Textile dyeing and processing methods

Abstract

To improve the dyeability of a high-strength fiber structure.SOLUTION: A high-strength fiber is subjected to plasma treatment. Then, a specific phenol is subjected to a condensation reaction with formaldehyde to make a dye binder, which is used to heat the high-strength fiber.SELECTED DRAWING: None

Description

Technical Field

[0001] This invention relates to a method for mainly improving the dyeing property of so-called high-strength fibers such as wholly aromatic polyamide fibers represented by Kevlar (registered trademark) and ultra-high molecular weight polyethylene fibers represented by Izanas (registered trademark).

Background Art

[0002] High-strength fibers such as ultra-high molecular weight polyethylene fibers, wholly aromatic polyamide fibers, polyketone fibers, poly(paraphenylene benzobisoxazole) fibers, and wholly aromatic polyester fibers have a highly crystalline and dense surface structure with strong intermolecular cohesive forces, making it inherently difficult to color them with conventional dyeing techniques. Therefore, various methods for dyeing have been proposed.

[0003] For example, a method of dyeing at high temperature and high pressure using a large amount of carriers such as acetophenone and para-phenylphenol (Patent Document 1), a method of pretreating with solvents such as tetramethylene sulfone and dimethyl sulfone and then dyeing (Patent Document 2), a method of padding and dyeing in a solvent such as N-methylpyrrolidone (Patent Document 3), a method of obtaining a colored yarn by dispersing a dye or pigment in a spinning solution of concentrated sulfuric acid and performing spinning (Patent Documents 4 and 5), a method of obtaining poly(paraphenylene terephthalamide) (PPTA) fibers that can be dyed with cationic dyes by contacting a dyeing accelerator after pre-dipping in a sulfuric acid solution (Patent Document 6), a method of dyeing aramid fibers at a temperature of 160°C or higher (Patent Document 7), and the like.

[0004] However, each of the above methods has problems such as environmental pollution caused by carriers or organic solvents and a decrease in fiber strength, and has not reached commercialization.

[0005] As an alternative to the methods described above, methods that have been considered include dyeing after plasma treatment of the fiber surface, and methods such as sputtering treatment of the fiber surface to form subtle irregularities on the fiber surface (Patent Document 8), and dyeing with a reactive dye having a special reactive group after low-temperature plasma treatment in the presence of ammonia or a lower alkylamine (Patent Document 9). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 58-87376 [Patent Document 2] Japanese Patent Application Publication No. 52-25178 [Patent Document 3] Japanese Patent Application Publication No. 62-268877 [Patent Document 4] Japanese Patent Application Publication No. 63-256765 [Patent Document 5] Japanese Patent Application Publication No. 2-41414 [Patent Document 6] Japanese Patent Application Publication No. 3-76868 [Patent Document 7] Japanese Patent Application Publication No. 5-209372 [Patent Document 8] Japanese Patent Application Publication No. 7-216729 [Patent Document 9] Japanese Patent Publication No. 62-223384 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, even in the method of dyeing after plasma treatment of the fiber surface, there are still challenges that need to be addressed.

[0008] For example, in the dyeing method disclosed in Patent Document 8, sputtering is a type of vacuum discharge treatment in which cations in an argon plasma are accelerated by a DC high electric field and collide with the solid surface of the cathode (target), knocking out atoms and molecules from the target and generating the desired thin film on the substrate on the anode side. However, the vacuum level in sputtering is preferably 10 to 10E-3 Torr, and processing fibers under such a vacuum level requires large-scale vacuum equipment and vacuum operating devices, resulting in significant capital investment and making commercialization difficult.

[0009] Furthermore, the dyeing method disclosed in Patent Document 9 can only use reactive dyes, making it difficult to achieve a wide range of deep hues.

[0010] In view of the background of the prior art, this invention proposes a technology for dyeing high-strength fiber structures that can be colored in dark hues. [Means for solving the problem]

[0011] In order to achieve the aforementioned objectives, the inventors investigated dyeing methods that offer excellent dyeability for high-strength fibers. They discovered that fibers obtained by oxygen plasma treatment, followed by heat treatment with a dye fixative and dyeing with a cationic dye, could unexpectedly solve the aforementioned problems all at once, leading to the completion of the present invention.

[0012] The present invention relates to a method for dyeing fibers, comprising a dyeing step of dyeing at least one fiber selected from ultra-high molecular weight polyethylene fiber, fully aromatic polyamide fiber, polyketone fiber, poly(p-phenylene benzbisoxazole) fiber, and fully aromatic polyester fiber using a dyeing agent, and before the dyeing step, the fiber Using oxygen plasma The method is characterized by comprising a plasma treatment step, and a dye fixing step, which is performed after the plasma treatment step, in which a dye fixing agent is used for heat treatment. The dye fixative is prepared by blending 40 mol% or more and less than 100 mol% of dihydroxydiphenyl sulfone and 60 mol% or less of phenolsulfonic acid to form phenols. To 1 mol of these phenols, 0.95 mol ratio or more of formaldehyde is added, and the total amount of alkali equivalent to the neutralization equivalent of free sulfuric acid present in the reaction system, the neutralization equivalent of sulfonic acid groups bonded to the phenols, and 0.1 to 1.3 equivalents of dihydroxydiphenyl sulfone is used as the alkali compounding amount. The dye fixative is obtained by subjecting the phenols and the aldehyde to a condensation reaction in the presence of an alkali.

[0013] The dye is characterized in that it is a cationic dye.

[0014] In the dye fixing step, the dye fixative is added in an amount of 1 to 10% by weight based on the weight of the fiber, and the treatment is carried out at a temperature of 60 to 140°C for 10 to 60 minutes in a bath with a bath ratio of 1:50.

[0015] In the plasma step is, The irradiation time is 10 seconds to 30 seconds.

[0016] At least one fiber selected from the group consisting of the ultra-high molecular weight polyethylene fiber, wholly aromatic polyamide fiber, polyketone fiber, polyparaphenylene benzobisoxazole fiber, and wholly aromatic polyester fiber is a wholly aromatic polyamide fiber or an ultra-high molecular weight polyethylene fiber.

Advantages of the Invention

[0017] By the fiber dyeing and finishing method of the present invention, it is possible to color a fiber material, which was difficult to achieve with conventional dyeing methods, with a deep hue without the need for large-scale vacuum equipment or vacuum operating devices.

Brief Description of the Drawings

[0018] [Figure 1] An example of a measurement plate used in the evaluation of washing fastness [[ID=三十四]] [Modes for carrying out the invention]

[0019] The dyeing method for high-strength fibers in this embodiment will be described below. The high-strength fibers with excellent dyeability in this embodiment may be in the form of fibers, or they may be fibrous structures (woven fabrics, knitted fabrics, nonwoven fabrics, etc.). The high-strength fibers are selected from ultra-high molecular weight polyethylene fibers, fully aromatic polyamide fibers, polyketone fibers, poly(p-phenylenebenzbisoxazole) fibers, and fully aromatic polyester fibers, with fully aromatic polyamide fibers also known as aramid fibers. These high-strength fibers, including aramid fibers, may be dyed directly, or the high-strength fibers may be used to dye fibrous structures. Examples of fibrous structures include woven fabrics, knitted fabrics, knitted materials, honeycomb-like materials, and nonwoven fabrics.

[0020] In the dyeing method of this embodiment, plasma treatment is performed before the dyeing process to improve the dyeability of the fiber surface. Plasma treatment is preferably performed at normal pressure or near atmospheric pressure. Performing the treatment at near atmospheric pressure has the advantage of eliminating the need for large-scale equipment and complicated operations such as vacuum equipment and vacuum operations. The above-mentioned normal pressure or near atmospheric pressure is 1.333 × 10⁻⁶ 4 ~10.664 × 10 4 It means Pa, and discharge is possible with a simple device that allows for easy pressure adjustment.

[0021] Any discharge treatment method can be used for plasma treatment. Examples include a direct method in which the fibers to be plasma treated are placed in the discharge space and then plasma treated, and a remote method in which the fibers to be plasma treated are placed outside the discharge space and plasma is blown onto the fibers from the discharge space.

[0022] The atmosphere (processing gas) used during plasma treatment is not particularly limited as long as it is a gas that generates plasma when an electric field is applied. Examples include air, nitrogen, oxygen, argon, helium, carbon dioxide, carbon monoxide, tetrafluorocarbon and other inert gases, and alcohols. These may be used individually or in mixtures of two or more. Oxygen is preferred as the processing gas because it allows for high-power plasma treatment, is safe, and is inexpensive. In addition, it can form functional groups, such as hydroxyl groups and carboxyl groups, that can react with specific dye fixatives on the fiber surface.

[0023] Furthermore, atmospheric pressure is preferred when performing plasma treatment. Since it is preferable that the fibers or fiber structures undergoing plasma treatment be kept at a uniform width to ensure uniform treatment, a known method is preferred in which the fibers or fiber structures are fed from a reel (feed-out reel) on which they are wound, and then plasma-treated while being wound onto a winding reel having approximately the same winding width as the original reel. Plasma treatment allows for the imparting of various functional groups to the surface of the treated substrate without significantly roughening the surface. For example, after oxygen plasma treatment, the oxygen content increases compared to before treatment. Peak separation suggests that functional groups such as -OH and -COOH are formed on these surfaces. The formation of these functional groups is thought to improve the adhesion between the fiber surface and the dye fixative, as will be discussed later.

[0024] As for the dye, we will use a cationic dye, which is a basic dye for acrylic fibers.

[0025] Next, regarding the dye fixative, while commonly used natural tannins and synthetic tannins can be used as dye fixatives, in this embodiment, a dye fixative obtained by condensing specific phenols with formaldehyde is used. Specifically, a commercially available dye fixative (product name Bisphenol-S / Phenolsulfonic acid resin) is used. This dye fixative is obtained by combining 40 mol% or more and less than 100 mol% of dihydroxydiphenylsulfone and 60 mol% or less of phenolsulfonic acid to form phenols, adding 0.95 mol or more of formaldehyde per mole of phenols, and condensing the phenols and aldehyde in the presence of an alkali whose alkali content is the sum of the neutralization equivalents for the free sulfuric acid present in the reaction system, the neutralization equivalents for the sulfonic acid groups attached to the phenols, and 0.1 to 1.3 equivalents for the dihydroxydiphenylsulfone.

[0026] In this embodiment, the fibers immediately after plasma treatment are treated in a bath with a dye fixative in an amount of 1 to 10% by weight relative to the weight of the fibers, at a temperature of 60 to 140°C for 10 to 60 minutes, with a bath ratio of 1:50. This allows the dye fixative to be fixed to the surface of the fibers.

[0027] Alternatively, the dye fixative may be added to the dye bath at the same time as the dye, and the above-mentioned amount of fixative, bath ratio, temperature, and time may be used. Furthermore, the dye fixative may be added after dyeing, and the dye bath may be treated at a temperature of 60-140°C for 10-60 minutes.

[0028] The following describes the verification and evaluation of the dyeability of fibers dyed using the method described above.

[0029] Furthermore, the verification and evaluation of improved dyeability of the following fibers were conducted using Kevlar®, a fully aromatic polyamide fiber, and Izanas®, an ultra-high molecular weight polyethylene fiber, with the above-mentioned dye fixative added at an appropriate amount of 5% by weight, and the oxygen plasma irradiation time was varied.

[0030] <Staining method> Fibers were prepared by irradiating Kevlar® and Izanas® with oxygen plasma for 0 seconds (irradiation time), and by irradiating them with oxygen plasma for 10, 20, 30, 40, 50, 60, 90, and 180 seconds. These fibers were then treated in a bath with a bath ratio of 1:50 at 130°C for 30 minutes with 5% by weight of the dye fixative Bisphenol-S / Phenolsulfonic acid resin added relative to the weight of the fiber. After that, the fibers were dyed with a cationic dye in a separate bath, followed by rinsing and drying.

[0031] <Evaluation Method> A measurement plate as shown in Figure 1 was created, and a photograph was taken using a camera (CANON EOS30D) with the white balance set to manual. During this process, the white color of a color checker (X-RITE COLOR CHECKER PASSPORT) was included in the photograph along with the measurement plate. After shooting, the white balance was adjusted using Photoshop (registered trademark 22.43 release 2021 version). The threads in the perforated areas of the plastic plate were enclosed in a frame (0.5cm x 1cm) and the blurring was averaged. Using the physical data L, A*, B* of the resulting color, the ΔE (formula difference) with a sample that had not been plasma-irradiated was calculated.

[0032] <Evaluation and Verification> [Table 1]

[0033] As shown in the evaluation results in Table 1, for Kevlar® and Izanas®, it was verified that the dyeability of fibers dyed with cationic dyes and fixed with Bisphenol-S / Phenolsulfonic acid resin as a dye fixative is improved by applying plasma irradiation before dyeing. In this case, it was found that with Kevlar®, the ΔE (equation difference) increased with longer oxygen plasma irradiation times, while with Izanas®, stable and good results could be obtained by irradiating with oxygen plasma for 40 to 60 seconds.

[0034] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made as long as they do not impair the features of the present invention.

[0035] For example, the dyeing method of the present invention can be applied to other fibers selected from ultra-high molecular weight polyethylene fibers, fully aromatic polyamide fibers, polyketone fibers, poly(p-phenylenebenzbisoxazole) fibers, and fully aromatic polyester fibers, and can improve dyeability.

[0036] Furthermore, as mentioned above, if the plasma process is performed before the dyeing process, the dye fixing process can be performed simultaneously with the dyeing process or as a separate process after the dyeing process. [Industrial applicability]

[0037] The fibers obtained by the fiber dyeing method of the present invention can be used not only for fabric products such as woven fabrics, knitted fabrics, and cloths, but also for things like fishing lines and strings, and are particularly suitable for fishing lines used in situations where contact with water is essential. [Explanation of Symbols]

[0038] 1. Measuring plate 2 holes 3. Fibers (threads)

Claims

1. A dyeing process in which at least one fiber or fiber structure selected from ultra-high molecular weight polyethylene fiber, fully aromatic polyamide fiber, polyketone fiber, poly(p-phenylenebenzbisoxazole) fiber, and fully aromatic polyester fiber is dyed using a dyeing agent, A plasma process in which the fibers are plasma-treated using oxygen plasma before the dyeing process, A dye fixing step is performed after the plasma step, in which a heat treatment is performed using the following dye fixing agent, A method for dyeing and processing fibers, characterized by having [a certain characteristic]. The aforementioned dye fixative is a dye fixative obtained by condensing the phenols by combining 40 mol% or more and less than 100 mol% of dihydroxydiphenyl sulfone and 60 mol% or less of phenolsulfonic acid, adding 0.95 mol or more of formaldehyde per mole of the phenols, and reacting the phenols and the aldehyde in the presence of an alkali whose alkali content is the sum of the equivalent amount of alkali to neutralize the free sulfuric acid present in the reaction system, the equivalent amount of alkali to neutralize the sulfonic acid groups attached to the phenols, and 0.1 to 1.3 equivalents of alkali to dihydroxydiphenyl sulfone.

2. The method for dyeing fibers according to claim 1, characterized in that the dyeing agent is a cationic dye.

3. The method for dyeing fibers according to claim 1 or 2, characterized in that the dye fixing step involves adding the dye fixative in an amount of 1 to 10% by weight relative to the weight of the fibers, and treating them in a bath with a bath ratio of 1:50 at a temperature of 60 to 140°C for 10 to 60 minutes.

4. The method for dyeing fibers according to any one of claims 1 to 3, characterized in that the irradiation time in the plasma step is 10 to 30 seconds.

5. The method for dyeing fibers according to any one of claims 1 to 4, characterized in that at least one fiber selected from the ultra-high molecular weight polyethylene fiber, all-aromatic polyamide fiber, polyketone fiber, poly(p-phenylenebenzbisoxazole) fiber, and all-aromatic polyester fiber is an all-aromatic polyamide fiber or an ultra-high molecular weight polyethylene fiber.

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