EP4722445A1

EP4722445A1 - Method for dyeing cellulose-based fiber product

Info

Publication number: EP4722445A1
Application number: EP24815460.1A
Authority: EP
Inventors: Motoya MATSUBARA
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: JP7654910B1; WO2024247977A1; TWI902273B; TW202503144A; JP2025085771A; JPWO2024247977A1; CN121039341A

Abstract

A dyeing method, including the steps of feeding water of a first temperature region of 5°C or higher and lower than 30°C or a second temperature region of 30°C or higher and lower than 40°C to a dyeing bath and introducing cellulose fibers or a fiber product containing cellulose fibers thereto, under the proviso that the water-feeding and the introducing are performed in any order, raising the temperature from the first temperature region to a second temperature region of 30°C or higher and lower than 40°C and from the second temperature region to a third temperature region of 40°C or higher and lower than 70°C, or alternatively, raising the temperature from the second temperature region to the third temperature region of 40°C or higher and 70°C or lower, maintaining a third temperature within the third temperature region for a predetermined period of time, introducing a reactive dye at a temperature higher than the first temperature region; and introducing a mixture of an inorganic salt and an alkaline agent in three or more divided portions separately from introducing the reactive dye at a temperature equal to or higher than the second temperature region.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to a dyeing method for cellulose fibers or a fiber product containing cellulose fibers using a reactive dye.

2. Description of the Related Art

In industrial exhaust dyeing, when a reactive dye is used, an inorganic salt and an alkaline agent are introduced into a dyeing bath together with the reactive dye, and exhaust dyeing with the reactive dye is carried out. The presence of the inorganic salt is necessary to promote the absorption of the dye into the cellulose fibers, while the 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 uniformly dyed products. In the dyeing process of the prior art, the inorganic salt is introduced in a divided manner as desired into a dyeing bath in which water, fabric, and dye are uniformly dispersed, and after the introduction of the inorganic salt is complete, the alkaline agent is also introduced in a divided manner as desired.
However, in conventionally-known techniques, since it takes a long time to obtain uniformly dyed products with high color fastness and no color unevenness, a large amount of electricity to operate the dyeing device and steam to maintain temperature are required, resulting in a problem of large CO₂ emissions.
Patent Literature 1 below proposes an exhaust dyeing method for shortening dyeing time, in which a reactive dye having a specific molecular structure is used and is introduced together with an inorganic salt and an alkaline agent.
However, in the method of introducing an inorganic salt and an alkaline agent together at once, since it is difficult to dissolve the inorganic salt, time is required for dissolving the inorganic salt, resulting in a problem that the workability becomes complicated. Furthermore, by introducing the inorganic salt all at once, a phenomenon occurs in which the dye is instantaneously absorbed into the cellulose fibers, making it impossible to obtain a sufficient dyeing result from the viewpoint of obtaining a uniformly dyed product.
Patent Literature 2 below describes a method of dividing and introducing an inorganic salt and an alkaline agent, in which the inorganic salt and the alkaline agent are optimally introduced in small amounts per unit time in accordance with a linear function or in accordance with a positive or negative exponential, logarithmic, or power function.
However, in the technique of Patent Literature 2, though the inorganic salt and the alkaline agent are optimally introduced in infinite steps using special dedicated equipment, in order to determine the optimal rate of introduction of inorganic salts and alkaline agents, it is necessary to perform a series of exhaustion dyeing tests in advance and calculate from the addition function of the isothermal exhaustion curve using a computer program, and when the simultaneous addition rate of the inorganic salt and the alkaline agent varies according to a non-linear addition function, it is necessary that this function be determined using a data processing unit (for example a personal computer). Specifically, there is a problem in that extremely complicated and troublesome work is required to determine the addition rate, and mathematical knowledge is also required. In order to achieve the calculated addition rate, which would not be possible manually, dedicated equipment for measuring the addition into the dyeing bath in real time during the dyeing process is required, which is not something that can be easily implemented as it requires capital investment. This is particularly true in developing countries.
Patent Literature 3 below proposes a method of introducing an inorganic salt and an alkaline agent in portions after mixing them, in which the inorganic salt and the alkaline agent are introduced quantitatively and continuously, as represented by any of three specific curves.
However, in the technique of Patent Literature 3, in order to realize the addition rate represented by any of the three specific curves, since this is impossible to do manually, dedicated equipment for the addition into the dyeing bath is required, which is not something that can be easily implemented as it requires capital investment. This is particularly true in developing countries.
A dyeing method for cellulose fiber fabrics which reduces CO₂ emissions by shortening the dyeing time, simplifies the dyeing operation, and produces uniformly dyed products with high color fastness and no color unevenness has not been provided at present.

[Citation List]

[Patent Literature]

[PTL 1] Japanese Unexamined Patent Publication (Kokai) No. 63-211379
[PTL 2] Japanese Unexamined Patent Publication (Kokai) No. 60-259687
[PTL 3] Japanese Unexamined Patent Publication (Kokai) No. 01-118680

[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 which can reduce CO₂ emissions by shortening dyeing time, simplify dyeing operations, and produce uniformly dyed products with high color fastness and no color unevenness.

[Means for Solving Problem]

As a result of rigorous investigation and repeated experimentation to achieve the object described above, the present inventors have unexpectedly discovered that by introducing a mixture of an inorganic salt and an alkaline agent in divided portions for a predetermined number of times, and optimizing the temperature of the dyeing liquid and the introduction timing, even without using the special dedicated equipment described above, it is possible to obtain uniformly dyed products with high color fastness and no color unevenness, and have completed the present invention.
Specifically, the present invention is as follows.

[1] A dyeing method for cellulose fibers or a fiber product containing cellulose fibers, the method comprising the steps of:
- feeding water of a first temperature region of 5°C or higher and lower than 30°C or a second temperature region of 30°C or higher and lower than 40°C to a dyeing bath and introducing cellulose fibers or a fiber product containing cellulose fibers thereto, under the proviso that the water-feeding and the introducing are performed in any order,
- raising the temperature from the first temperature region to a second temperature region of 30°C or higher and lower than 40°C and from the second temperature region to a third temperature region of 40°C or higher and lower than 70°C, or alternatively, raising the temperature from the second temperature region to the third temperature region of 40°C or higher and 70°C or lower,
- maintaining a third temperature within the third temperature region for a predetermined period of time,
- introducing a reactive dye at a temperature equal to or higher than the first temperature region; and
- introducing a mixture of an inorganic salt and an alkaline agent in three or more divided portions separately from introducing the reactive dye at a temperature equal to or higher than the second temperature region.
[2] The dyeing method according to [1], further comprising the step of:
maintaining the temperature within the second temperature region for a predetermined period.
[3] The dyeing method according to [1], wherein all of the divided portions of the mixture of an inorganic salt and an alkaline agent are introduced in the third temperature region.
[4] The dyeing method according to [2], wherein all of the divided portions of the mixture of an inorganic salt and an alkaline agent are introduced in the second temperature region.
[5] The dyeing method according to any one of [1] to [4], wherein the introduction of the divided portions is performed 3 times or more and 5 times or fewer, and when a total amount of the mixture of an inorganic salt and an alkaline agent is T(g), an amount of introduction in a first stage is A(g), and an amount of introduction in a second stage is B(g), the following formulas (1) to (3) are satisfied: $1 / 20 \times T \leq A \leq 5 / 20 \times T$ $1 / 20 \times T \leq B \leq 7 / 20 \times T$ $A \leq B$
[6] The dyeing method according to any one of [1] to [5], wherein a total time period from the water-feeding to completion of the step of maintaining a third temperature is 100 minutes or less.
[7] The dyeing method according to [6], wherein the total time period is 80 minutes or less.
[8] The dyeing method according to any one of [1] to [7], wherein a dyeing reaction time period from a final stage of the introduction of the divided portions to completion of the step of maintaining a third temperature is 20 minutes or longer and 50 minutes or less.
[9] The dyeing method according to [8], wherein the dyeing reaction time period is 40 minutes or longer.
[10] The dyeing method according to any one of [1] to [9], wherein the third temperature is maintained at 60°C or lower.
[11] The dyeing method according to any one of [1] to [10], wherein a time interval of the introduction of the divided portions is 5 minutes to 17 minutes.

[Advantageous Effects of Invention]

According to the dyeing method of the present invention, since the dyeing time is significantly shortened as compared to the exhaust dyeing method of the prior art, in which the special dedicated equipment described above is not used, energy consumption such as power consumption and steam consumption is reduced, whereby CO₂ emissions are significantly reduced. The dyeing method of the present invention is economically effective as compared to the exhaust dyeing method of the prior art, in which the special dedicated equipment described above is used, as it simplifies the dyeing operation without the need for associated capital investment, and uniformly dyed products with comparable high fastness can be obtained. Specifically, the dyeing method of the present invention is a novel dyeing method for cellulose fiber fabric with which the dyeing time is shortened, whereby it is possible to reduce CO₂ emissions, simplify the dyeing operation, and obtain uniformly dyed products with high color fastness and no color unevenness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a jet dyeing machine which can be used in the dyeing method of the present invention.
FIG. 2 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Examples 1 to 4.
FIG. 3 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 5.
FIG. 4 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 6.
FIG. 5 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 7.
FIG. 6 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Examples 8 and 9.
FIG. 7 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Examples 10 to 12.
FIG. 8 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 13.
FIG. 9 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 14.
FIG. 10 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Example 15.
FIG. 11 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 1.
FIG. 12 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 2.
FIG. 13 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 3.
FIG. 14 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 4.
FIG. 15 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 5.
FIG. 16 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 6.
FIG. 17 shows a table of the introduction timing and elapsed time, and a graph showing the relationship between time and temperature of Comparative Example 7.

DESCRIPTION OF EMBODIMENTS

The 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 containing cellulose fibers, the method comprising the steps of:

feeding water of a first temperature region of 5°C or higher and lower than 30°C or a second temperature region of 30°C or higher and lower than 40°C to a dyeing bath and introducing cellulose fibers or a fiber product containing cellulose fibers thereto, under the proviso that the water-feeding and the introducing are performed in any order,
raising the temperature from the first temperature region to a second temperature region of 30°C or higher and lower than 40°C and from the second temperature region to a third temperature region of 40°C or higher and lower than 70°C, or alternatively, raising the temperature from the second temperature region to the third temperature region of 40°C or higher and 70°C or lower,
maintaining a third temperature within the third temperature region for a predetermined period of time,
introducing a reactive dye at a temperature equal to or higher than the first temperature region; and
introducing a mixture of an inorganic salt and an alkaline agent in three or more divided portions separately from introducing the reactive dye at a temperature equal to or higher than the second temperature region. The number of divided portions to be introduced is preferably 5 or fewer.

The form of cellulose fibers or fiber product containing 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, knitted fabric, non-woven fabric, and garment products can be adopted. The cellulose fibers are not particularly limited, examples thereof include cotton, linen, rayon, cuprammonium rayon, lyocell, regenerated cellulose fibers obtained by organic solvent spinning methods, and regenerated cellulose fibers obtained by ionic liquid spinning methods, but cotton, rayon, cuprammonium rayon, lyocell, and regenerated cellulose fibers obtained by organic solvent spinning methods are preferable, and cotton and rayon are more preferable. Fibers other than cellulose fibers of a fiber product containing cellulose fibers to be dyed by the dyeing method of the present embodiment can be dyed in combination with a known dyeing method.
The equipment used in the dyeing method of the present embodiment is not particularly limited. A cheese dyeing machine, a hank 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, or a paddle dyeing machine is preferable, a cheese dyeing machine, a hank dyeing machine, a jet dyeing machine, a beam dyeing machine, a jigger dyeing machine, or a wince dyeing machine is more preferable, a cheese dyeing machine, a hank dyeing machine, a jet dyeing machine, or a winch dyeing machine is more preferable, and a jet dyeing machine is most preferable. FIG. 1 shows an overview of a jet dyeing machine. The dyeing equipment preferably has a temperature raising or temperature adjustment device, a stirring device, and a reserve tank 2 which has a function which enables the preparation and storage of the mixture (solution) of the inorganic salt and alkaline agent in advance and which enables the introduction of divided portions into the dyeing bath of the dyeing equipment, and which stores the solution containing both the inorganic salt and the alkaline agent. When the liquid jet dyeing machine 1 illustrated in FIG. 1 is used, the dyeing reaction can be carried out efficiently by introducing (adding) the solution containing both the inorganic salt and the alkaline agent in the reserve tank 2 to the dyeing liquid via the nozzle 4 while adjusting the temperature of the dyeing bath 6 by means of the heat exchanger 3 and moving the fabric 5. Note that by preparing a solution in which a reactive dye is dissolved in the reserve tank and introducing this into the dyeing device, then preparing a solution in which a mixture (solution) of an inorganic salt and an alkaline agent is dissolved and introducing this into the dyeing device, and then preparing a solution in which a mixture (solution) of an inorganic salt and an alkaline agent is dissolved and introducing this into the dyeing device, the mixture of an inorganic salt and an alkaline agent can be introduced into the dyeing device in three or more divided portions, separately from the step of introducing the reactive dye. The number of divided portions to be introduced is preferably 5 or fewer.
The dyeing method of the present embodiment comprises a step of feeding water of a first temperature region of 5°C or higher and lower than 30°C or a second temperature region of 30°C or higher and lower than 40°C to the dyeing bath and introducing the cellulose fibers or fiber product containing cellulose fibers thereto. Note that the water-feeding and the introducing are performed in any order.
The first temperature region is preferably an environmental temperature of 5°C or higher and lower than 30°C. If the temperature is lower than 5°C, the amount of energy consumed to raise the temperature will be large, resulting in a large amount of CO₂ emissions.
The dyeing method of the present embodiment includes a step of raising the temperature from the first temperature region to a second temperature region of 30°C or higher and lower than 40°C and from the second temperature region to a third temperature region of 40°C or higher and lower than 70°C, or alternatively, raising the temperature from the second temperature region to the third temperature region of 40°C or higher and 70°C or lower.
The second temperature region is preferably 30°C or higher and lower than 40°C. If the temperature is lower than 30°C, the reaction rate of the reactive dye will decrease, whereby it may be difficult to obtain the desired color density or the fastness may decrease. If the temperature is 40°C or higher, the amount of energy consumed to raise the temperature increases, whereby the CO₂ emissions increase accordingly.
The third temperature region is preferably 40°C or higher and 70°C or lower, and more preferably 40°C or higher and 60°C or lower. If the temperature is lower than 40°C, the reaction rate of the reactive dye decreases, whereby it may be difficult to obtain the desired color density or the fastness may decrease. If the temperature is higher than 70°C, the energy consumption required to raise the temperature increases, whereby the CO₂ emissions increase accordingly.
The dyeing method of the present embodiment comprises a step of maintaining the third temperature within the third temperature region for a predetermined period of time.
The time for the step of maintaining the third temperature within the third temperature region is preferably 10 minutes or longer and 70 minutes or less. If the time is less than 10 minutes, the reaction rate of the reactive dye decreases, whereby it may be difficult to obtain the desired color density or the fastness may decrease. If the time exceeds 70 minutes, the energy consumption such as the power required for operating the equipment and the amount of steam required to maintain the temperature of the dyeing bath increases, whereby the CO₂ emissions increase accordingly.
The dyeing method of the present embodiment may further comprise a step of maintaining the temperature within the second temperature region for a predetermined period of time. The time for the step of maintaining the second temperature within the second temperature region is preferably 10 minutes or longer and 70 minutes or less.
The temperature raising rate in the step of raising the temperature from the first temperature region to the second temperature region and from the second temperature region to the third temperature region is not particularly limited, and is preferably 1°C/min or more and 4°C/min or less, and more preferably 1°C/min or more and 2°C/min or less.
The dyeing method of the present embodiment comprises a step of introducing the reactive dye at a temperature equal to or higher than the first temperature region. However, the introduction of the mixture of the inorganic salt and the alkaline agent is started after the introduction of the reactive dye is started.
The dyeing method of the present embodiment comprises a step of introducing the mixture of the inorganic salt and the alkaline agent in three or more divided portions, separately from the step of introducing the reactive dye, at a temperature equal to or higher than the second temperature region. The number of divided portions to be introduced is preferably five or fewer. If the inorganic salt and alkaline agent are introduced without being mixed, each introduction takes time, and energy consumption such as the power required to operate the equipment and the amount of steam required to maintain the temperature of the dyeing bath increases, whereby the CO₂ emissions increase accordingly. If the inorganic salt and alkaline agent are introduced in one portion, not in divided portions, the reactive dye is instantly adsorbed by the cellulose fibers, whereby the obtained dyed product will have strong color unevenness, and the color fastness cannot be evaluated.
If the number of divided portions to be introduced is six or more, a long period of time is required, which increases the amount of energy consumed such as the electricity required to operate the equipment and the amount of steam required to maintain the temperature of the dyeing bath, whereby the CO₂ emissions increase accordingly.
It is preferable that all of the divided portions of the mixture of the inorganic salt and the alkaline agent be introduced in the third temperature region, or that all of the divided portions of the mixture of the inorganic salt and the alkaline agent be introduced in the second temperature region.
The introduction of the divided portions may be performed during the temperature raising step described above, but it will be necessary in such a case to perform the temperature raising operations and the introduction operations in parallel. Therefore, from the viewpoint of suppressing color unevenness, it is preferable that the introduction of all of the divided portions end in the second or third temperature region where the temperature is maintained within the predetermined range. Note that from the viewpoint of dyeing reaction control and workability, the time interval of the introduction of divided portions is preferably 5 minutes to 17 minutes, more preferably 7 minutes to 15 minutes, and further preferably 8 minutes to 12 minutes.
The dyeing reaction time period from the final stage of the introduction of divided portions to the end of the third temperature maintaining step is preferably 20 minutes or longer and 50 minutes or less, and more preferably 40 minutes or longer and 50 minutes or less. If this time is less than 20 minutes, the reaction rate of the reactive dye decreases, whereby it may be difficult to obtain the desired color density or the fastness may decrease. If this time exceeds 50 minutes, the energy consumption such as the power required to operate the equipment and the amount of steam required to maintain the temperature of the dyeing bath increases, whereby the CO₂ emissions increase accordingly.
Though the ratio of division is not particularly limited, it is preferable that the introduction of divided portions be performed 3 times or more and 5 times or fewer, and when the total amount of the mixture of the inorganic salt and the alkaline agent is defined as T(g), the amount of introduction at the first stage is defined as A(g), and the amount of introduction at the second stage is defined as B(g), it is preferable that the following formulas (1) to (3) be satisfied: $1 / 20 \times T \leq A \leq 5 / 20 \times T$ $1 / 20 \times T \leq B \leq 7 / 20 \times T$ $A \leq B$
When the formulas (1) to (3) are not satisfied, color unevenness may occur, whereby it may be difficult to obtain a uniformly dyed product, and color fastness may decrease.
In the dyeing method of the present embodiment, the total time interval from the feeding of water to the end of the third temperature maintaining step is preferably 100 minutes or less, and more preferably 80 minutes or less.
In the dyeing method of the present embodiment, it is preferable to set the rotation speed of a knitted fabric to 30 seconds/cycle to 180 seconds/cycle from the viewpoint of suppressing dyeing unevenness and suppressing surface quality reduction.
The dyeing liquid (solution) in the dyeing bath used in the dyeing method of the present embodiment can comprise one or more reactive dyes, and optionally components such as a dispersant, a wetting agent, a bath softener, a bath leveling agent, and an emulsifier. Examples of reactive dyes include a reactive dye having a functional group that reacts with at least one cellulose fiber, such as monochlorotriazinyl, monofluorotriazinyl, fluorochloropyrimidinyl, dichloroquinoxanyl, vinylsulfonyl, sulfatoethylsulfonyl, or polyfunctional dyes having a plurality of these functional groups, and are dyes which react with the cellulose fiber at a temperature of 20°C or higher and 100°C or lower and at a pH of 8 or higher and 13 or lower. The dye introduction step of introducing the reactive dye is preferably performed before the introduction of the divided portions of the mixture of the inorganic salt and the alkaline agent.
Examples of the inorganic salt used in the dyeing method of the present embodiment 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 introduction amounts of the inorganic salt and the alkaline agent is determined in accordance with the weight of the product to be dyed, the color density, and the bath ratio (weight of the product to be dyed: weight of the dyeing liquid (calculated assuming a specific gravity of 1)). The total introduction amount of the inorganic salt (g/L (dyeing liquid)) is conventionally 1 to 200 g/L, preferably 1 to 100 g/L, and more preferably 1 to 80 g/L. The total introduction amount (g/L) of the alkaline agent is conventionally 0.1 to 50 g/L, and preferably 1 to 20 g/L.
The bath ratio is conventionally 1:1 to 1:100, and is preferably 1:5 to 1:30.
The dyeing method of the present embodiment is completed with the completion of the third temperature maintaining step, and after the dyeing liquid is discharged from the dyeing bath, a washing step is then performed to remove the remaining dye. Though the washing operation may be carried out by any known method, washing can be performed by an arbitrary combination of at least one water washing step for 5 minutes or more at a bath ratio of 1:5 or more at a temperature of 10°C or higher and 40°C or lower and at least one hot water washing step for 5 minutes or more at a bath ratio of 1:5 or more and a temperature of 60°C or higher.

EXAMPLES

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

(1) Calculation of CO₂ Emission Reduction Amount

The power consumption and steam consumption required for the operation of the dyeing machine were measured and CO₂ emission (kg-CO₂e) was calculated 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 the CO₂ intensity 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 in the above-mentioned 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, may be 0.1542 (kg-CO₂e/MJ), and the intensity of steam, β, may be 0.0600 (kg-CO₂e/MJ). In the following Examples and Comparative Examples, the CO₂ emission (kg-CO₂e) was calculated using the intensity of α = 0.1542 (kg-CO₂e/MJ) and β = 0.0600 (kg-CO₂e/MJ). If the CO₂ emission amount was less than 30 (kg-CO₂e), it was determined that the CO₂ emission amount had been reduced, and if it was 30 (kg-CO₂e) or more, it was determined that the CO₂ emission amount had not been reduced.

(2) Color Unevenness (Spotting)

For five randomly selected locations of the dyed fiber product, the color was measured using a spectrophotometer (model: Color-Eye 7000A manufactured by GretagMacbeth LLC) under the conditions of a D56 light source and a viewing angle of 10 degrees, and the L* value, a* value, and b* value in the CIE1976L*a*b* color space were determined. Next, for all 10 combinations obtained by selecting two locations from the five color-measured locations, the ΔL* value, Δa* value, and Δb* value, which are the differences between the L* values, a* values, and b* values of the two selected locations were determined, and the ΔE value of each sample was calculated using the following formula: $ΔE = {({(ΔL *)}^{\land} 2 + {(Δa *)}^{\land} 2 + {(Δb *)}^{\land} 2)}^{\land} 1 / 2$ and the maximum ΔE value was calculated from the 10 ΔE values. If the maximum ΔE value was 1.5 or more, it was determined that there was color unevenness, and if it was less than 1.5, it was determined that there was no color unevenness.

(3) Color Sweat Fastness

A sweat fastness test was conducted in accordance with the sweat fastness test method for the sweat specified in JIS L 0848, and a grade of 4 or higher was judged as "good", a grade of less than 4 was judged as "poor", and if the dyed fiber product had color unevenness (spotting), it was judged as "could not be evaluated." A multi-fiber co-woven fabric, in which eight types of fibers (cotton, nylon, acetate, wool, rayon, acrylic, silk, and polyester) were woven in a vertical stripe pattern, in accordance with JIS L 0803 was used as the standard adjacent fabric.

[Example 1]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced. Next, as the first stage of the divided introduction step, a solution in which 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the first stage introduction, as the second stage of the divided introduction step, a solution in which 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the second stage introduction, as the third stage of the divided introduction step, a solution in which 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the third stage introduction, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 10 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 2, and the evaluation results are shown in Table 1 below.

[Example 2]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, and the introduction amount in the third stage was 16/20 of 5 parts of anhydrous sodium sulfate and 16/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 2, and the evaluation results are shown in Table 1 below.

[Example 3]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 7/20 of 5 parts of anhydrous sodium sulfate and 7/20 of 1.5 parts of sodium carbonate, and the introduction amount in the third stage was 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 2, and the evaluation results are shown in Table 1 below.

[Example 4]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 7/20 of 5 parts of anhydrous sodium sulfate and 7/20 of 1.5 parts of sodium carbonate, and the introduction amount in the third stage was 8/20 of 5 parts of anhydrous sodium sulfate and 8/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 2, and the evaluation results are shown in Table 1 below.

[Example 5]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced, and the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 20 minutes. Next, as the first stage of the divided introduction step, a solution in which 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the first stage introduction, as the second stage of the divided introduction step, a solution in which 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the second stage introduction, as the third stage of the divided introduction step, a solution in which 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. After dyeing at 60°C for 20 minutes from the start of the third stage introduction, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 3, and the evaluation results are shown in Table 1 below.

[Example 6]

The dyeing was performed in the same manner as in Example 5, except that dyeing was performed at 60°C for 30 minutes from the start of the third stage of the divided introduction step, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 4, and the evaluation results are shown in Table 1 below.

[Example 7]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced, and the liquid temperature was raised by heating to 50°C, which is the third temperature region, over 10 minutes. Next, as the first stage of the divided introduction step, a solution in which 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the first stage introduction, as the second stage of the divided introduction step, a solution in which 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. 10 minutes after the start of the second stage introduction, as the third stage of the divided introduction step, a solution in which 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 10 minutes. After dyeing at 50°C for 50 minutes from the start of the third stage introduction, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 5, and the evaluation results are shown in Table 1 below.

[Example 8]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate, and the introduction amount in a fourth stage was 8/20 of 5 parts of anhydrous sodium sulfate and 8/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 6, and the evaluation results are shown in Table 1 below.

[Example 9]

Dyeing was performed in the same manner as in Example 8, except that in the divided introduction step, the introduction amount in the first stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, and the introduction amount in the fourth stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 6, and the evaluation results are shown in Table 2 below.

[Example 10]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, the introduction amount in the fourth stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, and the introduction amount in the fifth stage was 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 7, and the evaluation results are shown in Table 2 below.

[Example 11]

Dyeing was performed in the same manner as in Example 10, except that in the divided introduction step, the introduction amount in the first stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, the introduction amount in the fourth stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, and the introduction amount in the fifth stage was 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 7, and the evaluation results are shown in Table 2 below.

[Example 12]

Dyeing was performed in the same manner as in Example 10, except that in the divided introduction step, the introduction amount in the first stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, the introduction amount in the fourth stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, and the introduction amount in the fifth stage was 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 7, and the evaluation results are shown in Table 2 below.

[Example 13]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced. Next, as the first stage of the divided introduction step, a solution in which 2/20 of 5 parts of anhydrous sodium sulfate and 2/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 17 minutes. 17 minutes after the start of the first stage introduction, as the second stage of the divided introduction step, a solution in which 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 17 minutes. 17 minutes after the start of the second stage introduction, as the third stage of the divided introduction step, a solution in which 12/20 of 5 parts of anhydrous sodium sulfate and 12/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 17 minutes. 17 minutes after the start of the third stage introduction, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 10 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 8, and the evaluation results are shown in Table 2 below.

[Example 14]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced. Next, as the first stage of the divided introduction step, a solution in which 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 5 minutes. 5 minutes after the start of the first stage introduction, as the second stage of the divided introduction step, a solution in which 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 5 minutes. 5 minutes after the start of the second stage introduction, as the third stage of the divided introduction step, a solution in which 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 5 minutes. 5 minutes after the start of the third stage introduction, as a fourth stage of the divided introduction step, a solution in which 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 5 minutes. 5 minutes after the start of the fourth stage introduction, as the fifth stage of the divided introduction step, a solution in which 4/20 of 5 parts of anhydrous sodium sulfate and 4/20 of 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced within 5 minutes. 5 minutes after the start of the fifth stage introduction, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 10 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 9, and the evaluation results are shown in Table 2 below.

[Example 15]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the second stage was 1/20 of 5 parts of anhydrous sodium sulfate and 1/20 of 1.5 parts of sodium carbonate, the introduction amount in the third stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, the introduction amount in the fourth stage was 3/20 of 5 parts of anhydrous sodium sulfate and 3/20 of 1.5 parts of sodium carbonate, the introduction amount in the fifth stage was 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate, and the introduction amount in the sixth stage was 6/20 of 5 parts of anhydrous sodium sulfate and 6/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of introduction timing, elapsed time, CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature are shown in FIG. 10, and the evaluation results are shown in Table 2 below.

[Comparative Example 1]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced. Next, as the first stage of a salt introduction step, 2/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 5 minutes. 5 minutes after the start of the first stage introduction, as the second stage of the salt introduction step, 6/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 5 minutes. 5 minutes after the start of the second stage introduction, as the third stage of the salt introduction step, 12/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 5 minutes. Next, 5 minutes after the third stage of the salt introduction step, as the first stage of an alkaline agent introduction step, 2/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 5 minutes. 5 minutes after the start of the first stage introduction, as the second stage of the alkaline agent introduction step, 6/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 5 minutes. 5 minutes after the start of the second stage introduction, as the third stage of the alkaline agent introduction step, 12/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 5 minutes. 5 minutes after the start of the alkaline agent introduction, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 10 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 11, and the evaluation results are shown in Table 3 below.

[Comparative Example 2]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced. Next, a solution in which 5 parts of anhydrous sodium sulfate and 1.5 parts of sodium carbonate which were dissolved in advance were mixed and was introduced all at once without dividing the solution. 30 minutes after the introduction of the mixed solution of anhydrous sodium sulfate and sodium carbonate, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 10 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 12, and the evaluation results are shown in Table 3 below.

[Comparative Example 3]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which was dissolved in advance, was introduced, and the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 20 minutes. Next, as the first stage of a salt divided introduction step, 2/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 10 minutes. 10 minutes after the start of the first stage introduction, as the second stage of the salt introduction step, 6/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 10 minutes. 10 minutes after the start of the second stage introduction, as the third stage of the salt introduction step, 12/20 of 5 parts of anhydrous sodium sulfate which was dissolved in advance was introduced within 10 minutes. Next, 30 minutes after the third stage of the salt introduction step, as the first stage of an alkaline agent introduction step, 2/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 10 minutes. 10 minutes after the start of the first stage introduction, as the second stage of the alkaline agent introduction step, 6/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 10 minutes. 10 minutes after the start of the second stage introduction, as the third stage of the alkaline agent introduction step, 12/20 of 5 parts of sodium carbonate which was dissolved in advance was introduced within 10 minutes. After dyeing at 60°C for 70 minutes from the start of the third stage alkaline agent introduction, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 13, and the evaluation results are shown in Table 3 below.

[Comparative Example 4]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which had been dissolved in advance, was introduced. Next, a solution in which 5 parts of anhydrous sodium sulfate and 1.5 parts of sodium carbonate dissolved in advance were mixed was introduced all at once without dividing the solution. Immediately after introducing the mixed solution of anhydrous sodium sulfate and sodium carbonate, the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 20 minutes, and dyeing was performed at 60°C for 30 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 14, and the evaluation results are shown in Table 3 below.

[Comparative Example 5]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, thereafter, the liquid temperature was set to 40°C, which is the third temperature region, and as a dye introduction step, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which had been dissolved in advance, was introduced. Next, 5 parts of anhydrous sodium sulfate and 1.5 parts of sodium carbonate which were dissolved in advance were introduced over a period of 30 minutes using dedicated equipment for adding chemicals into a dyeing bath, which is capable of measuring in real time, at a linear speed of 1/30 parts per minute. After the completion of introduction, dyeing was carried out at a liquid temperature of 40°C for 90 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 15, and the evaluation results are shown in Table 3 below.

[Comparative Example 6]

100 parts of water at 20°C, which is the first temperature region, were fed to the liquid jet dyeing machine, 5 parts of knitted fabric composed of unmercerized cotton were then introduced, the rotation speed of the knitted fabric was adjusted to 90 seconds/cycle, 0.26 parts of a reactive dye Procion Red H-E3B manufactured by DyStar, which had been dissolved in advance, was introduced, and the liquid temperature was raised by heating to 60°C, which is the third temperature region, over 2.5 minutes. Next, 5 parts of anhydrous sodium sulfate and 1.5 parts of sodium carbonate which were dissolved in advance were introduced over a period of 15 minutes using dedicated equipment for adding chemicals into a dyeing bath, which is capable of measuring in real time, at a linear speed of 1/15 parts per minute. After the completion of introduction, dyeing was carried out at a liquid temperature of 60°C for 20 minutes, after which the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 16, and the evaluation results are shown in Table 3 below.

[Comparative Example 7]

Dyeing was performed in the same manner as in Example 1, except that in the divided introduction step, the introduction amount in the first stage was 5/20 of 5 parts of anhydrous sodium sulfate and 5/20 of 1.5 parts of sodium carbonate, and the introduction amount in the second stage was 15/20 of 5 parts of anhydrous sodium sulfate and 15/20 of 1.5 parts of sodium carbonate, and thereafter, the dyeing liquid was discharged, and washing operation was then performed by a known method, followed by drying to obtain a dyed product. A table of the introduction timing, elapsed time, and CO₂ emissions (kg-CO₂e), as well as a graph showing the relationship between time and temperature, are shown in FIG. 17, and the evaluation results are shown in Table 3 below.
Calculation of the CO₂ emissions reduction, evaluation of color unevenness, and evaluation of color fastness were performed for the dyed products obtained in Examples 1 to 15 and Comparative Examples 1 to 7. The evaluation results are shown in Tables 1 to 3 below.
In Examples 1 to 15, the CO₂ emissions were significantly reduced, and the resulting dyed products were uniformly dyed without color unevenness, and furthermore had high fastness.
In the dyeing method of Comparative Example 1, in which only the time was reduced and the salt and alkali were introduced separately without mixing, and the dyeing method of Comparative Examples 2 and 4, in which only the time was reduced and the salt and alkali were introduced all at once without divided introduction, though the CO₂ emissions were significantly reduced, strong color unevenness occurred in the resulting dyed product, and as a result, the color fastness could not be evaluated.
In the dyeing method of Comparative Example 3, though the obtained dyed product was uniformly dyed without color unevenness and had high fastness, the dyeing took a significant time, resulting in a large amount of CO₂ emissions.
In the dyeing method of Comparative Example 5, though the resulting dyed product was dyed uniformly without color unevenness and had high fastness, the dyeing took a significant time, resulting in a large amount of CO₂ emissions. Furthermore, the number of divided portions in the mixed divided introduction step was very large (30 divided portions), which is impossible to manually carry out, and dedicated equipment for adding chemicals to the dyeing bath, which is capable of measuring in real time, at a linear speed of 1/30 parts per minute, was required, which is less versatile.
In the dyeing method of Comparative Example 6, though the CO₂ emissions were significantly reduced, strong color unevenness occurred in the resulting dyed product, and accordingly, the color fastness could not be evaluated. Furthermore, the number of divided portions in the mixed divided introduction step was very large (30 divided portions), which is impossible to manually carry out, and dedicated equipment for adding chemicals to the dyeing bath, which is capable of measuring in real time, at a linear speed of 1/30 parts per minute, was required, which is less versatile.
In the dyeing method of Comparative Example 7, in which the time was reduced by limiting the number of divided portions in the mixed divided introduction to two, though the CO₂ emissions were significantly reduced, the resulting dyed product had strong color unevenness, and as a result, the color fastness could not be evaluated.

[Industrial Applicability]

According to the present invention, it is possible to provide a novel dyeing method which reduces CO₂ emissions by shortening the dyeing time and is effective in simplifying dyeing operations, and with which uniformly dyed products with high fastness can be obtained, and thus, the present invention can be suitably applied in the dyeing of fiber products containing cellulose fibers.

[Reference Signs List]

1: jet dyeing machine
2: reserve tank
3: heat exchanger
4: nozzle
5: fabric
6: dyeing bath

Claims

A dyeing method for cellulose fibers or a fiber product containing cellulose fibers, the method comprising the steps of:
feeding water of a first temperature region of 5°C or higher and lower than 30°C or a second temperature region of 30°C or higher and lower than 40°C to a dyeing bath and introducing cellulose fibers or a fiber product containing cellulose fibers thereto, under the proviso that the water-feeding and the introducing are performed in any order,

raising the temperature from the first temperature region to a second temperature region of 30°C or higher and lower than 40°C and from the second temperature region to a third temperature region of 40°C or higher and lower than 70°C, or alternatively, raising the temperature from the second temperature region to the third temperature region of 40°C or higher and 70°C or lower,

maintaining a third temperature within the third temperature region for a predetermined period of time,

introducing a reactive dye at a temperature equal to or higher than the first temperature region; and

introducing a mixture of an inorganic salt and an alkaline agent in three or more divided portions separately from introducing the reactive dye at a temperature equal to or higher than the second temperature region.
The dyeing method according to claim 1, further comprising the step of:
maintaining the temperature within the second temperature region for a predetermined period.
The dyeing method according to claim 1, wherein all of the divided portions of the mixture of an inorganic salt and an alkaline agent are introduced in the third temperature region.
The dyeing method according to claim 1, wherein all of the divided portions of the mixture of an inorganic salt and an alkaline agent are introduced in the second temperature region.
The dyeing method according to claim 1 or 2, wherein the introduction of the divided portions is performed 3 times or more and 5 times or fewer, and when a total amount of the mixture of an inorganic salt and an alkaline agent is T(g), an amount of introduction in a first stage is A(g), and an amount of introduction in a second stage is B(g), the following formulas (1) to (3) are satisfied: $1 / 20 \times T \leq A \leq 5 / 20 \times T$ $1 / 20 \times T \leq B \leq 7 / 20 \times T$ $A \leq B$
The dyeing method according to claim 1 or 2, wherein a total time period from the water-feeding to completion of the step of maintaining a third temperature is 100 minutes or less.
The dyeing method according to claim 6, wherein the total time period is 80 minutes or less.
The dyeing method according to claim 1 or 2, wherein a dyeing reaction time period from a final stage of the introduction of the divided portions to completion of the step of maintaining a third temperature is 20 minutes or longer and 50 minutes or less.
The dyeing method according to claim 8, wherein the dyeing reaction time period is 40 minutes or longer.
The dyeing method according to claim 1 or 2, wherein the third temperature is maintained at 60°C or lower.
The dyeing method according to claim 1 or 2, wherein a time interval of the introduction of divided portions is 5 minutes to 17 minutes.