Surface-modified fiber, reinforcing fiber, and molded article using the same

Abstract

To provide a surface-modified fiber which exhibits superior adhesion to resin and concrete and is capable of suppressing coloration, a method for producing the same, and a molded article using the surface-modified fiber.SOLUTION: Surface-modified fibers comprise: fibers; and a surface-modified layer that covers at least a portion of the surface of the fibers, wherein the surface-modified layer contains a compound having hydrogen-bonding functional groups, and the amount of the surface-modified layer is 0.01 to 2.5 pts.mass per 100 pts.mass of the fibers used as the starting material.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Synthetic fibers such as polyvinyl alcohol and polyamide are used as fibers for reinforcing concrete and the like for the purpose of improving the strength of buildings and preventing cracks because they are excellent in strength and durability, lightweight, and inexpensive. In addition, the synthetic fibers are also used as fibers for reinforcing automobile tires, oil brake hoses, and the like. When using the fibers for this application, since it is necessary to firmly adhere the fibers and rubber, surface-modified fibers with a modified surface are used.

[0003] As a specific example of the surface-modified fiber, Patent Document 1 discloses a fiber coated with branched polyethyleneimine at a ratio of about 0.2 to about 20% by mass based on the total weight of the coated fiber. In addition, Patent Document 2 describes a reinforcing fiber having a surface-modified layer or the like that covers at least a part of the surface of the fiber, wherein the surface-modified layer contains a specific polyamine compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although the fiber with the surface modified as described above exhibits certain performance in terms of adhesiveness and the like, there is still room for improvement. Specifically, the fiber described in Patent Document 1 has insufficient adhesive strength and improvement is desired. The fiber described in Patent Document 2 has a problem in that coloring occurs because it is processed at a relatively high temperature. In general, chemical fibers have extremely low adhesiveness and close adhesiveness with resins, so the development of methods for improving these has been desired.

[0006] The present invention has been made in view of the above-described conventional problems, and provides a surface-modified fiber having excellent adhesiveness with resins and concrete and capable of suppressing coloring, a method for producing the same, and a molded body using the surface-modified fiber.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors to solve the above problems, it has been found that by providing a surface-modified layer containing a compound having a hydrogen-bonding functional group on at least a part of the surface of the fiber, the adhesiveness between the fiber and the resin and between the fiber and the concrete is improved, and the present invention has been completed.

[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 part of the surface of the fiber, 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 with respect to 100 parts by mass of the fiber used as a raw material. A surface-modified fiber characterized by this. [2] The surface-modified fiber according to [1] above, wherein the hydrogen-bonding functional group is 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. [3] The surface-modified fiber according to [1] or [2] above, wherein the fiber is one or more fibers selected from polyamide-based fibers, polyvinyl alcohol-based fibers, polyester-based fibers, and regenerated cellulose-based fibers. [4] The parameter (YI) of the hue of the surface-modified fiber is 0 to 50, the [1] The surface-modified fiber according to any one of [1] to [3]. [5] A method for producing the surface-modified fiber according to any one of [1] to [4], having the following steps (1) and (2). [Step (1)] A step of preparing a solution or dispersion of the compound having the hydrogen-bonding functional group and attaching the solution or dispersion to the fiber [Step (2)] A step of heat-treating the fiber to which the solution or dispersion is attached 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]. [Effects of the Invention]

[0009] The present invention can provide a surface-modified fiber having excellent adhesiveness to resins and concrete and capable of suppressing coloring, a method for producing the same, and a molded article using the surface-modified fiber. [Embodiments for Carrying Out the Invention]

[0010] [Surface-modified fiber] The surface-modified fiber of the present invention is 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 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 with respect to 100 parts by mass of the fiber used as a raw material. In the present invention, since a surface-modified layer containing a compound having a hydrogen-bonding functional group is provided on at least a part of the fiber surface, a strong mutual affinity is exhibited between the hydrogen-bonding functional group and the fiber, and between the hydrogen-bonding functional group and concrete or resin. As a result, the adhesiveness between the fiber and the resin, and between the fiber and the concrete is improved. In addition, since the decomposition of the surface-modified layer hardly occurs, it becomes possible to obtain a surface-modified fiber having excellent transparency. In the present invention, the "surface modification layer that covers at least a part of the surface of the fiber" may be a mode in which the surface modification layer exists as a film or a layer on at least a part of the surface of the fiber, or a component corresponding to the surface modification layer may be included in the raw material of the fiber, and a mode in which the component of the surface modification layer exists on a part of the surface of the fiber itself may also be acceptable.

[0011] <Surface modification layer> The surface modification 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 modification layer, it becomes possible to improve the adhesive force between the surface-modified fiber and the resin, or between the surface-modified fiber and the concrete. In this specification, the "hydrogen bond" means a bonding interaction formed between a hydrogen atom (donor) that is bonded to an atom (O, N, S, etc.) with a high electronegativity and is electrically polarized positively, and an electrically negative atom (acceptor) having a lone pair of electrons.

[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 the derivative of the carboxy group include its salt, its esterified product, its amidated product, and its acid anhydride. Examples of the derivative of the aldehyde group include its acetalized product. Examples of the derivative of the silanol group include its esterified product. 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 preferable, and one or more selected from a carboxy group, a carbonyl group, an amino group, and an amide group are more preferable.

[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, polyvinylpyrrolidone, and the like are preferable. When these compounds having the hydrogen-bonding functional group are used, the adhesiveness and the transparency of the surface modification layer are particularly improved.

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

[0015] From the viewpoint of improving the adhesiveness with the resin, it is preferable that the surface modification layer covers the entire surface of the fiber, but substantially, it is sufficient to cover at least a part 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, still 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 with respect to 100 parts by mass of the fiber used as the raw material.

[0016] The surface modification layer may or may not contain other components other than those described above. Examples of other components include crosslinking agents, 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 still more preferably 5% by mass or less from the viewpoint of improving the adhesive strength with the resin.

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

[0018] <Fiber> There is no particular limitation on the fiber used for the surface-modified fiber of the present invention, and hydrophilic fibers or hydrophobic fibers can be used. In the present invention, the "fiber" includes not only short fibers and long fibers but also forms such as non-woven fabrics, woven fabrics, knitted fabrics, felts, and sponges.

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

[0020] Examples of hydrophilic natural fibers include natural cellulose fibers such as wood pulp such as kraft pulp, cotton pulp, and non-wood pulp such as 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. Further, these hydrophilic natural fibers and regenerated fibers may or may not be further subjected to a hydrophilization treatment described later to enhance the hydrophilicity.

[0021] The hydrophilic fiber only needs to have hydrophilicity at least on the surface. For example, it may be a fiber obtained by hydrophilizing the surface of a hydrophobic fiber, a core-sheath composite fiber having a hydrophobic resin as the core and a hydrophilic resin as the sheath, or the like, or it may be a non-composite fiber having a single structure without a core-sheath structure. For examples of the hydrophilic resin constituting the sheath portion, the description of hydrophilic synthetic fibers is cited. Examples of the hydrophobic fiber made of a hydrophobic resin include the hydrophobic fibers described later.

[0022] The hydrophilization treatment is not particularly limited as long as it is a treatment for imparting a hydrophilic functional group to the fiber surface chemically or physically. For example, a method of modifying a hydrophobic fiber made of a hydrophobic resin described later with a compound or its derivative 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 carboxyl group, and a urethane group, or a method of modifying the surface by electron beam irradiation can be used.

[0023] In the present invention, it is also possible to use hydrophobic fibers that could not be firmly adhered to the resin in the prior art. Since hydrophobic fibers generally do not have polar functional groups on the fiber surface, they have poor affinity with the adhesive components described later and could not be firmly adhered to the resin. However, by providing a surface modification layer on the fiber surface as in the present invention, even hydrophobic fibers can be firmly adhered to the resin.

[0024] Examples of the 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 manufacturing cost, strength, heat resistance, durability, etc.

[0025] In the present invention, among the above fibers, synthetic fibers and regenerated fibers are preferred, and among them, one or more fibers selected from polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers are preferred. In the present invention, one type of fiber may be used alone, or two or more types may be used in combination. The fiber used for the surface-modified fiber of the present invention preferably has a single-filament fineness of 500 to 4,500 dtex. When it is 500 dtex or more, it is easy to manufacture industrially. Further, when it is 4,500 dtex or less, it is easy to maintain the strength when the surface-modified fiber is used as a reinforcing material. From the above viewpoints, the fiber used for the surface-modified fiber of the present invention more preferably has a single-filament fineness of 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 having the following steps (1) and (2). By producing by a method having the following steps, it is possible to produce surface-modified fibers while preventing the decomposition of the surface-modified layer, so that it has excellent adhesive strength and can suppress coloring. [Step (1)] A step of preparing a solution or dispersion of the compound having a hydrogen-bonding functional group and attaching the solution or dispersion to the fiber [Step (2)] A step of heat-treating the fiber to which the solution or dispersion is attached at 180 to 280 ° C. for 50 seconds or less

[0027] In the step (1), there is no particular limitation on the solvent or dispersion medium for dissolving or dispersing the compound having a hydrogen-bonding functional group, but from the viewpoints of storage stability and cost, water or a water-soluble organic solvent is preferable. Examples of the water-soluble organic solvent 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, and ketones having 3 to 10 carbon atoms such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone, and organic solvents such as carbonate-based organic solvents such as propylene carbonate. Among these, water and alcohols having 1 to 6 carbon atoms are more preferable, and water is even more preferable.

[0028] When dissolving or dispersing the compound having the hydrogen-bonding functional group in the solvent or dispersion medium, the amount of the compound having the 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 still more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the solvent or dispersion medium. When the amount of the compound having the hydrogen-bonding functional group with respect to 100 parts by mass of the solvent or dispersion medium is within the above range, it becomes possible to uniformly attach the compound having the hydrogen-bonding functional group to the fiber while suppressing the production cost.

[0029] In the step (1), there is no particular limitation on the method of attaching the solution or dispersion of the compound having the hydrogen-bonding functional group to the fiber. For example, it is preferably carried out by one or more selected from dipping, roll coater, oiling roller, oiling guide, nozzle (spray) coating, and brush coating.

[0030] In the step (2), the heat treatment temperature is preferably 180 to 280 °C, more preferably 190 to 270 °C, even more preferably 200 to 260 °C, still more preferably 220 to 250 °C, and even more preferably 230 to 250 °C. When the heat treatment temperature exceeds the upper limit value, coloring occurs due to thermal decomposition. On the other hand, when the heat treatment temperature is less than the lower limit value, sufficient adhesiveness is not exhibited. When the heat treatment time exceeds the upper limit value, coloring occurs due to thermal decomposition. On the other hand, when the time is less than the lower limit, the adhesiveness may decrease.

[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, still more preferably 3 to 35 seconds, still more preferably 3 to 20 seconds, and still more preferably 3 to 10 seconds. In addition, when the heat treatment time is set to a short time of 30 seconds or less, it is also possible to perform the treatment online using a heat treatment furnace in the manufacturing process of polyvinyl alcohol-based fibers.

[0032] In the production of the surface-modified fiber, the above heat treatment may be performed only once, or may be performed two or more times while changing the treatment temperature and treatment time. However, when performing multiple heat treatments at a high temperature, the surface-modified layer may decompose, resulting in coloring or a decrease in adhesive strength.

[0033] <Physical properties of surface-modified fiber> In the present invention, surface-modified fibers having various shapes can be used according to 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, and more preferably 5 cN / dtex or more. Note that 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 it is preferably used in the form of a fiber cord, a woven fabric, a knitted fabric, etc. containing at least a part of the surface-modified fiber, and more preferably used as a woven fabric or a knitted fabric containing at least a part of the surface-modified fiber. For example, it can also be used as a surface-modified fiber to be embedded in a resin, cement, etc. as described later.

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

[0037] There is no particular limitation on the resin used in the molded article of the present invention. For example, 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-cyclohexyl dimethylene 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, polyphenylene sulfide (PPS) resin, modified polyphenylene ether (PPE) resin, polyetherimide (PEI) resin, polysulfone (PSF) resin, polyethersulfone (PES) resin, polyketone resin, polyarylate (PAR) resin, polyether nitrile (PEN) resin, polyether ketone (PEK) resin, polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyimide (PI) resin, polyamideimide (PAI) resin, fluorine (F) resin; liquid crystal polymer resins such as liquid crystal polyester resin; thermoplastic elastomers such as polystyrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, polyisoprene-based, or fluorine-based; or copolymer resins and modified resins thereof. These resins may be used alone or in combination of two or more. Among these, from the viewpoint of improving the adhesiveness with the surface-modified fiber, polyvinyl chloride resin is preferable.

[0038] The molded article of the present invention may be a fiber-reinforced resin in which the surface-modified fiber is mixed with a resin. As the resin used for the fiber-reinforced resin, the aforementioned resins can also be preferably used. When the molded article of the present invention is a fiber-reinforced resin, the content of the surface-modified fiber with respect to 100 parts by mass of the resin is preferably 0.1 to 50 parts by mass, and more preferably 1 to 30 parts by mass. When the blending amount of the surface-modified fiber with respect to the resin is within the above range, the dispersibility of the surface-modified fiber in the resin becomes good and an excellent reinforcing effect is exhibited.

[0039] There is no particular limitation on the method of incorporating the surface-modified fiber of the present invention into the resin. For example, a method of adding the surface-modified fiber to the pellets of the resin and uniformly mixing them can be mentioned. Also, there is no particular limitation on the manufacturing method of the fiber-reinforced resin, and molding methods such as melt extrusion molding and injection molding can be adopted.

[0040] The resin used for the molded article of the present invention may contain additives such as an impact resistance improver and an inorganic filler. Examples of the additives include a flame retardant, a conductivity-imparting agent, a crystal nucleating agent, an ultraviolet absorber, an antioxidant, a vibration damping material, an antibacterial agent, an insect repellent, an anti-odor agent, a coloring inhibitor, a heat stabilizer, a release agent, an antistatic agent, a lubricant, a coloring agent, and a foaming agent. When using the aforementioned additives, the content thereof is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the resin. When the content of the additives is within the above range, the effect of the additives can be obtained while maintaining the reinforcing effect by the surface-modified fiber.

Examples

[0041] Hereinafter, the present invention will be described more specifically with reference to examples and the like, but the present invention is not limited by such examples and the like. <Fiber> · Polyvinyl alcohol-based fiber (PVA) Manufactured by Kuraray Co., Ltd., Clarion 5501 (2000 dtex, 1000 f) · Polyamide fiber (PA) Melt-spun nylon 6 (1400 dtex, 204 f)

[0042] <Compound having a hydrogen-bonding functional group> [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 Nitto Boseki 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, an aqueous solution constituting the surface modification layer was similarly prepared using the compounds described in Table 1.

[0045] <Example 1> Polyvinyl alcohol-based fiber (PVA-based fiber) was immersed in an aqueous solution containing a compound having a hydrogen-bonding functional group, and then squeezed with a roller. The obtained fiber cord was dried at 140 °C for 30 seconds. Thereafter, heat treatment was performed at 240 °C for 5 seconds, and the surface-modified fiber was produced by winding it up.

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

[0047] The fibers obtained in the examples and comparative examples were evaluated according to the following method. The results are shown in Table 1. <Evaluation method> 〔Parameter (YI) of hue〕 For the obtained surface-modified fibers, the parameter (YI) of hue was measured using a haze meter SH7000 (manufactured by Nippon Electric Shokai Co., Ltd.) in accordance with JIS Z8722:2009. Incidentally, the values at three locations of the surface-modified fibers were measured, and the arithmetic mean value thereof was adopted as the parameter (YI) of hue. The results are shown in Table 1.

[0048] 〔Strength〕 In accordance with the test method of JIS L-1013:2010, the obtained surface-modified fibers were set with a yarn length of 20 cm, an initial load of 0.25 g / d, and a tensile speed of 50% / min, and the strength was measured in air at 20°C. The arithmetic mean of the five measurement values was adopted as the value of this evaluation. Incidentally, the fiber fineness (dtex) was determined by the mass method.

[0049] 〔Interfacial shear stress〕 An evaluation resin was prepared by adding 1% by mass of a curing agent to an unsaturated polyester resin (manufactured by Nippon Paint Co., Ltd.) and stirring. The obtained evaluation resin was adhered in a spherical shape so as to surround the obtained surface-modified fibers, and left at room temperature (20°C) for 2 hours. Thereafter, heat treatment was performed at 70°C for 2 hours. After measuring the fiber diameter and the axial length (resin diameter) of the obtained sample, it was fixed to a mount board, and the adhesive strength was measured with a testing machine (INSTRON "Universal Material Testing Machine 3365"), and the interfacial shear stress was calculated by the following formula. Interfacial shear stress (N / mm 2 ) = Maximum detected load (N) / (π × fiber diameter (mm) × axial length (mm))

[0050] 〔Process passability〕 In each of the examples and comparative examples, an aqueous solution containing a compound having a hydrogen-bonding functional group was adhered to each fiber, and after winding up 5 kg of the surface-modified fibers, the degree of contamination (gum-up) of the holding roller through which the surface-modified fibers passed was determined according to the following evaluation criteria. · Criteria G (good): There is no roller contamination due to gumming up, or the contamination is minimal, and there are no problems with the yarn manufacturing operability. B (bad): Roller contamination due to gumming up is significant, single yarn is taken during yarn manufacturing, there is winding, and there are problems with the yarn manufacturing operability.

[0051]

Table 1

[0052] <Examples 8 and 9> Surface-modified fibers were produced in the same manner as in Example 1, except that the compound having a hydrogen-bonding functional group described in Table 2 was used. Next, the obtained surface-modified fibers were twisted at 120 turns / m and aligned to 36 threads / inch to produce a reed-shaped sample. The sample and a soft polyvinyl chloride resin sheet were overlapped and heated at 1 MPa pressure and 160 °C for 10 minutes to obtain a test piece. The obtained 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 Testing Machine 3365"). The results are shown in Table 2. The measurement results indicate that the greater the numerical value, the greater the adhesive force between the surface-modified fiber and the polyvinyl chloride resin.

[0053] <Comparative Example 3> Samples were prepared in the same manner as in Example 8, except that the surface modification treatment was not performed, and the peel strength was measured. The results are shown in Table 2.

[0054]

Table 2

[0055] As is clear from the results of the examples and comparative examples, according to the present invention, it is possible to obtain surface-modified fibers that are excellent in adhesiveness and can suppress coloring.

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-modified fiber, characterized in that 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 fiber used as the raw material.

2. The hydrogen-bonding functional group is one or more 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. Surface-modified fiber according to claim 1.

3. The surface-modified fiber according to claim 1 or 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.

4. The surface-modified fiber according to any one of claims 1 to 3, wherein the hue parameter (YI) of the surface-modified fiber is 0 to 50.

5. 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.

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

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