A sizing paste for pure polylactic acid yarn and a sizing method of pure polylactic acid yarn

Abstract

The application discloses a sizing sizing material for pure polylactic acid yarn and a sizing method of the pure polylactic acid yarn. The sizing formula comprises a main sizing material and an additive in a mass ratio of 60-100:4-10; the main sizing material comprises the following raw materials in parts by weight: polyacrylate 25-50 parts, modified starch 25-50 parts, polyvinyl alcohol 10-20 parts and water 650-750 parts. The sizing material and the sizing process ensure that the sizing material has good adhesion with polylactic acid fibers, the sizing film has good wear resistance, the sizing has good flexibility, the warp breakage of a loom is reduced, and the efficiency of the loom is improved.

Description

Technical Field

[0001] This invention relates to the field of fiber dyeing, and more particularly to a sizing agent and a sizing method for pure polylactic acid yarn. Background Technology

[0002] Polylactic acid (PLA) is a thermoplastic polymer with good solubility and biocompatibility. It has good crystallinity, transparency and heat resistance. The PLA macromolecule has a variety of three-dimensional structures and can be divided into poly-D-lactic acid, poly-L-lactic acid and poly-racemic lactic acid. Generally speaking, poly-L-lactic acid is used to produce PLA fibers. Its molecular structure is isotactic and has strong crystallinity, while the other two types of PLA have structures and properties that are not suitable for spinning.

[0003] Polylactic acid (PLA) fibers can be widely used in clothing fabrics and disposable hygiene products, but PLA fiber fabrics are difficult to produce, especially pure PLA yarns which have poor mechanical properties and are prone to breakage during fabric weaving, adding difficulties to the weaving process.

[0004] Sizing is a crucial step in woven fabric production. A suitable sizing process can improve yarn weaveability, reduce yarn breakage on the weaving machine, increase machine efficiency, and improve fabric quality. Polylactic acid (PLA) fibers contain numerous ester and methyl groups but lack hydrophilic polar and reactive groups, making them hydrophobic fibers. Based on the principle of "like dissolves like," current sizing agents used for PLA sizing mainly contain esterified starch, polyester sizing agents, and polyvinyl alcohol, with esterified starch being used in higher amounts than polyester sizing agents. While these sizing agents have some adhesion to PLA fibers, the high uniformity and tight arrangement of PLA fibers within the yarn result in low adsorption of the sizing agent, leading to weak sizing, a stiffer hand feel, and minimal improvement in strength. Therefore, designing suitable sizing agent formulations and sizing processes for pure PLA fibers to improve weaveability has become a key research focus. Summary of the Invention

[0005] The main objective of this invention is to provide a sizing agent and sizing method for pure polylactic acid yarn, which can effectively improve the weaveability of the yarn.

[0006] To achieve the above objectives, the present invention provides a sizing agent for pure polylactic acid yarn, comprising a main sizing agent and an auxiliary agent in a mass ratio of 60-100:4-10;

[0007] The main slurry, by weight, comprises the following raw materials: 25-50 parts polyacrylate, 25-50 parts modified starch, 10-20 parts polyvinyl alcohol, and 650-750 parts water.

[0008] Furthermore, the raw material composition of the main slurry is specifically as follows: 25 parts modified starch, 10 parts polyvinyl alcohol, 50 parts polyacrylate, and 700 parts water.

[0009] Furthermore, the additive is any one or more of softeners, antistatic agents, smoothers, and penetrants mixed in any proportion.

[0010] Furthermore, the polyacrylate is composed of SFT206, PT, and QL-89 mixed in a mass ratio of 1:1:10.

[0011] Furthermore, the modified starch is composed of esterified starch PRS-T and high-performance starch P24 mixed in a mass ratio of 1:1.

[0012] Furthermore, the polyvinyl alcohol is PVA205.

[0013] This invention also provides a sizing method for pure polylactic acid yarn. The method uses the above-mentioned sizing sizing agent and employs a Tsudakoma HS40 sizing machine for sizing. The sizing parameters are set as follows: warp tension 8 kg / spindle, feed elongation 0-0.1%, sizing tank elongation -0.1-0%, dry split elongation 1.8-2.0%, sizing tank pressure 14-24 KN, single-dip three-pressure method, pre-pressure followed by main pressure, winding tension 2300 N, winding speed 40-60 m / min, sizing tank temperature 85-90℃, sizing tank viscosity 6-7 S, and drying cylinder temperature not exceeding 110℃.

[0014] Furthermore, the yarn specification is polylactic acid 40S.

[0015] The beneficial effects of this invention are reflected in:

[0016] In the sizing process, the selection and formulation of sizing agents are very important. This invention uses esterified starch PRS-T and high-performance starch P24 to replace the single esterified starch PRS-T in the existing technology, which can ensure that the sizing solution has better penetration and adhesion to PLA yarn.

[0017] This invention replaces the existing polyester sizing agent PO5S with a polyacrylate composed of multiple components, resulting in better adhesion and permeability to PLA fibers and improved yarn flexibility.

[0018] Secondly, the sizing process conditions are also very important. Polylactic acid is quite sensitive to heat and moisture. If the drying cylinder temperature is too high, the polylactic acid will melt and harden, affecting the strength and elasticity of the yarn. Therefore, this invention selects a drying cylinder temperature of no more than 110°C. The sizing bath temperature should also not be too low, otherwise it will affect the sizing absorption of the yarn. Therefore, this invention selects a sizing bath temperature of 85-90°C.

[0019] The sizing formula and sizing process of this invention ensure that the sizing agent has good adhesion to polylactic acid fibers, the sizing film has good abrasion resistance, the sizing yarn has good flexibility, reduces warp yarn breakage on the weaving machine, and improves the efficiency of the weaving machine. Detailed Implementation

[0020] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0021] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0022] Among them: wax is NP-530 (purchased from Xida Company); antistatic agent is SFT-310 (purchased from Safet Company); PVA205 (purchased from Kuraray Company, Japan); esterified starch PRS-T (purchased from Safet Company); high-performance starch P24 (purchased from Henkel, Germany); polyester slurry P05S (purchased from Linsen Company); SFT206 (purchased from Hefei Safet Company), PT (purchased from Xida Company), and QL-89 (purchased from Qili Company).

[0023] Yarn and fabric specifications: Polylactic acid 40 count, warp density 511.5 ends / 10cm, weft density 283 ends / 10cm, width 160cm, plain weave.

[0024] Example 1

[0025] Sizing methods for pure polylactic acid yarn

[0026] Slurry formulation: 50 parts polyacrylate, 12.5 parts esterified starch PRS-T, 12.5 parts high-performance starch P24, 10 parts PVA205, 700 parts water, 2 parts antistatic agent, and 2 parts wax; the polyacrylate is a mixture of SFT206, PT, and QL-89 in a mass ratio of 1:1:10.

[0027] Sizing was performed using a Tsudakoma HS40 sizing machine. The sizing parameters were set as follows: warp tension 8 kg / shaft, feed elongation 0.1%, sizing tank elongation 0%, dry split elongation 1.6%, sizing tank pressure 22 KN, single immersion and three presses were used, with pre-press followed by main press, winding tension 2300 N, winding speed 55 m / min, sizing tank temperature 85 ± 1 ℃, sizing tank viscosity 6.5 S, and drying cylinder temperature 105 ℃.

[0028] Example 2

[0029] Sizing methods for pure polylactic acid yarn

[0030] Slurry formulation: 25 parts polyacrylate, 25 parts esterified starch PRS-T, 25 parts high-performance starch P24, 10 parts PVA205, 650 parts water, 2 parts antistatic agent, and 2 parts wax; the polyacrylate is a mixture of SFT206, PT, and QL-89 in a mass ratio of 1:1:10.

[0031] Sizing was performed using a Tsudakoma HS40 sizing machine. The sizing parameters were set as follows: warp tension 8 kg / shaft, feed elongation 0.1%, sizing tank elongation 0%, dry split elongation 1.4%, sizing tank pressure 24 KN, single immersion and three presses were used, with pre-pressing followed by main pressing, winding tension 2300 N, winding speed 55 m / min, sizing tank temperature 90 ± 1 ℃, sizing tank viscosity 6.7 S, and drying cylinder temperature 105 ℃.

[0032] Example 3

[0033] Sizing methods for pure polylactic acid yarn

[0034] Slurry formulation: 50 parts polyacrylate, 12.5 parts esterified starch PRS-T, 12.5 parts high-performance starch P24, 15 parts PVA205, 670 parts water, 2 parts antistatic agent, and 2 parts wax; the polyacrylate is a mixture of SFT206, PT, and QL-89 in a mass ratio of 1:1:10.

[0035] Sizing was performed using a Tsudakoma HS40 sizing machine. The sizing parameters were set as follows: warp tension 8 kg / shaft, feed elongation 0.1%, sizing tank elongation 0%, dry split elongation 1.6%, sizing tank pressure 22 KN, single immersion and three presses were used, with pre-press followed by main press, winding tension 2300 N, winding speed 55 m / min, temperature 85 ± 1 ℃, sizing tank viscosity 7.0 S, and drying cylinder temperature 105 ℃.

[0036] Comparative Example 1

[0037] This comparative example was performed according to the method of Example 1, except that 50 parts of polyacrylate were replaced with an equal amount of polyester slurry P05S.

[0038] Comparative Example 2

[0039] This comparative example was performed according to the method of Example 1, except that 12.5 parts of esterified starch PRS-T and 12.5 parts of high-performance starch P24 were replaced with 25 parts of esterified starch PRS-T.

[0040] Comparative Example 3

[0041] This comparative example was performed according to the method of Example 2, except that 25 parts of polyacrylate were replaced with an equal amount of polyester slurry P05S, and 25 parts of esterified starch PRS-T and 25 parts of high-performance starch P24 were replaced with 50 parts of esterified starch PRS-T.

[0042] Sizing effect test

[0043] The yarns treated with sizing in the above embodiments and comparative examples were used for weaving (weaving machine model JAT710), and the weaving performance is shown in Table 1 below.

[0044] Table 1

[0045] Example 1 0.80 620 90.2 Example 2 1.27 620 86.3 Example 3 1.32 620 85.5 Comparative Example 1 2.45 550 74.8 Comparative Example 2 2.20 550 78.5 Comparative Example 3 1.36 580 82.3

[0046] As shown in Table 1, Examples 1-3 of the present invention all exhibit low yarn breakage rates, high weaving machine speeds, and high weaving machine efficiency, indicating that the sizing agent formulation of the present invention can improve the weavability of polylactic acid 40 yarn. In contrast, the existing sizing agents, as represented in the comparative examples, still show a significant difference in weavability at lower machine speeds.

[0047] The performance of the sizing treated yarns from the above embodiments and comparative examples was tested, and the results are shown in Table 2 below. The original yarn strength was 316.7, and the original yarn breaking elongation was 21.2%.

[0048] Table 2

[0049]

[0050] As can be seen from Table 2, the sizing strength of Examples 1-3 is better than that of the comparative examples. At the same time, by adjusting the sizing tension, the elongation of the polylactic acid yarn is reduced, which is beneficial to the weaving of the fabric.

[0051] The sizing agents in different proportions make the sizing yarn feel stiff, which makes it easy to break on the weaving machine. In addition, the sizing yarn has a lot of hairiness, the sizing film is not wear-resistant, the warp breaks of the weaving machine are high, and ultimately the efficiency of the weaving machine is low.

[0052] The effect of sizing concentration on sizing effect

[0053] Based on Example 1, only the amount of water added was changed to 650 parts, 750 parts, and 800 parts, while everything else remained the same as in Example 1. The test results are shown in Table 3 below.

[0054] Table 3

[0055] 650 4.7 10.87 620 88.7 1.12 750 4.2 8.93 620 86.7 1.06 800 4.0 8.70 620 84.2 1.25 Example 1 4.5 9.84 620 90.2 0.8

[0056] As can be seen from Table 3, based on Example 1, with changes in concentration, the loom efficiency and the number of warp breaks and warp stops at 100,000 wefts decreased slightly, but were still quite considerable.

[0057] Effect of modified starch composition on sizing effect

[0058] Based on Example 1, only the ratio of esterified starch PRS-T and high-performance starch P24 was changed, while everything else remained the same as in Example 1. The test results are shown in Table 4 below.

[0059] Table 4

[0060]

[0061] As can be seen from Table 4, the yarn weavability is best improved when the ratio of PRS-T to P24 is 1:1. However, both increasing and decreasing the amount of P24 will lead to a worse sizing effect.

[0062] During the research process of this invention, the inventors discovered that adding P24 can improve the adhesion to PLA fibers and improve the abrasion resistance of the film. However, if the amount added is too large, it will reduce the permeability to the yarn. After comprehensive comparison, the best effect is achieved when the two are in a 1:1 ratio, which has better permeability and adhesion to the yarn.

[0063] The effect of polyacrylate composition on sizing effect

[0064] Based on Example 1, only the ratio of polyacrylate was changed, while everything else remained the same as in Example 1. The test results are shown in Table 5 below.

[0065] Table 5

[0066]

[0067] As can be seen from Table 5, the yarn weaveability is best improved when the ratio of SFT-206:PT:QL-89 is 1:1:10.

[0068] Polylactic acid (PLA) fiber contains a large number of ester and methyl groups, but lacks hydrophilic polar and reactive groups. QL-89, polymerized from acrylic acid and acrylate monomers, contains a large number of carboxyl and ester groups, sharing a similar ester structure with PLA fiber. This results in strong adhesion to PLA fiber. Furthermore, QL-89's emulsion particles are small, allowing for easy penetration into the yarn, forming a flexible and absorbent sizing film without causing re-adhesion. PT sizing agent contains polar groups such as carboxyl, hydroxyl, ester, and amide groups, providing good adhesion and penetration to PLA fiber. PT also contains surfactants, enhancing the miscibility of starch with other sizing agents. SFT-206, also a multi-component acrylic sizing agent containing carboxyl and ester groups, exhibits excellent adhesion to PLA fiber. The addition of PT and SFT-206 improves the abrasion resistance of the sized yarn. Overall, a 1:1:10 ratio of these three agents yields the best results.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sizing agent for pure polylactic acid yarn, characterized in that, Includes main slurry and additives in a mass ratio of 60–100:4–10; The main slurry, by weight, includes the following raw materials: 25-50 parts of polyacrylate, 25-50 parts of modified starch, 10-20 parts of polyvinyl alcohol, and 650-750 parts of water. The polyacrylate is composed of SFT206, PT and QL-89 in a mass ratio of 1:1:

10. The modified starch is composed of esterified starch PRS-T and high-performance starch P24 mixed in a mass ratio of 1:

1.

2. The sizing agent for pure polylactic acid yarn as described in claim 1, characterized in that, The raw material composition of the main slurry is as follows: 25 parts modified starch, 10 parts polyvinyl alcohol, 50 parts polyacrylate, and 700 parts water.

3. The sizing agent for pure polylactic acid yarn as described in claim 1 or 2, characterized in that, The additive is any one or more of softeners, antistatic agents, smoothers, and penetrants mixed in any proportion.

4. The sizing agent for pure polylactic acid yarn as described in claim 1 or 2, characterized in that, The polyvinyl alcohol is PVA205.

5. A sizing method for pure polylactic acid yarn, characterized in that, Using the sizing agent as described in any one of claims 1 to 4, the sizing method employs a Tsudakoma HS40 sizing machine for sizing. The sizing parameters are set as follows: warp tension 8 kgf / shaft, feed elongation 0–0.1%, sizing tank elongation -0.1–0%, dry split elongation 1.8–2.0%, sizing tank pressure 14–24 kN, single-dip three-pressure method, pre-pressure followed by main pressure, winding tension 2300 N, winding speed 40–60 m / min, sizing tank temperature 85–90 °C, sizing tank viscosity 6–7 S, and drying cylinder temperature not exceeding 110 °C.

6. The sizing method for pure polylactic acid yarn as described in claim 5, characterized in that, The sizing specification is polylactic acid 40S.

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