Method for manufacturing bleached polyester fiber products

Abstract

To provide a method for producing decolorized polyester fiber products.SOLUTION: A production method disclosed herein includes heating a polyester fiber product colored with a dye in a solvent. The solvent includes at least one compound selected from general formulae (1)-(2). The heating temperature is 100°C or higher and 160°C or lower. R1OOC-X-COOR2 (1). Y1-(AO)n-COR4 (2). X is a C2-4 alkylene group or alkenylene group, R1 is a C1-4 alkyl group or phenyl group, R2 is a C1-4 alkyl group or phenyl group, AO is a C2-3 alkyleneoxy group, n is an integer of 1-3, Y1 is a R3O group or R3COO group, R3 is a C1-4 alkyl group or phenyl group, and R4 is a C1-4 alkyl group or phenyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application discloses a method for manufacturing decolorized polyester fiber products. [Background technology]

[0002] Polyester (e.g., polyethylene terephthalate) is widely used as a fiber, film, and resin molded product due to its excellent properties. On the other hand, the effective utilization of polyester waste (fiber waste, film waste, resin waste) and used PET bottles generated during the manufacturing process is a major challenge not only from a cost perspective but also from an environmental perspective. Material recycling and chemical recycling are among the methods being considered and proposed for the effective utilization of polyester waste.

[0003] Regarding the material recycling of polyester waste, for example, active reuse is being carried out targeting waste polyester molded products such as used PET bottles. Furthermore, regarding the chemical recycling of polyester waste, for example, it has been proposed to regenerate polyester waste into raw material monomers, and then to produce new polyester by subjecting these regenerated raw material monomers to another polycondensation reaction (see, for example, Patent Document 1).

[0004] However, it is difficult to perform material recycling or chemical recycling of dyed polyester fibers in their original state. In order to perform material recycling or chemical recycling of dyed polyester fibers, it is important to remove the dye from the polyester fibers (see, for example, Patent Documents 2-4).

[0005] Patent Document 2 discloses the use of heated ethylene glycol as a solvent when extracting coloring components from fibrous polyester.

[0006] Patent Document 3 discloses a method for decolorizing polyester by preparing a decolorizing agent containing a glycol ether compound having a boiling point of 160°C or higher at atmospheric pressure, heating the decolorizing agent to 160-210°C, and bringing the colored polyester into contact with the heated decolorizing agent.

[0007] Patent Document 4 discloses a dye extraction process for dyed polyester fibers, in which an extraction solvent consisting of xylene and alkylene glycol is used to extract and remove the dye at a temperature between the glass transition temperature of polyester and 220°C. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2008-088096 [Patent Document 2] Japanese Patent Publication No. 2005-330444 [Patent Document 3] International Publication No. 2020 / 213032 [Patent Document 4] International Publication No. 2007 / 018161 [Overview of the project] [Problems that the invention aims to solve]

[0009] According to our new findings, when decolorizing polyester fibers colored with dyes, using ethylene glycol as an extraction solvent, as disclosed in Patent Document 2, does not yield a sufficient dye extraction (removal) effect. Furthermore, methods using decolorizing agents containing glycol monoethers with 8 to 15 carbon atoms, as disclosed in Patent Document 3, do not yield a sufficient dye removal effect. In addition, the method disclosed in Patent Document 3 involves high heating temperatures and high CO2 emissions, resulting in a significant environmental burden; therefore, decolorization technology at lower temperatures is desirable. Moreover, xylene, disclosed in Patent Document 4, is designated as a Class I designated chemical substance under the PRTR Law, and its use should be avoided. [Means for solving the problem]

[0010] This application is one means of solving the above problem, A method for manufacturing bleached polyester fiber products, This includes heating polyester fiber products colored with dyes in a solvent, The solvent comprises at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). The heating temperature is 100°C or higher and 160°C or lower. Disclose the following.

[0011] R 1 OOC-X-COOR 2 ...(1) Y 1 -(AO) n -COR 4 ...(2) In general formula (1), X is an alkylene or alkenylene group having 2 to 4 carbon atoms. R 1 This is an alkyl group or phenyl group having 1 to 4 carbon atoms. R 2 This is an alkyl group or phenyl group having 1 to 4 carbon atoms. In general formula (2), AO is an alkyleneoxy group having 2 to 3 carbon atoms, n is an integer of 1 to 3, Y 1 is R 3 O group or R 3 COO group, R 3 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, R 4 is an alkyl group having 1 to 4 carbon atoms or a phenyl group.

Advantages of the Invention

[0012] According to the method of the present disclosure, the dye can be extracted from the polyester fiber product colored with the dye at a low temperature, and the environmental load is also small.

Modes for Carrying Out the Invention

[0013] This application discloses a method for producing a decolorized polyester fiber product. The production method of the present disclosure includes heating a polyester fiber product colored with a dye in a solvent. Here, the solvent contains at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). Further, the temperature of the heating is 100°C or higher and 160°C or lower.

[0014] R 1 OOC-X-COOR 2 ···(1) Y 1 -(AO) n -COR 4 ···(2) In the general formula (1), X is an alkylene group or an alkenylene group having 2 to 4 carbon atoms, R 1 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, R 2 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, In the general formula (2), AO is an alkyleneoxy group having 2 to 3 carbon atoms, n is an integer from 1 to 3. Y 1 is R 3 O group or R 3 It is a COO group, R 3 This is an alkyl group or phenyl group having 1 to 4 carbon atoms. R 4 This is an alkyl group or phenyl group having 1 to 4 carbon atoms.

[0015] 1. Polyester fiber products colored with dyes The manufacturing method disclosed herein produces a decolorized polyester fiber product by removing (decolorizing) the dye from a polyester fiber product that has been colored with a dye. The polyester fiber product that has been colored with a dye may have, for example, the following configuration.

[0016] 1.1 Materials for polyester fiber products The material for polyester fiber products may be anything that contains polyester fibers. The material may consist solely of polyester fibers, or it may consist of polyester fibers and other fibers (blended, twisted, woven, knitted, etc.).

[0017] 1.2 Forms of polyester fiber products There are no particular restrictions on the form of polyester fiber products; they may be in the form of raw materials or semi-finished products such as cotton, yarn, cord, woven fabric, knitted fabric, or nonwoven fabric, or they may be in the form of finished products such as clothing.

[0018] 1.3 Dyes The dye can be any dye commonly used for coloring polyester fibers. For example, the dye may be a disperse dye. There are no particular restrictions on the type of disperse dye; it may be either azo or quinone. Examples of disperse dyes include compounds classified as CI Disperse Black, CI Disperse Blue, CI Disperse Red, CI Disperse Orange, CI Disperse Yellow, CI Disperse Green, CI Disperse Violet, and CI Disperse Brown. There are also no particular restrictions on the amount of dye that adheres to the polyester fibers.

[0019] 2. Solvent In the method disclosed herein, a solvent is used for extracting the dye from a polyester fiber product colored with the dye, which includes at least one compound selected from the group consisting of the compound represented by general formula (1) and the compound represented by general formula (2).

[0020] 2.1 Compounds represented by general formula (1) In the above general formula (1), X is an alkylene group or alkenylene group having 2 to 4 carbon atoms. If X is a group other than these, the polyester fibers are prone to re-contamination by the dye extracted into the solvent. X may be a linear alkylene group or an alkenylene group, or a branched alkylene group or an alkenylene group. If X is an alkenylene group having 2 to 4 carbon atoms, the alkenylene group is preferably a vinylene group, and the compound represented by the above general formula (1) may be a cis or trans isomer.

[0021] In the above general formula (1), R 1 R is an alkyl group or phenyl group having 1 to 4 carbon atoms. 2 R is an alkyl group or phenyl group having 1 to 4 carbon atoms.1 Ya R 2 If the group is anything other than these, the solubility of the dye in the solvent decreases, and the decolorizing effect decreases. From the viewpoint of facilitating washing and removal after decolorization, R 1 R may be an alkyl group having 1 or 2 carbon atoms, 2 R may be an alkyl group having 1 or 2 carbon atoms. 1 and R 2 These elements may be the same group or different groups. 1 and R 2 If the alkyl group is an alkyl group, it may be a linear alkyl group or a branched alkyl group.

[0022] The compound represented by the above general formula (1) has a chemical structure corresponding to a dibasic acid diester. Specific examples of compounds having such a chemical structure include dimethyl succinate, diethyl succinate, dimethyl glutarate, diethyl glutarate, dimethyl adipate, diethyl adipate, diisobutyl adipate, dimethyl 2-methylglutarate, dimethyl maleate, and diethyl maleate. When the compound represented by the above general formula (1) is at least one selected from dimethyl adipate, diisobutyl adipate, dimethyl glutarate, and dimethyl 2-methylglutarate, an even higher decolorizing effect is exhibited.

[0023] 2.2 Compounds represented by general formula (2) In the general formula (2) above, AO is an alkylene oxy group having 2 to 3 carbon atoms. That is, it may be an ethylene oxy group, a propylene oxy group, or a combination thereof. When AO is an alkylene oxy group having 4 or more carbon atoms, polyester fibers are easily re-contaminated by the dye extracted into the solvent.

[0024] In the general formula (2) above, n is an integer between 1 and 3. In particular, the decolorizing effect is more easily achieved when n is small. In this regard, n may also be 1 or 2.

[0025] In the above general formula (2), Y1 is R 3 O group or R 3 It is a COO group, R 3 R is an alkyl group or phenyl group having 1 to 4 carbon atoms. 4 This is an alkyl group or phenyl group having 1 to 4 carbon atoms. 1 , R 3 and R 4 If the group is anything other than these, the solubility of the dye in the solvent decreases, and the decolorizing effect tends to decrease. 3 and R 4 These elements may be the same group or different groups. 3 and / or R 4 If the alkyl group is an alkyl group, it may be a linear alkyl group or a branched alkyl group.

[0026] 2.3 Other Ingredients In the manufacturing method of this disclosure, at least one compound represented by the above general formula (1) or the above general formula (2) is selected and used as a solvent for extracting dye from polyester fiber products. In the manufacturing method of this disclosure, the solvent may consist only of the compounds represented by formulas (1) and (2), or it may contain other components in addition to the compounds said thereon. In the manufacturing method of this disclosure, the content of other components other than the compounds represented by formulas (1) and (2) in the solvent is not particularly limited. In the manufacturing method of this disclosure, a decolorizing effect can be achieved whether the concentration of the compounds of formulas (1) and (2) in the solvent is low or high.

[0027] 3. Decolorization treatment In the manufacturing method of the present disclosure, a polyester fiber product colored with a dye is heated in a solvent, thereby extracting the dye from the polyester fiber into the solvent and decolorizing the polyester fiber.

[0028] 3.1 Heating temperature The heating temperature in the decolorization process is between 100°C and 160°C. For example, the polyester fiber product to be decolorized may be immersed in a solvent and then heated to a temperature between 100°C and 160°C. Alternatively, the polyester fiber product to be decolorized may be immersed in a solvent maintained at a temperature between 100°C and 160°C. If the heating temperature is too low, the solubility of the dye in the solvent will be low, and a sufficient decolorization effect will not be obtained. If the heating temperature is too high, existing equipment may not be able to handle it, and the energy load will be high, and CO2 emissions will tend to be high. These problems are easily resolved if the heating temperature is between 100°C and 160°C. The heating temperature is preferably between 110°C and 150°C, and more preferably between 120°C and 140°C.

[0029] 3.2 Heating time During the decolorization process, the holding time (heating time) after reaching the above-mentioned heating temperature is not particularly limited. Since the degree of decolorization can change depending on the heating time, the heating time should be appropriately determined according to the desired degree of decolorization. If the heating time is too short, the degree of decolorization will be small. If the heating time is too long, there is a risk that the dye extracted from the polyester fiber product into the solvent may reattach to the polyester fiber product, which may worsen the decolorization efficiency. The heating time may be, for example, 10 seconds to 120 minutes. Preferably, it is 10 minutes to 100 minutes.

[0030] 3.3 Bath ratio The bath ratio (mass ratio) of the polyester fiber product to be decolorized to the solvent is not particularly limited, but for example, a ratio of polyester fiber product:solvent of approximately 1:5 to 1:500 may be appropriate. If the bath ratio is too small, it becomes difficult to heat the polyester fiber product in the solvent. On the other hand, if the bath ratio is too large, the decolorization effect will saturate, which is unfavorable in terms of cost.

[0031] 3.4 Equipment The equipment used for decolorization is not particularly limited as long as it can heat polyester fiber products in the solvent mentioned above, but commercially suitable equipment includes jet dyeing machines, cheese dyeing machines, beam dyeing machines, package dyeing machines, and high-pressure jet dyeing machines.

[0032] 4. Other processes The manufacturing method of the present disclosure may include a decolorization treatment by heating using the above-mentioned solvent, and may also include other steps. For example, after the above-mentioned decolorization treatment, the polyester fiber product may be washed to remove the solvent, etc., from the polyester fiber after an optional cooling step, and then dried. For example, the solvent, etc., adhering to the polyester fiber product can be removed by washing the polyester fiber product that has undergone the above-mentioned decolorization treatment with water or by contacting it with a solvent other than those mentioned above.

[0033] 5. Effects As described above, the manufacturing method of this disclosure uses a relatively safe and environmentally friendly compound as a solvent, and the emission of VOCs and harmful substances during the decolorization process is minimal. In this respect, the manufacturing method of this disclosure makes it possible to construct an environmentally conscious upcycling system. Furthermore, the manufacturing method of this disclosure allows for decolorization at low temperatures of 100°C to 160°C, which also contributes to a low environmental impact. Moreover, the solvent used in the manufacturing method of this disclosure does not easily dissolve polyester fibers, resulting in a high yield of polyester fibers after decolorization. [Examples]

[0034] The effects of the technology of this disclosure will be explained in more detail below with reference to examples, but the technology of this disclosure is not limited to the following specific examples.

[0035] 1. Creation of polyester fiber products (dyed polyester products) colored with dyes. Polyester jersey knit (75d, 50g / m) 2The knit was placed in either dyeing bath 1 or 2, with the composition shown in Table 1 below, so that the bath ratio was 1:15. The dyeing bath was heated from 60°C to 130°C at a heating rate of 2°C / min (heating time: 35 minutes), and held at 130°C for 30 minutes. After that, the temperature was lowered to 80°C, and the knit was removed from the dyeing bath. Next, the removed knit was reduced and washed using a reducing washing bath with the composition shown in Table 2 below (80°C, 15 minutes, bath ratio 1:30), then rinsed with water, dehydrated, and dried to obtain a polyester dyed product. Hereinafter, the dyed product obtained with dyeing bath 1 will be referred to as "dyed product 1," and the dyed product obtained with dyeing bath 2 will be referred to as "dyed product 2."

[0036] [Table 1]

[0037] [Table 2]

[0038] 2. Decolorization of polyester dyed materials In a mini color dyeing machine (manufactured by Techsam Giken), 3g of knit material (either dyeing material 1 or 2) and 150g of solvent shown in Table 3 below were placed in the pot (bath ratio 1:50). The temperature was raised from 60°C to 130°C at a heating rate of 2°C / min and held at 130°C for 30 minutes. After cooling, the knit material was removed at 80°C, washed with 150g of acetone at room temperature for 10 minutes, and then air-dried at room temperature for half a day to obtain a decolorized polyester product. Hereafter, the decolorized product obtained with dyeing material 1 will be referred to as "decolorized product 1," and the decolorized product obtained with dyeing material 2 will be referred to as "decolorized product 2."

[0039] 3. Evaluation of decolorization properties The decolorizing properties of the decolorized material were evaluated according to the following criteria.

[0040] <Judgment criteria> (1) L * Measurement of Values Color measurements were performed using a Konica Minolta colorimeter (SPECTROPHOTOMETER [CM-3700A]). ·Measurement method: reflection • Geometry: di:8° de:8° • Specular reflection treatment: SCI ·Measurement diameter: LAV (25.4mm) ·UV condition: 100%Full

[0041] (2) Calculation of decolorization rate The L of dyed material 1 or 2 and the undyed material before dyeing. * The degree of dyeing is determined from the difference in value, and the L of the decolorized material 1 or 2 and the undyed material before dyeing is determined. * From the difference in values, the degree of dyeing (dye residue) in the decolorized material is identified, and the two L values ​​are... * The decolorization rate (%) was calculated based on the difference in values ​​using the following formula. A calculated decolorization rate of 70% or higher indicates good decolorization performance. The results are shown in Table 3 below. For reference, L * along with the value and decolorization rate, b * The values ​​are also listed. Decolorization rate (%) = 100 - 100 × [(L of unstained material) * Value) - (L of decolorized material) * (Value) ÷ [(L of unstained material) * Value) - (L of the dyed material) * value)]

[0042] 4. Evaluation Results Table 3 below shows the evaluation results. Table 4 below shows the L values ​​for the unstained material before staining. * Value and b * The values, and L for stained materials 1 and 2. * Value and b * Show the value.

[0043] [Table 3]

[0044] In Table 3, "NewSolve RPDE" (manufactured by Nikka Chemical Co., Ltd.) is a mixture consisting of 63% by mass of dimethyl glutarate, 24% by mass of dimethyl succinate, and 13% by mass of dimethyl adipate.

[0045] [Table 4]

[0046] The dimethyl adipate used in Examples 1 and 9 is a compound represented by the following general formula (1), where X is a C4 alkylene group, and R 1 and R 2 This corresponds to an alkyl group with 1 carbon atom. The diisobutyl adipate used in Examples 2, 8 and Comparative Example 4 is a compound represented by the following general formula (1), where X is a C4 alkylene group, and R 1 and R 2 This corresponds to an alkyl group with 4 carbon atoms. The dimethyl glutarate used in Examples 3 and 9 is a compound represented by the following general formula (1), where X is a C3 alkylene group, and R 1 and R 2 This corresponds to an alkyl group with 1 carbon atom. The dimethyl 2-methylglutarate used in Example 4 is a compound represented by the following general formula (1), where X is a C4 alkylene group, and R 1 and R 2 This corresponds to an alkyl group with 1 carbon atom. reference The dipropylene glycol dibenzoate used in Example 5 is a compound represented by the following general formula (2), where AO is a C3 alkylene oxy group, n is 2, and Y 1 R 3 It is a COO group, R 3 is a phenyl group, R 4 This corresponds to a group that is a phenyl group. The ethylene glycol diacetate used in Example 6 is a compound represented by the following general formula (2), where AO is a C2 alkylene oxy group, n is 1, and Y 1 R 3 It is a COO group, R 3 is an alkyl group having 1 carbon atom, and R 4 This corresponds to an alkyl group with 1 carbon atom. The butyl diglycol acetate used in Example 7 is a compound represented by the following general formula (2), where AO is a C2 alkylene oxy group, n is 2, and Y 1 R 3 It is an O group, R 3 is an alkyl group having 4 carbon atoms, and R 4 This corresponds to an alkyl group with 1 carbon atom. The dimethyl succinate used in Example 9 is a compound represented by the following general formula (1), where X is a C2 alkylene group, and R 1 and R 2 This corresponds to an alkyl group with 1 carbon atom. The solvents used in Comparative Examples 1-3 and 5 have structures different from those represented by the following general formulas (1) and (2), and correspond to conventional solvents.

[0047] R 1 OOC-X-COOR 2 ...(1) Y 1 -(AO) n -COR 4 ...(2)

[0048] The results shown in Table 3 indicate the following:

[0049] When ethylene glycol or polyoxyethylene (7 mol) lauryl ether was used as the extraction solvent, sufficient dye extraction (removal) could not be obtained (Comparative Examples 1 and 4), and even increasing the heating temperature during decolorization did not sufficiently improve the dye extraction effect (Comparative Example 3). On the other hand, when xylene was used as the extraction solvent, the dye extraction effect was high (Comparative Example 2). However, xylene is a chemical substance designated as a Class 1 designated chemical substance under the PRTR Law, and has a significant impact on human health and the environment.

[0050] In contrast, Examples 1- 4. Reference Example 5, Example 6~When a predetermined extraction solvent such as 9 is used, it can be seen that the dye can be efficiently extracted from the polyester fiber at a low temperature. However, even if diisobutyl adipate is used as the extraction solvent, if the heating temperature during decolorization is too low, a sufficient dye extraction effect cannot be obtained (Comparative Example 4).

[0051] From the above results, it can be seen that if the method satisfies the following requirements (A) to (C), the dye can be efficiently extracted and decolorized at a low temperature from the polyester fiber product colored with the dye.

[0052] (A) Heating the polyester fiber product colored with the dye in a solvent. (B) The solvent contains at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). (C) The temperature of the heating is 100°C or higher and 160°C or lower.

[0053] R 1 OOC-X-COOR 2 ···(1) Y 1 -(AO) n -COR 4 ···(2) In the general formula (1), X is an alkylene group or an alkenylene group having 2 to 4 carbon atoms, R 1 is an alkyl group or a phenyl group having 1 to 4 carbon atoms, R 2 is an alkyl group or a phenyl group having 1 to 4 carbon atoms, In the general formula (2), AO is an alkyleneoxy group having 2 to 3 carbon atoms, n is an integer of 1 to 3, Y 1 is R 3 O group or R 3 COO group, R 3 is an alkyl group or a phenyl group having 1 to 4 carbon atoms, R4 This is an alkyl group or phenyl group having 1 to 4 carbon atoms.

Claims

1. A method for manufacturing bleached polyester fiber products, This includes heating polyester fiber products colored with dyes in a solvent, The solvent comprises at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). The heating temperature is 100°C or higher and 160°C or lower. Manufacturing method. R １ OOC-X-COOR ２ ・・・(1) Y １ —(AO) ｎ —CO ４ ・・・(2) In general formula (1), X is an alkylene group or alkenylene group having 2 to 4 carbon atoms. R １ is an alkyl group or phenyl group having 1 to 4 carbon atoms. R ２ is an alkyl group or phenyl group having 1 to 4 carbon atoms. In general formula (2), AO is an alkylene oxy group having 2 to 3 carbon atoms. n is an integer between 1 and 3. Y １ is R ３ O group or R ３ COO group, and R ３ These are alkyl groups having 1 to 4 carbon atoms. R ４ These are alkyl groups having 1 to 4 carbon atoms.

2. The bath ratio of the polyester fiber product to the solvent is such that, by mass ratio, the polyester fiber product:solvent = 1:5 to 1:

500. The manufacturing method according to claim 1.

3. The heating temperature is 110°C or higher and 160°C or lower. The manufacturing method according to claim 1 or 2.

4. The heating time is 10 minutes or more and 120 minutes or less. The manufacturing method according to claim 1 or 2.

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