Preparation method and application of a bio-based plastic starch slurry with medium-temperature water solubility

Abstract

This invention discloses a method for preparing and applying a bio-based plastic starch slurry with medium-temperature water solubility, belonging to the field of textile manufacturing technology. The invention uses native starch as raw material, utilizes amylase to hydrolyze starch to prepare branched-limit dextrin, and uses this as a plasticizer for the starch slurry. Then, amphoteric starch is prepared by grafting in a two-step process at low temperature. Finally, an ethanol-alkali method is used to treat the starch to obtain a medium-temperature water-soluble amphoteric starch slurry. The preparation, boiling, and sizing processes of this slurry all occur at temperatures not exceeding 70℃, achieving medium-low temperatures throughout the entire process. This significantly reduces energy consumption while ensuring the sizing yarn performance meets weaving requirements. Furthermore, the prepared bio-based plastic starch slurry with medium-temperature water solubility exhibits excellent sizing performance, and the sized glass fiber warp yarns possess high bundle strength, high abrasion resistance, excellent mechanical properties, and excellent softness.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a bio-based plastic starch slurry with medium-temperature water solubility, belonging to the field of textile manufacturing technology. Background Technology

[0002] In the actual weaving process of glass fiber, breakage is common due to external mechanical forces, resulting in defects on the fabric surface and affecting product quality. Therefore, to improve the physical and mechanical properties of glass fiber warp yarns and effectively reduce yarn breakage, sizing is necessary. The choice of sizing agent has a significant impact on improving yarn quality. Excellent textile sizing agents should possess the following characteristics: suitable viscosity, good liquid-phase dispersion stability, excellent adhesion, excellent film-forming properties, and ease of desizing with simple wastewater treatment. Currently, commonly used sizing agents for glass fiber yarns are mainly divided into polyvinyl alcohol (PVA), acrylic, and starch-based agents. PVA sizing agents, due to their excellent sizing performance, were once called "ideal sizing agents," but their high COD value places a significant burden on the environment. Acrylic acid sizing agents are more environmentally friendly, but their composition is complex, their quality varies, and they are expensive. Starch has the advantages of being inexpensive, readily available, and easily degradable, but it is poorly soluble in water, has poor film-forming properties, and produces brittle and hard films.

[0003] Traditional starch slurries suffer from numerous problems, including high-temperature sizing, viscosity fluctuations, severe pollution, and high energy consumption. To address these issues, existing technologies have made improvements. For example, Chinese Patent CN112111018A discloses a method for preparing a medium-temperature starch slurry. This invention introduces amphiphilic functional groups to plasticize the starch adhesive layer through steric hindrance. Simultaneously, the introduction of hydrophilic and hydrophobic functional groups reduces the surface tension of the starch slurry, solving the problems of poor wetting and spreading between the starch interface layer and fibers. Another example is Chinese Patent CN116240724A, which discloses a method for preparing a multi-branched cationic starch slurry for medium- and low-temperature warp sizing. Through hydrolysis, cationic etherification, and multi-branching, a highly substituted multi-branched cationic starch slurry is obtained. Both the invention and application processes can be carried out in medium- and low-temperature environments, effectively reducing energy consumption, improving the utilization rate of etherifying agents, and significantly improving the working environment for workers, thus meeting the requirements of energy conservation, environmental protection, and sustainable development. For example, Chinese patent CN106319960B discloses a sizing formula for medium-temperature sizing of pure cotton warp yarn, which includes medium-temperature soluble starch and polyacrylic acid sizing agent. This invention uses the blending of medium-temperature soluble starch and polyacrylic acid sizing agent to adjust the sizing process so that the sized pure cotton yarn meets weaving requirements. Because of its simple formula and easy sizing process, it significantly improves the working environment of workers in the sizing workshop and reduces enterprise costs. However, patent CN112111018A uses calcium oxide and phosphate substances in the starch preparation process. If these substances are not completely removed during industrial production, it will lead to an increase in ash residue when using the calcination method for desizing, resulting in defects and yellow spots on the glass fiber. Patent CN106319960B uses polyacrylic acid sizing agents to blend with starch. However, due to the complex composition, poor quality control, and high price of polyacrylic acid sizing agents, it cannot completely replace PVA sizing agents in glass fiber sizing and has certain limitations. Patent CN116240724A, due to the multibranching of starch, leads to a decrease in starch hydrophilicity and polarity. When the starch sizing agent is applied, it cannot form a strong hydroxyl force with the silanol groups on the surface of the glass fiber, which weakens the affinity between the starch sizing agent and the glass fiber to a certain extent. Summary of the Invention

[0004] [Technical Issues]

[0005] Currently, most existing medium and low temperature starch sizing agents are developed based on traditional yarns, without considering the properties of glass fiber itself and the requirements for sizing and desizing. They have certain defects in terms of yarn bundle properties, yarn abrasion resistance, and ash residue after desizing. For example, glass fiber yarn has poor bundle properties, low abrasion resistance, and excessive ash residue, leaving yellow spots.

[0006] [Technical Solution]

[0007] To address the aforementioned issues, this invention designs and develops a plastic starch slurry with medium-temperature water solubility. Traditional starch slurries, when used for sizing glass fiber warp yarns, fail to effectively improve the abrasion resistance of the yarns due to the inherent brittleness of the starch film. The addition of a plasticizer prepared from enzymatically hydrolyzed starch enhances the plasticity of the starch film. Simultaneously, the high viscosity of the slurry makes it difficult to penetrate between the fibers of the glass fiber warp yarns, resulting in surface adhesion. The introduction of amphiphilic groups reduces the surface tension of the slurry, allowing it to further penetrate the yarn and improve its bundle structure. Finally, the modified starch is treated using an ethanol-alkali method, enabling it to dissolve and gelatinize at medium temperatures, thus reducing energy consumption during the slurry preparation process. The medium-temperature water-soluble plastic starch slurry prepared by this invention aligns with the principles of green development and meets the requirements for subsequent weaving and reinforcement of glass fiber yarns.

[0008] To achieve the above objectives, the following technical solution is provided:

[0009] A method for preparing a bio-based plastic starch slurry with medium-temperature water solubility, the method comprising the following steps:

[0010] (1) Preparation of starch dextrin: The gelatinized starch was kept in a water bath at 50-60℃ and the pH was adjusted to 6 with acetate buffer. α-amylase was added to react. After the reaction, the pH of the system was adjusted to 5.5 and the temperature was lowered to 45-55℃. β-amylase was added to react. After the reaction, the enzyme was inactivated. The precipitate was separated by ethanol precipitation and centrifuged. The precipitate was collected and freeze-dried to obtain starch dextrin A.

[0011] (2) Crosslinking modification: The original starch is dispersed in deionized water to prepare starch milk, and then a crosslinking agent is added to the starch milk to react. After the reaction, the pH of the starch milk is neutralized to 7-8, and the starch milk is filtered and washed. Finally, it is dried and ground into powder to obtain modified starch A.

[0012] (3) Cationic modification: The modified starch A obtained in step (2) is dispersed in deionized water to prepare starch milk. The starch milk is placed in a four-necked flask under nitrogen atmosphere, and cationic monomers and catalysts are added to react. After the reaction is completed, the mixture is filtered, washed, dried and ground into powder to obtain modified starch B.

[0013] (4) Preparation of medium-temperature water-soluble starch: Under the conditions of a water bath at 50-60℃, the modified starch B prepared in step (3) is dispersed in an ethanol-water solution with a volume ratio of 1:1 to prepare a starch milk. Then, a sodium hydroxide solution prepared with an ethanol-water solution with a volume ratio of 1:1 is added. After keeping warm, the mixture is centrifuged, the precipitate after centrifugation is washed, and then vacuum dried to obtain medium-temperature water-soluble starch C.

[0014] (5) Slurry preparation: Disperse the medium-temperature water-soluble starch C prepared in step (4) and the starch dextrin A prepared in step (1) in deionized water to prepare starch milk. Place the starch milk in a slurry cooking tank and gelatinize it at 60-70℃ to obtain a bio-based plastic starch slurry with medium-temperature water solubility.

[0015] In one embodiment, the mass fraction of the gelatinized starch in step (1) is 40-45%.

[0016] In one embodiment, the reaction time for adding α-amylase in step (1) is 24 to 36 hours.

[0017] In one embodiment, the reaction time for adding β-amylase in step (1) is 24 to 48 hours.

[0018] In one embodiment, the original starch in step (2) includes one or more of corn starch, cassava starch, potato starch, sweet potato starch, and wheat starch.

[0019] In one embodiment, the crosslinking agent in step (2) includes one or more of epichlorohydrin, glyceryl diglycidyl ether, ethylene glycol diglycidyl ether, glycidyl methacrylate, 1,4-butanediol diglycidyl ether, ethoxyepoxychloropropane, and acrylamide.

[0020] In one embodiment, the mass fraction of starch in the reaction system of step (2) is 30-50%, the mass fraction of crosslinking agent is 0.5-2%, and the reaction time is 4-6 hours.

[0021] In one embodiment, NaCl solution and NaOH solution are also added to the reaction system in step (2), wherein the mass fraction of NaCl solution is 1%, the mass fraction of NaOH solution is 15%, and the volume ratio of NaCl solution to NaOH solution is 2:1.

[0022] In one embodiment, the mass fraction of starch milk in the reaction system of step (3) is 30-60%.

[0023] In one embodiment, the cationic monomer in step (3) includes one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloylchloropropyltrimethylammonium chloride, methacryloyloxypropyldimethylethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride, methacryloyloxyethyldimethylphenylethylammonium chloride, acryloyloxyethyltrimethylmethylammonium chloride, and methacryloyloxyethyldimethylalkylammonium chloride.

[0024] In one embodiment, the catalyst in step (3) is one or more of the following: cerium ammonium nitrate, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, tert-butyl peroxide, dicumyl peroxide, dibenzoyl peroxide, azobisisobutyronitrile (AIBN), sodium hydroxide, potassium hydroxide, ferric chloride, zinc chloride, and potassium permanganate.

[0025] In one embodiment, the mass fraction of the cationic monomer in step (3) is 1-2%.

[0026] In one embodiment, the mass fraction of the catalyst in step (3) is 0.1-0.5%.

[0027] In one embodiment, the reaction time in step (3) is 4 to 6 hours.

[0028] In one embodiment, the starch milk in step (4) has a mass fraction of 30-60%.

[0029] In one embodiment, the sodium hydroxide solution in step (4) has a mass fraction of 1-5%.

[0030] In one embodiment, the heat preservation time in step (4) is 0.5 to 2 hours.

[0031] In one embodiment, the mass ratio of the medium-temperature water-soluble starch C and starch dextrin A in step (5) is 8 to 12:1.

[0032] In one embodiment, the mass fraction of the starch milk in step (5) is 2-6%.

[0033] The present invention also provides a bio-based plastic starch slurry with medium-temperature water solubility for sizing glass fiber warp yarns prepared by the above-described method.

[0034] The present invention also provides the application of the bio-based plastic starch sizing agent with medium-temperature water solubility in glass fiber warp sizing in glass fiber yarn sizing.

[0035] Beneficial effects:

[0036] This invention prepares a green sizing agent that dissolves at medium temperatures, while significantly improving the bundle bonding and abrasion resistance of glass fibers. Using corn starch as raw material, branched-limit dextrin is prepared by amylase hydrolysis of starch and used as a plasticizer in the starch sizing agent. Then, amphoteric starch is prepared by a two-step grafting process at low temperatures. Finally, the sizing agent is treated with an ethanol-alkali method to obtain a medium-temperature water-soluble amphoteric starch sizing agent. The preparation, boiling, conditioning, and sizing processes of this sizing agent all operate at temperatures not exceeding 70℃, achieving medium-low temperatures throughout the entire process, greatly reducing energy consumption while ensuring the sizing properties meet weaving requirements. Compared with existing technologies, it has the following advantages:

[0037] (1) The bio-based plastic starch slurry with medium-temperature water solubility prepared by the present invention has excellent sizing performance; the glass fiber warp yarn after sizing has high bundle strength, high wear resistance, excellent mechanical properties and excellent softness.

[0038] (2) The present invention uses a two-step grafting modification of starch slurry to effectively improve the permeability of starch slurry to glass fiber and improve the bundle properties of glass fiber warp yarn after sizing. At the same time, starch dextrin, as a plasticizer, improves the softness and wear resistance of glass fiber warp yarn after sizing while ensuring good compatibility with starch. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The specific embodiments described below further illustrate the present invention.

[0040] Example 1

[0041] A method for preparing a bio-based plastic starch slurry with medium-temperature water solubility includes the following steps:

[0042] (1) Preparation of starch dextrin: The gelatinized starch milk with a mass fraction of 40% was kept in a water bath at 60℃ and the pH was adjusted to 6 with acetate buffer. α-amylase was added and the reaction was carried out for 24 h. The pH of the system was adjusted to 5.5 and the temperature was lowered to 55℃. β-amylase was added and the reaction was carried out for 48 h. After the reaction was completed, the enzyme activity was inactivated by boiling. The precipitate was separated by ethanol precipitation and centrifuged. The precipitate was collected and freeze-dried. The obtained starch dextrin A was stored for later use.

[0043] (2) Crosslinking modification: Corn starch was dispersed in deionized water to prepare starch milk. 10 ml of 1% NaCl solution was added, followed by 5 ml of 15% NaOH solution. After stirring for 0.5 h, a certain amount of epichlorohydrin was added dropwise to the starch milk to carry out the reaction. In the reaction system, the mass fraction of starch was 40% and the mass fraction of epichlorohydrin was 1%. After 4 h, the reaction was completed. The starch milk was neutralized with 0.1 mol / L acetate buffer to pH 7. The starch milk was then filtered and washed, and finally dried and ground into powder to obtain modified starch A.

[0044] (3) Cationic modification: The modified starch A prepared in step (2) is dispersed in deionized water to prepare a starch milk with a certain content. The starch milk is placed in a four-necked flask under nitrogen atmosphere. The water bath temperature is adjusted to 50°C. The cationic monomer methacryloyloxyethyltrimethylammonium chloride and the catalyst cerium ammonium nitrate are added to carry out the reaction. In the reaction system, the mass fraction of starch is 40%, the mass fraction of methacryloyloxyethyltrimethylammonium chloride is 1%, and the mass fraction of cerium ammonium nitrate is 0.2%. After 4 hours, the reaction is completed. The starch is filtered, washed, dried and ground into powder to obtain modified starch B.

[0045] (4) Preparation of medium-temperature water-soluble starch: Under the condition of 60℃ water bath, the modified starch B prepared in step (3) is dispersed in an ethanol-water solution with a volume ratio of 1:1 to prepare a starch milk with a mass fraction of 40%. Then, 10 ml of sodium hydroxide solution with a mass fraction of 5% prepared in an ethanol-water solution with a ratio of 1:1 is added. After keeping warm for 0.5 h, the precipitate after centrifugation is washed and then vacuum dried to obtain medium-temperature water-soluble starch C.

[0046] (5) Slurry preparation: Disperse the medium-temperature water-soluble starch C prepared in step (4) and the starch dextrin A prepared in step (1) in deionized water at a mass ratio of 10:1 to prepare a starch milk with a mass fraction of 6%. Place the starch milk in a slurry cooking tank and gelatinize it at 70°C for 1 hour to obtain a medium-temperature water-soluble plastic slurry for sizing glass fiber warp yarns.

[0047] Example 2

[0048] A method for preparing a medium-temperature water-soluble bio-based plastic starch slurry, referring to Example 1, differs only in the following steps: (3) cationic modification: the modified starch A prepared in step (2) is dispersed in deionized water to prepare a starch slurry with a certain content. The starch slurry is placed in a four-necked flask under nitrogen atmosphere, the water bath temperature is adjusted to 50°C, and the cationic monomer 3-chloro-2-hydroxypropyltrimethylammonium chloride and the catalyst sodium hydroxide are added for reaction. In the reaction system, the mass fraction of starch is 40%, the mass fraction of 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1%, and the pH of the system solution is adjusted to 11 by a 2% NaOH solution, which also serves as a catalyst. After the reaction is completed in 4 hours, the mixture is filtered, washed, dried, and ground into powder to obtain modified starch B. Other parameters and conditions are the same as in Example 1.

[0049] Example 3

[0050] A method for preparing a bio-based plastic starch slurry with medium-temperature water solubility is described in Example 1, with the only difference being: Step (2) crosslinking modification: Corn starch is dispersed in deionized water to prepare a starch slurry, 10 ml of 1% NaCl solution is added, and then 5 ml of 15% NaOH solution is added to the starch slurry. After stirring for 0.5 h, a certain amount of acrylonitrile is added dropwise to the starch slurry for reaction. In the reaction system, the mass fraction of starch is 40% and the mass fraction of acrylonitrile is 1%. After 4 h, the reaction is completed. The starch slurry is neutralized with 0.1 mol / L acetate buffer solution at pH 7, and the starch slurry is filtered and washed. Finally, it is dried and ground into powder to obtain modified starch A. Other parameters and conditions are the same as in Example 1.

[0051] Example 4

[0052] A method for preparing a bio-based plastic starch slurry with medium-temperature water solubility is described in Example 1, with the only difference being: Step (2) crosslinking modification: Corn starch is dispersed in deionized water to prepare a starch slurry, 10 ml of 1% NaCl solution is added, and then 5 ml of 15% NaOH solution is added to the starch slurry. After stirring for 0.5 h, a certain amount of diene is added dropwise to the starch slurry for reaction. In the reaction system, the mass fraction of starch is 40% and the mass fraction of diene is 1%. The reaction is completed after 2 h. The starch slurry is neutralized with 0.1 mol / L acetate buffer solution to a pH of 7, and the starch slurry is filtered and washed. Finally, it is dried and ground into powder to obtain modified starch A. Other parameters and conditions are the same as in Example 1.

[0053] Example 5

[0054] A method for preparing a medium-temperature water-soluble bio-based plastic starch slurry, referring to Example 1, differs only in the following steps: (3) cationic modification: the modified starch A prepared in step (2) is dispersed in deionized water to prepare a starch slurry with a certain content. The starch slurry is placed in a four-necked flask under nitrogen atmosphere. The water bath temperature is adjusted to 50°C. The cationic monomer 2-acryloyloxytrimethylammonium chloride and the catalyst ammonium persulfate are added to carry out the reaction. In the reaction system, the mass fraction of starch is 40%, the mass fraction of 2-acryloyloxytrimethylammonium chloride is 1%, and the mass fraction of ammonium persulfate is 0.1%. After 4 hours, the reaction is completed. The mixture is filtered, washed, dried, and ground into powder to obtain modified starch B. Other parameters and conditions are the same as in Example 1.

[0055] Comparative Example 1

[0056] A method for preparing a medium-temperature water-soluble plastic starch slurry, referring to Example 1, the only difference being that in step (2), trimethylolpropane acrylate is used as a crosslinking agent, and other parameters and conditions are the same as in Example 1.

[0057] Comparative Example 2

[0058] A method for preparing a medium-temperature water-soluble plastic starch slurry, referring to Example 1, the only difference being that in step (3), acryloyloxypropyltrimethylammonium chloride is used as the cationic monomer, and other parameters and conditions are the same as in Example 1.

[0059] Comparative Example 3

[0060] A method for preparing a medium-temperature water-soluble plastic starch slurry, referring to Example 1, the only difference being that starch dextrin is not added in step (5), and all other parameters and conditions are the same as in Example 1.

[0061] Comparative Example 4

[0062] A method for preparing a medium-temperature water-soluble plastic starch slurry, referring to Example 1, except that step (4) is omitted, while other parameters and conditions are the same as in Example 1.

[0063] Comparative Example 5

[0064] Referring to Example 1 disclosed in CN112111018A, 3-chloro-2-hydroxypropyltrimethylammonium chloride was used as a cationic monomer and itaconic anhydride was used as a crosslinking agent for amphiphilic modification. Finally, it was treated with sodium polyphosphate to obtain a medium-temperature starch slurry.

[0065] Example 6

[0066] The application of a medium-temperature water-soluble plastic starch slurry prepared in Examples 1-5 and Comparative Examples 1-5 in the sizing of glass fiber yarn. The glass fiber yarn used was 24-count, 1-ply alkali-free waxed glass fiber yarn provided by Yushun Textile Co., Ltd. The sizing process included the following steps:

[0067] The sizing test was conducted using a GA392 electronic single yarn sizing machine. The temperature of the sizing tank was set to 70℃. Medium-temperature water-soluble plastic starch sizing material was poured into the sizing tank, and glass fiber yarn was wound onto the sizing machine for sizing. The sizing speed was 20m / min, and the sizing tension was 0.5N. After sizing, the yarn bobbin was removed to obtain the product.

[0068] Results Analysis

[0069] According to the method in Example 6, the medium-temperature water-soluble plastic starch slurry prepared in each example and comparative example was used to sizing glass fiber yarn. The abrasion resistance of the products was tested using an abrasion tester according to standard FZ / T01058—1999 "Test Method for Abrasion Resistance of Yarn - Reciprocating Roller Method", with the number of friction fractures used as the abrasion resistance index. Performance tests were conducted according to GB / T7690.3-2013 "Determination of Breaking Strength and Elongation at Break of Textile Glass Fiber Yarn". The results are summarized in Table 1.

[0070] Table 1. Breaking strength and elongation at break of glass fiber yarn

[0071]

[0072] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing a bio-based plastic starch slurry with medium-temperature water solubility, characterized in that, The method includes the following steps: (1) Preparation of starch dextrin: The gelatinized starch was kept in a water bath at 50~60℃ and the pH was adjusted to 6 with acetate buffer. α-amylase was added to react. After the reaction, the pH of the system was adjusted to 5.5 and the temperature was lowered to 45~55℃. β-amylase was added to react. After the reaction, the enzyme was inactivated. The precipitate was separated by ethanol precipitation and centrifuged. The precipitate was collected and freeze-dried to obtain starch dextrin A. (2) Crosslinking modification: The original starch is dispersed in deionized water to prepare starch milk, and then a crosslinking agent is added to the starch milk to react. After the reaction, the pH of the starch milk is neutralized to 7-8, and the starch milk is filtered and washed. Finally, it is dried and ground into powder to obtain modified starch A; the crosslinking agent is epichlorohydrin. The mass fraction of starch in the reaction system is 30-50%, the mass fraction of cross-linking agent is 0.5-2%, and the reaction time is 4-6 hours. (3) Cationic modification: The modified starch A obtained in step (2) is dispersed in deionized water to prepare starch milk. The starch milk is placed in a four-necked flask under nitrogen atmosphere, and cationic monomer and catalyst are added to react. After the reaction is completed, the mixture is filtered, washed, dried and ground into powder to obtain modified starch B. The cationic monomer includes one or both of 3-chloro-2-hydroxypropyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride; The catalyst is one or both of cerium ammonium nitrate and ammonium persulfate. (4) Preparation of medium-temperature water-soluble starch: Under the conditions of a water bath at 50~60℃, the modified starch B prepared in step (3) is dispersed in an ethanol-water solution with a volume ratio of 1:1 to prepare a starch milk. Then, a sodium hydroxide solution prepared with an ethanol-water solution with a volume ratio of 1:1 is added. After keeping warm, the mixture is centrifuged, the precipitate after centrifugation is washed, and then vacuum dried to obtain medium-temperature water-soluble starch C. (5) Slurry preparation: Disperse the medium-temperature water-soluble starch C prepared in step (4) and the starch dextrin A prepared in step (1) in deionized water to prepare starch milk. Place the starch milk in a slurry cooking tank and gelatinize it at 60~70℃ to obtain a bio-based plastic starch slurry with medium-temperature water solubility. The mass ratio of the medium-temperature water-soluble starch C to starch dextrin A is 8~12:

1.

2. The preparation method according to claim 1, characterized in that, The mass fraction of the gelatinized starch in step (1) is 40-45%.

3. The preparation method according to claim 1, characterized in that, The original starch in step (2) includes one or more of corn starch, cassava starch, potato starch, sweet potato starch, and wheat starch.

4. The preparation method according to claim 1, characterized in that, The mass fraction of the starch milk in step (5) is 2-6%.

5. The bio-based plastic starch slurry with medium-temperature water solubility for sizing glass fiber warp yarns prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the bio-based plastic starch sizing agent with medium-temperature water solubility as described in claim 5 in the sizing of glass fiber warp yarns.

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