 5 mm or less are often used. From this fiber shape, the properties of the fiber with low fineness and short length are disadvantageous in that fiber balls called fiber balls are formed and bulky and difficult to uniformly disperse in the cement. If the thickness is made thicker, the adhesiveness with the cement is inferior, and when a bending stress is applied, there is a tendency that a sufficient reinforcing effect cannot be obtained, for example, fibers are pulled out.

  In order to improve the hydrophilicity of the polyolefin resin fiber with cement, a surfactant composed of polyoxyalkylene alkylphenyl ether phosphate ester and polyoxyalkylene fatty acid ester is added to the polypropylene fiber having irregularities in the fiber cross section. A method of applying each has been proposed (for example, Patent Document 3). However, since the above-mentioned surfactant has insufficient adhesion to the polyolefin resin fiber, even if the cement matrix and the surfactant are adhered, There was a problem that sufficient adhesive strength could not be obtained between the polyolefin resin fiber and the matrix, and the bending toughness of the cement molded product was not sufficient.

In order to improve the problems of such polyolefin resin fibers, the present applicant has increased the length of a monofilament with a monofilament fineness of 200 dt or more with irregularities having a specific average flatness to the fiber cross section to a fiber length of 5 mm or more. There has been proposed a method of subjecting a cut polypropylene fiber to surface oxidation treatment such as corona discharge treatment, plasma treatment, flame plasma treatment, electron beam irradiation treatment, and ultraviolet irradiation treatment (for example, Patent Document 4).
However, in the proposed method of surface oxidation treatment, due to the change with time of the oxidation treatment effect, the treatment effect is diminished with time, and sufficient adhesion between the polyolefin resin fiber and the matrix cannot be obtained, and cement molding is performed. There was a problem that the bending toughness and bending toughness of the objects were not sufficient.

Japanese Patent Publication No. 1-40786 (1 page) JP-A-9-86984 (page 2) JP-A-11-116297 (page 2) JP 2004-168645 A (2 pages)

  The present invention has been made to solve the above-mentioned problems of the prior art, and can permanently impart hydrophilicity to polyolefin resin fibers, dispersibility with cement, and physical bonding with cement. An object of the present invention is to provide a cement-reinforced polypropylene fiber that has a good bending toughness and bending toughness of a cement molded article.

In order to technically solve the above-mentioned problems, the present invention protects an oxidized surface by subjecting a polyolefin fiber to surface oxidation treatment and coating the oxidation treatment surface with a specific surface treatment agent. Thus, the inventors have found that the above object can be achieved, and have completed the present invention.
That is, the gist of the present invention is that at least one compound selected from a sulfonic acid compound, a polyol and a polycarboxylic acid on the surface after spinning from a polypropylene resin and subjecting the fiber surface to surface oxidation treatment. Or it exists in the polypropylene fiber for cement reinforcement characterized by adhering 0.1-5 weight% of 2 or more types of mixtures.

  The polypropylene fiber for cement reinforcement of the present invention is obtained by subjecting a polypropylene fiber surface made of monofilaments of a specific single yarn fineness, which is spun from a polypropylene-based resin and having an uneven surface, to a surface treatment solution. As described above, a specific amount of at least one compound selected from the group consisting of a sulfonic acid compound, a polyol complex and a polycarboxylic acid compound is adhered to the polypropylene resin fiber to prevent deterioration of the hydrophilicity imparted to the polypropylene resin fiber by surface oxidation. In addition, it is possible to obtain a polypropylene fiber having good dispersibility with cement and physical bonding with cement, and capable of producing a cement molded product excellent in bending toughness and bending toughness of the cement molded product.

  In the present invention, the polypropylene resin used as the fiber raw material may be a polypropylene copolymer such as a propylene homopolymer, an ethylene-propylene block copolymer or a random copolymer, or a mixture thereof. Among these, a propylene homopolymer is desirable for cement reinforcement that requires high strength and heat resistance, and it is particularly desirable to select one having an isotactic pentad ratio of 0.95 or more. The melt flow rate (hereinafter abbreviated as MFR) of this polypropylene resin is selected from the range of 0.1 to 30 g / 10 min, preferably from 1 to 10 g / 10 min in terms of continuous stable productivity. Good.

  If necessary, other polyolefins may be added to the polypropylene resin in the spinning process. Other polyolefins here include polyethylene resins such as high density polyethylene, linear low density polyethylene, low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer, polybutene-1, etc. It is.

  The polypropylene fiber spun in the present invention is a short fiber obtained by cutting a relatively thick monofilament, and its production method is not particularly limited, and is circular, elliptical, atypical, etc. A manufacturing technique for extruding a filament from a continuous yarn-shaped die can be employed.

  In addition to the basic monolayer filament, a composite monofilament having a polypropylene high melting point component as a core layer and a polypropylene low melting point component as a sheath layer can also be used as the monofilament structure. In this manufacturing method, polypropylene of each layer is melt-kneaded with an extruder, and a core layer made of a high melting point component is supplied from a central discharge hole of a die in which two discharge holes are provided on substantially concentric circles. A sheath layer composed of a melting point component is extruded and coated to obtain a composite monofilament. In this case, since the substantial strength depends on the physical properties of the core layer, it is preferable to use a propylene homopolymer, isotactic polypropylene or the like as the high melting point component, while the propylene-ethylene block copolymer is used as the low melting point component. Polymers, random copolymers, syndiotactic polypropylene and the like are preferable. By using the composite monofilament thus obtained, it is possible to suppress thermal degradation of the polypropylene fiber during heat curing during concrete molding.

  Next, the monofilament is subjected to heat drawing and heat relaxation treatment, and the rigidity of the filament is increased by this heat treatment to obtain a polypropylene monofilament suitable for cement reinforcement having a small elongation. This hot stretching is carried out at a temperature below the melting point of polypropylene and above the softening point. Usually, the stretching temperature is 90 to 150 ° C., and the stretching ratio is usually 5 to 12 times, preferably 7 to 9 times. As the hot stretching method, a hot roll method, a hot plate method, an infrared irradiation method, a hot air oven method, a hot water method, or the like can be adopted.

  The tensile strength of the polypropylene filament is 5 g / dt or more, preferably 6 g / dt or more. Further, the tensile elongation is 20% or less, preferably 15% or less. If the tensile strength and tensile elongation are out of these ranges, the strength as a polypropylene fiber for cement reinforcement becomes insufficient, which is not preferable.

  The single yarn fineness of the formed polypropylene monofilament is in the range of 5 to 10,000 dt, preferably 200 to 10,000 dt, more preferably 200 to 6,500 dt. If the single yarn fineness is less than 200 dt, the fiber is too thin and the dispersion in the concrete mixture is uneven and easily becomes a fiber ball, which is problematic in terms of workability and reinforcement. On the other hand, if the single yarn fineness exceeds 10,000 dt, The contact area of the fiber with the concrete admixture is reduced, and the fiber is easily pulled out with respect to bending stress.

  Therefore, the polypropylene monofilament needs to have irregularities on the surface as the next step of spinning and hot drawing. As a result, the contact area between the fiber and the concrete can be increased, and the reinforcement effect can be enhanced by suppressing the pull-out of the fiber after the concrete is hardened. An example of a method for forming irregularities on the surface is a method of embossing a monofilament. Embossing is performed by passing an embossing roll before or after stretching the monofilament, and irregularities are continuously formed in the longitudinal direction of the monofilament.

  Here, the shape such as the length and depth of the emboss may be arbitrary, but the average flatness of the fiber cross section by crushing is in the range of 1.5 / 1 to 7/1, preferably 1.8 / 1 to 7/1. It is necessary to be. This average flatness is a numerical value showing the average ratio of width and height in the cross-sections of various shaped fibers. If the average flatness is less than 1.5 / 1, the fiber surface will be uneven. Since the shape is small, there is no difference between the smooth surface fiber and the reinforcing effect. On the other hand, when the average flatness ratio exceeds 7/1, the strength deterioration due to shaping is significant, and the fibers with the above specified fineness are dispersed in the concrete. The problem tends to be worse.

  In the above-mentioned polypropylene fiber, additives such as an antioxidant, a lubricant, an ultraviolet absorber, an antistatic agent, an inorganic filler, an organic filler, a crosslinking agent, a foaming agent, and a nucleating agent are within the scope not departing from the gist of the present invention. May be blended.

In the present invention, the polypropylene fiber surface is subjected to surface oxidation treatment, and the surface has a wet tension of 40 mN / m or more, preferably 40 to 70 mN / m. When the surface wetting tension is less than 40 mN / m, the polyolefin resin fiber cannot be sufficiently hydrophilic, and the bending strength and impact strength of the cement molded product cannot be improved.
The wetting tension is a value measured according to JISK6768 (1999).
The surface oxidation treatment is at least one treatment method selected from corona discharge treatment, plasma treatment, flame plasma treatment, electron beam irradiation treatment, and ultraviolet irradiation treatment, and corona discharge treatment and plasma treatment are preferred.

Corona discharge treatment, treatment conditions commonly used, for example, under conditions of a distance 0.2~5mm between electrode tip and the object to be treated base fabric. As the amount of processing, polypropylene fibers 1 m ² per 10w · min or more, The range is preferably 10 to 200 W · min, and more preferably 10 to 180 W · min. When the treatment amount is less than 10 W · min per 1 m ^{2 of} polypropylene fiber, the effect of the corona discharge treatment is insufficient, the wetting tension of the fiber surface cannot be within the above range, and the bending strength and impact strength of the cement molded product. Cannot be improved.

  The plasma treatment step is performed by using a single gas such as argon, helium, krypton, neon, xenon, hydrogen, nitrogen, oxygen, ozone, carbon monoxide, carbon dioxide, sulfur dioxide, or a mixed gas thereof, for example, an oxygen concentration of 5 to 15 volumes. % Of oxygen and nitrogen containing gas at a pressure close to atmospheric pressure to generate a plasma discharge by applying a voltage between the opposing electrodes, and then electrically exciting the charged particles with a plasma jet. It can be carried out by spraying the electrically mixed gas that has been removed and made electrically neutral to the surface of the plastic substrate. As the plasma treatment conditions, for example, the distance between the electrodes through which the plastic substrate to be treated passes is appropriately determined according to the thickness of the substrate, the magnitude of the applied voltage, the flow rate of the mixed gas, etc. The voltage applied between the electrodes is preferably 50 mm, preferably 2 to 30 mm, and the electric field strength when applied is preferably 1 to 40 kv / cm, and the frequency of the AC power supply at that time is 1 to 100 kHz.

  The flame plasma treatment step can be performed by blowing ionized plasma in a flame generated when natural gas or propane is burned onto the surface of the plastic substrate.

  The electron beam irradiation treatment process is performed by irradiating the surface of the plastic substrate with an electron beam generated by an electron beam accelerator. As the electron beam irradiation device, for example, a device “electro curtain” (trade name) that can irradiate a uniform electron beam in a curtain shape from a linear filament can be used.

  The ultraviolet irradiation treatment step is performed by, for example, irradiating the surface of the plastic substrate with ultraviolet rays having a wavelength of 200 to 400 mμ.

  In the present invention, after subjecting the surface of the polypropylene fiber to surface oxidation treatment, a specific amount of the following surface treatment agent is applied and adhered to the surface of the oxidation treatment for surface treatment.

The surface treatment agent used in the present invention contains at least one kind of a sulfonic acid compound, a polyol complex or a polycarboxylic acid compound as a main component, and one or more of these are used.
Examples of the sulfonic acid compounds include lignin sulfonic acid compounds, naphthalene sulfonic acid formalin condensates, melamine sulfonic acid formalin condensates, anthracene sulfonic acid formalin condensates, and aromatic amino sulfonic acid compounds.

  Examples of the polyols include neopentyl glycol, pentaerythritol, neopentyl glycol hydroxypivalate or derivatives thereof, hexanediol or pentanediol.

  Examples of polycarboxylic acid compounds include styrene-maleic anhydride copolymers and partially esterified products thereof, allyl ether-leic anhydride copolymers and derivatives thereof, vinyl ether-leic anhydride copolymers and derivatives thereof, and (branched) pentenyl. Examples include ether-leic anhydride copolymers and derivatives thereof, (meth) acrylic acid- (meth) acrylic ester copolymers and derivatives thereof.

Among these, a lignin sulfonic acid compound and a polyol complex, particularly a lignin sulfonic acid compound and a polyol complex are preferable.
Specifically, as these surface treatment agents, AE water reducing agents and high performance AE water reducing agents used for the purpose of imparting high fluidity to ready-mixed concrete, such as the AE water reducing agent of the NPO's Pozzolith series, Leo Build SP A series of high performance AE water reducing agents can be used, and these can be suitably used as the surface treating agent of the present invention.

  As a method for adhering the surface treatment agent to the polypropylene fiber, generally, a method of applying the surface treatment agent to the polypropylene fiber is performed. This coating method includes a dip coating method (immersion method) in which polypropylene fibers are immersed in a surface treatment agent solution, a spray coating method in which a surface treatment agent solution is sprayed onto polypropylene fibers, and a brush coating or roll coater. Examples include a method of applying a surface treating agent solution to polypropylene fibers using a varnish, a pad-drying method, etc. Among these, a dip coating method is preferred.

  The amount of the surface treatment agent attached to the polypropylene fibers is 0.1 to 5% by weight, preferably 0.5 to 5% by weight, based on the total fibers. If the adhesion amount is less than 0.1% by weight based on the total fiber, the polypropylene fiber will not be sufficiently hydrophilic, and the bending strength and bending toughness of the cement molded product will be insufficiently improved. The effect of imparting the property is not further improved, and therefore, the bending strength and the bending toughness of the cement molded body reach an equilibrium, and conversely, the cost increases.

  The surface-treated polypropylene fiber is cut to a predetermined length to become a cement reinforcing short fiber. The length of the short fiber is 5 to 100 mm, preferably 20 to 70 mm. If the fiber length is less than 5 mm, the cement comes off, and if it exceeds 100 mm, the dispersibility becomes poor.

  The polypropylene fiber for cement reinforcement of the present invention is used as a reinforcing fiber material blended with cement, fine aggregate, coarse aggregate, water and an appropriate amount of concrete admixture. Here, examples of the cement include hydraulic cements such as Portland cement, blast furnace cement, silica cement, fly ash cement, white Portland cement, and alumina cement, and cements such as plaster, air-hardening cement such as lime, and fine aggregates. Examples include river sand, sea sand, mountain sand, crushed sand, quartz sand, glass sand, iron sand, ash sand, and other artificial sand.Coarse aggregates include reki, gravel, crushed stone, slag, various artificial lightweight aggregates, etc. Is a typical example.

  When using the polypropylene fiber for cement reinforcement of the present invention for construction of shotcrete, this blending amount is 4 to 19 kg of polypropylene fiber per 1 m3 of a concrete mixture consisting of cement, fine aggregate, coarse aggregate, water, etc. It is important to mix and disperse 6 to 14 kg. This is because even if the blending amount of polypropylene fiber exceeds 19 kg, the fibers are not uniformly distributed in the concrete, so the bending toughness does not increase. On the other hand, if the blending amount is less than 4 kg, the rebound when spraying is large and the setting is hardened. Small post-reinforcing effect.

  In addition, as a mixing method in this case, a concrete mixture made of cement, fine aggregate, coarse aggregate, water and the like is added to form base concrete, and after mixing this base concrete, polypropylene fiber is added and mixed. The mixing time depends on the mixing amount per one time, but generally the mixing of the base concrete is 45 to 90 seconds, and the mixing of polypropylene fiber is also in the range of 45 to 90 seconds. It is said.

  In addition, in the construction of shotcrete, when the polypropylene fiber of the present invention is used in the above-mentioned blending amount, it is preferable to adjust the slump range to 8 to 21 cm. This is not preferable because if the slump is less than 8 cm, the spraying operation becomes difficult, and if it exceeds 21 cm, the rebound becomes large. It is effective that the spray nozzle for constructing shotcrete in such a slump range should be arranged at right angles to the spray surface and the distance between the nozzle and the spray surface should be 0.5 to 1.5 m. It becomes.

Example 1
(1) Manufacture of fiber Polypropylene (MFR = 4.0 g / 10 min, Tm = 163 ° C.) is charged into an extruder, spun from a circular nozzle, cooled, and then heated at a hot drawing temperature of 115 ° C. by a hot air oven drawing method. Stretching at a thermal relaxation temperature of 120 ° C and a draw ratio of 7-8 times to form monofilaments with a fineness of 4300 dt, and then changing the embossing nip pressure using an embossed roll with hard lattice pattern and a hard rubber roll, the average flatness is also different A polypropylene monofilament having irregularities on the surface was obtained. The wetting tension of the obtained monofilament surface was 32 mN / m.
As a surface oxidation treatment, the polypropylene monofilament was subjected to a corona discharge treatment at a rate of 30 W · min per 1 m ² of the polypropylene monofilament surface, and the resulting monofilament surface had a wetting tension of 45 mN / m.
Furthermore, as a surface treatment agent, this polypropylene monofilament was dipped in a treatment solution (Polylith No. 70 manufactured by NMB Co., Ltd.) consisting of a lignin sulfonic acid compound and a polyol complex, and then dried to adhere 1% by weight of the surface treatment solution. I let you. The polypropylene monofilament was cut to a fiber length of 48 mm to obtain polypropylene fibers.

(2) Evaluation test 1
About the polypropylene fiber fiber obtained above, after drying at room temperature for a predetermined time, after removing the surface treatment liquid adhering to the polypropylene fiber fiber by washing with water, the wetting tension is measured according to JISK6768 (1999). The results are shown in Table 1.
The wetting tension is a value measured according to JISK6768 (1999).

  As is apparent from Table 1, it was found that the polypropylene fiber coated with the surface treatment liquid did not decrease its wetting tension even after 1 year.

(3) Evaluation test 2
The polypropylene fiber obtained above was subjected to a fiber adhesion test by the following method, and the results are shown in Table 3. The specimen preparation method and the loading test method were in accordance with the Japan Concrete Institute “JCI-SF8 fiber adhesion test method”.
1) Fiber embedding condition Embedding length: 23.75 (mm)
Partition plate thickness: 0.5 (mm)
Fixing length: 23.75 (mm)
Fiber length: 48 (mm)

2) Materials used and compounding conditions Cement: Early strong Portland cement (density = 3.13 g / cm3)
Fine aggregate: Toyoura standard sand (surface dry density = 2.64 g / cm3)
Water: Tap water Cement ratio: 50%
Cement sand ratio: 1: 1.7
Fiber: Polypropylene fiber used was dried at room temperature for 180 days.
In addition, the curing was performed at 20 ° C. under water curing for 14 days.

  As is clear from Table 2, it was found that the polypropylene fiber coated with the surface treatment liquid had higher fiber adhesion than the polypropylene fiber not coated with the surface treatment liquid.

(4) Evaluation test 3
About the polypropylene fiber obtained above, the concrete reinforcement effect was tested by the following method, and the result is shown in Table 3.
1) Materials used and blending conditions Cement: Ordinary Portland cement (Density = 3.15g / cm3) 340kg / m3
Fine aggregate: Kisarazu mountain sand (surface dry density = 2.60 g / cm3) 894 kg / m3
Coarse aggregate: Ome crushed stone 1505 (surface dry density = 2.65g / cm3) 880kg / m3
Water: Tap water 170kg / m3
Admixture: High-performance AE water reducing agent EMB Leo Build SP8SB 4.42kg / m3
Fiber: Polypropylene fiber was blended at 0.3% by volume after being dried at room temperature for 180 days.

2) Mixing of concrete Using a forced biaxial mixer with a capacity of 100 liters, one batch of 60 liters is used. The temperature when the concrete was kneaded was about 20 ° C. Kneading method is to add coarse aggregate, fine aggregate and cement and perform kneading for 30 seconds, then add water and admixture, knead for 120 seconds, add reinforcing fiber and knead for 60 seconds. And discharge.

3) Preparation of specimens This was in accordance with the Japan Society of Civil Engineers standard "How to make specimens for strength and toughness testing of steel fiber reinforced concrete" (JSCE F552-1983). The specimens were demolded 24 hours later, and water curing was performed until the age of 28 days.

4) Test method This was in accordance with the Japan Society of Civil Engineers standard "Test method for bending strength and bending toughness of steel fiber reinforced concrete" (JSCE G552-1983).

  As is clear from Table 3, it was found that the polypropylene fiber coated with the surface treatment liquid had higher bending toughness coefficient and bending toughness than the polypropylene fiber not coated with the surface treatment liquid.

Comparative Example 1
In Example 1, the same procedure was performed except that the obtained polypropylene monofilament was not subjected to corona discharge treatment or surface treatment agent adhesion at all. The results are shown in Tables 1 to 3.

Comparative Example 2
In Example 1, it carried out similarly except not having made a surface treating agent adhere to the polypropylene monofilament obtained by corona discharge treatment. The results are shown in Tables 1 to 3.

Claims (5)

  After spinning from a polypropylene resin and subjecting the fiber surface to a surface oxidation treatment, 0.1 to 5% by weight of at least one compound selected from sulfonic acid compounds, polyols and polycarboxylic acid compounds is applied to the surface. A polypropylene fiber for cement reinforcement characterized by being adhered.   For polypropylene fibers composed of monofilaments having a single yarn fineness of 200 to 10,000 dt or more, which are spun from a polypropylene resin and have an irregularity in the range of 1.5 / 1 to 7/1 in the fiber cross section. The polypropylene fiber for cement reinforcement according to claim 1, wherein the surface is subjected to a surface oxidation treatment, and the wetting tension of the fiber surface is 40 mN / m or more.   Sulfonic acid compounds include lignin sulfonic acid compounds, naphthalene sulfonic acid formalin condensates, melamine sulfonic acid formalin condensates, anthracene sulfonic acid formalin condensates, aromatic amino sulfonic acid compounds, methane sulfonic acid compounds and benzene sulfonic acid compounds. The polypropylene fiber for cement reinforcement according to claim 1 or 2, which is at least one compound selected from compounds.   The cement reinforcement according to claim 1 or 2, wherein the polyol is at least one compound selected from neopentyl glycol, pentaerythritol, neopentyl glycol hydroxypivalate or derivatives thereof, hexanediol and pentanediol. Polypropylene fiber.   The polycarboxylic acid compound is a styrene-maleic anhydride copolymer and a partially esterified product thereof, an allyl ether-leic anhydride copolymer and a derivative thereof, a vinyl ether-leic anhydride copolymer and a derivative thereof, (branched) pentenyl ether. The cement reinforcement according to claim 1 or 2, which is at least one compound selected from a -leic anhydride copolymer and derivatives thereof, (meth) acrylic acid-(meth) acrylic acid ester copolymers and derivatives thereof. Polypropylene fiber.