JP2017119600A - Reinforcing fiber for cellulose nanofiber-carrying hydraulic molding, and hydraulic composition and hydraulic molding containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing fiber for CNF (cellulose nanofiber)-carrying hydraulic molding which can uniformly disperse CNF into a hydraulic composition; a hydraulic composition containing the reinforcing fiber; and a hydraulic molding having excellent strength formed from the hydraulic composition.SOLUTION: In a reinforcing fiber for hydraulic molding, a reinforcing fiber for hydraulic molding carrying 0.1 wt.% or more CNF with respect to the weight of the fiber on the surface of the fiber is added to a hydraulic material, the substances are mixed, and thereby the CNF is gradually separated from the surface of the reinforcing fiber and is diffused into the hydraulic material, and accordingly good dispersibility of the CNF is easily achieved. The fiber is a polyvinyl alcohol fiber.SELECTED DRAWING: None

Description

  The present invention relates to a reinforcing fiber carrying cellulose nanofiber (CNF), a hydraulic composition containing the same, and a hydraulic molded body, which are used for reinforcing hydraulic molded bodies such as cement paste, mortar, and concrete. About.

  Hydraulic inorganic substances such as cement are widely used for forming hydraulic materials such as cement paste, mortar, concrete and the like. Hydraulic molded bodies formed from these hydraulic materials are widely used as civil engineering materials and building materials. For the purpose of improving the performance such as bending strength and toughness of these molded products and suppressing cracks, it is conventionally known to add reinforcing fibers to a matrix of a hydraulic material such as concrete or cement mortar.

  In addition, in recent years, adding CNF to hydraulic molded bodies has increased strength, and in addition to improving water retention, improving heat insulation, absorbing expansion pressure when freezing moisture, and improving slump values, etc. For example, Patent Document 1 discloses a mortar or concrete composition containing CNF as nanofibers. However, when CNF is added, there is no problem in using it after being dispersed in a large amount of water as in the papermaking method. However, in the case of a method using high concentration slurry or injection molding, CNF is entangled and aggregated. As a result, the dispersibility is lowered and the strength of the molded body is reduced.

  In Patent Document 2, in order to improve the dispersibility of CNF, a study has been made to produce a CNF-containing composition by mixing a low-concentration aqueous solution of CNF with a carrier powder. After mixing, operations such as dehydration, drying, and pulverization are required, and a great deal of energy is required for production. In addition, it is difficult to make the particle size and carrying amount uniform, and there is a problem of lack of quality stability.

  Also in Patent Document 3, a cement admixture containing a CNF-containing masterbatch using a polyester-based resin has been studied in order to improve the dispersibility of CNF. In addition to the complexity of the process, such as the need to produce a master batch by refining cellulose in the resin, there was also a problem in terms of production cost.

Japanese Patent Laying-Open No. 2015-48276 JP 2013-188864 A JP2015-155357A

Accordingly, an object of the present invention is to provide a reinforcing fiber for a CNF-supported hydraulic molded body that can disperse CNF uniformly in a hydraulic composition.
Another object of the present invention is to provide a hydraulic composition comprising such reinforcing fibers.
Still another object of the present invention is to provide a hydraulic molded body formed from such a hydraulic composition and having excellent strength.

The present invention includes the following preferred embodiments.
[1] A reinforcing fiber for a hydraulic molded body in which 0.1% by weight or more of CNF is supported on the fiber surface with respect to the fiber weight.
[2] The reinforcing fiber for hydraulic molded article according to [1], wherein the reinforcing fiber for hydraulic molded article is a polyvinyl alcohol fiber.
[3] A hydraulic composition comprising the reinforcing fiber for hydraulic molded article according to any one of [1] and [2] and a hydraulic inorganic substance.
[4] The hydraulic composition according to [3], wherein the hydraulic inorganic substance is cement.
[5] A step of obtaining a hydraulic composition by kneading a mixture containing the reinforcing fiber for hydraulic molded body according to any one of [1] or [2], a hydraulic inorganic substance, and water, and a hydraulic composition The manufacturing method of the hydraulic molded object including the process of hardening after shape | molding a thing.

  The reinforcing fiber for a hydraulic molded body of the present invention is added to a hydraulic material and mixed, so that CNF is gradually detached from the surface of the reinforcing fiber and diffuses into the hydraulic material. Can be achieved.

The reinforcing fiber for a CNF-carrying hydraulic molded body of the present invention is characterized in that 0.1% by weight or more of CNF is supported on the fiber surface with respect to the fiber weight. The supported amount of CNF is preferably 0.2 to 40% by mass, more preferably 0.3 to 35% by mass, and still more preferably 0.5 to 30% by mass. When the loading amount of CNF is within the above range, it is excellent in the reinforcing effect of the hydraulic molded body, and at the same time, it is possible to suppress the decrease in fluidity of the hydraulic composition, and from the viewpoint of the productivity of the CNF-supporting reinforcing fiber. Is also advantageous.
In addition, since the hydraulic molded body to which CNF is added has excellent strength, it is possible to achieve weight reduction such as thinning of the molded body, which contributes to saving of raw materials.
In general, when reinforcing fibers are added to hydraulic materials for the purpose of improving performance such as bending strength and toughness and suppressing cracking, frictional resistance is generated between the reinforcing fibers and the matrix, and the fluidity of the matrix (slump value or flow). Value) may be lowered, causing problems in workability and the like. However, by using the CNF-supporting fiber of the present invention, an effect of suppressing a decrease in fluidity can be obtained. Although the principle of suppressing the decrease in fluidity is not clear, it is considered that the water content near the reinforcing fiber interface increases due to the water retention performance of CNF, and the effect of suppressing the frictional resistance with the matrix.

(CNF)
The CNF used in the present invention is preferably a cellulose fiber having a fiber diameter of 1 to 500 nm and an aspect ratio of 50 to 200,000. The fiber diameter is more preferably 1 to 300 nm, and further preferably 1 to 100 nm. The aspect ratio is more preferably 60 to 180,000, still more preferably 80 to 150,000, and particularly preferably 100 to 120,000. A smaller fiber diameter is preferable because the surface area per unit weight is larger, but the above range is particularly preferable in terms of water retention and adhesiveness. Moreover, although the one where an aspect ratio is larger is preferable at the surface of the strength improvement in a hydraulic molded object, if it is the said range, it is preferable at the point which can make intensity | strength improvement and workability compatible. If the aspect ratio is too large, CNF may be entangled in the hydraulic composition.

Examples of cellulose used as a raw material for CNF include regenerated cellulose fibers such as pulp, cotton, paper, rayon / cupra / polynosic rayon, and cellulose derived from animals such as bacteria-produced cellulose and sea squirt. These celluloses may be obtained by chemically modifying the surface as necessary.
Moreover, you may use the cellulose powder which crushed the cellulose. Examples of the cellulose powder include commercially available products such as “KC Flock” manufactured by Nippon Paper Industries Co., Ltd., “Theolas” manufactured by Asahi Kasei Chemicals Corporation, and “Avicel” manufactured by FMC Biopolymer.

(Reinforcing fiber for hydraulic molded body)
In the present invention, the reinforcing fiber for a hydraulic molded body that supports CNF can be used without limitation both organic fibers and inorganic fibers, but is preferably alkali-resistant since cement and the like are alkaline. Examples of inorganic fibers include alkali-resistant glass fibers, steel fibers (steel fibers), stainless fibers, and carbon fibers. Examples of organic fibers include polyvinyl alcohol fibers (hereinafter sometimes referred to as PVA fibers), polyolefins. Fiber (polyethylene fiber, polypropylene fiber, etc.), ultra high molecular weight polyethylene fiber, polyamide fiber (polyamide 6, polyamide 6,6, polyamide 6,10 etc.), aramid fiber (especially para-aramid fiber), polyparaphenylenebenzobisoxazole Fiber (PBO fiber), Krill fibers, rayon fibers (polynosic fibers, solvent-spun cellulose fibers, etc.), polyphenylene sulfide fibers (PPS fibers), polyetheretherketone fibers (PEEK fibers) and the like.

  Among these, alkali resistant glass fiber, carbon fiber, PVA fiber, polyolefin fiber (polyethylene fiber, polypropylene fiber, etc.), acrylic fiber, aramid fiber, etc. can be manufactured at low cost while having concrete reinforcement. Can be advantageously used.

  In addition, PVA fibers are particularly preferable from the viewpoint of better adhesion to the cement after curing and further improving the reinforcement in the hydraulic molded body. When a PVA fiber is used, a hydrogen bond is generated between the hydroxyl group of CNF and the hydroxyl group of PVA, so that CNF is easily supported on the fiber surface.

  The degree of polymerization of the PVA polymer constituting the PVA fiber used in the present invention can be appropriately selected according to the purpose and is not particularly limited. However, considering the mechanical properties of the resulting fiber and the like, The average degree of polymerization determined from the viscosity is preferably 500 to 20000, more preferably 800 to 15000, and still more preferably 1000 to 10,000. Particularly, from the viewpoint of strength, it is preferably 1000 or more, more preferably 1200 or more, further preferably 1500 or more, and particularly preferably 1750 or more.

  The saponification degree of the PVA-based polymer constituting the PVA-based fiber used in the present invention can be appropriately selected according to the purpose and is not particularly limited, but is preferably 95 mol% from the viewpoint of the mechanical properties of the resulting fiber. It is above, More preferably, it is 98 mol% or more, More preferably, it is 99 mol% or more, Most preferably, it is 99.8 mol% or more. If the saponification degree of the PVA polymer is too low, it is often not preferable in terms of mechanical properties, process passability, production cost, and the like of the obtained fiber. Moreover, the upper limit of the saponification degree of the PVA-type polymer which comprises the PVA-type fiber used for this invention is 100 mol% normally.

  The fiber diameter of the reinforcing fiber can be appropriately selected depending on the size of the aggregate such as sand or gravel used as the hydraulic material, and is not particularly limited. When using a PVA-type fiber, a thing of 100-700 micrometers can be used from points, such as intensity | strength and productivity.

  The aspect ratio of the reinforcing fiber is preferably 30 to 500, more preferably 35 to 470, and still more preferably 40 from the viewpoint of achieving both the dispersibility of the fiber in the hydraulic composition and the reinforcing property after curing. ~ 450. When the aspect ratio is larger than 500, the dispersibility of the fibers may be remarkably deteriorated due to entanglement of the fibers. When the aspect ratio is smaller than 30, the fibers are easily removed and there is a possibility that sufficient reinforcement cannot be exhibited. The aspect ratio means the ratio (L / D) between the fiber length (L) and the fiber diameter (D).

  The fiber strength of the reinforcing fiber is preferably 6 cN / dtex or more, more preferably 7 cN / dtex or more, and further preferably 8 cN / dtex or more. The upper limit of the fiber strength can be appropriately set according to the fiber and is not particularly limited, but may be about 30 cN / dtex. The fiber strength can be measured by the tensile strength at break according to JIS L1015 “Testing method for chemical fiber staples (8.5.1)”.

(Production method)
The reinforcing fiber for CNF-supported hydraulic molded body of the present invention is obtained by a method including, for example, a step of adjusting a CNF dispersion and a step of supporting CNF on the reinforcing fiber for a hydraulic molded body using the CNF dispersion. be able to.

[(1) Preparation of CNF dispersion]
The cellulose fibers can be made into nanofibers by mechanically applying shearing force to the cellulose fibers obtained from the cellulose. Examples of the method for imparting the shearing force include a method using an extruder such as a bead mill, an ultrasonic homogenizer, a single screw extruder, a twin screw extruder, a Banbury mixer, a grinder, a pressure kneader, a two-roll kneader, or the like. Can be mentioned.
The CNF dispersion is obtained by dispersing CNF in a dispersion medium. As the dispersion medium, any solvent that can disperse CNF can be used without any particular limitation. For example, organic solvents such as water, alcohols such as methanol and ethanol, etc. A solvent or a mixture thereof can be used.

The CNF concentration in the CNF dispersion is not particularly limited, but is preferably 0.5% to 40% by weight, more preferably 1% to 35% by weight, and further preferably 2% to 30% by weight. It is. If the concentration is too high, the viscosity of the dispersion becomes high, and it may be difficult to uniformly support the reinforcing fiber. In addition, if the concentration is too low, the energy and time required for drying the dispersion medium after being supported on the reinforcing fiber is increased, and the amount of CNF supported on the reinforcing fiber is likely to be relatively reduced, resulting in a hydraulic property that is finally obtained. In some cases, it is difficult to obtain an effect such as strength improvement in the molded body.
CNF can also be obtained as a liquid material dispersed in water or the like, and for example, commercially available products such as “Cerish” manufactured by Daicel Chemical Industries, Ltd. can be used.

  In the production process of the reinforcing fiber for a CNF-supported hydraulic molded body of the present invention, a binder resin can be added to the CNF dispersion for the purpose of adjusting the amount of CNF supported and the detachability. As the binder resin, water-soluble resins such as polyvinyl alcohol, acrylic, and polyethylene glycol can be used. By adjusting the loading amount and detachability of CNF, not only can the strength of the hydraulic molded body be further improved, but also by adjusting the state of the interface between the reinforcing fibers and the matrix in the hydraulic composition Moreover, it becomes possible to suppress the fall of the fluidity | liquidity of a hydraulic composition.

  Moreover, as long as the effects of the present invention are not impaired, surfactants, antioxidants, decomposition inhibitors, antifreeze agents, and the like, depending on the purpose, such as enhancing dispersion stability and viscosity stability in CNF dispersions. Further, additives such as a pH adjuster, a masking agent, a coloring agent, and an oil agent may be used.

[(2) CNF loading on reinforcing fibers for hydraulic molded body]
After spinning or spinning-drying the reinforcing fiber for hydraulic molded body, for example, CNF is supported on the surface of the reinforcing fiber for hydraulic molded body by using the CNF dispersion obtained by the above-described method. As a method for supporting CNF, for example, a method in which fibers are immersed in a CNF dispersion and the CNF dispersion is adhered to the fiber surface, a method in which the CNF dispersion is applied to the fiber surface using a roller, or the like is used. And spraying the fiber surface. Such treatment may be performed on a fiber tow composed of a plurality of fibers. The reinforcing fiber for hydraulic molded body may be stretched and / or cut as necessary after spinning and before applying the CNF dispersion. In the case of carbon fiber, the CNF dispersion may be applied to the fiber tow that has undergone the firing process after spinning and drying.
If necessary, the reinforcing fiber for hydraulic molded body may be cut after applying the CNF dispersion and before the drying step.

Subsequently, the dispersion medium is dried and removed from the surface of the reinforcing fiber for hydraulic molded body.
The drying temperature is not particularly limited as long as the temperature is lower than the softening point of the polymer constituting the reinforcing fiber for hydraulic molded body when the reinforcing fiber for hydraulic molded body is organic fiber, and the dispersion medium can evaporate. .

  CNF only needs to be supported on at least a part of the surface of the reinforcing fiber for hydraulic molded body, and in particular, it may be supported on a part of the side surface with respect to the length direction of the fiber, but is supported on the entire side surface. It is preferable. The fiber end face does not necessarily have to be supported.

The thus obtained reinforcing fiber for CNF-carrying hydraulic shaped body is characterized in that 0.1% by weight or more of CNF is supported on the fiber surface with respect to the fiber weight.
In addition, the CNF-supported hydraulic molded body reinforcing fiber according to the present invention is added to and mixed with the hydraulic material, so that part of the CNF is detached from the reinforcing fiber and gradually dispersed in the matrix. Since the reinforcing effect of the rigid molded body can be obtained, the weight of the molded body can be reduced and the material can be saved.
In general, when reinforcing fibers are added to a hydraulic material for the purpose of improving performance such as bending strength and toughness and suppressing cracking, friction resistance occurs between the reinforcing fibers and the matrix, and the fluidity (slump value) of the hydraulic composition However, the CNF-supporting hydraulic molded body reinforcing fiber of the present invention has a flow of hydraulic composition by supporting CNF on the surface. The effect which suppresses a fall of property is also acquired. Although the principle of suppressing the decrease in fluidity is not clear, it is considered that the water content near the reinforcing fiber interface increases due to the water retention performance of CNF, and the effect of suppressing the frictional resistance with the matrix.

  The force that the reinforcing fiber for hydraulic compact supports CNF is a mechanical interaction such as hydrogen bond or ionic bond, physical interaction such as van der Waals force, or anchor effect on the unevenness of the reinforcing fiber surface. However, when added to a hydraulic matrix, those having a lower supporting force due to moisture in the matrix are preferable, and more specifically, hydrogen bonds are more preferable.

  Further, as described above, a binder resin may be added to the CNF dispersion for the purpose of adjusting the amount of CNF supported and the detachability in the production process of the CNF-supported hydraulic molded body reinforcing fiber of the present invention. However, not only can the strength of the hydraulic molded body be further improved by adjusting the amount of CNF supported and the detachability by using a binder resin or devising the surface state of the fiber, It is also possible to adjust the state of the interface between the reinforcing fiber and the matrix in the hydraulic composition, and it is possible to suppress a decrease in fluidity of the hydraulic composition.

  In order to achieve both the reinforcement of the hydraulic molded body by CNF and the effect of suppressing the decrease in fluidity of the hydraulic composition, on the surface of the reinforcing fiber after stirring the reinforcing fiber for CNF-supported hydraulic molded body in water The residual CNF ratio is preferably 0.1 to 50% by weight, more preferably 0.5 to 40% by weight. When the CNF residual ratio exceeds 50% by weight, the supported CNF is difficult to diffuse into the hydraulic composition, and the reinforcing effect by CNF may be difficult to obtain. In addition, when the residual ratio of CNF is less than 0.1% by weight, CNF may be peeled off in a lump at the beginning of stirring after being added to the hydraulic material, and good dispersion of CNF may not be obtained. The effect may be difficult to obtain.

[Hydraulic composition]
The hydraulic composition of the present invention includes at least a hydraulic inorganic substance and the reinforcing fiber for a CNF-supported hydraulic molded body. By hardening the hydraulic composition of the present invention, a hydraulic molded body reinforced with fibers can be obtained.

  Examples of the hydraulic material used in the hydraulic composition of the present invention include those containing cement and those containing gypsum. Examples of the hydraulic material containing cement include cement paste, mortar, and concrete. The cement paste contains cement and water, the mortar contains cement, water and fine aggregate, and the concrete (fresh concrete) usually contains cement, water, fine aggregate and coarse aggregate. These materials may contain various admixtures (admixtures / admixtures) as necessary. In the present invention, CNF-supported hydraulic molded body reinforcing fibers are included, and this is the present invention. It is a hydraulic composition. Further, a cement composition, a mortar composition, and a concrete composition composed of a mixture of solids before the addition of water can also be cited as the hydraulic material according to the present invention. By adding water to these compositions and kneading, a hydraulic material containing water such as cement paste, mortar, concrete, or the like can be formed.

  Examples of the hydraulic inorganic substance contained in the hydraulic material include cement and gypsum. Examples of the cement (hydraulic cement) include ordinary Portland cement, early-strength Portland cement, low heat cement, medium temperature heat Portland cement and other Portland cement, alumina cement, blast furnace cement, silica cement, fly ash cement, eco cement, and the like. It is done. Examples of gypsum include dihydrate gypsum, α-type or β-type hemihydrate gypsum, and anhydrous gypsum. These hydraulic inorganic substances may be used alone or in combination of two or more. These hydraulic inorganic substances are usually used in a powder (fine particle) state, and react with the added water to condense and harden the hydraulic material.

  As described above, various kinds of admixtures may be mixed in the hydraulic material as necessary. Here, the admixture is a substance mixed in the hydraulic material in addition to the hydraulic inorganic substance, water, and aggregate. Examples of the admixture include admixtures such as silica fume, fly ash, blast furnace slag fine powder, limestone powder, quartz powder, AE agent, fluidizing agent, water reducing agent, high performance water reducing agent, AE water reducing agent, high performance AE. Examples thereof include a water reducing agent, a thickening agent, a water retention agent, a water repellent, a swelling agent, a curing accelerator and a setting retarder. These admixtures may be used alone or in combination of two or more.

  The amount of the reinforcing fiber, the hydraulic inorganic substance, the aggregate, the admixture, and the like, and the amount of water added can be appropriately adjusted according to the desired molded article, and a known amount may be used as appropriate. The CNF-supported hydraulic molded body reinforcing fiber of the present invention can impart high fluidity to the hydraulic material by the action of CNF, so the amount of water reducing agent, fluidizing agent, etc. used can be reduced. The strength of the molded body can be improved.

  As described above, the preferred embodiments of the present invention have been described, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention, and such modifications are also included in the scope of the present invention. It is.

[CNF loading]
The value obtained by subtracting the weight of the fiber sample per 15 m before carrying CNF from the weight of the fiber sample per 15 m after carrying CNF was taken as the CNF carrying amount.

[CNF remaining rate after stirring in water]
The residual CNF rate after stirring in water was determined by the following method. The CNF-supporting reinforcing fiber cut to 15 mm was stirred at 1000 counts with a TAPPI disintegrator at a CNF-supporting reinforcing fiber / water ratio of 10 g / 1 liter. The amount of CNF supported after stirring in water (A) is measured from the weight of the CNF-supported reinforcing fiber taken out from the disaggregator and dried, and from the amount of CNF supported (B) determined in (A) and the previous item, the following formula is used. The survival rate was determined.

[Flowability of hydraulic composition]
The flow value was evaluated as an index representing the fluidity of the hydraulic composition. The measurement was performed according to the method described in the physical test method of JISR 5201 cement. The hydraulic composition was filled into a flow cone. Next, at the time point 120 seconds after removing the flow cone, measurement was performed in the direction (horizontal) in which the diameter of the expanded hydraulic composition was recognized as the maximum, and the direction perpendicular to this (vertical), and the average value was mm. It is shown as an integer with the unit.

[Dispersibility of CNF]
When measuring the fluidity, the surface of the spread hydraulic composition was observed, and the dispersibility of CNF was visually determined.
<Criteria>
◯: Bulk CNF having a maximum diameter of 10 mm or more is not recognized and uniformly dispersed Δ: 5 or less of the CNF is recognized ×: 6 or more of the CNF is recognized CNF Agglomerates formed by agglomeration and agglomerates formed by agglomeration of reinforcing fibers for CNF-carrying hydraulic shaped bodies can be discriminated visually by the difference in fiber diameter.

[Strength of hydraulic compact]
It was carried out according to the compressive strength test method of JIS A 1108 concrete. The mortar kneaded with a mixer is poured into a mold with a diameter of 50 mm and a height of 100 mm, sealed and cured in a room at 20 ° C. for 48 hours, wrapped in a compress, and kept at a constant temperature and humidity of 90 ° C. and 98% humidity. It was subjected to wet heat curing in a tank for 48 hours and subjected to a strength test. The compressive strength test was conducted with a universal testing machine having a maximum capacity of 2000 kN.

[Example 1]
[Manufacture of CNF-supporting fibers]
As reinforcing fibers for hydraulic molded bodies, polyvinyl alcohol fibers (PVA fibers) “RF1000” (manufactured by Kuraray Co., Ltd./fiber diameter: about 310 μm) were used. Moreover, “Cerish KY100S” (manufactured by Daicel Chemical Industries, Ltd./CNF concentration 25% by weight, dispersion medium: water) was used as the CNF dispersion. After immersing “RF1000” before cutting in a treatment tank containing “Serish KY100S” for 10 seconds, drying is performed under hot air at 120 ° C. to evaporate the dispersion medium (water), thereby CNF on the surface of the PVA fiber. Was supported. The amount of CNF supported was 25.5% by weight. Thereafter, the CNF-supporting PVA fiber was cut into a fiber length of 15 mm to obtain a CNF-supporting PVA short fiber having an aspect ratio of 50. The residual CNF rate after stirring in water was 3.2%.

  In Hobart mixer, 600 parts by weight of ordinary cement (manufactured by Taiheiyo Cement Co., Ltd.), 400 parts by weight of silica fume (manufactured by EFACO), 900 parts by weight of fine aggregate (No. 6.5 cinnabar: maximum diameter of about 1 mm), 150 weights of water 25 parts by weight of a polycarboxylic acid-based high-performance AE water reducing agent (“SSP-104” manufactured by Takemoto Yushi Co., Ltd.) in a volume of about 2 L for 12 minutes, and the resulting plain mortar is mixed with the CNF-supported PVA 25 parts by weight of the fiber was added and additional kneading was performed for 2 minutes to prepare a fiber reinforced mortar as a hydraulic composition.

  Next, after measuring the flow value, the fiber reinforced mortar was poured into a mold having a diameter of 50 mm and a height of 100 mm, and then sealed and cured in a room at 20 ° C. for 48 hours. Wet and heat curing was performed for 48 hours in a constant temperature and humidity chamber with a humidity of 98% to prepare a hydraulic molded body.

[Example 2]
80 parts by weight of water as a dispersion medium was added to 20 parts by weight of “Serisch KY100S”, and the mixture was stirred and mixed at room temperature for about 10 minutes to prepare a CNF aqueous dispersion having a CNF concentration of 5% by weight. A CNF-supporting PVA fiber was obtained in the same manner as in Example 1 except that this CNF dispersion was used. The amount of CNF supported was 4.5% by weight. The residual CNF rate after stirring in water was 8.3%. Using the CNF-supported PVA fiber, a hydraulic composition and a hydraulic molded body were produced by the same procedure as in Example 1.

[Example 3]
As a water-soluble binder resin, 85 parts by weight of a PVA aqueous solution in which 5 parts by weight of “PVA205” (manufactured by Kuraray Co., Ltd./polyvinyl alcohol resin) was previously dissolved in 80 parts by weight of water was added to 20 parts by weight of “Serisch KY100S”. CNF aqueous dispersion was prepared by stirring and mixing at room temperature for about 10 minutes.
The CNF dispersion was applied to steel fiber “CW2215” (manufactured by Tokyo Steel Corporation / diameter 220 μm, fiber length 15 mm) and dried to prepare CNF-supporting steel fibers. The amount of CNF supported was 4.5% by weight. The residual CNF rate after stirring in water was 5.3%. A hydraulic composition and a hydraulic compact were produced in the same procedure as in Example 1 except that 120 parts by weight of CNF-carrying steel fiber was added.

[Comparative Example 1]
A PVA fiber, a hydraulic composition, and a hydraulic molded body were produced in the same manner as in Example 1 except that the PVA fiber was obtained without supporting the CNF dispersion.

[Comparative Example 2]
Example 1 except that 40 parts by weight of CNF dispersion (CNF concentration 12.5% by weight / dispersion medium: water) was added to plain mortar (5 parts by weight of CNF dry weight) and then PVA fiber was added. The hydraulic composition was prepared. Even when the additional kneading was performed for 2 minutes, the bulk CNF was not released, and further, the kneading was performed for an additional 5 minutes. However, the bulk CNF was not eliminated and the CNF was separated.

  CNF is said to contribute to the improvement of the compression strength of the molded body by being uniformly dispersed in the hydraulic composition. However, by using the reinforcing fiber for CNF-supported hydraulic molded body of the present invention, CNF is a hydraulic composition. Since it was uniformly dispersed in the product, Examples 1 to 3 all showed higher compressive strength than Comparative Examples 1 and 2, and the effect was obtained when the same type of fibers were used (Example 1 and Example 2). There was a tendency to depend on the amount of CNF supported.

  The use of hydraulic materials such as cement paste, mortar, concrete, etc., in which the reinforcing fibers for hydraulic molded bodies of the present invention are blended is not particularly limited, and can be used as various construction materials and civil engineering materials.

Claims (5)

A reinforcing fiber for a hydraulic molded body in which 0.1% by weight or more of CNF is supported on the surface of the fiber. The reinforcing fiber for hydraulic molded bodies according to claim 1, wherein the reinforcing fibers for hydraulic molded bodies are polyvinyl alcohol fibers. A hydraulic composition comprising the reinforcing fiber for hydraulic molded body according to claim 1 and a hydraulic inorganic substance. The hydraulic composition according to claim 3, wherein the hydraulic inorganic substance is cement. A step of kneading a mixture containing the reinforcing fiber for hydraulic molded body according to claim 1 or 2, a hydraulic inorganic substance, and water to form a hydraulic composition, and molding the hydraulic composition The manufacturing method of the hydraulic molded object including the process hardened | cured after carrying out.