Convergence yarn, method for producing convergence yarn, aqueous sizing composition, hydraulic composition, and molded body

Abstract

The present invention addresses the problem of providing convergence yarn and a hydraulic composition that are used to obtain a molded body having high toughness and small variations in toughness.　The present invention relates to a convergence yarn containing multiple fibers integrated by a convergence agent. The convergence agent is a water-soluble resin. The convergence yarn further contains an oil. The oil content is at least 5 mg / m2 per unit surface area of the fibers.

Description

Bundling yarn, method for producing the same, aqueous sizing composition, hydraulic composition, and molded body

[0001] The present invention relates to a bundle yarn, a method for producing the bundle yarn, an aqueous sizing composition, a hydraulic composition, and a molded article.

[0002] It has been known to incorporate reinforcing fibers into a matrix containing a hydraulic material for the purpose of improving mechanical strength such as bending strength and toughness of molded articles, which are hardened products of hydraulic materials such as concrete and cement mortar, and suppressing cracking, etc. However, it is extremely difficult to uniformly disperse the fibers in the matrix, and the fibers may become entangled during mixing with the hydraulic material, forming clumps (fiber balls), and the formation of clumps makes it difficult for the fibers to exert their reinforcing effect.

[0003] As a means for solving the above problems, for example, Patent Document 1 describes a sizing thread that is solidified with a water-soluble sizing agent and has a defibration rate of 20% or more in a concrete molded product. Also, Patent Document 2 discloses a sizing thread that is sizing-up with a water-soluble polymer resin and has a defibration rate of 50% or more at pH 12.

[0004] Japanese Patent Publication No. 64-1424 Japanese Patent Publication No. 10-183473

[0005] In Patent Document 1, a water-soluble polymer that is water-soluble and has film-forming ability is used as the water-soluble sizing agent. However, when fibers are sizing using a water-soluble polymer with high film-forming ability, it is difficult to increase the degree of defibration, and the strength of the molded body cannot be sufficiently increased. In Patent Document 2, since the fibers are sizing using only a water-soluble resin, a long kneading time is required, which causes buckling of the fibers. As a result, the defibrated fibers are likely to form fiber balls, and the strength of the molded body cannot be sufficiently increased. In particular, conventional bundling yarns are not able to sufficiently increase the toughness of the molded body, and there is variation in performance, leaving room for improvement.

[0006] Therefore, an object of the present invention is to provide a binder yarn and a hydraulic composition that give a molded article having high toughness and small variation in toughness.

[0007] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention includes the following preferred embodiments: [1] A sizing yarn including a plurality of fibers integrated together by a sizing agent, the sizing agent being a water-soluble resin, and the sizing yarn further contains 5 mg / m2 of sizing agent per unit surface area of ​​the fibers. ２ [2] A bundle yarn containing an oil agent in a content of 30 mg / m per unit surface area of ​​the fiber. ２ [3] The bundle yarn according to [1], containing an oil agent in a content of 500 mg / m or more per unit surface area of ​​the fiber. ２ The convergence yarn according to [1] or [2], which contains an oil agent in the following content: [4] The convergence yarn according to any one of [1] to [3], in which the sizing agent and the oil agent are in a mixed state. [5] The convergence yarn according to any one of [1] to [4], in which the average fiber diameter of the fibers is 3 to 900 μm. [6] The convergence yarn according to any one of [1] to [5], in which the oil agent contains oil and / or a surfactant. [7] The convergence yarn according to any one of [1] to [6], in which 60% by mass or more of the water-soluble resin dissolves when 2 parts by mass of the water-soluble resin is added to 100 parts by mass of alkaline water of pH 12 and stirred at 20°C for 5 minutes. [8] The convergence yarn according to any one of [1] to [7], in which the water-soluble resin contains a constituent unit derived from vinyl alcohol. [9] The water-soluble resin has a content of 4 mg / m per unit surface area of ​​the fiber. ２

[10] The water-soluble resin is contained in the bundle yarn at a content of 200 mg / m per unit surface area of ​​the fiber. ２The convergent yarn according to any one of [1] to [9], wherein the convergent yarn is contained in the following content:

[11] The convergent yarn according to any one of [1] to

[10] , wherein the ratio (Y / X) of the oil content (Y mass%) based on the total amount of the convergent yarn to the water-soluble resin content (X mass%) based on the total amount of the convergent yarn is 1 to 15.

[12] The convergent yarn according to any one of [1] to

[11] , wherein the aspect ratio of the fibers is 30 to 2,500.

[13] A method for producing a convergent yarn comprising a plurality of fibers, comprising the following step 1: (Step 1) a step of adhering an oil-in-water dispersion containing a sizing agent that is a water-soluble resin, an oil, and water to the surface of the fibers;

[14] The production method according to

[13] , wherein the average particle diameter of dispersed particles contained in the oil-in-water dispersion is 1 to 500 nm;

[15] A convergent yarn produced by the production method according to

[13] or

[14] .

[16] An aqueous sizing composition comprising a sizing agent which is a water-soluble resin, an oil agent, and water, wherein the water content is 80 mass% or more based on the total amount of the aqueous sizing composition, and the aqueous sizing composition is an oil-in-water dispersion, and the average particle size of the dispersed particles is 1 to 500 nm.

[17] A hydraulic composition comprising at least the sizing thread according to any one of [1] to

[12] , a cement component, an aggregate, and water.

[18] The hydraulic composition according to

[17] , wherein the aggregate does not contain coarse aggregate.

[19] The hydraulic composition according to

[17] or

[18] , wherein the ratio of the mass of water to the mass of cement component (water / cement component) is 20 to 75 mass%.

[20] A molded product obtained by curing the hydraulic composition according to any one of

[17] to

[19] .

[21] The converging yarn according to any one of [1] to

[12] , which is produced using an oil in an oil-in-water dispersion having a solids concentration of 25 mg / L and an average particle size of 0.1 to 800 nm.

[0008] According to the present invention, it is possible to provide a binder yarn and a hydraulic composition that give a molded article having high toughness and small variation in toughness.

[0009] Hereinafter, embodiments of the present invention will be described in detail, but it is not intended that the present invention be limited to the following embodiments.

[0010] The bundle yarn of the present invention is a bundle yarn containing a plurality of fibers integrated by a sizing agent, the sizing agent being a water-soluble resin, and the bundle yarn further has a sizing of 5 mg / m per unit surface area of ​​the fibers. ２ The oil agent is contained in an amount of 1000 or more. The convergence yarn is usually dispersed in a hydraulic composition containing at least a hydraulic material and water, and the hydraulic composition is cured to obtain a molded body. The hydraulic composition is produced, for example, by mixing the convergence yarn and the hydraulic material in a dry state and gradually adding water while stirring the mixture. The addition of water dissolves the sizing agent, and the shear force caused by stirring loosens and defibrates the bundled fibers. It is believed that the reinforcing effect of the fibers on the hydraulic material can be enhanced by dispersing the fibers contained in the convergence yarn as single fibers as uniformly as possible in the hydraulic composition matrix without damaging the fibers. It is believed that the inclusion of an appropriate amount of oil agent in the convergence yarn allows the water-soluble resin to be dispersed more uniformly on the fiber surface as small domains, resulting in more rapid and uniform defibration of the convergence yarn by adding water. Furthermore, in a molded body obtained by hardening the hydraulic composition, the presence of an oil agent on the surface of the defibrated fibers adjusts the adhesion between the fibers and the cement matrix within an appropriate range, and when cracks or the like occur in the molded body, the fibers slide while maintaining a certain degree of adhesion, which is thought to improve the toughness of the molded body. In particular, since the converging yarn of the present invention contains a specific amount or more of an oil agent, it is thought that the particles formed by the oil agent can disperse the water-soluble resin more uniformly as small domains on the fiber surface.

[0011] (Oil agent) The converging yarn of the present invention has an oil content of 5 mg / m per unit surface area of ​​the fiber. ２ The composition contains at least one oil agent at a content of 100 or more. The oil agent is an organic component containing at least an oil and / or a surfactant, and may contain one type of oil and / or surfactant, or may be a mixture containing two or more types of oil and / or surfactant. Examples of the oil agent include oils such as low-polarity oils and high-polarity oils, surfactants, etc. The oil agent may contain at least one surfactant.

[0012] The oil used in the present invention preferably contains a surfactant, and more preferably contains a surfactant and a low-polarity oil.

[0013] The oil agent used in the present invention is an organic component containing at least an oil and / or a surfactant, and the oil is a component classified as a low-polarity oil or a high-polarity oil. The oil agent may also contain a surfactant. The total amount of oil and / or surfactant in the oil agent is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more, based on the total amount of the oil agent. The oil agent used in the present invention preferably contains an oil or a surfactant, more preferably contains a surfactant, even more preferably contains an oil and a surfactant, and even more preferably contains a low-polarity oil and a surfactant. The amount of oil contained in the oil agent is not particularly limited, but from the viewpoints of stability in the oil agent production process, the desired fiber bundle state, and the adhesive state in the composite, it is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, even more preferably 70 to 98% by mass, even more preferably 75 to 95% by mass, and especially preferably 80 to 95% by mass, based on the total amount of the oil agent.

[0014] Low-polarity oils are oils that do not contain any of anionic groups, cationic groups, polyoxyalkylene groups, or fatty acid ester groups. Examples of low-polarity oils include hydrocarbon oils such as paraffinic oils, naphthenic oils, and polybutenes, as well as oxidized polyolefins. Low-polarity oils do not function as surfactants. The amount of low-polarity oil in the oil agent is preferably 60 to 98% by mass, more preferably 70 to 97% by mass, and even more preferably 80 to 95% by mass, based on the total amount of the oil agent, from the viewpoints of stability in the oil agent manufacturing process, the desired fiber bundle state, and the adhesive state in the composite material. In a preferred embodiment, the oil agent contains at least one type of low-polarity oil. In this embodiment, the oil agent may contain one type of low-polarity oil, or two or more types of low-polarity oils.

[0015] The highly polar oil is an oil that has a polar group but is not a surfactant. For example, it is an oil that has at least one polar group selected from the group consisting of an anionic group, a cationic group, a polyoxyalkylene group, and a fatty acid ester group, but does not exhibit surfactant properties. The amount of highly polar oil in the oil agent is preferably 0 to 60% by mass, more preferably 0 to 50% by mass, and even more preferably 0 to 40% by mass, based on the total amount of the oil agent, from the viewpoint of improving the toughness of the molded article obtained using the bundle yarn and suppressing variation.

[0016] (Surfactant) The surfactant has surface activity and may be an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant. In a preferred embodiment, the oil contains at least one surfactant. In this embodiment, the oil may contain one or more surfactants. For example, in addition to at least one oil, the oil may further contain one or more surfactants. The surfactant is preferably at least one selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and / or nonionic surfactants, and more preferably a nonionic surfactant. From the viewpoint of the stability of the oil, the amount of surfactant in the oil is preferably 2 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 5 to 20% by mass, based on the total amount of the oil.

[0017] In one embodiment of the present invention, the oil preferably contains one or more surfactants. In addition to at least one surfactant, the oil may further contain one or more oils. The amount of surfactant in the oil may be 2 to 50 mass%, 2 to 70 mass%, or 2 to 80 mass%, but from the viewpoint of oil stability, it is preferably 2 to 100 mass%, more preferably 3 to 95 mass%, and even more preferably 5 to 90 mass% based on the total amount of the oil. In an embodiment in which the oil contains a surfactant and an oil (preferably a low-polarity oil), the total amount of surfactant and oil in the oil is preferably 60 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, even more preferably 95 mass% or more, and particularly preferably 98 mass% or more based on the total amount of the oil. The upper limit of the total amount of surfactant and oil may be 100 mass% or less.

[0018] The amount of oil in the oil agent is not particularly limited, but in one embodiment of the present invention, from the viewpoints of the stability of the oil agent in the manufacturing process, the desired state of fiber convergence, and the desired state of adhesion in the composite material, the amount of oil may be preferably 10 to 98 mass%, more preferably 5 to 97 mass%, and even more preferably 0 to 95 mass%, based on the total amount of the oil agent.

[0019] Anionic surfactants are surfactants having at least one anionic group, such as a carboxylic acid group, a sulfonic acid group, a sulfate ester group, or a salt thereof.

[0020] Examples of anionic surfactants include fatty acids (salts) such as oleic acid, palmitic acid, sodium oleate, potassium palmitate, and triethanolamine oleate; hydroxyl group-containing carboxylic acids (salts) such as hydroxyacetic acid, potassium hydroxyacetate, lactic acid, and potassium lactate; polyoxyalkylene alkyl ether acetic acids (salts) such as polyoxyethylene tridecyl ether acetic acid (sodium salt); salts of carboxyl group-polysubstituted aromatic compounds such as potassium trimellitate and potassium pyromellitate; alkylbenzene sulfonic acids (salts) such as dodecylbenzene sulfonic acid (sodium salt); polyoxyalkylene alkyl ether sulfonic acids (salts) such as polyoxyethylene 2-ethylhexyl ether sulfonic acid (potassium salt); stearoyl methyl tau higher fatty acid amide sulfonic acids (salts) such as sodium lauroyl methyl taurine, sodium myristoyl methyl taurine, and sodium palmitoyl methyl taurine; N-acyl sarcosinic acids (salts) such as sodium lauroyl sarcosinate; alkyl sulfates (salts) such as 2-ethylhexyl sulfate (sodium salt); polyoxyalkylene sulfates (salts) such as polyoxyethylene 2-ethylhexyl ether sulfate (sodium salt); long-chain sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate and sodium dioctyl sulfosuccinate; and long-chain N-acyl glutamates such as sodium N-lauroyl glutamate and disodium N-stearoyl-L-glutamate.

[0021] Cationic surfactants are surfactants that have at least one cationic group, such as an amino ether group, a quaternary ammonium group, a primary amine group, a secondary amine group, a tertiary amine group, an imidazolium base, or a pyridinium base.

[0022] Examples of cationic surfactants include alkyl quaternary ammonium salts such as lauryl trimethyl ammonium chloride, myristyl trimethyl ammonium chloride, palmityl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, oleyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, coconut oil alkyl trimethyl ammonium chloride, beef tallow alkyl trimethyl ammonium chloride, stearyl trimethyl ammonium bromide, coconut oil alkyl trimethyl ammonium bromide, cetyl trimethyl ammonium methosulfate, oleyl dimethyl ethyl ammonium ethosulfate, dioctyl dimethyl ammonium chloride, dilauryl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, and octadecyl diethyl methyl ammonium sulfate; (Polyoxyalkylene) alkylamino ether salts such as (polyoxyethylene) lauryl amino ether lactate, stearyl amino ether lactate, di(polyoxyethylene) lauryl methyl amino ether dimethyl phosphate, di(polyoxyethylene) lauryl ethyl ammonium ethosulfate, di(polyoxyethylene) hardened beef tallow alkyl ethyl amine ethosulfate, di(polyoxyethylene) lauryl methyl ammonium dimethyl phosphate, di(polyoxyethylene) stearyl amine lactate; acyl amido alkyl quaternary ammonium salts such as N-(2-hydroxyethyl)-N,N-dimethyl-N-stearoyl amido propyl ammonium nitrate, lanolin fatty acid amido propyl ethyl dimethyl ammonium ethosulfate, lauroyl amido ethyl methyl diethyl ammonium methosulfate; alkyl ethenoxy quaternary ammonium salts such as dipalmityl polyethenoxyethyl ammonium chloride, distearyl polyethenoxymethyl ammonium chloride; alkyl isoquinolinium salts such as lauryl isoquinolinium chloride; benzalkonium salts such as lauryl dimethyl benzyl ammonium chloride and stearyl dimethyl benzyl ammonium chloride;benzethonium salts such as benzyldimethyl{2-[2-(p-1,1,3,3-tetramethylbutylphenoxy)ethoxy]ethyl}ammonium chloride; pyridinium salts such as cetylpyridinium chloride; imidazolinium salts such as oleylhydroxyethylimidazolinium ethosulfate and laurylhydroxyethylimidazolinium ethosulfate; acyl basic amino acid alkyl ester salts such as N-cocoylarginine ethyl ester pyrrolidone carboxylate and N-lauroyllysine ethyl ester chloride; primary amine salts such as laurylamine chloride, stearylamine bromide, hardened beef tallow alkylamine chloride and rosinamine acetate; secondary amine salts such as cetylmethylamine sulfate, laurylmethylamine chloride, dilaurylamine acetate, stearylethylamine bromide, laurylpropylamine acetate, dioctylamine chloride and octadecylethylamine hydroxide; Examples of the tertiary amine salts include dilaurylmethylamine sulfate, lauryldiethylamine chloride, laurylethylmethylamine bromide, diethanolstearylamidoethylamine trihydroxyethylphosphate salt, and stearylamidoethylethanolamine urea polycondensate acetate salt; fatty acid amide guanidinium salts; and alkyltrialkyleneglycolammonium salts such as lauryltriethyleneglycolammonium hydroxide.

[0023] Amphoteric surfactants are surfactants that have at least one anionic group and at least one cationic group.

[0024] Examples of amphoteric surfactants include alkylphosphonic acids (salts) such as octylphosphonate (potassium salt); aromatic phosphonic acids (salts) such as phenylphosphonate (potassium salt); alkylphosphonic acid alkyl phosphate esters (salts) such as 2-ethylhexylphosphonate mono 2-ethylhexyl ester (potassium salt); and nitrogen-containing alkylphosphonic acids (salts) such as aminoethylphosphonic acid (diethanolamine salt).

[0025] The nonionic surfactant is a surfactant having at least one polyoxyalkylene group, fatty acid ester group, or the like.

[0026] Examples of nonionic surfactants include: polyoxyalkylene linear alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene cetyl ether; polyoxyalkylene branched primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, and polyoxyethylene isostearyl ether; polyoxyalkylene branched secondary alkyl ethers such as polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-octylhexyl ether, polyoxyethylene 1-hexyloctyl ether, polyoxyethylene 1-pentylheptyl ether, and polyoxyethylene 1-heptylpentyl ether; polyoxyalkylene alkenyl ethers such as polyoxyethylene oleyl ether; polyoxyalkylene alkyl phenyl ethers such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene dodecylphenyl ether; Polyoxyalkylene alkylarylphenyl ethers such as polyoxyethylene tristyrylphenyl ether, polyoxyethylene distyrylphenyl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene tribenzylphenyl ether, polyoxyethylene dibenzylphenyl ether, and polyoxyethylene benzylphenyl ether; polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene monomyristate, polyoxyethylene dilaurate, polyoxyethylene diolate, polyoxyethylene dimyristate, and polyoxyethylene distearate; sorbitan esters such as sorbitan monopalmitate and sorbitan monooleate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; glycerin fatty acid esters such as glycerin monostearate, glycerin monolaurate, and glycerin monopalmitate;Examples include polyoxyalkylene castor oil ethers such as polyoxyalkylene sorbitol fatty acid esters, sucrose fatty acid esters, and polyoxyethylene castor oil ether; polyoxyalkylene hydrogenated castor oil ethers such as polyoxyethylene hydrogenated castor oil ether; polyoxyalkylene alkylamino ethers such as polyoxyethylene lauryl amino ether and polyoxyethylene stearyl amino ether; oxyethylene-oxypropylene block or random copolymers; terminal alkyl etherified products of oxyethylene-oxypropylene block or random copolymers; and terminal sucrose etherified products of oxyethylene-oxypropylene block or random copolymers.

[0027] The oil may contain other organic components in addition to the oil (low polarity oil and / or high polarity oil) and / or surfactant described above. Examples of other organic components include antioxidants, viscosity modifiers, preservatives, etc. The content of other organic components is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, based on the total amount of the oil. The lower limit of the content of other organic components may be 0% by mass or more.

[0028] In a preferred embodiment, the ratio of the amount of oil (preferably a low-polarity oil) to the amount of surfactant contained in the oil agent (mass of oil:mass of surfactant) is preferably 30:1 to 1:10, more preferably 20:1 to 1:5, even more preferably 15:1 to 1:1, and still more preferably 10:1 to 2:1.

[0029] In a preferred embodiment, the oil agent has properties such that, when mixed with water to a solids concentration (non-volatile component concentration) of 25 mg / L, the average particle size of the oil agent in the resulting diluted solution (preferably an oil-in-water dispersion) is preferably 0.1 to 800 nm, more preferably 1 to 500 nm, even more preferably 10 to 300 nm, and even more preferably 20 to 200 nm. The diluted solution is a dispersion obtained by mixing the oil agent and water to a non-volatile component concentration of 25 mg / L, and stirring the mixture at 25°C and 120 rpm with a magnetic stirrer for 5 minutes.

[0030] (Bundling Yarn) The bundling yarn of the present invention contains at least fibers, a sizing agent (a water-soluble resin), and a specific amount or more of an oil agent, and the sizing agent and the oil agent are preferably present on the fiber surface in a mixed state. In this specification, "mixed state" does not mean a state in which the sizing agent and the oil agent are layered in order from the fiber surface, or in the reverse order, but rather a state in which the sizing agent and the oil agent are present randomly on the fiber surface, i.e., a state in which both the sizing agent and the oil agent are exposed in the form of a bundling yarn, rather than a state in which the sizing agent and the oil agent are present in a layered fibrous form, one hidden by the other. It is extremely difficult to determine whether the oil agent and the sizing agent are present in a mixed state on the fiber surface. However, the presence of the oil agent and the sizing agent in a mixed state allows the bundling yarn of the present invention to achieve the fiber cohesion degree (B / (A+B+C)) and fiber defibration degree (C / (A+C)) described below. The mixed state of the sizing agent and the oil agent contained in the bundling yarn can produce a molded product with little variation in toughness.

[0031] The fiber content in the bundle yarn is preferably 85 to 99.5% by mass, more preferably 88 to 99% by mass, and particularly preferably 90 to 98% by mass, relative to the total mass of the bundle yarn. If the fiber content is within the above range, when the bundle yarn is kneaded with a hydraulic material such as cement and water, it is easy to achieve rapid fiber defibration, it is easy to improve the fiber defibration degree of the bundle yarn, it is easy to prevent entanglement of the defibrated fibers, and it is easy to improve the strength of the molded body.

[0032] The content of the oil in the bundle yarn is preferably 0.05 to 4.0% by mass, more preferably 0.08 to 3.0% by mass, and particularly preferably 0.10 to 2.0% by mass, relative to the total mass of the bundle yarn. When the content of the oil is within the above range, the fiber cohesion degree (B / (A+B+C)) and fiber defibration degree (C / (A+C)) described below are easily achieved, and a molded product with high toughness is easily obtained.

[0033] The amount of oil per unit surface area of ​​the fiber in the bundle yarn is 5 mg / m ２ The content of the oil per unit surface area of ​​the fiber is 5 mg / m or more. ２If the thickness is less than 1 / 2 mm, the sizing agent (water-soluble resin) cannot be dispersed uniformly as small domains on the fiber surface, preventing rapid defibration. Furthermore, in a molded product obtained by hardening a hydraulic composition containing the sizing yarn, when cracks or the like occur in the molded product, it may be impossible to maintain an appropriate adhesive state between the fiber and the cement matrix, and the toughness of the molded product may not be improved.

[0034] The content of the oil agent per unit surface area of ​​the fibers contained in the bundle yarn is 5 mg / m from the viewpoint of easily increasing the toughness of the molded body. ２ or more, preferably 10 mg / m ２ More preferably, 15 mg / m ２ More preferably, 20 mg / m ２ or more, and even more preferably 30 mg / m ２ More preferably, 40 mg / m ２ More preferably, 50 mg / m ２ or more, most preferably 60 mg / m ２ More preferably, 70 mg / m ２ In addition, the content of the oil agent is preferably 500 mg / m from the viewpoint of the defibration property of the bundle yarn. ２ or less, more preferably 300 mg / m ２ More preferably, 240 mg / m ２ or less, and even more preferably 150 mg / m ２ Below 100 mg / m particularly preferably ２ Below 80 mg / m, particularly more preferably ２ From the same viewpoint, the content of the oil per unit surface area of ​​the fibers contained in the bundle yarn is preferably 5 to 500 mg / m ２ , more preferably 10 to 500 mg / m ２ , more preferably 15 to 300 mg / m ２ , and even more preferably 20 to 300 mg / m ２ , particularly preferably 30 to 240 mg / m ２ , and particularly preferably 40 to 240 mg / m ２ , most preferably 50 to 150 mg / m ２ , most preferably 60 to 100 mg / m２ , particularly preferably 70 to 80 mg / m ２ The oil content per unit surface area of ​​the fiber (mg / m ２ The content of the oil agent is calculated from the content of the fibers, sizing agent, and organic components other than inorganic substances contained in the bundle yarn.

[0035] The content of oil per unit surface area of ​​the fiber (mg / m ２ ) is represented by formula (1'): [In the formula, W Ｏ represents the weight of oil per weight of fiber (mass%), T represents the fiber fineness (dtex), and ρf represents the fiber density (g / cm ３ ) is calculated as follows.

[0036] If the calculation cannot be performed using the above formula (1'), it can be performed as follows. First, the fiber fineness represents the weight per 10,000 m of fiber, and this fineness is designated as T (dtex). Then, the weight of the oil agent per weight of fiber is designated as W. Ｏ (mass%), the weight of oil per 10,000 m of fiber is T x W Ｏ If the perimeter of the cross section of the fiber is L cm, the surface area per 10,000 m of fiber is L x 10 ６ (cm ２ The oil content per unit surface area of ​​the fiber (mg / cm ２ ) is expressed by the following formula (1): The value obtained is calculated by 10 ４ By multiplying this, the oil content per unit surface area of ​​the fiber (mg / m ２ It is preferable to add the oil in an amount such that the amount of oil per unit surface area of ​​the fiber falls within the above range.

[0037] The method for calculating the circumferential length L (cm) of the cross section of the fiber varies depending on the shape of the fiber, and can be calculated according to the shape of the fiber used. For example, if the cross section of the fiber is close to a perfect circle, and the diameter of the fiber is D (cm), the diameter D (cm) of the fiber is calculated by multiplying the fiber density ρf (g / cm ３ ) and fineness T (dtex) to obtain the formula: Therefore, when the cross section of the fiber is nearly a perfect circle, the circumferential length L (cm) is calculated by the formula: [wherein T represents the fiber fineness (dtex), ρf represents the fiber density (g / cm ３ ) represents the circumference L cm, and the calculated value is substituted into the above formula (1) to obtain the content of oil per unit surface area of ​​the fiber (mg / m ２ ) is calculated. If the diameter of the fiber is D (cm), the cross-sectional area of ​​the fiber is π × D ２ / 4 (cm ２ ) where the fiber density is expressed as ρf (g / cm ３ ), the fiber volume per 10,000 m is T / ρ ｆ (cm ３ / 10000m), then the fiber cross-sectional area is T / ρ ｆ x10 －６ (cm ２ ) Therefore, T / ρ ｆ x10 －６ = π × D ２ / 4, D is calculated by the above formula. Therefore, the content of oil per unit surface area of ​​the fiber in this case (mg / m ２ ) is represented by formula (1'): It can also be expressed as:

[0038] The cross section of the fiber may be circular or may have a non-circular irregular shape, such as flat, elliptical, cross, T-shaped, Y-shaped, L-shaped, triangular, square, or star-shaped. The surface area of ​​these fibers can be calculated by calculation, as with the above-mentioned circular shape, if the perimeter of the fiber cross section can be calculated. If the fiber shape is complex, the surface area of ​​the fiber can be calculated, for example, by measuring the surface area from the amount of gas adsorbed by gas adsorption.

[0039] The content of the water-soluble resin in the bundle yarn is preferably 0.01 to 1.0 mass%, more preferably 0.02 to 0.5 mass%, and particularly preferably 0.03 to 0.3 mass%, relative to the total mass of the bundle yarn. If the content of the water-soluble resin is equal to or greater than the above-mentioned lower limit, fiber defibration is easily suppressed when the hydraulic material and the bundle yarn are mixed in a dry state, and as a result, damage to the fibers is easily prevented. On the other hand, if the content is equal to or less than the above-mentioned upper limit, the degree of fiber defibration is easily improved when the bundle yarn is kneaded with the hydraulic material and water.

[0040] The content of the water-soluble resin per unit surface area of ​​the fiber in the bundle yarn is preferably 1.5 mg / m from the viewpoint of suppressing the generation of fiber balls and from the viewpoint of easily increasing the toughness of the molded body. ２ More preferably, 2.0 mg / m ２ or more, more preferably 3.0 mg / m ２ or more, for example, 4 mg / m ２ Above, 10mg / m ２ Above, 15mg / m ２ Above, 20mg / m ２ In addition, the content of the water-soluble resin is preferably 200 mg / m from the viewpoint of easily improving the defibration property of the bundle yarn. ２ or less, more preferably 100 mg / m ２ More preferably, 50 mg / m ２ or less, for example, 30 mg / m ２ The content of the water-soluble resin per unit surface area of ​​the fiber (mg / m ２ ) is the mass of oil per mass of fiber in the above formula (1) that calculates the content of oil per unit surface area of ​​fiber, W Ｏ (mass%), the mass W of the water-soluble resin per mass of the fiber ｒ (mass%), the following formula (2): It is calculated as follows.

[0041] The ratio (Y / X) of the oil content (Y% by mass) based on the total amount of the bundle yarn to the water-soluble resin content (X% by mass) based on the total amount of the bundle yarn may be in the range of 0.5 to 15, preferably 1 to 15, more preferably 1 to 12, and even more preferably 1.5 to 8, from the viewpoint of easily improving the defibration ability of the bundle yarn and easily increasing the toughness of the molded body, and may also be 1.5 to 4.5, 1.5 to 3.5, or 1.5 to 2.5. In a preferred embodiment, it may be in the range of 2.5 to 4.5. The oil content (Y% by mass) based on the total amount of the bundle yarn to the water-soluble resin content (X% by mass) based on the total amount of the bundle yarn can be measured by the method described in the Examples.

[0042] The fiber cohesion degree (B / (A+B+C)) of the bundle yarn of the present invention is preferably 0.20 or less, more preferably 0.15 or less, and even more preferably 0.10 or less. In this specification, the fiber cohesion degree (B / (A+B+C)) is the mass ratio of the mass A (g) of the bundle yarn remaining on the sieve, the mass B (g) of the fiber balls remaining on the sieve, and the mass C (g) of the defibrated fibers that fall through the sieve, when the aggregate, cement, and bundle yarn are dry-mixed for 90 seconds, water is added, and the mixture is further mixed for 60 seconds. Specifically, it can be determined by the method described in the examples.

[0043] The fiber defibration degree (C / (A+C)) of the bundle yarn of the present invention is preferably 0.80 or more, more preferably 0.90 or more, and even more preferably 0.95 or more. The fiber defibration degree (C / (A+C)) in this specification can be determined from the mass A (g) of the bundle yarn remaining on the sieve and the mass C (g) of the defibrated fibers that have fallen through the sieve, which are obtained by the same measurement method as for the fiber cohesion degree.

[0044] The length of the bundle thread of the present invention is not particularly limited, but is preferably 1 to 60 mm, more preferably 1 to 50 mm, even more preferably 1 to 40 mm, even more preferably 2 to 30 mm, and particularly preferably 3 to 20 mm. If the length of the bundle thread is within the above range, it is less likely to become fiber balls during kneading, and a molded product with high toughness is more likely to be obtained. Furthermore, if high fluidity is required for the kneaded product, it is more preferable that the length be less than 10 mm.

[0045] <Method for Producing Bundle Yarn> The method for producing the fibers contained in the bundle yarn of the present invention is not particularly limited, and general melt spinning, solution spinning, dry spinning, etc. can be used. The fibers contained in the bundle yarn of the present invention can be produced, for example, by the following method. For example, when the fibers are PVA-based fibers, a vinyl alcohol-based polymer is formed into aqueous chips with a concentration of 40 to 60% by mass, heated and dissolved in an extruder, and degassed to form a spinning solution. A crosslinking agent is then added to this spinning solution. Examples of crosslinking agents include ammonium sulfate, sulfuric acid, ammonium phosphate, phosphoric acid, hydrochloric acid, nitric acid, acetic acid, and oxalic acid. However, ammonium sulfate is preferred because it does not corrode pipes, does not emit a foul odor, and does not foam the fibers. The amount of crosslinking agent added is preferably 0.5 to 10% by mass relative to the mass of the vinyl alcohol-based polymer. The temperature of the spinning solution is preferably 90 to 140°C. The spinning solution to which such a crosslinking agent has been added is pressurized and discharged into the air through a nozzle hole, and dry-spinned. The nozzle hole may be circular or may have a shape other than circular, such as flat, cross, T-shaped, Y-shaped, L-shaped, triangular, square, or star-shaped.

[0046] Next, the spun fibers are dried. The drying temperature is usually 100°C or lower in the initial stage of drying, and once drying has progressed to a certain extent, the fibers are preferably completely dried at a temperature of 100°C or higher.

[0047] After drying, the fiber is stretched and heat-treated. The stretching is usually carried out at a stretching temperature of 200 to 250°C, preferably 220 to 240°C. The stretching ratio is usually 5 times or more, preferably 6 times or more. The stretching is carried out in a hot air stretching oven for about 20 seconds to 3 minutes. The stretched fiber is optionally heat-treated to achieve a fixed length or shrinkage. The fiber thus obtained may be crimped as needed. When the fiber is a polyvinyl alcohol-based fiber, a crosslinking agent added to the spinning dope reacts with the OH groups of the polyvinyl alcohol during stretching, resulting in crosslinking.

[0048] Next, a water-soluble resin (sizing agent) and an oil agent are applied to the resulting fibers. While there are no particular limitations on the method for applying the sizing agent and oil agent to the fiber surface, from the perspective of easily and uniformly applying the sizing agent and oil agent to the fibers, applying them in the form of a liquid containing the sizing agent and oil agent is preferred. Applying them in the form of an oil-in-water dispersion in which the oil agent is dispersed in an aqueous solution of the sizing agent is more preferred. Applying them in the form of an oil-in-water dispersion in which all or at least a portion of the oil agent is present in the form of micelles or emulsions is even more preferred. In this specification, "micelles" refers to particles formed by the aggregation of surfactants contained in the oil agent of the present invention, and "emulsion" refers to particles in which oil is trapped inside the micelles of the surfactant. The oil-in-water dispersion can be obtained by any known method, such as using a dissolver with a stirrer or an ultrasonic dissolver.

[0049] In a preferred embodiment, the present invention also provides a method for producing a bundled yarn containing a plurality of fibers, the method comprising: (Step 1) adhering an oil-in-water dispersion containing a sizing agent that is a water-soluble resin, an oil agent, and water to a fiber surface. The method may further comprise: (Step 2) drying the fibers obtained in Step 1 in a bundled state.

[0050] The average particle size of the dispersed particles contained in the oil-in-water dispersion is preferably 1 to 500 nm, more preferably 5 to 400 nm, even more preferably 10 to 300 nm, and even more preferably 50 to 200 nm. The average particle size of the dispersed particles contained in the oil-in-water dispersion can be adjusted by the amount of sizing agent and oil agent contained in the oil-in-water dispersion, the ratio of oil in the oil agent, the pH of the oil-in-water dispersion, the stirring speed and stirring time when preparing the oil-in-water dispersion, and the like, and can be measured by the method described in the Examples. When the average particle size of the dispersed particles contained in the oil-in-water dispersion is within the above range, the converged state can be maintained even when shear stress is applied in the absence of water, and a convergent yarn that is easily defibrated in the presence of water can be easily obtained. The average particle size of the dispersed particles can be measured using a particle size measuring device (e.g., the "ELS-Z" (manufactured by Otsuka Electronics Co., Ltd.)). The present invention also provides a convergent yarn produced by the above-mentioned production method of the present invention.

[0051] The concentrations of the sizing agent and oil in the dispersion can be set appropriately depending on the equipment used, the desired content of the sizing agent and oil, the viscosity of the solution, etc. However, when the sizing agent and oil are applied to the fiber surface using a liquid containing the sizing agent and oil, from the viewpoint of removing the liquid (e.g., water) by drying after application, the oil content in the dispersion is preferably about 5 to 200 g / L, more preferably about 8 to 150 g / L, and even more preferably about 10 to 100 g / L. The sizing agent content in the dispersion is also preferably about 0.5 to 100 g / L, more preferably about 1.0 to 50 g / L, and even more preferably about 2.0 to 30 g / L.

[0052] The amount of water in the dispersion is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on the total amount of the dispersion.

[0053] The oil-in-water dispersion described above is a composition suitable for use as an aqueous sizing composition. Accordingly, in a preferred embodiment, the present invention also provides an aqueous sizing composition comprising a sizing agent that is a water-soluble resin, an oil agent, and water, wherein the water content is 80 mass % or more based on the total amount of the aqueous sizing composition, the aqueous sizing composition is an oil-in-water dispersion, and the average particle size of the dispersed particles is 1 to 500 nm. The above descriptions regarding the oil-in-water dispersion also apply to the aqueous sizing composition.

[0054] The method for applying the dispersion to the fiber surface is not particularly limited, and known methods such as immersion, dipping, spraying, and coating can be used. For example, coating can be performed by roller touch, coronoid, etc. The bundled yarn of the present invention is obtained by drying a plurality of fibers to which a liquid containing a sizing agent and an oil has been applied, while the fibers are bundled together. The drying conditions are not particularly limited, and the temperature and time can be appropriately set so that the liquid used volatilizes. The bundled yarn of the present invention may also be produced by adding other components to the liquid containing the sizing agent and an oil.

[0055] The present invention also provides a focusing thread produced using an oil agent in an oil-in-water dispersion having a solids concentration of 25 mg / L, the average particle size of which is 0.1 to 800 nm. This oil agent is the same as that described for the focusing thread of the present invention, and the same description of this oil agent applies. This oil agent has properties such that, when mixed with water to a solids concentration (non-volatile component concentration) of 25 mg / L, the average particle size of the oil agent in the resulting diluted solution (preferably an oil-in-water dispersion) is preferably 0.1 to 800 nm, more preferably 1 to 500 nm, even more preferably 10 to 300 nm, and even more preferably 20 to 200 nm. The diluted solution is a dispersion obtained by mixing the oil agent and water to a non-volatile component concentration of 25 mg / L, and stirring the mixture at 120 rpm at 25°C for 5 minutes using a magnetic stirrer. Furthermore, the bundle yarn produced using the oil agent is preferably a bundle yarn produced using the above-mentioned aqueous sizing composition containing the oil agent.

[0056] The bundle yarn of the present invention is usually a bundle yarn cut to a desired fiber length. The cutting method is not particularly limited, and examples thereof include side cutting, water jet cutting, laser cutting, disk blade cutting, ultrasonic cutting, and scissors cutting. Among these, the side cutting, laser cutting, and water jet cutting methods are preferred from the viewpoint of easily suppressing damage to the fiber ends.

[0057] (Sizing Agent) The sizing agent contained in the sizing yarn of the present invention is a water-soluble resin. In this specification, the water-soluble resin is a resin having a solubility of 9 g / L or more in alkaline water of pH 12 at room temperature (20°C). In other words, when 2 parts by mass of the water-soluble resin is added to 100 parts by mass of alkaline water of pH 12 and stirred at 20°C for 5 minutes, preferably 45% by mass or more of the water-soluble resin dissolves. This solubility is also referred to as "alkali solubility." Specifically, the solubility may be evaluated by placing 2 parts by mass of a film (approximately 50 μm thick and approximately 1 cm square) of the water-soluble resin in 100 parts by mass of alkaline water of pH 12 at 20°C and stirring at a stirring speed of 500 rpm for 5 minutes, and measuring the mass of the water-soluble resin dissolved.

[0058] The alkali solubility of the water-soluble resin is preferably 10 g / L or more, more preferably 12 g / L or more, even more preferably 14 g / L or more, and especially preferably 16 g / L or more from the viewpoint of easily improving the defibration ability of the bundle yarn and easily improving the toughness of the molded body, and is preferably 50 g / L or less, more preferably 45 g / L or less, even more preferably 40 g / L or less, still more preferably 20 g / L or less, especially preferably 19 g / L or less, and especially preferably 18 g / L or less from the viewpoint of easily improving the convergence ability of the fiber and easily preventing the occurrence of buckling portions, etc. The alkali solubility is the amount of water-soluble resin dissolved when a film-like water-soluble resin is added to alkaline water of pH 12 (e.g., alkaline water adjusted to pH 12 with sodium hydroxide) and stirred at room temperature (20°C). For example, when 2 parts by mass of the water-soluble resin is added to 100 parts by mass of alkaline water of pH 12 and stirred at 20° C. for 5 minutes, preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass of the resin dissolves. Therefore, the alkali solubility of the water-soluble resin is preferably 10 to 50 g / L, more preferably 12 to 40 g / L, even more preferably 14 to 20 g / L, even more preferably 16 to 19 g / L, and particularly preferably 16 to 18 g / L.

[0059] The water-soluble resin preferably has a lower neutral solubility (solubility when water of pH 7 is used instead of alkaline water under the same conditions as alkaline solubility) than alkaline solubility. The difference between alkaline solubility and neutral solubility (alkaline solubility - neutral solubility) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The greater the difference between neutral solubility and alkaline solubility, the more effectively the convergence of the yarn can be suppressed due to a humid environment, rain, etc.

[0060] The water-soluble resin is not particularly limited as long as it is a resin having the above-mentioned solubility, and examples thereof include polyvinyl alcohol-based resins (resins containing structural units derived from vinyl alcohol), ethyleneimine-based resins (resins containing structural units derived from ethyleneimine), acrylic resins, urethane resins, and epoxy resins.

[0061] From the viewpoint of solubility in the cement matrix, the water-soluble resin is preferably a resin selected from the group consisting of polyvinyl alcohol-based resins, ethyleneimine-based resins, acrylic-based resins, and epoxy resins, and more preferably a resin selected from the group consisting of polyvinyl alcohol-based resins, ethyleneimine-based resins, and acrylic-based resins.

[0062] The water-soluble resin is more preferably a vinyl alcohol resin containing structural units derived from vinyl alcohol, and even more preferably a modified polyvinyl alcohol.

[0063] In a preferred embodiment of the present invention, the water-soluble resin is a modified polyvinyl alcohol, which has a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof. The amount of the structural unit (X) is preferably 0.1 to 10 mol % when the amount of all monomer units of the modified polyvinyl alcohol is taken as 100 mol %. The degree of saponification of the modified polyvinyl alcohol is preferably 85 mol % or more. The modified polyvinyl alcohol refers to a polyvinyl alcohol modified with a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof, and the modified polyvinyl alcohol has at least a structural unit derived from vinyl alcohol and a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof. The modified polyvinyl alcohol may contain structural units other than the above structural units.

[0064] The amount of the structural unit (X) is more preferably 0.5 to 10 mol %, even more preferably 1 to 9.5 mol %, and even more preferably 2 to 9 mol %, from the viewpoints of easily increasing the fiber defibration degree of the bundle yarn, easily decreasing the degree of aggregation of the defibrated fibers, and easily increasing the reinforcing effect of the fiber on the molded article. Note that the amount of the structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof contained in the modified polyvinyl alcohol is preferably 0.5 to 10 mol %, even more preferably 1 to 9.5 mol %, and even more preferably 2 to 9 mol %. １ It can be determined from the H-NMR peak.

[0065] The degree of saponification of polyvinyl alcohol is preferably 85 mol% or more, more preferably 88 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 98 mol% or more, from the viewpoint of easily sufficiently increasing the solubility of polyvinyl alcohol in water. The upper limit of the degree of saponification may be 100 mol% or less, and from the viewpoint of improving the solubility in water by reducing the crystallinity of polyvinyl alcohol, it is preferably 99.9 mol% or less, more preferably 99.8 mol% or less. Therefore, the degree of saponification of polyvinyl alcohol is preferably 85 mol% to 100 mol%, more preferably 88 mol% to 100 mol%, even more preferably 90 mol% to 99.9 mol%, even more preferably 95 mol% to 99.9 mol%, and particularly preferably 98 mol% to 99.8 mol%. The degree of saponification can be measured by the method described in JIS K 6726:1994.

[0066] The viscosity-average degree of polymerization of polyvinyl alcohol is preferably 100 to 5,000, more preferably 100 to 4,000, and even more preferably 300 to 3,500. When the viscosity-average degree of polymerization is equal to or greater than the above-mentioned lower limit, the fiber sizing ability as a sizing agent is easily improved. When the viscosity-average degree of polymerization is equal to or less than the above-mentioned upper limit, the solubility of polyvinyl alcohol in water can be improved, and rapid and sufficient defibration of fibers is easily achieved. The viscosity-average degree of polymerization can be measured by the method described in JIS K 6726:1994. Specifically, when the saponification degree is less than 99.5 mol%, the viscosity-average degree of polymerization (P) can be calculated by the following formula using the intrinsic viscosity [η] (liters / g) measured in water at 30°C for PVA saponified to a saponification degree of 99.5 mol% or more: P=([η]×10 ４ / 8.29) （１／０．６２）

[0067] Examples of unsaturated carboxylic acids that provide the structural unit (X) contained in the modified polyvinyl alcohol include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, phthalic acid, maleic acid, and itaconic acid. Derivatives of these include alkyl esters and metal salts of the above-mentioned ethylenically unsaturated carboxylic acids. The modified polyvinyl alcohol used as a sizing agent may have one type of structural unit, two or more types of structural units, or additional structural units as the structural unit (X) derived from the unsaturated carboxylic acid or a derivative thereof.

[0068] The unsaturated carboxylic acid or its derivative is preferably at least one selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid alkyl esters, and (meth)acrylic acid metal salts, from the viewpoint of easily increasing the fiber defibration degree of the bundle yarn and easily reducing the degree of aggregation of the defibrated fibers. Note that the term "(meth)acrylic" used in this specification means "acrylic and / or methacrylic."

[0069] Examples of (meth)acrylic acid alkyl esters include esters of (meth)acrylic acid with linear or branched alcohols having 1 to 5 carbon atoms, and specific examples include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid butyl ester, and (meth)acrylic acid pentyl ester. Examples of metal salts of (meth)acrylic acid include alkali metal salts of (meth)acrylic acid. Examples of alkali metal elements include lithium, sodium, and potassium.

[0070] In a preferred embodiment of the present invention, the modified polyvinyl alcohol used as a sizing agent typically contains at least a plurality of structural units derived from vinyl alcohol as a monomer and a plurality of structural units (X) derived from an unsaturated carboxylic acid or a derivative thereof. The amount of the structural units (X) derived from the unsaturated carboxylic acid or a derivative thereof is 0.1 to 10 mol % when the amount of all monomer units is taken as 100 mol %. Considering the above molar ratio, it is believed that the majority of the structural units (X) derived from the unsaturated carboxylic acid or a derivative thereof contained in the modified polyvinyl alcohol are present adjacent to the structural units derived from vinyl alcohol. In this case, the structural units (X) and the structural units derived from vinyl alcohol may exist as separate structural units (monomer units), or at least a portion of the structural units (X) may be present as ring-closed structural units with hydroxyl groups contained in adjacent structural units derived from vinyl alcohol.

[0071] In addition, a structural unit formed by ring closure between, for example, a carboxyl group contained in a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof and a hydroxyl group contained in a structural unit derived from vinyl alcohol is also a structural unit containing the structural unit (X) and is a structural unit derived from an unsaturated carboxylic acid or a derivative thereof. Herein, when calculating the amount of all monomer units of a modified polyvinyl alcohol, the ring-closed structural unit is not considered to be one structural unit, but the structural unit (X) before ring closure and the structural unit derived from vinyl alcohol, which are structural units corresponding to the monomer, are considered to be separate monomer units.

[0072] In a preferred embodiment of the present invention, the modified polyvinyl alcohol contained in the sizing agent has a structural unit (X) derived from an unsaturated carboxylic acid or its derivative, and / or a structural unit in which the structural unit (X) is cyclically linked to an adjacent structural unit derived from vinyl alcohol. When polyvinyl alcohol is modified with a structural unit (X) derived from an unsaturated carboxylic acid or its derivative, the modified polyvinyl alcohol exhibits excellent sizing agent performance, particularly fiber sizing, when not dissolved in water. This facilitates preventing fiber damage when dry-mixing the sizing yarn with a hydraulic material. Polyvinyl alcohol modified with the structural unit (X) has high solubility in water due to carboxyl groups, etc., and a sizing yarn containing such a modified polyvinyl alcohol as a sizing agent is characterized by the rapid dissolution of the sizing agent when mixed with water, resulting in rapid and sufficient fiber defibration. Regarding the required speed of defibration, the required speed may vary depending on the amount of sizing yarn used, the application of the hydraulic material, etc., but the examples in this specification evaluate defibration performance when kneaded for a very short time, for example, on the order of a few minutes.

[0073] In particular, when the modified polyvinyl alcohol has a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof, and / or a structural unit formed by ring-closing the structural unit (X) with an adjacent structural unit derived from vinyl alcohol, the solubility of the modified polyvinyl alcohol in water is very low in the ring-closed state, and therefore the performance as a sizing agent is excellent and fiber damage during dry mixing is easily suppressed. Such a closed-ring structure has a very high ring-opening property when dissolved in water, particularly in an alkaline environment, and the modified polyvinyl alcohol having the structural unit (X) after ring-opening has high solubility in water. Therefore, a sizing yarn containing such a modified polyvinyl alcohol as a sizing agent is characterized in that the sizing agent dissolves rapidly when mixed with water in an alkaline environment, making it easy to achieve rapid and sufficient fiber defibration.

[0074] In a preferred embodiment of the present invention, the modified polyvinyl alcohol contains a structural unit (X) derived from an unsaturated carboxylic acid or a derivative thereof represented by the formula (X1): [in formula (X1), X is a hydrogen atom or a methyl group] and / or a structural unit represented by formula (X2): In formula (X2), X is a hydrogen atom or a methyl group, and Y is a hydrogen atom, an alkali metal atom, or an alkyl group having 1 to 5 carbon atoms.

[0075] The structural unit represented by formula (X2) is a structural unit derived from at least one selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid alkyl esters, and metal salts of (meth)acrylic acid, and when the structural unit (X2) undergoes ring closure with an adjacent structural unit derived from vinyl alcohol, it becomes the structural unit (X1). When a modified polyvinyl alcohol contains a structural unit represented by formula (X1) and / or a structural unit represented by formula (X2) as the structural unit (X), when the bundle yarn is kneaded with a hydraulic material such as cement and water, it is easy to achieve rapid defibration of the fibers, it is easy to improve the fiber defibration degree of the bundle yarn, and it is easy to prevent aggregation of the defibrated fibers.

[0076] The modified polyvinyl alcohol may contain one type of structural unit represented by formula (X1), or may contain two types of structural units represented by formula (X1). The modified polyvinyl alcohol may contain one type of structural unit represented by formula (X2), or may contain two or more types of structural units represented by formula (X2). The modified polyvinyl alcohol may contain one or more types of structural units represented by formula (X1) and one or more types of structural units represented by formula (X2).

[0077] When the modified polyvinyl alcohol contains a structural unit represented by formula (X1) and / or a structural unit represented by formula (X2), the ratio of the molar amount of the structural unit represented by formula (X1) to the total molar amount of the structural unit represented by formula (X1) and the structural unit represented by formula (X2) (X1 / (X1+X2)) is preferably 0.65 or more and 1.0 or less, more preferably 0.70 or more and 0.99 or less, even more preferably 0.85 or more and 0.99 or less, and particularly preferably 0.90 or more and 0.99 or less. When the content ratio of the structural unit represented by formula (X1) is equal to or more than the above lower limit, when the bundle yarn is kneaded with a hydraulic material such as cement and water, rapid fiber defibration is easily achieved, the fiber defibration degree of the bundle yarn is easily improved, and aggregation of the defibrated fibers is easily prevented. Note that the content (molar amount) of the structural unit (X1) and the structural unit (X2) contained in the modified polyvinyl alcohol is determined by the ratio of the molar amount of the modified polyvinyl alcohol. １ It can be determined from the H-NMR peak.

[0078] In a preferred embodiment of the present invention, the modified polyvinyl alcohol contains at least a structural unit represented by formula (X1). In this embodiment, the amount of the structural unit represented by formula (X1) is preferably 0.1 to 10 mol%, more preferably 0.5 to 10 mol%, more preferably 1 to 9.5 mol%, and particularly preferably 2 to 9 mol%, based on 100 mol% of the total amount of monomer units in the modified polyvinyl alcohol. When the amount of the structural unit represented by formula (X1) is within the above range, the performance as a sizing agent (e.g., fiber sizing ability) is easily improved, and fiber damage during dry mixing of the sizing yarn with a hydraulic material is easily suppressed. Furthermore, rapid and sufficient fiber defibration is easily achieved when the sizing yarn is mixed with water. As a result, the degree of fiber defibration of the sizing yarn is easily increased, fiber aggregation is easily suppressed, and the mechanical strength of the molded product is easily increased.

[0079] (Method for Producing Modified Polyvinyl Alcohol) Modified polyvinyl alcohol can be obtained by copolymerizing a vinyl ester monomer with a monomer having a carbonyl group (unsaturated carboxylic acid or a derivative thereof) by a known method, saponifying the resulting copolymer by a known method, and then subjecting the copolymer to a washing treatment and a heat treatment. Furthermore, modified polyvinyl alcohol can be efficiently obtained by neutralizing the saponified copolymer with an acid treatment, followed by a washing treatment and a heat treatment.

[0080] Examples of vinyl ester monomers used in the production of modified polyvinyl alcohol include vinyl acetate, vinyl propionate, and vinyl formate, with vinyl acetate being preferred from an economical standpoint. Furthermore, examples of monomers having a carbonyl group used in the production of modified polyvinyl alcohol include acrylic acid, methacrylic acid, and alkyl esters of these carboxylic acids. Suitable alkyl esters include methyl esters, ethyl esters, and the like. Suitable carboxylates obtained by partially or completely neutralizing these carboxylic acids and esters are also suitable. Vinyl monomers containing a lactone ring in the side chain may also be used.

[0081] Heat treatment is important in order to form a structural unit in which at least a portion of the structural units (X) are ring-closed with a hydroxyl group contained in an adjacent structural unit derived from vinyl alcohol. The method of heat treatment is not particularly limited, but it is preferable to use, for example, a hot air dryer, a rotary dryer, or the like. The heating temperature is preferably 60 to 150°C, more preferably 80 to 150°C. The heating time is preferably 1 to 10 hours, more preferably 2 to 8 hours. By the above heat treatment, for example, the ratio of the structural unit (X1) to the total amount of the structural unit (X1) and the structural unit (X2) can be adjusted to the above-mentioned predetermined range.

[0082] (Fibers) The fibers contained in the bundle yarn of the present invention are not particularly limited, but examples thereof include synthetic polymer fibers such as polyvinyl alcohol (hereinafter sometimes referred to as PVA) fibers, polyolefin fibers, polyamide fibers (including aramid fibers), acrylic fibers, polybenzoxazole fibers, polyester fibers, and rayon fibers (polynosic fibers, solvent-spun cellulose fibers, etc.), as well as metal fibers and glass fibers.

[0083] PVA-based fibers are fibers containing a vinyl alcohol-based polymer. From the viewpoints of mechanical performance, adhesion to hydraulic materials, and alkali resistance, the fibers preferably contain 30% by mass or more of the vinyl alcohol-based polymer, more preferably 60% by mass or more, and even more preferably 80% by mass or more. The fibers contained in the bundling yarn of the present invention are preferably PVA-based fibers, from the viewpoint of easily increasing the strength of the resulting molded body. When the fibers are PVA-based fibers, they are highly hydrophilic due to their molecular structure, and hydroxyl groups of the fibers bond with Ca in the cement, improving the affinity between the fibers and cement and increasing chemical adhesive strength. Furthermore, the area around the fibers is likely to have a calcium hydroxide-rich structure, which easily increases the frictional resistance between the fibers and cement.

[0084] The vinyl alcohol polymer constituting the PVA fiber may be a homopolymer of vinyl alcohol, or may be a copolymer of vinyl alcohol and other monomers, or may be modified, as long as the effects of the present invention are not impaired. From the viewpoint of easily improving the mechanical strength, alkali resistance, hot water resistance, etc. of the fiber, when the amount of all monomer units constituting the vinyl alcohol polymer is taken as 100 mol%, the total amount of structural units derived from optionally contained modified vinyl alcohol monomers and the amount of optionally contained monomers other than vinyl alcohol is preferably 30 mol% or less, more preferably 10 mol% or less.

[0085] The viscosity-average degree of polymerization of the vinyl alcohol polymer constituting the PVA fiber is preferably 1,000 or more, more preferably 1,500 or more, from the viewpoint of easily improving the mechanical strength, alkali resistance, and hot water resistance of the fiber. From the viewpoint of easily reducing the production cost of the vinyl alcohol polymer, the viscosity-average degree of polymerization is preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less. The method for measuring the viscosity-average degree of polymerization is as described above for polyvinyl alcohol.

[0086] The saponification degree of the vinyl alcohol polymer constituting the PVA fiber is preferably 99 mol% or more, more preferably 99.5 mol% or more, and even more preferably 99.8 mol% or more, from the viewpoints of heat resistance, durability, and dimensional stability of the fiber. The upper limit of the saponification degree is 100 mol% or less. The method for measuring the saponification degree is as described above for polyvinyl alcohol.

[0087] The fibers contained in the bundle yarn of the present invention may be fibers made of one type of polymer, or may be composite fibers made of two or more types of polymers. Examples of the shape of the composite fiber include an islands-in-sea type, a sheath-core type, and a side-by-side type.

[0088] The fiber length of the fibers contained in the bundle yarn of the present invention is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. For example, it may be 4 mm or more, 6 mm or more, or 8 mm or more. The fiber length is preferably 60 mm or less, more preferably 50 mm or less, even more preferably 40 mm or less, particularly preferably 30 mm or less, and especially preferably 20 mm or less. When the fiber length of the polyvinyl alcohol-based fiber is below the above-mentioned upper limit, entanglement of the fibers is further suppressed, and the dispersion of the fibers in the molded product of the hydraulic composition is further improved. Furthermore, the fiber has excellent followability to the expansion and contraction of the molded product of the hydraulic composition, thereby further improving the reinforcing performance of the hydraulic material. When the fiber length of the polyvinyl alcohol-based fiber is above the above-mentioned lower limit, the adhesion of the fiber to the hydraulic material is enhanced, and the reinforcing performance of the hydraulic material is further improved. The fiber length of the fibers contained in the bundle yarn is preferably 1 to 60 mm, more preferably 1 to 50 mm, even more preferably 1 to 40 mm, even more preferably 2 to 30 mm, and especially preferably 3 to 20 mm.

[0089] The aspect ratio of the fibers contained in the bundle yarn of the present invention is preferably 30 to 2,500, more preferably 35 to 2,000, even more preferably 40 to 1,000, even more preferably 40 to 500, and particularly preferably 40 to 300. When the aspect ratio is equal to or greater than the above-mentioned lower limit, the reinforcing effect of adding the fibers is easily enhanced. Furthermore, when the aspect ratio is equal to or less than the above-mentioned upper limit, entanglement of the defibrated fibers contained in the matrix containing the hydraulic material is easily suppressed, and the reinforcing performance of the hydraulic material is easily enhanced. Note that, in this specification, the aspect ratio refers to the ratio (L / D) of the fiber length (L) to the fiber diameter (D), and can be calculated by calculating the fiber length in accordance with JIS L1015:2021 "Test Methods for Chemical Fiber Staples (8.4)" and then calculating the ratio to the fiber diameter.

[0090] The average fiber diameter of the fibers contained in the bundle yarn of the present invention is preferably 3 to 900 μm, more preferably 4 to 800 μm, and even more preferably 5 to 700 μm. When the average fiber diameter of the fibers is equal to or greater than the above-mentioned lower limit, the reinforcing performance of the hydraulic composition in a molded article is easily improved, and the mechanical strength of the resulting molded article is easily increased. The average fiber diameter of the fibers can be calculated from the fineness and fiber density. The fineness of the fibers contained in the bundle yarn of the present invention is preferably 0.1 to 9,000 dtex, more preferably 0.15 to 7,000 dtex, even more preferably 0.25 to 5,000 dtex, and even more preferably 0.25 to 500 dtex. In a particularly preferred embodiment, the fineness may be 0.25 to 150 dtex, 0.25 to 100 dtex, 0.25 to 50 dtex, 0.25 to 20 dtex, or 0.25 to 10 dtex.

[0091] The tensile strength of the fiber contained in the bundle yarn of the present invention is preferably 5 cN / dtex or more, more preferably 8 cN / dtex or more, even more preferably 10 cN / dtex or more, and particularly preferably 11 cN / dtex or more. When the tensile strength of the fiber is at least the above lower limit, the reinforcing performance of the hydraulic composition for a molded body is easily improved, and the mechanical strength of the resulting molded body is easily increased. The upper limit of the tensile strength of the fiber contained in the bundle yarn of the present invention is not particularly limited, but is, for example, 30 cN / dtex or less. The tensile strength of the fiber is measured in accordance with JIS L1013:2021 "Test Methods for Chemical Fiber Filaments (8.5)".

[0092] <Hydraulic Composition and Molded Article> A hydraulic composition can be obtained by mixing the convergence yarn of the present invention with a cement component, aggregate, and water. By hardening the hydraulic composition, a molded article such as mortar concrete can be produced. The hydraulic composition is less likely to generate fiber balls, and molded articles produced using the convergence yarn of the present invention have high toughness, making them useful as various building materials such as wall materials and roofing materials. The present invention also provides a hydraulic composition containing at least the convergence yarn of the present invention, a cement component, aggregate, and water, as well as a molded article obtained by hardening the hydraulic composition. The convergence yarn of the present invention is preferably contained in the hydraulic composition and molded article of the present invention in a state in which the fibers are separated (defibrated), but may also be contained in a state in which the fibers remain united by a sizing agent (as a convergence yarn). Therefore, when a hydraulic composition and molded article contain the convergence yarn of the present invention, it means that the convergence yarn of the present invention is contained in at least a portion in a state in which the fibers are separated (defibrated), and may also be contained in a state in which multiple fibers remain united by a sizing agent.

[0093] The hydraulic material contained in the hydraulic composition may include a cement component. Examples of the cement component include Portland cement such as ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, and moderate-heat Portland cement, alumina cement, blast-furnace cement, silica cement, and fly ash cement. These cements may be used alone or in combination.

[0094] (Aggregate) As the aggregate contained in the hydraulic composition, various aggregates can be used as needed. Examples of such aggregates include fine aggregate, coarse aggregate, lightweight aggregate, and functional aggregate. These aggregates may be used alone or in combination of two or more.

[0095] The fine aggregate in the present invention is an aggregate containing 85% by mass or more of particles with a particle size of 5 mm or less. Examples of fine aggregate include powdered or granulated inorganic materials such as sand, silica stone, fly ash, blast furnace slag, volcanic ash-based shirasu, various sludges, and rock minerals. Examples of sand include river sand, mountain sand, sea sand, crushed sand, silica sand, slag, glass sand, iron sand, ash sand, calcium carbonate, and artificial sand. These fine aggregates may be used alone or in combination.

[0096] The coarse aggregate in the present invention is an aggregate containing 85% by mass or more of particles with a particle size of 5 mm or more. Examples of coarse aggregate include various types of gravel, artificial aggregate (such as blast furnace slag), and recycled aggregate (such as recycled aggregate from construction waste). These coarse aggregates may be used alone or in combination of two or more. In a preferred embodiment of the present invention, the amount of coarse aggregate contained in the hydraulic composition is preferably 0 to 5% by volume, more preferably 0 to 3% by volume, and even more preferably 0 to 1% by volume, based on the total amount of aggregate. Even more preferably, the aggregate does not contain coarse aggregate.

[0097] The term "lightweight aggregate" as used herein refers to aggregate having an absolute dry specific gravity of 2.0 or less. Examples of lightweight aggregate include natural lightweight aggregates such as volcanic gravel, expanded slag, and charcoal husk, as well as artificial lightweight aggregates such as expanded perlite, expanded black rock, vermiculite, shirasu balloons, and fly ash microballoons. These lightweight aggregates may be used alone or in combination.

[0098] In the present invention, functional aggregates include colored aggregates, hard aggregates, elastic aggregates, and aggregates having a specific shape, and specific examples include layered silicates (e.g., mica, talc, kaolin), alumina, silica, etc. The proportion of functional aggregates can be set appropriately depending on the type of each aggregate. For example, the mass ratio of aggregates other than functional aggregates to functional aggregates (aggregates other than functional aggregates / functional aggregates) may be 99 / 1 to 70 / 30, preferably 98 / 2 to 75 / 25, and more preferably 97 / 3 to 80 / 20. These functional aggregates may be used alone or in combination of two or more types.

[0099] The mass ratio of the total amount of aggregate (S) to the cement component (C) (aggregate (S) / cement component (C)) may be preferably 1 / 10 to 5 / 1, more preferably 1 / 8 to 4 / 1, and even more preferably 1 / 6 to 3 / 1. In the hydraulic composition, the ratio of the mass of water to the mass of cement component (water / cement component) is preferably 20 to 75 mass%, more preferably 30 to 75 mass%.

[0100] The hydraulic composition may contain various admixtures as needed. Examples of admixtures include air-entraining agents, superplasticizers, water-reducing agents, high-performance water-reducing agents, air-entraining water-reducing agents, high-performance air-entraining water-reducing agents, thickeners, water-retention agents, water-repellents, expansion agents, hardening accelerators, setting retarders, and polymer emulsions (acrylic emulsions, ethylene-vinyl acetate emulsions, and SBR (styrene butadiene rubber) emulsions). These admixtures may be used alone or in combination. Polymer emulsions not only improve the brittleness of the final molded body, but also strengthen the adhesive strength between components in the molded body. Furthermore, the incorporation of polymer emulsions can improve the water-resistance of the molded body and prevent excessive drying.

[0101] The hydraulic composition may contain a water-soluble polymeric substance as needed. Examples of the water-soluble polymeric substance include cellulose ethers such as methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose, polyvinyl alcohol, polyacrylic acid, and lignin sulfonate. These water-soluble polymeric substances may be used alone or in combination.

[0102] The amount of the bundle yarn of the present invention added to the hydraulic composition can be appropriately set depending on the type, fiber length, aspect ratio, etc. of the fiber contained in the bundle yarn of the present invention, but for example, the amount of fiber may be added in an amount such that the amount of fiber is preferably 0.1 to 7 volume %, more preferably 0.3 to 5 volume %, and even more preferably 0.5 to 4 volume %, based on the volume of the final molded body to be obtained. When the amount of the bundle yarn added is within the above range, the reinforcing effect of the fiber is enhanced, and entanglement of fibers due to an excessive fiber content is easily suppressed, making it easy to improve the reinforcing effect of the fiber.

[0103] The molded body can be obtained by hardening a hydraulic composition containing the converging yarn of the present invention, water, cement components, aggregate, and, if necessary, various admixtures and the like within a range that does not impair the effects of the present invention.

[0104] <Method for manufacturing hydraulic composition and molded product> The hydraulic composition is kneaded by a known or commonly used kneading means such as a mixer. The kneading order of the constituent materials is not particularly limited, but is appropriately adjusted depending on the constitution of the hydraulic composition, the water / cement ratio (W / C), etc., in order to minimize physical impact on the fibers.

[0105] The water / cement ratio (W / C) in the hydraulic composition is adjusted appropriately depending on the constitution of the hydraulic composition, etc., but is preferably 20 to 75 mass%, more preferably 30 to 75 mass%, and even more preferably 40 to 75 mass%.

[0106] The method of feeding the bundle yarn of the present invention to the hydraulic composition is not particularly limited. For example, various constant-volume feeding devices (e.g., vibration feeders, screw feeders, belt feeders, etc.) can be used as devices for feeding the fibers while controlling the input amount and / or input speed.

[0107] In the hydraulic composition of the present invention, the method for dispersing the fibers defibrated from the bundle yarn in the hydraulic composition is not particularly limited as long as the fibers can be dispersed in a state where they are substantially not present as fiber aggregates. For example, a continuous kneader such as a double-arm kneader, a pressure kneader, an Eirich mixer, a super mixer, a planetary mixer, a Banbury mixer, or a continuous mixer can be used.

[0108] After the hydraulic composition containing the dispersed fibers of the binder yarn of the present invention is poured into a formwork, vibration may be applied as necessary. Vibration may be applied using JIS A8610:2004 "Construction Machinery and Equipment - Internal Concrete Vibrators" or JIS A8611:2004 "Construction Machinery and Equipment - External Concrete Vibrators." Vibration makes it easier for the hydraulic composition to be densely packed into the formwork.

[0109] After molding into a predetermined shape, the hydraulic composition is generally cured in an atmosphere of 100° C. or less to harden, thereby obtaining a molded article.

[0110] The hydraulic composition containing the bundle yarn of the present invention can be used for any purpose, and can be used to produce molded articles for various purposes, such as blocks, floor panels, wall panels, partitions, roofing materials, and roof tiles.

[0111] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0112] [Measurement or Evaluation Method] <Evaluation of Mixture> (Average Particle Diameter) Oil and / or sizing agent were mixed with water to the concentrations described in the examples, and the mixture was stirred at 300 rpm with a magnetic stirrer (manufactured by Advantec Toyo Co., Ltd.) until uniform. Water was then added so that the concentration of the resulting mixture was 25 mg / L (as non-volatile components), and the mixture was stirred at 120 rpm for 5 minutes. The particle size of the resulting diluted solution was evaluated using a particle size analyzer (ELS-Z, manufactured by Otsuka Electronics Co., Ltd.). The solution temperature during preparation and measurement of the mixture was 25°C.

[0113] <Fiber evaluation> (Fineness) Measured in accordance with JIS L1015:2021 "Test method for synthetic fiber staples (8.5)". (Fiber density) Measured in accordance with JIS L1015:2021 "Test method for synthetic fiber staples (8.14)". (Tensile strength) Measured in accordance with JIS L1013:2021 "Test method for synthetic fiber filament yarns (8.5)" using uncut filament-like yarns with no sizing agent attached.

[0114] (Fiber diameter) The fineness (T (dtex)) and fiber density (ρ ｆ (g / cm ３ )) and calculated D (average fiber diameter) using the following formula. The average fiber diameter may be determined by randomly selecting 100 fibers, measuring the fiber diameter at the center of each fiber in the longitudinal direction using an optical microscope, and averaging the measured values.

[0115] (Aspect ratio) The aspect ratio refers to the ratio (L / D) of fiber length (L) to fiber diameter (D). In the present invention, the average fiber length was calculated by taking the length of the convergence yarn as the fiber length with reference to JIS L1015:2021 "Test methods for chemical fiber staples (8.4)," and the aspect ratio was calculated from the ratio to the fiber diameter.

[0116] <Evaluation of bundled yarn> (Oil content per unit surface area of ​​fiber) First, the oil content W per mass of fiber ＯThe oil content Y (mass %) (Y (mass %)) was measured by the following method. The bundle yarn whose bone dry mass had been measured was immersed in distilled water maintained at 80°C for 3 hours, and the water-soluble resin and oil were dissolved in the distilled water. The bundle yarn and the aqueous solution were then separated to obtain an aqueous solution in which the water-soluble resin and oil were dissolved. The obtained aqueous solution was evaporated to dryness to obtain a residue, and the oil content W per mass of fiber was calculated from the ratio of the mass of the oil attached to the bundle yarn to the total mass of the oil and water-soluble resin attached to the bundle yarn. Ｏ The oil content (mass%) per mass of fiber was calculated using the following formula: Ｏ ) = (mass of residue) ÷ (bone dry mass of bundle yarn) × (ratio of mass of oil agent attached to bundle yarn to total mass of oil agent and water-soluble resin attached to bundle yarn) Note that in the above, the oil agent was separated from the bundle yarn by dissolution and the content of oil agent per mass of fiber was calculated, but if it is considered that all of the oil agent added when manufacturing the bundle yarn is attached to the fiber, the content of oil agent per mass of fiber can also be determined from the amount of oil agent attached to the fiber.

[0117] Next, the circumferential length L (cm) of the cross section of the fiber was calculated using the following formula. L (cm): Circumference of the cross section of the fiber T (dtex): Fineness of the fiber ρ ｆ (g / cm ３ From these values, the oil content per unit surface area of ​​the fiber (mg / cm) is calculated using the following formula: ２ ) to 10 ４ Multiply it by "mg / m ２ " is displayed. [Wherein, T (dtex) represents the fineness of the fiber, W Ｏ (mass %): mass of oil per mass of fiber, L (cm): circumferential length of cross section of fiber] The content of oil per unit surface area of ​​fiber shown here refers to the content of organic components other than water-soluble resins and inorganic substances. The results are shown in Table 1.

[0118] (Water-soluble resin content per unit surface area of ​​fiber) Water-soluble resin content W per mass of fiber ｒThe water-soluble resin content X (mass%) was measured by the following method. The water-soluble resin content W (mass%) per fiber mass was calculated from the ratio of the mass of the water-soluble resin attached to the bundle yarn to the total mass of the oil and water-soluble resin attached to the bundle yarn. ｒ The content of water-soluble resin per mass of fiber (% by mass) was calculated using the following formula: ｒ ) = (mass of residue) ÷ (bone dry mass of bundle yarn) × (ratio of the mass of water-soluble resin attached to the bundle yarn to the total mass of oil and water-soluble resin attached to the bundle yarn) In the above, the water-soluble resin was separated from the bundle yarn by dissolution and the content of water-soluble resin per mass of fiber was calculated, but if it is considered that all of the water-soluble resin added when manufacturing the bundle yarn is attached to the fiber, the content of water-soluble resin per mass of fiber can also be determined from the amount of water-soluble resin attached to the fiber.

[0119] Next, in the above formula (1) for calculating the content of the oil per unit surface area of ​​the fiber, the mass of the oil per mass of the fiber is calculated as W ｏ (mass%), the mass W of the water-soluble resin per mass of the fiber ｒ (mass%) was calculated using the following formula. [Wherein, T (dtex) represents the fineness of the fiber, W ｒ (mass %): mass of water-soluble resin per mass of fiber L (cm): circumferential length of cross section of fiber] From these values, the content of water-soluble resin per unit surface area of ​​fiber (mg / cm) is calculated by the following formula: ２ ) to 10 ４ Multiply it by "mg / m ２ " is displayed.

[0120] (The ratio of the content of the oil agent based on the total amount of the bundle thread to the content of the water-soluble resin based on the total amount of the bundle thread) W calculated from the above ｏ Y, W ｒ The ratio (Y / X) of the content of the oil agent based on the total amount of the bundle thread to the content of the water-soluble resin based on the total amount of the bundle thread was calculated, where X was the value of the oil agent content based on the total amount of the bundle thread.

[0121] (Fiber Cohesion of Bundle Threads) No. 5 silica sand, sea sand, and ordinary Portland cement were mixed in a mass ratio of 50:24.5:25 into a Hobart mixer (manufactured by Marubishi Scientific Machinery Manufacturing Co., Ltd.) and mixed for 30 seconds at 120 rpm. Then, 0.5% by mass of bundle threads were added to the mixture and mixed for 90 seconds at 120 rpm in the same Hobart mixer. To the resulting mixture, 17.3% by mass of water was added and mixed for 60 seconds at 120 rpm in the same Hobart mixer to obtain a hydraulic composition. The resulting hydraulic composition was placed on a sieve with a nominal mesh size of 4.75 mm. The silica sand, sea sand, and cement were washed away with water, and the mass A (g) of the bundle threads remaining on the sieve, the mass B (g) of the fiber balls remaining on the sieve, and the mass C (g) of the defibrated fibers that fell through the sieve were measured. The fiber aggregation degree (B / (A+B+C)) was calculated from the obtained masses of A, B, and C. The obtained results are shown in Table 1.

[0122] (Degree of fiber defibration of bundle yarn) The degree of fiber defibration (C / (A+C)) was calculated from the masses of A and C obtained above. The obtained results are shown in Table 1.

[0123] The following materials were used in the examples and comparative examples. (Fibers) PVA Fiber 1: A fully saponified PVA (manufactured by Kuraray Co., Ltd.) with a viscosity-average degree of polymerization of 1,700 was dissolved in a solvent to prepare a spinning dope. The spinning dope was wet-spun in a coagulation bath, roller-stretched, solvent-extracted, and dried. Then, in the same fiber-manufacturing process, a drawn yarn (PVA Fiber 1) was obtained by stretching the yarn at 230-240°C and a draw ratio of 8-10 times at 230-240°C in a stretching heat treatment step. PVA Fiber 1 had a fiber diameter of 38 μm, a tensile strength of 12 cN / dtex, and a fineness of 15 dtex. PVA Fiber 2: PVA Fiber 2 was obtained in the same manner as PVA Fiber 1, except that the extrusion amount of the dope into the coagulation bath and the draw ratio (10-12 times) were changed. The PVA fiber 2 had a fiber diameter of 27 μm, a tensile strength of 13 cN / dtex, and a fineness of 7 dtex.

[0124] (Sizing agent: water-soluble resin) Acrylic acid-modified PVA1: A modified polyvinyl alcohol having a viscosity-average degree of polymerization of 1,500, a degree of saponification of 99.5 mol%, a solubility of 86% by mass in alkaline water of pH 12 at room temperature (20°C), a solubility of 47% by mass in water of pH 7 at room temperature (20°C), a content of 5 mol% of structural units (X) derived from acrylic acid, a content of 4.8 mol% of structural units (X1), a content of 0.2 mol% of structural units (X2), a ratio of (X1) to the total amount of structural units (X1) and (X2) of 0.96, and in which the functional groups X and Y in the structural units (X1) and (X2) are both hydrogen atoms. PVA2: A polyvinyl alcohol having a viscosity-average degree of polymerization of 1,700, a degree of saponification of 88.0 mol%, a solubility of 62% by mass in alkaline water of pH 12 at room temperature (20°C), and a solubility of 65% by mass in water of pH 7 at room temperature (20°C). PVA3: Polyvinyl alcohol having a viscosity average degree of polymerization of 1,700, a degree of saponification of 96.0 mol%, a solubility of 49% by mass in alkaline water of pH 12 at room temperature (20°C), and a solubility of 43% by mass in water of pH 7 at room temperature (20°C).

[0125] (Oil Agents) - Oil Agent A Oil Agent A is an oil agent containing 15 mass% or more of a nonionic surfactant and 75 mass% or more of an oxidized polyolefin, a low-polarity oil, relative to the total amount of the oil agent. The average particle diameter of a mixture of oil Agent A and water obtained by mixing oil Agent A and water so that the concentration of non-volatile components was 25 mg / L was measured by the above-mentioned method, and the average particle diameter was 97 nm. Water is not included as a component of oil Agent A.

[0126] Oil Agent B Oil Agent B is an oil agent containing 30% by mass or less of a nonionic surfactant relative to the total amount of the oil agent. When the average particle diameter of a mixture of oil Agent B and water obtained by mixing oil Agent B and water so that the concentration of nonvolatile components was 25 mg / L was measured by the above-mentioned method, the average particle diameter was 36 nm. Water is not included in the components of oil Agent B.

[0127] (Cement) Ordinary Portland cement (manufactured by Taiheiyo Cement Corporation) (Aggregate) Toyo Silica Sand No. 5 (manufactured by Toyo Materan Co., Ltd.) (Fly ash) Shiden fly ash (type II) (manufactured by Shiden Business Co., Ltd.) (Admixture) Chupol SSP-104 (manufactured by Takemoto Oil & Fat Co., Ltd.) Hi Metrose 90SH4000 (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0128] (Example 1) A mixed liquid containing 20 g / L of acrylic acid-modified PVA1 and 40 g / L (as non-volatile components) of oil agent A was applied to PVA fiber 1 by roller touch in an amount of 10.0 mass % relative to the mass of PVA fiber 1, and then cut to a length of 8 mm to obtain convergence yarn 1 with an aspect ratio of 211.

[0129] Example 2 A bundle yarn 2 was obtained in the same manner as in Example 1, except that the amount of oil agent A in the mixed solution in Example 1 was changed to 60 g / L (as a non-volatile component).

[0130] Example 3 A bundle yarn 2 was obtained in the same manner as in Example 1, except that the amount of oil agent A in the mixed solution in Example 1 was changed to 80 g / L (as a non-volatile component).

[0131] (Example 4) For the mixed solution of Example 1, the amount of acrylic acid-modified PVA 1 was 45 g / L, the amount of oil agent A was 85 g / L (as non-volatile components), and they were attached at 20.0 mass % relative to the mass of PVA fiber 1, but the same procedure as in Example 1 was repeated to obtain a convergence yarn 4.

[0132] Example 5 A bundle yarn 5 was obtained in the same manner as in Example 1, except that oil agent B was used instead of oil agent A in Example 1.

[0133] Example 6 A bundle yarn 6 was obtained in the same manner as in Example 1, except that the acrylic acid-modified PVA1 in Example 1 was replaced with PVA2.

[0134] (Example 7) A bundle yarn 7 was obtained in the same manner as in Example 1, except that the amount of acrylic acid-modified PVA 1 in the mixed solution in Example 1 was 10 g / L and the amount of oil agent A was 20 g / L (as a non-volatile component).

[0135] Example 8 A bundle yarn 8 was obtained in the same manner as in Example 1, except that the acrylic acid-modified PVA 1 in the mixed solution in Example 1 was 5 g / L and the oil agent A was 10 g / L (as non-volatile components).

[0136] (Example 9) A mixed liquid containing 30 g / L of acrylic acid-modified PVA1 and 60 g / L (as non-volatile components) of oil agent A was applied to PVA fiber 2 by roller touch in an amount of 10.0 mass % relative to the mass of PVA fiber 2, and then cut to a length of 6 mm to obtain a convergent yarn 9 with an aspect ratio of 226.

[0137] A bundle yarn 10 was obtained in the same manner as in Example 1, except that the acrylic acid-modified PVA1 in the mixed solution of Example 1 was changed to PVA3.

[0138] Example 11 A bundle yarn 11 was obtained in the same manner as in Example 1, except that the acrylic acid-modified PVA 1 in the mixed solution in Example 1 was changed to 44 g / L (as a non-volatile component).

[0139] Comparative Example 1 A bundle yarn 12 was obtained in the same manner as in Example 1, except that the mixed solution of Example 1 did not contain acrylic acid-modified PVA 1 and the amount of oil agent A was 70 g / L (as a non-volatile component).

[0140] (Comparative Example 2) The mixture solution of Example 1 was prepared in the same manner as Example 1, except that it did not contain oil agent A, the amount of acrylic acid-modified PVA 1 was 40 g / L (as a non-volatile component), and it was attached at 15.0 mass % relative to the mass of the PVA fiber 1.

[0141] (Comparative Example 3) A bundle yarn 14 was obtained in the same manner as in Example 1, except that the amount of acrylic acid-modified PVA 1 in the mixed solution in Example 1 was 2 g / L and the amount of oil agent A was 4 g / L (as non-volatile components).

[0142] <Evaluation of Toughness of Molded Products> (Preparation of Measurement Samples: (1) Kneading Step) Hydraulic compositions were prepared for each of the resulting bundle threads 1 to 14 according to the following method. Shiden fly ash (Type II), silica sand No. 5, and ordinary Portland cement were added to a Hobart mixer (Marubishi Scientific Machinery Works, Ltd.) in amounts such that the volume ratio of Shiden fly ash to silica sand No. 5 and ordinary Portland cement was 13.5:20.1:19.5, and mixed for 30 seconds in a dry state at 120 revolutions per minute. Subsequently, the bundle thread was added to the hydraulic composition at 2% by volume, and the mixture was mixed for 120 seconds. Furthermore, water was added so that the water / ordinary Portland cement ratio was 66% by mass, and the mixture was kneaded for 120 seconds to obtain hydraulic compositions 1 to 14.

[0143] (Preparation of Measurement Samples: (2) Molding Step) Using the obtained hydraulic compositions 1 to 14, six molded bodies were prepared for each of the hydraulic compositions 1 to 14 according to the following method, and these were used as measurement samples. First, the hydraulic composition obtained by the kneading step was evenly filled into a formwork having a width of 4 cm and a length of 18 cm using a vibrator, aiming for a thickness of 1 cm. Next, for initial curing, the hydraulic composition was held in an environment of a temperature of 20°C and a humidity of 60% for 24 hours. Further, for heat curing, the hydraulic composition was cured in an environment of a temperature of 50°C and a humidity of 95% for 24 hours. Thereafter, the molded bodies were removed from the formwork and left to stand for 96 hours under conditions of a temperature of 20°C and a humidity of 60%, to obtain molded bodies 1 to 14, which were used as measurement samples.

[0144] (Toughness) A three-point bending test was carried out using a precision universal testing machine (Shimadzu Corporation, Autograph AGX-50kNV) under the conditions of a test speed (crosshead speed) of 2 mm / min, a centralized loading method, and a bending span of 100 mm, and a stress-strain curve was obtained from the obtained load-displacement relationship. The integral value of the stress-strain curve from the position where the strain was 0 to the position where the strain was 0.03 on the obtained stress-strain curve was defined as toughness (N / mm ２ From the toughness values ​​obtained for the six measurement samples, the average value of the toughness and the coefficient of variation (=standard deviation / average value) were calculated.

[0145]

[0146] It was confirmed that the bundle yarns of the present invention in Examples 1 to 11 were bundle yarns that had high toughness and provided molded articles with small toughness variations. In contrast, the bundle yarns of the comparative examples were not able to provide sufficient toughness, or, even if they had high toughness, did not provide molded articles with small toughness variations.

Claims

1. A sizing yarn comprising a plurality of fibers held together by a sizing agent, the sizing agent being a water-soluble resin, the sizing yarn further comprising a sizing agent having a water-soluble resin content of 5 mg / m per unit surface area of ​​the fibers. ２ A converging thread containing an oil agent in an amount equal to or greater than the above content.

2. 30 mg / m per unit surface area of ​​fiber ２ The bundle yarn according to claim 1 , containing an oil agent in an amount of 100% or more.

3. 500 mg / m per unit surface area of ​​fiber ２ The bundle yarn according to claim 1 , comprising an oil agent in the following content:

4. The bundle yarn according to claim 1, wherein the bundle agent and the oil are in a mixed state.

5. The bundle yarn according to claim 1, wherein the average fiber diameter of the fibers is 3 to 900 μm.

6. The converging yarn according to claim 1, wherein the oil agent comprises an oil and / or a surfactant.

7. The convergence yarn according to claim 1, wherein the water-soluble resin dissolves by 60% or more when 2 parts by weight of the water-soluble resin is added to 100 parts by weight of alkaline water having a pH of 12 and stirred at 20°C for 5 minutes.

8. The convergence yarn according to claim 1, wherein the water-soluble resin contains a constituent unit derived from vinyl alcohol.

9. The water-soluble resin is 4 mg / m per unit surface area of ​​the fiber. ２ The bundle yarn according to claim 1, wherein the bundle yarn contains the above content.

10. The water-soluble resin is 200 mg / m per unit surface area of ​​the fiber. ２ The bundle yarn according to claim 9, wherein the bundle yarn contains the following:

11. The bundle yarn according to claim 1, wherein the ratio (Y / X) of the content of the oil (Y mass%) based on the total amount of the bundle yarn to the content (X mass%) of the water-soluble resin based on the total amount of the bundle yarn is 1 to 15.

12. The convergent yarn of claim 1, wherein the aspect ratio of the fibers is from 30 to 2,500.

13. A method for producing a bundle yarn containing a plurality of fibers, comprising the following step 1: (Step 1) attaching an oil-in-water dispersion containing a sizing agent, which is a water-soluble resin, an oil agent, and water to the surface of the fibers.

14. The method according to claim 13, wherein the average particle size of the dispersed particles contained in the oil-in-water dispersion is 1 to 500 nm.

15. A bundle yarn produced by the method according to claim 13 or 14.

16. An aqueous sizing composition comprising a binder which is a water-soluble resin, an oil agent, and water, wherein the water content is 80 mass% or more based on the total amount of the aqueous sizing composition, the aqueous sizing composition is an oil-in-water dispersion, and the average particle size of the dispersed particles is 1 to 500 nm.

17. A hydraulic composition comprising at least the bundle thread according to any one of claims 1 to 12, a cement component, aggregate and water.

18. The hydraulic composition according to claim 17, wherein the aggregate does not include coarse aggregate.

19. The hydraulic composition according to claim 17, wherein the ratio of the mass of water to the mass of the cement component (water / cement component) is 20 to 75 mass %.

20. A molded body obtained by hardening the hydraulic composition according to claim 17.

21. The convergence yarn according to claim 1, produced using an oil in an oil-in-water dispersion having a solids concentration of 25 mg / L, the average particle size of which is 0.1 to 800 nm.

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