Preparation method of a ternary solid-phase esterification composite bio-based modified polyester sizing starch and application thereof

Abstract

This invention discloses a method for preparing a ternary solid-phase esterification composite bio-based modified starch for polyester sizing and its application, belonging to the field of textile processing technology. The preparation of the modified starch for polyester sizing according to this invention includes: uniformly mixing starch and phosphorus oxychloride in water, and acid-hydrolyzing the mixture under water bath conditions; modifying the acid-hydrolyzed starch by mixing itaconic acid and citric acid, and then esterifying it stepwise using a twin-screw extruder; subsequently, adding phytic acid to graft phytic acid phosphate groups onto the starch surface. This modified starch exhibits both excellent sizing and desizing rates, and the resulting sizing film possesses excellent elongation at break and abrasion resistance. Furthermore, the preparation method is simple, the process can be continuous, and the resulting sizing agent is biodegradable, meeting the requirements of green textiles and sustainable development.

Description

Technical Field

[0001] This invention relates to a method for preparing ternary solid-phase esterification composite bio-based modified polyester starch for sizing and its application, belonging to the field of textile processing technology. Background Technology

[0002] As the most consumed synthetic fiber raw material in the modern textile industry, polyester fiber (polyester) dominates many fields such as clothing, home textiles, and industrial textiles due to its excellent mechanical strength, elastic recovery, and dimensional stability. During the weaving process, warp yarns must undergo high-speed stretching, high-frequency bending, and intense mechanical friction. It usually relies heavily on the warp sizing process to build a strong and continuous protective sizing film on the yarn surface to improve its breaking strength and subdue the fuzz, thereby reducing the weaving breakage rate and ensuring stable production with high efficiency and low loss.

[0003] However, polyester macromolecules lack polar functional groups and have high crystallinity, resulting in a highly hydrophobic surface. This inherent interfacial characteristic makes it extremely difficult for traditional natural starch sizing agents to achieve good spreading and wetting on its surface, leading to severely insufficient adsorption and adhesion. Therefore, polyvinyl alcohol and acrylic sizing agents are commonly used in traditional polyester sizing, but these sizing agents require strong alkalis or strong oxidants for desizing, increasing the difficulty of wastewater treatment.

[0004] To address this challenge, developing green and environmentally friendly modified starch slurries to replace petroleum-based synthetic slurries has become an industry consensus. By introducing specific functional groups onto the starch macromolecular backbone, its hydrophilicity / hydrophobicity can be adjusted, and its interfacial compatibility with fibers can be improved. Specifically, esterification modification disrupts the original crystalline structure of starch to enhance the flexibility and desizing ease of the slurry film; simultaneously, the introduction of long carbon linking groups enhances the affinity and adhesion of the slurry to hydrophobic polyester fibers. This dual-group composite modification strategy is considered a representative technical approach that balances "high-performance adsorption" and "green desizing."

[0005] Although some progress has been made in the application of modified starch sizing agents for polyester warp yarns, there are still many technical bottlenecks that need to be addressed: First, the balance mechanism between the adhesion strength and film flexibility of modified starch sizing agents is not yet clear, making it difficult for the sizing agents to simultaneously meet the high strength requirements for warp yarn protection and the flexibility requirements during high-speed weaving; Second, the abrasion resistance of such sizing agents under high-speed weaving conditions is still insufficient, and problems such as film rupture and shedding are prone to occur, affecting weaving stability; Third, the interfacial interaction mechanism between modified starch and polyester fibers has not been clearly elucidated, which restricts the precise optimization of sizing agent modification.

[0006] By comprehensively innovating the structural design and preparation process, the large-scale continuous production of modified starch was achieved while improving reaction efficiency and the uniformity of group distribution. The resulting composite modified starch slurry possesses excellent hydrophilic-hydrophobic dynamic balance, capable of forming a multifunctional protective film on hydrophobic polyester surfaces that combines high adhesion, excellent flexibility, and superb abrasion resistance, and exhibits significant bio-desizing properties. The implementation of this invention not only effectively solves the technical challenges of sizing in high-speed polyester warp weaving, but also has significant theoretical research value and broad industrial application prospects for promoting the transformation of textile sizing towards continuous, green, low-carbon, and sustainable production. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing ternary solid-phase esterification composite bio-based modified starch for polyester sizing and its application. This method is simple, easy to prepare, low in cost, and environmentally friendly. The modified starch prepared has good sizing and desizing rates, and the resulting sizing film has excellent elongation at break, which can significantly improve its adhesion and film-forming properties to hydrophobic polyester fibers, thereby enhancing its abrasion resistance. In addition, it also has good biodegradability, meeting the requirements of green textiles and sustainable development.

[0008] To achieve the above objectives, the following technical solution is provided: The first objective of this invention is to provide a method for preparing ternary solid-phase esterification composite bio-based modified starch for polyester sizing, the method comprising the following steps: (1) Mix starch and phosphorus oxychloride (POCl3) in water until uniform, and modify by acid hydrolysis under water bath conditions to obtain acid hydrolyzed starch (CLS) containing phosphoryl groups. (2) The phosphoryl group-containing acid hydrolyzed starch obtained in step (1) is mixed with ethanol, itaconic acid and citric acid, dried and pulverized to obtain a modifier mixture; (3) The modifier mixture obtained in step (2) is added to a twin-screw extruder for extrusion treatment. The extrudate is washed, filtered, dried and crushed to obtain citric acid-itaconic acid synergistic modified starch (CIS). (4) The citric acid-itaconic acid synergistic modified starch obtained in step (3) is mixed with ethanol and phytic acid, stirred at room temperature, filtered, heated and solidified, and pulverized to obtain phytic acid functionalized citric acid-itaconic acid synergistic modified starch (PA / CIS); that is, the ternary solid-phase esterification composite bio-based modified polyester starch.

[0009] In one embodiment, in step (1), the starch is corn starch or tapioca starch.

[0010] In one embodiment, in step (1), the mass ratio of starch to phosphorus oxychloride is 100~150:1.

[0011] In one embodiment, in step (1), the mass ratio of starch to water is 1 to 5:3; preferably 2:3.

[0012] In one embodiment, in step (1), the water bath conditions are: 40~50 ℃, and the time is 3~5 h.

[0013] In one embodiment, step (1) further includes washing, filtering, drying and pulverizing the acid-modified product.

[0014] In one embodiment, the washing process uses deionized water and ethanol.

[0015] In one embodiment, in step (2), the mass ratio of the phosphoryl group-containing acid-hydrolyzed starch to ethanol is 10:6 to 10:10.

[0016] In one embodiment, in step (2), the mass ratio of the phosphoryl group-containing acid hydrolyzed starch to itaconic acid (IA) is 100:5~10; preferably 100:5~8.

[0017] In one embodiment, in step (2), the mass ratio of the phosphoryl group-containing acid hydrolyzed starch to citric acid (CA) is 100:10.

[0018] In one embodiment, in step (3), the temperatures of the six reaction chambers of the twin-screw extruder are 20~40℃, 40~60℃, 60~80℃, 80~100℃, 100~120℃, and 120~140℃, respectively; preferably 40℃, 60℃, 80℃, 100℃, 120℃, and 135℃.

[0019] In one embodiment, in step (3), the feed rate of the twin-screw extruder is 20~80 g / min.

[0020] In one embodiment, in step (3), the rotational speed of the twin-screw extruder is 60~120 rpm.

[0021] In one embodiment, in step (3), the washing process uses deionized water, ethanol, and acetone.

[0022] In one embodiment, in step (4), the mass ratio of the citric acid-itaconic acid synergistic modified starch to ethanol is 10:8~10.

[0023] In one embodiment, in step (4), the mass ratio of the citric acid-itaconic acid synergistic modified starch to phytic acid (PA) is 100:10.

[0024] In one embodiment, in step (4), the room temperature stirring time is 2 h and the rotation speed is 500 rpm.

[0025] In one embodiment, in step (4), the heating and curing temperature is 60 °C and the time is 4 h.

[0026] In one embodiment, in steps (2) and (4), the ethanol is anhydrous ethanol.

[0027] The second objective of this invention is to provide a ternary solid-phase esterified composite bio-based modified polyester starch prepared by the above-described preparation method.

[0028] The third objective of this invention is to provide an application of the above-mentioned ternary solid-phase esterified composite bio-based modified starch for polyester sizing in polyester sizing.

[0029] The fourth objective of this invention is to provide a method for improving the sizing rate and desizing rate of polyester fabrics, wherein the method uses the aforementioned bio-based modified starch for polyester sizing.

[0030] The fifth objective of this invention is to provide a method for improving the elongation at break and abrasion resistance of polyester sizing films, wherein the method uses the aforementioned bio-based modified starch for polyester sizing to form the film.

[0031] Beneficial effects: This invention provides a method for preparing a ternary solid-phase esterification composite bio-based modified starch for polyester sizing. The method involves sequentially acid-hydrolyzing, itaconic acid, citric acid, and phosphoric acid esterification of starch to construct a starch slurry with specific chemical structure and interfacial properties. This modified starch, by introducing phosphoryl groups to create active sites before esterification, significantly improves its adhesion and film-forming properties to hydrophobic polyester fibers while maintaining its biodegradability. Specific advantages are as follows: 1. On the one hand, the technical problem solved by this invention is to prepare modified starch using a twin-screw extrusion dry method, thereby improving the waste caused by the large amount of water used in the preparation of modified starch; 2. The modified starch prepared by this invention exhibits excellent sizing and desizing rates, with a sizing rate reaching 6.53% and a desizing rate reaching 92.34%. Simultaneously, the formed starch film possesses excellent elongation at break and abrasion resistance; the elongation at break reaches 6.93%, and the abrasion loss is only 0.137 mg·cm⁻¹. -2 ; 3. This invention uses corn starch as the base, which is widely available. Citric acid, itaconic acid, and phytic acid are all renewable biomass resources. The resulting slurry is biodegradable, and at the same time, it avoids the problem of using large amounts of organic solvents in traditional solution modification, which meets the requirements of green textiles and sustainable development. 4. This invention exhibits excellent redispersibility in water, rapid resolubility, and no clumping. It does not require prolonged gelatinization or high-speed stirring during use. The esterification reaction can be controlled stepwise by adjusting parameters such as pH, screw speed, and temperature, and it has good potential for industrial scale-up. Attached Figure Description

[0032] Figure 1 Scanning electron microscope (SEM) images of the modified starch for polyester sizing prepared in Example 1; (a) native starch; (b) modified starch obtained in Example 1; Figure 2 The XRD pattern of the modified starch for polyester sizing prepared in Example 1; Figure 3 The image shows the TGA diagram of the modified starch for polyester sizing prepared in Example 1. Detailed Implementation

[0033] 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.

[0034] The testing method involved in this invention: 1. Test method for elongation at break of slurry film 12 g of dried modified starch, 2.4 g of glycerol, and 188 g of deionized water were placed in a 500 mL flask and heated from room temperature to 95 °C. The mixture was stirred at this temperature for 60 min to form a starch paste. After cooling the starch paste to 60 °C, it was poured into a 400 mm * 400 mm mold and dried at 65 RH and 20 °C to form a starch slurry film for subsequent testing. The tensile testing machine is a mechanical property testing device specifically designed for low-load materials such as films, monofilaments, and microfiber yarns. Its design complies with the 0.5-grade accuracy requirements of GB / T 3923.1-2013. The entire machine is driven by a micro-stepping motor and a precision ball screw, coupled with a high-resolution force sensor and a grating displacement encoder, enabling real-time acquisition of force values ​​of 0.00001 N and displacements of 0.0001 mm. PC software can automatically output the maximum tensile force, elongation at break, elastic modulus, and stress-strain curves. The main technical parameters of the tensile testing machine include a tensile force range of 0-10 N, a testing speed of 0.02 mm / s, data recording every 0.01 s, and a sample width of 1-20 mm. In this invention, a film width of 1 mm is used to test the elongation at break.

[0035] 2. Test methods for sizing rate and desizing rate The yarn was wound around an aluminum frame and weighed after drying (accurate to 0.01 g). A 1 wt% starch paste was prepared by dispersing 3 g of dried starch sample in a 500 mL three-necked flask containing 297 mL of deionized water and stirring. The flask was then placed in a water bath and heated from room temperature to 95 °C, stirring at this temperature for 60 min to form the starch paste sample. The prepared starch paste sample was poured into a 500 mL beaker, and the yarn frame was placed in the beaker and stirred to sizing. The yarn was then air-dried in a cool, dry place and weighed after drying. The test was performed three times, and the average sizing result was calculated.

[0036] The sizing rate is calculated using formula (1):

[0037] In the formula S —Sizing rate of the fabric; G 1—The mass of the fabric after sizing, in grams; G 0 — The mass of the fabric before sizing, in grams.

[0038] Prepare a desizing solution with a liquor ratio of 1:50. The composition of the desizing solution is: 4 mL / L hydrogen peroxide, 2 g / L NaOH, and 2 g / L JFC (as a penetrant). Then, place the flask containing the desizing solution into a 90℃ water bath, and then put the sized yarn into a beaker and boil for 30 min to desizing. After desizing, wash the yarn three times with hot water, dry it in a cool and dry place, and weigh it. Calculate the desizing rate according to formula (2):

[0039] In the formula F —Desizing rate of the fabric; G 0 — Mass of the fabric before sizing, in grams; G 1—The mass of the fabric after sizing, in grams; G 2 — The mass of the fabric after desizing, in grams.

[0040] Example 1 A method for preparing ternary solid-phase esterified composite bio-based modified polyester starch for sizing includes the following steps: (1) Deionized water and phosphorus oxychloride (POCl3) were added to a beaker at a mass ratio of 150:1. Corn starch and deionized water were added at a mass ratio of 2:3. The mixture was then stirred in a water bath at 50 °C for 5 h for acid hydrolysis modification. After adjusting the pH to 7, the mixture was washed with deionized water and anhydrous ethanol three times, filtered, vacuum dried, and ground to obtain acid hydrolyzed starch (CLS) containing phosphoric acid groups. (2) Mix 200 g of the phosphoric acid hydrolyzed starch obtained in step (1) with 200 g of ethanol and add it to a 1 L beaker. Then add 18 g of itaconic acid (IA) and 20 g of citric acid (CA). Stir evenly at room temperature, filter, dry and pulverize to obtain a mixture of modifiers. (3) The modifier mixture was added to a twin-screw extruder. The temperatures of the six reaction chambers of the extruder were 40 ℃, 60 ℃, 80 ℃, 100 ℃, 120 ℃ and 135 ℃, respectively. The feed rate of the extruder was 60 g / min and the screw speed was 120 rpm. After washing with 60 wt% ethanol and acetone three times, filtration, vacuum drying, and grinding, citric acid-itaconic acid synergistic modified corn starch (CIS) was obtained. (4) Mix 100 g of the citric acid-itaconic acid co-modified corn starch (solid-phase esterified starch) obtained in step (3) with 100 g of ethanol in a beaker, add 10 g of phytic acid (PA), and stir at room temperature for 2 h at a speed of 500 rpm. After filtering the starch suspension, heat and solidify it in a 60 ℃ oven for 4 h, and then grind and pulverize it to obtain phytic acid functionalized citric acid-itaconic acid co-modified corn starch (PA / CIS).

[0041] Result characterization 1. Scanning electron microscopy (SEM) results of the modified starch used for sizing polyester prepared in Example 1 are as follows: Figure 1 As shown: like Figure 1 As shown, the original corn starch granules have a smooth surface and uneven size distribution, but retain an intact structure with no obvious porosity or signs of erosion. Starch modified with citric acid, itaconic acid, and phytic acid maintained the basic granule morphology, but significant surface damage and porosity were observed. These morphological observations indicate that chemical modification mainly occurs at active sites on the granule surface, primarily in the amorphous regions of the starch, with minimal reaction occurring within the granules.

[0042] 2. XRD results of the modified starch for polyester sizing prepared in Example 1 are as follows: Figure 2 As shown: The crystal structure of the modified starch remained unchanged, indicating that the modification reaction occurred in the amorphous region of the starch. Simultaneously, the starch crystallinity decreased, suggesting that the modification reaction disrupted the crystalline structure of the starch to some extent. The starch crystal form was broken down, intermolecular hydrogen bonding forces weakened, and the thermoplasticity of the modified starch improved.

[0043] 3. The results of the modified starch TGA for polyester sizing prepared in Example 1 are as follows: Figure 3 As shown: The decrease in the thermal decomposition temperature of modified starch indicates that the reaction of modified starch reduces the crystalline region. As the amount of itaconic acid added increases, the crystallinity decreases, and the intermolecular forces decrease, thus lowering the thermal decomposition temperature.

[0044] 4. The elongation at break of the polyester sizing film prepared with modified starch in Example 1 was 6.93%; after 100 cycles of rubbing the film with 100-grit sandpaper, its abrasion was 0.137 mg / cm. -2 The modified starch achieved a sizing rate of 6.53% and a desizing rate of 92.34% for polyester fabrics.

[0045] Example 2 The only difference from Example 1 is that in step (2), the amount of itaconic acid (IA) used is 10, 12, 14, 16, 18, and 20 g, respectively. All other parameters and conditions are the same as in Example 1. The results of the elongation at break of the modified starch slurry film are shown in Table 1 below; the abrasion of the modified starch slurry film is shown in Table 2 below; and the results of the sizing rate and desizing rate of the modified starch slurry film are shown in Table 3 below.

[0046] Table 1

[0047] Table 2

[0048] Table 3

[0049] Example 3 The only difference from Example 1 is that in step (3), phytic acid is replaced with gallic acid, ellagic acid and tannic acid respectively, while other parameters and conditions are the same as in Example 1.

[0050] Gallic acid: The elongation at break of the pulp film was measured to be 6.12%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, the wear was 0.183 mg·cm. -2 The modified starch achieved a sizing rate of 6.26% and a desizing rate of 90.35% for polyester fabrics.

[0051] Ellagic acid: The measured elongation at break of the pulp film was 5.87%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.192 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 5.81% and a desizing rate of 89.79% for polyester fabrics.

[0052] Tannic acid: The measured elongation at break of the pulp film was 6.36%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.174 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 6.67% and a desizing rate of 91.60% for polyester fabrics.

[0053] Example 4 The only difference from Example 1 is that the temperature of the reaction chamber in step (2) is adjusted to 30 ℃, 50 ℃, 70 ℃, 90 ℃, 110 ℃, and 130 ℃; other parameters and conditions are the same as in Example 1.

[0054] The measured elongation at break of the pulp film was 6.63%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.156 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 5.88% and a desizing rate of 91.15% for polyester fabrics.

[0055] Comparative Example 1 The only difference from Example 1 is that itaconic acid (IA) in step (2) is replaced with an equal mass of itaconic anhydride (ITA), while all other parameters and conditions are the same as in Example 1.

[0056] The measured elongation at break of the pulp film was 5.28%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.228 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 5.34% and a desizing rate of 88.47% for polyester fabrics.

[0057] Comparative Example 2 The only difference from Example 1 is that the phytic acid in step (3) is added to the one-step extrusion in step (2), while the other parameters and conditions are the same as in Example 1.

[0058] The measured elongation at break of the pulp film was 4.93%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.247 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 4.31% and a desizing rate of 87.59% for polyester fabrics.

[0059] Comparative Example 3 The only difference from Example 1 is that the citric acid and itaconic acid in step (2) are first mixed with starch and itaconic acid and then extruded, and then the extrudate is mixed with citric acid and extruded. All other parameters and conditions are the same as in Example 1.

[0060] The measured elongation at break of the pulp film was 5.94%; after 100 cycles of rubbing the pulp film with 100-grit sandpaper, its abrasion was 0.168 mg·cm⁻¹. -2 The modified starch achieved a sizing rate of 5.63% and a desizing rate of 90.36% for polyester fabrics.

[0061] 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 ternary solid-phase esterification composite bio-based modified polyester starch for sizing, characterized in that, Includes the following steps: (1) Mix starch and phosphorus oxychloride in water until uniform, and then modify by acid hydrolysis under water bath conditions to obtain acid hydrolyzed starch containing phosphoryl groups; (2) The phosphoryl group-containing acid hydrolyzed starch obtained in step (1) is mixed with ethanol, itaconic acid and citric acid, dried and pulverized to obtain a mixture of modifiers; (3) The modifier mixture obtained in step (2) is added to a twin-screw extruder for extrusion treatment. The extrudate is washed, filtered, dried and crushed to obtain citric acid-itaconic acid synergistic modified starch. (4) The citric acid-itaconic acid synergistic modified starch obtained in step (3) is mixed with ethanol and phytic acid, stirred at room temperature, filtered, heated and solidified, and pulverized to obtain phytic acid functionalized citric acid-itaconic acid synergistic modified starch; that is, the ternary solid-phase esterification composite bio-based modified polyester starch.

2. The preparation method according to claim 1, characterized in that, In step (1), the starch is corn starch or cassava starch; the mass ratio of starch to phosphorus oxychloride is 100~150:1; the mass ratio of starch to water is 1~5:

3.

3. The preparation method according to claim 1, characterized in that, In step (1), the water bath conditions are: 40~50 ℃, 3~5 h.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of phosphoric acid hydrolyzed starch to ethanol is 10:6 to 10:10; the mass ratio of phosphoric acid hydrolyzed starch to itaconic acid is 100:5 to 10; and the mass ratio of phosphoric acid hydrolyzed starch to citric acid is 100:

10.

5. The preparation method according to claim 1, characterized in that, In step (3), the temperatures of the six reaction chambers of the twin-screw extruder are 20~40℃, 40~60℃, 60~80℃, 80~100℃, 100~120℃, and 120~140℃, respectively; the feed rate of the twin-screw extruder is 20~80 g / min, and the rotation speed is 60~120 rpm.

6. The preparation method according to claim 1, characterized in that, In step (4), the mass ratio of citric acid-itaconic acid synergistic modified starch to ethanol is 10:8~10; the mass ratio of citric acid-itaconic acid synergistic modified starch to phytic acid is 100:

10.

7. The preparation method according to claim 1, characterized in that, In step (4), the stirring time at room temperature is 2 h and the speed is 500 rpm; the heating and curing temperature is 60 ℃ and the time is 4 h.

8. A ternary solid-phase esterified composite bio-based modified polyester starch prepared by the preparation method according to any one of claims 1-7.

9. The application of the ternary solid-phase esterification composite bio-based modified starch for polyester sizing as described in claim 8 in polyester sizing.

10. A method for improving the sizing rate and desizing rate of polyester fabrics, characterized in that, The method described above uses the ternary solid-phase esterification composite bio-based modified polyester starch prepared according to claim 8 for sizing.

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