Surface-modified fibers, method for producing same, and molded article using surface-modified fibers

Abstract

Provided are surface-modified fibers comprising fibers and a surface-modified layer covering at least a portion of the surface of the fibers, the surface-modified fibers being characterized in that the surface-modified layer contains a compound having hydrogen-bonding functional groups and that the amount of this surface-modified layer is 0.01 to 2.5 parts by mass per 100 parts by mass of fibers used as a starting material.

Description

Surface-modified fiber, its manufacturing method, and molded body using surface-modified fiber

[0001] The present invention relates to a surface-modified fiber having excellent adhesion to resin and concrete, a method for producing the same, and a molded article using the surface-modified fiber.

[0002] Synthetic fibers such as polyvinyl alcohol and polyamide are strong and durable, lightweight, and inexpensive, and therefore are used as fibers to reinforce concrete and the like to improve the strength of buildings and prevent cracking. These synthetic fibers are also used to reinforce automobile tires, oil brake hoses, and the like. When using these fibers for this purpose, they must be firmly bonded to rubber, so surface-modified fibers with modified surfaces are used.

[0003] As a specific example of the surface-modified fiber, Patent Document 1 discloses a fiber coated with branched polyethyleneimine in a proportion of about 0.2 to about 20% by mass based on the total weight of the coated fiber. Patent Document 2 also describes a reinforcing fiber having a surface-modified layer covering at least a portion of the surface of the fiber, wherein the surface-modified layer contains a specific polyamine compound.

[0004] JP 2022-511602 A International Publication No. 2022 / 044460

[0005] Although the surface-modified fibers described above exhibit a certain degree of performance in terms of adhesiveness, etc., there is room for improvement. Specifically, the fiber described in Patent Document 1 does not have sufficient adhesive strength and improvement is desired, and the fiber described in Patent Document 2 has the problem of coloring due to treatment at a relatively high temperature. In addition, chemical fibers generally have extremely low adhesiveness and adhesion to resins, so the development of a method for improving these properties has been desired.

[0006] The present invention has been made in consideration of the above-mentioned conventional problems, and provides a surface-modified fiber that has excellent adhesion to resins and concrete and can suppress coloration, a method for producing the same, and a molded article using the surface-modified fiber.

[0007] As a result of intensive research to solve the above-mentioned problems, the inventors discovered that by providing a surface modification layer containing a compound having a hydrogen-bonding functional group on at least a portion of the surface of the fiber, the adhesion between the fiber and resin, and between the fiber and concrete, can be improved, and thus completed the present invention.

[0008] That is, the present invention relates to the following [1] to [6]. [1] A surface-modified fiber having a fiber and a surface-modified layer covering at least a portion of the surface of the fiber, wherein the surface-modified layer contains a compound having a hydrogen-bonding functional group, and the amount of the surface-modified layer is 0.01 to 2.5 parts by mass per 100 parts by mass of the raw fiber. [2] The surface-modified fiber according to [1], wherein the hydrogen-bonding functional group is one or more selected from the group consisting of a hydroxy group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a carbonyl group, an aldehyde group, an acetalized product of an aldehyde group, an amino group, and an amide group. [3] The surface-modified fiber according to [1] or [2], wherein the fiber is one or more types of fiber selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers. [4] The surface-modified fiber according to any one of [1] to [3] above, wherein the hue parameter (YI) of the surface-modified fiber is 0 to 50. [5] A method for producing the surface-modified fiber according to any one of [1] to [4] above, comprising the following steps (1) and (2): [Step (1)] preparing a solution or dispersion of the compound having the hydrogen-bonding functional group, and adhering the solution or dispersion to the fiber; [Step (2)] heat-treating the fiber to which the solution or dispersion has been adhered at 180 to 280°C for 50 seconds or less; [6] A molded article using the surface-modified fiber according to any one of [1] to [4] above.

[0009] The present invention can provide a surface-modified fiber that has excellent adhesion to resin and concrete and can suppress coloration, a method for producing the same, and a molded article using the surface-modified fiber.

[0010] [Surface-Modified Fiber] The surface-modified fiber of the present invention comprises a fiber and a surface-modified layer covering at least a portion of the fiber surface. The surface-modified layer contains a compound having a hydrogen-bonding functional group, and the amount of the surface-modified layer is 0.01 to 2.5 parts by mass per 100 parts by mass of the raw fiber. In the present invention, a surface-modified layer containing a compound having a hydrogen-bonding functional group is provided on at least a portion of the fiber surface. This results in strong affinity between the hydrogen-bonding functional group and the fiber, and between the hydrogen-bonding functional group and concrete or resin, resulting in improved adhesion between the fiber and resin, and between the fiber and concrete. Furthermore, the surface-modified layer is less susceptible to decomposition, making it possible to obtain a surface-modified fiber with excellent transparency. Note that, in the present invention, the "surface-modified layer covering at least a portion of the fiber surface" may refer to an embodiment in which the surface-modified layer is present on at least a portion of the fiber surface, for example, as a film or layer. Alternatively, the raw fiber material may contain components corresponding to the surface-modified layer, and the components of the surface-modified layer may be present on a portion of the surface of the fiber itself.

[0011] <Surface Modified Layer> The surface modified layer in the present invention is a layer containing a compound having a hydrogen-bonding functional group. In the present invention, by using a compound having a hydrogen-bonding functional group in the surface modified layer, it is possible to improve the adhesive strength between the surface modified fiber and resin, or between the surface modified fiber and concrete. In this specification, the term "hydrogen bond" refers to a bonding interaction formed between a hydrogen atom (donor) that is bonded to an atom with high electronegativity (O, N, S, etc.) and is electrically positively polarized, and an electronegative atom (acceptor) that has a lone electron pair.

[0012] Examples of the hydrogen-bonding functional group include a hydroxy group, an epoxy group, an ether group, a mercapto group, a carboxy group, a carbonyl group, an aldehyde group, an amino group, an imino group, an imidazole group, a urethane group, an amide group, a urea group, an isocyanate group, a nitrile group, a silanol group, and derivatives thereof. Examples of the carboxy group include a group derived from a monocarboxylic acid and a group derived from a dicarboxylic acid. Examples of derivatives of the carboxy group include a salt thereof, an esterified product thereof, an amidated product thereof, and an acid anhydride thereof. Examples of derivatives of the aldehyde group include an acetalized product thereof. Examples of derivatives of the silanol group include an esterified product thereof. Among these, one or more selected from a hydroxy group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a carbonyl group, an aldehyde group, an acetalized product of an aldehyde group, an amino group, and an amide group are preferred, and one or more selected from a carboxy group, a carbonyl group, an amino group, and an amide group are more preferred.

[0013] Specific compounds having the hydrogen-bonding functional group include compounds having a hydroxy group such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol; compounds having an amino group such as polyethyleneimine, polyallylamine, polyvinylamine, polydiallylmethylamine, polydiallylethylamine, and salts thereof; compounds having an amide group such as polyvinylpyrrolidone, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and ε-caprolactam; compounds having a carboxy group such as maleic acid, fumaric acid, citraconic acid, perpropionic acid, and itaconic acid; and the like. Among the compounds having the hydrogen-bonding functional group, polyethyleneimine, polyallylamine, and polyvinylpyrrolidone are preferred. The use of these compounds having hydrogen-bonding functional groups particularly improves the adhesion and transparency of the surface-modified layer.

[0014] The amount of the compound having a hydrogen-bonding functional group in the surface-modified layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably substantially 100% by mass. When the amount of the compound having a hydrogen-bonding functional group in the surface-modified layer is within the above range, it is possible to improve the adhesion between the fiber and the resin, and it is also possible to obtain a surface-modified fiber with excellent transparency.

[0015] The surface modification layer preferably covers the entire surface of the fiber from the viewpoint of improving adhesion to the resin, but it is sufficient that it substantially covers at least a portion of the surface of the fiber. The specific amount of the surface modification layer covering the surface of the fiber is 0.01 to 2.5 parts by mass, preferably 0.05 to 2.0 parts by mass, more preferably 0.1 to 1.5 parts by mass, even more preferably 0.15 to 1.2 parts by mass, even more preferably 0.15 to 1.0 parts by mass, and particularly preferably 0.2 to 0.5 parts by mass, relative to 100 parts by mass of the fibers used as raw material.

[0016] The surface modification layer may contain other components other than those described above, or may not contain other components. Examples of other components include crosslinkers, acids, bases, inorganic salts, organic salts, pigments, dyes, antioxidants, polymerization initiators, and plasticizers. When the surface modification layer contains the other components, the content of the other components in the surface modification layer is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of improving the adhesive strength with the resin.

[0017] In the present invention, the hue parameter (YI) of the surface-modified layer is preferably 0 to 50. When the hue parameter (YI) of the surface-modified layer is within the above range, it is possible to obtain a surface-modified fiber with excellent transparency. From this viewpoint, the hue parameter (YI) of the surface-modified layer is more preferably 0 to 45, even more preferably 0 to 35, even more preferably 0 to 30, and particularly preferably 0 to 25. The hue parameter (YI) of the surface-modified layer in the present invention is a hue measured in accordance with JIS Z8722:2009, and specifically can be measured by the method described in the examples.

[0018] <Fibers> There are no particular limitations on the fibers used in the surface-modified fibers of the present invention, and hydrophilic or hydrophobic fibers can be used. In the present invention, the term "fibers" includes not only short fibers and long fibers, but also nonwoven fabrics, woven fabrics, knitted fabrics, felts, sponges, and other forms.

[0019] Examples of hydrophilic synthetic fibers include synthetic fibers made of thermoplastic resins having hydrophilic functional groups such as hydroxyl groups, carboxyl groups, sulfonic acid groups, and amino groups, and / or hydrophilic bonds such as amide bonds. Specific examples of such thermoplastic resins include polyvinyl alcohol resins, polyamide resins (aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, and polyamide 9C (a polyamide composed of nonanediamine and cyclohexanedicarboxylic acid); semi-aromatic polyamides synthesized from aromatic dicarboxylic acids and aliphatic diamines, such as polyamide 9T (a polyamide composed of nonanediamine and terephthalic acid); fully aromatic polyamides synthesized from aromatic dicarboxylic acids and aromatic diamines, such as polyparaphenylene terephthalamide), and polyacrylamide resins. Among these, polyvinyl alcohol resins and polyamide resins are preferred. The hydrophilic synthetic fibers may be used alone or in combination of two or more types. Furthermore, these hydrophilic synthetic fibers may or may not be subjected to a hydrophilization treatment, which will be described later, in order to further enhance the hydrophilicity.

[0020] Examples of hydrophilic natural fibers include natural cellulose fibers such as wood pulp (e.g., kraft pulp) and non-wood pulp (e.g., cotton pulp and straw pulp). Examples of hydrophilic regenerated fibers include regenerated cellulose fibers such as rayon, lyocell, cupra, and polynosic. These natural fibers and regenerated fibers may be used alone or in combination of two or more. Furthermore, these hydrophilic natural fibers and regenerated fibers may or may not be subjected to a hydrophilization treatment described below to further enhance their hydrophilicity.

[0021] The hydrophilic fiber may have at least a hydrophilic surface, and may be, for example, a hydrophobic fiber whose surface has been hydrophilized, a core-sheath type composite fiber in which a hydrophobic resin is used as the core and a hydrophilic resin is used as the sheath, or a single-structure non-composite fiber without a core-sheath structure. Examples of hydrophilic resins that constitute the sheath are described in relation to hydrophilic synthetic fibers. Examples of hydrophobic fibers made of hydrophobic resins include the hydrophobic fibers described below.

[0022] The hydrophilization treatment is not particularly limited as long as it is a treatment that chemically or physically imparts hydrophilic functional groups to the fiber surface. For example, the hydrophilization treatment can be carried out by a method in which a hydrophobic fiber made of a hydrophobic resin described below is modified with a compound containing a hydrophilic functional group such as an isocyanate group, an epoxy group, a hydroxy group, an amino group, an ether group, an aldehyde group, a carbonyl group, a carboxy group, or a urethane group, or a derivative thereof, or by a method in which the surface is modified by electron beam irradiation.

[0023] The present invention can also use hydrophobic fibers that could not be firmly bonded to resins using conventional techniques. Hydrophobic fibers generally do not have polar functional groups on their surface, so they have poor affinity with adhesive components (described below) and cannot be firmly bonded to resins. However, by providing a surface-modified layer on the fiber surface as in the present invention, even hydrophobic fibers can be firmly bonded to resins.

[0024] Examples of hydrophobic fibers that can be used in the present invention include polyolefin fibers such as polyethylene and polypropylene, polyester fibers such as polyethylene terephthalate, and wholly aromatic polyester fibers. Among these, polyester fibers are preferred because of their excellent production costs, strength, heat resistance, durability, and the like.

[0025] In the present invention, among the above fibers, synthetic fibers and regenerated fibers are preferred, and one or more fibers selected from polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers are particularly preferred. In the present invention, one type of fiber may be used alone, or two or more types may be used in combination. The fibers used in the surface-modified fibers of the present invention preferably have a single filament fineness of 500 to 4,500 dtex. A single filament fineness of 500 dtex or more facilitates industrial production. Furthermore, a single filament fineness of 4,500 dtex or less facilitates maintaining the strength of the surface-modified fibers when used as reinforcing materials. From the above viewpoints, the single filament fineness of the fibers used in the surface-modified fibers of the present invention is more preferably 500 to 4,000 tex, and even more preferably 1,000 to 3,000 tex.

[0026] [Method for producing surface-modified fiber] The surface-modified fiber of the present invention is preferably produced by a production method comprising the following steps (1) and (2). When produced by a method comprising the following steps, it is possible to produce a surface-modified fiber while preventing decomposition of the surface-modified layer, and therefore it is possible to have excellent adhesive strength and suppress coloration. [Step (1)] A step of preparing a solution or dispersion of the compound having the hydrogen-bonding functional group and applying the solution or dispersion to the fiber. [Step (2)] A step of heat-treating the fiber to which the solution or dispersion has been applied at 180 to 280°C for 50 seconds or less.

[0027] In step (1), the solvent or dispersion medium for dissolving or dispersing the compound having a hydrogen-bonding functional group is not particularly limited, but from the viewpoints of storage stability and cost, water or a water-soluble organic solvent is preferred. Examples of water-soluble organic solvents include monohydric alcohols having 1 to 8 carbon atoms, such as methanol, ethanol, isopropanol, n-butanol, isopentyl alcohol, and tertiary butanol; polyhydric alcohols, such as ethylene glycol, diethylene glycol, and glycerin; ketones having 3 to 10 carbon atoms, such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone; and carbonate-based organic solvents, such as propylene carbonate. Among these, water and alcohols having 1 to 6 carbon atoms are more preferred, and water is even more preferred.

[0028] When the compound having a hydrogen-bonding functional group is dissolved or dispersed in the solvent or dispersion medium, the amount of the compound having a hydrogen-bonding functional group is preferably 0.01 to 30 parts by mass, more preferably 0.05 to 20 parts by mass, even more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the solvent or dispersion medium. When the amount of the compound having a hydrogen-bonding functional group per 100 parts by mass of the solvent or dispersion medium is within the above range, it becomes possible to uniformly attach the compound having a hydrogen-bonding functional group to the fiber while reducing production costs.

[0029] In the step (1), the method for applying the solution or dispersion of the compound having a hydrogen-bonding functional group to the fiber is not particularly limited, and it is preferable to apply the solution or dispersion by at least one method selected from, for example, immersion, a roll coater, an oiling roller, an oiling guide, nozzle (spray) application, brush application, and the like.

[0030] The temperature of the heat treatment in step (2) is preferably 180 to 280°C, more preferably 190 to 270°C, even more preferably 200 to 260°C, even more preferably 220 to 250°C, and even more preferably 230 to 250°C. If the heat treatment temperature exceeds the upper limit, discoloration occurs due to thermal decomposition. On the other hand, if the heat treatment temperature is below the lower limit, sufficient adhesiveness is not achieved.

[0031] The heat treatment time is preferably 0.1 to 50 seconds, more preferably 1 to 45 seconds, even more preferably 2 to 40 seconds, even more preferably 3 to 35 seconds, even more preferably 3 to 20 seconds, and even more preferably 3 to 10 seconds. If the heat treatment time exceeds the upper limit, discoloration occurs due to thermal decomposition. On the other hand, if the time is less than the lower limit, adhesiveness may decrease. Note that if the heat treatment time is 30 seconds or less, it is also possible to perform the treatment online using a heat treatment furnace in the polyvinyl alcohol fiber manufacturing process.

[0032] In the production of surface-modified fibers, the heat treatment may be carried out once, or twice or more times at different temperatures and times. However, multiple heat treatments at high temperatures may cause the surface-modified layer to decompose, which may result in discoloration or a decrease in adhesive strength.

[0033] <Physical Properties of Surface-Modified Fiber> In the present invention, surface-modified fibers of various shapes can be used depending on the application. For example, they may be short fibers such as cut fibers, or long fibers. In the case of long fibers, it is also a preferred embodiment that they are multifilaments.

[0034] The strength of the surface-modified fiber is preferably 4 to 30 cN / dtex, more preferably 5 cN / dtex or more. The strength of the surface-modified fiber in the present invention can be measured by the method described in the examples.

[0035] The surface-modified fiber of the present invention can be used in any shape, but is preferably used in the form of a fiber cord, woven fabric, knitted fabric, etc., which contains the surface-modified fiber at least in part, and more preferably used as a woven fabric or knitted fabric containing the surface-modified fiber at least in part. For example, as described below, it can also be used as a surface-modified fiber to be embedded in resin, cement, etc.

[0036] [Molded body] The molded body of the present invention is not particularly limited as long as it uses the surface-modified fiber. Since the surface-modified fiber has excellent adhesion to resin, it is preferable to use a molded body having the surface-modified fiber and a resin layer. From the viewpoint of maintaining the shape of the resin, the surface-modified fiber used in the molded body is preferably used as a woven or knitted fabric containing the surface-modified fiber at least in part, and more preferably used as part of a laminate in which a reinforcing layer made of the woven or knitted fabric and a resin layer are laminated.

[0037] The resin used in the molded article of the present invention is not particularly limited, and examples thereof include polyolefin resins such as polyethylene resin, polypropylene resin, and polybutylene resin; methacrylic resins such as polymethyl methacrylate resin; polystyrene resins such as polystyrene resin, ABS resin, and AS resin; polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate resin, polyethylene naphthalate (PEN) resin, and poly 1,4-cyclohexyldimethylene terephthalate (PCT) resin; polyamide (PA) resins such as 6-nylon resin, 6,6-nylon resin, and PA9T; polyvinyl chloride resin, polyoxymethylene (POM) resin, polycarbonate (PC) resin, and polyphenylene sulfide resin. Examples of suitable resins include polyphenylene ether (PPS) resins, modified polyphenylene ether (PPE) resins, polyetherimide (PEI) resins, polysulfone (PSF) resins, polyethersulfone (PES) resins, polyketone resins, polyarylate (PAR) resins, polyethernitrile (PEN) resins, polyetherketone (PEK) resins, polyetheretherketone (PEEK) resins, polyetherketoneketone (PEKK) resins, polyimide (PI) resins, polyamideimide (PAI) resins, and fluorine (F) resins; liquid crystal polymer resins such as liquid crystal polyester resins; thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, and fluorine-based elastomers; and copolymer resins and modified resins thereof. These resins may be used alone or in combination of two or more. Among these, polyvinyl chloride resins are preferred from the viewpoint of improving adhesion to surface-modified fibers.

[0038] The molded article of the present invention may be a fiber-reinforced resin obtained by mixing the surface-modified fiber with a resin. The resins described above can also be suitably used for the resin used in the fiber-reinforced resin. When the molded article of the present invention is a fiber-reinforced resin, the content of the surface-modified fiber per 100 parts by mass of the resin is preferably 0.1 to 50 parts by mass, more preferably 1 to 30 parts by mass. When the blending amount of the surface-modified fiber relative to the resin is within the above range, the dispersibility of the surface-modified fiber in the resin is improved, and an excellent reinforcing effect is exhibited.

[0039] The method for incorporating the surface-modified fiber of the present invention into the resin is not particularly limited, and for example, the surface-modified fiber is added to the resin pellets and mixed uniformly. The method for producing the fiber-reinforced resin is also not particularly limited, and molding methods such as melt extrusion molding and injection molding can be used.

[0040] The resin used in the molded article of the present invention may contain additives such as impact resistance improvers and inorganic fillers. Examples of additives include flame retardants, conductivity imparting agents, crystal nucleating agents, UV absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorizers, coloring inhibitors, heat stabilizers, release agents, antistatic agents, lubricants, colorants, and foaming agents. When the additives are used, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the resin. When the additive content is within the above range, the effects of the additives can be obtained while maintaining the reinforcing effect of the surface-modified fiber.

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. <Fibers> Polyvinyl alcohol fiber (PVA) Kuralon 5501 (2000 dtex, 1000 f) manufactured by Kuraray Co., Ltd. Polyamide fiber (PA) Nylon 6 melt-spun (1400 dtex, 204 f)

[0042] <Compounds Having Hydrogen-Bonding Functional Groups> [Polyethyleneimine (PEI)] Polyethyleneimine (1) "Epomin P-3000" manufactured by Nippon Shokubai Co., Ltd. Polyethyleneimine (2) "Epomin SP-200" manufactured by Nippon Shokubai Co., Ltd.

[0043] [Polyvinylpyrrolidone (PVP)] "Polyvinylpyrrolidone K-85" manufactured by Nippon Shokubai Co., Ltd. [Polyallylamine] "PAA-15" manufactured by Nittobo Medical Co., Ltd.

[0044] <Method for preparing a solution containing a compound having a hydrogen-bonding functional group> The solution used in Example 1 was prepared by mixing 14.3 g of polyethyleneimine (1) and 985.7 g of water. In other examples and comparative examples, aqueous solutions for forming surface-modified layers were prepared in the same manner using the compounds listed in Table 1.

[0045] Example 1: Polyvinyl alcohol-based fibers (PVA-based fibers) were immersed in an aqueous solution containing a compound having a hydrogen-bonding functional group, and then the solution was squeezed with a roller. The resulting fiber cord was dried at 140°C for 30 seconds. The cord was then heat-treated at 240°C for 5 seconds and wound up to produce a surface-modified fiber.

[0046] Examples 2 to 7, Comparative Examples 1 and 2 Surface-modified fibers were produced in the same manner as in Example 1, except that the production conditions and heat treatment conditions were changed to those shown in Table 1.

[0047] The fibers obtained in the examples and comparative examples were evaluated according to the following methods. The results are shown in Table 1. <Evaluation method> [Hue parameter (YI)] The hue parameter (YI) of the obtained surface-modified fibers was measured using a haze meter SH7000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS Z8722:2009. Values ​​were measured at three locations on the surface-modified fiber, and the arithmetic average value was used as the hue parameter (YI). The results are shown in Table 1.

[0048] [Strength] According to the test method of JIS L-1013:2010, the strength of the obtained surface-modified fiber was measured in air at 20 ° C. with a fiber length of 20 cm, an initial load of 0.25 g / d, and a pulling rate of 50% / min. The arithmetic average of the five measured values ​​was used as the value for this evaluation. The fiber thickness (dtex) was determined by the mass method.

[0049] [Interfacial shear stress] A resin for evaluation was prepared by adding 1% by mass of a curing agent to an unsaturated polyester resin (manufactured by Nippon Tokushu Toryo Co., Ltd.) and stirring the mixture. The resulting resin for evaluation was attached in the form of a ball so as to surround the surface-modified fiber obtained, and left to stand at room temperature (20°C) for 2 hours. Thereafter, the sample was heat-treated at 70°C for 2 hours. The fiber diameter and axial length (resin diameter) of the obtained sample were measured, and the sample was then fixed to a mount, and the adhesive strength was measured using a testing machine (INSTRON "Universal Material Testing Machine 3365"), and the interfacial shear stress was calculated using the following formula. Interfacial shear stress (N / mm ２ ) = Maximum detection load (N) / (π × fiber diameter (mm) × axial length (mm))

[0050] [Processability] In each example and comparative example, an aqueous solution containing a compound having a hydrogen-bonding functional group was applied to each fiber, and 5 kg of the surface-modified fiber was wound up. The degree of contamination (gum-up) of the holding roller through which the surface-modified fiber passed was evaluated according to the following evaluation criteria. Criteria G (good): No or little roller contamination due to gum-up, and no problems with spinning operability. B (bad): Significant roller contamination due to gum-up, single yarns taken up and winding during spinning, and problems with spinning operability.

[0051]

[0052] Examples 8 and 9 Surface-modified fibers were prepared in the same manner as in Example 1, except that compounds having hydrogen-bonding functional groups as listed in Table 2 were used. The resulting surface-modified fibers were then twisted at 120 turns / m to prepare a blind-like sample of 36 fibers / inch. A test piece was obtained by overlapping the sample with a soft polyvinyl chloride resin sheet and heating it at 1 MPa pressure and 160°C for 10 minutes. The resulting test piece was adjusted to a width of 1 inch, and the peel strength (N / inch) was measured using a measuring machine (INSTRON "Universal Material Tester 3365"). The results are shown in Table 2. The measurement results indicate that the larger the numerical value, the greater the adhesive strength between the surface-modified fiber and the polyvinyl chloride resin.

[0053] Comparative Example 3 A sample was prepared in the same manner as in Example 8, except that the surface modification treatment was not carried out, and the peel strength was measured. The results are shown in Table 2.

[0054]

[0055] As is clear from the results of the Examples and Comparative Examples, the present invention makes it possible to obtain surface-modified fibers that are excellent in adhesiveness and can suppress coloration.

Claims

1. A surface-modified fiber having a fiber and a surface-modified layer covering at least a part of the surface of the fiber, the surface modification layer contains a compound having a hydrogen-bonding functional group, and the amount of the surface modification layer is 0.01 to 2.5 parts by mass per 100 parts by mass of the fibers used as the raw material; The surface-modified fiber is characterized in that the fiber is one or more types of fiber selected from polyamide-based fibers, polyvinyl alcohol-based fibers, and regenerated cellulose-based fibers.

2. A surface-modified fiber having a fiber and a surface-modified layer covering at least a portion of a surface of the fiber, the surface modification layer contains a compound having a hydrogen-bonding functional group, and the amount of the surface modification layer is 0.01 to 2.5 parts by mass per 100 parts by mass of the fibers used as the raw material; the amount of the compound having a hydrogen-bonding functional group in the surface modification layer is 70% by mass or more, The surface-modified fiber is characterized in that the hydrogen-bonding functional group is one or more selected from a carboxy group, a salt of a carboxy group, an ester of a carboxy group, an acid anhydride of a carboxy group, a carbonyl group, an amino group, and an amide group.

3. The hydrogen-bonding functional group is at least one selected from a hydroxy group, a carboxy group, a salt of a carboxy group, an ester of a carboxy group, an acid anhydride of a carboxy group, a carbonyl group, an aldehyde group, an acetal of an aldehyde group, an amino group, and an amide group. The surface-modified fiber according to claim 1.

4. The surface-modified fiber according to claim 2, wherein the fiber is one or more types of fiber selected from polyamide-based fibers, polyvinyl alcohol-based fibers, polyester-based fibers, and regenerated cellulose-based fibers.

5. The surface-modified fiber according to any one of claims 1 to 4, wherein the hue parameter (YI) of the surface-modified fiber is 0 to 50.

6. The method for producing a surface-modified fiber according to any one of claims 1 to 4, comprising the following steps (1) and (2): [Step (1)] A step of preparing a solution or dispersion of the compound having a hydrogen-bonding functional group and applying the solution or dispersion to the fiber. [Step (2)] A step of heat treating the fiber to which the solution or dispersion is applied at 180 to 280° C. for 50 seconds or less.

7. A molded article using the surface-modified fiber according to any one of claims 1 to 4.

8. A surface-modified fiber having a fiber and a surface-modified layer covering at least a part of the surface of the fiber, the surface-modified layer containing a compound having a hydrogen-bonding functional group, and the amount of the surface-modified layer being 0.01 to 2.5 parts by mass per 100 parts by mass of the fiber used as a raw material; Resin or cement; A molded body using the above.

9. The molded body according to claim 8 , wherein the surface-modified fibers are embedded in the resin or cement.

10. The molded article according to claim 8 , comprising the surface-modified fiber and a resin layer.