Graft-modified vinasse textile size and preparation method thereof

Abstract

The invention belongs to the technical field of biomass size used for textile warp sizing, and discloses a preparation method of graft modified vinasse textile size, which comprises the following steps: treating vinasse raw materials with a sodium hydroxide solution to remove impurities (such as holocellulose, lignin and ash); effective components (such as starch and protein) which can be used for the textile size are integrally extracted; then, under the initiation action of a proper redox system, a certain amount of hydrophilic vinyl monomer is grafted to a molecular chain of the vinasse extract, and graft modified vinasse slurry which can be dissolved in water under the neutral condition is prepared. The graft-modified vinasse slurry prepared by the method has good water solubility under a neutral condition (pH 6.5-7.5), the use performance of the slurry can be obviously improved, main sizing objects such as wool, silk and other natural fiber yarns are protected from being damaged by alkaline agents, and resource utilization and high-value utilization of a byproduct vinasse in the brewing industry are effectively achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass sizing agents used in textile warp sizing, and particularly relates to a graft-modified distiller's grains textile sizing agent and a preparation method thereof. Background Art

[0002] China's brewing industry is large in scale. Taking "national liquor" yellow rice wine as an example, according to the data released by the China National Liquor Industry Association, in 2023, there were more than 700 yellow rice wine production enterprises nationwide, and the total brewing output reached 1.9 million kiloliters. Calculated according to the approximate ratio of producing 6 kilograms of distiller's grains for every 1 kilogram of yellow rice wine brewed, only yellow rice wine enterprises in China produce tens of millions of tons of distiller's grains every year. Due to the huge output of distiller's grains, some researchers have used distiller's grains for animal feed, anaerobic digestion, fermentation to produce ethanol fuel, etc. However, the distiller's grains consumed by these applications only account for a very small part of the total annual output of distiller's grains, and there is still a large amount of distiller's grains that need to be treated by traditional methods that harm the environment, such as landfilling and incineration. The reduction, harmless treatment, and high-value utilization of distiller's grains waste have become an important topic related to the sustainable development of the brewing industry, ecological environment protection, and new material development. The composition of distiller's grains is complex. Besides moisture, it mainly contains starch, protein, holocellulose, lignin, and ash, etc. The proportion of each component varies slightly due to the variety of wine and the brewing method. However, the starch and protein components that can be used for textile sizing agents are basically maintained at relatively high mass ratios of 15% - 35% and 12% - 40% in dry distiller's grains.

[0003] In recent years, there have been some publicly available literatures on the resource utilization and high-value utilization of distiller's grains; for example, the invention patent application with the publication number CN115368474A discloses a preparation method of distiller's grains-based lyocell fiber pulp. This method sequentially treats the distiller's grains raw material with dilute sulfuric acid, sodium hydroxide / sodium sulfite, and p-toluenesulfonic acid aqueous solution to obtain distiller's grains-based lyocell fiber pulp, and the cellulose purity of this pulp is as high as over 90%, which can be used to prepare lyocell fibers. Another example is the invention patent application with the publication number CN116837654A, which discloses an environment-friendly preparation method of distiller's grains-based lyocell fiber pulp. This method sequentially treats the distiller's grains raw material with high-temperature and high-pressure cooking, sodium hydroxide / sodium sulfite, amylase, and protease treatments, and also obtains distiller's grains-based lyocell fiber pulp with relatively high cellulose purity. The above publicly available literatures have played a positive role in promoting the high-value utilization of distiller's grains and effectively extracting and utilizing the cellulose components in distiller's grains. However, for the starch, protein, and other components in distiller's grains, the above literatures degrade them through methods such as amylase / strong acid, protease / strong base, etc., and these components basically lose their utilization value after degradation, inevitably causing waste of resources.

[0004] The invention patent application with the publication number of CN112062915 A discloses a preparation method of a distillers' grains - enhanced polycarboxylate water - reducing agent. This method uses ammonium persulfate or potassium persulfate as an initiator, and grafts and polymerizes the double - bond - containing distillers' grains with a modified acrylate, magnesium acrylate, and acrylic acid mixture at 65 - 75 °C to prepare a distillers' grains - enhanced polycarboxylate water - reducing agent. This method has high requirements for the distillers' grains raw material. Only double - bond - containing distillers' grains can be used for graft polymerization reaction. In addition, since this method uses a single persulfate, the required reaction temperature is relatively high (65 - 75 °C), which will cause most of the starch components in the distillers' grains to dissolve in water during the reaction, and it is impossible to achieve solid - liquid separation by filtration, resulting in difficulty in separating and collecting the starch components from the aqueous phase.

[0005] In the textile industry, sizing agents are the second - largest consumption production raw materials. Only in China, the annual consumption of sizing agents in the textile industry has reached about 1 million tons. The warp yarn needs to be desized after sizing, which puts forward relatively high requirements for the biodegradability of the sizing agent. If a widely - sourced and low - cost polymer material can be extracted from renewable agricultural and sideline products and used as a textile sizing agent, it can obviously conform to the environmental protection trend and promote the sustainable development of the textile sizing industry. The warp - sizing process needs to be completed in an aqueous system, which makes it a prerequisite for a polymer material to be used as a textile sizing agent to have water - solubility or at least good water - dispersibility. Starch is the sizing agent with the largest usage. It has good sizing performance for natural fiber yarns and is environmentally friendly. However, due to its high crystallinity and strong hydrogen - bond association, it can only be dissolved after gelatinization in hot water above 60 °C, which will cause performance damage to heat - sensitive fibers (such as wool and silk) yarns. There are very few varieties of plant proteins that can be used as textile sizing agents. The main reason is that most plant proteins have very poor water - solubility and are difficult to prepare into sizing solutions. Taking the protein in distillers' grains as an example, its main component is gluten, which has very poor water - solubility under neutral conditions and can only be dissolved by adding a large amount of alkaline agents, and this dissolution is obtained by breaking the molecular chain of gluten. If the distillers' grains protein sizing solution is adjusted to medium - strong alkalinity for sizing the yarn, first, it will greatly reduce the molecular weight of the protein, damage the cohesion of the protein, and have an adverse impact on its sizing performance; second, the alkaline sizing solution will cause serious damage to some alkali - sensitive fiber yarns (such as wool and silk).

[0006] In view of the above problems, it is necessary to develop a simple and easy process method to efficiently extract the components (such as starch and protein) in distillers' grains that can be used as textile sizing agents. At the same time, on the basis of not destroying the molecular structure of the distillers' grains extract, make it undergo graft polymerization reaction with hydrophilic vinyl monomers, introduce hydrophilic grafted branches on the molecular main chain of the distillers' grains extract, improve the water - solubility of distillers' grains starch and endow the distillers' grains protein with water - solubility under neutral conditions, and realize the resource - based and high - value utilization of distillers' grains in the field of textile sizing agents. Summary of the Invention

[0007] The present invention provides a preparation method of a graft-modified distiller's grains textile sizing agent and a graft-modified distiller's grains textile sizing agent with good water solubility under neutral conditions prepared by this method.

[0008] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0009] A preparation method of a graft-modified distiller's grains textile sizing agent includes the following steps: Select a dilute alkali solution to dissolve the effective components for textile sizing agent in distiller's grains at 60-75°C, filter to remove solid impurities, acidify the protein in the solution, and then dialyze, remove impurities, and freeze-dry to obtain a distiller's grains extract for graft polymerization modification; thereafter, under the initiation of an initiator, graft a certain amount of hydrophilic vinyl monomer onto the molecular chain of the distiller's grains extract to prepare a graft-modified distiller's grains textile sizing agent.

[0010] A preparation method of a graft-modified distiller's grains textile sizing agent is specifically as follows:

[0011] (1) Bake the distiller's grains raw material to absolute dryness, grind it into powder, and sieve it. The particle size of the distiller's grains powder is between 50 and 300 meshes; use distilled water as the reaction medium, prepare a suspension with a mass percentage of 10%-20% of the ground distiller's grains powder, under mechanical stirring, add NaOH to the suspension, and the mass ratio of NaOH to distiller's grains powder is 1:10-1:15 (dilute alkali solution), heat up to 60-80°C, stir for 1-4 hours at this temperature, and then filter to remove solid impurities to obtain a distiller's grains extract solution;

[0012] (2) Drop dilute hydrochloric acid into the distiller's grains extract solution obtained in step (1) until the pH value is 4.0-4.5, so that the protein in the extract solution gradually precipitates to form a paste. Place this paste in a dialysis bag and dialyze it with distilled water at room temperature for 24-48 hours. After the dialyzed product is quickly frozen below -40°C, freeze-dry it to obtain a purified distiller's grains extract;

[0013] (3) Add distilled water to prepare a suspension with a mass percentage of 5%-15% of the purified distiller's grains extract obtained in step (2). Under the protection of nitrogen, simultaneously add a hydrophilic vinyl monomer and an initiator for graft polymerization reaction. Stir and react at 30-50°C for 8-12 hours, then add a certain mass of terminator, continue to stir for 10-20 minutes to terminate the reaction, and obtain a graft-modified distiller's grains sizing agent after filtration, washing, and drying.

[0014] In step (2), the concentration of the dilute hydrochloric acid is 2-4 mol / L; the cut-off molecular weight of the dialysis bag is 8000.

[0015] In step (3), the initiator includes K 2S 2 O 8 and NaHSO 3 .

[0016] The molar ratio of the K 2 S 2 O 8 to NaHSO 3 is 1:1.5 to 1:2.0, and the concentration of the K 2 S 2 O 8 in the purified distiller's grains extract suspension is 0.2 to 0.4 mol / L.

[0017] In the step (3), the hydrophilic vinyl monomer is one or more of acrylic acid, methacrylic acid or itaconic acid (this part only selects the preferred scheme), and the mass percentage of the hydrophilic vinyl monomer to the purified distiller's grains extract is 40% to 140%.

[0018] In the step (3), the terminator is hydroquinone.

[0019] In the step (3), the mass ratio of hydroquinone to the purified distiller's grains extract is 1:2500 to 1:5000.

[0020] The distiller's grains extract always remains in a particulate state in the step (3) and in the finished product.

[0021] A graft-modified distiller's grains textile sizing agent prepared by the above preparation method.

[0022] The graft-modified distiller's grains sizing agent prepared by the method of the present invention has good water solubility under neutral conditions (pH 6.5 - 7.5), can significantly improve the use performance of the sizing agent and protect the main sizing objects - natural fiber yarns such as wool and silk from damage by alkali agents, and effectively realizes the resource utilization and high-value utilization of the by-product distiller's grains in the brewing industry.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention can integrally extract the effective components (such as starch and protein) in the distiller's grains that can be used as textile sizing agents, and has low requirements for the distiller's grains raw materials used in the graft polymerization reaction, without chemical pretreatment, the process is simple, and the complex processes such as introducing double bonds into the distiller's grains raw material molecules and separately extracting distiller's grains starch and distiller's grains protein are avoided.

[0025] (2) The present invention uses a combined treatment of suction filtration - dialysis to remove impurities and purify distiller's grains, thoroughly removing the inherent impurities (such as holocellulose, lignin, ash) in the distiller's grains raw materials and the impurities (such as sodium chloride) generated during the extraction of the effective components of distiller's grains, greatly improving the product purity of the distiller's grains extract. The present invention uses a method of rapidly freezing the product after dialysis at ultra - low temperature (below - 40 °C), effectively avoiding the problem that the starch component in the distiller's grains extract is prone to aging and resulting in impaired water solubility in a general low - temperature environment (-20 - 4 °C) for a long time.

[0026] (3) The present invention uses a K 2 S 2 O 8 -NaHSO 3 redox system to initiate the graft polymerization reaction of the distiller's grains extract and hydrophilic vinyl monomers. The required reaction activation energy is low, and the polymerization can be initiated at a lower temperature (30 - 50 °C), which not only reduces energy consumption but also avoids the problem of most of the starch in the distiller's grains dissolving in water, facilitating the collection of the graft - modified distiller's grains product.

[0027] (4) By graft - polymerizing and modifying the distiller's grains extract, the present invention introduces hydrophilic branches onto the macromolecular main chain of the distiller's grains extract, which not only effectively improves the water solubility of the distiller's grains starch but also endows the distiller's grains protein with good water solubility under neutral conditions, laying a foundation for the use of the distiller's grains extract as a textile sizing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is the infrared spectrum of the unmodified yellow rice wine distiller's grains extract (0#) and the graft - modified distiller's grains (1# - 3#) (Note: The grafting rates of 1# - 3# are 60.5%, 55.2%, 64.4% respectively, and the same applies to the following figures and tables).

[0029] Figure 2 FIG. is the scanning electron microscope photos of the unmodified yellow rice wine distiller's grains extract 0# (a), and the graft - modified distiller's grains 1# - 3# (b - d) (Magnification: 300). DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will be further described below in conjunction with specific embodiments. The following are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

[0031] Example 1

[0032] In this example, the distiller's grains are from a yellow rice wine production factory in Zhejiang that mainly uses glutinous rice as raw material. The specific implementation steps include:

[0033] (1) After drying the distillers grains raw material to absolute dryness, grind it into powder and sieve it. The particle size of the distillers grains powder is between 200 meshes. Using distilled water as the reaction medium, prepare a suspension with a mass percentage of 10% of the ground distillers grains powder. Under mechanical stirring conditions, add NaOH with a mass ratio of 1:10 to the distillers grains powder to the suspension, heat it to 70 °C, and stir for 2 h at this temperature. Then, filter to remove solid impurities to obtain the distillers grains extract solution;

[0034] (2) Add 2 mol / L dilute hydrochloric acid dropwise to the distillers grains extract solution obtained in step (1) until the pH value reaches 4.0, so that the protein in the extract solution gradually precipitates to form a paste. Place this paste in a dialysis bag (the cut-off molecular weight of the dialysis bag is 8000), and dialyze it with distilled water at room temperature for 24 h. Place the dialyzed product in a ultra-low temperature refrigerator and quickly freeze it at -40 °C, and then freeze-dry it to obtain the purified distillers grains extract;

[0035] (3) Add distilled water to prepare a 5% suspension of the purified distillers grains extract obtained in step (2). Under the protection of nitrogen, simultaneously add monomer acrylic acid, initiator K 2 S 2 O 8 and NaHSO 3 to carry out graft polymerization reaction. The molar ratio of K 2 S 2 O 8 to NaHSO 3 is 1:1.5. The concentration of K 2 S 2 O 8 in the purified distillers grains extract suspension is 0.2 mol / L. The mass percentage of acrylic acid to the purified distillers grains extract is 85%. After stirring and reacting at 50 °C for 8 h, add hydroquinone as a terminator with a mass ratio of 1:5000 to the purified distillers grains extract, and continue to stir for 10 min to terminate the reaction. After filtration, washing and drying, the graft-modified distillers grains slurry 1# is prepared.

[0036] Example 2

[0037] In this example, the distillers grains are from a liquor production factory in Hebei that mainly uses corn as raw material. The specific implementation steps include:

[0038] (1) After drying the distillers grains raw material to absolute dryness, grind it into powder and sieve it. The particle size of the distillers grains powder is between 200 meshes. Using distilled water as the reaction medium, prepare a suspension with a mass percentage of 15% of the ground distillers grains powder. Under mechanical stirring conditions, add NaOH with a mass ratio of 1:12.5 to the distillers grains powder to the suspension, heat it to 75 °C, and stir for 3 h at this temperature. Then, filter to remove solid impurities to obtain the distillers grains extract solution;

[0039] (2) Add 3 mol / L dilute hydrochloric acid dropwise to the distillers' grains extract solution obtained in step (1) until the pH value reaches 4.0, so that the proteins in the extract solution gradually precipitate to form a paste. Place this paste in a dialysis bag (the cut-off molecular weight of the dialysis bag is 8000), dialyze it with distilled water at room temperature for 36 h, place the dialyzed product in a ultra-low temperature refrigerator, quickly freeze it at -40 °C, and then freeze-dry it to obtain purified distillers' grains extract;

[0040] (3) Add distilled water to make the purified distillers' grains extract obtained in step (2) into a 10% suspension by mass percentage. Under the protection of nitrogen, simultaneously add monomer methacrylic acid, initiator K 2 S 2 O 8 and NaHSO 3 to carry out graft polymerization reaction. The molar ratio of K 2 S 2 O 8 to NaHSO 3 is 1:1.5, and the concentration of K 2 S 2 O 8 in the purified distillers' grains extract suspension is 0.3 mol / L. The mass percentage of methacrylic acid to the purified distillers' grains extract is 110%. After stirring and reacting at 50 °C for 10 h, add hydroquinone as a terminator with a mass ratio of 1:3000 to the purified distillers' grains extract, and continue stirring for 15 min to terminate the reaction. After filtration, washing and drying, graft-modified distillers' grains slurry 2# is prepared.

[0041] Example 3

[0042] In this example, the distillers' grains are from a beer manufacturer in Zhejiang that mainly uses barley as raw material. The specific implementation steps include:

[0043] (1) Dry the distillers' grains raw material to absolute dryness, grind it into powder, and sieve it. The particle size of the distillers' grains powder is between 200 meshes. Use distilled water as the reaction medium, and make the ground distillers' grains powder into a 20% suspension by mass percentage. Under the condition of mechanical stirring, add NaOH with a mass ratio of 1:15 to the distillers' grains powder to the suspension, raise the temperature to 65 °C, stir at this temperature for 4 h, and then filter to remove solid impurities to obtain the distillers' grains extract solution;

[0044] (2) Add 2 mol / L dilute hydrochloric acid dropwise to the distillers' grains extract solution obtained in step (1) until the pH value reaches 4.0, so that the proteins in the extract solution gradually precipitate to form a paste. Place this paste in a dialysis bag (the cut-off molecular weight of the dialysis bag is 8000), dialyze it with distilled water at room temperature for 48 h, place the dialyzed product in a ultra-low temperature refrigerator, quickly freeze it at -40 °C, and then freeze-dry it to obtain purified distillers' grains extract;

[0045] (3) Add distilled water to the purified distiller's grains extract obtained in step (2) to prepare a 15% suspension by mass percentage. Under the protection of nitrogen, simultaneously add monomer itaconic acid, initiator K 2 S 2 O 8 and NaHSO 3 to carry out graft polymerization reaction. The molar ratio of K 2 S 2 O 8 to NaHSO 3 is 1:2.0. The concentration of K 2 S 2 O 8 in the purified distiller's grains extract suspension is 0.2 mol / L. The mass percentage of itaconic acid to the purified distiller's grains extract is 140%. After stirring and reacting at 50 °C for 12 h, add hydroquinone as a terminator with a mass ratio of 1:5000 to the purified distiller's grains extract, and continue stirring for 20 min to terminate the reaction. After filtration, washing, and drying, graft-modified distiller's grains slurry 3# is prepared.

[0046] Detect the water solubility of the graft-modified distiller's grains slurries prepared in Examples 1 to 3 under neutral conditions and their stability after one week. The results are shown in Table 1.

[0047] Table 1 Water solubility and stability of unmodified yellow rice wine distiller's grains extract (0#) and different graft-modified distiller's grains slurries (1# - 3#)

[0048] Distillers grains sample number Visual water solubility Water solubility stability 0# Partially dissolved A large amount of precipitation appears 1# Completely dissolved No precipitation appears 2# Completely dissolved A little precipitation appears 3# Completely dissolved No precipitation appears

[0049] Note: The mass percentage of distiller's grains in the dispersion / solution is 6%, the dissolution temperature is 65 °C. After the distiller's grains are partially / fully dissolved, stop heating, and place the sample at room temperature to observe the water solubility stability after one week.

[0050] Detect the adhesion performance of a certain oxidized corn starch, a certain gelatin protein slurry purchased on the market, and the graft-modified distiller's grains slurries prepared in Examples 1 to 3 to wool fibers. The results are shown in Table 2.

[0051] Table 2 Adhesion performance of unmodified yellow rice wine distiller's grains extract (0#), different graft-modified distiller's grains slurries (1# - 3#), and two common starch and protein slurries to wool fibers

[0052] Slurry type Breaking strength (N / 1000tex) Elongation at break (%) Work of rupture (J / 1000tex) 0# 3.66 3.03 0.004 1# 16.82 5.62 0.035 2# 12.35 5.25 0.024 3# 18.12 6.16 0.041 Oxidized corn starch 11.20 4.83 0.020 Gelatin protein 10.88 5.51 0.023

[0053] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing grafted modified distiller's grains textile pulp, characterized in that: The following steps are involved: A dilute alkaline solution is selected to dissolve the effective ingredients used for textile pulp in the wine lees at 60-75°C, and after filtration to remove solid impurities and acid precipitation of protein in the solution, the wine lees extract for graft polymerization modification is obtained by dialysis, impurity removal and cold drying; then, under the initiation of an initiator, a hydrophilic vinyl monomer is grafted onto the molecular chain of the wine lees extract to obtain a grafted modified wine lees textile pulp.

2. The method for preparing a grafted modified distiller's grains textile pulp according to claim 1, characterized in that: The specific steps are as follows: (1) Dry the vinasse raw material to absolute dryness, grind it into powder, and sieve it. The particle size of the vinasse powder is between 50 and 300 meshes. Use distilled water as a reaction medium to prepare a suspension with a mass percentage of 10% to 20% of the ground vinasse powder. Under mechanical stirring conditions, add NaOH to the suspension. The mass ratio of NaOH to vinasse powder is 1:10 to 1:

15. Heat the suspension to 60 to 80° C., stir at this temperature for 1 to 4 hours, and then filter to remove solid impurities to obtain a vinasse extract solution. (2) adding dilute hydrochloric acid dropwise to the vinasse extract solution obtained in step (1) until the pH value is 4.0-4.5, so that the protein in the extract solution is gradually precipitated to form a slurry, placing the slurry in a dialysis bag, dialyzing it with distilled water at room temperature for 24-48 hours, and rapidly freezing the dialyzed product at below -40°C, and freeze-drying it to obtain a purified vinasse extract; (3) adding distilled water to prepare a suspension having a mass percentage of 5% to 15% of the purified vinasse extract obtained in step (2); adding a hydrophilic vinyl monomer and an initiator simultaneously under the protection of nitrogen to carry out a graft polymerization reaction; stirring the reaction at 30 to 50° C. for 8 to 12 hours; adding a terminator; continuing stirring for 10 to 20 minutes to terminate the reaction; filtering, washing and drying to obtain a grafted modified vinasse slurry.

3. The method for preparing a grafted modified distiller's grains textile pulp according to claim 2, characterized in that: In the step (2), the concentration of the dilute hydrochloric acid is 2-4 mol / L; and the molecular weight cut-off of the dialysis bag is 8000.

4. The method for preparing a grafted modified distiller's grains textile pulp according to claim 2, characterized in that: In the step (3), the initiator includes K2S2O8 and NaHSO3.

5. The method for preparing a grafted modified distiller's grains textile pulp according to claim 4, characterized in that: The molar ratio of K2S2O8 to NaHSO3 is 1:1.5-1:2.0, and the concentration of K2S2O8 in the purified vinasse extract suspension is 0.2-0.4 mol / L.

6. The method for preparing a grafted modified distiller's grains textile pulp according to claim 2, characterized in that: In the step (3), the hydrophilic vinyl monomer is one or more of acrylic acid, methacrylic acid or itaconic acid, and the mass percentage of the hydrophilic vinyl monomer to the purified vinasse extract is 40% to 140%.

7. The method for preparing a grafted modified distiller's grains textile pulp according to claim 2, characterized in that: In the step (3), the terminator is hydroquinone.

8. The method for preparing a grafted modified distiller's grains textile pulp according to claim 7, characterized in that: In the step (3), the mass ratio of hydroquinone to purified vinasse extract is 1:2500 to 1:5000.

9. The method for preparing a grafted modified distiller's grains textile pulp according to claim 2, characterized in that: The vinasse extract remains in a granular state throughout step (3) and in the finished product.

10. A grafted modified distiller's grains textile pulp prepared by the preparation method according to any one of claims 1 to 9.

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