A wet-laid spunlace nonwoven fabric of cotton gauze and pulp composite and a preparation method thereof
By combining natural cellulose fiber pulp with cotton yarn and using a special hydroentangling process, the problems of low composite strength and large differences between the two sides of nonwoven fabric and cotton yarn were solved, and high-strength and uniform nonwoven fabric was prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUYANG WEIYE BASE CLOTH CO LTD
- Filing Date
- 2022-04-28
- Publication Date
- 2026-05-15
AI Technical Summary
The existing composite strength of nonwoven fabric and cotton yarn is low, and there is a significant difference between the two sides.
The composite material is made of natural cellulose fiber pulp and cotton yarn, combined with a special hydroentangling process, including pre-hydroentangling and reverse hydroentangling. By utilizing the irregular surface characteristics of the pulp fiber, the composite strength is improved and the difference between the two sides is reduced through the reduction of hydroentangling pressure on the front side and the use of hydroentangling support curtains woven from coarse denier polyester yarn.
It improves the composite strength of cotton yarn and wet fiber layer, reduces pulp fiber loss, lowers production costs, and eliminates the need to distinguish between the front and back sides when using nonwoven fabric.
Smart Images
Figure CN116411385B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite nonwoven fabrics, and more particularly to a method for preparing a wet-process spunlace nonwoven fabric composed of cotton yarn and pulp. Background Technology
[0002] Composite nonwoven fabrics are comprehensive fabrics obtained by combining two or more nonwoven fabrics (or other textiles or plastics) with different properties through chemical, thermal, or mechanical methods. They integrate the superior properties of multiple materials, and by combining the strengths and weaknesses of various composite materials, the overall performance of the product is fully improved. As a type of composite nonwoven fabric, the combination of nonwoven fabric and cotton yarn combines the advantages of both. The cotton yarn imparts water absorption, stain removal, and dimensional stability to the composite fabric, while the nonwoven fabric improves the softness, comfort, water absorption, moisture retention, and physical barrier properties of the yarn.
[0003] Currently, in composite fabrics of nonwoven fabric and cotton yarn, the common method is to combine regenerated cellulose fibers with cotton yarn. For example, patent CN108790316B discloses a composite fabric of tansil fiber and cotton yarn and its preparation method. The composite fabric is made through the following process: (1) Raw material mixing: water and Tencel fibers are mixed evenly to obtain a slurry, wherein the mass percentage concentration of Tencel fibers in the slurry is 0.3-0.35%; (2) Fiber web formation: the slurry is fed into an inclined web forming device, and a web fiber layer is obtained after the inclined web is formed; (3) Lamination: the web fiber layer is conveyed downward by an upper conveyor network. After being dewatered by a vacuum adsorption roller, the primary composite fabric is bonded to the base fabric conveyed horizontally by the lower conveyor network; (4) Pre-punching: The primary composite fabric is hydroentangled by the first hydroentanglement machine to obtain the intermediate composite fabric; (5) Hydroentanglement: The intermediate composite fabric is further conveyed to the hydroentanglement unit for hydroentanglement, and after hydroentanglement, a semi-finished composite fabric is obtained; (6) Dewatering and shaping: The semi-finished composite fabric is dewatered by a dewatering roller, rolled up and finished, and finally dried and shaped to obtain the finished composite fabric of tansil fiber and cotton yarn. This patent uses wet hydroentanglement to composite and entangle tansil fiber and cotton yarn together, so that the product has the advantages of both materials at the same time, and fully presents the physical property effect of 1+1>2. However, the inventors' team discovered that the composite nonwoven fabrics of this type of regenerated cellulose fiber and cotton gauze generally have the following problems: the surface of the regenerated cellulose fiber is smooth or has regular stripes, and because the surface is already shaped, it is difficult to form a large number of cracks and fibers on the surface even if it is broken down. Therefore, the composite strength between the fiber and cotton gauze is low, and the bonding state is easily damaged. Summary of the Invention
[0004] To address the problem of low composite strength between nonwoven fabrics and cotton yarn in existing technologies, this invention provides a wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, and its preparation method. This invention uses natural cellulose fiber pulp to composite with cotton yarn, achieving high composite strength between the cotton yarn and the wet-laid fiber layer. Furthermore, the invention employs a special hydroentangling process in the preparation of the wet-laid spunlace nonwoven fabric, which enhances the composite strength between the cotton yarn and the wet-laid fiber layer and results in a less noticeable difference between the two sides of the obtained wet-laid spunlace nonwoven fabric.
[0005] The specific technical solution of this invention is as follows:
[0006] In a first aspect, the present invention provides a wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, comprising intertwined cotton yarn and a wet-laid fiber layer; wherein the wet-laid fiber layer is formed by wet-laid web formation of natural cellulose fiber pulp.
[0007] Natural cellulose fiber pulp is a fibrous aggregate. After studying natural cellulose fiber pulp and regenerated cellulose fibers, our team discovered that, unlike the smooth or regularly striped surface of regenerated cellulose fibers, pulp fibers have irregular uneven surfaces with scales, horizontal and vertical lines, and spiral patterns, and are prone to producing fluff and cracks when broken down. Based on this, our invention uses a wet-laid fiber layer made from pulp combined with cotton yarn. This utilizes the unique surface properties of pulp fibers to generate greater friction between the wet-laid fiber layer and the cotton yarn, thereby increasing the composite strength and making the bond less prone to damage.
[0008] Preferably, the natural cellulose fiber pulp includes one or more of wood pulp, cotton pulp, hemp pulp, and bamboo pulp.
[0009] Secondly, the present invention provides a method for preparing the wet-laid spunlace nonwoven fabric, comprising the following steps:
[0010] (1) Natural cellulose fiber pulp is broken down to create cracks and fluff on the fiber surface to obtain a fiber suspension.
[0011] (2) The fiber suspension is wet-laid to obtain a wet-laid fiber web;
[0012] (3) The wet-laid fiber web is stacked with cotton yarn and pre-hydroentangled to obtain a pre-entangled composite fabric;
[0013] (4) Perform 4 to 6 passes of hydroentanglement with decreasing pressure on the front side of the pre-spun composite fabric, and then perform 0 to 2 passes of hydroentanglement on the reverse side to obtain the hydroentangled composite fabric.
[0014] (5) Dry the spunlace composite fabric to obtain a wet spunlace nonwoven fabric composed of cotton yarn and pulp.
[0015] This invention designs a composite process based on the special properties of natural cellulose fiber pulp to achieve high composite strength between the wet-laid fiber layer and the cotton yarn, and to obtain a wet-laid spunlace nonwoven fabric with minimal two-sided difference, eliminating the need to distinguish between the front and back sides during use. Specifically:
[0016] ① In the present invention, when compounding pulp and cotton yarn, after a portion of the fibers are displaced and interwoven through pre-hydraulic spunlace, front-side and back-side spunlace are performed sequentially. The purpose is as follows: through front-side spunlace, the fibers in the wet-laid fiber web can be inserted into the pores of the cotton yarn and entangled with the warp and weft yarns of the cotton yarn to form a composite. During this process, some fiber hairs in the wet-laid fiber web will penetrate to the other side of the cotton yarn. Then, through back-side spunlace, the fiber hairs that have penetrated to the other side of the cotton yarn can be returned to the cotton yarn, thereby improving the entanglement strength.
[0017] ② In the process of hydroentangling on the front side, the hydroentangling pressure decreases progressively. This serves two purposes: First, in the pre-spunlace composite fabric, the pulp fibers are not yet entangled and are in a loose state. At this stage, a higher hydroentangling pressure allows the pulp fibers to penetrate the cotton yarn and form a displacement and interweaving pattern. Then, a lower hydroentangling pressure is used to cause the pulp fibers to entangle with each other. This method, by first allowing the pulp fibers to displace and interweave with the cotton yarn, and then allowing them to entangle with each other, facilitates the effective implantation of pulp fibers into the pores of the cotton yarn, reduces the two-sided difference of the wet-spunlace nonwoven fabric, and also helps to reduce pulp fiber loss, improve product yield, and reduce production costs.
[0018] Preferably, in step (1), the degree of dissociation of the fiber suspension is 10-20°SR.
[0019] When the degree of beating is 10-20°SR, the surface of the pulp fiber breaks down and separates into fine fibers. These cracks and fibers can be used to achieve a high composite strength between the cotton yarn and the pulp fiber.
[0020] Preferably, in step (1), before crushing, the solid content in the natural cellulose fiber pulp is adjusted to 4-7 wt%; the crushing is carried out by an intermittent crushing method, the crushing time is 1-2 min each time, crushing once every 50-90 s, and the number of crushing times is 3-5 times.
[0021] This invention employs a high-concentration intermittent pulping technology, which, while breaking down pulp into fibers, generates more cracks and fluff on the fiber surface, thereby improving the composite strength between cotton yarn and pulp fibers.
[0022] Preferably, in step (4), the hydroentangling pressure of the front hydroentangling is 25-55 bar, wherein the hydroentangling pressure of the first front hydroentangling is 40-55 bar.
[0023] During the hydroentangling process, the first hydroentangling step is used to create displacement and interpenetration between the pulp fibers and the cotton yarn. If the hydroentangling pressure of the first hydroentangling step is too low, the displacement distance of the pulp fibers will be too small, making it difficult for them to fully penetrate the cotton yarn and causing most of them to float on the surface of the cotton yarn, resulting in obvious differences between the two sides of the wet hydroentangled nonwoven fabric. On the other hand, if the hydroentangling pressure of the first hydroentangling step is too high, it will cause excessive loss of pulp fibers.
[0024] The hydroentanglement pressure of subsequent front hydroentanglement processes will also affect the performance of the final wet hydroentangled nonwoven fabric. When the hydroentanglement pressure is too low, it will be difficult for the pulp fibers to fully entangle, affecting the strength of the wet hydroentangled nonwoven fabric.
[0025] Preferably, in step (4), the hydroentangling pressure of the reverse hydroentangling is 30 to 60 bar.
[0026] Preferably, in step (4), the front hydroentangling process is carried out on a hydroentangling support screen with an aperture of 100 to 110 mesh; the hydroentangling support screen is woven from coarse denier polyester yarn with a diameter of 0.18 to 0.22 mm.
[0027] Using a spunlace support curtain (single-layer polyester filament) woven from coarse denier polyester filaments with a diameter of 0.18–0.22 mm is beneficial for reducing the two-sided difference of wet-laid spunlace nonwoven fabric. This is because the spunlace support curtain woven from coarse denier polyester filaments has a larger height difference space in the cross-sectional direction, which can provide more space for the pulp fibers to displace and penetrate into the pores of the cotton yarn during spunlace. This facilitates sufficient displacement and penetration between the pulp fibers and the cotton yarn, thereby resulting in a smaller two-sided difference in the obtained wet-laid spunlace nonwoven fabric.
[0028] For natural cellulose fiber pulp, due to the presence of numerous fine fibers, fiber loss is a common problem during hydroentangling. To address this property of natural cellulose fiber pulp, this invention employs a hydroentangling support screen with an aperture of 100-110 mesh. The small aperture of the hydroentangling support screen reduces the loss rate of pulp fibers, thereby increasing product yield and reducing production costs. If the aperture is too large, pulp fibers easily escape through the gaps in the support screen under hydraulic action, resulting in significant processing losses. However, smaller apertures are not always better. When the aperture is too small, on the one hand, hydroentangling dehydration is insufficient, leading to uneven dehydration; on the other hand, the pulp fibers are hindered from penetrating and accumulate on the surface, resulting in significant differences between the two sides of the nonwoven fabric.
[0029] Preferably, in step (5), the drying process is as follows: after the spunlace composite fabric is initially dehydrated, it is simultaneously dried and calendered.
[0030] For natural cellulose fiber pulp, the presence of fine fibers, as well as irregular surfaces, cracks, and fuzz on the fiber surface, easily results in a rough surface of the wet-laid spunlace nonwoven fabric. Therefore, this invention employs a special drying and calendering process, performing drying and calendering simultaneously, which improves the surface smoothness and gloss of the wet-laid spunlace nonwoven fabric.
[0031] Preferably, in step (3), before the wet-laid fiber web is stacked with the cotton yarn, photoelectric centering and correction technology is used to unwind the cotton yarn; during the unwinding, stacking and pre-hydroentanglement process, the change in the moving speed of the cotton yarn is controlled to be less than 0.5%.
[0032] The inventors have observed that cotton yarn is prone to weft tilting during unwinding, resulting in irregular mesh patterns in the produced wet-laid spunlace nonwoven fabric. To address this technical problem, this invention employs photoelectric alignment and correction technology during the unwinding process, which prevents weft tilting of the cotton yarn. Simultaneously, by controlling the variation in the cotton yarn's movement speed within 0.5% during unwinding, lamination, and pre-spunlacement, excessive tension can be prevented from disrupting the regularity of the warp and weft mesh of the cotton yarn.
[0033] Preferably, in step (2), the fiber suspension is diluted and purified before wet web forming.
[0034] Compared with the prior art, the present invention has the following advantages:
[0035] (1) The composite of natural cellulose fiber pulp and cotton yarn can utilize the irregular uneven surface of the pulp to improve the composite strength between the wet fiber layer and the cotton yarn.
[0036] (2) The use of a decreasing front hydroentanglement pressure can reduce the difference between the two sides of the wet hydroentangled nonwoven fabric and reduce the loss of pulp fibers.
[0037] (3) The use of spunlace support curtains woven from coarse denier polyester filaments enables sufficient displacement and interweaving between pulp fibers and cotton yarn, thereby reducing the two-sided difference of wet spunlace nonwoven fabric. Attached Figure Description
[0038] Figure 1 This is a top view schematic diagram of a wet-laid hydroentangled nonwoven fabric according to the present invention;
[0039] Figure 2 This is a schematic cross-sectional structure diagram of a wet-laid hydroentangled nonwoven fabric according to the present invention.
[0040] Figure 3 This is an electron microscope image of the nonwoven fabric prepared in Example 1;
[0041] Figure 4This is an electron microscope image of the nonwoven fabric prepared in Example 2;
[0042] Figure 5 The image shows an electron microscope image of the nonwoven fabric prepared in Comparative Example 1.
[0043] The attached diagram is labeled as follows: cotton gauze 1, wet-laid fiber layer 2. Detailed Implementation
[0044] The present invention will be further described below with reference to embodiments.
[0045] General Implementation Examples
[0046] A wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp includes intertwined cotton yarn and a wet-laid fiber layer; the wet-laid fiber layer is formed by wet-laid web formation of natural cellulose fiber pulp; the natural cellulose fiber pulp includes one or more of wood pulp, cotton pulp, hemp pulp and bamboo pulp.
[0047] The above-mentioned wet-spunlace nonwoven fabric was prepared by the following steps:
[0048] (1) After adjusting the solid content in the natural cellulose fiber pulp to 4-7 wt%, the fiber surface is cracked and fuzzy by intermittent disintegration method. The disintegration time is 1-2 min each time, and the disintegration is carried out once every 50-90 s. The disintegration is carried out 3-5 times to obtain a fiber suspension with a disintegration degree of 10-20°SR.
[0049] (2) The fiber suspension is wet-laid to obtain a wet-laid fiber web;
[0050] (3) After unwinding the cotton yarn using photoelectric centering and correction technology, the wet fiber web is stacked with the cotton yarn and pre-hydroentangled. During the unwinding, stacking and pre-hydroentanglement process, the change in the moving speed of the cotton yarn is controlled to be less than 0.5% to obtain a pre-entangled composite fabric.
[0051] (4) The pre-punched composite fabric is introduced onto a hydroentangled support screen made of coarse denier polyester filaments with a diameter of 0.18-0.22 mm and an aperture of 100-110 mesh. The front hydroentanglement is carried out in 4-6 passes with decreasing pressure in the range of 25-55 bar. The hydroentanglement pressure of the first front hydroentanglement is 40-55 bar. Then, the back hydroentanglement is carried out in 0-2 passes with a pressure of 30-60 bar to obtain the hydroentangled composite fabric.
[0052] (5) After the spunlace composite fabric is initially dehydrated, it is simultaneously dried and calendered to obtain a wet spunlace nonwoven fabric composed of cotton yarn and pulp.
[0053] Example 1
[0054] A wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, such as Figure 1 As shown, it includes intertwined cotton yarn 1 and wet-laid fiber layer 2; the wet-laid fiber layer is formed by wet-laid cotton pulp.
[0055] The above-mentioned wet-spunlace nonwoven fabric was prepared by the following steps:
[0056] (1) After adjusting the solid content in the cotton pulp to 4wt%, it is sent to the crushing equipment for intermittent crushing. The crushing time is 1min each time, and the crushing is performed once every 50s. The crushing is performed 5 times to obtain a fiber suspension with a knocking degree of 12°SR.
[0057] (2) After diluting and purifying the fiber suspension, it is sent into the inclined wire mesh forming machine by a slurry pump to form a wet wire mesh and obtain a wet fiber mesh.
[0058] (3) The cotton yarn is fed into the unwinding machine for unwinding. During the unwinding process, a photoelectric centering and correction device is used to prevent the cotton yarn from running off-center. The unwound cotton yarn is fed into the composite conveyor curtain, and the wet fiber web and cotton yarn are overlapped and pre-hydro-spun by the pre-spun head between the inclined web forming device and the composite conveyor curtain. During the unwinding, overlapping and pre-hydro-spun process, the movement speed of the cotton yarn is controlled to change by less than 0.5% to obtain the pre-spun composite fabric.
[0059] (4) The pre-spun composite fabric is introduced onto a spunlace support screen woven from 0.18mm coarse denier polyester yarn with a mesh size of 110 mesh. The front side is spun with four spunlace pressures of 40 bar, 35 bar, 30 bar and 25 bar respectively using a flat spunlace head. Then it is introduced onto a spunlace drum and the back side is spun with one spunlace pressure of 30 bar using a drum spunlace head to obtain the spunlace composite fabric. (5) The spunlace composite fabric is initially dehydrated to a moisture content of 74-76% by vacuum suction. Then it is dried and calendered to obtain a wet spunlace nonwoven fabric composed of cotton yarn and cotton pulp.
[0060] Example 2
[0061] A wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, such as Figure 1 As shown, it includes intertwined cotton yarn 1 and wet-laid fiber layer 2; the wet-laid fiber layer is formed from wood pulp through wet web forming.
[0062] The above-mentioned wet-spunlace nonwoven fabric was prepared by the following steps:
[0063] (1) After adjusting the solid content in the wood pulp to 5wt%, it is sent to the crushing equipment for intermittent crushing. The crushing time is 1.5min each time, and the crushing is performed once every 60s. The crushing is performed 4 times to obtain a fiber suspension with a knockout degree of 14°SR.
[0064] (2) After diluting and purifying the fiber suspension, it is sent into the inclined wire mesh forming machine by a slurry pump to form a wet wire mesh and obtain a wet fiber mesh.
[0065] (3) The cotton yarn is fed into the unwinding machine for unwinding. During the unwinding process, a photoelectric centering and correction device is used to prevent the cotton yarn from running off-center. The unwound cotton yarn is fed into the composite conveyor curtain, and the wet fiber web and cotton yarn are overlapped and pre-hydro-spun by the pre-spun head between the inclined web forming device and the composite conveyor curtain. During the unwinding, overlapping and pre-hydro-spun process, the movement speed of the cotton yarn is controlled to change by less than 0.5% to obtain the pre-spun composite fabric.
[0066] (4) The pre-punched composite fabric is introduced onto a hydroentangled support screen woven from coarse denier polyester filaments with a diameter of 0.20 mm and an aperture of 110 mesh. Five hydroentanglements are performed on the front side using a flat hydroentangled head with hydroentangle pressures of 50 bar, 45 bar, 40 bar, 30 bar and 25 bar respectively. Then, two reverse hydroentanglements are performed using a round drum hydroentangled head with a hydroentangle pressure of 40 bar each to obtain the hydroentangled composite fabric.
[0067] (5) After the spunlace composite fabric is initially dehydrated to a moisture content of 60-62% by a spunlace roller, it is simultaneously dried and calendered to obtain a wet spunlace nonwoven fabric composed of cotton yarn and wood pulp.
[0068] Example 3
[0069] A wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, such as Figure 1 As shown, it includes intertwined cotton yarn 1 and wet-laid fiber layer 2; the wet-laid fiber layer is formed from hemp pulp through wet web forming.
[0070] The above-mentioned wet-spunlace nonwoven fabric was prepared by the following steps:
[0071] (1) After adjusting the solid content of the hemp pulp to 7wt%, it was sent to the crushing equipment for intermittent crushing. The crushing time was 2min each time, and the crushing was carried out once every 90s. The crushing was carried out 5 times to obtain a fiber suspension with a knocking degree of 18°SR.
[0072] (2) After diluting and purifying the fiber suspension, it is sent into the inclined wire mesh forming machine by a slurry pump to form a wet wire mesh and obtain a wet fiber mesh.
[0073] (3) The cotton yarn is fed into the unwinding machine for unwinding. During the unwinding process, a photoelectric centering and correction device is used to prevent the cotton yarn from running off-center. The unwound cotton yarn is fed into the composite conveyor curtain, and the wet fiber web and cotton yarn are overlapped and pre-hydro-spun by the pre-spun head between the inclined web forming device and the composite conveyor curtain. During the unwinding, overlapping and pre-hydro-spun process, the movement speed of the cotton yarn is controlled to change by less than 0.5% to obtain the pre-spun composite fabric.
[0074] (4) The pre-punched composite fabric is introduced onto a hydroentangled support screen woven from coarse denier polyester filaments with a diameter of 0.22 mm and a mesh size of 100 mesh. The front hydroentangled fabric is subjected to six hydroentangled passes with pressures of 55 bar, 50 bar, 46 bar, 42 bar, 35 bar and 30 bar respectively using a flat hydroentangled head. Then, the reverse hydroentangled fabric is subjected to two hydroentangled passes with pressures of 50 bar and 60 bar respectively using a round drum hydroentangled head to obtain the hydroentangled composite fabric.
[0075] (5) After the spunlace composite fabric is initially dehydrated to a moisture content of 61-64% by a spunlace roller, it is simultaneously dried and calendered to obtain a wet spunlace nonwoven fabric composed of cotton yarn and hemp pulp.
[0076] Example 4
[0077] The only difference between this embodiment and embodiment 1 is that in step (4), the hydroentangling pressure of the first front hydroentangling is 35 bar, while the other raw materials and preparation process are the same as in embodiment 1.
[0078] Example 5
[0079] The only difference between this embodiment and embodiment 3 is that in step (4), the hydroentangling pressure of the first front hydroentangling is 60 bar, while the other raw materials and preparation process are the same as in embodiment 3.
[0080] Example 6
[0081] The only difference between this embodiment and embodiment 2 is that in step (4), the hydroentangling pressures of the 2nd to 5th front hydroentangling passes are 40 bar, 35 bar, 25 bar, and 20 bar, respectively. The other raw materials and preparation processes are the same as in embodiment 2.
[0082] Example 7
[0083] The only difference between this embodiment and embodiment 1 is that in step (4), the front hydroentanglement is made of coarse denier polyester yarn with a diameter of 0.10 mm. The other raw materials and preparation process are the same as in embodiment 1.
[0084] Example 8
[0085] The only difference between this embodiment and embodiment 2 is that in step (4), a 120-mesh spunlace support screen is used when spunlace the front side. The other raw materials and preparation process are the same as in embodiment 2.
[0086] Example 9
[0087] The only difference between this embodiment and embodiment 3 is that in step (4), a 90-mesh spunlace support screen is used when spunlace the front side. The other raw materials and preparation process are the same as in embodiment 3.
[0088] Comparative Example 1
[0089] The only difference between Comparative Example 1 and Example 2 is that in step (1), the cotton pulp is replaced with a pulp made of lyocell fiber and water. All other raw materials and preparation processes are the same as in Example 2.
[0090] Comparative Example 2
[0091] The only difference between this comparative example and Example 1 is that in step (4), the hydroentangling pressures of the first to fourth front hydroentangling passes are 25 bar, 30 bar, 35 bar, and 40 bar, respectively. The other raw materials and preparation processes are the same as in Example 1.
[0092] Comparative Example 3
[0093] The only difference between this comparative example and Example 1 is that in step (4), the hydroentangling pressure of the four front hydroentangling passes is 40 bar, while the other raw materials and preparation process are the same as in Example 1.
[0094] Comparative Example 4
[0095] The only difference between this comparative example and Example 1 is that in step (4), the hydroentangling pressure of the four front hydroentangling passes is 30 bar, while the other raw materials and preparation process are the same as in Example 1.
[0096] Test Example 1: Fiber Performance Test
[0097] The nonwoven fabrics prepared in Examples 1, 2, and 1 (Comparative Example 1) were observed under an electron microscope, and the results are shown in the figures below. Figures 3-5 As can be seen from the figure, after being broken down and compounded with cotton yarn to make nonwoven fabric, the surface of wood pulp fibers has a large number of irregular bumps and depressions, while the surface of lyocell fibers is smooth.
[0098] Test Example 2: Nonwoven Fabric Performance Test
[0099] The performance of the wet-laid spunlace nonwoven fabrics prepared in Examples 1-9 and Comparative Examples 1-4 was tested, and the results are shown in Table 1.
[0100] Table 1
[0101]
[0102] 1 Two-sided roughness difference: The absolute value of the difference in surface roughness (SMD) between two surfaces.
[0103] Analyzing the data in Table 1, we can draw the following conclusions:
[0104] (1) Compared with Comparative Example 1, the nonwoven fabrics obtained in Examples 1-3 showed significantly higher tensile strength (longitudinal and transverse) and peel strength. This indicates that, compared with regenerated cellulose fibers, using natural cellulose pulp in conjunction with the process of this application can improve the composite strength between the wet-laid fiber layer and the cotton yarn. The reason is that: the surface of regenerated cellulose fibers is smooth, and because the surface is already shaped, it is difficult to form a large number of cracks and fluff on its surface even when it is broken down, thus the composite strength between it and the cotton yarn is low; while the surface of pulp fibers has irregular uneven surfaces such as scales, horizontal and vertical lines, and spiral lines, and it is easy to generate fluff and cracks when broken down. These structures can generate greater friction between the wet-laid fiber layer and the cotton yarn, thereby improving the composite strength between the two.
[0105] (2) Compared with Comparative Examples 2 and 4, the nonwoven fabric obtained in Example 1 has a significantly smaller difference in roughness between the two sides; compared with Comparative Example 3, the nonwoven fabric obtained in Example 1 has a larger basis weight. This indicates that compared with the hydroentangling method using increasing or constant hydroentangling pressure on the front side, setting decreasing hydroentangling pressure is beneficial to reducing the difference between the two sides of the nonwoven fabric and reducing pulp fiber loss. The reason is as follows: In pre-punched composite fabrics, the pulp fibers are not yet entangled and are in a loose state. At this time, a larger hydroentangling pressure can allow the pulp fibers to penetrate the cotton yarn and form displacement and interweaving. Then, a smaller hydroentangling pressure is used to make the pulp fibers entangle with each other. If a constant hydroentangling pressure is used for front-side hydroentangling, it will be difficult for the pulp fibers and cotton yarn to form sufficient displacement and interweaving, resulting in a large difference between the two sides of the nonwoven fabric, or a large loss of pulp fibers due to the presence of many fine fibers in the pulp. If the hydroentangling pressure is set to increase progressively, after the pulp fibers form entanglement under a smaller hydroentangling pressure, the entangled pulp fibers are not easy to penetrate the cotton yarn under a subsequent larger hydroentangling pressure, thus causing a large difference between the two sides of the nonwoven fabric.
[0106] (3) Compared with Example 4, the nonwoven fabric obtained in Example 1 has a smaller difference between the two sides; compared with Example 5, the nonwoven fabric obtained in Example 3 has a larger basis weight. This indicates that during the hydroentangling process on the front side, if the pressure of the first hydroentangling is too low, the difference between the two sides of the nonwoven fabric will be large, while if the pressure is too high, more pulp fibers will be lost.
[0107] (4) Compared with Example 6, the nonwoven fabric obtained in Example 2 has significantly higher breaking strength (longitudinal and transverse). This indicates that if the subsequent hydroentangling pressure is too low during the front hydroentangling process, it will affect the strength of the nonwoven fabric. The reason is that if the subsequent front hydroentangling pressure is too low, it will be difficult for the pulp fibers to fully entangle, resulting in lower strength of the wet hydroentangled nonwoven fabric.
[0108] (4) Compared to Example 7, the nonwoven fabric obtained in Example 1 has a smaller two-sided difference. This indicates that using a spunlace support curtain woven from coarse denier polyester filaments for front-side hydroentangling is beneficial in reducing the two-sided difference of the nonwoven fabric. The reason is that the spunlace support curtain woven from coarse denier polyester filaments has a larger height difference space in the cross-sectional direction, which can provide more space for the pulp fibers to displace and penetrate into the pores of the cotton yarn during hydroentangling, which is conducive to the formation of sufficient displacement and penetration between the pulp fibers and the cotton yarn, thereby resulting in a smaller two-sided difference in the obtained wet-spunlace nonwoven fabric.
[0109] (5) Compared to Example 8, the nonwoven fabric obtained in Example 2 has a larger basis weight; compared to Example 9, the nonwoven fabric obtained in Example 3 has a smaller difference between the two sides. This indicates that during the hydroentangling process on the front side, if the aperture of the hydroentangling support curtain is too large, excessive pulp fiber loss will occur; if the aperture is too small, a larger difference between the two sides of the nonwoven fabric will occur. The reason is that when the aperture of the hydroentangling support curtain is too large, more pulp fiber will be lost due to the presence of more fine fibers in the pulp; when the aperture of the hydroentangling support curtain is too small, the pulp fiber penetration will be obstructed and it will accumulate on the surface, resulting in a larger difference between the two sides of the nonwoven fabric.
[0110] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.
[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A method for preparing a wet-process spunlace nonwoven fabric composed of cotton yarn and pulp, characterized in that, include: S1. Natural cellulose fiber pulp is broken down to create cracks and fuzz on the fiber surface, resulting in a fiber suspension; S2. The fiber suspension is wet-laid to obtain a wet-laid fiber web; S3. The wet-laid fiber web and cotton yarn are stacked and pre-hydroentangled to obtain a pre-entangled composite fabric; S4. Perform 4 to 6 passes of hydroentangling with decreasing pressure on the front side of the pre-spun composite fabric, and then perform 0 to 2 passes of hydroentangling on the reverse side to obtain a hydroentangled composite fabric. Dry the fabric to obtain a wet-laid hydroentangled nonwoven fabric composed of cotton yarn and pulp, which includes intertwined cotton yarn and wet-laid fiber layer. The wet-laid fiber layer is formed by wet-laid web formation of natural cellulose fiber pulp.
2. The preparation method according to claim 1, characterized in that, The natural cellulose fiber pulp includes one or more of wood pulp, cotton pulp, hemp pulp, and bamboo pulp.
3. The preparation method according to claim 1, characterized in that, In step S1, the degree of percussion of the fiber suspension is 10~20°SR.
4. The preparation method according to claim 1, characterized in that, In step S1, before crushing, the solid content in the natural cellulose fiber pulp is adjusted to 4-7 wt%; the crushing adopts an intermittent crushing method, the crushing time is 1-2 minutes each time, crushing once every 50-90 seconds, and the number of crushing times is 3-5 times.
5. The preparation method according to claim 1, characterized in that, In step S4, the hydroentangling pressure of the front hydroentangling is 25~55 bar, wherein the hydroentangling pressure of the first front hydroentangling is 40~55 bar.
6. The preparation method according to claim 1 or 5, characterized in that, In step S4, the hydroentangling pressure on the reverse side is 30~60 bar.
7. The preparation method according to claim 1, characterized in that, In step S4, the front hydroentangling process is carried out on a hydroentangling support screen with an aperture of 100~110 mesh; the hydroentangling support screen is woven from coarse denier polyester yarn with a diameter of 0.18~0.22mm.
8. The preparation method according to claim 1, characterized in that, In step S4, the specific drying process is as follows: after the spunlace composite fabric is initially dehydrated, it is simultaneously dried and calendered.
9. The preparation method according to claim 1, characterized in that, In step S3, before the wet-laid fiber web is stacked with the cotton yarn, photoelectric centering and correction technology is used to unwind the cotton yarn; during the unwinding, stacking and pre-hydroentanglement process, the change in the moving speed of the cotton yarn is controlled to be less than 0.5%.
10. A wet-laid spunlace nonwoven fabric composed of cotton yarn and pulp, prepared by the preparation method according to any one of claims 1 to 9.