A method for preparing a biodegradable polyester lint-free wipe

Abstract

The present application relates to the technical field of textile materials, in particular to a preparation method of a biodegradable polyester dust-free cloth. The present application overcomes the problem that the interlayer bonding strength and air permeability of the existing polyester dust-free cloth cannot be considered simultaneously. The present application adopts modified nanocellulose and polylactic acid as the spun-bonding layer, modified starch, polylactic acid and polybutylene succinate as the melt-blown layer, and constructs an SMS sandwich structure; after hot pressing and pre-combination, the polyester dust-free cloth is obtained by water jet reinforcement, biological enzyme activation and cross-linking finishing in sequence. The present application uses water jet physical entanglement to replace traditional gluing, and combines surface chemical cross-linking technology, so as to significantly enhance the interlayer bonding force under the premise of not blocking the fiber micropore, and the obtained dust-free cloth has excellent mechanical properties, air permeability and biodegradation characteristics.

Description

Technical Field

[0001] This invention relates to the field of textile materials technology, specifically to a method for preparing a biodegradable polyester cleanroom cloth. Background Technology

[0002] With the increasing demand for cleanroom wiping materials in high-end manufacturing, single-structure nonwoven materials can no longer simultaneously meet the comprehensive requirements of high strength, high liquid absorption, and low dust generation. Therefore, the use of multi-layer composite technology to prepare layered cleanroom wipes with functional gradients has become the mainstream direction of industry development. Existing layered wiping materials typically adopt a sandwich structure of "spunbond-meltblown-spunbond" or "spunbond-wood pulp". In this layered system, the surface layer is usually composed of continuous filaments, mainly responsible for wear resistance and mechanical support; the core layer is composed of ultrafine fibers or porous materials, mainly responsible for liquid absorption and storage. Currently, in order to respond to environmental protection requirements, using biomass conversion materials such as polylactic acid and polybutylene terephthalate (PET) to replace traditional polypropylene or polyester to prepare fully biodegradable layered cleanroom wipes is a key path to achieving green manufacturing.

[0003] Although layered structure design theoretically combines the advantages of each layer, existing layered composite technologies still face the following bottlenecks in the actual preparation of biodegradable polyester cleanroom wipes: To prevent interlayer delamination and improve overall strength, current technologies often employ large-area hot-rolling bonding or chemical adhesives for interlayer fixation when constructing biodegradable layered materials. While this improves mechanical properties, it severely clogs the micropores between fibers, resulting in poor air permeability and making it difficult for liquids to penetrate the surface layer into the core layer, significantly reducing wiping efficiency. Conversely, reducing bonding points to maintain air permeability can easily lead to surface fibers loosening and detaching during wiping due to the slow crystallization rate and poor adhesion of bio-based materials. Therefore, existing layered polyester cleanroom wipe products still suffer from the inability to simultaneously achieve interlayer bonding strength and air permeability, severely impacting the overall performance of the product.

[0004] Therefore, a method for preparing biodegradable polyester cleanroom cloth is proposed. Summary of the Invention

[0005] The purpose of this invention is to design a method for preparing a biodegradable polyester cleanroom cloth. This invention uses modified nanocellulose and polylactic acid as the spunbond layer, and modified starch, polylactic acid, and polybutylene succinate as the meltblown layer to construct an SMS sandwich structure. After hot-pressing pre-composite, the polyester cleanroom cloth is obtained by sequentially undergoing hydroentanglement reinforcement, bio-enzyme activation, and cross-linking finishing. This invention utilizes hydroentanglement physical entanglement to replace traditional adhesive bonding, combined with surface chemical cross-linking technology, to significantly enhance interlayer bonding without clogging fiber micropores. The resulting cleanroom cloth possesses excellent mechanical properties, air permeability, and biodegradability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Unless otherwise specified, all the following parts are by weight.

[0007] This invention provides a method for preparing a biodegradable polyester cleanroom cloth, comprising the following steps: Masterbatch A was prepared using polylactic acid (PLA) chips and modified nanocellulose, while masterbatch B was prepared using polybutylene succinate (PBS) chips, PLA chips, and modified starch. PLA chips were mixed with masterbatch A and spunbond to form upper and lower spunbond layers. PBS chips, PLA chips, and masterbatch B were mixed and meltblown to form a meltblown layer. The meltblown layer was placed between the upper and lower spunbond layers and pre-composite by hot pressing to obtain a multilayer material. The multilayer material was then subjected to hydroentanglement reinforcement, enzyme activation, and crosslinking finishing liquid impregnation treatment, followed by drying and baking to obtain a polyester cleanroom fabric. Modified nanocellulose is obtained by modifying nanocellulose crystals with epoxidized soybean oil; modified starch is obtained by modifying starch with glutaraldehyde and maleic anhydride.

[0008] Preferably, the preparation method of masterbatch A is as follows: 85 parts of dried polylactic acid chips (melt flow rate: 25±5g / 10min, melting point: 175℃-180℃) are mixed evenly with 15 parts of modified nanocellulose and fed into a twin-screw extruder. The four temperature zones of the extruder are set to 170℃, 185℃, 195℃ and 190℃ respectively, and the screw speed is set to 300rpm. After melt blending and extrusion granulation, masterbatch A is obtained.

[0009] Preferably, the preparation method of modified nanocellulose is as follows: 90-110 parts of nanocellulose crystals (diameter: 10-20nm, length: 200-400nm) are dispersed in 500 parts of anhydrous ethanol. After ultrasonic dispersion at 800W power for 30min, 190-210 parts of epoxidized soybean oil (epoxide value ≥6.0%, viscosity at 25℃: 300-400cP) and 2 parts of p-toluenesulfonic acid are added to obtain a mixed solution. The mixed solution is heated to 75℃ and refluxed at a stirring speed of 500rpm for 5-7h. After the reaction is completed, the product is separated by centrifugation and washed 3 times with acetone. Finally, it is dried to constant weight under vacuum at 60℃ to obtain modified nanocellulose.

[0010] Preferably, the preparation method of masterbatch B is as follows: 70 parts of polybutylene succinate chips (melt flow rate: 20±5g / 10min, melting point: 110℃-115℃), 10 parts of polylactic acid chips and 20 parts of modified starch are mixed, and the temperature zones of the twin-screw extruder are set to 115℃, 125℃, 130℃ and 125℃, and masterbatch B is obtained by extrusion granulation.

[0011] Preferably, the modified starch is prepared as follows: 95-105 parts of starch (amylose content ≥20%, number average molecular weight: 3000-5000 Da) are dissolved in 400 parts of acidic aqueous solution with pH 3.0, heated to 40°C, and 13-17 parts of glutaraldehyde are slowly added dropwise. The reaction is carried out at a constant temperature for 2 hours, then cooled to 25°C, and the pH is adjusted to alkaline with alkali solution to obtain a reaction solution. 10 parts of maleic anhydride are dissolved in 15 parts of anhydrous acetone to obtain a maleic anhydride solution, which is slowly added dropwise to the reaction solution, and the reaction is continued for 3 hours for end-capping. Finally, the pH is adjusted to neutral, and the modified starch is obtained by spray drying (inlet air temperature 160°C, outlet air temperature 80°C).

[0012] Preferably, the preparation method of the spunbond layer is as follows: 95-105 parts of polylactic acid chips and 3-7 parts of masterbatch A are mixed evenly as raw materials and fed to the upper and lower spunbond spinning positions respectively. The screw extrusion temperature is set to 210-220℃, the spinning box temperature is set to 220℃, and after the melt is sprayed out by the component, it is solidified under side-blowing cooling at a temperature of 20℃ and a wind speed of 0.6m / s, and then drawn by a high-speed airflow of 4500m / min to form monofilaments with a fineness of 2.2dtex and a single layer basis weight of 30g / m² on the forming screen. 2 spunbond layer.

[0013] Preferably, the meltblown layer is prepared as follows: 75-85 parts of polybutylene succinate chips, 20 parts of polylactic acid chips, and 8-12 parts of masterbatch B are mixed evenly and fed to a meltblown die located between two spunbond sites. The screw extrusion temperature is set to 220-240℃, the hot air temperature to 260℃, the hot air pressure to 0.3MPa, and the receiving distance to 150mm. The melt is drawn into fibers with an average diameter of 2-5μm and directly sprayed onto the lower spunbond layer to form a basis weight of 60g / m². 2 The meltblown layer.

[0014] Preferably, the preparation method of the multilayer material is as follows: the upper spunbond layer is covered on the meltblown layer to form an SMS sandwich structure, and the three layers of material are pre-pressed by a pair of hot rolling rolls with a temperature of 75-85℃ and a linear pressure of 15-25kg / cm to obtain the multilayer material.

[0015] Preferably, the specific process of hydroentangling reinforcement, enzyme activation, and cross-linking finishing solution padding is as follows: Multilayer materials are reinforced using a hydroentangling machine, employing a three-stage hydroentangling process ("forward-backward-forward") with water pressures set sequentially to 40 bar, 80 bar, and 100 bar to obtain reinforced multilayer materials; the reinforced multilayer materials are then introduced into a working tank containing keratinase (enzyme activity 100,000 U / G, pH: 8.0-8.5) (controlling the bath ratio to 1:20-1:30) and immersed at 55°C for 15-25 minutes to obtain activated multilayer materials; subsequently… The activated multilayer material is subjected to a crosslinking finishing solution through a two-dip and two-roll process (70% roll-off). After dipping and rolling, the activated multilayer material is first pre-dried at 80℃ for 1-5 minutes, and then enters the setting machine for baking at 105-115℃ for 2 minutes. Finally, it is wound and slit to obtain polyester cleanroom fabric. The crosslinking finishing solution contains 2% itaconic acid (CAS No.: 97-65-4), 0.1% ammonium persulfate (CAS No.: 7727-54-0), and 0.5% polyether modified silicone oil (CAS No.: 67674-67-3), with the balance being deionized water.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Nanocellulose, acting as a rigid nucleating agent, improves the crystallinity and modulus of polylactic acid (PLA), imparting excellent mechanical properties. Meanwhile, the grafted epoxidized soybean oil long chains act as a toughening agent, effectively repairing interfacial defects between PLA and the matrix, thus enhancing the fiber's mechanical strength. This modification significantly improves the PLA fiber's brittleness and tendency to shed fibers, making the cleanroom cloth less prone to damage when wiping rough surfaces, meeting the requirements for use in high-cleanliness environments.

[0017] 2. The large number of hydrophilic groups in modified starch, combined with the capillary effect of meltblown microfiber, makes the core layer a highly efficient "liquid-absorbing sponge," greatly enhancing its ability to grasp solvents and oil stains. At the same time, the acetal / ketal bonds in modified starch will preferentially break in acidic soil environments, inducing the formation of pores and disintegration inside the material. Combined with the degradation characteristics of polybutylene succinate, the overall degradation cycle is shortened, realizing the biodegradation of polyester cleanroom cloth.

[0018] 3. Traditional layered materials often use hot rolling or adhesive bonding for fixation, which easily clogs pores. This invention first uses a high-pressure hydroentangling process to forcefully insert the filaments of the upper and lower spunbond layers into the middle meltblown layer, forming a physical rivet structure in the Z-direction to prevent delamination. Subsequently, through enzyme activation and surface chemical cross-linking with itaconic acid, molecular-level micro-welding points are formed at the fiber contact points. This non-adhesive bonding method ensures longitudinal strength while preserving the original micro-nano porous structure of the meltblown layer, thus achieving a balance between high strength and high air permeability.

[0019] 4. Keratin pretreatment directionally etches active sites (hydroxyl / carboxyl groups) on the fiber surface, providing anchor points for subsequent itaconic acid grafting; subsequent heat baking initiates the formation of an extremely thin cross-linked network film of itaconic acid on the fiber surface. This film not only seals microcracks on the fiber surface and prevents dust from falling off, but its rich carboxyl groups also significantly reduce the water contact angle, solving the problem of wiping residue caused by the hydrophobicity of polyester materials.

[0020] 5. A core-sheath structure is adopted in the spunbond layer, concentrating the modified nanocellulose masterbatch in the sheath layer or as a whole, which saves costs and maximizes the surface modification effect of the nano-reinforcing phase. Meanwhile, considering the poor thermal stability of starch, a low-temperature gradient extrusion process is used to prepare masterbatch B, avoiding carbonization and degradation of starch during processing, ensuring the continuity and uniformity of the meltblown fiber layer, and guaranteeing the consistent quality of the final product. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the polyester cleanroom cloth in this invention.

[0022] In the diagram: 1. Spunbond layer; 2. Meltblown layer. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0024] For details, please refer to [link / reference]. Figure 1 This invention provides a method for preparing a biodegradable polyester cleanroom cloth, the technical solution of which is as follows: Example 1 100 parts of nanocellulose crystals were dispersed in 500 parts of anhydrous ethanol and ultrasonically dispersed at 800W for 30 min. Then, 200 parts of epoxidized soybean oil and 2 parts of p-toluenesulfonic acid were added to obtain a mixed solution. The mixed solution was heated to 75℃ and refluxed at 500rpm for 6 h. After the reaction was completed, the product was separated by centrifugation and washed three times with acetone. Finally, it was dried to constant weight under vacuum at 60℃ to obtain modified nanocellulose. 100 parts of starch were dissolved in 400 parts of acidic aqueous solution with a pH of 3.0, heated to 40°C, and 15 parts of glutaraldehyde were slowly added dropwise. The reaction was carried out at a constant temperature for 2 hours, then cooled to 25°C, and the pH was adjusted to alkaline with alkali solution to obtain the reaction solution. 10 parts of maleic anhydride were dissolved in 15 parts of anhydrous acetone to obtain a maleic anhydride solution, which was slowly added dropwise to the reaction solution, and the reaction was continued for 3 hours for end-capping. Finally, the pH was adjusted to neutral, and the modified starch was obtained by spray drying.

[0025] 85 parts of dried polylactic acid chips were mixed evenly with 15 parts of modified nanocellulose and fed into a twin-screw extruder. The four temperature zones of the extruder were set to 170℃, 185℃, 195℃ and 190℃ respectively, and the screw speed was set to 300 rpm. After melt blending and extrusion granulation, masterbatch A was obtained. 70 parts of polybutylene succinate chips, 10 parts of polylactic acid chips and 20 parts of modified starch were mixed, and the temperature zones of the twin-screw extruder were set to 115℃, 125℃, 130℃ and 125℃. Masterbatch B was obtained by extrusion granulation. 100 parts of polylactic acid chips and 5 parts of masterbatch A were mixed evenly as raw materials and fed to the upper and lower spunbond spinning positions respectively. The screw extrusion temperature was set to 215℃ and the spinning box temperature to 220℃. After the melt was sprayed out by the assembly, it was solidified under side-blowing cooling at a temperature of 20℃ and a wind speed of 0.6m / s, and then drawn by a high-speed airflow of 4500m / min to form monofilaments with a fineness of 2.2dtex and a single layer basis weight of 30g / m² on the forming screen. 2 spunbond layer; 80 parts of polybutylene succinate chips, 20 parts of polylactic acid chips, and 10 parts of masterbatch B were mixed evenly and fed into a meltblown die located between two spunbond sites. The screw extrusion temperature was set to 230℃, the hot air temperature to 260℃, the hot air pressure to 0.3MPa, and the receiving distance to 150mm. The melt was drawn into fibers with a diameter of 2-5μm and directly sprayed onto the lower spunbond layer to form a fiber with a basis weight of 60g / m². 2 The meltblown layer; The upper spunbond layer is covered on the meltblown layer to form an SMS sandwich structure. The three layers of materials are pre-pressed by a pair of hot rolling rolls with a temperature of 80℃ and a linear pressure of 20kg / cm to obtain a multi-layer material. Multilayer materials are reinforced using a hydroentangling machine with a three-stage hydroentangling process of "positive-negative-positive" and water pressure set sequentially to 40 bar, 80 bar, and 100 bar to obtain reinforced multilayer materials. The reinforced multilayer materials are then introduced into a working tank containing keratinase and immersed at 55°C for 20 minutes to obtain activated multilayer materials. Subsequently, the activated multilayer materials are subjected to a crosslinking finishing solution through a two-dip and two-ply process (70% roll-off rate). The activated multilayer materials after immersion and plying are first pre-dried at 80°C for 3 minutes and then placed in a setting machine for baking at 110°C for 2 minutes. Finally, they are wound and slit to obtain polyester cleanroom fabric.

[0026] Examples 2-5 refer to the parameter conditions in Example 1, with specific differences shown in Table 1.

[0027] Table 1 Parameters and conditions for Examples 1-5 Example Example 1 Example 2 Example 3 Example 4 Example 5 Dosage / parts of nanocellulose crystals 100 90 95 105 110 Dosage / part of epoxidized soybean oil 200 190 195 105 210 Reflux reaction time / h 6 5 5.5 6.5 7 Starch dosage / serving 100 95 98 103 105 Dosage / part of glutaraldehyde 15 13 14 16 17 Amount / serving of polylactic acid chips 100 95 97 103 105 Dosage of Masterbatch A (per serving) 5 3 4 6 7 Temperature of spunbond screw extrusion / ℃ 215 210 220 210 220 Amount / part of polybutylene succinate slices 80 75 78 82 85 Dosage of Masterbatch B (per serving) 10 8 9 11 12 Temperature of meltblown layer screw extrusion / ℃ 230 220 225 235 240 Temperature of hot rolling rolls / °C 80 75 85 85 75 Linear pressure / kg / cm 20 15 18 22 25 Impregnation treatment time / min 20 15 25 15 25 Pre-baking time / min 3 1 2 4 5 Temperature for shaping and baking / ℃ 110 105 105 115 115 ; Comparative Example 1 follows the same parameters and conditions as in Example 1, except that the nanocellulose is not modified.

[0028] Comparative Example 2 follows the same parameters and conditions as in Example 1, except that no modified nanocellulose is added.

[0029] Comparative Example 3 follows the same parameters and conditions as in Example 1, except that the starch is not modified.

[0030] Comparative Example 4 follows the same parameters and conditions as in Example 1, except that modified starch is not added.

[0031] Comparative Example 5 follows the same parameters and conditions as in Example 1, except that the upper and lower spunbond layers are directly laminated, and the meltblown layer is removed.

[0032] Comparative Example 6 uses the same parameters and conditions as in Example 1, except that the upper and lower spunbond layers are removed, and the same weight is achieved only by increasing the thickness of the meltblown layer.

[0033] Comparative Example 7 uses the same parameters and conditions as in Example 1, except that it uses traditional adhesive to fix the layered material, and copolyester hot melt adhesive is sprayed between the layers and hot-pressed to bond them together.

[0034] Comparative Example 8 follows the same parameters and conditions as in Example 1, except that hydroentanglement reinforcement is not performed.

[0035] Comparative Example 9 follows the same parameters and conditions as in Example 1, except that enzyme activation treatment is not performed.

[0036] Comparative Example 10 follows the same parameters and conditions as in Example 1, except that no crosslinking finishing liquid padding treatment is performed.

[0037] Comparative Example 11 follows the same parameters and conditions as in Example 1, except that the crosslinking finishing solution does not contain itaconic acid and ammonium persulfate.

[0038] Experimental Example 1: Tensile Strength, Hydrophilicity and Degradation Rate Test The tensile strength of Examples 1-5 and Comparative Examples 1-4 was tested according to GB / T 12914 standard; the hydrophilicity of Examples 1-5 and Comparative Examples 1-4 was tested according to AATCC 79-2010 standard (the absorption time of a certain amount of water was recorded with a stopwatch; the shorter the time, the better the wettability of the sample); the degradation rate (change in sample mass before and after) in the soil burial degradation experiment of Examples 1-5 and Comparative Examples 1-4 was tested after 90 days; the results are shown in Table 2.

[0039] Table 2 Tensile strength, hydrophilicity, and degradation rate of Examples 1-5 and Comparative Examples 1-4 Example Longitudinal tensile strength / N / cm Transverse tensile strength / N / cm hydrophilicity / min Degradation rate / % Example 1 74.83 38.71 1.91 64.52 Example 2 73.97 37.92 2.05 63.88 Example 3 74.25 38.19 2.02 64.15 Example 4 74.58 38.37 1.98 64.36 Example 5 74.73 38.56 1.95 64.61 Comparative Example 1 61.24 31.54 1.96 62.15 Comparative Example 2 56.81 29.12 2.01 61.80 Comparative Example 3 63.45 32.83 5.32 48.52 Comparative Example 4 68.92 35.20 10.87 21.26 ; Table 1 shows that the longitudinal tensile strength of Comparative Example 1 is lower than that of Example 1. This is because the surface of the unmodified soybean oil-based nanocellulose contains a large number of hydrophilic hydroxyl groups, which have extremely poor compatibility with the hydrophobic polylactic acid matrix. This leads to severe agglomeration of the nanocellulose during spinning. These agglomerates not only fail to provide skeletal reinforcement but also become stress concentration points within the fiber, making the cleanroom fabric more prone to breakage under stress. However, since the modified starch is still retained in the system, its hydrophilicity and degradation rate are not significantly different from those of Example 1, indicating that the modification of nanocellulose mainly affects the mechanical properties of the material. The tensile strength of Comparative Example 2 is the lowest among all groups, which fully demonstrates that nanocellulose plays a crucial reinforcing role in this invention. Without the high modulus support of nanocellulose, pure polylactic acid fibers cannot provide sufficient rigidity in the spunbond layer, resulting in a significant decline in the mechanical properties of the finished product. Comparative Example 3 exhibited significant disadvantages in both hydrophilicity and degradation rate. This is because the unmodified starch, lacking glutaraldehyde and maleic anhydride, lacked chemical bonding with the matrix, resulting in extremely uneven dispersion during meltblowing and an inability to form effective liquid absorption channels. More importantly, the absence of acid-sensitive bonds (acetal bonds) prevented the starch from rapidly breaking down and disintegrating in response to environmental acidity during the initial stages of degradation. Consequently, the overall biodegradation process lacked an induction triggering mechanism, leading to a significantly slower degradation rate compared to Example 1. Furthermore, poor compatibility resulted in weak interfacial bonding, causing its mechanical strength to be lower than that of Example 1. Comparative Example 4 showed extreme polarization. Although its tensile strength was superior to Comparative Examples 2 and 3, its hydrophilicity was extremely poor, essentially hydrophobic, and its 90-day degradation rate was only 21.26%. This indicates that without the introduction of starch-based degradation aids, although the matrix possesses a certain mechanical strength, it completely loses the rapid liquid absorption function required for a cleanroom cloth and fails to meet the environmental requirements for rapid biodegradation.

[0040] Experimental Example 2: Tests on interlayer bond strength, hydrophilicity, and air permeability The interlayer bonding strength of Examples 1-5 and Comparative Examples 5-11 was tested according to GB / T 26203 standard; the hydrophilicity of Examples 1-5 and Comparative Examples 5-11 was tested according to the test method of Experimental Example 1; the air permeability of Examples 1-5 and Comparative Examples 5-11 was tested according to GB / T 24218.15 standard; the results are shown in Table 3.

[0041] Table 3. Interlayer bond strength, hydrophilicity, and air permeability of Examples 1-5 and Comparative Examples 5-11 Example <![CDATA[Interlayer bonding strength / J / m 2 > hydrophilicity / min <![CDATA[Air permeability / cm 3 / cm 2 / sec]]> Example 1 156 1.91 2.5 Example 2 150 2.05 2.8 Example 3 152 2.02 2.6 Example 4 153 1.98 2.6 Example 5 155 1.95 2.5 Comparative Example 5 178 6.51 8.2 Comparative Example 6 / 1.85 1.2 Comparative Example 7 162 8.45 0.8 Comparative Example 8 62 2.12 3.3 Comparative Example 9 85 12.53 2.5 Comparative Example 10 110 14.25 2.6 Comparative Example 11 108 2.24 2.5 ; Table 3 shows that Comparative Example 5, which directly composites the upper and lower spunbond layers, exhibits high interlayer bonding strength, even exceeding that of Example 1, due to the good homogeneity of polylactic acid and the coarse fibers and numerous contact points of the spunbond layer. However, this structure lacks the core absorbent sponge and filtration barrier of the meltblown layer; the capillary action of micro-nano fibers and modified starch is absent, resulting in significantly reduced hydrophilicity; simultaneously, the excessively large pore size of the spunbond layer leads to a surge in air permeability. Although the air permeability is excellent, this means it cannot effectively block micro-dust, thus losing the filtration function of the cleanroom cloth. Comparative Example 6 consists only of a thickened meltblown layer. Due to the absence of a layered structure, there is no interlayer delamination problem; although its hydrophilicity is excellent, its air permeability is low because the thickened meltblown layer causes dense fiber accumulation, increasing flow resistance; more seriously, the pure meltblown material, lacking the support of the spunbond layer skeleton, has extremely poor mechanical properties and cannot meet the strength requirements of actual wiping. Comparative Example 7, using hot melt adhesive spraying, exhibits high interlayer bonding strength sufficient to prevent delamination. However, its air permeability drops drastically because the continuous or semi-continuous adhesive film severely clogs the micropores between fibers, preventing air circulation. Simultaneously, the hydrophobic hot melt adhesive layer blocks the path of liquid penetration into the core layer, leading to prolonged hydrophilicity test time. Comparative Example 8 relies solely on subsequent hot pressing and weak chemical bonding, lacking physical entanglement. Data shows a significant reduction in its interlayer bonding strength. In practical use, this type of cleanroom cloth is prone to delamination and linting during wiping. Although it offers good air permeability, this permeability is based on an unstable structure. Comparative Example 9 underwent hydroentangling and padding, but omitted bio-enzyme activation. Because the polylactic acid surface itself lacks reactive groups, the crosslinking agent itaconic acid could not be effectively grafted onto the fiber surface, resulting in the inability to form chemical micro-soldering points. Its interlayer bonding strength was lower than that of Example 1, indicating that hydroentangling alone is insufficient to achieve optimal strength. Since hydrophilic groups were not grafted onto the surface, polylactic acid reverted to its hydrophobic nature, resulting in extremely poor hydrophilicity. Comparative Example 10 only underwent hydroentangling and enzyme treatment without padding. Although hydroentangling provided basic strength and enzyme treatment exposed some hydrophilic groups, the lack of a hydrophilic coating (polyether-modified silicone oil) and chemical crosslinking network resulted in poor surface hydrophilicity and a lack of contribution from chemical bonding to strength. The finishing solution of Comparative Example 11 contained only polyether-modified silicone oil and lacked itaconic acid and ammonium persulfate. The data showed that its hydrophilicity was good, close to that of Example 1, indicating that the silicone oil played a wetting role. However, its interlayer bonding strength was the same as that of Comparative Example 10 and much lower than that of Example 1. This strongly proves that itaconic acid and initiator did indeed undergo a cross-linking reaction during the heat setting process, forming enhanced chemical solder joints.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a biodegradable polyester cleanroom cloth, characterized in that, Includes the following steps: Masterbatch A is prepared using polylactic acid chips and modified nanocellulose, and masterbatch B is prepared using polybutylene succinate chips, the polylactic acid chips, and modified starch; the polylactic acid chips and masterbatch A are mixed and spunbonded to form upper and lower spunbonded layers. The polybutylene succinate chips, polylactic acid chips, and masterbatch B are mixed and meltblown to form a meltblown layer. The meltblown layer is placed between two spunbond layers and hot-pressed to obtain a multilayer material. The multilayer material is then subjected to hydroentangling reinforcement, enzyme activation, and padding treatment, and dried and baked to obtain the polyester cleanroom fabric. The masterbatch A is prepared by uniformly mixing the polylactic acid chips and the modified nanocellulose, feeding them into a twin-screw extruder, and then melt-blending, extruding, and granulating to obtain masterbatch A. The modified nanocellulose is prepared by dispersing nanocellulose crystals in anhydrous ethanol. In the process of ultrasonic dispersion, epoxidized soybean oil and p-toluenesulfonic acid are added, and the mixture is refluxed. After the reaction is completed, the product is separated by centrifugation, washed, and vacuum dried to obtain the modified nanocellulose. The preparation method of the masterbatch B is as follows: the polybutylene succinate chips, the polylactic acid chips and the modified starch are mixed, melt-blended and extruded to obtain the masterbatch B. The preparation method of the modified starch is as follows: the starch is dissolved in an acidic aqueous solution, glutaraldehyde is added dropwise, and the reaction is carried out at a constant temperature. Then, the pH is adjusted to alkaline with an alkali solution, maleic anhydride solution is added dropwise, the reaction is continued, and finally the pH is adjusted to neutral. The modified starch is obtained by spray drying.

2. The method for preparing a biodegradable polyester cleanroom cloth according to claim 1, characterized in that, The preparation method of the spunbond layer is as follows: the polylactic acid chips are mixed evenly with the masterbatch A and fed to the upper and lower spunbond spinning positions respectively. After the melt is sprayed out through the core-sheath composite component, it is solidified under side blowing cooling and the spunbond layer is formed by airflow stretching.

3. The method for preparing a biodegradable polyester cleanroom cloth according to claim 1, characterized in that, The method for preparing the meltblown layer is as follows: the polybutylene succinate chips, the polylactic acid chips and the masterbatch B are mixed evenly and fed to the meltblown die located between the two spunbond positions. The melt is drawn into fibers with an average diameter of 2-5 μm and sprayed onto the lower spunbond layer to form the meltblown layer.

4. The method for preparing a biodegradable polyester cleanroom cloth according to claim 1, characterized in that, The preparation method of the multilayer material is as follows: the upper spunbond layer is covered on the meltblown layer, and the three layers are pre-pressed by a pair of hot rolling rolls with a temperature of 75-85℃ and a linear pressure of 15-25kg / cm to obtain the multilayer material.

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