A method for preparing refined industrial hemp fiber

Abstract

The invention discloses a method for preparing refined industrial hemp fiber, comprising: 1) placing industrial hemp in a mixture of polyethylene glycol and water for degumming; wherein, in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is (0.10-0.50):1; 2) using a composite enzyme for degumming and washing; 3) sodium percarbonate bleaching, washing, and drying. Compared with the traditional degumming process, the method of the invention has less damage to the industrial hemp fiber and improves the quality of the refined industrial hemp fiber. The invention treats the industrial hemp with a mixture of polyethylene glycol and water, and uses sodium percarbonate for bleaching. Compared with the traditional process, the polyethylene glycol is non-toxic and non-irritating; sodium percarbonate bleaching eliminates the risk of hydrogen peroxide being flammable and explosive during transportation and storage, and does not need to add sodium carbonate; the method is eco-friendly, simple to prepare, and reduces the amount of chemical reagents used.

Description

Technical Field

[0001] The invention belongs to the technical field of textile processing, and in particular relates to a highly efficient and environmentally friendly preparation method of refined industrial hemp fiber. Background Art

[0002] The raw hemp fiber of industrial hemp feels hard and has a complex chemical composition. It is composed of cellulose and non-cellulose components such as pectin, hemicellulose and lignin. These non-cellulose components are collectively called colloids. The content of pectin, wax and other substances is not high. Lignin and hemicellulose are the focus of degumming treatment. The content of colloids has a great impact on the subsequent textile processing of industrial hemp. Therefore, in order to smoothly proceed with the subsequent textile process, it is a crucial step to remove these non-cellulose colloid components to obtain purer cellulose fibers. At present, the count of pure hemp spinning products is relatively low. In order to obtain high-count yarn and blended yarn, hemp needs to be further refined.

[0003] The fine processing of hemp is mainly to degumming hemp. There are many methods of degumming. The physical degumming methods mainly include mechanical degumming, steam explosion-flash explosion degumming, ultrasonic degumming, etc., which are mainly auxiliary degumming. Chemical degumming is widely used, but it pollutes the environment. Compared with chemical degumming, the conditions of biological enzyme degumming are milder, the fiber damage is small, the hemp yield is high, the energy consumption is small, and the pollution is small, but there are disadvantages of incomplete degumming and large quality differences. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the embodiment of the present invention provides an efficient and environmentally friendly preparation method for refined industrial hemp fiber. The method of the present invention is simple, low-cost, short processing time, and small amount of chemical reagents. The refined industrial hemp fiber obtained is of high quality.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The embodiment of the present invention provides a method for preparing refined industrial hemp fiber, comprising the following steps:

[0007] 1) placing industrial hemp in a mixture of polyethylene glycol and water for degumming and washing; wherein the mass ratio of polyethylene glycol to water in the mixture of polyethylene glycol and water is (0.10-0.50):1;

[0008] 2) Degumming with compound enzyme and washing with water;

[0009] 3) Bleaching with sodium percarbonate, washing and drying.

[0010] In some embodiments of the present invention, in step 1), the cannabis is placed in a mixture of polyethylene glycol and water at a bath ratio of 1:50-150, the temperature is 20-30° C., the treatment time is 1-2 h, and the cannabis is washed with water until the pH value is neutral.

[0011] In the embodiment of the present invention, the mass ratio of polyethylene glycol to water is (0.10-0.50):1; the inventors found that when the mass ratio of polyethylene glycol to water in the mixed solution is less than 0.1:1, the amount of polyethylene glycol is too small, so the degumming effect on the hemp fiber is very small. When the mass ratio of polyethylene glycol to water is greater than 0.5:1, the concentration of polyethylene glycol is too high, and it is easy to cause damage to the fiber after treatment. In this application, the mass ratio of polyethylene glycol to water is controlled to be between (0.10-0.50):1, which has a better degradation effect on hemicellulose, lignin, pectin and water-soluble substances, especially the removal rate of lignin is higher, and the damage to the fiber is less.

[0012] Preferably, in step 1), in the mixed solution of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is (0.10-0.30):1, the cannabis is placed in the mixed solution of polyethylene glycol and water at a bath ratio of 1:50-100, the temperature is 20-30°C, the treatment time is 1-2h, and the cannabis is washed with water until the pH value is neutral.

[0013] In some embodiments of the present invention, in step 2), the bath ratio is 1:20, the pH value is 3.0-6.0 (preferably 3.5-5), the temperature is 35-50°C, the time is 30-90 min, the amount of complex enzyme added is 20 g / L, and the water is washed until the pH value is neutral.

[0014] In some embodiments of the present invention, the composite enzyme is pectinase and hemicellulase, and the mass ratio is: (1-2): (1-2).

[0015] In some embodiments of the present invention, in step 3), the bath ratio is 1:10-30, the sodium hydroxide is 2-5 g / L, the sodium percarbonate is 10-30 g / L, the treatment time is 30-50 min, the temperature is 60-90° C., washing with water until the pH value is neutral; and drying to a fiber dry state.

[0016] The inventors found that in step 3), when other conditions remain unchanged, the amount of sodium percarbonate increases, the whiteness of the fiber increases, the residual glue rate decreases, but the breaking strength also decreases; when the sodium percarbonate is 20-25g / L, the whiteness is higher, the residual glue rate is lower, and the breaking strength is higher. Taking all factors into consideration, the sodium percarbonate concentration is preferably 20-25g / L.

[0017] The process flow of the present invention is as follows: preparing a mixture of polyethylene glycol and water - degumming hemp fibers in the mixture - degumming treatment with a composite enzyme - sodium percarbonate bleaching - washing - drying. The present invention first uses a mixture of polyethylene glycol and water to treat hemp in view of the properties of the object to be degummed. Polyethylene glycol is a high molecular polymer with a chemical structural formula: HO(CH2CH2O)nH (such as PEG200, etc.). It is non-irritating, slightly bitter, has good water solubility, and is an environmentally friendly chemical reagent. The mixture of polyethylene glycol and water can dissolve a portion of the colloid in the hemp at room temperature (20-30°C) and causes little damage to the fibers. General organic solvents (such as ethylene glycol, 1,2-propylene glycol, glycerol / 1,4-butanediol, etc.) need to be at high temperature (such as 180°C), while the mixture of polyethylene glycol and water only needs to be carried out at room temperature, which consumes little energy. Then, the biological degumming method of the composite enzyme is used to degumming the hemp fibers in which a portion of the colloid has been dissolved, which is environmentally friendly. Finally, bleaching. The bleaching method in the related art is to use chlorine-containing reagents such as sodium hypochlorite to bleach textile fibers. The effect is fast and the quality is high, but the released Cl2 is very harmful to the human body; oxygen bleaching uses hydrogen peroxide, which is activated under alkaline conditions and has strong oxidizing properties. The presence of heavy metal ions causes the hydrogen peroxide to catalyze and decompose prematurely, which not only causes the bleaching solution to fail, but also causes fiber damage. Therefore, it is necessary to add a stabilizer (such as sodium carbonate) to slow down the decomposition rate of hydrogen peroxide. At the same time, the high pH value of the degumming liquid will cause pollution to the environment after discharge; therefore, the present invention explores and studies a new bleaching method, using sodium percarbonate bleaching to bleach industrial hemp. Sodium percarbonate is an environmentally friendly solid oxidant. After decomposition, it can produce hydrogen peroxide and sodium carbonate. When sodium percarbonate is used instead of hydrogen peroxide for degumming, sodium carbonate can no longer be added, but the sodium carbonate obtained by decomposing sodium percarbonate can be directly used.

[0018] The present invention has the following beneficial effects:

[0019] (1) Compared with the traditional degumming process, the method of the present invention causes less damage to industrial hemp fibers and improves the quality of refined industrial hemp fibers.

[0020] (2) The present invention uses a mixture of polyethylene glycol and water to treat industrial hemp, and uses sodium percarbonate for bleaching. Compared with the traditional process, polyethylene glycol is non-toxic and non-irritating; sodium percarbonate bleaching eliminates the risk of flammability and explosion of hydrogen peroxide during transportation and storage, and there is no need to add additional sodium carbonate.

[0021] (3) The method of the present invention is eco-friendly, simple to prepare, reduces the amount of chemical reagents used, and has a safe process, which is more conducive to environmental protection and sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM image of cannabis before treatment in Example 1 of the present invention;

[0023] Figure 2 This is a SEM image of hemp fiber treated by the method of Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0025] Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0026] Where values ​​are described herein as a range, it should be understood that such disclosure includes disclosure of all possible sub-ranges within that range, as well as specific values ​​falling within that range, regardless of whether a specific value or a specific sub-range is explicitly stated.

[0027] It should be noted that the following comparative examples are not prior art and are provided only for comparison with the embodiments and are not intended to limit the present invention.

[0028] Source of reagents in the present invention:

[0029] Polyethylene glycol (PEG200): purchased from Wuxi Yatai United Chemical Co., Ltd.

[0030] Pectinase: purchased from Suzhou Fulide Biotechnology Co., Ltd.

[0031] Hemicellulase: purchased from Ningxia Xiasheng Industrial Group Co., Ltd.

[0032] Sodium hydroxide: purchased from Tianjin Kaitong Chemical Reagent Co., Ltd.

[0033] Sodium percarbonate: purchased from Sinopharm Chemical Reagent Co., Ltd.

[0034] Example 1

[0035] A highly efficient and environmentally friendly method for preparing refined industrial hemp fiber comprises the following steps:

[0036] 1) Degumming of the mixture of polyethylene glycol and water

[0037] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.15:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50, the temperature is 25°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0038] 2) Further degumming by complex enzyme

[0039] The conditions are as follows: the composite enzyme uses pectinase and hemicellulase in a mass ratio of 1:1, the concentration of the composite enzyme is 20 g / L, the enzyme reaction temperature is 40°C, the pH is 5 (adjusted with citric acid and sodium bicarbonate), the enzyme reaction time is 1 h, the bath ratio is 1:20, and the solution is washed with water until the pH is neutral.

[0040] 3) Bleaching with sodium percarbonate

[0041] The conditions are: bath ratio of 1:10, sodium hydroxide of 2 g / L, sodium percarbonate concentration of 10 g / L, treatment time of 50 min, temperature of 70°C, washing to neutral pH, and drying to a fiber dry state.

[0042] Figure 1 This is a SEM image of cannabis before treatment in Example 1 of the present invention. Figure 2 This is a SEM image of hemp fiber after being treated by the method of Example 1 of the present invention. Figure 1 and Figure 2 By comparison, it can be seen that the hemp fiber obtained by the method of the embodiment of the present invention has a small diameter, a low residual rubber rate, little damage to the hemp fiber, and a high quality of the hemp fiber.

[0043] Example 2

[0044] A highly efficient and environmentally friendly method for preparing refined industrial hemp fiber comprises the following steps:

[0045] 1) Degumming of the mixture of polyethylene glycol and water

[0046] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.2:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50, the temperature is 30°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0047] 2) Further degumming by complex enzyme

[0048] The conditions are as follows: the composite enzyme uses pectinase and hemicellulase in a mass ratio of 2:1, the concentration of the composite enzyme is 20 g / L, the enzyme reaction temperature is 35°C, the pH is 4.5 (adjusted with citric acid and sodium bicarbonate), the enzyme reaction time is 1 h, the bath ratio is 1:20, and the solution is washed with water until the pH is neutral.

[0049] 3) Bleaching with sodium percarbonate

[0050] The conditions are: bath ratio of 1:20, sodium hydroxide of 5 g / L, sodium percarbonate concentration of 15 g / L, treatment time of 45 min, temperature of 60°C, washing with water until the pH value is neutral, and drying to a fiber dry state.

[0051] Example 3

[0052] A highly efficient and environmentally friendly method for preparing refined industrial hemp fiber comprises the following steps:

[0053] 1) Degumming of the mixture of polyethylene glycol and water

[0054] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.2:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50, the temperature is 30°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0055] 2) Further degumming by complex enzyme

[0056] The conditions are as follows: the composite enzyme uses pectinase and hemicellulase in a mass ratio of 1:2, the concentration of the composite enzyme is 20 g / L, the enzyme reaction temperature is 40°C, the pH is 4 (adjusted with citric acid and sodium bicarbonate), the enzyme reaction time is 1.5 h, the bath ratio is 1:20, and the solution is washed with water until the pH is neutral.

[0057] 3) Bleaching with sodium percarbonate

[0058] The conditions are: bath ratio of 1:30, sodium hydroxide of 3 g / L, sodium percarbonate concentration of 20 g / L, treatment time of 50 min, temperature of 70°C, washing to neutral pH, and drying to a fiber dry state.

[0059] Example 4

[0060] A highly efficient and environmentally friendly method for preparing refined industrial hemp fiber comprises the following steps:

[0061] 1) Degumming of the mixture of polyethylene glycol and water

[0062] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.25:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:60, the temperature is 30°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0063] 2) Further degumming by complex enzyme

[0064] The conditions are as follows: the composite enzyme uses pectinase and hemicellulase in a mass ratio of 1:1, the concentration of the composite enzyme is 20 g / L, the enzyme reaction temperature is 30°C, the pH is 5 (adjusted with citric acid and sodium bicarbonate), the enzyme reaction time is 1.5 h, the bath ratio is 1:20, and the solution is washed with water until the pH is neutral.

[0065] 3) Bleaching with sodium percarbonate

[0066] The conditions are: bath ratio of 1:20, sodium hydroxide of 4 g / L, sodium percarbonate concentration of 30 g / L, treatment time of 35 min, temperature of 60°C, washing with water until the pH value is neutral, and drying to a fiber dry state.

[0067] Example 5

[0068] A highly efficient and environmentally friendly method for preparing refined industrial hemp fiber comprises the following steps:

[0069] 1) Degumming of the mixture of polyethylene glycol and water

[0070] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.25:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50, the temperature is 30°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0071] 2) Further degumming by complex enzyme

[0072] The conditions are as follows: the composite enzyme uses pectinase and hemicellulase in a mass ratio of 2:1, the concentration of the composite enzyme is 20 g / L, the enzyme reaction temperature is 40°C, the pH is 4 (adjusted with citric acid and sodium bicarbonate), the enzyme reaction time is 1 h, the bath ratio is 1:20, and the solution is washed with water until the pH is neutral.

[0073] 3) Bleaching with sodium percarbonate

[0074] The conditions are: bath ratio of 1:20, sodium hydroxide of 4 g / L, sodium percarbonate concentration of 10 g / L, treatment time of 35 min, temperature of 80°C, washing with water until the pH value is neutral, and drying to a fiber dry state.

[0075] Comparative Example 1

[0076] The difference from Example 1 is that: Step 1) Soaking the cannabis in clean water: Soak the cannabis in clean water for 1 hour. The other steps are the same as Example 1.

[0077] Comparative Example 2

[0078] The difference from Example 1 is: Step 1) Soaking the cannabis in warm water: Soak the cannabis in 30° C. warm water for 1 hour, and the other steps are the same as Example 1.

[0079] Comparative Example 3

[0080] A refined industrial hemp fiber degumming method comprises the following steps:

[0081] The conditions are: in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is 0.15:1, the cannabis is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50, the temperature is 25°C, the treatment time is 1 hour, and it is washed with water until the pH value is neutral.

[0082] Comparative Example 4

[0083] The difference from Example 1 is that in step 2), the composite enzyme uses xylanase and hemicellulase in a mass ratio of 1:1, and the other steps are the same as in Example 1.

[0084] Comparative Example 5

[0085] The difference from Example 1 is that in step 1), the mass ratio of polyethylene glycol to water in the mixed solution of polyethylene glycol and water is 0.6:1, the cannabis is placed in the mixed solution of polyethylene glycol and water at a bath ratio of 1:40, the temperature is 35° C., the treatment time is 3 hours, and the cannabis is washed with water until the pH value is neutral. The other steps are the same as Example 1.

[0086] Comparative Example 6

[0087] The difference from Example 1 is that in step 3), the bath ratio is 1:40, the sodium hydroxide is 6 g / L, the sodium percarbonate is 40 g / L, the treatment time is 60 min, the temperature is 100° C., the fiber is washed with water until the pH value is neutral, and dried until the fiber is dry. The other steps are the same as in Example 1.

[0088] Comparative Example 7

[0089] Step 3) bleaching the cannabis with hydrogen peroxide, washing with water, and drying. The other steps are the same as those in Example 1.

[0090] The physical properties of the refined industrial hemp fibers prepared by the methods of the embodiments of the present invention and the comparative examples were tested, and the following test data were obtained:

[0091] The breaking strength is tested by LLY-06E electronic single fiber strength tester, the stretching distance is 20mm / min, the stretching times are 20 times, and the average value is taken;

[0092] The reference standard for the detection of residual glue rate is GB / T18147.2-2008;

[0093] The reference standard for whiteness testing is GB / T17644-2008;

[0094] The diameter of refined industrial hemp fiber was tested by YGB-002 fiber fineness meter, and different parts were tested 20 times to take the average value.

[0095] Table 1 Detection data of refined industrial hemp fiber

[0096]

[0097] The processing object of the present invention is industrial hemp. The industrial hemp fiber obtained by degumming by the method of the present invention has a diameter of 17-28 μm, a residual glue rate of 4.2-6.0%, a breaking strength of 35-44 cN, and a whiteness of 24-27%. It can be seen that the refined industrial hemp fiber obtained by the method of the present invention has a small diameter, a low residual glue rate, low environmental pollution, little damage to the hemp fiber, and high quality.

[0098] By comparing the data of Example 1 and Comparative Example 1, it can be seen that the diameter of the refined industrial hemp fiber is relatively coarse in Comparative Example 1 (Example 1 is 20.543 μm, Comparative Example 1 is 37.935 μm), the residual glue rate is high in Comparative Example 1 (Example 1 is 5.01%, Comparative Example 1 is 10.92%), the breaking strength is high in Comparative Example 1 (Example 1 is 36.95 cN, Comparative Example 1 is 48.87 cN), and the whiteness is poor in Comparative Example 1 (Example 1 is 26.91%, Comparative Example 1 is 24.89%). This also proves that in the pretreatment stage, the degumming effect of using a mixed solution of polyethylene glycol and water is better than that of using only water immersion, and it also proves that the mixed solution of polyethylene glycol and water has a degumming effect.

[0099] By comparing the data of Example 1 and Comparative Example 2, it can be seen that the diameter of the refined industrial hemp fiber is relatively coarse in Comparative Example 1 (Example 1 is 20.543 μm, and Comparative Example 2 is 34.587 μm), the residual glue rate is high in Comparative Example 2 (Example 5.01%, Comparative Example 2 is 8.07%), the breaking strength is high in Comparative Example 2 (Example 1 is 36.95 cN, Comparative Example 2 is 44.98 cN), and the whiteness is relatively poor in Comparative Example 2 (Example 1 is 26.91%, Comparative Example 2 is 25.91%), but similar. This also proves that in the pretreatment stage, the degumming effect of using a mixture of polyethylene glycol and water is better than that of soaking in warm water, and it also proves that the mixture of polyethylene glycol and water has a degumming effect.

[0100] By comparing the data of Example 1 and Comparative Example 3, it can be seen that the diameter of the refined industrial hemp fiber (Comparative Example 3) is relatively coarse (20.543 μm for Example 1 and 27.896 μm for Comparative Example 3) compared with Example 1, but the difference is not big, indicating that the degumming effect of the mixed solution of polyethylene glycol and water is better; the residual glue rate is slightly higher than that of Comparative Example 3 (5.01% for Example 1 and 7.89% for Comparative Example 3), the breaking strength is slightly higher than that of Comparative Example 3 (36.95 cN for Example 1 and 40.15 cN for Comparative Example 3); the whiteness is greatly different (26.91% for Example 1 and 18.98% for Comparative Example 3). It shows that the mixed solution of polyethylene glycol and water has little effect on bleaching.

[0101] By comparing the data of Example 1 and Comparative Example 4, it can be seen that when the types of composite enzymes are changed to xylanase and hemicellulase, under the condition that other conditions remain unchanged, the diameter of the refined industrial hemp fiber in Comparative Example 4 is slightly coarser (Example 1 is 20.543μm, Comparative Example 4 is 23.142μm), the residual glue rate in Comparative Example 4 is slightly higher (Example 5.01%, Comparative Example 4 is 6.12%), the breaking strength in Comparative Example 4 is slightly higher (Example 1 is 36.95cN, Comparative Example 4 is 36.98cN), and the whiteness is similar (Example 1 is 26.91%, Comparative Example 4 is 26.12%). This is because the mixed liquid of polyethylene glycol and water has a better decomposition effect on lignin. In Example 1, the composite enzyme using pectinase and hemicellulase is conducive to removing pectin and hemicellulose in hemp; in the comparative example, the composite enzyme using xylanase and hemicellulase, both enzymes have an effect on the removal of hemicellulose, but have no effect on the removal of pectin, so the overall colloid removal is not as good as in Example 1. But the pectin content in hemp is not as high as the hemicellulose content, so the difference is not much.

[0102] By comparing the data of Example 1 and Comparative Example 5, it can be seen that the diameter of the refined industrial hemp fiber in Comparative Example 5 is slightly finer (Example 1 is 20.543μm, and Comparative Example 5 is 19.218μm), the residual glue rate in Comparative Example 5 is lower (Example 5 is 5.01%, and Comparative Example 5 is 4.91%), the breaking strength in Comparative Example 5 is lower (Example 1 is 36.95cN, and Comparative Example 5 is 33.25cN), and the whiteness is similar (Example 1 is 26.91%, and Comparative Example 5 is 26.41%). In Comparative Example 5, the mass ratio of polyethylene glycol to water in step 1) is increased compared with Example 1, the bath ratio of hemp is reduced to 1:40, the temperature is high, the processing time is long, and the other steps are the same as Example 1. These reaction conditions enhance the effect on the fiber, but the damage to the fiber is greater, so the diameter is not much different, but the difference in breaking strength is relatively large.

[0103] By comparing the data of Example 1 and Comparative Example 6, it can be seen that the diameter of the refined industrial hemp fiber in Comparative Example 6 is thinner (Example 1 is 20.543μm, and Comparative Example 6 is 18.845μm), the residual glue rate in Comparative Example 6 is lower (Example 5.01%, Comparative Example 6 is 4.35%), the breaking strength in Comparative Example 6 is lower (Example 1 is 36.95cN, Comparative Example 6 is 31.41cN), and the whiteness in Comparative Example 6 is better (Example 1 is 26.91%, Comparative Example 6 is 27.12%). In Comparative Example 6, compared with Example 1, the amount of sodium hydroxide and sodium percarbonate in step 3) is increased, the processing time is prolonged, and the temperature is increased. The other steps are the same as Example 1. These reaction conditions enhance the effect on the fiber, especially the increase in the amount of sodium hydroxide and sodium percarbonate, the damage to the fiber is obvious, the breaking strength is low, but the whiteness is better.

[0104] By comparing the data of Example 1 and Comparative Example 7, it can be seen that in step 3), sodium percarbonate is replaced with hydrogen peroxide compared with Example 1, and the other steps are the same as Example 1. The various indicators are not much different, but the loss of breaking strength is large. In addition, the sodium percarbonate bleaching of the present invention eliminates the risk of hydrogen peroxide being flammable and explosive during transportation and storage.

[0105] The above is only a preferred embodiment of the present invention, and does not limit the technical solution of the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing refined industrial hemp fiber, characterized in that: The steps include: 1) Place industrial hemp in a mixture of polyethylene glycol and water for degumming and water washing; wherein, in the mixture of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is (0.10-0.50):1, and the hemp is placed in the mixture of polyethylene glycol and water at a bath ratio of 1:50-150, the temperature is 20-30°C, the treatment time is 1-2h, and the hemp is washed with water until the pH value is neutral; 2) Degumming with a composite enzyme and washing with water; the bath ratio is 1:20, the pH value is 3.0-6.0, the temperature is 35-40°C, the time is 30-90 min, the amount of composite enzyme added is 20 g / L, and washing with water until the pH value is neutral; the composite enzyme is pectinase and hemicellulase, and the mass ratio is (1-2): (1-2); 3) Sodium percarbonate bleaching, water washing, drying, bath ratio of 1:10~30, sodium hydroxide 2~5g / L, sodium percarbonate 10~30g / L, treatment time 30~50min, temperature 60~90℃, water washing until pH value is neutral, and then drying to fiber dry state.

2. The method for preparing refined industrial hemp fiber according to claim 1, characterized in that: In step 1), in the mixed solution of polyethylene glycol and water, the mass ratio of polyethylene glycol to water is (0.10-0.30):1, and cannabis is placed in the mixed solution of polyethylene glycol and water at a bath ratio of 1:50-100.

3. The method for preparing refined industrial hemp fiber according to claim 1, characterized in that: The sodium percarbonate concentration is 20-25 g / L.

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