Method for preparing long linen yarn based on combined degumming of photocatalysis and organic acid treatment

Abstract

The invention discloses a method for preparing long hemp yarn based on photocatalysis and organic acid treatment combined degumming, which comprises the following steps: (1) beating hemp bast into hemp, and carding into long hemp bundles; (2) processing the long hemp bundles into hemp strips, drafting, combining, drafting and twisting, and winding to obtain rough hemp yarns; (3) pretreating the hemp roving with a weak acid reagent, taking out, washing with water, and drying; (4) putting the rough hemp yarn into a degumming solution containing a photocatalyst for light treatment, taking out the rough hemp yarn, washing the rough hemp yarn with water, and drying the rough hemp yarn to obtain degummed rough hemp yarn; and (5) drafting the degummed hemp roving, twisting into yarn, drying, and winding the yarn on a bobbin to obtain finished hemp spun yarn, namely the long hemp yarn. According to the method, pectin, lignin and other non-cellulose colloid components in the jute fibers are removed through the combination of the photocatalyst and the organic acid, the degumming condition is mild, the damage effect on the jute fibers is small, the organic acid can be recycled, generated waste liquid is little, and pollution to the environment is small.

Description

Technical Field

[0001] The invention relates to the technical field of textile processing, and in particular to a method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming. Background Art

[0002] Hemp is a natural bast fiber. The cultivation and production of hemp can bring good environmental and economic benefits. It is a high-potential agricultural product. Hemp fiber resources are abundant, with the characteristics of long fiber, high strength, small elongation, fast moisture absorption and release, etc. The spun yarn can be made into various hemp fabrics, hoses, conveyor belts and various sewing hemp threads, etc., for clothing, decoration, industrial and agricultural production and national defense construction. Hemp fiber has a bast fiber structure, which is a single cellulose fibril bonded together by a colloid substance. The colloid substance is mainly composed of hemicellulose, pectin, wax, water-soluble materials and lignin. Since a large amount of colloid substances will increase the toughness and yellowness of hemp fibers, it directly limits their further use. It is very necessary to extract high-quality hemp long fibers from hemp without sacrificing the physical properties or chemical structure of cellulose.

[0003] At present, there are two main methods for preparing long linen yarn: (1) wet spinning method: the coarse yarn is processed through the boiling and bleaching process to swell and remove part of the colloid on the fiber to soften the fiber and reduce the bonding force between the fibers. Then, it is stretched through a water tank (with water, penetrant, softener, etc.) on a wet spinning machine to split and thin the process fibers into finer fiber bundles, which are then twisted into yarn and wound on a bobbin; (2) dry spinning method: the coarse yarn is directly spun on a dry spinning machine to form long linen dry spinning yarn. Of the above two methods, wet spinning yarn has uniform dryness, high strength, less hairiness, and fine spinnable density, while dry spinning cannot effectively remove the colloid on the linen fiber, which affects its use. The boiling and bleaching process in the wet spinning method uses chemical reagents such as caustic soda to react and degrade non-cellulose components such as pectin, hemicellulose and lignin in the linen bast, but this method will produce a lot of pollution and damage cellulose. Compared with traditional alkali degumming, enzyme degumming can significantly reduce pollution emissions, but the role of degumming enzymes is single, which limits the efficiency and effect of degumming and requires the assistance of chemical reagents; organic solvent degumming can recycle the degumming liquid, but the solvent cost is extremely high, and the wastewater also needs further treatment. In addition, the degumming effect of organic solvents is limited, and there is also the problem of incomplete degumming. Therefore, it is urgent to develop a degumming method with mild conditions and low environmental pollution to degumming hemp yarn to obtain long hemp yarn. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming. The method has mild reaction conditions, little environmental pollution, good degumming effect, and less damage to linen fibers.

[0005] The technical solution adopted by the present invention is:

[0006] A method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming, comprising the steps of:

[0007] (1) beating hemp bast into hemp, and after the pre-combing preparation process, combing on a combing machine to obtain parallel and straight long hemp bundles;

[0008] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by 3 to 5 drawing frames to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain flax roving;

[0009] (3) placing the hemp roving into a reactor, adding a weak acid reagent for pretreatment, washing the hemp roving to neutrality after the pretreatment, and drying it;

[0010] (4) adding a photocatalyst into a glass reactor to prepare a degumming solution, and placing the hemp roving pretreated with a weak acid into the degumming solution for light treatment, and after the light treatment is completed, washing and drying are performed to obtain the degummed hemp roving;

[0011] (5) The degummed flax roving is drawn on a wet spinning frame, twisted into yarn, and then dried and wound onto a bobbin to obtain finished flax roving, i.e., long flax yarn.

[0012] Furthermore, in step (3), the solid-to-liquid ratio of the flax roving to the weak acid reagent is 1:20 to 50.

[0013] Furthermore, the mass concentration of the weak acid reagent in step (3) is 15-30%.

[0014] Furthermore, in step (3), the weak acid reagent is at least one of glycolic acid and lactic acid.

[0015] Furthermore, in step (3), the weak acid pretreatment temperature is 80-100° C., and the pretreatment time is 3-6 hours.

[0016] Furthermore, in step (4), the photocatalyst is a catalyst that can be excited within the visible light wavelength range, and the amount of the photocatalyst used is 2 to 6 g / kg of hemp fiber.

[0017] In the above technical solution, the photocatalyst is a catalyst that can be excited within the visible light wavelength range, and specifically TiO2-CQDs, ZnO-CQDs, ZnIn2S4 or other photocatalysts can be selected. This type of photocatalyst can be excited within the visible light wavelength range, and visible light accounts for 45% of the total energy of sunlight, and its light utilization rate is high, thereby improving the degumming effect.

[0018] Furthermore, the illumination treatment time in step (4) is 20 to 60 hours.

[0019] Furthermore, the light source used in the illumination treatment in step (4) is sunlight or simulated sunlight, and the simulated sunlight is a light emitting diode or a xenon lamp.

[0020] Furthermore, in the step (4), the solid-bath ratio of the flax roving to the degumming solution is 1:10-100.

[0021] Furthermore, the hemp bast is one of ramie, hemp, apocynum, kenaf or jute.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a method for preparing long hemp yarn based on photocatalysis and organic acid treatment combined degumming, which utilizes weak acid pretreatment and photocatalyst to jointly remove pectin, lignin, hemicellulose and other colloid components in hemp. The operation process is simple, the degumming conditions are mild, the degumming effect is good, and the damage to hemp fiber is small. Moreover, the organic acid can be recycled, less waste liquid is generated, and the environmental pollution is small. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Example 1

[0026] This embodiment provides a method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming, comprising the steps of:

[0027] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0028] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0029] (3) placing the hemp roving into a reactor, adding a 20% mass concentration of glycolic acid reagent for pretreatment, the solid-liquid ratio of the hemp roving to the glycolic acid reagent being 1:20, heating the roving at 100° C. for 4 h, and then washing the hemp roving to neutrality after the pretreatment, and drying it in an oven until the fiber weight no longer changes;

[0030] (4) Add 400 ml of 5 g / L TiO 2- The CQDs suspension was added to a 30L glass reactor to prepare a degumming solution, and 1000g of hemp roving pretreated with weak acid was placed in the degumming solution, and water was added to make the solid bath ratio of hemp roving to the degumming solution 1:20, and the mixture was placed under sunlight for illumination treatment for 4 days, specifically, 12 hours of illumination treatment and 12 hours of dark treatment, which was repeated for 4 days. After the illumination treatment, the hemp roving was taken out, washed with water, and dried to obtain degummed hemp roving;

[0031] (5) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0032] Example 2

[0033] This embodiment provides a method for preparing long linen yarn based on photocatalysis and organic acid treatment combined degumming, comprising the steps of:

[0034] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0035] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0036] (3) placing the hemp roving in a reactor, adding a 20% mass concentration of glycolic acid reagent for pretreatment, the solid-liquid ratio of the hemp roving to the glycolic acid reagent being 1:20, heating the hemp roving at 85° C. for 6 h, and then washing the hemp roving to neutrality after the pretreatment, and drying it in an oven until the fiber weight no longer changes;

[0037] (4) Add 500 ml of 10 g / L ZnIn2S4 suspension into a 30 L glass reactor to prepare a degumming solution, and put 1000 g of hemp roving pretreated with weak acid into the degumming solution, add water to make the solid bath ratio of hemp roving to the degumming solution be 1:50, treat with LED light for 20 h, and wash and dry to obtain degummed hemp roving;

[0038] (5) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0039] Comparative Example 1

[0040] This comparative example provides a method for preparing long linen yarn by degumming using a photocatalyst, comprising the steps of:

[0041] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0042] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0043] (3) Add 200 ml of 5 g / L TiO 2- CQDs were added to a 30L glass reactor to prepare a degumming solution, and 1000g of hemp roving pretreated with weak acid was placed in the degumming solution, water was added to make the solid bath ratio of hemp roving to the degumming solution 1:20, and the treatment was carried out in the dark for 4 days. After the treatment was completed, the hemp roving was taken out, washed with water, and dried to obtain degummed hemp roving;

[0044] (4) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0045] Comparative Example 2

[0046] This comparative example provides a method for preparing long linen yarn by degumming using a photocatalyst, comprising the steps of:

[0047] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0048] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0049] (3) Add 400 ml of 5 g / L TiO 2- The CQDs suspension was added to a 30L glass reactor to prepare a degumming solution, and 1000g of hemp roving pretreated with weak acid was placed in the degumming solution, and water was added to make the solid bath ratio of hemp roving to the degumming solution 1:20, and the mixture was placed under sunlight for illumination treatment for 4 days, specifically, 12 hours of illumination treatment and 12 hours of dark treatment, which was repeated for 4 days. After the illumination treatment, the hemp roving was taken out, washed with water, and dried to obtain degummed hemp roving;

[0050] (4) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0051] Comparative Example 3

[0052] This comparative example provides a method for preparing long linen yarn by acid treatment degumming, comprising the steps of:

[0053] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0054] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0055] (3) placing the hemp roving into a reactor, adding a 20% mass concentration of glycolic acid reagent for pretreatment, the solid-liquid ratio of the hemp roving to the glycolic acid reagent being 1:20, heating the roving at 100° C. for 4 h, and then washing the hemp roving to neutrality after the pretreatment, and drying it in an oven until the fiber weight no longer changes;

[0056] (4) putting 1000 g of the flax roving pretreated with weak acid into a 30 L glass container, adding water, the solid bath ratio of the flax roving to the solution being 1:20, treating in the dark for 4 days, taking out the flax roving after the treatment, washing it with water, and drying it to obtain degummed flax roving;

[0057] (5) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0058] Comparative Example 4

[0059] This comparative example provides a method for preparing long linen yarn by acid treatment degumming, comprising the steps of:

[0060] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0061] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0062] (3) placing the hemp roving into a reactor, adding a 20% mass concentration of glycolic acid reagent for pretreatment, the solid-liquid ratio of the hemp roving to the glycolic acid reagent being 1:20, heating the roving at 100° C. for 4 h, and then washing the hemp roving to neutrality after the pretreatment, and drying it in an oven until the fiber weight no longer changes;

[0063] (4) placing 1000 g of the flax roving pretreated with weak acid into a 30 L glass container, adding water, the solid bath ratio of the flax roving to the solution being 1:20, and placing it under sunlight for illumination treatment for 4 days, specifically, 12 hours of illumination treatment followed by 12 hours of dark treatment, and repeating this for 4 days. After the treatment is completed, taking out the flax roving, washing it with water, and drying it to obtain degummed flax roving;

[0064] (5) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0065] Comparative Example 5

[0066] This comparative example provides a method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment, comprising the steps of:

[0067] (1) beating the hemp bast into hemp, and after the preparatory processes such as humidification, curing, bundle division, and initial combing, combing is performed on a combing machine to obtain parallel and straight long hemp bundles with a certain length, linear density and weight;

[0068] (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by four drawing machines to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain roving;

[0069] (3) placing the hemp roving into a reactor, adding a 20% mass concentration of glycolic acid reagent for pretreatment, the solid-liquid ratio of the hemp roving to the glycolic acid reagent being 1:20, heating the roving at 100° C. for 4 h, and then washing the hemp roving to neutrality after the pretreatment, and drying it in an oven until the fiber weight no longer changes;

[0070] (4) Add 400 ml of 5 g / L TiO 2-CQDs were added to a 30L glass reactor to prepare a degumming solution, and 1000g of hemp roving pretreated with weak acid was placed in the degumming solution, water was added to make the solid bath ratio of hemp roving to the degumming solution 1:20, and the treatment was carried out in the dark for 4 days. After the treatment was completed, the hemp roving was taken out, washed with water, and dried to obtain degummed hemp roving;

[0071] (5) The degummed flax roving is passed through a water tank (with water, penetrant, softener, etc.) on a wet spinning frame and then stretched to split and thin the process fibers into finer fiber bundles. The yarn is then twisted into yarn, dried, and wound onto a bobbin to obtain the finished flax roving, i.e., long flax yarn.

[0072] In addition, the chemical composition of the long linen yarn and hemp bast prepared in the above-mentioned Example 1 and Comparative Examples 1-5 was tested, and the test results are shown in Table 1. The physical properties of the original hemp and the long linen yarn prepared in Example 1 were tested, and the test results are shown in Table 2.

[0073] The above chemical composition test and physical property test methods are as follows:

[0074] Testing method for chemical composition: Refer to GB 5889-1986 "Quantitative analysis method for chemical composition of ramie" to test the residual gum rate of degummed hemp fiber.

[0075] Test method for fineness: Refer to GB / T 6100-2007 "Test method for linear density of cotton fibers - mid-section weighing method" to test the fineness of degummed hemp fibers.

[0076] Test method for bundle fiber strength: refer to GB / T 5882-1986 "Test method for breaking strength of ramie bundle fibers" to test the strength of degummed hemp fibers.

[0077] Table 1

[0078]

[0079] Table 2

[0080]

[0081] It can be seen from Table 1 above that Example 1 uses weak acid and TiO2-CQDs to treat under light conditions, and the prepared hemp fiber has the highest removal rate of wax, pectin, lignin, hemicellulose and other colloids; compared with Example 1, Comparative Example 5 is treated under dark conditions, and its wax, pectin, lignin, hemicellulose and other contents are higher than those of Example 1; Comparative Example 1 uses TiO2-CQDs to treat under dark conditions, and the content of each colloid is still very high; Comparative Example 2 only uses TiO2-CQDs to treat under light conditions, and the content of each colloid is still very high, and pectin, lignin and hemicellulose are only slightly reduced; Comparative Examples 3 and Comparative Examples 4 use weak acid for dark treatment or light treatment, and part of the pectin, wax, lignin, hemicellulose, etc. is removed, but the content of pectin, lignin, hemicellulose, etc. is still relatively high.

[0082] It can be seen from Table 2 above that Example 1 adopts a weak acid and TiO2-CQDs photocatalyst combined degumming process. After degumming, the fiber fineness is 53Nm, the breaking strength is 43cN / dtex, the yarn is uniform, the degumming effect is good, the colloid bonding between single fibers is reduced, the hemp fiber fineness is finer, the fiber has better dispersibility, and the reaction conditions of this Example 1 are mild, which causes less damage to the hemp fiber, so that the long hemp yarn has better breaking strength and the breaking strength remains basically unchanged.

[0083] It should be noted that some parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0084] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment, characterized in that: Includes steps: (1) beating hemp bast into hemp, and after the pre-combing preparation process, combing on a combing machine to obtain parallel and straight long hemp bundles; (2) The long flax bundles are processed into continuous flax strips on a slitting machine, and then drawn and combined by 3 to 5 drawing frames to produce long flax strips with uniform structure and parallel straightness, which are then drawn, twisted and wound by a roving machine to obtain flax roving; (3) placing the hemp roving into a reactor, adding a weak acid reagent for pretreatment, washing the hemp roving to neutrality after the pretreatment, and drying it; (4) adding a photocatalyst into a glass reactor to prepare a degumming solution, and placing the hemp roving pretreated with a weak acid into the degumming solution for light treatment, and after the light treatment is completed, washing and drying are performed to obtain the degummed hemp roving; (5) The degummed flax roving is drawn on a wet spinning frame, twisted into yarn, and then dried and wound onto a bobbin to obtain finished flax roving, i.e., long flax yarn.

2. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: In the step (3), the solid-to-liquid ratio of the flax roving to the weak acid reagent is 1:20-50.

3. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: The mass concentration of the weak acid reagent in step (3) is 15-30%.

4. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: In the step (3), the weak acid reagent is at least one of glycolic acid and lactic acid.

5. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: In the step (3), the weak acid pretreatment temperature is 80-100° C., and the pretreatment time is 3-6 hours.

6. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: The photocatalyst in step (4) is a catalyst that can be excited within the visible light wavelength range, and the amount of the photocatalyst used is 2-6 g / kg of hemp fiber.

7. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: The illumination treatment time in step (4) is 20 to 60 hours.

8. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: The light source used in the illumination treatment in step (4) is sunlight or simulated sunlight, and the simulated sunlight is a light emitting diode or a xenon lamp.

9. The method for preparing long linen yarn by combined degumming based on photocatalysis and organic acid treatment according to claim 1, characterized in that: In the step (4), the solid-bath ratio of the flax roving to the degumming solution is 1:10-100.

10. A method for preparing flax yarn based on photocatalysis and organic acid treatment combined degumming according to any one of claims 1 to 9, characterized in that: The hemp bast is one of ramie, hemp, apocynum, kenaf or jute.

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