Composite flash-spun nonwoven fabric and method of making same

Abstract

The application discloses a composite flash non-woven fabric and a preparation method thereof, and belongs to the technical field of polymer materials. The method is characterized in that a PBAT material with a specific composition is used to form a film and construct a sandwich structure product of a PBAT layer-flash non-woven fabric layer-PBAT layer. The product with the composite structure has the mechanical strength of the flash non-woven fabric and the biological affinity and antibacterial property of the PBAT material. Subsequently, the product is subjected to a wrinkle treatment to generate surface textures with a simulation effect, and the product has a high fashion sense and is very suitable for the clothing field.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, specifically to a composite flash nonwoven fabric and its preparation method. Background Technology

[0002] Flash nonwoven fabric is a product made by instantaneously releasing polymer raw materials (mainly polyethylene) in a high-temperature and high-pressure environment to room temperature and pressure, thereby forming a film of spindle fibers. Compared with traditional synthetic nonwoven fabrics, it has higher strength and lighter weight.

[0003] However, compared to traditional nonwoven materials, flash-evaporated nonwoven fabrics are harder and have lower simulation. Furthermore, due to the characteristics of polyethylene, people are unwilling to have long-term direct contact with polyethylene plastic products. Therefore, there are currently few products that use flash-evaporated nonwoven fabrics in the clothing industry.

[0004] Biodegradable polyesters, led by PBAT (polybutylene terephthalate), are frequently used in food and pharmaceutical packaging, primarily due to their good processing performance, high biocompatibility and biodegradability, safety, and environmental friendliness. These materials often also contain PLA (polylactic acid), a natural antibacterial and antifungal agent that inhibits bacterial and mold growth in humid environments, theoretically making them ideal for clothing. However, the mechanical properties of biodegradable polyesters are generally inferior to non-biodegradable plastics such as polypropylene and polyethylene, making them highly susceptible to damage. Summary of the Invention

[0005] Based on the deficiencies of existing technologies, the purpose of this application is to provide a method for preparing composite flash nonwoven fabric. This method involves pre-forming a film of PBAT material with a specific composition and constructing a sandwich structure product consisting of a PBAT layer, a flash nonwoven fabric layer, and a PBAT layer. This composite structure product combines the mechanical strength of flash nonwoven fabric with the biocompatibility and antibacterial properties of PBAT material. Subsequently, a textured surface treatment is applied to create a product with a realistic effect, resulting in a high level of fashion and making it very suitable for the clothing industry.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] A method for preparing a composite flash nonwoven fabric includes the following steps:

[0008] A PBAT composite resin was prepared, and then blown into film to obtain a first PBAT film layer and a second PBAT film layer. The PBAT composite resin includes PBAT resin, polylactic acid, inorganic filler, and organic filler. The organic filler is sodium alginate cross-linked starch masterbatch, with an average particle size ≤3μm and a mass content of ≤5wt% in the PBAT composite resin.

[0009] The first PBAT film layer and the second PBAT film layer are respectively coated on both sides of the flash-evaporated nonwoven fabric, and the fabric is then degassed and hot-rolled to seal the edges, resulting in a composite base fabric.

[0010] The composite substrate is moistened in water, then placed in a texturing machine equipped with a heating system and rotated in both directions for the first texturing treatment. During the first texturing treatment, the drum speed of the texturing machine is 500-800 r / min, the temperature is 30-40℃, and the time is 10-15 min.

[0011] The composite base fabric, after undergoing the first texturing treatment, is immersed in water at 0–5°C for 5–10 minutes, and then placed back into the texturing machine for a second texturing treatment. During the second texturing treatment, the roller speed of the texturing machine is 900–1300 r / min, the temperature is 75–85°C, and the time is 2–4 minutes.

[0012] The composite base fabric after the second texturing treatment is cooled and dried to obtain the composite flash nonwoven fabric.

[0013] Preferably, the flash-evaporated nonwoven fabric is a polyethylene flash-evaporated nonwoven fabric.

[0014] Preferably, the average particle size of the organic filler is 1–3 μm.

[0015] Flash-woven nonwoven fabrics, especially polyethylene flash-woven nonwoven fabrics, possess significant advantages in clothing applications due to their unique manufacturing process and three-dimensional fiber composite structure. These advantages include high mechanical strength, excellent barrier properties, and lightweight construction. However, their inherently dry and uncomfortable texture, coupled with a smooth surface, makes them less fashionable when used in clothing. Existing nonwoven materials undergo a textured treatment to create leather-like effects and enhance their fashion appeal, resulting in a slightly fluffy and improved feel. However, given the inherent characteristics of flash-woven nonwoven fabrics, conventional textured treatments struggle to achieve a uniform and realistic texture. Increasing the intensity of the textured treatment can damage the surface, affecting the product's performance. Furthermore, current users generally perceive polyethylene as a toxic and environmentally unfriendly material, and are unlikely to wear clothing made entirely of polyethylene. Therefore, in this application's technical solution, the inventors first use an environmentally friendly PBAT resin-based film layer to coat flash-evaporated nonwoven fabric to form a composite base fabric. This eliminates people's prejudice against polyethylene materials. Even if polyethylene flash-evaporated nonwoven fabric may produce some toxic substances at high temperatures, these will be isolated by the PBAT film and will not come into direct contact with human skin. Simultaneously, the polylactic acid contained in the PBAT film layer has a certain antibacterial and antifungal effect. When the product is made into clothing, it can effectively improve the product's storage performance and prevent mold and mildew growth. Finally, PBAT resin is a biodegradable polyester with a certain degree of recyclability. Those skilled in the art can use recycled PBAT resin as a raw material when preparing the PBAT film layer, resulting in high environmental friendliness.

[0016] Meanwhile, to ensure that the composite flash-evaporated nonwoven fabric achieves the desired surface texture without compromising its performance, the inventors introduced sodium alginate-grafted starch masterbatch as an organic filler into the PBAT film layer. The prepared composite base fabric was then immersed in water. During this process, the sodium alginate-grafted starch masterbatch in the PBAT film layer absorbed water and swelled, rapidly filling the tiny pores between the PBAT film layer and the flash-evaporated nonwoven fabric. The fabric was then fed into a texturing machine for a specific two-step texturing process. During this process, the PBAT film acts as a buffer layer for the flash-evaporated nonwoven fabric, allowing for smooth transitions between low and high power settings. The segmented texturing process ensures that the surface of the flash-spun nonwoven fabric is fully textured without damaging it due to stress and gravity. On the other hand, since sodium alginate grafted starch masterbatch will expand, gelatinize, and fall off at high temperatures after absorbing water and swelling, and the texturing process will cause some thermal agglomeration in some areas, after the low-power, low-temperature texturing process, it is necessary to cool it in water (or an ice-water mixture) at 0-5°C. At this time, the initial texture on the surface of the flash-spun nonwoven fabric will also be quickly set, preventing the organic filler from falling off in a concentrated manner during the subsequent high-power texturing process.

[0017] Furthermore, the size of the organic filler in the PBAT film layer needs to be controlled within a specific range. Otherwise, if the organic filler is too large during high-power texturing, the expansion, gelatinization, and detachment of the sodium alginate-grafted starch masterbatch may lead to uneven texturing, or local agglomeration and adhesion may damage the composite film layer, ultimately affecting the product's performance. On the other hand, since the detachment of the impregnated organic filler is inevitable during high-power texturing, excessive content will not only fail to effectively act as an interlayer adsorbent but may also cause increased interlayer porosity due to detachment and agglomeration, even exposing parts of the flash-evaporated nonwoven fabric, resulting in a poor product finish.

[0018] Preferably, the heating system of the kneading machine includes at least one of a hot air heating system and a steam heating system.

[0019] More preferably, the heating system of the kneading machine has a heating rate of ≥5℃ / min.

[0020] More preferably, the heating system of the kneading machine has a heating rate of 5-8°C / min.

[0021] When heating the composite base fabric inside the folding machine using different preheating rates, if the heating time is too long, the flash fiber expansion time in the composite base fabric will be too long. At the same time, the probability of the organic filler impregnated in the PBAT film falling off is higher in the high temperature and high power stage, which will have a greater impact on the protective effect of the product.

[0022] Preferably, the PBAT composite resin comprises the following components in parts by weight:

[0023] The mixture contains 80-85 parts of PBAT resin, 5-10 parts of polylactic acid, 6-9 parts of inorganic filler, and 1-4 parts of organic filler.

[0024] More preferably, the PBAT resin has a melt index of 5 to 10 g / min, a test load of 2.16 kg, and a test temperature of 190 °C, as tested according to ISO 1133-2011.

[0025] More preferably, the PBAT resin includes at least one of virgin material and recycled material.

[0026] Since the mechanical properties of the product in this application mainly come from the flash-evaporated nonwoven fabric, based on actual needs, those skilled in the art can use virgin PBAT to prepare the film layer, or use recycled materials or other recycled materials (such as virgin PBAT made from recycled PET waste) as the matrix resin for preparation. It has been verified that this will not affect the performance of the product or cause significant differences in the texture effect.

[0027] More preferably, the melt index of polylactic acid, as tested according to ISO 1133-2011, is 1 to 10 g / min, the test load is 2.16 kg, and the test temperature is 190 °C.

[0028] More preferably, the average particle size of the inorganic filler is 1–3 μm.

[0029] More preferably, the inorganic filler includes at least one of talc, montmorillonite, wollastonite, calcite, granite, kaolin, air-knife clay, titanium dioxide, silicon dioxide, mica powder, and glass fiber.

[0030] More preferably, the sodium alginate cross-linked starch masterbatch can be prepared by cross-linking commercially available starch masterbatch with sodium alginate, or by cross-linking starch with sodium alginate and then preparing it into masterbatch form. It should be noted that both methods can obtain sodium alginate cross-linked starch masterbatch, and such masterbatch can exhibit the expected adsorption and expansion properties, while having relatively good stability, which can enable the composite base fabric to achieve the ideal technical effect after texture treatment.

[0031] More preferably, the method for preparing sodium alginate cross-linked starch masterbatch includes the following steps:

[0032] Starch and sodium alginate were mixed in water, and the pH of the resulting mixture was adjusted to 9-10. A cross-linking agent was added, and a cross-linking reaction was carried out. After the reaction was completed, the pH of the resulting mixture was adjusted to 6.5-7.5, the solid and liquid were separated, and the mixture was dried to obtain sodium alginate cross-linked starch.

[0033] Sodium alginate cross-linked starch and additives are mixed and stirred, extruded and granulated using a twin-screw extruder, and then sieved to obtain sodium alginate cross-linked starch masterbatch.

[0034] More preferably, the starch is plant starch, and the plant starch is at least one of corn starch, wheat starch, and potato starch.

[0035] More preferably, the additives include at least one of plasticizers, solvents, compatibilizers, fillers, and lubricants.

[0036] More preferably, the sodium alginate cross-linked starch content in the sodium alginate cross-linked starch masterbatch is ≥95wt%.

[0037] More preferably, the temperature of the crosslinking reaction is 20–40°C and the time is 1–2 hours.

[0038] Preferably, the mass ratio of starch to sodium alginate is 1:(0.1-0.2).

[0039] Sodium alginate can improve the stability and adsorption properties of starch after grafting, making the PBAT film layer adhere better to the flash nonwoven fabric after wetting. This is more conducive to ensuring that the flash nonwoven fabric will not be seriously damaged during the folding process. However, if too much sodium alginate is grafted, its overall viscosity will increase, especially during the high-temperature and high-power folding process, which can easily lead to gelatinization and denaturation, resulting in detachment and agglomeration. Therefore, it is more effective to prepare the raw materials and sodium alginate cross-linked starch masterbatch with the above-mentioned mass ratio of starch and sodium alginate.

[0040] Preferably, the PBAT composite resin is prepared by mixing the components and then placing them in a twin-screw extruder for melt extrusion at 160-180°C to obtain the PBAT composite resin.

[0041] Preferably, the temperature during PBAT composite resin blown film blowing is 120–150°C.

[0042] Preferably, in the composite base fabric, the thickness ratio of the first PBAT film layer, the flash nonwoven fabric and the second PBAT film layer is (0.8~1.2):3:(0.8~1.2).

[0043] Preferably, the temperature during hot rolling edge sealing is 300–360°C and the pressure is 10–30 N.

[0044] Another objective of this application is to provide a method for preparing the composite flash nonwoven fabric to obtain the composite flash nonwoven fabric.

[0045] Preferably, the composite flash nonwoven fabric has a tensile strength of 6-7 kN / m and an elongation at break of 25-30% as tested according to GB / T 12914-2018 (sample width 25.4 mm, tensile rate 100 mm / min, MD).

[0046] Preferably, the tear strength of the composite flash nonwoven fabric, tested according to GB / T 4744-2013 (constant radius cutting method, MD), is 10-11N.

[0047] Preferably, the composite flash nonwoven fabric has a basis weight of 160–180 g / m² as tested according to GB / T 451.2-2002. 2 .

[0048] Another object of this application is to provide the application of the composite flash nonwoven fabric in the preparation of clothing products.

[0049] The beneficial effect of this application is that it provides a composite flash nonwoven fabric and its preparation method. The method pre-forms a film with a PBAT material of a specific composition and constructs a sandwich structure product of PBAT layer-flash nonwoven fabric layer-PBAT layer. This composite structure product combines the mechanical strength of flash nonwoven fabric with the biocompatibility and antibacterial properties of PBAT material. Subsequently, the product is textured by crumpling to produce a surface texture with a realistic effect, which is highly fashionable and very suitable for the clothing industry. Detailed Implementation

[0050] To better illustrate the purpose, technical solution, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, aims to provide a detailed understanding of the content of this application, rather than limiting it. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this application are commonly used reagents and instruments. The flash-spun nonwoven fabric used in this application is the same polypropylene flash-spun nonwoven fabric material used in the applicant's prior flash-spun fabric preparation of Rowellk protective clothing. The vertical roller kneading machine is a commercially available product with a hot air heating system. The meltblown machine is a commercially available product with a meltblown nozzle, traction belt, and collection net.

[0051] Example 1

[0052] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application includes the following steps:

[0053] (1) Prepare PBAT composite resin, and then blow film at 145℃ using a blown film machine to obtain the first PBAT film layer and the second PBAT film layer. The PBAT composite resin, in 100 parts, includes 80 parts PBAT resin, 10 parts polylactic acid, 6 parts inorganic filler and 4 parts organic filler. The melt index of the PBAT resin, tested according to ISO 1133-2011, is 6 g / min. The PBAT resin is THJS-7801 produced by Lanshan Tunhe. The polylactic acid is prepared according to ISO 1133-2011. The melt flow index of 1133-2011 was 8 g / min, and the product was produced by Prak. The inorganic filler was talc powder with an average particle size of 3 μm, and the organic filler was sodium alginate cross-linked starch masterbatch. The preparation method was as follows: 99 wt% sodium alginate cross-linked starch and 1 wt% auxiliary agent (commercially available lubricant erucamide) were mixed and stirred, and extruded and granulated using a twin-screw extruder at 100-180℃ (screw speed 400 rpm). After sieving, sodium alginate cross-linked starch masterbatch with an average particle size of 2 μm was obtained.

[0054] The preparation method of sodium alginate cross-linked starch is as follows: Corn starch and sodium alginate are mixed in water at a mass ratio of 1:0.2. The pH of the resulting mixture is then adjusted to 10. A cross-linking agent, phosphorus oxychloride (1 wt% of the total mass of starch and sodium alginate), is added, and the mixture is subjected to a cross-linking reaction at 30°C for 1.5 hours. After the reaction is complete, the pH of the resulting mixture is adjusted to 7, the solid and liquid are separated, and the mixture is dried to obtain sodium alginate cross-linked starch.

[0055] The preparation method of PBAT composite resin is as follows: mix the components, then put them into a twin-screw extruder and melt-extrude at 160-180℃ (screw speed 400rpm) to obtain PBAT composite resin.

[0056] (2) The first PBAT film layer and the second PBAT film layer are respectively covered on both sides of the flash nonwoven fabric, and the air is extracted and hot rolling edge sealing is performed at 350℃ and 20N to obtain the composite base fabric. The thickness ratio of the first PBAT film layer, the flash nonwoven fabric layer and the second PBAT film layer in the obtained composite base fabric is 1:3:1.

[0057] (3) The composite base is wetted in water and then placed in a kneading machine with a heating system and rotated in both directions to perform the first kneading treatment. During the first kneading treatment, the drum speed of the kneading machine is 600 r / min, the temperature is 35℃, and the time is 12 min. The heating rate of the kneading machine is 5℃ / min.

[0058] (4) The composite base fabric after the first texturing treatment is immersed in water at 3°C ​​for 10 minutes, and then put back into the texturing machine for the second texturing treatment. During the second texturing treatment, the roller speed of the texturing machine is 1000 r / min, the temperature is 80°C, and the time is 3 minutes.

[0059] (5) Cool and dry the composite base fabric after the second texturing treatment to obtain the composite flash nonwoven fabric.

[0060] Example 2

[0061] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application includes the following steps:

[0062] (1) Same as step (1) in Example 1;

[0063] (2) Same as step (2) in Example 1;

[0064] (3) The composite substrate is moistened in water, and then placed in a texturer with a heating system and rotated in both directions for the first texture treatment. During the first texture treatment, the drum speed of the texturer is 700 r / min, the temperature is 35℃, and the time is 11 min.

[0065] (4) The composite base fabric after the first texturing treatment is immersed in water at 3°C ​​for 10 minutes, and then placed back into the texturing machine for the second texturing treatment. During the second texturing treatment, the roller speed of the texturing machine is 1100 r / min, the temperature is 80°C, and the time is 4 minutes.

[0066] (5) Cool and dry the composite base fabric after the second texturing treatment to obtain the composite flash nonwoven fabric.

[0067] Example 3

[0068] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the PBAT composite resin, calculated per 100 parts, comprises 85 parts PBAT resin, 5 parts polylactic acid, 7 parts inorganic filler, and 3 parts organic filler. The polylactic acid has a melt flow index of 5 g / min as tested according to ISO 1133-2011 and is manufactured by Natureworks (USA) as 4043D. The inorganic filler is wollastonite with an average particle size of 2 μm.

[0069] Example 4

[0070] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the heating rate of the tweening machine is 6°C / min.

[0071] Example 5

[0072] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the heating rate of the tweening machine is 8°C / min.

[0073] Example 6

[0074] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the heating rate of the tumbling machine is 3℃ / min.

[0075] Example 7

[0076] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that, during the preparation of sodium alginate crosslinked starch, starch and sodium alginate are added at a mass ratio of 1:0.1.

[0077] Example 8

[0078] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that, during the preparation of sodium alginate crosslinked starch, starch and sodium alginate are added at a mass ratio of 1:0.05.

[0079] Example 9

[0080] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that, during the preparation of sodium alginate crosslinked starch, starch and sodium alginate are added at a mass ratio of 1:0.5.

[0081] Example 10

[0082] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the average particle size of the sodium alginate cross-linked starch masterbatch is 1 μm.

[0083] Example 11

[0084] An embodiment of the composite flash nonwoven fabric and its preparation method described in this application differs from Embodiment 1 only in that the average particle size of the sodium alginate cross-linked starch masterbatch is 3 μm.

[0085] Comparative Example 1

[0086] A composite flash nonwoven fabric and its preparation method include the following steps:

[0087] (1) Same as step (1) in Example 1;

[0088] (2) Same as step (2) in Example 1;

[0089] (3) The composite base is wetted in water and then placed in a texturer with a heating system and rotated in both directions to perform texture treatment. During the texture treatment, the drum speed of the texturer is 600 r / min, the temperature is 35℃, and the time is 15 min. The heating rate of the texturer is 5℃ / min.

[0090] (4) Cool and dry the composite base fabric after the texturing treatment to obtain the composite flash nonwoven fabric.

[0091] Comparative Example 2

[0092] A composite flash nonwoven fabric and its preparation method include the following steps:

[0093] (1) Same as step (1) in Example 1;

[0094] (2) Same as step (2) in Example 1;

[0095] (3) The composite base is wetted in water and then placed in a texturer with a heating system and rotated in both directions to perform texture treatment. During the texture treatment, the drum speed of the texturer is 1000 r / min, the temperature is 80℃, and the time is 15 min. The heating rate of the texturer is 5℃ / min.

[0096] (4) Cool and dry the composite base fabric after the texturing treatment to obtain the composite flash nonwoven fabric.

[0097] Comparative Example 3

[0098] A composite flash nonwoven fabric and its preparation method include the following steps:

[0099] (1) Same as step (1) in Example 1;

[0100] (2) Same as step (2) in Example 1;

[0101] (3) Same as step (3) in Example 1;

[0102] (4) The composite substrate after the first texturing treatment is placed into the texturing machine for the second texturing treatment. During the second texturing treatment, the drum speed of the texturing machine is 1000 r / min, the temperature is 80℃, and the time is 3 min.

[0103] (5) Same as step (5) in Example 1.

[0104] Comparative Example 4

[0105] A composite flash nonwoven fabric and its preparation method differ from Example 1 only in that the temperature during the first crumpling treatment is 80°C.

[0106] Comparative Example 5

[0107] An embodiment of a composite flash nonwoven fabric and its preparation method differs from Embodiment 1 only in that the organic filler is replaced by talc powder with an average particle size of 2 μm.

[0108] Comparative Example 6

[0109] An embodiment of a composite flash nonwoven fabric and its preparation method differs from Example 1 only in that the organic filler is starch masterbatch. The preparation method is as follows: 99 wt% starch and 1 wt% auxiliary agent (commercially available lubricant erucamide) are mixed and stirred, extruded and granulated using a twin-screw extruder at 100-180°C (screw speed 400 rpm), and sieved to obtain starch masterbatch with an average particle size of 2 μm.

[0110] Comparative Example 7

[0111] An embodiment of a composite flash nonwoven fabric and its preparation method differs from Example 1 only in that the average particle size of the sodium alginate cross-linked starch masterbatch is 5 μm.

[0112] Comparative Example 8

[0113] An embodiment of a composite flash nonwoven fabric and its preparation method differs from Embodiment 1 only in that 100 parts of PBAT composite resin include 80 parts of PBAT resin, 10 parts of polylactic acid, and 10 parts of organic filler.

[0114] Comparative Example 9

[0115] An embodiment of a composite flash nonwoven fabric and its preparation method differs from Embodiment 1 only in that 100 parts of PBAT composite resin include 70 parts of PBAT resin, 10 parts of polylactic acid, 12 parts of inorganic filler, and 8 parts of organic filler.

[0116] Example of effect

[0117] To verify the performance of the composite flash nonwoven fabric described in this application, the following tests were conducted on the products of each embodiment and comparative example:

[0118] (1) Appearance three-dimensional texture test: Using commercially available cowhide leather as a reference, five people in a group scored the appearance three-dimensional texture of each example and comparative product. The average score was taken and statistically analyzed. The scoring criteria are as follows:

[0119] The highest score is 5 points, and the lowest score is 1 point.

[0120] 5 points: The texture is even and three-dimensional.

[0121] 4 points: The texture is uniform and relatively three-dimensional, or the texture is three-dimensional and relatively uniform.

[0122] 3 points: The texture is relatively three-dimensional and even.

[0123] 2 points: The texture is uneven or lacks definition.

[0124] 1 point: The texture is uneven and lacks three-dimensionality.

[0125] (2) Tensile strength & elongation at break retention rate test: Before each embodiment and comparative example was implemented, the untreated composite base fabric was tested according to GB / T 12914-2018 (sample width 25.4 mm, tensile rate 100 mm / min, MD). The tensile strength of each untreated composite base fabric was measured to be 7-7.5 kN / m and the elongation at break was 25-35%, which met the test conditions. The tensile strength and elongation at break test values ​​of the untreated composite base fabric of each embodiment and comparative example were calibrated as initial values. Subsequently, the same test was performed on the composite flash nonwoven fabric obtained after each embodiment and comparative example was implemented, and the tensile strength & elongation at break retention rate (%) was calculated based on the initial values ​​= tensile strength & elongation at break of composite flash nonwoven fabric / initial value × 100%.

[0126] (3) Tear retention rate test: Before each embodiment and comparative example was implemented, the untreated composite base fabric was tested according to GB / T 4744-2013 (constant radius cutting method, MD). The tensile strength of each untreated composite base fabric was measured to be 10.5~11.5N, which met the test conditions. The tear test value of the untreated composite base fabric of each embodiment and comparative example was calibrated as the initial value. Then, the same test was performed on the composite flash nonwoven fabric obtained after each embodiment and comparative example was implemented. The tear retention rate (%) was calculated based on the initial value = tear value of composite flash nonwoven fabric / initial value × 100%.

[0127] The test results are shown in Table 1.

[0128] Table 1

[0129]

[0130]

[0131]

[0132]

[0133] The results show that the composite flash-evaporated nonwoven fabric described in this application has an excellent appearance and a good leather texture effect. The appearance score of the products in each embodiment can reach 4 points or above, and in terms of fashion, it can be applied in the clothing industry. At the same time, after the crumpling treatment, the mechanical properties of the composite flash-evaporated nonwoven fabric are basically maintained at a high level. The tensile strength can be maintained at more than 85% of the original strength, reaching 6-7 kN / m; the elongation at break can be maintained at more than 80% of the original strength, reaching 25-30%; and the tear strength can be maintained at more than 90% of the original strength, reaching more than 10 N.

[0134] According to the performance results of the products in Examples 1 and 4-6, it can be seen that the heating rate during the texturing process determines the overall heating time of the composite base fabric. If the heating time is too long, it may increase the probability of organic fillers falling off in the PBAT film layer, thereby affecting the performance level of the product. A heating rate of 5℃ / min or higher for the texturing machine is more effective.

[0135] As can be seen from Examples 1 and 7-9, as well as Comparative Example 6, whether the starch masterbatch in the PBAT film layer is modified with sodium alginate grafting has a decisive effect on the product performance. Without sodium alginate grafting modification, the stability and adsorption of the starch masterbatch are poor, making it impossible for the PBAT film layer to provide sufficient adhesion and protection to the flash-evaporated nonwoven fabric during the texturing process. Not only is the texturing effect poor, but the performance of the product after texturing is significantly reduced compared to before texturing, as shown in Comparative Example 6. As shown, the tensile strength retention rate after crumpling is only 84.2%. With the grafting of sodium alginate, the starch masterbatch can fully absorb water, swell, and adsorb between layers, improving the protective effect on the flash-evaporated nonwoven fabric. However, since the grafting of sodium alginate will change the viscosity of the masterbatch to a certain extent, if too much grafting is done, the probability of masterbatch shedding and agglomeration during high-power crumpling will increase to a certain extent. Therefore, when preparing sodium alginate-grafted starch masterbatch, the mass ratio of sodium alginate to starch is 1:(0.1~0.2) for the best effect.

[0136] As can be seen from Examples 1, 10-11 and Comparative Example 7, when used as a filler in the PBAT film layer, the size of the sodium alginate grafted starch masterbatch also affects the final performance of the product. The size cannot be too large, otherwise, as shown in Comparative Example 7, not only will the appearance score be less than 4 points, but the tensile strength, elongation at break and tearing degree will also be at a low level after the crumpling treatment.

[0137] Comparative Example 1 and Comparative Example 2 employed a traditional one-step texturing process after constructing the composite base fabric. The former used low-power texturing conditions, while the latter used high-power conditions. The results showed that the texturing effect of Comparative Example 1 was poor, failing to achieve the expected texture effect. Although the texture of Comparative Example 2 was deeper, its uniformity was poor, mainly due to excessive and uneven texturing. Therefore, the product scored less than 4 points, and its performance degradation was high, with the lowest tensile strength, elongation at break, and tear strength among all products after texturing.

[0138] Comparative Example 3 product was subjected to segmented creping based on Comparative Examples 1 and 2, but water cooling was not used in the intermediate process. The product's appearance reached 4 points, but the performance retention rate was lower than that of the product in Example 1, especially the tensile strength, which was only 82.8% after creping.

[0139] Compared to Example 1, the product of Comparative Example 4 was 80°C during segmented kneading. Under such high temperature conditions, the organic filler in the PBAT film layer expanded and gelatinized to a high degree. The results showed that its performance was comparable to that of the product of Comparative Example 2, indicating that in addition to kneading power, kneading temperature must also be specifically limited during segmented kneading.

[0140] Comparative Example 5 did not introduce organic fillers, but instead used a traditional inorganic filler system to prepare the PBAT film layer. Compared with the organic filler composite film layer, its adsorption and protection of flash nonwoven fabric were not high. The appearance score of the prepared product was only 3.6 points, and the retention rate of various properties after crumpling was low.

[0141] However, the introduction of organic fillers should not be excessive, because during high-power texturing, the expansion, gelatinization, and shedding of organic fillers are inevitable. If too much is introduced, the amount of shedding will also increase, which will cause the composite base fabric to stick together during texturing, resulting in uneven texturing effect of the product. As shown in Comparative Examples 8 and 9, regardless of whether the content of the matrix PBAT resin changes, if the content of organic fillers exceeds 5wt%, the performance of the product is not ideal.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A method for preparing a composite flash-evaporated nonwoven fabric, characterized in that, Includes the following steps: A PBAT composite resin was prepared, and then blown into a first PBAT film layer and a second PBAT film layer. The PBAT composite resin included PBAT resin, polylactic acid, inorganic filler, and organic filler. The organic filler was sodium alginate cross-linked starch masterbatch, the average particle size of the organic filler was less than or equal to 3 μm, and the mass content of the organic filler in the PBAT composite resin was less than or equal to 5 wt%. The first PBAT film layer and the second PBAT film layer are respectively covered on both sides of the flash-evaporated nonwoven fabric, and the air is extracted and hot-rolled edge sealing is performed to obtain the composite base fabric. The composite substrate is moistened in water and then placed in a kneading machine with a heating system and rotated in both directions to perform the first kneading treatment. During the first kneading treatment, the drum speed of the kneading machine is greater than or equal to 500 r / min and less than or equal to 800 r / min, the temperature is greater than or equal to 30℃ and less than or equal to 40℃, and the time is greater than or equal to 10 min and less than or equal to 15 min. The composite base fabric after the first texturing treatment is immersed in water at 0~5℃ for 5~10 minutes, and then put back into the texturing machine for the second texturing treatment. During the second texturing treatment, the roller speed of the texturing machine is greater than or equal to 900 r / min and less than or equal to 1300 r / min, the temperature is greater than or equal to 75℃ and less than or equal to 85℃, and the time is greater than or equal to 2 minutes and less than or equal to 4 minutes. The composite base fabric after the second texturing treatment is cooled and dried to obtain the composite flash nonwoven fabric.

2. The method for preparing the composite flash nonwoven fabric as described in claim 1, characterized in that, The heating system of the kneading machine has a heating rate of 5℃ / min or greater.

3. The method for preparing the composite flash nonwoven fabric as described in claim 1, characterized in that, The PBAT composite resin comprises the following components in parts by weight: 80-85 parts PBAT resin, 5-10 parts polylactic acid, 6-9 parts inorganic filler, and 1-4 parts organic filler.

4. The method for preparing the composite flash nonwoven fabric as described in claim 1, characterized in that, The method for preparing sodium alginate cross-linked starch masterbatch, Includes the following steps, Starch and sodium alginate were mixed in water, and the pH of the resulting mixture was adjusted to 9-10. A cross-linking agent was added and a cross-linking reaction was carried out. After the reaction was completed, the pH of the resulting mixture was adjusted to 6.5-7.5, the solid and liquid were separated, and the mixture was dried to obtain sodium alginate cross-linked starch. The sodium alginate cross-linked starch and additives are mixed and stirred, extruded and granulated using a twin-screw extruder, and then sieved to obtain sodium alginate cross-linked starch masterbatch.

5. The method for preparing the composite flash nonwoven fabric as described in claim 4, characterized in that, The mass ratio of starch to sodium alginate is 1:(0.1~0.2).

6. The method for preparing the composite flash nonwoven fabric as described in claim 1, characterized in that, In the composite base fabric, the thickness ratio of the first PBAT film layer, the flash nonwoven fabric and the second PBAT film layer is (0.8~1.2):3:(0.8~1.2).

7. The composite flash nonwoven fabric prepared by the method described in any one of claims 1 to 6.

8. The composite flash nonwoven fabric as described in claim 7, characterized in that, The composite flash nonwoven fabric has a tensile strength greater than or equal to 6 kN / m and less than or equal to 7 kN / m as tested according to GB / T12914-2018.

9. The composite flash nonwoven fabric as described in claim 7, characterized in that, The composite flash nonwoven fabric has a breaking elongation of greater than or equal to 25% and less than or equal to 30% as tested according to GB / T12914-2018.

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