Fiber bundling agent and fiber

Abstract

To provide a fiber bundling agent that allows suppression of crystallization in an aqueous solution state and exhibits superior bundling performance.SOLUTION: A fiber bundling agent includes an epoxy resin (A) represented by a chemical formula (1) and a nonionic surfactant (B). In the chemical formula (1), an epoxy resin (A1) in which n is 1, an epoxy resin (A2) in which n is 2, an epoxy resin (A3) in which n is 3, and an epoxy resin (A4) in which n is 4 are included. R1 is a C1-C3 alkylene group, and n is an integer of 0 or more and 20 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fiber bundling agent and fibers.

Background Art

[0002] A bundling agent is a chemical applied to fiber materials such as carbon fibers and is used for purposes such as suppressing damage to the fiber material and enhancing the bundling property of the fiber material.

[0003] Patent Document 1 discloses a fiber bundling agent composition containing a bisphenol type epoxy resin (A) represented by the following chemical formula (2) and a nonionic surfactant (B), wherein the bisphenol type epoxy resin (A) contains at least an epoxy resin (A1) in which n in the following chemical formula (2) is 0 or 1 and an epoxy resin (A2) in which n in the following chemical formula (2) is 2 or more, and n in the following chemical formula (2) per molecule of the bisphenol type epoxy resin (A) is 20 or less, the ratio (W1 / W2) of the total weight W1 of the epoxy resin (A1) in which n in the following chemical formula (2) is 0 or 1 to the total weight W2 of the epoxy resin (A2) in which n in the following chemical formula (2) is 2 or more is 15 / 85 to 90 / 10, and the bisphenol type epoxy resin (A) contains an epoxy resin in which n in the following chemical formula (2) is 0, an epoxy resin in which n in the following chemical formula (2) is 2, and an epoxy resin in which n in the following chemical formula (2) is 4 or more. A fiber bundling agent composition is described.

[0004]

Chemical Formula

[0005] In the formula, R 1 is each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 2 is each independently a structural moiety represented by either a methylene group or an isopropylidene group, and n is an integer of 0 or more.

[0006] The sizing agent described in Patent Document 1 was excellent in sizing property and also excellent in the adhesiveness between the fiber and the matrix resin.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] When the sizing agent described in Patent Document 1 was in an aqueous solution state, a part of the components of the sizing agent sometimes crystallized. If such crystallization occurred during the storage of the sizing agent, there were inconveniences such as it becoming difficult to use the sizing agent when in use.

[0009] Therefore, an object of the present invention is to provide a sizing agent for fibers that can suppress crystallization when in an aqueous solution state and is excellent in sizing property.

Means for Solving the Problems

[0010] The sizing agent for fibers according to the present invention for achieving the above object is a sizing agent for fibers containing an epoxy resin (A) represented by the following chemical formula (1) and a nonionic surfactant (B), and its characteristic configuration is that in the following chemical formula (1), it contains an epoxy resin (A1) where n is 1, an epoxy resin (A2) where n is 2, an epoxy resin (A3) where n is 3, and an epoxy resin (A4) where n is 4 When the total mass of the epoxy resin (A1) and the epoxy resin (A3) is W1, and the total mass of the epoxy resin (A2) and the epoxy resin (A4) is W2, the value of W1 / W2 is 0.15 or more and 5 or less. and is characterized in that.

[0011]

Chemical Formula

[0012] R 1 : An alkylene group having 1 to 3 carbon atoms n: An integer of 0 or more and 20 or less

[0013] According to this configuration, by containing all of the epoxy resins (A1) to (A4) where n is 1 to 4, the generation of crystals when the sizing agent is made into an aqueous solution can be effectively suppressed, and the sizing property of the fiber material can be realized at a high level.

[0014] A further characteristic configuration of the sizing agent for fibers according to the present invention lies in that the value of W1 / W2 is 0.3 or more and less than 2.

[0015] According to this configuration, the generation of crystals when the sizing agent is made into an aqueous solution can be further suppressed.

[0016] A further characteristic configuration of the sizing agent for fibers according to the present invention is that when the total content ratio of the epoxy resin (A) and the nonionic surfactant (B) is 100% by mass, the epoxy resin (A) is 10 mass % or more 90% by mass or less and the nonionic surfactant (B) is 10 mass % or more 90% by mass or less and they are contained in such proportions.

[0017] According to this configuration, the content ratios of the epoxy resin (A) and the nonionic surfactant (B) that can effectively suppress the generation of crystals when the sizing agent is made into an aqueous solution and can realize the sizing property of the fiber material at a high level can be defined.

[0018] A further characteristic configuration of the sizing agent for fibers according to the present invention is that it further contains at least one resin (C) selected from epoxy resins other than the epoxy resin (A), polyester resins, urethane resins, and vinyl ester resins.

[0019] According to this configuration, by containing any of the above resins (C), it becomes easier to impart sizing property to the fiber material.

[0020] A further characteristic configuration of the fiber sizing agent according to the present invention is that when the total content ratio of the epoxy resin (A), the nonionic surfactant (B), and the resin (C) is 100% by mass, the epoxy resin (A) is 10 mass % or more 90% by mass less than the nonionic surfactant (B) is 10 mass % or more 90% by mass less than and the resin (C) is 0 exceeding mass % 80% by mass or less and contained in these ratios.

[0021] According to this configuration, it is possible to effectively suppress crystal generation when the sizing agent is made into an aqueous solution, and it is possible to define the content ratios of the epoxy resin (A), the nonionic surfactant (B), and the resin (C) that can achieve a higher level of fiber material bundling property.

[0022] A characteristic configuration of the fiber according to the present invention is that the fiber sizing agent according to any one of the above is adhered thereto.

[0023] According to this configuration, the present invention is easily applicable to the reinforcement of composite materials having resins, ceramics, metals, etc. as base materials.

[0024] A further characteristic configuration of the fiber according to the present invention is that it is a reinforcing fiber.

[0025] According to this configuration, the present invention is even more easily applicable to the reinforcement of composite materials having resins, ceramics, metals, etc. as base materials.

[0026] A further characteristic configuration of the fiber according to the present invention is that the fiber sizing agent is adhered to carbon fiber or glass fiber.

[0027] According to this configuration, the present invention is particularly easily applicable to the reinforcement of composite materials having resins, ceramics, metals, etc. as base materials.

Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described. The fiber bundling agent of the present invention (hereinafter simply referred to as "bundling agent") is a fiber bundling agent containing an epoxy resin (A) represented by the following chemical formula (1) and a nonionic surfactant (B), and in the following chemical formula (1), it is characterized by containing an epoxy resin (A1) where n is 1, an epoxy resin (A2) where n is 2, an epoxy resin (A3) where n is 3, and an epoxy resin (A4) where n is 4.

[0029] [Chemical formula]

[0030] R 1 : An alkylene group having 1 to 3 carbon atoms n: An integer of 0 or more and 20 or less

[0031] The epoxy resin (A) represented by the above chemical formula (1) is a so-called bisphenol type epoxy resin produced by the condensation reaction of a bisphenol compound and epichlorohydrin. The epoxy resin (A) has various grades due to the difference in the repeating unit (n = 0, 1, 2,...).

[0032] In the present invention, an epoxy resin (A) where n is any integer from 1 to 4 is contained. That is, the bundling agent of the present invention contains all of an epoxy resin (A1) where n is 1, an epoxy resin (A2) where n is 2, an epoxy resin (A3) where n is 3, and an epoxy resin (A4) where n is 4. If this requirement is satisfied, the bundling agent of the present invention may contain other epoxy resins (A) with n, particularly n = 0.

[0033] Also, R 1 is an alkylene group having 1 to 3 carbon atoms, and can be, for example, a methylene group or an isopropylidene group.

[0034] The nonionic surfactant (B) can be any nonionic surfactant commonly used in the art. The nonionic surfactant (B) may be a single type of compound or a mixture of multiple types of compounds.

[0035] The nonionic surfactant (B) can be, for example, an alkylene oxide adduct of a compound having a hydroxy group. Examples of the compound having a hydroxy group include aromatic alcohols such as tristyrenated phenol, distyrenated phenol, and bisphenol A, and aliphatic alcohols such as dodecyl alcohol, isododecyl alcohol, tetradecyl alcohol, tridecyl alcohol, secondary dodecyl alcohol, secondary tridecyl alcohol, 2-ethylhexyl alcohol, oleyl alcohol, and isononyl alcohol. Among them, aromatic alcohols are preferred. Examples of the alkylene oxide include, but are not limited to, ethylene oxide and propylene oxide. Therefore, the nonionic surfactant (B) can preferably be an alkylene oxide adduct of an aromatic alcohol.

[0036] In the nonionic surfactant (B), a plurality of types of alkylene oxides may be used in combination. The added amount of the alkylene oxide can be, but is not limited to, 6 mol or more and 40 mol or less per mole of the nonionic surfactant (B).

[0037] The nonionic surfactant (B) may be a single type of compound or a mixture of a plurality of types of compounds.

[0038] It is considered that the aggregating agent crystallizes by the precipitation of the epoxy resin (A0). By containing all of the epoxy resins (A1) to (A4) as in the aggregating agent of the present invention, the molecular weight distribution becomes continuous (smooth), and it is considered that the precipitation of the epoxy resin (A0) becomes difficult. Therefore, by containing all of the epoxy resins (A1) to (A4) where n is 1 to 4 as in this configuration, the generation of crystals when the aggregating agent is made into an aqueous liquid can be effectively suppressed, and the aggregating property of the fiber material can be realized at a high level.

[0039] In the sizing agent of the present invention, when the total mass of epoxy resin (A1) and epoxy resin (A3) is W1 and the total mass of epoxy resin (A2) and epoxy resin (A4) is W2, the value of W1 / W2 is preferably 0.15 or more and 5 or less, and more preferably 0.3 or more and less than 2.

[0040] In this configuration, the mass ratio between the total mass W1 of epoxy resin (A1) and epoxy resin (A3) and the total mass W2 of epoxy resin (A2) and epoxy resin (A4) is defined.

[0041] In this configuration, the generation of crystals when the sizing agent is made into an aqueous solution can be further suppressed.

[0042] When the total content ratio of epoxy resin (A) and nonionic surfactant (B) in the sizing agent of the present invention is 100% by mass, the epoxy resin (A) is 10 mass % or more 90% by mass or less and the nonionic surfactant (B) is 10 mass % or more 90% by mass or less It is preferably contained in such proportions.

[0043] In this configuration, the generation of crystals when the sizing agent is made into an aqueous solution can be effectively suppressed, and the content ratios of epoxy resin (A) and nonionic surfactant (B) that can achieve a high level of bundling property of the fiber material can be defined.

[0044] The sizing agent of the present invention preferably further contains at least one resin (C) selected from epoxy resins other than the epoxy resin (A), polyester resins, urethane resins, and vinyl ester resins.

[0045] The epoxy resin may be, for example, the jER (registered trademark) series manufactured by Mitsubishi Chemical Corporation (such as jER (registered trademark) 828, jER (registered trademark) 834, jER (registered trademark) 1001, jER (registered trademark) 1002, jER (registered trademark) 1004, etc.), the NPES series manufactured by NAN YA PLASTIC CORPORATION (such as NPES301, NPES302, etc.), and the Sumiepoxy (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd. (such as Sumiepoxy (registered trademark) ELM-434, Sumiepoxy (registered trademark) ELM-100, etc.), etc., but is not limited thereto.

[0046] The polyester resin is a copolymer of a diol monomer and a dicarboxylic acid monomer. Therefore, the polyester resin has, in its molecule, a diol residue which is a partial structure derived from the diol monomer (which is a diol compound or its derivative), and a dicarboxylic acid residue which is a partial structure derived from the dicarboxylic acid monomer (which is a dicarboxylic acid or its derivative). The composition of the polyester resin is specified by the ratio (molar ratio) of the monomers constituting the molecule.

[0047] As the diol monomer constituting the polyester resin, one or more kinds of diol compounds may be included. Examples of the diol compound include ethylene glycol, diethylene glycol, bisphenol A, an ethylene oxide adduct of bisphenol A (the Newpole (registered trademark) BPE series manufactured by Sanyo Chemical Industries, Ltd. (such as Newpole (registered trademark) BPE-20, Newpole (registered trademark) BPE-40, Newpole (registered trademark) BPE-100, etc.)), a propylene oxide adduct of bisphenol A (the Newpole (registered trademark) BP series manufactured by Sanyo Chemical Industries, Ltd. (such as Newpole (registered trademark) BP-2P, Newpole (registered trademark) BP-3P, Newpole (registered trademark) BP-5P, etc.)), etc., but is not limited thereto.

[0048] As the dicarboxylic acid monomer constituting the polyester resin, one or more kinds of dicarboxylic acid compounds may be included. Examples of the dicarboxylic acid compounds include, but are not limited to, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, alkali metal salts of 5-sulfoisophthalic acid (sodium salt, potassium salt, lithium salt, etc.).

[0049] Non-limiting examples of the polyester resin include a copolymer of diethylene glycol, isophthalic acid, and sodium 5-sulfoisophthalate, a copolymer of ethylene glycol, diethylene glycol, isophthalic acid, terephthalic acid, and sodium 5-sulfoisophthalate, a copolymer of an ethylene oxide adduct of bisphenol A and fumaric acid (in other words, a copolymer of bisphenol A, ethylene glycol, and fumaric acid), a copolymer of an ethylene oxide adduct of bisphenol A and maleic acid (in other words, a copolymer of bisphenol A, ethylene glycol, and maleic acid). Note that the polyester resin may be a single compound or a mixture of multiple compounds.

[0050] The urethane resin can be, for example, DISPERCOLL U 54 (manufactured by Covestro), Superflex 500M (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Superflex 650 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Superflex 860 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Superflex E-2000 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), etc., but is not limited thereto.

[0051] The vinyl ester resin can be, for example, a reaction product of any of the epoxy resins exemplified above and methacrylic acid. In addition, the quantitative ratio of the reaction substrates when producing the reaction product may be such that the epoxy value of the epoxy resin is equal to the acid value of methacrylic acid, or either one may be made larger.

[0052] By containing any of the above resins (C), it becomes easier to impart cohesiveness to the fiber material.

[0053] When the total content ratio of the epoxy resin (A), nonionic surfactant (B), and resin (C) of the sizing agent of the present invention is 100% by mass, the epoxy resin (A) is 10 mass % or more to 90% by mass less than , the nonionic surfactant (B) is 10 mass % or more to 90% by mass less than and the resin (C) is 0 exceeding mass % to 80% by mass or less and is preferably contained in such a ratio.

[0054] According to this configuration, it is possible to effectively suppress crystal generation when the sizing agent is made into an aqueous liquid, and it is possible to define the content ratios of the epoxy resin (A), nonionic surfactant (B), and resin (C) that can achieve a higher level of the sizing property of the fiber material.

[0055] (Other components) The sizing agent according to the present embodiment may contain other components in addition to the epoxy resin (A), nonionic surfactant (B), and resin (C). Examples of such other components include preservatives, antistatic agents, antioxidants, ultraviolet absorbers, defoaming agents (such as modified silicone), resins other than resin (C), etc., but are not limited thereto.

[0056] Further, as a typical mode when the sizing agent is used for sizing treatment of the fiber material, a mode in which the non-volatile component such as the epoxy resin (A) is diluted with a diluent (generally also referred to as a sizing solution) is exemplified. Such a diluent is also an example of other components. Examples of the diluent include water (tap water, industrial water, ion-exchanged water, distilled water, etc.), acetone, methyl ethyl ketone, N-methyl-2-pyrrolidone, etc., but are not limited thereto. Note that the concentration of the non-volatile component in the sizing agent in the mode where the non-volatile component is diluted with a diluent is not particularly limited, but can be, for example, 10% by mass or more and 60% by mass or less. The non-volatile component of the sizing agent refers to the component that remains without volatilizing after heating the sizing agent in a hot air dryer at 105 °C for 2 hours, and the concentration thereof refers to the ratio of the mass of the non-volatile component in the sizing agent to the mass of the sizing agent.

[0057] 〔Manufacturing method of sizing agent〕 The sizing agent according to this embodiment can be obtained by mixing an epoxy resin (A), a nonionic surfactant (B), and optionally added components by a known method. For example, it can be produced by adding water over 5 hours while stirring the epoxy resin (A), the nonionic surfactant (B), and optionally added components at a temperature between 20°C and 90°C.

[0058] 〔Method of using the sizing agent〕 The sizing agent according to this embodiment is used for sizing treatment of fiber materials. The sizing treatment is a treatment for attaching the sizing agent to the fiber material, and as the method, a method usually used in the art for attaching this type of sizing agent to the fiber material can be applied. That is, an immersion oiling method, a spray oiling method, a roller oiling method, a guide oiling method, etc. can be adopted. In addition, when applying each method, the sizing agent can be appropriately diluted with a diluent such as water.

[0059] The adhesion amount of the sizing agent to the fiber material is not particularly limited. For example, it is preferable that the sizing agent adheres in an amount of 0.1% by mass or more and 3% by mass or less based on the entire fiber material to which the sizing agent has adhered.

[0060] When the sizing agent according to this embodiment is applied during the production of reinforcing fibers, reinforcing fibers to which the sizing agent has adhered to the fiber material can be obtained. These reinforcing fibers are an example of the fibers according to the present invention. The fiber material is preferably an inorganic fiber, and in this case, the reinforcing fiber is an inorganic fiber to which the sizing agent has adhered. Further, it is more preferable that the inorganic fiber is a carbon fiber or a glass fiber.

[0061] These reinforcing fibers can be used in composite materials having a base material such as resin, ceramic, or metal. A composite material characterized by including the above-mentioned reinforcing fibers and a matrix resin which is a thermosetting resin is an embodiment of the present invention.

[0062] 〔Other embodiments〕 The fiber bundling agent according to the present invention is a fiber bundling agent containing an epoxy resin (A) represented by the following chemical formula (1) and a nonionic surfactant (B). In the following chemical formula (1), it may contain an epoxy resin (A1) where n is 1, an epoxy resin (A2) where n is 2, an epoxy resin (A3) where n is 3, and an epoxy resin (A4) where n is 4.

Chemical formula

[0063] According to this configuration, by containing all of the epoxy resins (A1) to (A4) where n is 1 to 4, the generation of crystals when the bundling agent is made into an aqueous solution can be effectively suppressed, and the bundling property of the fiber material can be realized at a high level.

[0064] Regarding other configurations as well, it should be understood that all the embodiments disclosed in this specification are illustrative in all respects and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications can be made without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are of course included in the scope of the present invention.

Example

[0065] 〔Example 1〕 The epoxy resin (bisphenol type epoxy resin) (A) represented by the above chemical formula (1) was produced by the following method.

[0066] 400 g of jER1001 (manufactured by Mitsubishi Chemical Corporation) as an epoxy resin was dissolved in tetrahydrofuran so that the solid content concentration became 2%. The epoxy resin was fractionated by molecular weight using a GPC fractionation device [Recycling fractionation HPLC, "LC-9130NEXT" manufactured by Nippon Analytical Industry Co., Ltd.]. Thereafter, each fractionated solution was charged into a reaction vessel (glass four-necked flask reaction vessel) equipped with a heating and cooling device and a stirring device, and the pressure was gradually reduced to 20 mmHg at 90 °C to remove tetrahydrofuran, thereby obtaining the following compounds (A0-1) to (A5-1) (epoxy resins).

[0067] · Bisphenol type epoxy resin (A0-1) (molecular weight 340) in which n in chemical formula (1) is 0 · Bisphenol type epoxy resin (A1-1) (molecular weight 624) in which n in chemical formula (1) is 1 · Bisphenol type epoxy resin (A2-1) (molecular weight 908) in which n in chemical formula (1) is 2 · Bisphenol-type epoxy resin (A3-1) with n = 3 in Chemical Formula (1) (molecular weight 1192) · Bisphenol-type epoxy resin (A4-1) with n = 4 in Chemical Formula (1) (molecular weight 1476) · Bisphenol-type epoxy resin (A5-1) with n being 5 or more and 10 or less in Chemical Formula (1) (molecular weight 1760 or more)

[0068] The epoxy resins (A0-1) to (A5-1) are each a compound in which R 1 in Chemical Formula (1) is an isopropylidene group.

[0069] 〔Example 2〕 The focusing agent of the present invention was produced by the above method for producing a focusing agent (Examples 1 to 11 of the present invention). That is, it was produced by adding water over 5 hours while stirring the epoxy resin (A), the nonionic surfactant (B), and optionally added components at a temperature between 20°C and 90°C. In Examples 1 to 11 and Reference Example 1 of the present invention, the epoxy resin contains epoxy resins (A0-1) to (A5-1), and the nonionic surfactant (B) contains at least any one of (B-1) to (B-3) shown below.

[0070] (B-1): A compound obtained by adding 30 moles of ethylene oxide and 6 moles of propylene oxide to 1 mole of tristyrenated phenol (B-2): A compound obtained by adding 27 moles of ethylene oxide to 1 mole of tristyrenated phenol (B-3): A compound obtained by adding 18 moles of ethylene oxide to 1 mole of bisphenol A

[0071] Also, in Examples 1 to 5 of the present invention, the resin (C) contains any one of (EP-1), (PE-1), (PE-2), (PU-1), and (VE-1) shown below.

[0072] (EP-1): Sumiepoxy (registered trademark) ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.) (epoxy resin other than epoxy resin (A)) (PE-1): A polyester resin with a molar ratio of 5-sodium sulfoisophthalic acid: isophthalic acid: diethylene glycol of 4:46:50 and a number average molecular weight of 15,000 (PE-2): A polyester resin produced by reacting fumaric acid with Newpol BPE-20 (manufactured by Sanyo Chemical Industries, Ltd.) in a molar ratio of 3:4 (PU-1): A urethane resin that is the non-volatile resin portion of DISPERCOLL U 54 (manufactured by Covestro) (VE-1): A vinyl ester resin produced by reacting jER828 (manufactured by Mitsubishi Chemical Corporation) with methacrylic acid in a molar ratio of 1:2

[0073] The mass percentages (total 100 mass%) of the epoxy resins (A0-1) to (A5-1), non-ionic surfactant (B), and resin (C) in Invention Examples 1 to 5 of the present invention are shown in Table 1-1, and the mass percentages (total 100 mass%) of the epoxy resins (A0-1) to (A5-1) and non-ionic surfactant (B) in Invention Examples 6 to 11 and Reference Example 1 are shown in Tables 1-1 to 1-2. For example, the proportion of each component in Invention Example 1 of the present invention is: epoxy resin (A0-1): 25 mass%, epoxy resin (A1-1): 10 mass%, epoxy resin (A2-1): 8 mass%, epoxy resin (A3-1): 6 mass%, epoxy resin (A4-1): 4 mass%, epoxy resin (A5-1): 5 mass%, non-ionic surfactant (B-1): 22 mass%, resin (EP-1): 20 mass%.

[0074] Also, when the total mass of epoxy resin (A1-1) and epoxy resin (A3-1) is W1, and the total mass of epoxy resin (A2-1) and epoxy resin (A4-1) is W2, the values of W1 / W2 are shown in Tables 1-1 and 1-2.

[0075]

Table 1-1

[0076]

Table 1-2

[0077] The flocculants of the comparative examples were produced by the above-described method for producing a flocculant (Comparative Examples 1 and 2). In Comparative Example 1, the epoxy resin (A) contains epoxy resins (A0-1), (A2-1) to (A5-1), and the nonionic surfactant (B) contains (B-1). In Comparative Example 2, the epoxy resin contains epoxy resins (A0-1) to (A2-1), and the nonionic surfactant (B) contains (B-1). Table 1-2 shows the mass percentages of the epoxy resin (A) and the nonionic surfactant (B) in Comparative Examples 1 and 2 (total 100% by mass).

[0078] <Evaluation Method> Regarding the above Examples 1 to 11, Reference Example 1, and Comparative Examples 1 and 2, the crystal inhibition property and the flocculation property of the flocculant were evaluated.

[0079] For the crystal inhibition property, 100 mL of a 30% by mass aqueous solution of the flocculant in each Example of the present invention and each Comparative Example was prepared, sealed in a transparent glass bottle with a volume of 140 mL, and allowed to stand at 0°C for 10 days. Then, the crystalline deposits accumulated at the bottom were evaluated according to the following criteria.

[0080] S: No crystalline deposits were observed, and the crystal inhibition property was very good. A: Crystalline deposits were deposited on the bottom of the glass bottle, but the area was less than 10% of the bottom area, and the crystal inhibition property was good. B: Crystalline deposits were deposited on the bottom of the glass bottle, but the area was 10% or more and less than 20% of the bottom area, and the crystal inhibition property was at an acceptable level. C: A large amount of crystalline deposits were deposited on the bottom of the glass bottle, occupying 20% or more of the bottom area, and the crystal inhibition property was poor.

[0081] For the bundling property, a sizing bath was filled with a sizing solution containing a bundling agent in each inventive example and each comparative example (nonvolatile content concentration 4%), and the bundling agent was applied to the sizing bath by passing a fiber material (carbon fiber or glass fiber) through the sizing bath. After the bundling agent was applied, the roll of the fiber material was set on a creel and unwound at a speed of 5 m per minute, and the state of the fiber material when passing through the roller immediately after unwinding was observed. According to the observation results, the bundling property of the fiber material brought about by the bundling agent in each inventive example and each comparative example was evaluated in the following three stages.

[0082] A: Almost no fiber material wound around the roller was seen, and the aggregation of the passed fiber material was good. B: A slight amount of fiber material wound around the roller was seen, but the aggregation of the passed fiber material was good. C: A large amount of fiber material wound around the roller was seen, and the passed fiber material was scattered.

[0083] <Evaluation Results> Regarding the crystal inhibition property and bundling property of each inventive example and each comparative example, the evaluation results are shown in Tables 1-1 to 1-2.

[0084] In terms of crystal inhibition property, for Inventive Examples 1 to 8, an S evaluation (very good), for Inventive Examples 9 to 11, an A evaluation (good), Reference Example 1 and for [comparative example] 11 an B evaluation (acceptable level) was obtained respectively. That is, for Inventive Examples 1 to

[0085] it was recognized that the crystals could be effectively inhibited. Reference Example 1 At this time, the value of W1 / W2 was 0.333 to 1.875 in Inventive Examples 1 to 8 (S evaluation), 0.208 to 4.667 in Inventive Examples 9 to 11 (A evaluation),

[0086] and 5.429 in [comparative example] (B evaluation).

[0087] The bundling agent of the present invention (Inventive Examples 1 to 11) contains all of the epoxy resins (A1-1) to (A4-1). In contrast, Comparative Example 1 does not contain the epoxy resin (A1-1), and Comparative Example 2 does not contain the epoxy resins (A3-1) and (A4-1). The aggregating agent is considered to crystallize by precipitation of the epoxy resin (A0-1). From the above results, by containing all of the epoxy resins (A1-1) to (A4-1) like the aggregating agent of the present invention, the molecular weight distribution becomes continuous (smooth) compared to each comparative example, and it is considered that the epoxy resin (A0-1) is less likely to precipitate.

[0088] The values of W1 / W2 were 0.125 and 2.000 in Comparative Examples 1 and 2, respectively.

[0089] From the above, it was recognized that the lower limit of W1 / W2 is greater than 0.125, for example, 0.15, and preferably 0.3. Also, it was recognized that the upper limit of W1 / W2 is 5.429 or less, for example, 5.000 or less, and preferably less than 2.000.

[0090] That is, it was found that if the value of W1 / W2 is 0.15 or more and 5 or less, crystal generation can be further suppressed, which is preferable, and if the value of W1 / W2 is 0.3 or more and less than 2, crystal generation can be further suppressed, which is more preferable.

[0091] In terms of aggregating property, for Invention Examples 1 to 5, A evaluation (almost no winding was observed), and for Invention Examples 6 to 11 and Reference Example 1 for which B evaluation (slight winding was observed) was obtained respectively. That is, for Invention Examples 1 to 11 it was above the allowable level.

[0092] At this time, in Invention Examples 1 to 5, they contain the epoxy resin (A), the nonionic surfactant (B), and the resin (C), and in Invention Examples 6 to 11 and Reference Example 1 they contain the epoxy resin (A) and the nonionic surfactant (B).

[0093] That is, by containing any of the above resins (C) as in Invention Examples 1 to 5 (A evaluation), it was found that the fiber material was more likely to be imparted with aggregability than when the resin (C) was not contained (Invention Examples 6 to 11 and Reference Example 1 ).

[0094] In Invention Examples 6 to 11 and Reference Example 1 , the total content ratio of the epoxy resin (A) and the nonionic surfactant (B) was 100% by mass. That is, in Invention Examples 6 to 11 and Reference Example 1 , the content ratio of the epoxy resin (A) was 67 to 76% by mass, and the content ratio of the nonionic surfactant (B) was 24 to 33% by mass.

[0095] It was recognized that when the content ratio of each component satisfied the above requirements, the generation of crystals when the aggregating agent was made into an aqueous solution could be effectively suppressed, and the aggregability of the fiber material could be realized at a high level.

[0096] When the total content ratio of the epoxy resin (A) and the nonionic surfactant (B) was 100% by mass (Invention Examples 6 to 11 and Reference Example 1 ), if the epoxy resin (A) was contained in a ratio of 10 to 90% by mass and the nonionic surfactant (B) was contained in a ratio of 10 to 90% by mass, it was considered that the same effects as above could be obtained.

[0097] In Invention Examples 1 to 5, the total content ratio of the epoxy resin (A), the nonionic surfactant (B), and the resin (C) was 100% by mass. That is, in Invention Examples 1 to 5, the content ratio of the epoxy resin (A) was 18 to 58% by mass, the content ratio of the nonionic surfactant (B) was 15 to 30% by mass, and the content ratio of the resin (C) was 20 to 52% by mass.

[0098] It was recognized that when the content ratio of each component satisfied the above requirements, the generation of crystals when the aggregating agent was made into an aqueous solution could be effectively suppressed, and the aggregability of the fiber material could be realized at an even higher level.

[0099] When the total content ratio of the epoxy resin (A), nonionic surfactant (B), and resin (C) is 100% by mass, if the epoxy resin (A) is contained in a proportion of 10 to 90% by mass, the nonionic surfactant (B) is contained in a proportion of 10 to 90% by mass, and the resin (C) is contained in a proportion of 0 to 80% by mass (excluding 0), it is considered that the same effect as described above can be obtained.

Industrial Applicability

[0100] The present invention can be used, for example, for sizing treatment of fiber materials.

Claims

1. A sizing agent for fibers containing an epoxy resin (A) represented by the following chemical formula (1) and a nonionic surfactant (B), The sizing agent for fibers is characterized by containing an epoxy resin (A1) where n is 1, an epoxy resin (A2) where n is 2, an epoxy resin (A3) where n is 3, and an epoxy resin (A4) where n is 4 in the following chemical formula (1). 【Chemical 1】 R １ : An alkylene group having 1 to 3 carbon atoms n: An integer from 0 to 20

2. The sizing agent for fibers according to Claim 1, where when the total mass of the epoxy resin (A1) and the epoxy resin (A3) is W1, and the total mass of the epoxy resin (A2) and the epoxy resin (A4) is W2, the value of W1 / W2 is 0.15 or more and 5 or less.

3. The sizing agent for fibers according to Claim 2, where the value of W1 / W2 is 0.3 or more and less than 2.

4. The sizing agent for fibers according to Claim 1, where when the total content ratio of the epoxy resin (A) and the nonionic surfactant (B) is 100% by mass, the epoxy resin (A) is contained in a ratio of 10 to 90% by mass, and the nonionic surfactant (B) is contained in a ratio of 10 to 90% by mass.

5. The sizing agent for fibers according to Claim 1, further containing at least one resin (C) selected from epoxy resins other than the epoxy resin (A), polyester resins, urethane resins, and vinyl ester resins.

6. The sizing agent for fibers according to Claim 5, where when the total content ratio of the epoxy resin (A), the nonionic surfactant (B), and the resin (C) is 100% by mass, the epoxy resin (A) is contained in a ratio of 10 to 90% by mass, the nonionic surfactant (B) is contained in a ratio of 10 to 90% by mass, and the resin (C) is contained in a ratio of 0 to 80% by mass (excluding 0).

7. A fiber characterized by having the sizing agent for fibers according to any one of Claims 1 to 6 attached thereto.

8. The fiber according to Claim 7, which is a reinforcing fiber.

9. The fiber according to Claim 7, where the sizing agent for fibers is attached to carbon fiber or glass fiber.

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