JP2017222958A - Nylon fiber for reinforcing hydraulic material, method for producing nylon fiber for reinforcing hydraulic material, and hydraulic material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide low-cost nylon fiber for reinforcing a hydraulic material having high fracture energy of the hydraulic material, and a method for producing the nylon fiber for reinforcing the hydraulic material and the hydraulic material using the method therefor.SOLUTION: Provided is nylon fiber for reinforcing a hydraulic material made of short fiber. The nylon fiber is the fiber essentially consisting of nylon 66 in which a melt flow rate at 270°C is 10 to 70 g/10 min, having single fiber strength of 5.4 to 9.0 cN/dex and fracture elongation of 15 to 80%. Also provided is a method for producing the nylon fiber for reinforcing the hydraulic material where the nylon 66 in which an MFR at 270°C is 10 to 70 g/10 min is melt-spun, is subjected to wet drawing in the presence of water heated at 10 to 80°C, and is thereafter heat-set at a dry heat temperature higher than the drawing temperature. Also provided is the hydraulic material containing the nylon fiber, and containing the nylon fiber by 0.01 to 5 Vol% provided that the hydraulic material is defined as 100 Vol%.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a nylon material for reinforcing a hydraulic material, a method for producing a nylon fiber for reinforcing a hydraulic material, and a hydraulic material using the same.

  In order to reinforce the impact strength and bending strength of various hydraulic materials such as cement mortar, concrete, and cement board, short fibers obtained by cutting synthetic fibers such as nylon, polypropylene, and vinylon into a predetermined fiber length are used as reinforcing fibers. It has been. For these reinforcing fibers, fibers having high fiber strength are generally used. For this reason, polymers have been selected.

  For example, Patent Document 1 proposes to use a semi-aromatic polyamide fiber as a reinforcing fiber for cement, and Patent Document 2 proposes to use a nylon fiber as a reinforcing fiber for plastering material. Patent Document 3 proposes the use of acrylic fiber or nylon fiber as a reinforcing fiber for a mortar composition. Patent Document 4 proposes that a nylon fiber having a pulling strength, which is a stress when the fiber is broken, of 2.1 g / denier to less than 3.7 g / denier is used as a cement reinforcing fiber.

JP 09-256219 A JP 2002-274903 A JP 2001-220205 A Japanese Patent No. 4636693

  However, conventionally proposed semi-aromatic polyamide fibers and fully aromatic polyamide fibers such as aramid fibers have a problem of high production costs (for example, Patent Document 1), or hydraulic materials to which nylon fibers are added. There is a problem in the strength and fracture energy (for example, Patent Documents 2 to 4), and further improvement has been demanded.

  In order to solve the above-mentioned conventional problems, the present invention has a low manufacturing cost, and when added to various hydraulic materials, the obtained hydraulic material has a high fracture energy and the nylon fiber for reinforcing the hydraulic material, its manufacturing method and A hydraulic material using the same is provided.

  The nylon fiber for reinforcing hydraulic material of the present invention is a nylon fiber for reinforcing hydraulic material made of short fibers, and the nylon fiber has a melt flow rate (MFR) at 270 ° C. of 10 to 70 g / 10 min. Nylon fiber having 66 as a main component, single fiber strength is 5.25 to 9.0 cN / dtex, and elongation at break is 15 to 80%.

  In the method for producing a nylon fiber for reinforcing a hydraulic material according to the present invention, nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min is melt-spun and wet-stretched in the presence of water at a temperature of 10 to 80 ° C. Then, by setting heat at a dry heat temperature higher than the stretching temperature, a nylon fiber for reinforcing a hydraulic material whose main component is nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min is obtained. Features.

  The hydraulic material of the present invention is a hydraulic material containing the above-mentioned nylon fiber, and is characterized by containing 0.01 to 5% by volume of the nylon fiber when the hydraulic material is 100% by volume.

  The nylon fiber for reinforcing a hydraulic material of the present invention is a short fiber, and the nylon fiber is a nylon fiber mainly composed of nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min. Nylon fiber for reinforcing a hydraulic material having a strength of 5.25 to 9.0 cN / dtex and a breaking elongation of 15 to 80%, which is low in manufacturing cost and high in fracture energy of a hydraulic material, and the same A hydraulic material can be provided. That is, since the nylon fiber has a high affinity with the hydraulic material, the fracture energy of the hydraulic material can be increased. In addition, according to the method for manufacturing a nylon fiber for reinforcing a hydraulic material according to the present invention, the manufacturing cost is low, and the nylon for reinforcing a hydraulic material having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min as a main component is nylon 66. Fiber can be obtained.

FIG. 1 is a schematic front view showing the shape of a dumbbell and a tensile test apparatus used in one embodiment of the present invention. FIG. 2 is an explanatory view showing the breaking energy shown in one embodiment of the present invention. FIG. 3 is a graph showing the tensile stress-strain of one embodiment of the present invention. FIG. 4 is a graph showing the tensile stress-strain of another embodiment of the present invention. FIG. 5 is a graph showing the tensile stress-strain of the comparative example.

  The nylon fiber for reinforcing a hydraulic material of the present invention is a fiber mainly composed of nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min. In the following, unless otherwise indicated, nylon 66 means nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min. The fiber mainly composed of nylon 66 in the present invention means that nylon 66 occupies 50% by mass or more when the total mass of the hydraulic material reinforcing fiber is 100% by mass. Nylon 66 is mainly made of polyhexamethylene adipamide. Polyhexamethylene adipamide refers to an aliphatic polyamide composed of hexamethylenediamine and adipic acid having a melting point of 250 ° C. or higher. In the nylon fiber for reinforcing a hydraulic material of the present invention, the melting point is less than 250 ° C. Nylon 6, nylon 6I, nylon 610, nylon 6T, etc. may be copolymerized or blended as long as they are not. The nylon fiber for reinforcing a hydraulic material of the present invention contains 50 mass% or more of nylon 66 when the mass of the fiber is 100 mass%, preferably 70 mass% or more, more preferably 80 mass% or more, Particularly preferably, the thermoplastic resin constituting the hydraulic material reinforcing fiber is a fiber made of nylon 66. In the nylon fiber for reinforcing a hydraulic material of the present invention, the nylon 66 may be contained in any part of the fiber, but preferably the nylon 66 occupies at least a part of the fiber surface. If it is a single fiber, the fiber which nylon 66 occupies at least one part of the fiber surface can be manufactured by melt-spinning the raw material which has nylon 66 as a main component. A composite fiber comprising two or more types of resin components, for example, a core-sheath composite fiber having a concentric cross section, a core-sheath composite fiber having an eccentric structure, a side-by-side composite fiber, a split composite fiber, and a sea-island composite fiber In this case, the resin component including nylon 66 is preferably exposed on the fiber surface. More specifically, in the case of a core-sheath type composite fiber having a concentric circular cross section or a core-sheath type composite fiber having an eccentric structure, it is preferable to use a resin component containing nylon 66 as the sheath component. It is preferable that the resin component containing is a sea component.

  In the nylon fiber for hydraulic material reinforcement of the present invention (hereinafter, also simply referred to as nylon fiber), nylon 66 contained as the main component of the fiber has a melt flow rate at 270 ° C. of 10 to 70 g / 10 min. A preferred melt flow rate is 20 to 70 g / 10 min, a more preferred melt flow rate is 40 to 70 g / 10 min, a particularly preferred melt flow rate is 50 to 70 g / 10 min, and the most preferred melt flow rate is 55-67 g / 10 min. When the nylon 66 satisfies the above MFR, it is difficult for yarn breakage or fusion between fibers to occur in melt spinning, and high-stretching in the drawing process can be performed while suppressing the frequency of yarn breakage, In addition, the heat setting process can be performed efficiently, so it can not only be manufactured at a low manufacturing cost, but when used as a reinforcing fiber for hydraulic materials, nylon has a high affinity with hydraulic materials and a high reinforcing effect. Become fiber.

  In the present invention, the melt flow rate of nylon 66 is measured at 270 ° C. or 280 ° C. under a load of 21.2 N according to JIS K 7210. More specifically, the MFR measured by the following method is the MFR of nylon 66 in the present invention. First, a sample of nylon 66 (resin pellets or manufactured fiber) for measuring MFR is held for 5 hours in a constant temperature dryer set at 100 ° C. and sufficiently dried. Next, the temperature of the extrusion type plastometer according to JIS K 7210 is raised to a predetermined temperature, and after maintaining the predetermined temperature for 20 minutes to stabilize the temperature, 3-8 g of the dried sample is filled. Then, measurement of the melt flow rate is started 360 seconds after filling the sample. The same measurement was repeated twice, and the average value was taken as the melt flow rate of nylon 66.

  The single fiber strength of the nylon fiber is 5.25 to 9.0 cN / dtex, preferably 5.3 to 8.5 cN / dtex, more preferably 5.4 to 8.0 cN / dtex. Preferably, it is 5.4 to 7.5 cN / dtex. Further, the elongation at break is 15 to 80%, preferably 20 to 70%. If the single fiber strength and elongation at break are in the above ranges, the balance between strength and elongation is good, the affinity with hydraulic materials is high, and melt spinning, stretching, and heat setting can be performed efficiently, and the cost is low. it can. In the nylon fiber, when the single fiber strength is less than 5.25 cN / dtex or the elongation at break exceeds 80%, the strength of the fiber itself is low, so that the reinforcing effect is not given to the hydraulic material. For example, in a hydraulic material that has been cured by adding these fibers, various fracture strengths such as compressive strength, tensile strength, and bending strength have been improved compared to a hydraulic material that has been cured without the addition of various reinforcing fibers. May not be expected. When the single fiber strength of the nylon fiber exceeds 9.0 cN / dtex or the elongation at break is less than 15%, the reinforcing effect of the hydraulic material, particularly the hydraulic material containing the nylon fiber of the present invention, the fracture In addition to not expecting further improvement in energy, when manufacturing nylon fibers, it is necessary to manufacture at higher temperatures and higher draw ratios, which may increase manufacturing costs.

  Although the fineness of the nylon fiber is not particularly limited, the fineness is preferably 0.3 to 30 dtex, more preferably 0.5 to 25 dtex, and particularly preferably 0.7 to 20 dtex. The fiber length of the nylon fiber is not particularly limited, but the fiber length is preferably 1 to 50 mm, more preferably 2 to 30 mm, and particularly preferably 3 to 20 mm. If the fineness and fiber length are in the above ranges, the miscibility with the hydraulic composition is good.

  The cross-sectional shape of the nylon fiber is not particularly limited. In addition to a round cross-section, the non-circular cross-section, for example, a polygonal cross-section including a triangle and a quadrilateral, a three-leaf cross-section, and a multi-leaf including a 4-leaf cross-section. Any cross-sectional shape such as a cross-section, a Y-shape, a W-shape, or a well shape may be used. Moreover, it is good also as a solid fiber which is these cross-sectional shapes, and does not contain a hollow part, and has one or more continuous hollow parts or discontinuous hollow parts with respect to the fiber length direction in a fiber. Also good. In the nylon fiber for reinforcing a hydraulic material of the present invention, the fiber cross section is preferably a solid and round cross section. A solid and round cross-section can be manufactured at low cost. The round cross section includes various circles such as a circle, an ellipse, and an ellipse. Moreover, the cross-sectional structure of the nylon fiber for reinforcing a hydraulic material of the present invention is not particularly limited, and may be a single resin component, that is, a single fiber composed of a resin component mainly composed of nylon 66, or a plurality of For example, a core-sheath type composite fiber having a concentric cross section, a core-sheath type composite fiber having an eccentric structure, a side-by-side composite fiber, a split type composite fiber, or a sea-island type composite fiber may be used. .

  The manufacturing method of the nylon fiber for hydraulic material reinforcement of this invention is demonstrated. In the nylon fiber manufacturing method of the present invention, nylon 66 having a melt flow rate at 270 ° C. of 10 to 70 g / 10 min is melt-spun and wet-stretched in the presence of water at a temperature of 10 to 80 ° C. Heat set at a dry heat temperature higher than the temperature. First, the melt spinning process in the method for producing a nylon fiber of the present invention will be described. In the melt spinning process, nylon 66 satisfying the melt flow rate is charged into an extruder, melted at a spinning temperature of 260 to 300 ° C., extruded from a spinning nozzle, and taken up at a take-up speed of 200 to 2000 m / min. A bundle of unstretched fibers (also referred to as unstretched tows) having a fineness of 66 as a main component and a fineness of 1.5 to 100 dtex is obtained.

  The spinning temperature in the melt spinning process will be described. In the method for producing a nylon fiber for reinforcing a hydraulic material of the present invention, the spinning temperature is 260 to 300 ° C. When the spinning temperature is less than 260 ° C., when the nylon 66 is melted, its melt viscosity is high and spinnability may be extremely deteriorated, such as frequent yarn breakage. When the spinning temperature exceeds 300 ° C., the melt viscosity of the nylon 66 is too low, so that not only the unstretched fibers are fused, but the nylon 66 may start to thermally decompose during melt spinning. In the method for producing a nylon fiber of the present invention, a preferred spinning temperature is 270 ° C. to 295 ° C., and a particularly preferred spinning temperature is 270 to 290 ° C.

  The molten resin extruded from the spinning nozzle under the spinning temperature condition is taken up at a take-up speed of 200 to 2000 m / min. When the take-up speed is less than 200 m / min, not only the thickness of the nylon 66 fiber constituting the bundle of unstretched fibers is too thick, but the take-up roller is liable to be entangled during production, and the productivity may be reduced. If the take-up speed is higher than 2000 m / min, the unstretched fibers of nylon 66 are likely to be cut at the time of take-up, which may also reduce productivity. In the method for producing a nylon fiber of the present invention, the take-up speed of the undrawn fiber is preferably 300 to 1800 m / min, more preferably 350 to 1500 m / min, and particularly preferably 400 to 1200 m / min.

  Nylon 66 is melt-spun at the spinning temperature and the take-up speed to obtain an unstretched tow that is a bundle of unstretched fibers. The fineness of the nylon fiber constituting the undrawn tow, that is, the fineness of the nylon fiber before the drawing step is 1.5 to 100 dtex. If the fineness of the unstretched fiber mainly composed of nylon 66 exceeds 100 dtex, it is difficult to obtain a fiber suitable for a hydraulic material reinforcing fiber even after the stretching process. When the fineness of the unstretched fiber mainly composed of nylon 66 is less than 1.5 dtex, yarn breakage is likely to occur at the time of melt spinning, not only inferior in productivity, but also in the stretching process, the draw ratio becomes low, The resulting nylon fiber tends to have low fiber strength. In the nylon fiber production method of the present invention, the fineness of the nylon fiber after melt spinning is preferably 2 to 60 dtex, more preferably 3 to 50 dtex, and particularly preferably 3.5 to 45 dtex.

  The unstretched tow mainly composed of nylon 66 obtained by the above method is subjected to a stretching step, a heat setting step, then cut to a desired fiber length, and the hydraulic material reinforcing nylon of the present invention Fiber is obtained. In the method for producing a nylon fiber of the present invention, as a stretching step, after stretching using hot water of 10 to 80 ° C., heat setting is performed in a dry state of 100 to 200 ° C. (hereinafter also referred to as dry heat setting). First, the extending | stretching process using 10-80 degreeC warm water is demonstrated. In this stretching step, the unstretched tow mainly composed of nylon 66 is wet-stretched with warm water of 10 to 80 ° C. The reason why nylon fibers can be efficiently stretched by performing wet stretching with warm water adjusted to the above temperature range is not clear, but the secondary transition point (glass transition point) of nylon is 40 to 50 ° C. in a dry state. However, it is known that the temperature is −20 to 0 ° C. in the hygroscopic state (“Encyclopedia of Textiles”, page 793, left column, lines 2 to 14, March 25, 2002, Maruzen), It is presumed that the unstretched nylon fiber can be efficiently stretched by wet stretching in a hot water tank adjusted to this range. A preferred water temperature for the wet stretching is 15 to 70 ° C, and a particularly preferred water temperature is 20 to 70 ° C.

  In the wet stretching, the stretching ratio is preferably 2 to 6 times, more preferably 2.5 to 5.5 times, and particularly preferably 2.8 to 5.2 times. By performing wet stretching at the stretch ratio, if the temperature range of the wet stretching, unstretched nylon fiber can be sufficiently stretched, and the resulting nylon fiber is sufficient as a hydraulic material reinforcing fiber Not only does it have single fiber strength, but also the frequency of yarn breakage is suppressed in the drawing process. When the stretch ratio of the wet stretch is less than 2 times, the stretch is not sufficiently performed, so that the obtained nylon fiber has low single fiber strength, and when used as a reinforcing fiber for a hydraulic material, the cured hydraulic material There is a possibility that the strength of is not improved so much. In the wet drawing step, when the draw ratio exceeds 6 times, yarn breakage frequently occurs and the productivity may be lowered.

  Next, a dry heat setting process performed after the wet stretching process will be described. In the method for producing nylon fiber of the present invention, the dry heat setting step is performed for the purpose of promoting crystallization. By applying heat to the amorphous part of the wet-stretched nylon fiber, crystallization is further promoted, and stronger dimensional stability can be imparted. The dry heat setting step can be performed using a known dry stretching apparatus. As an example thereof, dry stretching in which the stretching process is performed in dry air with the temperature of the atmosphere adjusted to 100 to 200 ° C., or dry stretching using a metal roll whose temperature is adjusted to be 100 to 200 ° C. An example is stretching. In the method for producing a nylon fiber for reinforcing a hydraulic material according to the present invention, the heat treatment temperature when performing the dry heat setting is preferably 100 to 200 ° C, more preferably 120 ° C to 160 ° C or more, and further preferably 130 to 150 ° C. Thereby, strong heat fixation can be performed and dimensional stability can be obtained.

  In the method for producing a nylon fiber for reinforcing a hydraulic material according to the present invention, the heat setting is performed at a draw ratio such that a filament of nylon fiber (a fiber tow mainly composed of nylon 66) does not sag when it is processed. Long heat set is preferable, more preferably 0.85 to 1.5 times the draw ratio, particularly preferably 0.9 to 1.4 times the draw ratio, most preferably 0.95 to 1.2 times the draw ratio. It is preferable to perform constant length setting while satisfying the temperature range. Thereby, the nylon structure whose crystallization inside the fiber has progressed due to the wet heat drawing process can be firmly heat-fixed, and the dimensional stability and high single fiber strength can be obtained.

(Hydraulic material)
The hydraulic material of the present invention is added to the hydraulic composition so as to contain the nylon fiber for reinforcing the hydraulic material obtained by the above method in a certain ratio, and after the appropriate amount of water is added and kneaded sufficiently, it is cured. Or added to a hydraulic material slurry in which a hydraulic composition and water are already mixed, and sufficiently kneaded and then cured. The hydraulic composition contained in the hydraulic material of the present invention includes various cements, fine aggregates, and coarse aggregates, admixtures and admixtures as necessary. As the cement constituting the hydraulic composition, various cements such as ordinary Portland cement, early-strength Portland cement, super early-strength Portland cement, moderately hot Portland cement, low heat Portland cement, sulfate-resistant Portland cement can be used. it can. The fine aggregate and coarse aggregate constituting the hydraulic composition include silica sand, river sand, sea sand, beach sand, crushed stone, various slags such as blast furnace slag, ferronickel slag, copper slag, electric furnace oxidation slag, etc. From these, the particle diameter of the aggregate can be selected according to the use of the hydraulic material, and it can be used as a fine aggregate or a coarse aggregate. As the admixture contained in the hydraulic composition, fly ash, silica stone powder, silica fume, blast furnace slag fine powder, ettringite, and various known expanding materials can be used. Admixtures contained in the hydraulic composition include AE agent, AE water reducing agent, high-performance AE water reducing agent, fluidizing agent, curing accelerator, rust preventive agent, setting retarder, rapid setting agent, shrinkage reducing agent. These various admixtures can be appropriately selected and used depending on the purpose and application.

  The hydraulic material of the present invention contains 0.01 to 5 Vol% of the nylon material for reinforcing the hydraulic material. That is, in the hydraulic material, the components such as various cements, fine aggregates, coarse aggregates, water, etc., excluding the nylon material for reinforcing the hydraulic material, out of the hydraulic material, in other words, the hydraulic material. The total is 100 vol%, and the hydraulic material reinforcing nylon fiber is contained in an amount of 0.01 to 5 vol%. The hydraulic material of the present invention preferably contains 0.03 to 3 Vol%, more preferably 0.05 to 2.5 Vol% of the nylon material for reinforcing the hydraulic material. By adding the nylon fiber for reinforcing a hydraulic material of the present invention to the hydraulic material so as to have the above ratio, the fracture energy of the hydraulic material obtained by curing the hydraulic composition can be increased. When the ratio of the nylon fiber for reinforcing the hydraulic material of the present invention contained in the hydraulic material is less than 0.01 Vol%, the amount of fibers contained in the hydraulic material is small, so the fracture energy of the hydraulic material However, there is a possibility that the magnitude of the fracture energy is not much different from that of the hydraulic material not added with the hydraulic material reinforcing nylon fiber, that is, the hydraulic material reinforcing nylon fiber is not added. . If the ratio of the nylon material for reinforcing the hydraulic material of the present invention contained in the hydraulic material exceeds 5 Vol%, not only the cost increases, but also various mechanical strengths such as compressive strength and tensile strength of the hydraulic material may be lowered. .

  The hydraulic material of the present invention, that is, the hydraulic material containing the nylon fiber for reinforcing the hydraulic material of the present invention at a ratio of 0.01 to 5 Vol%, has a strain within the range of 0 to 4% in the tensile stress test. When the maximum value (A) of the tensile stress and the tensile stress value (B) when the strain is 4% are compared, B is preferably 30% or more of A, more preferably 40% or more. If it is the said range, even if distortion becomes large, the tensile stress (strength) of a hydraulic material can be maintained high.

  The fracture energy obtained from the tensile stress and displacement area of the hydraulic material is preferably 1.4 times higher than that of the hydraulic material not including the nylon fiber for reinforcing the hydraulic material of the present invention. If it is the said range, even if distortion becomes large similarly, the tensile stress (strength) of a hydraulic material can be maintained high, and it will become a hydraulic material which is hard to be destroyed.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to the following Example.

<Measurement method>
(1) Melt flow rate (MFR)
The melt flow rate of nylon 66 was measured according to JIS K 7210 at 270 ° C. and a load of 21.2 N. Specifically, a sample of nylon 66 (resin pellet or manufactured fiber) whose melt flow rate is to be measured is kept for 5 hours in a constant temperature dryer set at 100 ° C. and sufficiently dried. Next, the temperature of the extrusion type plastometer according to JIS K 7210 is raised to 270 ° C. and kept at 270 ° C. for 20 minutes to stabilize the temperature, and then 3 to 8 g of the dried sample is filled. Then, measurement of the melt flow rate is started 360 seconds after filling the sample. The same measurement was repeated twice, and the average value was taken as the melt flow rate of nylon 66 at 270 ° C.
(2) Single fiber strength and elongation at break Using a tensile tester according to JIS L 1015, the load value and elongation at the time of fiber cutting when the gripping interval of the sample was 20 mm were measured. The strength and elongation at break were taken.
(3) Tensile test of molded product of hydraulic composition Uniaxial tensile test using a dumbbell-type test body 1 having a total length of 330 mm, a grip width of 60 mm, a thickness of 30 mm, a constriction width of 30 mm, and a length of 80 mm shown in FIG. The tensile stress and strain were measured by This tensile test is based on JIS K6301. The test apparatus 10 fixes the test body 1 with the chucks 2a and 2b, and then pulls it up and down to measure the tensile stress, and measures the strain with the displacement meters 3a and 3b. In the right figure of FIG. 1, the numerical value is the dimension (unit: mm) of the dumbbell specimen.

(Examples 1-4, Comparative Examples 1-5)
Nylon 66 (Ny66) was used as a raw material polymer, melt-spun, drawn, and heat-set to obtain a fiber. The conditions and results are summarized in Table 1.

  As is clear from Tables 1 and 2, Examples 1 to 4 had high single fiber strength and good production efficiency. On the other hand, Comparative Examples 1-5 had a problem as described in the remarks column.

(Examples 5-7, Comparative Examples 6-7)
A cement mortar placing test was conducted using the fiber made of nylon 66 prepared in Example 4. Examples 5 to 7 use fibers made of nylon 66 of Example 4 (hereinafter also referred to as “nylon 66 fibers”), and Comparative Example 6 is a commercially available polypropylene (PP) reinforcing fiber (fiber length: 6 mm), Comparative Example 7 is a commercially available low-strength nylon 66 reinforced fiber (single fiber strength: 3.25 cN / dtex, elongation at break: 86%, fiber length: 12 mm. 66 fibers ") was used. Table 3 shows the materials used.

  Using materials shown in Table 3, 70 parts by mass of cement, 30 parts by mass of fly ash, 40 parts by mass of fine aggregate, 0.2 parts by mass of thickener, 0.9 parts by mass of water reducing agent, 39.1 parts by mass of water And the quantity of the reinforcing fiber shown in Table 4 was uniformly mixed to prepare a hydraulic material slurry. The fiber content (Vol%) of the reinforcing fiber shown in Table 4 is the volume ratio of the fiber to the total volume of 100% of the cement, fly ash, fine aggregate, thickener, water reducing agent and water excluding the reinforcing fiber. . In the mixing method, cement, fly ash and fine aggregate powder are first kneaded for 1 minute, then water, a water reducing agent and a thickener are added and mixed for 3 minutes, and then reinforcing fibers are added. Mixed 5 times x 2 times. The hydraulic material slurry thus obtained was placed in a mold and cured in water to produce the dumbbell shown in FIG. Using this dumbbell, a tensile test was performed to determine the initial crack strength and fracture energy. As shown in FIG. 2, the fracture energy can be expressed as stress degree × displacement = fracture energy amount. The evaluation results are summarized in Table 4.

  As apparent from Table 4, Examples 5 to 7 had high breaking energy. On the other hand, Comparative Examples 6-7 had a low breaking energy. This is presumably because the hydraulic material reinforcing fiber made of nylon 66 used in nylon examples 5 to 7 has high single fiber strength and high affinity with the hydraulic composition.

(Examples 8 to 9, Comparative Example 8)
A cement mortar placing test was conducted in the same manner as in Examples 5 and 6. Example 8 is a test in which the amount of fiber (fiber length 10 mm) made of nylon 66 used in Example 5 was shaken to 1.25 to 2.25 Vol%, and Example 9 was made from nylon 66 used in Example 5. Test in which the added amount of the resulting fiber (fiber length 20 mm) was shaken up to 1.25 to 2.25 Vol%, Comparative Example 8 was the amount of polypropylene fiber (fiber length 6 mm) used in Comparative Example 6 was 1.25 to 2 The test was shaken to 25 Vol%. The results of Example 8 are shown in FIG. 3, the results of Example 9 are shown in FIG. 4, and the results of Comparative Example 8 are shown in FIG. Further, the relationship between the maximum value (A) of the tensile stress within the range of 0 to 4% and the tensile stress value (B) when the strain is 4% is shown in Table 5 for Example 8 and Table 6 for Example 9. Comparative Example 8 is as shown in Table 7, and it can be seen that the B / A values of Examples 8 and 9 are high.

  As is apparent from FIGS. 3 to 5 and Tables 5 to 7, Examples 8 to 9 have high tensile stress at a strain of 4%, high B / A values, and high fracture energy (toughness).

  The hydraulic material reinforcing fiber mainly composed of nylon 66 of the present invention is useful as a reinforcing fiber for hydraulic materials such as cement mortar, concrete, and cement board. Further, the method for producing nylon fibers of the present invention can efficiently produce nylon 66 fibers having single fiber strength and elongation suitable for reinforcing fibers of hydraulic materials at low cost.

DESCRIPTION OF SYMBOLS 1 Test body 2a, 2b Chuck 3a, 3b Displacement meter 10 Test apparatus

Claims (9)

It is a nylon fiber for reinforcing hydraulic material consisting of short fibers,
The nylon fiber is a nylon fiber mainly composed of nylon 66 having a melt flow rate (MFR) at 270 ° C. of 10 to 70 g / 10 min.
A nylon fiber for reinforcing a hydraulic material, having a single fiber strength of 5.25 to 9.0 cN / dtex and a breaking elongation of 15 to 80%.   The nylon fiber for reinforcing a hydraulic material according to claim 1, wherein the nylon fiber has a fineness of 0.3 to 30 dtex and a fiber length of 1 to 50 mm.   The nylon fiber for reinforcing a hydraulic material according to claim 1 or 2, wherein the nylon fiber is solid and has a round cross section. A method for producing a nylon fiber for hydraulic material reinforcement,
Nylon 66 having a melt flow rate (MFR) at 270 ° C. of 10 to 70 g / 10 min is melt-spun and wet-stretched in the presence of water at a temperature of 10 to 80 ° C., and then at a dry heat temperature higher than the stretching temperature. A method for producing a nylon fiber for reinforcing a hydraulic material, characterized in that a nylon fiber mainly comprising nylon 66 having a melt flow rate (MFR) at 270 ° C. of 10 to 70 g / 10 min is obtained by heat setting.   The method for producing a nylon fiber for reinforcing a hydraulic material according to claim 4, wherein a draw ratio in the wet drawing is 2 to 6 times.   The method for producing a nylon fiber for reinforcing a hydraulic material according to claim 4 or 5, wherein the heat set is a fixed length set.   The dry heat temperature of the said heat set is 100-200 degreeC, The manufacturing method of the nylon fiber for hydraulic material reinforcement in any one of Claims 4-6. A hydraulic material comprising the nylon fiber according to any one of claims 1 to 3,
A hydraulic material characterized by containing 0.01 to 5 Vol% of the nylon fiber when the hydraulic material is 100 Vol%.   In the tensile stress test of the hydraulic material, when comparing the maximum value (A) of the tensile stress within the range of 0 to 4% and the tensile stress value (B) when the strain is 4%, B is The hydraulic material according to claim 8, which is 30% or more.

Images