Carboxylate salts of amine compounds as curing agents

Abstract

A sizing composition, more specifically a sizing composition comprising epoxy and amine compound carboxylates for the treatment of carbon fibers, is provided. The structure of the amine used to prepare the carboxylate is R n X m Q is an amine-containing group, X is a polyether group, and R is a linear or branched saturated or unsaturated aryl group or alkyl group, or a combination thereof. m and n are integers greater than or equal to 0. The composition reduces or eliminates the gloss and sheen of the carbon fibers in the finished product. Carbon fiber reinforced composite materials and carbon fibers incorporating the sizing composition are also provided.

Description

【Technical Field】 【0001】 Cross - Reference to Related Applications This application claims the priority and benefit of U.S. Provisional Application No. 63 / 380,657, filed on October 24, 2022, the entire disclosure of which is incorporated herein by reference for all purposes. 【0002】 Technical Field The present invention generally relates to sizing compositions, and more particularly to sizing compositions containing carboxylates of epoxy - containing resins and amine compounds as latent epoxy cures for treating carbon fibers. 【Background Art】 【0003】 Carbon fibers have been used in a wide variety of structural applications and industries due to their desirable properties. For example, carbon fibers can be formed into structural components that combine high strength and high stiffness while being significantly lighter than metal components with equivalent properties. One common method of preparing carbon fibers involves converting precursor fibers in a multi - step process that includes heating, oxidizing, and carbonizing polyacrylonitrile (PAN) precursor fibers to produce fibers that are more than 90% carbon. The resulting carbon fibers are formed into high - strength composite materials for structural applications, used in their pure form for electrical and frictional applications, or further processed for use as adsorbents, filters, or other applications. In particular, composite materials in which carbon fibers function as reinforcements in resin, ceramic, or metal matrices have been developed. 【0004】 At the end of the carbon fiber manufacturing process, a sizing material is typically applied to the carbon fibers. This sizing material, also called sizing or simply size, helps protect the carbon fiber filaments during subsequent handling, weaving, and processing. Sizing can also provide compatibility with matrix resins used in the process of manufacturing composite materials. 【0005】 In many cases, in the cosmetic applications of carbon fiber prepregs and woven fabrics, the appearance of these carbon-based materials is of utmost importance and may exceed the strength performance and other mechanical properties of composites. As used herein, the term "cosmetic application" refers to an application where the customer can observe the appearance of carbon fibers in the final product. Examples of such applications can be found in carbon fiber-based woven fabrics or prepregs used in household appliances (such as laptop bodies), automotive applications, and sports goods. The occurrence of various visual defects is well-known in this field of application and is highly undesirable. One such defect is referred to herein as a "stripe" and appears as an obvious difference in the variation of darkness at the tow level from one tow to another, which is particularly evident in woven goods. 【0006】 There are several plausible causes for such variations within the material, some of which may be due to contamination (mixing in), variations in the sizing amount of the fibers, etc. Whether these causes are natural or unnatural, such variations in the appearance of the fibers in the finished product are highly undesirable. These effects are particularly pronounced in fibers having a brighter / glossier appearance due to the high luster or sheen of the fibers. Therefore, in such applications, it is advantageous to remove the luster or sheen of the carbon fiber tow. Furthermore, for aesthetic reasons, the appearance of the fiber or fiber fabric product may desirably be as dark as possible without luster in some cases. 【0007】 Therefore, there is still a need for an improved sizing agent composition that can eliminate luster or sheen and improve the uniformity between carbon fiber tows in the composite material. SUMMARY OF THE INVENTION 【0008】 Surprisingly, it has been found that by combining an epoxy-containing size with a carboxylate of an amine and curing / drying at a specific temperature on carbon fibers, the cosmetic appearance of the carbon fibers and composite materials containing the carbon fibers can be improved. 【0009】 One embodiment of the present invention is 【0010】 Epoxy-containing resin and 【0011】 A sizing composition comprising an amine carboxylate, wherein the amine is of the formula 【0012】 R n X m Q And, 【0013】 During the ceremony, 【0014】 Q is an amine-containing group comprising at least one primary or secondary amine, 【0015】 X is a polyether group selected from the group consisting of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO), or mixtures thereof. 【0016】 m is an integer, and m ≥ 0. 【0017】 R is an aryl or alkyl group, each alkyl group may independently be linear or branched, each alkyl group may independently be saturated or unsaturated, R contains 0 to 10 heteroatoms, and R is unsubstituted or C1 to C 12 Alkyl alkyl groups, C1-C 12 Heteroalkyl groups, C6-C 14 Aryl group and C6~C 14 It is either substituted with 1 to 5 substituents selected from the group consisting of heteroaryl groups, 【0018】 n is an integer, and n ≥ 0. 【0019】 Another embodiment of the present invention is a carbon fiber prepared by drying and curing the above-described composition on its surface. 【0020】 Another embodiment of the present invention is a method for treating carbon fibers, comprising applying the above-described sizing composition to the carbon fibers and forming a coating thereon. 【0021】 Another embodiment of the present invention is a carbon fiber reinforced composite material containing the carbon fibers described above. [Brief explanation of the drawing] 【0022】 [Figure 1] Figure 1 shows a comparison of grayscale dark values ​​at different observation angles for control fibers and specific darker experimental fibers. 【0023】 [Figure 2] Figure 2 shows the different zones within each fiber used to calculate the median grayscale value for comparison. [Modes for carrying out the invention] 【0024】 The present invention will be described in more detail below. These inventions may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, but rather these embodiments are provided to satisfy the legal requirements to which this disclosure is applicable. Similar numbers refer to similar elements throughout. Where used herein and in the appended claims, the singular forms “a,” “an,” and “the” include multiple subjects unless the context clearly indicates otherwise. All patents and patent application publications are incorporated herein by reference in their entirety. 【0025】 I. Definition 【0026】 For the purposes of this application, the following terms shall have the meanings set forth below. 【0027】 The terms “sizing material,” “sizing agent,” “sizing,” and “size” refer to materials applied to carbon fibers for the purpose of 1) improving the handling, weaving, and / or processing of carbon fibers, and / or 2) improving the compatibility of carbon fibers with the matrix in composite materials. 【0028】 The term "fiber" can refer to a fiber of finite length or a filament of infinite length. 【0029】 The term "precursor fiber" refers to a fiber containing a polymer material that, upon sufficient heat application, can be converted into a carbon fiber having a carbon content of approximately 85% by weight or more, particularly approximately 95% by weight or more. Precursor fibers may include both homopolymers and copolymers of acrylonitrile (AN), and may also include vinyl copolymers such as methyl acrylate (MA), methacrylic acid (MAA), sodium methallyl sulfonate, itaconic acid (IA), vinyl bromide (VB), isobutyl methacrylate (IBMA), and combinations thereof. In one embodiment, the precursor fiber includes a polyacrylonitrile (PAN) polymer formed mainly from acrylonitrile monomers. 【0030】 The term "grayscale" is a numerical method that describes the darkness of an object on a scale from 0 (black) to 255 (white). The numbers between these values ​​represent various shades of gray, with numbers closer to 0 being darker and numbers closer to 255 being lighter. 【0031】 PAN precursor fibers are typically prepared by melt spinning or by solvating the precursor polymer in organic and / or inorganic solvents such as dimethyl sulfoxide, dimethylformamide, zinc chloride, or sodium thiocyanate to form a spinning solution. For example, the spinning solution may be formed from water, acrylonitrile polymer, and sodium thiocyanate in exemplary weight ratios of about 60:10:30. This solution can then be concentrated by evaporation and filtered to obtain the spinning solution. The spinning solution is passed through a spinneret using various spinning processes such as dry, dry / wet, or wet spinning to form polyacrylonitrile precursor fibers. After exiting the spinneret, the spun filaments are washed. In some embodiments, the spun filaments may be stretched to several times their original length in hot water and steam. After the fibers are washed, before and / or after stretching, the fibers are typically subjected to a finishing step, where they are spin-finished to protect them in subsequent processing steps. 【0032】 As used herein, the terms “about” and “substantially” mean deviations (plus or minus) of less than 10% of the listed values, in particular less than 5%, less than 4%, less than 3%, and less than 2%.

[0001] Where a parameter range is provided, it is understood that all integers and ranges within that range, as well as 1 / 10 and 1 / 100 of them, are also provided by the embodiment. For example, "5-10%" includes 5%, 6%, 7%, 8%, 9%, and 10%, 5.0%, 5.1%, 5.2%....9.8%, 9.9%, and 10.0%, as well as 5.00%, 5.01%, 5.02%....9.98%, 9.99%, and 10.00%, as well as, for example, 6-9%, 8-10%, 5.1%-9.9%, and 5.01%-9.99%. Similarly, where a list is presented, it should be understood that each individual element of that list, and all combinations of its components, are separate embodiments unless otherwise specified. For example, "1, 2, 3, 4, and 5" encompasses, in numerous embodiments, 1, 2, 3; 1 and 2; 3 and 5; 1, 3, and 5; and 1, 2, 4, and 5. 【0033】 The term "carboxylate salt" of an amine refers to a compound produced by reacting a carboxylic acid with an amine-containing compound. As used herein, it means that all primary and / or secondary amines present have been reacted and converted to their corresponding carboxylate salts. 【0034】 The term "epoxy-containing resin" refers to any resin made from monomers containing at least one epoxide group. In one embodiment, the epoxy-containing resin is an epoxy resin. 【0035】 One embodiment of the present invention is 【0036】 Epoxy-containing resin and 【0037】 A sizing composition comprising an amine carboxylate, wherein the amine is of the formula 【0038】 R n X m Q And, 【0039】 During the ceremony, 【0040】 Q is an amine-containing group containing at least one primary or secondary amine, 【0041】 X is a polyether group selected from the group consisting of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO), or a mixture thereof, 【0042】 m is an integer and m≥0, 【0043】 R is an aryl or alkyl group, each alkyl group may independently be linear or branched, each alkyl group may independently be saturated or unsaturated, R contains 0 to 10 heteroatoms, and R is either unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of C1-C 12 alkyl group, C1-C<00000​​​​​​​​​​​​​​​​​​​​​​​​​​​​In one embodiment, at least one R is linear. In one embodiment, at least one R is branched. In one embodiment, at least one R is saturated. In one embodiment, at least one R is unsaturated. In one embodiment, R is unsubstituted. In one embodiment, R is substituted. 【0050】 In one embodiment, n ≥ 2 or n ≥ 3. In one embodiment, n is between 0 and 20. In one embodiment, n is at least, at most, or within the range defined by approximately 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, or any two of these values. 【0051】 In one embodiment, the carboxylate salt is derived from a monocarboxylic acid. In one embodiment, the carboxylate salt is derived from a polycarboxylic acid. In one embodiment, the carboxylate salt is derived from a polycarboxylic acid derivative having at least one free / undenatured acid group. 【0052】 One embodiment of the present invention is a carbon fiber prepared by drying and curing the above-described composition on a surface. After drying and curing, the carboxylate salt may not be present in the coating. Another embodiment of the present invention is a carbon fiber reinforced composite material containing the above-described carbon fiber. In one embodiment, the carbon fiber reinforced composite material includes a resin matrix injected into the fibers. 【0053】 One embodiment of the present invention is a method for preparing treated carbon fibers, the method comprising forming treated carbon fibers, i) The step of applying the above-mentioned sizing composition to carbon fibers to form coated carbon fibers, ii) A step of drying the coated carbon fiber, iii) A step of curing the coated carbon fiber Includes. 【0054】 Step i) is generally carried out at room temperature (about 20-25°C) or near room temperature, but this is not a requirement. Step i) is also typically carried out by immersing a fabric containing fibers or multiple fibers in a bath containing a sizing composition. In one embodiment, step i) is carried out for about 5 seconds to about 60 seconds. In one embodiment, step i) is carried out for at least, at most, or within a range defined by about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 seconds, or any two of these values. 【0055】 In one embodiment, step ii) is carried out at a temperature of about 100°C to about 190°C. In one embodiment, step ii) is carried out at a temperature of at least, at most, or within a range defined by any two of these values: at least, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, or 190°C. 【0056】 In one embodiment, step ii) is performed for about 15 seconds to about 5 minutes. In one embodiment, step ii) is performed for at least, at most, or within a range defined by about 15 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, or 5 minutes, or any two of these values. 【0057】 In one embodiment, step iii) is carried out at a temperature of approximately 100°C to approximately 190°C. In one embodiment, step iii) is carried out at a temperature of at least, at most, or within the range defined by any two of these values: at a temperature of approximately 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, or 190°C. The term "curing" does not require 100% curing and includes partial curing. 【0058】 In one embodiment, step iii) is performed for approximately 15 seconds to approximately 5 minutes. In one embodiment, step iii) is performed for at least, at most, or within a range defined by approximately 15 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, or 5 minutes, or any two of these values. 【0059】 In one embodiment, steps ii) and iii) are performed simultaneously. In one embodiment, steps ii) and iii) are performed sequentially (for example, when the coated fibers are dried at a temperature below the temperature required for curing). If step i) is performed by immersing a carbon fiber or a fabric containing multiple carbon fibers in a bath containing a sizing solution, the fiber or fabric is removed from the bath before performing steps ii) and iii). 【0060】 1. Epoxy resin 【0061】 The epoxy resin used in the sizing composition of the present invention may be any epoxide-containing material known in the art. In one embodiment, the epoxy resin is an epoxy-containing copolymer such as epoxy methacrylate, epoxy acrylate, epoxy ester, and siloxane epoxy copolymer. In one embodiment, the epoxy-containing copolymer is an epoxy / urethane copolymer. 【0062】 Examples of suitable epoxys include those disclosed in U.S. Patent Nos. 4,409,288 and 6,013,730, and U.S. Patent Application Publication No. 2013 / 0224470, which are incorporated herein by reference in their entirety. In one embodiment, the epoxy resin is bisphenol-based. In one embodiment, the epoxy resin is bisphenol A-based. In one embodiment, the epoxy resin is bisphenol F-based. In one embodiment, the epoxy resin is bisphenol S-based. In one embodiment, the epoxy resin is glycidylamine. In one embodiment, the epoxy resin is novolac. In one embodiment, the epoxy resin is aliphatic. In one embodiment, the epoxy resin is halogenated. 【0063】 Specific epoxy resins suitable for use in the present invention include the following: 【0064】 Bisphenol A derivatives: EPON 828, EPON 825, EPON 826, EPON 830, Epon 834 (Hexion), DER 332 (Dow Chemical), Tactix 123, and Tactix 138 (Huntsman). 【0065】 Bisphenol F derivatives: Araldite GY 281 / 282 / 285 (Huntsman) and Rutapox 0158 (Bakelite). 【0066】 Epoxyphenol novolac series: DEN 431, DEN 428, DEN 439 (Dow Chemical), EPN 1138 and EPN 1139 (Huntsman). 【0067】 Glycidylamine: Araldite MY 9512, Araldite MY 721, and Araldite MY 720 (Huntsman). 【0068】 Halogenation (bromination): Araldite LT 8049 (Huntsman, DER 542 (Dow Chemical)). 【0069】 Alicyclic epoxys: CY179-1 (Diacel), Araldite 175 (Huntsman), and Epalloy 5000 (Huntsman). 【0070】 Examples of compounds having epoxy and urethane groups include urethane-modified epoxy resins. Examples include EPU-78-13S, EPU-6, EPU-11, EPU-15, EPU16A, EPU-16N, EPU-17T-6, EPU-1348 and EPU-1395 (Adeka Corporation), and Hydran CF-025 (DIC Corporation). 【0071】 2. Amine 【0072】 The structure of the amine used to produce the salt of the present invention is given by the general formula: 【0073】 R n X m Q It can be described by, 【0074】 During the ceremony, 【0075】 Q is an amine-containing group having either multiple amines or a single amino group. In either case, it is important that at least one primary or secondary amine is present. Non-limiting examples include monoamines, polyamines, and polyamidoamines. Q may also be an epoxy-amine adduct. The amines contain either an R or X group, either independently or in combination. Generally, the above formula describes a class of amine-containing compounds used as curing agents for epoxy resins known in the art. 【0076】 X is a polyether group selected from the group consisting of poly(propylene oxide) (PPO) compounds and poly(ethylene oxide) (PEO) compounds, or mixtures thereof. In one embodiment, X contains PPO. In one embodiment, X contains PEO. In one embodiment, X is a blend of PPO and PEO. In one embodiment, each X contains 2 to 50 monomer units of propylene oxide and / or ethylene oxide. In one embodiment, each X comprises 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 monomer units of propylene oxide and / or ethylene oxide. In one embodiment, each X comprises at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 monomer units of propylene oxide and / or ethylene oxide. In one embodiment, each X contains up to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, or 49 monomer units of propylene oxide and / or ethylene oxide. 【0077】 m is an integer such that m ≥ 0. 【0078】 R is a linear or branched, saturated or unsaturated aryl group or alkyl group, or a combination thereof. In one embodiment, the aryl group is C6-C 14It is an aryl group. In one embodiment, the aryl group is selected from the group consisting of phenyl, benzyl, tolyl, xylyl, and naphthyl. 【0079】 In one embodiment, the alkyl group is C1-C 24 It is an alkyl group. In one embodiment, the alkyl group is C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 12 , C 12 , C 13 , C 14 , C 15 , C 16 , C 17 , C 18 , C 19 , C 20 , C 21 , C 22 , C 23 , or C 24 It is an alkyl group. In one embodiment, the alkyl group is at least C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 12 , C 12 , C 13 , C 14 , C 15 , C 16 , C 17 , C 18 , C 19 , C 20 , C 21 , C 22 , or C 23 It is an alkyl group. In one embodiment, the alkyl group can be up to C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 12 , C 12 , C 13 , C 14 , C 15 , C 16 , C 17 , C 18 , C 19 , C 20 , C 21 , C 22 , C 23 , or C 24 It is an alkyl group. 【0080】 R is C1~C 12 Alkyl alkyl groups, C1-C 12 Heteroalkyl groups, C6-C 14 Aryl group, and C6~C 14 They may be substituted with 1 to 5 substituents independently selected from the group consisting of heteroaryl groups. C1-C 12 Examples of heteroalkyl groups include C1-C 12 Alkyloxy group, C1-C 12 Alkylamino group and C1-C 12 Haloalkyl groups are an example. 【0081】 R may contain 1 to 10 heteroatoms and / or substituents in its main chain (i.e., alkyl or aryl). Heteroatoms are any atoms other than C or H. Non-restrictive examples of such heteroatoms include N, O, P, and S. R may also not contain heteroatoms. 【0082】 n is an integer and n ≥ 0. If n ≥ 2, each example in R does not have to be identical to the others. 【0083】 It is understood that if m is 0, X does not exist, and if n is 0, R does not exist. 【0084】 R n X m It can also be understood that Q is not a structural formula in that, even if X is present, at least one R group can directly bond to Q. 【0085】 3. Carboxylic acid 【0086】 The carboxylic acid used to prepare such carboxylic acid amine salts is not limited to any class and may be, for example, a substituted or unsubstituted monocarboxylic acid or polycarboxylic acid. Derivatives of polycarboxylic acids may also be used. 【0087】 In some embodiments, the carboxylic acid is a monocarboxylic acid. Examples of monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, caproic acid, etc., or hydroxycarboxylic acids such as glycolic acid and lactic acid. These monocarboxylic acids may be used individually or as a mixture of two or more of them. 【0088】 In one embodiment, the carboxylic acid is a dicarboxylic acid. In one embodiment, the dicarboxylic acid has the following formula. [ka] In the formula, R1 is either absent, saturated or unsaturated, linear or branched, aromatic, substituted or unsubstituted hydrocarbon group. Y1 and Y2 are independently a group containing nitrogen, oxygen, sulfur, or phosphorus, a C1-C6 alkyl group, an alkoxy group, and / or a phenyl group. X1 and X2 are independently hydrogen, a metal, a quaternary amine, an alcohol, or a hydrocarbon group having up to six carbon atoms, the hydrocarbon group being an alkyl group, an alkylene group, or an aromatic group, which may be branched or linear, and optionally having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus. 【0089】 Examples of metals X1 and X2 include alkali metals such as lithium, potassium, and sodium. 【0090】 As a guideline, some examples of possible embodiments of R1 are provided below, where R1 is selected from hydrocarbons having one or more of the following: 【0091】 Saturated, linear, or branched alkyl chains substituted with one or more groups containing nitrogen, oxygen, sulfur, or phosphorus (examples of such groups include carbonyl, ether, amide, amine, and alcohol); 【0092】 Unsaturated, branched, or linear alkyl groups; 【0093】 Unsaturated, branched, or linear alkyl groups substituted with one or more groups containing nitrogen, oxygen, sulfur, or phosphorus (examples of such groups include carbonyl, ether, amide, amine, and alcohol); 【0094】 One or more polyethylene glycol or polypropylene glycol groups; 【0095】 Aromatic groups optionally substituted with one or more alkyl groups, nitrogen-containing groups, oxygen-containing groups, sulfur-containing groups, or phosphorus-containing groups (examples of such groups include carbonyl, ether, amide, amine, and alcohol); and 【0096】 One or more of the following: alkenes, alkynes, alcohols, carbonyl groups, ethers, amines, amides, phenyl groups, benzene groups, furan groups, pyridine or pyran groups, or imidazole groups. 【0097】 In some embodiments, R1 may also include the exemplary hydrocarbon group combinations described above. It should also be recognized that in some embodiments, R1 may be optional. 【0098】 Examples of dicarboxylic acids that may be used in specific embodiments of the present invention include DL-tartaric acid, L-tartaric acid, D-tartaric acid, fumaric acid, mesaconic acid, oxamic acid, succinic acid, 2-methylsuccinic acid, L-malic acid, DL-malic acid, D-malic acid, aspartic acid, mesoxalic acid, muconic acid, oxaloacetic acid, glutamic acid, diglycolic acid, iminodiacetic acid, 2,2'-oxydipropanoic acid, 3,3'-oxydipropanoic acid, 2,2'-[1,2-ethanediylbis(oxy)]bisacetic acid, 3,3'-[1,2-ethanediylbis(oxy)]bispropanoic acid, and 3,3'-[oxybis(oxy)]bis-propanoic acid. This includes tan-2,1-diyloxy)dipropanoic acid, poly(ethylene glycol)bis-acetic acid, polyethylene glycol bis(carboxymethyl) ether, polyethylene glycol diacitate 600, keridonic acid, dipicolinic acid, 2,5-franzicarboxylic acid, isophthalic acid, terephthalic acid, orthophthalic acid, trimesic acid, 1,4-phenylenediacetic acid, 1,3-phenylenediacetic acid and their derivatives, such as ammonium dibasic tartrate, potassium monobasic tartrate, ammonium hydrogen oxalate, monomethyl fumarate, and monoethyl fumarate, as well as mixtures thereof. 【0099】 In some embodiments, the dicarboxylic acid may include one or more keto acids, such as hydroxypyruvic acid, alpha-ketoglutarate and beta-ketoglutarate, alpha-ketoadipic acid, α-ketovaleric acid, levulinic acid, 4-hydroxy-2-oxopentanoic acid, and 4-hydroxyphenylpyruvic acid. 【0100】 4. Surfactants 【0101】 The sizing composition may also contain a surfactant. The surfactant is not particularly limited and can be selected from nonionic, anionic, cationic, and amphoteric surfactants known to those skilled in the art. One or at least two of such emulsifiers may be used. 【0102】 Examples of nonionic surfactants include linear polyoxyalkylene alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene cetyl ether; branched polyoxyalkylene primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, and polyoxyethylene isostearyl ether; branched polyoxyalkylene secondary alkyl ethers such as polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-octylhexyl ether, polyoxyethylene 1-hexyloctyl ether, polyoxyethylene 1-pentylheptyl ether, and polyoxyethylene 1-heptylpentyl ether; polyoxyalkylene alkenyl ethers such as polyoxyethylene oleyl ether; and polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene dodecylphenyl ether. Polyoxyalkylene alkylphenyl ethers such as polyoxyethylene tripenzylphenyl, polyoxyethylene dibenzylphenyl ether, and polyoxyethylene benzylphenyl ether; polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene monomyristilate, polyoxyethylene dilaurate, polyoxyethylene dioleate, polyoxyethylene dimyristilate, and polyoxyethylene distearate; sorbitan esters such as sorbitan monopalmitate and sorbitan monooleate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; glycerin fatty acid esters such as glycerin monostearate, glycerin monolaurate, and glycerin monopalmitate; polyoxyalkylene sorbitol fatty acid esters; sucrose fatty acid esters;Examples include polyoxyalkylene castor oil ethers such as polyoxyethylene castor oil ether; polyoxyalkylene hydrogenated castor oil ethers such as polyoxyethylene hydrogenated castor oil ether; polyoxyalkylene alkylamino ethers such as polyoxyethylene laurylamino ether and polyoxyethylene stearylamino ether; oxyethylene-oxypropylene blocks or random copolymers; terminally alkyl etherified oxyethylene-oxypropylene blocks or random copolymers; and terminally sucrose-etherified oxyethylene-oxypropylene blocks or random copolymers. 【0103】 Among these nonionic surfactants, branched polyoxyalkylene primary alkyl ethers, branched polyoxyalkylene secondary alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, oxyethylene-oxypropylene block copolymers, and terminally alkyl etherified oxyethylene-oxypropylene block copolymers are preferred due to their excellent ability to emulsify silicone compounds in water. Furthermore, oxyethylene-oxypropylene block or random copolymers and terminally alkyl etherified oxyethylene-oxypropylene block copolymers are more preferred due to their ability to transform into a tar-like substance on the fibers during the firing process, which protects the fibers from damage. 【0104】 Anionic surfactants include salts of various acids such as fatty acid salts, hydroxyacetic acid, potassium hydroxyacetate, lactic acid, and potassium lactate; salts of polyoxyalkylene alkyl ether acetates such as sodium salt of polyoxyalkylene tridecyl ether acetate; salts of carboxyl-substituted aromatic compounds such as potassium trimellitate and potassium pyromellitate; salts of alkylbenzene sulfonic acids such as salt of dodecylbenzenesulfonic acid; salts of polyoxyalkylene alkyl ether sulfonic acids such as salt of polyoxyethylene 2-ethylhexyl ether sulfonic acid; salts of higher fatty acid amide sulfonic acids such as salt of stearoyl methyl taurine, salt of lauroyl methyl taurine, salt of myristoyl methyl taurine, and salt of palmitoyl methyl taurine; and N-acyl sarcosinic acid such as salt of lauroyl sarcosinic acid. This includes salts of phosphates; salts of alkylphosphonic acids such as salts of octylphosphonates; salts of aromatic phosphonic acids such as potassium salt of phenylphosphonate; salts of alkylphosphonic acids such as salt of 2-ethylhexylphosphonate mono-2-ethylhexyl ester; salts of nitrogen-containing alkylphosphonic acids such as salt of aminoethylphosphonic acid and its diethanolamine salt; salts of alkylsulfates such as salt of 2-ethylhexylsulfate; salts of polyoxyalkylene sulfates such as salt of polyoxyethylene 2-ethylhexyl ether sulfate; salts of long-chain sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate and sodium dioctyl sulfosuccinate; and long-chain N-acyl glutamates such as monosodium N-lauroyl glutamate and disodium N-stearoyl-L-glutamate. Anionic surfactants may also include alkyl phosphates and aryl phosphates and their derivatives. 【0105】 Examples of cationic surfactants include quaternary ammonium salts such as lauryltrimethylammonium chloride and oleylmethylethylammonium ethosulfate; and (polyoxyalkylene) alkylamino ether salts such as (polyoxyethylene)laurylaminoether lactate, stearylaminoether lactate, and (polyoxyethylene)laurylaminoethertrimethylphosphate. 【0106】 Examples of amphoteric emulsifiers include imidazoline amphoteric surfactants such as sodium 2-undecyl-N,N-(hydroxyethylcarboxymethyl)-2-imidazolinate and disodium 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyl oxyate; betaine amphoteric surfactants such as 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, lauryldimethylaminoacetic acid betaine, alkyl betaine, amide betaine and sulfobetaine; and amino acid amphoteric surfactants such as N-laurylglycine, N-lauryl-β-alanine and N-stearyl-β-alanine. 【0107】 5. Viscosity modifier 【0108】 In some embodiments, the sizing composition may contain one or more viscosity modifiers. Generally, the viscosity modifiers include any composition that adjusts the viscosity as desired without hindering the effects of the present invention. Viscosity modifiers may include natural polymers such as starch, cellulose, arginate, agar, carrageenan, collagen, gelatin, guar gum, and xanthan gum. Examples of cellulose polymers may include methylcellulose, hydroxypropylmethylcellulose, ethylcellulose, hydroxyethylcellulose, and carboxymethylcellulose. Viscosity modifiers may also include synthetic acrylic polymers such as alkali-swellable (or soluble) emulsions (ASE), hydrophobic-modified alkali-swellable emulsions (HASE), and hydrophobic-modified ethoxylated urethane resins (HEUR). In some embodiments, viscosity modifiers may include aminocarboxylic acid materials such as alkylamine carboxylates, arylamine carboxylates, alkylarylamine carboxylates, amino acids, and betaine compounds. 【0109】 6. Additional ingredients 【0110】 In addition to the above components, the sizing composition of the present invention may further contain components, provided that these components do not inhibit the effects of the present invention. These components may include antioxidants such as phenolic compounds, amines, sulfur, phosphorus, or quinone compounds; antistatic agents such as sulfates, sulfonates, or phosphates of higher alcohols or higher alcohol ethers; lubricants such as polyethylene glycol, polyvinyl alcohol, alkyl esters of higher alcohols, ethers of higher alcohols, and waxes; antimicrobial agents; preservatives; corrosion inhibitors; and hygroscopic agents. In some embodiments, the lubricant may include polyethylene glycol having an average molecular weight of 100 to 10,000. More preferably, the lubricant may include polyethylene glycol having an average molecular weight of 800 to 8,000. In preferred embodiments, the lubricant may include polyethylene glycol having an average molecular weight of 1,000 to 2,000. In one embodiment, polyethylene glycol is present in the composition in an amount of 1 to 40% by weight, relative to the total weight of solids in the sizing composition. 【0111】 In one embodiment, the carboxylate is present in the composition in an amount of about 0.01% to about 80% by weight, relative to the total weight of solids in the sizing composition. In one embodiment, the carboxylate is present in amounts of about 0.01% by weight, about 0.05% by weight, about 0.1% by weight, about 0.2% by weight, about 0.3% by weight, about 0.4% by weight, about 0.5% by weight, about 0.6% by weight, about 0.7% by weight, about 0.8% by weight, about 0.9% by weight, about 1% by weight, about 1.1% by weight, about 1.2% by weight, about 1.3% by weight, about 1.4% by weight, about 1.5% by weight, about 1.6% by weight, about 1.7% by weight, about 1.8% by weight, about 1.9% by weight, about 2% by weight, about 3% by weight, about 4% by weight, and about 5% by weight. %, about 6% by weight, about 7% by weight, about 8% by weight, about 9% by weight, about 10% by weight, about 11% by weight, about 12% by weight, about 13% by weight, about 14% by weight, about 15% by weight, about 16% by weight, about 17% by weight, about 18% by weight, about 19% by weight, about 20% by weight, Approximately 21% by weight, approximately 22% by weight, approximately 23% by weight, approximately 24% by weight, approximately 25% by weight, approximately 26% by weight, approximately 27% by weight, approximately 28% by weight, approximately 29% by weight, approximately 30% by weight, approximately 31% by weight, approximately 32% by weight, approximately 33% by weight, approximately 34% by weight, approximately 35% by weight %, about 36%, about 37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50 Weight%, about 51 weight%, about 52 weight%, about 53 weight%, about 54 weight%, about 55 weight%, about 56 weight%, about 57 weight%, about 58 weight%, about 59 weight%, about 50 weight%, about 51 weight%, about 52 weight%, about 53 weight%, about 54 weight%, about It is present in the composition in amounts of 55% by weight, approximately 56% by weight, approximately 57% by weight, approximately 58% by weight, approximately 59% by weight, approximately 60% by weight, approximately 61% by weight, approximately 62% by weight, approximately 63% by weight, approximately 64% by weight, approximately 65% ​​by weight, approximately 66% by weight, approximately 67% by weight, approximately 68% by weight, approximately 69% by weight, approximately 70% by weight, approximately 71% by weight, approximately 72% by weight, approximately 73% by weight, approximately 74% by weight, approximately 75% by weight, approximately 76% by weight, approximately 77% by weight, approximately 78% by weight, approximately 79% by weight, or less than, greater than, approximately 80% by weight, or in amounts of the above values. 【0112】 Consideration 【0113】 The aforementioned issues with the appearance (cosmetic) of fibers, such as “stripes” or other visual inconsistencies, are usually resolved by implementing engineering controls in manufacturing, such as improving control over the sizing content of the fibers and avoiding the inclusion of impurities. 【0114】 Amine-based curing agents are commonly used to cure epoxy resins. They are also added to epoxy sizing to improve the properties of carbon fiber-vinyl ester composites, as taught in U.S. Patent Application Publication No. 2013 / 0224470. These curing agents consist of polyamines containing primary and secondary amine groups. This reference does not teach the use of amine carboxylate salts as potential crosslinking agents for epoxy materials. Unsuppressed polyamines, whose use is taught in these documents, are unsuitable for conventional manufacturing due to their excessive reactivity to epoxy groups in sizing, causing serious complications such as gelation of the sizing emulsion in the sizing bath and accumulation on the drying roll surface due to the formation of a highly insoluble and sticky partially cured epoxy material over time, even at ambient temperatures. 【0115】 Japanese Patent Publication No. 2013-127132 teaches the use of tertiary amine salts to improve matrix adhesion to carbon fibers. However, in addition to the fact that the effect of adding these salts on the appearance of the fiber tow is not discussed, this Comparative Example 3 shows that tertiary amines are not effective in darkening the tow because they cannot participate in the crosslinking reaction with epoxy compounds. 【0116】 The inventors have found that the "darkness" of carbon fiber filaments generally depends on two parameters: the filament surface roughness in the unsized state and the sizing morphology / sizing distribution in the sized state. While it is very difficult to change and control the initial carbon fiber surface roughness in a way that can be repeatedly reproduced in the manufacturing setup, it is much easier to change and control the sizing morphology / sizing distribution. The inventors have also found that reducing the brightness / gloss of the sized tow to make it darker is highly desirable and advantageous in masking the aforementioned visual defects. Through diligent research, it has been discovered that the use of certain latent amine curing agents in epoxy-containing sizes can result in a much darker carbon fiber tow appearance when cured in sizes that solve the above problems. 【0117】 As shown below, certain structures of carboxylate salts of amine-containing curing agents have been found to be particularly effective in reducing the gloss / sheen of the fiber tow and darkening the appearance of the fiber tow when used in epoxy-containing carbon fiber sizes. 【0118】 From both Tables 1 and 2 and their examples, it can be seen that the darkness of the tow can be effectively increased by adding a latent amine-based curing agent to the epoxy sizing formulation, applying it to the fibers, and drying / curing it at a selected temperature. The final drying temperature may be selected to allow the epoxy-containing formulation to cure. The final drying temperature may also be selected to be higher than the curing peak temperature obtained by DSC experiments. The final drying temperature may also be selected to be 1–50°C higher than the curing peak temperature obtained by DSC experiments. The final drying temperature may also be selected to be 5–40°C higher than the curing peak temperature obtained by DSC experiments. 【0119】 A difference of 10 grayscale peak values ​​is usually discernible to the naked eye; therefore, a grayscale peak value of at least 125 is desirable, a grayscale peak value of 115 is more desirable, and a grayscale peak value of less than 105 is particularly desirable. As can be seen from the comparative examples, most of the unsuppressed (i.e., uncarboxylated) amine curing agents investigated worked in terms of darkening the fibers, but were too reactive to be used in the manufacturing settings (above), as can be seen when comparing the DSC start / peak curing temperatures of, for example, Comparative Example 5 (unsuppressed Aradur 3986) and Example 15 (suppressed Aradur 3986). The degree of latentness (curing wait time) of suppressed curing agents depends on both the properties of the curing agent (types of amine groups present) and the properties of the carboxylic acid used as the suppressor (particularly pKa and boiling point). The degree to which one wants to suppress (inhibit) an amine-containing curing agent depends on processing parameters such as the fiber drying temperature and the nature of drying (contact drying, non-contact drying) after sizing application. Comparative Example 2 was investigated as a type of non-inhibitory curing agent taught in U.S. Patent Application Publication No. 2013 / 0224470. As shown therein, this curing agent was completely ineffective in darkening the fibers. Comparative Example 3 was investigated as a type of tertiary amine additive described in Japanese Patent Publication No. 2013-127132. Since tertiary amines cannot participate in epoxy crosslinking reactions and only catalyze the chain extension / condensation reactions of epoxys, this type of curing agent did not affect the darkening of the tow. 【0120】 Amine compounds also preferably possess a degree of hydrophobicity, mainly due to the presence of the R group mentioned above. If only one R group is present and the R group is aliphatic, it is at least C 12 It is preferable that the R group (C 18 ) is otherwise a smaller C than an amine with the same structure. 12 It is effective in darkening the fibers compared to the base. Also, Aradur 340 is C 13 and Aradur 435 C 19 ~C 20It is presumed to have an R group in the system. Although not limiting to the present invention, Jeffamine M600 (Comparative Example 2) is thought to have no effect of darkening fibers because it does not have a hydrophobic group. However, the effectiveness of certain amines of this type that do not have an R group, such as Jeffamine M600 and O,O'-bis(3-aminopropyl)diethylene glycol (BADG), can be improved to some extent by neutralization with a carboxylic acid having a hydrophobic group, such as decanoic acid (Example 13). [Examples] 【0121】 example 【0122】 HexTow® AS4C-3K (Hexcel, Stamford, Connecticut) unsized carbon fiber tow with 3,000 filaments was used in these studies. Amine-containing curing agents ARADUR 340, ARADUR 435, and ARADUR 3986 were obtained from Huntsman (Salt Lake City, Utah). CARBOWAX® SENTRY® polyethylene glycol 1450 was obtained from Dow Chemical (Midland, Michigan). GP-sized emulsion was obtained from Hexcel. Toximul TA-8 (taloamine ethoxylate) was obtained from Stepan (Northfield, Illinois). All other materials were obtained from Sigma-Aldrich (St. Louis, Missouri). 【0123】 Preparation of control and stock emulsions 【0124】 For Control 1, a commercially available bisphenol A epoxy emulsion, "GP" (Hexcel), was used. For Control 2, Carbowax 1450 was mixed with the Control 1 emulsion at a concentration of 10% by weight relative to the epoxy, in order to function as a stock emulsion for curing studies. 【0125】 Preparation of inhibitory amine carboxylate salts 【0126】 The amine-containing curing agent was reacted with an excess carboxylic acid in aqueous solution at 60°C for 2 hours to completely neutralize it. Stoichiometry was calculated either from the known structure and molecular weight, or from the amine value of the curing agent reported by the supplier when the exact structure was unknown. The degree of neutralization was confirmed by pH measurement. These solutions of the latent curing agent were then added to a desired amount of diluted version (1 wt% in water) of the stock emulsion (described above). 【0127】 Sizing application, drying / curing 【0128】 All emulsions were applied to the tows from the sizing bath at a concentration of 1 wt% and dried at various temperatures by either non-contact drying (drying tower) or contact drying (steam drum, followed by drying tower). When simultaneous drying and curing were used, the drying temperature used was equal to or higher than the curing peak temperature determined by DSC (see below) so that the coated tows would also be cured. 【0129】 Determination of curing temperature 【0130】 All emulsions were dried under vacuum at ambient temperature, and small samples were subjected to DSC (Discovery, TA Instruments) in air at a heating rate of 5°C / min. The peak temperature of the exothermic curing reaction and the onset temperature of its transition were recorded. 【0131】 Method for evaluating the darkness of the tou 【0132】 A plate with double-sided tape attached to its surface was prepared. The toe was pulled tightly across the plate and pressed into the double-sided tape. The toe was imaged using a Keyence VHX-5000 with a VH-Z100R lens and OP-72402 ring light. Rotation of the plate around the vertical axis was used for measurements at different phi angles. The mosaic image was acquired in 3D image stitching mode with 100x lens magnification, full ring illumination, monochrome capture mode, manual shutter speed of 1.00 ms, and 0 dB gain. After image acquisition, the images were processed using an in-house scripted Matlab workflow. A 2.2 mm portion along the length and width of the toe constituted each measurement area. Nine areas were selected for each toe. Figure 2 shows an example of a toe with nine areas selected, which is provided to illustrate the analysis method and is not necessarily typical of fibers with data presented in Figure 1 or Table 3. Grayscale values ​​were recorded at numerous locations within each of the nine areas. For each region, either the median grayscale or peak grayscale value was recorded between 0 and 255. For peak grayscale measurements, a histogram of grayscale values ​​was calculated, smoothed, and the maximum value from the smoothed curve was reported. The average of nine values ​​from each region was reported (Table 1). For median grayscale measurements, the average value was calculated for the nine regions and reported as the median grayscale darkness average in Table 3 and Figure 1. The values ​​in Table 1 were measured at a 75-degree phi angle. 【0133】 Controls 1 and 2 【0134】 These emulsions did not contain a curing agent. They were applied to carbon fiber tows starting at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. 【0135】 Example 1 【0136】 The amide amine epoxy curing agent ARADUR 340 was inhibited by neutralization with acetic acid at an amine:acid stoichiometric ratio of 1:3. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.45. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 110°C. The average peak grayscale value of this tow was measured and reported in Table 1. 【0137】 Example 2 【0138】 The amide amine epoxy curing agent ARADUR 340 was inhibited by neutralization reaction with fumaric acid at an amine:acid stoichiometric ratio of 1:1.25. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.45. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 150°C. The mean peak grayscale values ​​of this tow were measured and reported in Table 1. 【0139】 Example 3 【0140】 The amide amine epoxy curing agent ARADUR 340 was inhibited by neutralization reaction with fumaric acid at an amine:acid stoichiometric ratio of 1:1.25. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.28. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 150°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0141】 Example 4 【0142】 The amide amine epoxy curing agent ARADUR 340 was inhibited by neutralization reaction with lactic acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0143】 Example 5 【0144】 The curing agent ARADUR 340, an amide amine epoxy, was inhibited by neutralization with acetic acid at a stoichiometric amine:acid ratio of 1:3. A solution of this curing agent was added to control emulsion 2 to obtain a stoichiometric epoxy:amine salt ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 105°C. The mean peak grayscale of this tow was measured and reported in Table 1. 【0145】 Example 6 【0146】 The amide-amine epoxy curing agent ARADUR 340 was inhibited by neutralization reaction with iminodiacetic acid at an amine:acid stoichiometric ratio of 1:1.25. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.45. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by contact drying at 110°C (steam drum), followed by non-contact curing at 155°C (drying tower). The mean peak grayscale values ​​of the tow were measured and reported in Table 1. 【0147】 Example 7 【0148】 Dodecylamine was inhibited by neutralization with iminodiacetic acid at an amine:acid stoichiometric ratio of 1:1.25. A solution of this curing agent was added to the control emulsion to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by contact drying at 110°C (steam drum), followed by non-contact curing at 155°C (drying tower). The mean peak grayscale of this tow was measured and reported in Table 1. 【0149】 Example 8 【0150】 Octadecylamine was inhibited by neutralization with acetic acid in an amine:acid stoichiometric ratio of 1:2. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 135°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0151】 Example 9 【0152】 Dodecylamine was inhibited by neutralization with acetic acid in an amine:acid stoichiometric ratio of 1:2. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 135°C. The mean peak grayscale of this tow was measured and reported in Table 1. 【0153】 Example 10 【0154】 The amide amine epoxy curing agent ARADUR 435 was inhibited by neutralization reaction with fumaric acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 160°C. The mean peak grayscale of this tow was measured and reported in Table 1. 【0155】 Example 11 【0156】 The amide amine epoxy curing agent ARADUR 435 was inhibited by neutralization reaction with fumaric acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.18. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 160°C. The mean peak grayscale of this tow was measured and reported in Table 1. 【0157】 Example 12 【0158】 The amide amine epoxy curing agent ARADUR 435 was inhibited by neutralization reaction with monoethyl fumarate at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 160°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0159】 Example 13 【0160】 O,O'-bis(3-aminopropyl)diethylene glycol (BADG) was inhibited by neutralization reaction with decanoic acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to the emulsion of control 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0161】 Example 14 【0162】 The epoxy-amine adduct curing agent ARADUR 3986 was inhibited by neutralization reaction with iminodiacetic acid at an amine:acid stoichiometric ratio of 1:1.2. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 170°C. The mean peak grayscale values ​​of this tow were measured and reported in Table 1. 【0163】 Example 15 【0164】 The epoxy-amine adduct curing agent ARADUR 3986 was inhibited by neutralization reaction with oxamic acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 180°C. The mean peak grayscale of this tow was measured and reported in Table 1. 【0165】 Example 16 【0166】 Octadecylamine was inhibited by neutralization with glycolic acid ethoxylate 4-nonylphenyl ether at an amine:acid stoichiometric ratio of 1:1.5. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0167】 Example 17 【0168】 The curing agent of Example 15 was used. A solution of this curing agent was added to the emulsion of Control 2 to obtain a stoichiometric ratio of epoxy:amine salt of 1:0.52. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by contact drying at 125°C (steam drum), followed by non-contact curing at 175°C (drying tower). The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0169】 Example 18 【0170】 The fibers from Example 3 were woven into a simple 196gsm fabric. Twenty-one tows from the filling direction were analyzed for darkness, and the average peak grayscale values ​​are reported in Table 2. 【0171】 Example 19 【0172】 The amide amine epoxy curing agent ARADUR 340 was inhibited by neutralization with fumaric acid at an amine:acid stoichiometric ratio of 1:2. A solution of this curing agent was added to control emulsion 2 to obtain an epoxy:amine salt stoichiometric ratio of 1:0.36. The resulting emulsion was applied to carbon fiber tows starting at 1 wt% concentration and dried by non-contact drying (drying tower) at 150°C. These fibers were woven into a simple 196 gsm fabric. Twenty-one tows from the packing direction were analyzed for darkness, and the mean values ​​of the peak grayscale are reported in Table 2. 【0173】 Example 20 【0174】 The epoxy-amine adduct curing agent ARADUR 3986 was inhibited by neutralization reaction with acetic acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain a stoichiometric ratio of epoxy:amine salt of 1:1.5. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0175】 Example 21 【0176】 The same sizing formulation as in Example 20 was used, but the sized fibers were dried by non-contact drying (drying tower) at 160°C. The average value of the peak grayscale of this tow was measured and reported in Table 1. 【0177】 Example 22 【0178】 The epoxy-amine adduct curing agent ARADUR 3986 was inhibited by neutralization reaction with acetic acid at an amine:acid stoichiometric ratio of 1:1.1. A solution of this curing agent was added to control emulsion 2 to obtain a stoichiometric ratio of epoxy:amine salt of 1:2. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0179】 Example 23 【0180】 The same sizing formulation as in Example 22 was used, but the sized fibers were dried by non-contact drying (drying tower) at 160°C. The average value of the peak grayscale of this tow was measured and reported in Table 1. 【0181】 Comparative Example 1 【0182】 The unsuppressed amide amine epoxy curing agent ARADUR 340 was dissolved in control emulsion 2 to obtain an epoxy:amine stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0183】 Comparative Example 2 【0184】 The unsuppressed amine epoxy curing agent Jeffamine M-600 was dissolved in control emulsion 2 to obtain an epoxy:amine stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0185】 Comparative Example 3 【0186】 The unsuppressed tertiary amine emulsifier Toximul TA-8 was dissolved in control emulsion 2 to obtain an epoxy:amine stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 160°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0187】 Comparative Example 4 【0188】 The unsuppressed amide amine epoxy curing agent ARADUR 435 was dissolved in control emulsion 2 to obtain an epoxy:amine stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0189】 Comparative Example 5 【0190】 The unsuppressed amine-epoxy condensate curing agent ARADUR 3986 was dissolved in control emulsion 2 to obtain an epoxy:amine stoichiometric ratio of 1:0.36. The resulting emulsion was applied to a carbon fiber tow at a concentration of 1 wt% and dried by non-contact drying (drying tower) at 125°C. The mean value of the peak grayscale of this tow was measured and reported in Table 1. 【0191】 Comparative Example 6 【0192】 Carbon fibers sized to "GP" (control 1) as shown in Table 1 were woven into a simple 196gsm fabric. Twenty-one tows from the filling direction were analyzed for darkness, and the average peak grayscale values ​​are reported in Table 2. 【0193】 [Table 1-1] [Table 1-2] 【0194】 [Table 2] 【0195】 Further experiments were conducted to evaluate the variation in darkness of the fibers at different observation angles (phi angles) for the control and specific darker experimental fibers. As described above, nine different regions were selected for each fiber, and grayscale values ​​were recorded at multiple points within each of the nine regions. A median grayscale value was determined for each of the nine regions. For each fiber, the average of the nine median grayscale values ​​was calculated at each observation angle. The data are shown in Table 3, and the results are shown in Figure 1. It was found that all of the darker experimental fibers showed less variation in darkness than the control. 【0196】 [Table 3] 【0197】 Those skilled in the art who benefit from the teachings presented in the above description and the accompanying drawings will likely recognize many modifications and other embodiments of the invention described herein. It will be understood that the invention is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. 【0198】 Certain terms are used herein, but they are used only in a general and descriptive sense and not for limiting purposes. Each embodiment disclosed herein is considered applicable to each of the other disclosed embodiments. All combinations and partial combinations of the various elements described herein are within the scope of the embodiments.

Claims

[Claim 1] a. Epoxy-containing resin and b. Amine carboxylates and A sizing composition comprising, The aforementioned amine, R ｎ X ｍ Q It has, During the ceremony, Q is an amine-containing group comprising at least one primary or secondary amine, X is a polyether group selected from the group consisting of poly(propylene oxide) (PPO) compounds, poly(ethylene oxide) (PEO) compounds, or mixtures thereof. m is an integer, and m ≥ 0, R is an aryl or alkyl group, each alkyl group may independently be linear or branched, each alkyl group may independently be saturated or unsaturated, R contains 0 to 10 heteroatoms, and R is unsubstituted or C １ -C １２ alkyl group, C １ -C １２ heteroalkyl group, C ６ -C １４ aryl group and C ６ -C １４ is either substituted with 1 to 5 substituents selected from the group consisting of heteroaryl groups, A sizing composition in which n is an integer and n ≥ 0. [Claim 2] The composition according to claim 1, wherein Q is a monoamine. [Claim 3] The composition according to claim 1, wherein Q comprises multiple amino groups. [Claim 4] The composition according to claim 3, wherein Q comprises a plurality of primary or secondary amino groups. [Claim 5] The composition according to claim 1, wherein Q contains a polyamidoamine. [Claim 6] The composition according to claim 1, wherein Q comprises an epoxy-amine adduct. [Claim 7] The composition according to any one of claims 1 to 6, wherein X contains PPO. [Claim 8] The composition according to any one of claims 1 to 6, wherein X contains PEO. [Claim 9] The composition according to any one of claims 1 to 6, wherein m ≥ 1, m ≥ 2, or m ≥ 3. [Claim 10] A composition according to any one of claims 1 to 5, wherein X is not present. [Claim 11] The composition according to any one of claims 1 to 6, wherein at least one R is a linear chain. [Claim 12] The composition according to any one of claims 1 to 6, wherein at least one R is branched. [Claim 13] The composition according to any one of claims 1 to 6, wherein at least one R is saturated. [Claim 14] The composition according to any one of claims 1 to 6, wherein at least one R is unsaturated. [Claim 15] The composition according to any one of claims 1 to 6, wherein R is unsubstituted. [Claim 16] The composition according to any one of claims 1 to 6, wherein R is substituted. [Claim 17] The composition according to any one of claims 1 to 6, wherein n ≥ 2 or n ≥ 3. [Claim 18] The composition according to any one of claims 1 to 6, wherein the carboxylate salt is derived from a monocarboxylic acid. [Claim 19] The composition according to any one of claims 1 to 6, wherein the carboxylate salt is derived from a polycarboxylic acid. [Claim 20] The composition according to any one of claims 1 to 6, wherein the carboxylate salt is derived from a polycarboxylic acid derivative having at least one free / unmodified acid group. [Claim 21] The composition according to any one of claims 1 to 6, wherein the molar ratio of epoxy to amine is 10:1 to 1:

10. [Claim 22] A carbon fiber prepared by drying and curing the composition according to any one of claims 1 to 6 on its surface. [Claim 23] A carbon fiber reinforced composite material comprising the carbon fiber described in claim 22. [Claim 24] A carbon fiber reinforced composite material according to claim 23, comprising a resin matrix injected into the fibers. [Claim 25] A method for preparing processed carbon fibers, To form processed carbon fibers, i) The step of applying the composition according to any one of claims 1 to 6 to carbon fibers to form coated carbon fibers, ii) A step of drying the coated carbon fiber, iii) A step of curing the coated carbon fiber Methods that include... [Claim 26] The method according to claim 25, wherein step i) is performed for 5 to 60 seconds. [Claim 27] The method according to claim 25, wherein step ii) is carried out at a temperature of 100°C to 190°C. [Claim 28] The method according to claim 25, wherein step ii) is performed for 15 seconds to 5 minutes. [Claim 29] The method according to claim 25, wherein step iii) is carried out at a temperature of 100°C to 190°C. [Claim 30] The method according to claim 25, wherein step iii) is performed for 15 seconds to 5 minutes. [Claim 31] The method of claim 25, wherein step ii) and step iii) are performed simultaneously. [Claim 32] The method according to claim 25, wherein step ii) and step iii) are carried out in succession.