JP3166180B2 - Fiber-reinforced hydraulic molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced hydraulic molded article having high bending strength and large bending strain, that is, high strength and excellent toughness, and a method for producing the molded article. .

[0002]

2. Description of the Related Art Hitherto, asbestos has been widely used for reinforcing hydraulic materials such as cement and gypsum.

[0003] However, asbestos is a natural material, and its price fluctuates greatly. In recent years, it has become clear that asbestos dust is harmful to health and hygiene, so that its use is being avoided or restricted. Therefore, the development of a fiber material to replace asbestos is being studied on a global scale, including in Japan.

[0004] As a fiber material which has been substituted for asbestos, glass fiber, rock wool, carbon fiber,
Many fibers have been proposed, such as steel fibers, aramid, olefinic fibers, vinylon and acrylic fibers. Among these alternative fibers, acrylic fibers, which are inexpensive, have excellent alkali resistance and excellent adhesion to hydraulic substances such as cement, are attracting attention, and are beginning to be used for reinforcing materials such as siding boards, slate and roofing materials. Was.

However, acrylic fibers obtained by conventional wet spinning have low tensile strength, fail to provide a sufficient reinforcing effect as compared with asbestos, and have inferior bending strength of molded articles. Therefore, the present inventors have previously disclosed Japanese Patent Application No. 59-1258.
No. 18 (Japanese Patent Publication No. 1-40785) discloses a fiber-reinforced hydraulic material reinforced with acrylic fiber having a high knot strength, a high knot strength, and a smooth fiber surface obtained by dry-wet spinning. It was proposed to significantly increase the bending strength, bending work and impact strength of molded products.

[0006]

On the other hand, as building materials become larger or longer, the bending strength of hydraulically molded products such as cement has been increased more than before in order to prevent breakage during transportation or at construction sites. High performance with high bending strain, that is, excellent toughness has been required.

The inventors of the present invention have focused on the bending fracture behavior of a hydraulic molded product reinforced with acrylic fibers in order to impart greater toughness to a brittle substance having a small fracture elongation such as cement. As a result, the present invention has been accomplished.

[0008] That is, an object of the present invention is to provide a fiber-reinforced hydraulic molded article having acrylic fiber as a reinforcing material, having high bending strength and large bending strain, and a method for producing the same.

[0009]

The fiber-reinforced hydraulic molded product of the present invention which achieves the above object is characterized in that a molded product comprising an acrylic fiber to which a surface treating agent is adhered and a hydraulic substance is subjected to bending fracture. This is a fiber-reinforced hydraulic molded product in which at least three cracks occur on the tensile side when subjected to heat treatment.

In the method for producing a fiber-reinforced hydraulic molded article of the present invention, the method for producing a fiber-reinforced hydraulic molded article using a hydraulic substance and an acrylic fiber comprises bonding an acrylic fiber to a hydraulic substance. A method for producing a fiber-reinforced hydraulic molded product, characterized by using an acrylic fiber to which a surface treatment agent for weakening a force is adhered.

[0011]

Hereinafter, the present invention will be described in detail.

The characteristics of the fiber-reinforced molded product according to the present invention are as follows.
When a fiber-reinforced molded product (hereinafter, simply referred to as a molded product) made of an acrylic fiber and a hydraulic substance is bent and fractured, at least three, preferably four or more, more preferably five or more cracks are formed on a tensile side. Is to happen.

[0013] Originally, acrylic fibers have excellent adhesion to hydraulic materials such as cement. Therefore, when a molded article using the acrylic fibers is bent and fractured, at most one crack is formed on the tensile side, that is, the acrylic fibers are formed. Normally, one large crack is generated with cutting of the system fiber. Therefore, a molded product using such an acrylic fiber as a reinforcing material has a characteristic that bending strain is small and toughness is inferior.

Therefore, in order to increase the bending strain of a molded product, it is necessary to generate a large number of minute cracks not accompanied by fiber cutting other than one large crack accompanied by fiber cutting on the tensile side when bending and breaking. It is important. According to the findings of the present inventors, adhesion of the acrylic fiber to the hydraulic material without impairing the reinforcing effect on a hydraulic material such as cement as a matrix by applying a surface treatment agent to the acrylic fiber, according to the knowledge of the present inventors. It is important to reduce the force, and it is necessary to apply a surface treatment agent so that at least three cracks are generated on the tensile side in a bending fracture test of a molded product as described later. The upper limit of the number of cracks is not particularly limited, but according to various findings of the present inventors, about 100 to several hundreds are required in order to effectively exhibit the intended effect of the present invention. Seem to be realistic, and more realistically, up to about several tens seems to be sufficient. In other words, it seems that there is not much difference in the effect even beyond that.

The surface treatment agent to be attached to the acrylic fiber in the present invention is not particularly limited as long as it can generate at least three cracks on the tensile side when the molded article is bent and broken. For example, polyethylene oxide, polypropylene oxide, polyvinyl alcohol graft-polymerized with acrylonitrile, crosslinkable polyvinyl alcohol, water-soluble polyester, urethane resin, modified fluoro resin, amino-modified, alcohol-modified and epoxy-modified silicone resin. Among them, particularly, a polyethylene oxide compound (for example, a carboxyl group is introduced into a side chain of low molecular weight polyethylene, and a part of the compound is represented by the general formula (-C
H ₂ CH ₂ O-) _l -H compound obtained by introducing a polyoxyethylene group and the like represented by), or modified fluororesin, especially a polyfluoroalkyl group-containing compound,
Preferably, a compound containing a polyperfluoroalkyl group (for example, a polyperfluoroalkylalkenyl carboxylate resin having a structure represented by the following formula 1 as a main constituent unit, or a structure represented by the following formula 2 as a main constituent unit: And polyvinyl perfluoroalkylate resin).

[0016] Here, R1 and R1 ′ are hydrogen, a lower alkyl group, a reactive atomic group having a carboxyl group or an amino group or a hydroxyl group, R2 is a perfluoroalkyl group represented by the general formula C _n F _{(2n + 1)} , l, m and n are all integers, but the value of n in R2 must be at least 3 or more, preferably 6 or more in order to obtain sufficient performance. A suitable fluorine-free atomic group between the ester group and R2;
For _{example, (- SO 2 NR3R3'R3 "-} ) or (-CO
NH-), (-R3OCO-), (-R3O-) and (-
R3-), wherein R3, R3 'and R3 "can be introduced by appropriately combining a fluorine-free atomic group such as a lower alkyl group or a divalent alkylene group.

The copolymerization ratio of the compound containing a polyfluoroalkyl group is desirably 40% by weight or more, preferably 50% by weight or more.

When the acrylic fibers to which the above surface treatment agent is attached are blended with a hydraulic substance such as cement, they are mixed in the presence of water. In particular, a large amount of water is used when producing a molded article by a papermaking method. Therefore, it is desirable that the surface treatment agent attached to the acrylic fiber be prevented from falling off as much as possible during the production process of the molded article, that is, when the mixture is stirred in the presence of water. For example, in the case of polyethylene oxide, it is desirable to add an epoxy emulsifier or a cationic emulsifier to the aqueous emulsion or to use a high molecular weight polyethylene oxide. However, since the higher the molecular weight, the more difficult it is to uniformly adhere to the acrylic fiber, it is preferable to use one having a molecular weight of about 700 to 6000.

In the case of a modified fluoro resin, for example, in the case of a polyperfluoroalkylalkenyl carboxylate resin represented by the above formula (1) or (2), R1, R
A reactive atom group which can be introduced as a side chain into 1 'is reacted with, for example, a reactive silicone such as a silane coupling agent, a compound having an isocyanate group, or the like to prevent the reactive atom group from falling off. It is also desirable to use a silicone resin, a crosslinkable urethane resin or the like in combination as a binder.

Furthermore, in order to improve the wettability to the acrylic fiber, the polyethylene oxide is treated with a solution of polyethylene oxide in a solvent such as xylene in order to improve the wettability of the acrylic fiber in order to adhere the surface treatment agent as uniformly and widely as possible to the surface of the acrylic fiber. It is desirable to add a surface tension reducing agent to the aqueous emulsion of the surface treating agent and to treat the emulsion.

The amount of the surface treating agent is 0.05
To 2% by weight, more preferably 0.1 to 2% by weight.
5 to 1.5% by weight. Here, if the adhesion amount is less than 0.05% by weight, it is difficult to sufficiently exert the effects of the present invention, while if it exceeds 2% by weight, fibers tend to adhere to each other and the dispersibility tends to decrease. Not preferred.

Further, the method for applying the surface treatment agent is not particularly limited, and examples thereof include an immersion method, a spray method,
A touch roll method or the like can be adopted. In particular, when using a tow-shaped fiber bundle, it is effective to perform a multi-stage treatment so that the surface treatment agent is sufficiently impregnated between the fibers, use an ultrasonic wave, or heat-fix after performing the adhesion treatment. Means. The acrylic fiber used in the present invention is a fiber obtained by spinning an acrylonitrile (hereinafter abbreviated as AN) polymer in a wet, dry or dry-wet manner. Among them, in particular, the polymerization degree is obtained by spin-dry spinning a high polymerization degree AN polymer having an intrinsic viscosity of 2.5 to 5.0 and a tensile strength of at least 10 g /
d, an acrylic fiber having an elastic modulus of at least 180 g / d, a knot strength of at least 1.9 g / d, and a smooth surface is desirable. That is, when the surface treatment agent is adhered to the high-strength acrylic fiber having a smooth surface obtained by dry-wet spinning as described above, the reinforcing effect on hydraulic substances such as cement is high, and Since the adhesive strength with a hard substance can be appropriately weakened, a molded article excellent in both toughness and bending strength and excellent in toughness can be obtained.

Here, the AN-based polymer used in the production of acrylic fiber includes AN alone or at least 9%.
Monomers having copolymerizability to 0 mol% of AN and 10 mol% or less of the AN, for example, carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, and lower alkyl esters thereof, hydroxymethyl acrylate, hydroxyethyl Examples of copolymerized monomers such as acrylates, hydroxyalkyl acrylates containing hydroxyl groups of carboxylic acids such as hydroxymethyl methacrylate, acrylamide, methacrylamide, α-chloroacrylonitrile, hydroxyethylacrylic acid, allylsulfonic acid, methacrylsulfonic acid, etc. Of these, acrylamide monomers are particularly desirable for obtaining high-strength, high-modulus fibers.

These AN polymers are dimethyl sulfoxide (DMSO), dimethylformamide (DM
F), dissolved in an organic solvent such as dimethylacetamide (DMAc), a concentrated aqueous solution of an inorganic salt such as calcium chloride, zinc chloride or rhodan soda, or an inorganic solvent such as nitric acid to have a solution viscosity of 2000 poise or more, preferably 3000 to 1
A spinning solution having a 0000 poise and a polymer concentration of 5 to 20% is prepared.

From the solvent solution (spinning solution) of the above-mentioned high polymerization degree AN polymer obtained as described above, in order to produce dense fibers having as high a strength and a high elastic modulus as possible and having a small difference between the inner and outer structures, the high polymerization degree is required. A so-called dry-wet spinning method is employed in which a stock spinning solution of the AN polymer is once discharged through a spinneret into an inert atmosphere such as air, and the discharged spinning stock solution is guided into a coagulation bath to complete coagulation. It is desirable to stretch to a high degree. As a specific condition of this dry-wet spinning, the distance between the surface of the spinneret and the surface of the coagulation bath is set to 1
After discharging into a minute space formed by the spinneret surface and the coagulation bath liquid surface set within a range of from 20 to 20 mm, and preferably from 3 to 10 mm, the mixture is guided to a coagulation bath and coagulated, and then the obtained fiber yarn The thread is subjected to a post-treatment process such as washing with water, solvent removal, primary stretching, drying / densification, secondary stretching, and heat treatment by a conventional method to form a drawn fiber thread. The fiber yarn obtained by this dry-wet spinning is extremely excellent in stretchability, but is preferably at least 1.1 times, preferably 1.5 times under dry heat at 150 to 270 ° C. as a secondary drawing method. The above stretching is performed, and the total effective stretching ratio is at least 10 times, preferably 1
It is stretched so as to be twice or more, and its fineness is set in a range of 0.5 to 7 denier (d), preferably 1 to 5 d.

The obtained acrylic fiber is preferably cut to a length of 0.5 to 15 mm, and in a range of 0.1 to 5% by weight, preferably 0.5 to 3% by weight based on the weight of the composition. It is mixed with hydraulic substances.

The hydraulic substance used in the present invention refers to an inorganic substance which hardens by hydration, for example, various cements such as Portland cement, gypsum, silica stone, diatomaceous earth, blast furnace slag, fly ash and lime. Is mentioned.

Next, a mixture of the slurry or paste comprising the hydraulic substance and water and acrylic fibers mixed therein is formed into a desired shape. As a molding method, for example, a method of papermaking and molding a slurry-like compound called a Hachcheck method or a method of injecting a paste-like compound into a mold by an extruder can be applied. At this time, in order to improve the papermaking property and the fluidity of the paste, wood pulp, a pulp-like material obtained by fibrillating acrylic fibers, aramid fibers, or the like, inorganic fibers, and other fillers can be appropriately compounded. Further, pearlite, shirasu balloon, glass balloon, and the like may be appropriately blended in order to impart porosity to the molded article to reduce its weight.

[0029]

The molded article according to the present invention is made of a hydraulic substance using an acrylic fiber to which a surface treating agent is attached as a reinforcing material, and generates many cracks on the tensile side while maintaining high bending strength. It has high bending strain and excellent toughness due to bending fracture.

Therefore, it can be used for many purposes such as building materials and civil engineering materials.

[0031]

EXAMPLES Hereinafter, the effects of the present invention will be described more specifically with reference to examples. In the present invention, the measurement of the bending fracture of the molded article and the number of cracks generated on the tensile side were performed by the following methods.

Bending fracture: A test piece is prepared by cutting a molded product having a moisture content of 6 ± 1% by weight to a width of 7 mm and a length of 200 mm in parallel with the molding direction, that is, the direction in which the acrylic fibers are more oriented. . The obtained test piece was subjected to JIS-A1408.
Perform a three-point bending test perpendicular to the cut surface according to. At this time, the span is 165 mm, and the bending speed is 1 mm / min. Then, the bending strength and bending strain of the molded product are measured.

Measurement of the number of cracks: In the molded product that has been bent and fractured, cracks generated on the tensile side are observed with a magnifier having a magnification of 30 times, and the number is measured. At this time, the number of cracks is an average value when n is 7.

Examples 1 to 10, Comparative Examples 1 to 3 1% by weight of acrylamide and 99% by weight of AN were solution-polymerized in DMSO to prepare AN polymers having different intrinsic viscosities. The obtained polymer solution was used as a spinning dope and subjected to wet and dry-wet spinning. A 15 ° C., 55% aqueous solution of DMSO was used as a coagulation bath. The obtained undrawn fiber yarn is placed in a hot water bath for 5 hours.
After stretching twice, an oil agent was applied, dried at 110 ° C., and densified. Next, it was subjected to secondary drawing in a dry heat tube at 180 ° C. at a maximum draw ratio of 85% to obtain an acrylic fiber having a fineness of about 2 denier shown in Table 1.

The obtained fiber was immersed in an aqueous emulsion solution of various surface treating agents shown in Table 2, dried, and dried.
mm. At this time, the adhesion amount of the surface treatment agent is about 1
% By weight.

[0036]

[Table 1]

[0037]

[Table 2]

Next, 10 g of wood pulp, 5 fine silica powders
0 g and 410 g of Portland cement were placed in 10 liters of water and stirred, and then 10 g of acrylic fibers shown in Table 2 were added and stirred again. Next, 200 ppm of an anionic polyacrylamide polymer flocculant was added to the hydraulic substance while stirring at a low speed to prepare a slurry. The obtained slurry was laid on a 50-mesh wire net and was 20 cm × 25.
After being transferred to a centrifuge mold and filtered, it was pressed at a pressure of 100 kg / cm ² for 1 minute to prepare a green sheet having a thickness of about 6 mm. Next, the obtained green sheet was
% RH for 24 hours at room temperature, 6 days in 25 ° C water and 8 hours.
After curing in water at 0 ° C. for 15 hours, it was dried at 50 ° C. for 20 hours to obtain a cement board having a specific gravity of about 1.6. At this time, the moisture content of the molded article was about 6% by weight.

A test piece was cut out from the obtained cement plate,
Bending fracture was performed, and bending strength, bending strain and the number of cracks were measured. The results are shown in Table 2. Table 2 shows that the molded article of the present invention has high bending strength and bending strain and is excellent in toughness.

Examples 11 and 12 and Comparative Example 4 Using the acrylic fiber C shown in Table 1, a slurry was prepared in the same manner as in Example 1, and a slate was formed by the Hatschek method. After the obtained slate was naturally cured at room temperature for 28 days, a test piece was cut out in parallel with the molding direction, and the bending strength, bending strain and the number of cracks were measured in the same manner as in Example 1.
The results are shown in Table 2. From Table 2, it can be seen that the molded article of the present invention has large bending strength and bending strain and is excellent in toughness.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 14/00-28/36 D06M 15/00

Claims (8)

(57) [Claims] Claims: 1. A fiber-reinforced hydraulic property in which a molded article comprising an acrylic fiber and a hydraulic substance to which a surface treatment agent is adhered, at least three cracks are generated on the tensile side when subjected to bending fracture. Molding. 2. The fiber-reinforced hydraulic molded article according to claim 1, wherein the surface treating agent is a polyethylene oxide compound. 3. The fiber-reinforced hydraulic molded article according to claim 1, wherein the surface treating agent is a modified fluoro resin. 4. An acrylic fiber obtained by dry-wet spinning an acrylonitrile polymer and having a tensile strength of at least 10 g / d and an elastic modulus of at least 180.
The fiber-reinforced hydraulic molded article according to claim 1, wherein the molded article has a g / d and a knot strength of at least 1.9 g / d. 5. In producing a fiber-reinforced hydraulic molded article using a hydraulic substance and an acrylic fiber, an acrylic fiber to which a surface treatment agent for weakening the adhesive force with the hydraulic substance is attached as the acrylic fiber. A method for producing a fiber-reinforced hydraulic molded product, which is used. 6. The method according to claim 5, wherein the surface treating agent is a polyethylene oxide compound. 7. The method for producing a fiber-reinforced hydraulic molded article according to claim 5, wherein the surface treating agent is a modified fluoro resin. 8. An acrylic fiber obtained by spin-drying an acrylonitrile-based polymer, and having a tensile strength of at least 10 g / d and an elastic modulus of at least 180.
The method for producing a fiber-reinforced hydraulic molded product according to claim 5, wherein the g / d and the knot strength are at least 1.9 g / d.