A method for removing oligomers from the surface of a terylene fiber product

Abstract

The application discloses a method for removing oligomers on the surface of polyester fiber products, which comprises the following steps: adding the polyester fiber products into water, adding 0.1-10 grams of non-ionic surfactant with an HLB value less than 10 per 1 liter of water, draining the water after cleaning the polyester fiber products at 15-60 DEG C for 5-30 minutes, then adding the polyester fiber products into a non-water medium, draining the non-water medium after cleaning the polyester fiber products at 15-50 DEG C for 5-15 minutes, wherein the non-water medium is at least one selected from tetrachloroethylene, n-butyl acetate, gamma-butyrolactone, epsilon-caprolactone and 1,4-dioxane, and taking out the cleaned polyester fiber products and sealingly drying them in a drying machine provided with a condensing recovery device. Experiments prove that the method can effectively remove the oligomers on the surface of the polyester fiber products, and has the advantages of simple operation, easy realization of large scale, recycling of waste liquid, low cost, high efficiency, environmental protection and the like.

Description

Technical Field

[0001] This invention relates to a method for removing oligomers from the surface of polyester fiber products, belonging to the field of chemical treatment technology. Background Technology

[0002] Polyester fiber is the most consumed synthetic fiber in the world today. Its basic component is polyethylene terephthalate (PET). Oligomers are byproducts produced during polyester production from the polycondensation of terephthalic acid and ethylene glycol. They typically include linear oligomers and cyclic trimers. Linear oligomers account for about 25% of polyester oligomers. Due to their polar end groups, they have some solubility in water and are therefore easily removed with minimal impact. Cyclic trimers make up more than 70% of polyester oligomers. Because of their highly symmetrical structure, cyclic trimers readily aggregate and crystallize. The crystals they form have a melting point of 310℃ and exhibit high thermal and chemical stability. When dyed with disperse dyes at 130–135℃, the solubility of cyclic trimers is less than 2 mg / L. Therefore, cyclic trimers are very difficult to remove during polyester dyeing. In addition, during the dyeing process of polyester fiber products, as the dyeing temperature increases and the dyeing time is extended, oligomers will continuously separate from the fiber and migrate to the surface. The oligomers that migrate from the inside of the fiber to the surface will affect the feel and appearance of the polyester fiber, increase the friction of the polyester yarn, and cause a decline in the quality of the polyester yarn. Furthermore, the oligomers deposited on the surface of polyester fiber products will also form quality defects such as color difference, color spots, and color stains.

[0003] To avoid the adverse effects of oligomers on polyester fiber products, traditional methods mainly involve reduction cleaning with sodium hydrosulfite (Na2S2O4) and high-temperature soaping with caustic soda after disperse dyeing. However, this method has poor oligomer removal efficiency and suffers from problems such as long processing time, high energy consumption, and significant environmental pollution. Existing technologies have reported methods for adding oligomer removal auxiliaries during polyester dyeing to prevent oligomer deposition. These oligomer removal agents include resin-based, anionic, nonionic, and cationic types. Resin-based oligomer removal agents have poor alkali resistance and cannot be used in alkaline baths. Furthermore, they can affect the dispersion performance of dyes in acidic dyeing baths, limiting their use in simultaneous dyeing and washing processes. Additionally, anionic and nonionic oligomer removal agents are often used in combination, but their cleaning effect on oligomers is poor. Cationic oligomer removal agents, on the other hand, pose a risk of residue residue on fiber products after washing, affecting the stability of subsequent printing and dyeing processes. In other words, there is currently no effective method for removing oligomers from the surface of polyester fiber products. There is an urgent need in this field for a technology that can remove oligomers from the surface of polyester fiber products at low cost, high efficiency, environmentally friendly and easy to operate. Summary of the Invention

[0004] In view of the above-mentioned problems and needs of the existing technology, the purpose of this invention is to provide a method for removing oligomers from the surface of polyester fiber products that is low-cost, efficient, environmentally friendly and simple to operate.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for removing oligomers from the surface of polyester fiber products includes the following steps:

[0007] a) Add polyester fiber products to water and add 0.1 to 10 grams of nonionic surfactant with an HLB value of less than 10 per liter of water. Wash at 15 to 60°C for 5 to 30 minutes, and then drain the liquid.

[0008] b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium and clean it at 15-50°C for 5-15 minutes, then drain the liquid. The non-aqueous medium is selected from at least one of tetrachloroethylene, n-butyl acetate, γ-butyrolactone, ε-caprolactone and 1,4-dioxane.

[0009] c) Remove the polyester fiber products that have been cleaned in step b) and place them in a dryer equipped with a condensation recovery device for sealed drying.

[0010] In a preferred embodiment, in step a), 1 to 5 grams of nonionic surfactant are added per liter of water.

[0011] In a further preferred embodiment, in step a), the HLB value of the nonionic surfactant is 3 to 7.

[0012] In a further preferred embodiment, in step a), the nonionic surfactant is selected from any one of Span 65, castor oil polyoxyethylene 10 ether, and isopropyl myristate.

[0013] In a preferred embodiment, in step a), the mass ratio of polyester fiber product to water is 1:5 to 1:30, with 1:10 to 1:20 being more preferred.

[0014] In a preferred embodiment, in step b), the mass ratio of polyester fiber product to non-aqueous medium is 1:5 to 1:30, with 1:10 to 1:20 being more preferred.

[0015] In a preferred embodiment, in step c), the drying process refers to sealing and maintaining the temperature at 50–80°C for 30–120 minutes.

[0016] In a preferred embodiment, the liquid discharged in step a) is centrifuged to collect water for reuse.

[0017] In a preferred embodiment, the liquid discharged in step b) is subjected to activated carbon adsorption to collect the non-aqueous medium for reuse.

[0018] In addition, it should be noted that the polyester fiber products described in this invention include polyester yarn, polyester fabric and various polyester fiber products. The method described in this invention can not only be used for the post-dyeing cleaning treatment of polyester yarn and polyester fabric to replace the reduction cleaning and soaping steps in the existing dyeing process, but also for the surface repair treatment of polyester fiber products.

[0019] Compared with the prior art, the present invention has the following significant advantages:

[0020] Experiments have shown that the method described in this invention can not only effectively remove surface oligomers from polyester fiber products, but also is simple to operate, easy to scale up, and the waste liquid can be recycled and reused. It has the advantages of low cost, high efficiency and environmental protection. It is of great significance and application value for solving quality problems such as stains, floating color, color spots and color difference caused by surface oligomers in polyester fiber products. Attached Figure Description

[0021] Figure 1 This is a standard curve used to detect the content of cyclic trimers in a specific implementation. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail and completely below with reference to specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0023] The method for determining the surface oligomer content in this application is as follows:

[0024] Construction of the quantitative standard curve: PET cyclic trimer (Chinese name: ethylene terephthalate cyclic trimer, CAS number 7441-32-9) standard (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) powder was prepared into a 1 g / L stock solution using 1,4-dioxane, and then gradually diluted to five concentrations: 0.02 g / L, 0.04 g / L, 0.08 g / L, 0.10 g / L, and 0.20 g / L. Each standard solution was injected in 5 μL for high-performance liquid chromatography (HPLC) separation, and the peak area corresponding to the cyclic trimer was detected. A curve was constructed showing the relationship between the reference peak area and the cyclic trimer concentration, with the cyclic trimer concentration as the x-axis and the HPLC peak area as the y-axis (see details). Figure 1 As shown), using weighted 1 / X 2 The least squares regression method was used to calculate the linear regression equation between them, which is: y = 4668783.14394x + 17669.64962, and its correlation coefficient is: R0 2=0.9997;

[0025] Preparation of extract: After cutting the test sample into small pieces, weigh 0.5 g and place it in an Erlenmeyer flask. Then add 15 mL of 1,4-dioxane and stir at 25 °C for 25 min to extract the oligomers on the surface of polyester fiber products. After extraction, take 1.5 mL of the extract, filter it through a 0.45 μm organic phase filter, and determine the peak area of ​​the cyclic trimer using high performance liquid chromatography (HPLC). Calculate the content of the cyclic trimer (as a percentage of the test sample mass).

[0026] High-performance liquid chromatography (HPLC) analysis conditions: The stationary column was a Waters C18 column with an inner diameter of 4.6 mm, a column length of 250 mm, and a packing particle size of 5 μm; mobile phase A was acetonitrile, mobile phase B was deionized water, the mobile phase flow rate was 1.0 mL / min, the column temperature was 40℃, the detection wavelength was 239 nm, and the injection volume was 5 μL; the elution program was a combination of gradient elution and isocratic elution. From 0 to 15 min, mobile phase A decreased from 30% to 100% volume, and mobile phase B decreased from 70% to 0% volume; from 15 to 20 min, isocratic elution was used, with the volume ratio of mobile phase A to mobile phase B being 100%:0%; from 20 to 21 min, mobile phase A decreased from 100% to 30% volume, and mobile phase B decreased from 0% to 70% volume.

[0027] The methods for determining the K / S value and the values ​​of L, a, b, and ΔE in this application are as follows:

[0028] Take test samples and select different locations to measure the K / S value, L, a, b, and ΔE values ​​using a Datacolor 800 colorimeter. Use qualified products of the same polyester fiber as standard samples. The color difference ΔE represents the color difference. The smaller the ΔE value, the better. If ΔE < 4.3, it is considered to be within the acceptable range.

[0029] Example 1

[0030] A method for removing oligomers from the surface of polyester fiber products includes the following steps:

[0031] a) Add polyester fiber products (in this embodiment, dyed polyester yarn that has not undergone reduction washing and soaping treatment in the prior art) to water, with a mass ratio of polyester fiber products to water of 1:10, and add 1 gram of nonionic surfactant (Span 65 is used in this embodiment, but castor oil polyoxyethylene 10 ether or isopropyl myristate can also be used) per liter of water. After washing at 60°C for 10 minutes, drain the liquid. The drained liquid can be centrifuged to achieve water recycling and reuse.

[0032] b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium (tetrachloroethylene is used in this embodiment, but any one of n-butyl acetate, γ-butyrolactone, ε-caprolactone and 1,4-dioxane can also be used). The mass ratio of polyester fiber product to non-aqueous medium is 1:20. After cleaning at 30°C for 15 minutes, drain the liquid. The drained liquid can be recycled and reused by adding activated carbon for adsorption.

[0033] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer equipped with a condensation recovery device. Keep them sealed at 50°C for 120 minutes to achieve drying of the cleaned polyester fiber products and recovery of non-aqueous media.

[0034] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0035] Comparative Example 1

[0036] The main difference between this comparative example and Example 1 is that step b) involves washing with water, and the specific steps are as follows:

[0037] a) Add polyester fiber products (dyed polyester yarn that has not undergone reduction cleaning and soaping treatment in the existing technology) to water, with a mass ratio of polyester fiber products to water of 1:10, and add 1 gram of nonionic surfactant (Span 65) per liter of water, wash at 60°C for 10 minutes, and then drain.

[0038] b) Add the polyester fiber products cleaned in step a) to water, with a mass ratio of polyester fiber products to water of 1:20, and clean at 30°C for 15 minutes before draining.

[0039] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer. Keep them sealed at 50°C for 120 minutes to dry the cleaned polyester fiber products.

[0040] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0041] Example 2

[0042] A method for removing oligomers from the surface of polyester fiber products includes the following steps:

[0043] a) Add polyester fiber products (in this embodiment, dyed polyester yarn that has not undergone reduction washing and soaping treatment in the prior art) to water, with a mass ratio of polyester fiber products to water of 1:15, and add 2 grams of nonionic surfactant (isopropyl myristate is used in this embodiment, but Span 65 or castor oil polyoxyethylene 10 ether can also be used) per liter of water, wash at 40°C for 20 minutes, and then drain the liquid. The drained liquid can be centrifuged to achieve water recycling and reuse.

[0044] b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium (γ-butyrolactone is used in this embodiment, but tetrachloroethylene, n-butyl acetate, ε-caprolactone and 1,4-dioxane can also be used). The mass ratio of polyester fiber product to non-aqueous medium is 1:15. After cleaning at 40°C for 10 minutes, drain the liquid. The drained liquid can be recycled and reused by adding activated carbon for adsorption.

[0045] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer equipped with a condensation recovery device. Keep them sealed at 80°C for 60 minutes to achieve drying of the cleaned polyester fiber products and recovery of non-aqueous media.

[0046] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0047] Comparative Example 2

[0048] The main difference between this comparative example and Example 2 is that step b) involves washing with water, as detailed below:

[0049] a) Add polyester fiber products (dyed polyester yarn that has not undergone reduction washing and soaping treatment in the existing technology) to water, with a mass ratio of polyester fiber products to water of 1:15, and add 2 grams of nonionic surfactant (isopropyl myristate) per liter of water, wash at 40°C for 20 minutes and then drain.

[0050] b) Add the polyester fiber products cleaned in step a) to water, with a mass ratio of polyester fiber products to water of 1:15, and clean at 40°C for 10 minutes before draining.

[0051] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer. Keep them sealed at 50°C for 120 minutes to dry the cleaned polyester fiber products.

[0052] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0053] Example 3

[0054] A method for removing oligomers from the surface of polyester fiber products includes the following steps:

[0055] a) Add polyester fiber products (in this embodiment, dyed polyester yarn that has not undergone reduction washing and soaping treatment in the prior art) to water, with a mass ratio of polyester fiber products to water of 1:20, and add 3 grams of nonionic surfactant per liter of water (in this embodiment, castor oil polyoxyethylene 10 ether is used, but Span 65 or isopropyl myristate can also be used), wash at 50°C for 15 minutes, and then drain the liquid. The drained liquid can be centrifuged to achieve water recycling and reuse.

[0056] b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium (1,4-dioxane is used in this embodiment, but any one of tetrachloroethylene, n-butyl acetate, ε-caprolactone and γ-butyrolactone can also be used). The mass ratio of polyester fiber product to non-aqueous medium is 1:10. After cleaning at 30°C for 15 minutes, drain the liquid. The drained liquid can be recycled and reused by adding activated carbon for adsorption.

[0057] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer equipped with a condensation recovery device. Keep them sealed at 60°C for 80 minutes to achieve drying of the cleaned polyester fiber products and recovery of non-aqueous media.

[0058] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0059] Comparative Example 3

[0060] The main difference between this comparative example and Example 3 is that step b) involves washing with water, as detailed below:

[0061] a) Add polyester fiber products (dyed polyester yarn that has not undergone reduction cleaning and soaping treatment in the existing technology) to water, with a mass ratio of polyester fiber products to water of 1:20, and add 3 grams of nonionic surfactant (castor oil polyoxyethylene 10 ether) per liter of water, wash at 50°C for 15 minutes and then drain.

[0062] b) Add the polyester fiber products cleaned in step a) to water, with a mass ratio of polyester fiber products to water of 1:10, and clean at 30°C for 15 minutes before draining.

[0063] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer. Keep them sealed at 50°C for 120 minutes to dry the cleaned polyester fiber products.

[0064] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0065] Example 4

[0066] A method for removing oligomers from the surface of polyester fiber products includes the following steps:

[0067] a) Add polyester fiber products (dyed polyester fabric in this example) to water, with a mass ratio of polyester fiber products to water of 1:15, and add 2 grams of nonionic surfactant per liter of water (isopropyl myristate is used in this example, but Span 65 or castor oil polyoxyethylene 10 ether can also be used). Wash at 50°C for 15 minutes and then drain the liquid. The drained liquid can be centrifuged to achieve water recycling.

[0068] b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium (in this embodiment, ε-caprolactone is used, but tetrachloroethylene, n-butyl acetate, γ-butyrolactone and 1,4-dioxane can also be used). The mass ratio of polyester fiber product to non-aqueous medium is 1:20. After cleaning at 30°C for 15 minutes, drain the liquid. The drained liquid can be recycled and reused by adding activated carbon for adsorption.

[0069] c) Take out the polyester fiber products after cleaning in step b) and put them into a dryer equipped with a condensation recovery device. Keep them sealed at 80°C for 60 minutes to achieve drying of the cleaned polyester fiber products and recovery of non-aqueous media.

[0070] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0071] Comparative Example 4

[0072] The main difference between this comparative example and Example 4 is that the dyed polyester fabric is cleaned using existing technology, and the specific steps are as follows:

[0073] The dyed polyester fabric was added to a cleaning solution containing 5 g / L sodium hydrosulfite and 2 g / L sodium hydroxide, with a polyester fabric to water ratio of 1:10. After cleaning at 60°C for 15 minutes, the solution was drained and then placed in a dryer and kept in a sealed environment at 50°C for 120 minutes to dry the cleaned polyester fiber products.

[0074] For the dried polyester fiber products, the surface oligomer content, K / S value, and L, a, b, and ΔE values ​​were determined according to the above method. The specific test results are shown in Table 1 and Table 2, respectively.

[0075] Table 1. Results of determination of oligomer content on the surface of polyester fiber products

[0076] Test sample Oligomer content (%) Example 1 0.00894 Comparative Example 1 0.21294 Example 2 0.00761 Comparative Example 2 0.17528 Example 3 0.00547 Comparative Example 3 0.21646 Example 4 0.00735 Comparative Example 4 0.19171

[0077] Table 2. Determination results of K / S value, L, a, b and ΔE value of polyester fiber products.

[0078] Test sample K / S value L a b ΔE Example 1 19.526 35.61 50.23 19.61 0.96 Comparative Example 1 19.383 36.81 51.86 20.65 2.22 Example 2 19.841 34.47 49.89 19.87 0.54 Comparative Example 2 19.224 36.41 50.85 19.82 0.98 Example 3 19.485 35.96 50.22 19.98 0.76 Comparative Example 3 19.263 36.51 51.02 18.93 0.96 Example 4 19.632 35.00 50.41 19.66 0.67 Comparative Example 4 18.047 36.93 50.71 18.41 1.49

[0079] As shown in Tables 1 and 2, the method of this invention can significantly reduce the content of surface oligomers in polyester fiber products. Compared with the treatment of nonionic surfactants under the same conditions (such as Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 3 and Comparative Example 3) and the reduction cleaning of sodium hydrosulfite and the soaping treatment of alkali in the prior art (such as Example 4 and Comparative Example 4), it has produced significant progress and unexpected technical effects. In addition, the method of this invention also has the advantages of simple operation, easy to scale up, recycling of waste liquid, low cost, high efficiency and environmental protection. It is of great significance and application value for solving the quality problems of color stains, floating color, color spots and color difference caused by surface oligomers in polyester fiber products.

[0080] In addition, it should be noted that the method described in this invention can also be used for surface repair treatment of polyester fiber products, including clothing and household goods.

[0081] Finally, it should be noted that the above are only some preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for removing oligomers from the surface of polyester fiber products, wherein the oligomers are cyclic trimers; characterized in that, The method includes the following steps: a) Add polyester fiber products to water and add 0.1 to 10 grams of nonionic surfactant with an HLB value of less than 7 per liter of water. Wash at 15 to 60°C for 5 to 30 minutes, and then drain the liquid. b) Add the polyester fiber product cleaned in step a) to a non-aqueous medium and clean it at 15-50°C for 5-15 minutes, then drain the liquid. The non-aqueous medium is selected from at least one of tetrachloroethylene, n-butyl acetate, γ-butyrolactone, ε-caprolactone and 1,4-dioxane. c) Remove the polyester fiber products that have been cleaned in step b) and place them in a dryer equipped with a condensation recovery device for sealed drying.

2. The method according to claim 1, characterized in that: In step a), add 1 to 5 grams of nonionic surfactant per liter of water.

3. The method according to claim 1, characterized in that: In step a), the nonionic surfactant is selected from any one of Span 65, castor oil polyoxyethylene 10 ether, and isopropyl myristate.

4. The method according to claim 1, characterized in that: In step a), the mass ratio of polyester fiber products to water is 1:5 to 1:

30.

5. The method according to claim 1, characterized in that: In step b), the mass ratio of polyester fiber products to non-aqueous media is 1:5 to 1:

30.

6. The method according to claim 1, characterized in that: In step c), drying refers to keeping the product in a sealed environment at 50–80°C for 30–120 minutes.

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