Preparation and sizing process of desizing-free modified PVA (Polyvinyl Alcohol) slurry

Abstract

The invention relates to the technical field of textile size, in particular to a preparation method of desizing-free modified PVA (polyvinyl alcohol) size and a process for sizing yarns by the aid of the size, and the desizing-free modified PVA size is prepared from raw materials in parts by mass as follows: 40-60 parts of modified PVA, 20-30 parts of oxidized starch, 5-10 parts of polyethylene glycol, 2-5 parts of nanoparticles and 3-8 parts of a compound aid. 100 to 150 parts of deionized water; wherein the modified PVA is prepared by carrying out grafting or copolymerization modification on PVA with the polymerization degree of 1700-1800 and the alcoholysis degree of 88% through an acrylate monomer or one of maleic anhydride and itaconic acid. Compared with the prior art, the method has the advantages that the more hydrophilic modified PVA sizing agent is prepared firstly, then the desizing-free mixed sizing agent is prepared, and the yarns do not need to be desized in subsequent dyeing or after-finishing processing after being sized in the desizing-free mixed sizing agent, so that the textile technological process can be effectively reduced, the energy consumption is reduced, the sewage discharge is reduced, the damage to the yarns and fabrics is reduced, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of textile sizing technology, and more specifically, to a method for preparing a desizing-free modified PVA sizing agent, and a process for sizing yarn using the sizing agent. Background Technology

[0002] In the textile weaving process, sizing is necessary to improve the abrasion resistance, breaking strength, and cohesion of yarns. Currently, the most widely used sizing agents in the industry are starch and polyvinyl alcohol (PVA), but these have significant drawbacks:

[0003] 1. High energy consumption for desizing: Traditional PVA sizing has poor water solubility after film formation. After weaving, it needs to be removed by desizing processes such as hot water boiling, alkali treatment or enzymatic hydrolysis. This not only increases the number of production steps, but also leads to increased energy consumption (the energy consumption of the desizing process accounts for 25%-30% of the total energy consumption of textile pretreatment).

[0004] 2. Desizing wastewater damages the environment: The desizing process generates a large amount of PVA-containing wastewater (COD value can reach 800-1500mg / L). Wastewater treatment is difficult and costly, which does not meet the requirements of current environmental protection policies.

[0005] 3. Existing desizing-free sizing processes have poor performance: While some existing desizing solutions use starch-PVA blends, starch has poor resistance to mold growth, the sizing film is highly hygroscopic, and the preparation cost is high, making large-scale application difficult. Therefore, developing a desizing-free, stable, and cost-effective sizing material and its sizing process is crucial to resolving the conflict between environmental protection and efficiency in the textile industry.

[0006] Therefore, in view of this, we studied and improved the existing structure, and proposed a method for preparing and sizing modified PVA slurry without desizing to solve the above-mentioned problems. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing methods that require desizing of warp yarns after weaving into fabrics, which result in high energy consumption, large wastewater treatment volume, poor environmental performance, and high cost. This invention provides a method for preparing a desizing agent that does not require desizing, and also provides a sizing process adapted to this agent. This allows the agent to be naturally degraded after weaving or removed with slight treatment during the dyeing and finishing process, thereby reducing energy consumption and pollution, and ensuring the weaving performance of the sized yarn.

[0008] To address the aforementioned problems, the present invention proposes the following technical solution: a non-removable modified PVA slurry, prepared from the following raw materials in parts by weight:

[0009] 40-60 parts of modified PVA were used as the main slurry material and modified by acrylate grafting.

[0010] Add 20-30 parts of oxidized starch to improve the adhesion and biodegradability of the slurry; the degree of oxidation is 8%-12%.

[0011] 5-10 parts of polyethylene glycol are used as a plasticizer to improve the flexibility of the slurry film;

[0012] 2-5 parts of nanoparticles, with a particle size of 50-100 nm, enhance the wear resistance of the slurry film.

[0013] The compound additive consists of 3-8 parts, comprising 0.5-2 parts preservative, 1-3 parts antistatic agent, and 1.5-3 parts wetting agent;

[0014] 100-150 parts of deionized water are used as a solvent;

[0015] The modified PVA is prepared by grafting or copolymerizing PVA with a degree of polymerization of 1700-1800 and a degree of alcoholysis of 88% with acrylate monomers or maleic anhydride or itaconic acid.

[0016] Furthermore, the modified PVA is prepared by dissolving PVA in deionized water at 70-80℃, adding butyl acrylate (5%-8% by mass of PVA) and ammonium persulfate (0.3%-0.5% by mass of PVA), and reacting at 85-90℃ for 2-3 hours to obtain a grafted modified PVA solution.

[0017] Furthermore, the degree of oxidation of the oxidized starch is 8%-12%; or, the oxidized starch can be replaced with phosphate starch, acetate starch, or oxidized-crosslinked modified starch with a degree of substitution in the range of 0.05-0.1.

[0018] Furthermore, the nanoparticles are nano-silica with a particle size of 50-100nm; or, the nanoparticles can be replaced with nano-zinc oxide or nano-calcium carbonate with a particle size of 50-200nm, and their addition amount accounts for 2%-6% of the total mass of the slurry.

[0019] Furthermore, the composite additive consists of 0.5-2 parts of preservative, 1-3 parts of antistatic agent and 1.5-3 parts of wetting agent.

[0020] Furthermore, the preparation method of the non-removable modified PVA slurry includes the following steps:

[0021] Step 1: Prepare modified PVA solution;

[0022] Step 2: Disperse the oxidized starch in deionized water at 40-50℃, then add the modified PVA solution prepared in Step 1, and stir and mix at 60-70℃ for 15-20 minutes.

[0023] Step 3: Add polyethylene glycol, nanoparticles and composite additives to the mixture from Step 2, and mature at 75-80℃ for 40-60 minutes, controlling the final slurry viscosity to 200-300 mPa·s;

[0024] Step 4: Cool the matured slurry to 30-40℃, filter it, and you will get the non-removable slurry.

[0025] Furthermore, the sizing process for desizing modified PVA slurry includes the following steps:

[0026] Immerse the yarn in a sizing solution with a concentration of 10%-15% and a temperature of 65-75℃ for 20-40 seconds.

[0027] The impregnated yarn is then squeezed by rollers at a pressure of 0.2-0.4 MPa.

[0028] The extruded yarn is pre-dried at 80-90℃ and then dried and set at 100-110℃.

[0029] Furthermore, prior to the sizing step, a pretreatment step for the yarn is included: washing the yarn with deionized water at 50-60°C and pre-drying it at 70-80°C until the yarn moisture content is 8%-10%.

[0030] Furthermore, the sizing process is applicable to cotton, cotton-polyester blends, or polyester yarns; the dry weight increase of the yarn after sizing is 8%-12%, and the sizing film can be removed by washing the woven fabric with warm water at 40-50℃.

[0031] Due to the adoption of the above technical solution, the beneficial effects of the preparation of the non-removable modified PVA slurry and its sizing process of the present invention are as follows:

[0032] 1. Significant desizing-free characteristics: The composite sizing film formed by the modified PVA and oxidized starch of this invention can be naturally dissolved by washing with warm water (40-50℃) in the dyeing and finishing process after weaving, without the need for additional desizing, reducing the energy consumption of the desizing process by more than 30%, and reducing the COD value of wastewater to 200-300mg / L, which meets the national first-class discharge standard.

[0033] 2. Excellent sizing performance: The grafted structure of modified PVA improves the adhesion to chemical fiber yarns (adhesion strength is 25%-30% higher than that of pure PVA), and the addition of nano silica and polyethylene glycol improves the abrasion resistance of the sizing film by 15%-20% and the elongation at break by 10%-15%, with a sizing loss rate of less than 1% during weaving.

[0034] 3. Strong process adaptability: The sizing process parameters can be flexibly adjusted according to the type of yarn, and it is suitable for various yarns such as cotton, polyester-cotton, and polyester. The breaking strength of sized yarn is increased by 20%-25%, the hairiness reduction rate reaches 40%-50%, and the weaving efficiency is increased by 10%-15%.

[0035] 4. Controllable cost: The raw materials are all industrial-grade conventional materials. The modified PVA preparation process does not require special equipment. The overall slurry cost is 15%-20% lower than that of imported non-removable slurry, and it is easy to scale up production. Attached Figure Description

[0036] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0037] Figure 1 This is a flowchart illustrating the preparation and sizing process of a non-removable modified PVA slurry according to the present invention.

[0038] Figure 2 This is a spectral diagram of the preparation and sizing process of a non-removable modified PVA slurry according to the present invention. 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 some embodiments of the present invention, and not all 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.

[0040] Example 1: No-de-sizing sizing agent and sizing process for cotton-polyester blended yarn (65 / 35, 40s)

[0041] 1. Slurry raw materials (parts by weight)

[0042] Modified PVA (7% butyl acrylate grafting): 50 parts; Oxidized starch (10% oxidation): 25 parts; PEG-400: 8 parts; Nano silica (80nm particle size): 3 parts; Composite additives (0.8 parts preservative, 1.5 parts antistatic agent, 2 parts wetting agent): 4.3 parts; Deionized water: 120 parts.

[0043] 2. Preparation steps

[0044] Prepared according to steps 1-4 of the above technical solution, wherein the modified PVA reaction temperature is 88℃ and the time is 2.5h, the mixed slurry maturation temperature is 78℃ and the time is 50min, and the finished product viscosity is 250mPa·s (25℃).

[0045] 3. Sizing process parameters

[0046] The sizing concentration was 13%, the sizing temperature was 70℃, the soaking time was 30s, the roller pressure was 0.3MPa, the low temperature drying was 85℃, the high temperature drying was 105℃, and the total drying time was 4min.

[0047] 4. Performance test results

[0048] The sizing process increased the dry weight of the yarn by 10%, improved the breaking strength by 23%, and reduced the hairiness by 45%. After weaving, the yarn was washed with 50°C warm water, resulting in a sizing film dissolution rate of 98%, a wastewater COD value of 250 mg / L, and a weaving sizing loss rate of 0.8%.

[0049] Example 2: No-degrading sizing agent and sizing process for pure polyester yarn (150D)

[0050] 1. Slurry raw materials (parts by weight)

[0051] Modified PVA (8% butyl acrylate grafting): 60 parts; Oxidized starch (12% oxidation): 20 parts; PEG-400: 10 parts; Nano silica (100nm particle size): 5 parts; Composite additives (1 part preservative, 2 parts antistatic agent, 2.5 parts wetting agent): 5.5 parts; Deionized water: 150 parts.

[0052] 2. Preparation steps

[0053] The modified PVA reaction temperature was 90℃ and the time was 3h. The slurry was matured at 80℃ for 60min. The viscosity of the finished product was 300mPa·s (25℃).

[0054] 3. Sizing process parameters

[0055] The sizing concentration was 15%, the sizing temperature was 75℃, the soaking time was 40s, the roller pressure was 0.4MPa, the low temperature drying was 90℃, the high temperature drying was 110℃, and the total drying time was 5min.

[0056] 4. Performance test results

[0057] The sizing process increased the dry weight of the yarn by 12%, improved the breaking strength by 25%, and reduced the hairiness by 48%. After weaving, the yarn was washed with warm water at 45℃, resulting in a sizing film dissolution rate of 99%, a wastewater COD value of 220mg / L, and a weaving sizing loss rate of 0.6%.

[0058] Example 3: High-count, high-density cotton fabric yarn (100 count cotton, warp density 1200 threads / 10cm)

[0059] High-count yarns are fine and have low strength. Traditional sizing agents can easily lead to excessively thick or broken sizing films, affecting weaving efficiency. In addition, high-density fabrics have extremely high requirements for yarn hair control (hair ≤ 2 strands / 10m).

[0060] 1. Slurry raw materials (parts by weight)

[0061] Modified PVA (8% butyl acrylate grafting): 60 parts; Oxidized starch (12% oxidation): 20 parts; PEG-400: 5 parts; Nano silica (100nm particle size): 5 parts; Composite additives (1 part preservative, 2 parts antistatic agent, 2.5 parts wetting agent): 5.5 parts; Deionized water: 150 parts.

[0062] 2. Preparation steps

[0063] The modified PVA reaction temperature was 90℃ and the time was 3h. The slurry was matured at 80℃ for 60min. The viscosity of the finished product was 300mPa·s (25℃).

[0064] 3. Sizing process parameters

[0065] The sizing concentration is 15%, the sizing temperature is 75℃, the soaking time is 45s (to ensure sufficient sizing absorption), the roller pressure is 0.35MPa (to control the dry weight increase rate to 12%), the drying temperature is 85℃ in the low temperature section and 110℃ in the high temperature section (for rapid setting and to reduce yarn stretching), and the total drying time is 5min.

[0066] 4. Performance test results

[0067] The sizing process increased the dry weight of the yarn by 12%, improved the breaking strength by 28%, and reduced the hairiness by 52%. After weaving, washing with 45℃ warm water resulted in a 99% sizing film dissolution rate, a wastewater COD value of 220mg / L, and a weaving sizing loss rate of 0.6%. The weaving breakage rate decreased from 3.5 times / shift to 0.8 times / shift. After dyeing, the fabric required no desizing, and the fabric smoothness improved by 15%.

[0068] Example 4: Elastic synthetic fiber yarn (spandex core-spun yarn, 40D spandex + 75D polyester)

[0069] Elastic yarns are easily stretched and deformed, and traditional sizing processes can easily lead to cracking of the sizing film; in addition, spandex has poor temperature resistance (it is prone to aging when the conventional drying temperature is >110℃).

[0070] 1. Slurry raw materials (parts by weight)

[0071] Modified PVA (8% butyl acrylate grafting): 40 parts; Oxidized starch (12% oxidation): 30 parts; PEG-400: 5 parts; Nano silica (100nm particle size): 5 parts; Composite additives (1 part preservative, 3 parts antistatic agent, 2.5 parts wetting agent): 5.5 parts; Deionized water: 150 parts.

[0072] 2. Preparation steps

[0073] The modified PVA reaction temperature was 90℃ and the time was 3h. The slurry was matured at 80℃ for 60min. The viscosity of the finished product was 300mPa·s (25℃).

[0074] 3. Sizing process parameters

[0075] The sizing concentration is 10%, the sizing temperature is 75℃, the soaking time is 20s (to avoid over-sizing), the roller pressure is 0.2MPa (to reduce stretching), the drying temperature is 80℃ in the low-temperature section and 100℃ in the high-temperature section (to control the spandex aging rate to <5%), the cooling is done with 35℃ cold air (for rapid setting), and the total drying time is 5min.

[0076] 4. Performance test results

[0077] The dry weight of sized yarn increased by 12%, the yarn elastic recovery rate remained at 92% (compared to 95% for unsized yarn), the breaking strength increased by 28%, and the hairiness was reduced by 52%. After weaving, washing with 45℃ warm water resulted in a 99% sizing film dissolution rate, a wastewater COD value of 220mg / L, and a weaving sizing loss rate of 0.7%. No desizing is required after dyeing, fabric smoothness is improved by 15%, and fabric elasticity loss is <3%.

[0078] The following are examples of comparisons:

[0079] I. Comparative Experiment and Effect Verification

[0080] To further verify the superiority of the desizing agent and sizing process of this invention, a comparative experiment was conducted using traditional pure PVA sizing agent (control group 1), commercially available starch + PVA blended sizing agent (control group 2), and the sizing agent of this invention (experimental group) under the same sizing equipment and the same yarn (cotton-polyester blended yarn 65 / 35, 40s). The test indicators and results are as follows:

[0081] (I) Comparison of basic properties of slurry

[0082]

[0083]

[0084] (II) Comparison of yarn properties after sizing

[0085] (III) Environmental Protection vs. Cost Comparison

[0086]

[0087]

[0088] Conclusion: The experimental group of this invention is significantly better than the control group in terms of sizing performance, yarn quality, environmental friendliness and cost control, which verifies the practicality and advanced nature of the desizing-free technology.

[0089] The present invention and its embodiments have been described above. This description is not restrictive. In short, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A non-removable modified PVA slurry, characterized in that, It is prepared from the following raw materials in parts by weight: 40-60 parts of modified PVA 20-30 parts of oxidized starch 5-10 parts of polyethylene glycol, 2-5 parts of nanoparticles 3-8 parts of compound additives, 100-150 parts deionized water; The modified PVA is prepared by grafting or copolymerizing PVA with a degree of polymerization of 1700-1800 and a degree of alcoholysis of 88% with acrylate monomers or maleic anhydride or itaconic acid.

2. The non-removable modified PVA slurry according to claim 1, characterized in that: The modified PVA is prepared by dissolving PVA in deionized water at 70-80℃, adding 5%-8% butyl acrylate and 0.3%-0.5% ammonium persulfate by mass of PVA, and reacting at 85-90℃ for 2-3 hours to obtain a grafted modified PVA solution.

3. The non-removable modified PVA slurry according to claim 1, characterized in that: The oxidation degree of the oxidized starch is 8%-12%; or, the oxidized starch may be replaced with phosphate starch, acetate starch, or oxidized-crosslinked modified starch with a substitution degree in the range of 0.05-0.

1.

4. The non-removable modified PVA slurry according to claim 1, characterized in that: The nanoparticles are nano-silica with a particle size of 50-100nm; or, the nanoparticles can be replaced with nano-zinc oxide or nano-calcium carbonate with a particle size of 50-200nm, and the amount added accounts for 2%-6% of the total mass of the slurry.

5. The non-removable modified PVA slurry according to claim 1, characterized in that: The composite additive consists of 0.5-2 parts of preservative, 1-3 parts of antistatic agent and 1.5-3 parts of wetting agent.

6. The method for preparing a non-removable modified PVA slurry according to claim 1, comprising the following steps: Step 1: Prepare modified PVA solution; Step 2: Disperse the oxidized starch in deionized water at 40-50℃, then add the modified PVA solution prepared in Step 1, and stir and mix at 60-70℃ for 15-20 minutes. Step 3: Add polyethylene glycol, nanoparticles and composite additives to the mixture from Step 2, and mature at 75-80℃ for 40-60 minutes, controlling the final slurry viscosity to 200-300 mPa·s; Step 4: Cool the matured slurry to 30-40℃, filter it, and you will get the non-removable slurry.

7. The sizing process for a non-removable modified PVA slurry according to claim 1 includes the following steps: Immerse the yarn in a sizing solution with a concentration of 10%-15% and a temperature of 65-75℃ for 20-40 seconds. The impregnated yarn is then squeezed by rollers at a pressure of 0.2-0.4 MPa. The extruded yarn is pre-dried at 80-90℃ and then dried and set at 100-110℃.

8. The sizing process for a non-removable modified PVA slurry according to claim 1, characterized in that: Before the sizing step, a yarn pretreatment step is also included: the yarn is washed with deionized water at 50-60℃ and pre-dried at 70-80℃ until the yarn moisture content is 8%-10%.

9. The sizing process for a non-removable modified PVA slurry according to claim 1, characterized in that: The sizing process is suitable for cotton, cotton-polyester blends, or polyester yarns. After sizing, the dry weight of the yarn increases by 8%-12%, and the sizing film can be removed by washing the woven fabric with warm water at 40-50℃.

Images