EP4722444A1

EP4722444A1 - Dyeing method for cellulosic fiber product

Info

Publication number: EP4722444A1
Application number: EP24815467.6A
Authority: EP
Inventors: Takuya NOAKI
Original assignee: Asahi Kasei Corp; Asahi Chemical Industry Co Ltd
Current assignee: Asahi Kasei Corp; Asahi Chemical Industry Co Ltd
Priority date: 2023-05-31
Filing date: 2024-05-28
Publication date: 2026-04-08
Also published as: CN121127645A; TWI901159B; JP2025116238A; WO2024247984A1; TW202507124A; JP7693958B2; JPWO2024247984A1

Abstract

Provided is a novel dyeing method with which it is possible to obtain cellulose fiber products dyed with a reactive dye that have high color fastness and do not undergo hydrolysis due to an alkali treatment while reducing CO₂ emissions by using an alkaline washing under specific temperature and pH conditions. The present invention relates to a dyeing method for cellulose fibers or a fiber product containing cellulose fibers, the dyeing method being batch type or continuous type and including: a dyeing reaction step in which cellulose fibers or a fiber product containing cellulose fibers are reacted with a reactive dye in a dyeing liquid; an alkaline washing step in which all or part of the dyeing liquid is discharged, and then the dyed fibers or fiber product are washed with an alkaline washing liquid having a pH of 10 to 14 and a temperature of 15 to 70°C; and a post-alkaline washing step of discharging the alkaline washing liquid and then washing with water.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to a dyeing method for cellulose fibers or a fiber product comprising cellulose fibers using a reactive dye. More particularly, the present invention relates to a dyeing method for cellulose fibers or a fiber product comprising cellulose fibers using a reactive dye, which comprises a specific washing step after a dyeing reaction step.

2. Description of the Related Art

In industrial dyeing of cellulose fibers or fiber products comprising cellulose fibers, when a reactive dye is used, an inorganic salt and an alkaline agent are added as dyeing auxiliaries together with the reactive dye into the dyeing bath, and dyeing with the reactive dye is carried out. The presence of an inorganic salt is necessary to promote the absorption of the dye into the cellulose fibers, while an alkaline agent is necessary to fix the reactive dye to the cellulose fibers. It is generally known that the introduction of an inorganic salt and an alkaline agent into the dyeing bath is an important factor for obtaining uniform dyed products. In dyeing using such a reactive dye, after the dyeing reaction is complete, unreacted dye and the inorganic salt and alkaline agent as dyeing auxiliaries must be washed away. The reasons for this are as follows:

·If unreacted dye remains, there is a risk of color fading and dye contamination of other fabrics, i.e., poor color fastness.
·Since the inorganic salt serves to exhaust the dye, if the salt concentration remains high, the dye itself cannot be removed.
·Since alkali is a skin irritant, it is necessary to reduce the pH of the fabric and neutralize it using an acid.

Thus, in the washing in conventional dyeing methods using a reactive dye, washing must be performed several times in order to prevent these chemicals from remaining on the dyed fabric.
In conventional water washing, washing at a high temperature (generally around 90°C, and at least 75°C or higher) has been performed in order to discharge the dye to a high degree.
Under these circumstances, it is common to use steam heated in a boiler to heat a large amount of washing water to a high temperature, which consumes a lot of energy, and a significant amount of time to raise the temperature and electricity is needed during operation, resulting in a large amount of CO₂ emissions.
Patent Literature 1 below proposes a washing method using an alkaline soaping bath for colored fiber materials with a reactive dye having a sulfate ethyl sulfonyl group, wherein washing is performed with a washing liquid at a temperature of 75 to 95°C and a pH of 9 to 10 for batch type washing and a pH of 9 to 12 for continuous washing.
Patent Literature 2 below describes dyeing cotton and cotton blend woven fabrics using a reactive dye, wherein washing is performed with a washing liquid containing 0.25 to 1 g/L of an alkaline liquid of 45 wt% KOH: 10-74 wt% and 50 Baume degree sodium silicate: 10-60 wt% at 200°F (93.3°C). In this case, the pH of the washing liquid is estimated to be approximately 11.
Patent Literature 3 below proposes a soaping agent suitable for washing at 70 to 75°C that has the equivalent effect to soaping performed at 90°C, and a treatment method that involves washing with a washing liquid which has a pH of 10 to less than 12 and which contains a soaping agent containing a water-soluble salt of a polymeric fatty acid at 70 to 75°C.
Patent Literature 4 below proposes a treatment method for dyed products dyed with a disperse dye and a reactive dye, preferably a nucleophilic substitution type reactive dye, that are easily decomposed by alkali treatment, the treatment method performed at a pH of 8 or higher, and preferably a pH to 10.0 to 13.5, and a temperature of 50 to 85°C, and preferably 60 to 80°C.

[Citations List]

[Patent Literature]

[PTL 1] Japanese Unexamined Patent Publication (Kokai) No. 62-78287
[PTL 2] U.S. Patent No. 5378242
[PTL 3] Japanese Unexamined Patent Publication (Kokai) No. 1-272888
[PTL 4] Japanese Unexamined Patent Publication (Kokai) No. 50-135383

[Non-Patent Literature]

[NPL 1] Reference Material 2, List of Calculation Formulas and Emission Factors for Calculating Greenhouse Gas Emissions (https://www.env.go.jp/earth/ondanka/suishin_g/3rd_edition/ref2.pdf)

SUMMARY

[Technical Problem]

In light of the current state of the art described above, an object to be achieved by the present invention is to provide a novel dyeing method for cellulose fiber fabrics with which cellulose fiber products dyed with a reactive dye which have high color fastness and do not undergo hydrolysis due to an alkali treatment can be obtained while reducing CO₂ emissions by increasing the pH while reducing the temperature of the washing liquid during washing after dyeing particularly in a dyeing method for cellulose fibers and products thereof using a nucleophilic addition type reactive dye.
In order to achieve this object, the present inventors have investigated reducing the temperature of the washing water used for washing after dyeing cellulose fibers and products thereof using a reactive dye, as described below.
As described above, in dyeing processing machines, washing is performed at high temperatures (generally around 90°C, but at least 75°C), which requires energy to raise the temperature and takes a long time to operate, resulting in increased CO₂ emissions.
However, if washing is performed at a lower temperature, the washing will not be sufficient, resulting in color fading (poor color fastness).
As described above, though there is a technique that can increase color fastness by washing with alkali, it is known that while alkali has the effect of increasing the dye washing effect, it further reacts with the dye that has already reacted to detach the bonds, causing poor fastness, or hydrolyzes the pigment itself, causing discoloration and fading.
In Patent Literature 1, though washing is performed at a high temperature (75 to 95°C) at a pH of approximately 9 to 10 (batch type dyeing) or a pH of 9 to 12 (continuous dyeing), this does not produce a significant effect, there is a risk of discoloration and poor fastness due to hydrolysis even in this relatively low pH range, and further, the treatment at such a relatively high temperature not only entails the risk of hydrolysis, but also produces the same amount of CO₂ emissions as in the prior art.
In Patent Literature 2, washing is performed at approximately 93°C and a pH of approximately 11. In this case, the risk of discoloration is much higher and the amount of CO₂ emissions is the same as in the prior art.
In Patent Literature 3, though the temperature is 75°C or lower in claims thereof, it is described that the problem to be solved by the invention is that it is "desired" to set the temperature to "70 to 75°C", and temperatures lower than that are not intended therein. Washing at 70 to 75°C and a pH of 10 to 12 does not produce a significant effect, and even in this relatively low pH range, there is a risk of discoloration and poor fastness due to hydrolysis.
In Patent Literature 4, though the washing temperature is 50 to 80°C in claims thereof, washing is performed at 80 to 85°C in all of the Examples. Washing at 80 to 85°C and a pH greater than 8 does not produce a significant effect, there is a risk of discoloration and poor fastness due to hydrolysis even in this relatively low pH range, and CO₂ emissions are not significantly improved as compared to conventional techniques.
Reactive dye species have two types of reactive groups: "nucleophilic addition type" and "nucleophilic substitution type." It has been found that the "nucleophilic addition type" reactive dye poses a particularly high risk of hydrolysis.

[Means for Solving Problem]

As a result of rigorous investigation and repeated experimentation in order to achieve the object described above, the present inventors have unexpectedly discovered that uniform dyed products without color unevenness which have high color fastness and do not undergo dye hydrolysis due to an alkali treatment can be obtained while reducing CO₂ emissions by increasing the pH while reducing the temperature of the washing liquid during washing after dyeing particularly in a dyeing method for cellulose fibers and products thereof using a nucleophilic addition type reactive dye, and have completed the present invention.
Specifically, the present invention is as follows.

[1] A dyeing method for cellulose fibers or a fiber product comprising cellulose fibers, the dyeing method being batch type or continuous type and comprising the following steps:
- a dyeing reaction step in which cellulose fibers or a fiber product comprising cellulose fibers are reacted with a reactive dye in a dyeing liquid;
- an alkaline washing step in which all or part of the dyeing liquid is discharged, and then the dyed fibers or fiber product are washed with an alkaline washing liquid having a pH of 10 to 14 and a temperature of 15 to 70°C; and
- a post-alkaline washing step of discharging the alkaline washing liquid and then washing with water.
[2] The dyeing method according to [1], wherein in the post-alkaline washing step, an acid is added to the water, and neutralization is carried out with an acid washing liquid containing an acid.
[3] The dyeing method according to [1] or [2], comprising, between the dyeing reaction step and the alkaline washing step, a pre-alkaline washing step of washing with an aqueous solution.
[4] The dyeing method according to any one of [1] to [3], wherein the dyeing method is a batch type dyeing method, and the alkaline washing liquid has a pH of 10 to 13 and a temperature of 15°C to 70°C or lower.
[5] The dyeing method according to any one of [1] to [3], wherein the dyeing method is a continuous type dyeing method, and the alkaline washing liquid has a pH of 12 to 14 and a temperature of 15 to 60°C.
[6] The dyeing method according to any one of [1] to [5], which satisfies the relationship represented by the following formula (1): $- 0.07 x + 13 \leq y < 0.07 x + 17$ where x is a temperature value from 15 to 70°C and y is a pH value from 10 to 14.
[7] The dyeing method according to any one of [1] to [6], wherein the dyeing liquid is maintained at a temperature of 5°C or higher and 70°C or lower throughout the alkaline washing step.
[8] The dyeing method according to any one of [1] to [7], wherein the reactive dye comprises a nucleophilic addition type reactive dye.
[9] The dyeing method according to any one of [3] to [8], wherein in the pre-alkaline washing step, washing is performed with water at a bath ratio of 1:100 or less and a temperature of 5 to 70°C.
[10] The dyeing method according to any one of [1] to [9], wherein in the alkaline washing step, washing is performed with an alkaline washing liquid at a bath ratio of 1:100 or less and a temperature of 15 to 70°C.
[11] The dyeing method according to any one of [1] to [10], wherein in the post-alkaline washing step, washing is performed with water at a bath ratio of 1:100 or less and a temperature of 5 to 70°C.

[Advantageous Effects of Invention]

According to the dyeing method of the present invention, cellulose fiber products dyed with a reactive dye which have high color fastness and do not undergo hydrolysis due to an alkali treatment can be obtained while reducing CO₂ emissions by increasing the pH while reducing the temperature of the washing liquid during washing after dyeing particularly in a dyeing method for cellulose fibers and products thereof using a nucleophilic addition type reactive dye.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a jet dyeing machine (an example of a batch type washing device) which can be used for each washing step of the dyeing method of the present invention.
FIG. 2 is a schematic view of an open soaper type continuous water washer (an example of a continuous batch type washing device) which can be used for each washing step of the dyeing method of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail below.
An embodiment of the present invention provides:
a dyeing method for cellulose fibers or a fiber product comprising cellulose fibers, the dyeing method being batch type or continuous type and comprising the following steps:

a dyeing reaction step in which cellulose fibers or a fiber product comprising cellulose fibers are reacted with a reactive dye in a dyeing liquid;
an alkaline washing step in which all or part of the dyeing liquid is discharged, and then the dyed fibers or fiber product are washed with an alkaline washing liquid having a pH of 10 to 14 and a temperature of 15 to 70°C; and
a post-alkaline washing step of discharging the alkaline washing liquid and then washing with water.

The form of cellulose fibers or fiber products comprising cellulose fibers to be dyed by the dyeing method of the present embodiment is not particularly limited, and various forms such as yarn, woven fabric, weft knitted fabric, non-woven fabric, and sewn products can be adopted. The cellulose fibers are not particularly limited, examples thereof include cotton, linen, rayon, cuprammonium rayon, lyocell, organic solvent-treated cellulose fibers, and ionic liquid-treated cellulose fibers, cotton, rayon, cuprammonium rayon, lyocell, and organic solvent-treated cellulose fibers are preferable, and cotton, rayon, and cuprammonium rayon are more preferable. Fibers other than cellulose fibers of a fiber product comprising cellulose fibers to be dyed by the dyeing method of the present embodiment can be dyed in combination with a known dyeing method.
The dyeing method of the present embodiment is not particularly limited, and may be either printing or solid dyeing, but is preferably solid dyeing. The reaction step of the dye in the dyeing method of the present embodiment may be, but is not limited to, a pad steaming dyeing, a pad batch dyeing, or a exhaust dyeing.
The equipment used in each washing step of the dyeing method of the present embodiment may be of a batch type or a continuous type, and is not particularly limited. As the equipment used in the batch type, a cheese dyeing machine, a skein dyeing machine, a jet dyeing machine, an air jet dyeing machine, a beam dyeing machine, a jigger dyeing machine, a winch dyeing machine, a rotary dyeing machine, a paddle dyeing machine, or a mini color dyeing machine is preferable, and a jet dyeing machine (refer to FIG. 1) is further preferable. As the equipment used in the continuous type, an open soaper type continuous water washer or a continuous winch dyeing machine is preferable, and an open soaper type continuous water washer (refer to FIG. 2) is further preferable.
The reactive dye used in the dyeing method of the present embodiment is preferably, for example, a reactive dye having a nucleophilic addition type reactive group, or a bifunctional or multifunctional reactive dye having nucleophilic addition type and nucleophilic substitution type reactive groups. Examples of the nucleophilic addition type reactive group include saturated alkane monocarboxylic acid amide, saturated alkane dicarboxylic acid amide, saturated alkane monocarboxylic acid, cycloalkane carboxamide, alkene monocarboxamide alkene dicarboxyamide, saturated aliphatic ketone, saturated aliphatic sulfonic acid amide, vinyl sulfamide, β-saturated ethyl sulfone, vinyl sulfone, and sulfate ethyl sulfonic acid reactive groups, and vinyl sulfone or sulfate ethyl sulfonic acid reactive groups are preferable. Examples of the nucleophilic substitution type reactive groups include pyridine, pyridazine, pyridazone, pyrimidine, S-triazine, 1,2,4-triazine, thiazole, benzoxazole, benzothiazole, quinoline, isoquinoline, quinoxaline, quinazoline, and phthalazine reactive groups, and 1,2,4-triazine reactive groups are preferable.
Examples of the inorganic salt used in the dyeing reaction method include, but are not limited to, sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, and mixtures thereof. Examples of the alkaline agent include, but are not limited to, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium metasilicate, trisodium phosphate, tripotassium phosphate, and mixtures thereof.
The dyeing method of the present embodiment includes the reactive dyeing step described above, an alkaline washing step for removing remaining dyes and the like after discharging the dyeing liquid from the dyeing bath, and a post-alkaline washing step of washing after discharging the alkaline washing liquid.

(Alkaline Washing Step)

The alkaline washing step will be explained in detail below.
The dyeing method of the present embodiment is directed to a dyeing method for cellulose fibers or a fiber product comprising cellulose fibers, the dyeing method being batch type or continuous type and comprising the following steps:

The alkaline washing step is a step with which cellulose fiber products dyed with a reactive dye which have high color fastness and do not undergo hydrolysis due to an alkali treatment can be obtained while reducing CO₂ emissions by increasing the pH while reducing the temperature of the washing liquid. Though this step is preferably a single treatment from the viewpoint of reducing the amount of alkali used and reducing the burden on drainage, a plurality of washing treatments may be included therein.
The alkaline washing liquid is an aqueous solution containing one or more types of alkali having a pH of 10 to 14 and a temperature of 15 to 70°C, can be selected from the viewpoint of the ease of hydrolysis of the dye used, the washing treatment time, and the required wet fastness, and from the viewpoint of CO₂ emissions and because the higher the temperature, the higher the risk of hydrolysis, the temperature thereof is preferably 15 to 60°C, more preferably 15 to 50°C. The pH thereof is preferably 10.5 to 14, and more preferably 11 to 14, because the higher the pH range, the easier the control and the higher the washability when an alkali is added.
The alkaline washing liquid is preferably an aqueous solution having a pH of 10 to 13 and a temperature of 15 to 70°C, since the treatment time is long and the risk of hydrolysis is high when the treatment is carried out in a batch type manner, and when the treatment is carried out in a continuous type manner, the pH is preferably 12 to 14 and the temperature is preferably 15 to 60°C because the treatment time is short and there is a high risk of insufficient washing while high temperatures generate steam containing alkali, which poses a danger to workability.
In order to eliminate the effects of hydrolysis caused by high temperature alkaline washing liquid, and to eliminate the lack of washing caused by low temperature alkaline washing liquid, the alkaline washing liquid is preferably an aqueous solution which satisfies the relationship represented by formula (1) below: $- 0.07 x + 13 \leq y < 0.07 x + 17$ where x is a temperature value from 15 to 70°C and y is a pH value from 10 to 14.
The alkaline washing liquid may contain components such as a dispersant, wetting agent, bath softener, bath leveling agent, emulsifier, and soaping agent, as desired.
The alkali contained in the alkaline washing liquid is not particularly limited, and examples thereof in include sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium metasilicate, trisodium phosphate, tripotassium phosphate, and mixtures thereof, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide are preferable, and sodium carbonate and sodium hydroxide are further preferable.

(Post-alkaline washing Step)

The post-alkaline washing method will be described in detail below.
The dyeing method of the present embodiment comprises a post-alkaline washing step in which all or part of the alkaline washing liquid is discharged, and then a post-alkaline washing liquid is added for washing.
The post-alkaline washing step is a step in which the fabric is treated with water, which is a post-alkaline washing liquid, in order to wash away the alkali used in the alkaline washing liquid. Though this step may be a single treatment, since residual alkali may cause serious complaints such as skin disorders or impair the functional processing in the subsequent finishing step, it is preferable for this step to include a plurality of washing treatments.
The temperature of the water used as the post-alkaline washing liquid is preferably 5°C to 70°C, and more preferably 5°C to 50°C, from the viewpoint of suppressing CO₂ emissions by keeping the temperature low, and since low temperatures are easily affected by air temperature, the temperature is further preferably 15°C to 50°C.
An acid may be added to the water serving as the post-alkaline washing liquid in order to eliminate residual alkali, and the acids that can be used are not particularly limited, and any of citric acid, malic acid, acetic acid, formic acid, sulfuric acid, nitric acid, hydrochloric acid, and oxalic acid can be used. The acid is preferably less corrosive to metals, and thus, formic acid, acetic acid, citric acid, or malic acid is more preferable. The water serving as the post-alkaline washing liquid may contain components such as a dispersant, wetting agent, bath softener, bath leveling agent, emulsifier, and soaping agent, as desired.

(Pre-Alkaline Washing Step)

Between the dyeing reaction step and the alkaline washing step, a pre-alkaline washing step of washing with an aqueous solution may be included.
Adding a pre-alkaline washing step is desirable from the viewpoint of eliminating high concentrations of salts, which have a dye exhausting effect, and enhancing the washing effect of the alkaline washing step.
The water used as the pre-alkaline washing liquid is not particularly limited, and may contain components such as a dispersant, wetting agent, bath softener, bath leveling agent, emulsifier, and soaping agent, as desired. However, water is preferable from the viewpoint of excluding salts.
The water serving as the pre-alkaline washing liquid is preferably at a temperature of 5°C to 70°C, and more preferably 5°C to 50°C, from the viewpoint of reducing CO₂ emissions by maintaining a low temperature, and the temperature is more preferably 15°C to 50°C, since low temperatures are easily affected by air temperature and make stable dyeing difficult.
The bath ratio of the alkaline washing step, post-alkaline washing step, and pre-alkaline washing step depends on the washing machine, and if the processing amount is large with a continuous type washing machine, the bath ratio may be higher than 1:1. As the bath ratio increases, the amount of CO₂ emitted during heating of the washing liquid increases, so it is preferably 1:100 or less, more preferably 1:30 or less.

EXAMPLES

The present invention will be specifically described below using Examples and Comparative Examples, but the present invention is not limited to the Examples. The calculation of the amount of CO₂ emission reduction and various evaluations of each yarn or fiber product of the Examples were performed by the following methods.

(1) Calculation of CO₂ Emission

The power consumption and steam consumption required for the operation of the dyeing machine were measured and CO₂ emission (kg-CO₂ e) was determined using the following formula: $W = E \times α + S \times β$ where W: CO₂ emission (kg-CO₂e), E: power consumption (MJ), S: steam consumption (MJ), α: CO₂ intensity of electricity (kg-CO₂e/MJ), and β: CO₂ intensity of steam (kg-CO₂e/MJ). α and β are respectively the CO2 intensities of electricity and steam at a certain point in time (kg-CO₂e/MJ), and are values published by the Ministry of the Environment. The CO₂ intensity at a certain point in time is not particularly limited, but may be exemplified by the CO₂ intensity described in the Non-Patent Literature 1: "Reference Material 2, List of Calculation Formulas and Emission Factors for Calculating Greenhouse Gas Emissions (https://www.env.go.jp/earth/ondanka/suishin_g/3rd_edition/ref2.pdf)." For example, the intensity of electricity, α, is 0.1542 (kg-CO₂e/MJ), and the intensity of steam, β, is 0.0600 (kg-CO₂e/MJ). In the following Examples, the CO₂ emission (kg-CO₂e) is calculated using the intensities of α = 0.1542 (kg-CO₂e/MJ) and β = 0.0600 (kg-CO₂e/MJ). In Comparative Examples for each dyeing method, material type, and dye usage, when using a conventional water washing method as a "blank", the case in which the CO₂ emissions (kg-CO₂e) are reduced as compared to the blank is judged as "improved", and the case in which there is no change as compared to the blank is evaluated as "equivalent."

(2) Color Fading

The color of the dyed fiber product is measured using a spectrophotometer (model Color-Eye 7000A manufactured by GretagMacbeth) under the conditions of a D56 light source and a viewing angle of 10 degrees, and the L* value in the CIE1976L*a*b* color space is determined. In Comparative Examples for each dyeing method, material type, and dye usage, when using a conventional water washing method as a "blank", the ΔL* value is calculated by the following formula: $ΔL * value = L * value of blank - L * value of measured product$
When the ΔL* value is 0.5 or less, there is no color fading and the condition is judged to be suitable. When the ΔL* value is greater than 0.5 and 1.0 or less, the condition is judged to be "slightly worse", and when the ΔL* value exceeds 1.0, the condition is judged to be "worse."

(3) Fastness to Sweat

A sweat fastness test is conducted in accordance with the test method for color fastness to sweat specified in JIS L 0848. A multi-fiber co-woven fabric, in which eight types of fibers (cotton, nylon, acetate, wool, rayon, acrylic, silk, and polyester) are co-woven in a vertical stripe pattern, in accordance with JIS L 0803 is used as the standard adjacent fabric. In Comparative Examples for each dyeing method, material type, and dye usage, when a conventional water washing method is used as a "blank", the total of the fastness to acid sweat and fastness to alkaline sweat is compared with the blank, a larger number is judged as "improved", the same number is judged as "equivalent", and a smaller number is judged as "worse."

(4) Product to be Dyed

In Examples and Comparative Examples, cupra knitted fabrics and cotton knitted fabrics are used as products to be dyed. They are obtained as follows:

A cupra knitted fabric is prepared as follows:
5 parts of 167 dtex cupra fiber, which is a regenerated cellulose fiber, knitted with one feeder using a 24-gauge single-feed test circular knitting machine (model NCR-ES manufactured by EIKO Industrial Co., Ltd.), is treated in a bath containing 0.1 parts of sodium carbonate and 0.1 parts of surfactant Score Roll (manufactured by Hokko Chemicals Co., Ltd.) dissolved in 100 parts of water at a liquid temperature of 90°C for 30 minutes, and then dehydration and drying are performed to obtain a cupra knitted fabric as a product to be dyed.
A cotton knitted fabric is prepared as follows:
An undyed unmercerized cotton knitted fabric produced by scouring and bleaching a general-purpose circular interlock knitted gray fabric composed of cotton is obtained and treated as a product to be dyed.
A cupra woven fabric is prepared as follows:
An undyed cupra fabric is obtained by scouring a woven gray fabric in which 110 dtex cupra fibers are weft-inserted to a warp of 84 dtex cupra fibers with a loom, and treated as a product to be dyed.

[Comparative Example 1a]

Dyeing step: Dyeing was performed using a mini-color dyeing machine (UR-MINI-COLOR manufactured by Texam Giken Co., Ltd.) as a batch type dyeing method. First, the dyeing reaction step was performed. 140 parts of water at 20°C were placed in a stainless-steel pot having a diameter of 72 mm and a height of 110 mm, and 5 parts of the cupra knitted fabric were introduced as the product to be dyed. Thereafter, a total of 5 parts of a reactive dye having a nucleophilic addition type reactive group (0.125 parts of Remazol BrRed BB 150% (manufactured by Dystar Japan, Ltd.), 0.0625 parts of Remazol BrYellow GL 150% (manufactured by Dystar Japan, Ltd.), and 0.0625 parts of KPZOL BLACK B 150 POWDER (manufactured by Kiwa Chemical Industry Co., Ltd.)) were introduced thereto. Thereafter, the liquid temperature was raised to 60°C, 7.5 parts of sodium sulfate were added thereto, the dye was exhausted, 2.25 parts of sodium carbonate were added thereto, and the liquid was maintained at 60°C for 30 minutes to react with the dye. 120 parts of the dyeing liquid was then removed to obtain a dyed product before the washing step.
Next, a total of four washing steps were performed as the washing step. In each step, the temperature was raised from an initial temperature of 15°C at a rate of 3°C/min. The initial temperature and the rate of temperature rise were the same in all of the following Examples and Comparative Examples.
First washing step: 70 parts of water was added, the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Second washing step: 70 parts of a solution in which 0.25 parts of acetic acid was dissolved in water was added, and the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Third washing step: 70 parts of water was added, the temperature was raised to 90°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Fourth washing step: 70 parts of water was added, the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing. The dyed fabric was then removed, dehydrated, and dried by a known method to obtain a dyed product after the washing step.
The dyed product after the washing step was evaluated for color fading and fastness to sweat. The CO₂ emissions during the dyeing and washing steps were calculated.

[Comparative Examples 1b and 1c and Examples 1a to 1d]

Five parts of the cupra knitted fabric as a product to be dyed were reacted with the dye using the dye and method of Comparative Example 1a, and the liquid was removed to obtain a dyed product before the washing step.
Next, for the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration, and drying were performed by the same procedure as in Comparative Example 1a to obtain a dyed product after the washing step.
The evaluations of color fading, fastness to sweat, and CO₂ emissions were compared with Comparative Example 1a. The comparison results are summarized in Table 2 below.

[Comparative Examples 2a and 2b and Examples 2a and 2b]

Dyeing step: The dye was reacted using the same dye and method as in Comparative Example 1a, except that the product to be dyed was changed to 5 parts of the cotton knitted fabric, and the liquid was removed to obtain a dyed product before the washing step.
Next, for the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration, and drying were performed by the same procedure as in Comparative Example 1a to obtain a dyed product after the washing step.
The evaluation results and comparison results for color fading, fastness to sweat, and CO₂ emissions are summarized in Table 2 below.

[Comparative Example 3a]

Dyeing step: The dye was reacted using the same dye and method as in Comparative Example 1a, except that the product to be dyed was changed to 5 parts of the cotton knitted fabric, and the liquid was removed to obtain a dyed product before the washing step.
Next, as a washing step, a total of six washing treatments was carried out.
First washing step: 70 parts of water was added, the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Second washing step: 70 parts of a solution of 0.4 parts of acetic acid dissolved in water was added, the temperature was raised to 30°C, and the mixture was maintained for 10 minutes to preform washing, after which 70 parts of the washing liquid was removed.
Third washing step: 70 parts of a solution containing 0.2 parts of soaping agent Meisanol KHM (Meisei Chemical Works, Ltd.) was added, the temperature was raised to 90°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Fourth washing step: 70 parts of water was added, the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Fifth washing step: 70 parts of water was added, the temperature was raised to 20°Cs, and the temperature was maintained for 10 minutes to perform washing, after which 70 parts of the washing liquid was removed.
Sixth washing step: 70 parts of water was added, the temperature was raised to 20°C, and the temperature was maintained for 10 minutes to perform washing. The dyed fabric was then removed, dehydrated, and dried by a known method to obtain a dyed product after the washing step.
The dyed product after the washing step was evaluated for color fading and fastness to sweat. In addition, the CO₂ emissions during the dyeing and washing steps were calculated.

[Comparative Examples 3b to 3d and Examples 3a to 3g]

Dyeing step: Five parts of the cotton knitted fabric as a product to be dyed were reacted with the dye using the same dye and method as in Comparative Example 1a, and the liquid was removed to obtain a dyed product before the washing step.
Next, as the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration, and drying were performed by the same procedure as Comparative Example 3a, to obtain a dyed product after the washing step.
The evaluations of color fading, fastness to sweat, and CO₂ emissions were compared with Comparative Example 3a. The comparison results are summarized in Table 2 below.

[Comparative Example 4a and Examples 4a and 4b]

Dyeing step: using 5 parts of the cupra knitted fabric as a product to be dyed, the dye was reacted in the same manner as in Comparative Example 1a, except that a total of 0.25 parts of reactive dye having a nucleophilic addition type reactive group and a nucleophilic substitution type reactive group (0.125 parts of Remazol Red RGB (manufactured by Dystar Japan, Ltd.), 0.0675 parts of Remazol GoldYellow RGB (manufactured by Dystar Japan, Ltd.), and 0.0675 parts of Remazol Navy RGB (manufactured by Dystar Japan, Ltd.)) was used, and the liquid was removed to obtain a dyed product before the washing step.
Next, as the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration, and drying were performed by the same procedure as Comparative Example 1a, to obtain a dyed product after the washing step.
The evaluations and comparison results of color fading, fastness to sweat, and CO₂ emissions are summarized in Table 2 below.

[Comparative Examples 5a to 5c and Examples 5a and 5b]

Dyeing step: Five parts of the cotton knitted fabric as a product to be dyed were reacted with the dye using the dye and method of Comparative Example 4a, and the liquid was removed to obtain a dyed product before the washing step.
Next, as the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration, and drying were performed by the same procedure as Comparative Example 3a to obtain a dyed product after the washing step.
The evaluations and comparison results of color fading, fastness to sweat, and CO₂ emissions are summarized in Table 2 below.

[Comparative Example 6a]

Dyeing step: Pad-steam dyeing was performed as a continuous type dyeing method. First, the dyeing reaction step was performed. 10 parts of the cupra woven fabric as a product to be dyed was impregnated with 100 parts of an aqueous solution containing 5 parts of a reactive dye Remazol BrRed BB 150% (manufactured by Dystar Japan, Ltd.) having a nucleophilic addition type reactive group, 5 parts of sodium sulfate, and 1 part of sodium hydroxide, and padding treatment of squeezing using a mangle to achieve a pickup rate of 80% was repeated twice using the same solution. Using a press machine applicable to the JIS L1096H method press dimensional change rate, the test sample and a filter paper were set on the lower plate, the upper plate was lowered to 20 mm above the test sample, and steam of 490 kPa set at 100°C was ejected for 90 seconds to perform a steaming treatment, thereby completing the dyeing reaction step to obtain a dyed product before the washing step.
Next, as the washing step, a total of five washing treatments was performed.
First washing step: After impregnating with 100 parts of water heated to 30°C for 10 seconds, washing was performed by twice repeating the treatment of squeezing using a mangle to achieve a pickup rate of 80% using the same solution.
Second washing step: After impregnating with 100 parts of an aqueous solution containing 0.02 parts of citric acid and 0.02 parts of the soaping agent Meisanol KHM (Meisei Chemical Works, Ltd.) heated to 80°C for 10 seconds, washing was performed by twice repeating the treatment of squeezing using a mangle to achieve a pickup rate of 80% using the same solution.
Third washing step: The third washing step was carried out in the same manner as the second washing step.
Fourth washing step: After impregnating with 100 parts of water heated to 430°C for 10 seconds, washing was performed by twice repeating the treatment of squeezing using a mangle to achieve a pickup rate of 80% using the same solution.
Fifth washing step: The fifth washing step was carried out in the same manner as the fourth washing step. Finally, the fabric was dried by a known method to obtain a dyed product after the washing step.

[Example 6b]

Dyeing step: 10 parts of cupra woven fabric as a product to be dyed were dyed using the same dye and method as in Example 6a to obtain a dyed product before the washing step.
Next, as the washing step, the washing liquid and temperature were changed as shown in Table 1 below, and washing, dehydration and drying were performed by the same procedure as in Comparative Example 6a to obtain a dyed product after the washing step.

The evaluations of color fading, fastness to sweat, and CO₂ emissions were compared with Comparative Example 6a. The comparison results are summarized in Table 2 below.

[Table 1]

	Material	Dye used		Dyeing method	Number of washing steps	Alkali washing liquid			Washing step (washing liquid and temp)
	Material	Reactive group	Dye concentration	Dyeing method	Number of washing steps	pH		Temp	First	Second	Third	Fourth	Fifth	Sixth
Comp Ex 1a	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	-	-	-	20°C water	20°C acid neutralization	90°C water	20°C water	-	-
Comp Ex 1b	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	-	-	-	40°C water	40°C acid neutralization	40°C water	40°C water	-	-
Comp Ex 1c	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	10.8	Sodium carbonate	90	20°C water	90°C alkali	20°C acid neutralization	20°C water	-	-
Ex 1a	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	10.7	Sodium carbonate	40	40°C water	40°C alkali	40°C water	20°C acid neutralization	-	-
Ex 1b	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	11.8	NaOH	60	20°C water	60°C alkali	20°C acid neutralization	20°C water	-	-
Ex 1c	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	12.1	NaOH	40	40°C alkali	40°C water	40°C acid neutralization	20°C water	-	-
Ex 1d	Cupra	Nucleophilic addition	5%o.w.f	Batch type	4	13.2	NaOH	40	40°C water	40°C alkali	40°C acid neutralization	20°C water	-	-
Comp Ex 2a	Cotton	Nucleophilic addition	5%o.w.f	Batch type	4	-	-	-	20°C water	20°C acid neutralization	20°C water	90°C water	-	-
Comp Ex 2b	Cotton	Nucleophilic addition	5%o.w.f	Batch type	4	9.2	Sodium carbonate	90	20°C acid neutralization	90°C alkali	20°C acid neutralization	20°C water	-	-
Ex 2a	Cotton	Nucleophilic addition	5%o.w.f	Batch type	4	13.2	NaOH	20	20°C water	20°C alkali	20°C acid neutralization	20°C water	-	-
Ex 2b	Cotton	Nucleophilic addition	5%o.w.f	Batch type	4	11	Sodium carbonate	70	70°C alkali	20°C water	20°C water	20°C acid neutralization	-	-
Comp Ex 3a	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	-	-	-	20°C water	30°C acid neutralization	90°C soaping agent	20°C water	20°C water	20°C water
Comp Ex 3b	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	-	-	-	20°C water	30°C acid neutralization	70°C soaping agent	20°C water	20°C water	20°C water
Comp Ex 3c	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	14.2	NaOH	30	20°C water	30°C alkali	20°C acid neutralization	70°C soaping agent	20°C water	20°C water
Comp Ex 3d	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	9.8	Sodium carbonate	60	20°C water	30°C acid neutralization	60°C alkali + soaping agent	20°C acid neutralization	20°C water	20°C water
Ex 3a	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	12.8	NaOH	30	20°C water	30°C alkali	20°C acid neutralization	70°C soaping agent	20°C water	20°C water
Ex 3b	Cotton	Nucleophilic	5%o.w.f	Batch type	6	12.5	NaOH	70	20°C water	30°C water	70°C alkali +	20°C acid	20°C water	20°C
		addition									soaping agent	neutralization		water
Ex 3c	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	11.1	NaOH	30	20°C water	30°C alkali	20°C acid neutralization	70°C soaping agent	20°C water	20°C water
Ex 3d	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	11.4	NaOH	60	20°C water	30°C water	60°C alkali + soaping agent	20°C acid neutralization	20°C water	20°C water
Ex 3e	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	13.6	NaOH	50	30°C water	20°C water	50°C alkali + soaping agent	20°C water	20°C acid neutralization	20°C water
Ex 3f	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	11.96	NaOH	50	30°C water	20°C water	50°C alkali + soaping agent	20°C water	20°C acid neutralization	20°C water
Ex 3g	Cotton	Nucleophilic addition	5%o.w.f	Batch type	6	10.5	Sodium carbonate	50	30°C water	20°C water	50°C alkali + soaping agent	20°C water	20°C acid neutralization	20°C water
Comp Ex 4a	Cupra	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	4	-	-	-	20°C water	20°C acid neutralization	90°C water	20°C water	-	-
Ex 4b	Cupra	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	4	12.5	NaOH	60	20°C water	60°C alkali	20°C acid neutralization	20°C water	-	-
Ex 4a	Cupra	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	4	13.1	NaOH	60	20°C water	60°C alkali	20°C acid neutralization	20°C water	-	-
Comp Ex 5a	Cotton	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	6	-	-	-	20°C water	30°C acid neutralization	90°C soaping agent	20°C water	20°C water	20°C water
Comp Ex 5b	Cotton	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	6	14.4	NaOH	30	20°C water	30°C alkali	20°C acid neutralization	70°C soaping agent	20°C water	20°C water
Comp Ex 5c	Cotton	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	6	9.8	Sodium carbonate	60	20°C water	30°C acid neutralization	60°C alkali + soaping agent	20°C acid neutralization	20°C water	20°C water
Ex 5a	Cotton	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	6	11.4	NaOH	30	20°C water	30°C alkali	20°C acid neutralization	70°C soaping agent	20°C water	20°C water
Ex 5b	Cotton	Nucleophilic addition + Nucleophilic substitution	5%o.w.f	Batch type	6	11.4	NaOH	60	20°C water	30°C water	60°C alkali + soaping agent	20°C acid neutralization	20°C water	20°C water
Comp Ex 6a	Cupra	Nucleophilic addition	50 g/L	Continuous type	5	-	-	-	20°C water	80°C acid neutralization	80°C acid neutralization	20°C water	20°C water	-
Ex 6a	Cupra	Nucleophilic addition	50 g/L	Continuous type	5	12.2	NaOH	40	20°C water	40°C alkali	40°C alkali	20°C acid neutralization	20°C water	-

[Table 2]

Example	Comparison target	Color fading		Fastness to sweat			CO2 emissions [kg-CO₂e]
Example	Comparison target	*ΔL value	Judgement	Acid (grade)	Alkali (grade)	Judgement	Emissions	Judgement
Comp Ex 1a	Comp Ex 1a	0	Blank	2	2	Blank	0.0146	Blank
Comp Ex 1b	Comp Ex 1a	-0.28	Equivalent	1-2	1-2	Worse	0.0127	Improved
Comp Ex 1c	Comp Ex 1a	1.15	Worse	1-2	1-2	Worse	0.0146	Equivalent
Ex 1a	Comp Ex 1a	0.11	Equivalent	2	2	Equivalent	0.0127	Improved
Ex 1b	Comp Ex 1a	0	Equivalent	2	2	Equivalent	0.0102	Improved
Ex 1c	Comp Ex 1a	0.17	Equivalent	2	2	Equivalent	0.0127	Improved
Ex 1d	Comp Ex 1a	-0.01	Equivalent	2-3	3	Improved	0.0127	Improved
Comp Ex 2a	Comp Ex 2a		Blank	1-2	2	Blank	0.0146	Blank
Comp Ex 2b	Comp Ex 2a	0.08	Equivalent	1-2	2	Equivalent	0.0146	Equivalent
Ex 2a	Comp Ex 2a	-0.03	Equivalent	2-3	2-3	Improved	0.0055	Improved
Ex 2b	Comp Ex 2a	0.91	Slightly worse	1-2	2	Equivalent	0.0115	Improved
Comp Ex 3a	Comp Ex 3a	0	Blank	2-3	2-3	Blank	0.0199	Blank
Comp Ex 3b	Comp Ex 3a	-0.22	Equivalent	2	2-3	Worse	0.0167	Improved
Comp Ex 3c	Comp Ex 3a	0.18	Equivalent	1	1-2	Worse	0.0167	Improved
Comp Ex 3d	Comp Ex 3a	-0.24	Equivalent	2	2-3	Worse	0.0155	Improved
Ex 3a	Comp Ex 3a	-0.2	Equivalent	3-4	3	Improved	0.0167	Improved
Ex 3b	Comp Ex 3a	0.67	Slightly worse	3	2-3	Improved	0.0167	Improved
Ex 3c	Comp Ex 3a	-0.66	Equivalent	3-4	3	Improved	0.0167	Improved
Ex 3d	Comp Ex 3a	-0.45	Equivalent	2-3	2-3	Equivalent	0.0155	Improved
Ex 3e	Comp Ex 3a	1.17	Worse	3	3-4	Improved	0.0142	Improved
Ex 3f	Comp Ex 3a	-0.01	Equivalent	2-3	3	Improved	0.0142	Improved
Ex 3g	Comp Ex 3a	-0.27	Equivalent	2-3	2-3	Equivalent	0.0142	Improved
Comp Ex 4a	Comp Ex 4a	0	Blank	3-4	3	Blank	0.0146	Blank
Ex 4a	Comp Ex 4a	0.12	Equivalent	3	3-4	Improved	0.0102	Improved
Ex 4b	Comp Ex 4a	-0.06	Equivalent	2	2-3	Worse	0.0102	Improved
Comp Ex 5a	Comp Ex 5a	0	Blank	3-4	3-4	Blank	0.0199	Blank
Comp Ex 5b	Comp Ex 5a	1.1	Worse	2	2	Worse	0.0167	Improved
Comp Ex 5c	Comp Ex 5a	-0.08	Equivalent	3	3	Worse	0.0155	Improved
Ex 5a	Comp Ex 5a	0.1	Equivalent	4	4	Improved	0.0167	Improved
Ex 5b	Comp Ex 5a	0.25	Equivalent	3-4	3-4	Improved	0.0155	Improved
Comp Ex 6a	Comp Ex 6a	0	Blank	3-4	3-4	Blank	0.0116	Blank
Ex 6a	Comp Ex 6a	0.1	Equivalent	3-4	3-4	Equivalent	0.0051	Improved

In Comparative Examples 1a to c and Examples 1a to d, which constitute a sample group in which the batch type dyeing method, the cupra knitted fabric as a dyed product, a nucleophilic addition reactive type dye, and four washing steps were used, all of Examples 1a to d, as compared to Comparative Example 1a, in which alkaline washing was not performed, were confirmed to achieve no hydrolysis, improved fastness to sweat, and reduced CO₂ emissions.
Comparative Example 1b, in which alkaline washing was not performed, though low-temperature dyeing at a low temperature was performed, was worse as compared to Comparative Example 1a. Comparative Example 1c, where though an alkaline washing step was performed, the temperature range was 90°C, can be confirmed to undergo hydrolysis, color fading, and worse fastness.
In Comparative Examples 2a and b and Examples 2a and b, which constitute a sample group in which the batch type dyeing method, the cotton knitted fabric as a dyed product, a nucleophilic addition reactive dye, and four washing steps were used, it can be confirmed that Example 2a, as compared to Comparative Example 2a, in which alkaline washing was not performed, achieved no hydrolysis, improved fastness to sweat, and reduced CO₂ emissions. In Example 2b, the temperature was 70°C and the pH was 11, and CO₂ emissions were reduced and fastness was the equivalent, but color fading due to hydrolysis was confirmed.
In Comparative Example 2b, though an alkaline washing step was performed, the temperature range was 90°C and even though the pH range was low at 9.4, worse fastness due to hydrolysis occurred.
In Comparative Examples 3a to d and Examples 3a to g, which constitute a sample group in which the batch type dyeing method, the cotton knitted fabric as a dyed product, a nucleophilic addition reactive dye, and six washing steps were used, it can be confirmed that Examples 3a, c, d, f, and g achieved no hydrolysis, improved fastness to sweat, and reduced CO₂ emissions as compared to Comparative Examples 3a and b, in which alkaline washing was not performed. In Example 3b, the temperature was 70°C and the pH was 12.5, and in Example 3e, the temperature was 50°C and the pH was 13.6, and color fading due to hydrolysis was confirmed, but the CO₂ emissions were reduced.
In Comparative Example 3b, an alkaline washing step was not performed and the temperature range was 70°C, and the CO₂ emissions were reduced but fastness was worse due to insufficient washing, as compared to Comparative Example 3a.
In Comparative Example 3c, though an alkaline washing step was performed, the temperature was 30°C and the pH was 14.2, which was higher than pH 14, and the CO₂ emissions were reduced but fastness was significantly worse due to hydrolysis, as compared to Comparative Example 3a.
In Comparative Example 3d, though an alkaline washing step was performed, the temperature was 60°C and the pH was 9.8, which was below pH 10, and the CO₂ emissions were reduced but the fastness was significantly worse due to insufficient washing, as compared to Comparative Example 3a.
In Comparative Example 4a and Examples 4a and b, which constitute a sample group in which the batch type dyeing method, the cupra knitted fabric as a dyed product, a reactive dye having both nucleophilic addition and nucleophilic substitution reactive groups, and four washing steps was used, it can be confirmed that Example 4a achieved no hydrolysis, improved fastness to sweat, and reduced CO₂ emission as compared to Comparative Example 4a, in which alkaline washing was not performed. In Example 4b, the temperature was 60°C and the pH was 13.1, and though color fading due to hydrolysis was confirmed, the CO₂ emissions were reduced.
In Comparative Examples 5a to c and 5a to b, which constitute a sample group in which the batch type dyeing method, the cotton knitted fabric as a dyed product, a reactive dye having both nucleophilic addition and nucleophilic substitution reactive groups, and six washing steps was used, it can be confirmed that both Examples 5a and b achieved no hydrolysis, improved fastness to sweat, and reduced CO₂ emissions as compared to Comparative Example 5a, in which alkaline washing was not performed.
In Comparative Example 5b, though an alkaline washing step was performed, the temperature was 30°C and the pH was 14.4, which was higher than pH 14, and the CO₂ emissions were reduced but fastness was significantly worse due to hydrolysis, as compared to Comparative Example 3a.
In Comparative Example 5c, though an alkaline washing step was performed, the temperature was 60°C and the pH was 9.8, which was below pH 10, and the CO₂ emissions were reduced but fastness was significantly worse due to insufficient washing, as compared to Comparative Example 3a.
In Comparative Example 6a and Example 6a, which constitute a sample group in which the continuous type dyeing method, the cupra woven fabric as a dyed product, a nucleophilic addition type reactive dye, and five washing steps were used, it can be confirmed that Example 6a achieved no hydrolysis, equivalent fastness to sweat, and reduced CO₂ emissions, as compared to Comparative Example 6a, in which alkaline washing was not performed.

[Industrial Applicability]

According to the present invention, since there can be provided a novel dyeing method with which cellulose fiber products dyed with a reactive dye which have high color fastness and do not undergo hydrolysis due to an alkali treatment can be obtained while reducing CO₂ emissions by increasing the pH while reducing the temperature of the washing liquid during washing after dyeing particularly in a dyeing method for cellulose fibers and products thereof using a nucleophilic addition type reactive dye, the present invention can suitably be applied to the dyeing of cellulose fibers and products thereof using a reactive dye.

[Reference Signs List]

1: jet dyeing machine
2: reserve tank
3: heat exchanger
4: nozzle
5: fabric
6: dyeing bath
7: reaction step machine: pad steaming dyeing machine
8: fabric before dyeing (reaction step, washing step)
9: dyeing bath
10: mangle
11: steam box
12: washing step machine: open soaper continuous water washer
13: cylinder dryer
14: fabric after dyeing (reaction step, washing step)

Claims

A dyeing method for cellulose fibers or a fiber product comprising cellulose fibers, the dyeing method being batch type or continuous type and comprising the following steps:
a dyeing reaction step in which cellulose fibers or a fiber product comprising cellulose fibers are reacted with a reactive dye in a dyeing liquid;

an alkaline washing step in which all or part of the dyeing liquid is discharged, and then the dyed fibers or fiber product are washed with an alkaline washing liquid having a pH of 10 to 14 and a temperature of 15 to 70°C; and

a post-alkaline washing step of discharging the alkaline washing liquid and then washing with water.
The dyeing method according to claim 1, wherein in the post-alkaline washing step, an acid is added to the water, and neutralization is carried out with an acid washing liquid containing an acid.
The dyeing method according to claim 1 or 2, comprising, between the dyeing reaction step and the alkaline washing step, a pre-alkaline washing step of washing with an aqueous solution.
The dyeing method according to claim 1 or 2, wherein the dyeing method is a batch type dyeing method, and the alkaline washing liquid has a pH of 10 to 13 and a temperature of 15°C to 70°C or lower.
The dyeing method according to claim 1 or 2, wherein the dyeing method is a continuous type dyeing method, and the alkaline washing liquid has a pH of 12 to 14 and a temperature of 15 to 60°C.
The dyeing method according to claim 1 or 2, which satisfies the relationship represented by the following formula (1): $- 0.07 x + 13 \leq y < 0.07 x + 17$ where x is a temperature value from 15 to 70°C and y is a pH value from 10 to 14.
The dyeing method according to claim 1 or 2, wherein the dyeing liquid is maintained at a temperature of 5°C or higher and 70°C or lower throughout the alkaline washing step.
The dyeing method according to claim 1 or 2, wherein the reactive dye comprises a nucleophilic addition type reactive dye.
The dyeing method according to claim 3, wherein in the pre-alkaline washing step, washing is performed with water at a bath ratio of 1:100 or less and a temperature of 5 to 70°C.
The dyeing method according to claim 1 or 2, wherein in the alkaline washing step, washing is performed with an alkaline washing liquid at a bath ratio of 1:100 or less and a temperature of 15 to 70°C.
The dyeing method according to claim 1 or 2, wherein in the post-alkaline washing step, washing is performed with water at a bath ratio of 1:100 or less and a temperature of 5 to 70°C.