Water-disintegrable spunlace nonwoven fabric and manufacturing method thereof

Abstract

To provide a water-disintegrable spunlace nonwoven fabric, which can be quickly disintegrated in water and has high wet strength, and also to provide a manufacturing method thereof.SOLUTION: A water-disintegrable spunlace nonwoven fabric is manufactured by wet molding and spunlace processing and includes 60% to 85% in mass fraction of natural fibers and 15% to 40% of regenerated cellulosic fibers longer than the natural fiber. The water-disintegrable spunlace has basis weight of 35 gsm to 55 gsm and thickness of 0.3 mm to 0.5 mm. Water disintegration time is less than 100 s. Wet strength in an MD direction is 3.0 N to 5.0 N. Wet strength in a CD direction is 2.0 N to 3.5 N.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of spunlaced nonwoven products and production processes, and more particularly to a water-disintegrable spunlaced nonwoven fabric and a method for producing the same. [Background technology]

[0002] Water-decomposable nonwoven fabrics break down when they come into contact with water and do not clog toilets or sewer systems. Currently, water-disintegrable nonwoven fabrics are made by forming a fiber web using natural fibers, regenerated cellulose fibers, etc. through a web-forming process, and then the most important step of reinforcing the fiber web is required so that the water-disintegrable nonwoven fabric product has good wet usability while retaining its water-disintegrability. Currently, there are three main methods for reinforcing water-disintegrable nonwoven fabrics: chemical bonding, thermal bonding, and spunlace.

[0003] The key to reinforcing water-disintegrable nonwoven fabrics using chemical bonding is the use of a special adhesive that dissolves when sheared and washed with water, turning the fibers into a water-disintegrable state. The type of adhesive used in this method plays a crucial role in the product's water-disintegrability, and the safety and irritation of the chemical reagents are also important considerations. Water-disintegrable nonwoven fabrics using thermal bonding are produced by mixing a small amount of heat-fusible fiber with cellulose fiber to form a fibrous web, and then melting the heat-fusible fiber using heating methods such as a heat press or hot air to bond and reinforce the cellulose fiber. Common heat-fusible fibers include ES fiber, polylactic acid fiber (PLA), polyethylene fiber, and polypropylene fiber. However, heat-fusible fibers are usually not 100% biodegradable, and using large amounts of them can result in non-degradable fibers accumulating in wastewater treatment systems, increasing the burden on wastewater treatment. Therefore, the spunlace method, which is more environmentally friendly, is widely used. However, nonwoven fabrics produced by the prior art spunlace process either have low wet strength and tend to break down during use, or have too high wet strength and take a long time to disintegrate, causing toilet or sewer blockages. Therefore, there is an urgent need to provide a water-disintegratable spunlace nonwoven fabric that has a short water disintegration time and high wet strength, and a method for producing the same. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, the present invention provides a water-decomposable spunlace nonwoven fabric that can be quickly decomposed in water and has high wet strength, and a method for producing the same. [Means for solving the problem]

[0005] The present invention discloses a water-disintegratable spunlace nonwoven fabric comprising, by mass, 60% to 85% natural fibers and 15% to 40% regenerated cellulose fibers longer than the natural fibers, with a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a water disintegration time of less than 100 seconds, a wet strength in the MD direction of 3.0 N to 5.0 N, and a wet strength in the CD direction of 2.0 N to 3.5 N.

[0006] The present invention also provides a method for producing the water-decomposable spunlace nonwoven fabric, the method comprising the steps of: preparing natural fibers and regenerated cellulose fibers in a predetermined mass fraction; pre-treating the natural fibers and regenerated cellulose fibers; sufficiently mixing the pre-treated natural fibers and regenerated cellulose fibers with water to prepare a slurry having a concentration of 3% by mass to 6% by mass; gradually diluting and mixing the natural fibers and regenerated cellulose fibers to obtain a micro-turbulent slurry having a concentration of 0.02% by mass to 0.05% by mass; and supplying the micro-turbulent slurry to a forming head. The micro-turbulent slurry is directly sprayed from the forming head onto a forming net of a web forming machine to form a uniform fiber web, and the forming net is then sprayed. The present invention discloses a method for producing a water-decomposable spunlace nonwoven fabric, which includes a web-forming process using a wet method in which a fiber web is dehydrated using a dehydration device located below the nonwoven fabric and the humidity is controlled using a humidity sensor; a hydroentangling process in which the dehydrated fiber web is transported to a hydroentangling device and the fiber web is hydroentangled using 3 to 7 water jet heads with relatively low-pressure water jets at a water jet pressure of 10 bar to 50 bar while the fiber web is dehydrated using 3 to 4 stages of negative pressure suction to obtain a molded nonwoven fabric; a light pressing process in which the molded nonwoven fabric is lightly pressed at a pressure of 0.1 MPa to 0.15 MPa; and a drying process in which the lightly pressed molded nonwoven fabric is dried by infrared drying or hot air penetration oven drying. [Effects of the Invention]

[0007] The water-decomposable spunlace nonwoven fabric and its manufacturing method provided by the present invention have at least the following beneficial effects compared to the prior art.

[0008] In the present invention, by combining natural fibers and regenerated cellulose fibers of different finenesses and lengths, the fibers are entangled in a spatial structure, forming a dense fiber layer structure, and the fiber orientation results in a higher tensile strength in the machine direction than in the direction perpendicular to the machine direction. Hydroentanglement is achieved by using a web support net to transport the fiber web under conditions of relatively low water jet pressure, multiple water jet heads, and small water jet nozzle spacing, thereby forming regular pores on the surface of the nonwoven fabric. These pores allow the water-disintegratable spunlace nonwoven fabric to be hydrolyzed more quickly under water flow conditions. Dehydrating the fibers using negative pressure suction transforms the nonwoven fabric from a saturated bulky state to a dense state. This increases fiber-to-fiber contact, increases the bonding area between fibers, and improves the hydrogen bonding ability of the fibers. Therefore, the water-disintegratable spunlace nonwoven fabric of the present invention has a water-disintegration time of less than 100 seconds, a wet strength in the MD direction of 3.0 N to 5.0 N, and a wet strength in the CD direction of 2.0 N to 3.5 N, and is quickly disintegratable in water and has high wet strength.

[0009] Of course, any product embodying the present invention does not necessarily have to achieve all of the above technical effects at the same time. Other features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, taken in conjunction with the drawings. [Brief explanation of the drawings]

[0010] The drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the mechanisms of the invention. [Figure 1] 1 is a schematic plan view of a water-disintegratable spunlace nonwoven fabric of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of FIG. [Figure 3] FIG. 2 is another enlarged partial view of FIG. [Figure 4] 1 is a flowchart of a method for producing a water-decomposable spunlaced nonwoven fabric provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Various exemplary embodiments of the present invention will be described in detail below with reference to the drawings. Note that the relative arrangement of components and steps, formulas and numerical values ​​described in these embodiments do not limit the scope of the present invention unless otherwise specified. The following description of at least one exemplary embodiment is intended to be merely illustrative and is not intended to limit the invention, its application, or uses.

[0012] Techniques, methods and devices that are known to those skilled in the art may not be discussed in detail, but where appropriate, these techniques, methods and devices should be considered part of the description. Any specific values ​​in all examples shown and described herein should be construed as merely illustrative and not limiting, and therefore, in other examples of exemplary implementations, the values ​​may vary.

[0013] It should be noted that in the following figures, like reference numbers and letters represent like items, so once an item is defined in one figure, there is no need to further describe it in subsequent figures. Reference is made to Figures 1, 2, and 3. Figure 1 is a schematic plan view of a water-disintegratable spunlace nonwoven fabric of the present invention, Figure 2 is a partially enlarged view of Figure 1, and Figure 3 is another partially enlarged view of Figure 1. Figures 2 and 3 are enlarged at different magnifications. The present invention provides a water-disintegratable spunlace nonwoven fabric comprising, by mass fraction, 60% to 85% natural fibers and 15% to 40% regenerated cellulose fibers having a length longer than that of the natural fibers, with a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a water disintegration time of less than 100 seconds, a wet strength in the MD direction of 3.0 N to 5.0 N, and a wet strength in the CD direction of 2.0 N to 3.5 N.

[0014] In this invention, the wet strength is measured in accordance with "GB / T24218.3 Test Methods for Nonwoven Fabrics, Part 3: Determination of Breaking Strength and Breaking Elongation (Strip Method)." Specifically, five or more specimens are cut out of a water-decomposable spunlace nonwoven fabric sample in the machine direction (machine direction) and the cross direction (nonwoven fabric width direction) so that the longitudinal direction of the specimen is parallel to the machine direction (machine direction) and the cross direction (nonwoven fabric width direction), respectively. The specimen width is 50±0.5 mm, and the length satisfies the nominal chuck distance of 200 mm. The strength in the MD direction is the breaking strength in the machine direction, and the strength in the CD direction is the breaking strength in the cross direction. The water disintegration time (ease of disintegration) is measured in accordance with JIS P 4501. The basis weight is measured in accordance with GB / T24218.1. The thickness is measured in accordance with GB / T24218.2.

[0015] Example 1 The water-disintegratable spunlace nonwoven fabric of this example was produced by a wet-molding and spunlace process, and contained 70% natural fibers and 30% regenerated cellulose fibers, which were longer than the natural fibers, by mass fraction, with a basis weight of 35 gsm, a thickness of 0.3 mm, and a water disintegration time of less than 100 seconds. Specific parameter data are shown in Table 1 below.

[0016] [Table 1]

[0017] Example 2 The water-disintegratable spunlace nonwoven fabric of this example was produced by a wet-molding and spunlace process, and contained 70% natural fibers and 30% regenerated cellulose fibers, which were longer than the natural fibers, by mass fraction, with a basis weight of 40 gsm, a thickness of 0.4 mm, and a water disintegration time of less than 100 seconds. Specific parameter data are shown in Table 2 below.

[0018] [Table 2]

[0019] Example 3 The water-disintegratable spunlace nonwoven fabric of this example was produced by a wet-molding and spunlace process, and contained 75% natural fibers and 25% regenerated cellulose fibers, which were longer than the natural fibers, with a basis weight of 45 gsm, a thickness of 0.42 mm, and a water disintegration time of less than 100 seconds. Specific parameter data are shown in Table 3 below.

[0020] [Table 3]

[0021] Example 4 The water-disintegratable spunlace nonwoven fabric of this example was produced by a wet-molding and spunlace process, and contained 80% natural fibers and 20% regenerated cellulose fibers, which were longer than the natural fibers, with a basis weight of 50 gsm, a thickness of 0.43 mm, and a water disintegration time of less than 100 seconds. Specific parameter data are shown in Table 4 below.

[0022] [Table 4]

[0023] Example 5 The water-disintegratable spunlace nonwoven fabric of this example was produced by a wet-molding and spunlace process, and contained 85% natural fibers and 15% regenerated cellulose fibers, which were longer than the natural fibers, with a basis weight of 55 gsm, a thickness of 0.43 mm, and a water disintegration time of less than 100 seconds. Specific parameter data are shown in Table 5 below.

[0024] [Table 5]

[0025] In some preferred embodiments, the natural fibers include a first type of natural fiber and a second type of natural fiber, the first type of natural fiber having a higher beating degree than the second type of natural fiber, and the regenerated cellulose fibers include a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber, the surfaces of the first type of regenerated cellulose fiber are not deformed, and the surfaces of the second type of regenerated cellulose fiber have pits.

[0026] The natural fibers are divided into two parts, a first type of natural fiber and a second type of natural fiber, and the first type of natural fiber and the second type of natural fiber are separately beaten so that the beating degree of the first type of natural fiber is greater than that of the second type of natural fiber. Preferably, the beating degree of the first type of natural fiber is 35°SR to 41°SR, for example, 35°SR, 36°SR, 37°SR, 38°SR, 39°SR, 40°SR, or 41°SR, and the beating degree of the second type of natural fiber is 16°SR to 30°SR, for example, 16°SR, 18°SR, 19°SR, 20°SR, 21°SR, 22°SR, 23°SR, 24°SR, 25°SR, 26°SR, 27°SR, 28°SR, 29°SR, or 30°SR. Here, the mass percentages of the first type of natural fiber and the second type of natural fiber are not equal. The mass percentage of the first type of natural fiber may be lower than the mass percentage of the second type of natural fiber. By making the beating degree of the first type of natural fiber higher than that of the second type of natural fiber, the wet strength of the water-decomposable spunlace nonwoven fabric can be increased.

[0027] Regenerated cellulose fibers are divided into two types: first-type regenerated cellulose fibers and second-type regenerated cellulose fibers. The first-type regenerated cellulose fibers have a non-deformable surface, while the second-type regenerated cellulose fibers have pits on their surfaces. The pits improve the bonding between the second-type regenerated cellulose fibers and natural fibers, thereby increasing the wet strength of the water-degradable spunlace nonwoven fabric.

[0028] The natural fibers used in Examples 1 to 5 above are the first and second types of natural fibers of this embodiment. The regenerated cellulose fibers used in Examples 1 to 5 above are the first and second types of regenerated cellulose fibers of this embodiment. In some preferred embodiments, the mass ratio of the first type of natural fiber to the second type of natural fiber is 1:9 to 3:7, the first type of natural fiber and the second type of natural fiber are made of the same material, and both contain hardwood pulp and softwood pulp, and when the mass of the natural fibers is 100%, the mass fraction of the hardwood pulp is 25% to 50%, and the mass fraction of the softwood pulp is 50% to 75%.

[0029] The length of natural fibers is 1 mm to 3 mm. For example, the length of softwood pulp fibers is 2 mm to 3 mm, and the length of hardwood pulp fibers is about 1 mm. Natural fibers generally include hardwood pulp and softwood pulp. The fiber length of hardwood pulp and softwood pulp is usually shorter than that of regenerated cellulose fibers, which allows the water-decomposable spunlaced nonwoven fabric to have high wet strength. Optionally, the mass fraction of hardwood pulp is 25% and the mass fraction of softwood pulp is 75%; optionally, the mass fraction of hardwood pulp is 30% and the mass fraction of softwood pulp is 70%; optionally, the mass fraction of hardwood pulp is 35% and the mass fraction of softwood pulp is 65%; optionally, the mass fraction of hardwood pulp is 45% and the mass fraction of softwood pulp is 55%; optionally, the mass fraction of hardwood pulp is 50% and the mass fraction of softwood pulp is 50%.

[0030] Optionally, the mass ratio of the first type of natural fiber to the second type of natural fiber may be 1:9, 2:8, 3:7, or of course any mass ratio between 1:9 and 3:7, and is not particularly limited. The first and second natural fibers are made of the same material, containing hardwood pulp and softwood pulp. However, the first and second natural fibers have different degrees of beating, with the first natural fiber having a higher degree of beating than the second natural fiber. This increases the wet strength of the water-disintegrable spunlace nonwoven fabric. However, the mass percentage of the first natural fiber should not be too high. If the mass percentage of the first natural fiber is too high, the wet strength will be too high and the water disintegration time will be too long. In this embodiment, the mass ratio of the first natural fiber to the second natural fiber is set to 1:9 to 3:7 to ensure a water disintegration time of less than 100 seconds. This allows the water-disintegrable spunlace nonwoven fabric to have high wet strength and a water disintegration time of less than 100 seconds.

[0031] In some preferred embodiments, the mass ratio of the first type of regenerated cellulose fibers to the second type of regenerated cellulose fibers is 7:3 to 9:1, the first type of regenerated cellulose fibers and the second type of regenerated cellulose fibers are made of the same material and both contain one or two types selected from lyocell fibers and viscose fibers, the lyocell fibers have a fineness of 0.9D to 1.5D and a length of 3mm to 10mm, and the viscose fibers have a fineness of 0.5D to 2.0D and a length of 3mm to 10mm.

[0032] Optionally, the fineness of the lyocell fiber may be 0.9D, 1.0D, 1.1D, 1.2D, 1.3D, 1.4D, 1.5D, or any value between 0.9D and 1.5D, and the length may be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any value between 3mm and 10mm. The fineness of the viscose fiber may be 0.5D, 0.6D, 0.7D, 0.8D, 0.9D, 1.0D, 1.1D, 1.2D, 1.3D, 1.4D, 1.5D, 1.6D, 1.7D, 1.8D, 1.9D, 2.0D, or any value between 0.5D and 2.0D, and the length may be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any value between 3mm and 10mm. Here, the unit of fiber fineness is denier, abbreviated as D.

[0033] The mass ratio of the first type of regenerated cellulose fiber to the second type of regenerated cellulose fiber may be 9:1, 8:2, or 7:3. The first type of regenerated cellulose fiber and the second type of regenerated cellulose fiber are made of the same material, and both contain one or two types of fiber selected from lyocell fiber and viscose fiber. However, the surface of the first type of regenerated cellulose fiber is not deformed, and the surface of the second type of regenerated cellulose fiber has pits. The pits improve the bond between the second type of regenerated cellulose fiber and natural fibers, thereby increasing the wet strength of the water-disintegrable spunlace nonwoven fabric. However, the mass percentage of the second type of regenerated cellulose fiber should not be too high. If the mass percentage of the second type of regenerated cellulose fiber is too high, the wet strength will be too high and the hydrolysis time will be too long. In this embodiment, the mass ratio of the first type of regenerated cellulose fiber to the second type of regenerated cellulose fiber is set to 7:3 to 9:1 to ensure a hydrolysis time of less than 100 seconds. This results in a water-disintegrable spunlace nonwoven fabric with high wet strength and a hydrolysis time of less than 100 seconds.

[0034] In the above Example 1, when the mass of the water-decomposable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 30%, of which the content of lyocell fiber is 15%, the content of viscose fiber is 15%, the fineness of the lyocell fiber is 1.0D and the length is 6mm, and the fineness of the viscose fiber is 1.0D and the length is 8mm.

[0035] In the above Example 2, when the mass of the water-decomposable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 30%, of which the content of lyocell fiber is 20%, the content of viscose fiber is 10%, the fineness of the lyocell fiber is 1.0D and the length is 6mm, and the fineness of the viscose fiber is 1.0D and the length is 8mm.

[0036] In the above Example 3, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 25%, of which the content of lyocell fiber is 5%, the content of viscose fiber is 20%, the fineness of the lyocell fiber is 1.0D, the length is 6mm, and the fineness of the viscose fiber is 1.5D, the length is 8mm.

[0037] In another embodiment of the present invention, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 15%, of which the content of lyocell fiber is 5%, the content of viscose fiber is 10%, the fineness of the lyocell fiber is 1.0D and the length is 6mm, and the fineness of the viscose fiber is 1.0D and the length is 8mm.

[0038] In another embodiment of the present invention, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 20%, of which the content of lyocell fiber is 15%, the content of viscose fiber is 5%, the fineness of the lyocell fiber is 1.0D and the length is 6mm, and the fineness of the viscose fiber is 1.0D and the length is 8mm.

[0039] That is, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 15% to 40%, of which the content of lyocell fiber is 5% to 20%, the fineness of the lyocell fiber can be 1.0D and the length can be 6mm, and the content of viscose fiber can be 5% to 20%, the fineness of the viscose fiber can be 1.0D or 1.5D and the length can be 8mm.

[0040] In the above Example 4, when the mass of the water-degradable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fiber is 20%, of which the content of lyocell fiber with a fineness of 1.0D and a length of 6mm is 5%, the content of lyocell fiber with a fineness of 1.0D and a length of 8mm is 5%, the content of viscose fiber with a fineness of 1.0D and a length of 8mm is 5%, and the content of viscose fiber with a fineness of 1.5D and a length of 10mm is 5%.

[0041] In the above Example 5, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 15%, of which the content of lyocell fiber with a fineness of 1.0D and a length of 6mm is 5%, the content of lyocell fiber with a fineness of 1.0D and a length of 8mm is 5%, the content of viscose fiber with a fineness of 1.0D and a length of 8mm is 3%, and the content of viscose fiber with a fineness of 1.5D and a length of 10mm is 2%.

[0042] In another embodiment of the present invention, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 30%, of which the content of lyocell fiber with a fineness of 1.0D and a length of 6mm is 10%, the content of lyocell fiber with a fineness of 1.0D and a length of 8mm is 8%, the content of viscose fiber with a fineness of 1.0D and a length of 8mm is 5%, and the content of viscose fiber with a fineness of 1.5D and a length of 10mm is 7%.

[0043] In another embodiment of the present invention, when the mass of the water-degradable spunlace nonwoven fabric is 100%, the mass fraction of regenerated cellulose fiber is 40%, of which the content of lyocell fiber with a fineness of 1.0D and a length of 6mm is 10%, the content of lyocell fiber with a fineness of 1.0D and a length of 8mm is 10%, the content of viscose fiber with a fineness of 1.0D and a length of 8mm is 10%, and the content of viscose fiber with a fineness of 1.5D and a length of 10mm is 10%.

[0044] That is, when the mass of the water-decomposable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fiber is 15% to 40%, of which the content of lyocell fiber with a fineness of 1.0D and a length of 6mm is 5% to 10%, the content of lyocell fiber with a fineness of 1.0D and a length of 8mm is 5% to 10%, the content of viscose fiber with a fineness of 1.0D and a length of 8mm is 3% to 10%, and the content of viscose fiber with a fineness of 1.5D and a length of 10mm is 2% to 10%.

[0045] As described above, by combining lyocell fibers and viscose fibers having different finenesses and lengths, it is possible to increase the strength, improve the water-decomposability, and shorten the water-decomposition time. Still referring to Figure 1, in some preferred embodiments, the water-disintegratable spunlaced nonwoven fabric has a plurality of through-holes aligned in the longitudinal and width directions. The through-holes are formed by the spunlacing process. Here, the longitudinal direction is the direction in which the nonwoven fabric advances (machine direction) during production, and the width direction is the direction perpendicular to the direction in which the nonwoven fabric advances.

[0046] Hydroentanglement uses a web support net to transport the fibrous web under conditions of relatively low water jet pressure, multiple water jet heads, and small water jet nozzle spacing, forming regular pores (i.e., through-holes) on the surface of the nonwoven fabric. These pores (i.e., through-holes) allow the water-disintegratable spunlace nonwoven fabric to be hydrolyzed more quickly under water flow conditions. In some preferred embodiments, the water-decomposable spunlace nonwoven fabric has a first surface and a second surface opposing each other in the thickness direction, and the angle between the through holes and the first surface is an obtuse angle, and the angle between the through holes and the second surface is an acute angle.

[0047] In this embodiment, the through-holes are not vertical holes but oblique holes. The angle between the through-holes and the first surface is an obtuse angle, and the angle between the through-holes and the second surface is an acute angle. Here, the first surface is the front surface of the water-disintegrable spunlace nonwoven fabric, and the second surface is the back surface of the water-disintegrable spunlace nonwoven fabric. The fact that the through-holes are oblique holes is advantageous for the water-disintegration of the water-disintegrable spunlace nonwoven fabric and can shorten the water-disintegration time. It has been confirmed that when the through-holes are oblique holes, the water-disintegration time is shorter by 5 to 8 seconds compared to when the through-holes are vertical holes. The performance parameters of the water-disintegrable spunlace nonwoven fabric when the through-holes are oblique holes are shown in Table 6 below. Preferably, the obtuse angle is equal to or greater than 90° and equal to or less than 115°, and the acute angle is equal to or less than 75° and less than 90°.

[0048] [Table 6]

[0049] In some preferred embodiments, the antibacterial nanoparticles are sprayed onto the surface of the water-decomposable spunlaced nonwoven fabric. Preferably, antibacterial nanoparticles, such as nanomaterials having antibacterial properties, are applied to the surface of the water-decomposable spunlace nonwoven fabric by spraying. These antibacterial nanoparticles have antibacterial properties without affecting water-decomposability. Preferably, the antibacterial component can be an extract of a plant such as aloe vera or honeysuckle. The extract of a plant such as aloe vera or honeysuckle can be prepared into antibacterial nanoparticles, which can then be applied to the surface of a water-decomposable spunlace nonwoven fabric by spraying, thereby achieving antibacterial properties and also being excellent in terms of health.

[0050] Based on the same inventive concept, the present invention further provides a method for producing the above-mentioned water-disintegrable spunlace nonwoven fabric. Please refer to Figure 4. Figure 4 is a flowchart of the method for producing the water-disintegrable spunlace nonwoven fabric provided by the present invention. This method includes the following steps: Raw material preparation step S1: Natural fibers and regenerated cellulose fibers are prepared in a predetermined mass fraction. Pretreatment step S2: The natural fibers and regenerated cellulose fibers are pretreated. Slurry preparation step S3: The pretreated natural fibers and regenerated cellulose fibers are thoroughly mixed with water to prepare a slurry with a concentration of 3% to 6% by mass. Slurry charging step S4: The slurry is gradually diluted and mixed to obtain a micro-turbulent slurry with a concentration of 0.02 mass % to 0.05 mass %, and this micro-turbulent slurry is supplied to the forming head. Wet web formation process S5: Micro-turbulent slurry is sprayed directly from the forming head onto the forming net of the web forming machine to form a uniform fiber web, and the fiber web is dehydrated by a dehydration device located below the forming net, and the humidity is controlled by a humidity sensor. Hydroentangling step S6: The dewatered fiber web is transported to a hydroentangling device, where the fiber web is hydroentangled using 3 to 7 water jet heads with relatively low-pressure water jets at a water jet pressure of 10 bar to 50 bar, while the fiber web is dewatered by 3 to 4 stages of negative pressure suction to obtain a molded nonwoven fabric. Light pressing step S7: The molded nonwoven fabric is lightly pressed at a pressure of 0.1 MPa to 0.15 MPa. Drying step S8: The lightly pressed molded nonwoven fabric is dried by infrared drying or hot air penetration oven drying. Specifically, in the slurry preparation step S3, the concentration of the slurry may be any value between 3% by mass and 6% by mass, such as 3%, 4.0%, 4.5%, 5%, 5.5%, or 6% by mass.

[0051] In the slurry preparation step S4, a stepwise dilution and mixing method is employed, i.e., the slurry is gradually diluted from a high concentration to a low concentration. For example, the slurry concentration may be first diluted to 2% by mass, then from 2% to 1% by mass, then from 1% to 0.1% by mass, and finally from 0.1% to 0.05% by mass. See publication number CN106351053A, entitled "Method for producing a water-disintegrable and biodegradable spunlaced nonwoven fabric using a stepwise mixing method." In this method, a stepwise discharge section is installed to gradually mix the slurry. Specifically, the stepwise discharge section is connected to the outlet of a slurry dispenser (preferably a conical slurry dispenser). The stepwise discharge section includes a first slurry-transporting circular pipe section, a second slurry-transporting circular pipe section, and a third slurry-transporting rectangular pipe section, which are connected in series. The first slurry transport circular pipe section and the second slurry transport circular pipe section each have a plurality of circular cross-section slurry channels arranged in a honeycomb pattern. The cross-sectional diameter of each of the slurry channels in the second slurry transport circular pipe section is smaller than the cross-sectional diameter of each of the slurry channels in the first slurry transport circular pipe section. The third slurry transport square pipe section has a plurality of rectangular cross-section slurry channels arranged in a honeycomb pattern. The rear end of the third slurry transport circular pipe section (i.e., the discharge end of the micro-turbulent fiber slurry) is connected to the inlet of the forming head. The cross-sectional area of ​​each of the slurry channels in the third slurry transport circular pipe section is smaller than the cross-sectional area of ​​each of the slurry channels in the second slurry transport circular pipe section. The mixed fiber slurry is injected into the inlet of the slurry dispenser, passes through the first slurry transport circular pipe section, the second slurry transport circular pipe section, and the third slurry transport circular pipe section, and is transported to the forming head as a micro-turbulent fiber slurry. The provision of a staged discharge section is a prerequisite for ensuring a thorough mixing of the long regenerated cellulose fibers and the short natural fibers without losing stability and for obtaining a uniform fiber web.

[0052] In the wet-laid web formation step S5 of the present invention, dehydration of the fibrous web is performed on the web forming machine. Dehydration is performed using a dehydration device (e.g., a dehydration box) located below the forming net of the web forming machine. During the dehydration process of the fibrous web, the dehydration effect can be controlled by controlling the valve of the dehydration chamber of the dehydration device. The valve of the dehydration chamber is controlled, for example, to 70% to 98%. The valve of the dehydration chamber may also be controlled to 70%, 80%, 90%, 98%, etc., or any value between 70% and 98%. Furthermore, a humidity sensor can be installed to control the humidity throughout the fibrous web, thereby achieving a more uniform humidity throughout the fibrous web. The humidity sensor detects changes in humidity in the environment and converts them into an electrical signal or other form of output for data processing and recording. In this embodiment, a capacitance-type humidity sensor can be used. The capacitance-type humidity sensor measures humidity and moisture content by utilizing changes in the capacitance of a material under different humidity conditions, and is characterized by high accuracy, fast response time, and insensitivity to temperature changes.

[0053] In step S6, the dewatered fiber web is transported to a hydroentangling device and hydroentangled. Hydroentangling utilizes a web support net to transport the fiber web under conditions of relatively low water jet pressure, multiple water jet heads, and small water jet nozzle spacing, forming regular through-holes on the surface of the nonwoven fabric. These through-holes allow the water-disintegratable spunlace nonwoven fabric to be hydrolyzed more quickly under water flow conditions.

[0054] In step S6, hydroentanglement is performed using three to seven (preferably six) water jet heads with a relatively low water jet pressure of 10 bar to 50 bar. The water jet heads may be arranged sequentially along the machine travel direction. Each water jet head has a plurality of water jet nozzles. Preferably, the nozzle diameter is 0.08 mm to 0.12 mm, and the nozzle spacing is 0.6 mm to 1.4 mm. The water jet pressure can be adjusted according to actual needs. The water jet pressure may be, for example, 10 bar, 20 bar, 30 bar, 40 bar, or 50 bar, or any other value between 10 bar and 50 bar. In addition, the hydroentanglement device is equipped with three to four (preferably four) negative pressure suction devices on either side of the water jet head across the fiber web. The hydroentangled fiber web can be dewatered by negative pressure suction from these negative pressure suction devices. The power of these negative pressure suction devices is set to 50% to 80%. These negative pressure suction devices may be arranged sequentially along the machine travel direction, but preferably arranged in order from highest power to lowest power. For example, the power of the first negative pressure suction device is set to 80%, the power of the second negative pressure suction device to 70%, the power of the third negative pressure suction device to 60%, and the power of the fourth negative pressure suction device to 50%. In this way, by setting the power of the negative pressure suction devices according to the moisture content of the fiber web, damage to the fiber web can be reduced and energy consumption can be reduced.

[0055] In the present invention, a light pressing step S7 is further provided. Lightly pressing the molded nonwoven fabric after spunlacing to set its shape can increase its wet strength. Here, light pressing means that the pressure is low. If the pressure is too high, the disintegration time in water increases. To ensure a disintegration time of less than 100 seconds, the pressing pressure may be 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, or 0.15 MPa, or any value between 0.1 MPa and 0.15 MPa, and is not particularly limited.

[0056] Infrared drying can be used in the drying step S8 of the present invention. Infrared drying can maintain the shape and texture of the water-disintegrable spunlace nonwoven fabric during the drying process, preventing deformation and tearing. Furthermore, infrared rays have a significant thermal effect and are easily absorbed by the web, quickly heating and evaporating the moisture on the web surface, achieving rapid drying. Compared to traditional hot air drying technology, infrared drying significantly reduces energy consumption and reduces emissions of pollutants such as carbon dioxide and nitrogen oxides, making it more environmentally friendly. Of course, the drying time and irradiation intensity of infrared drying can be adjusted according to the technical requirements of the water-disintegrable spunlace nonwoven fabric product to ensure drying quality and produce a flatter and smoother water-disintegrable spunlace nonwoven fabric.

[0057] In the drying step S8 of the present invention, a hot air-penetrating oven may be used. A hot air-penetrating oven accelerates the air flow by blowing hot air, thereby accelerating the drying process of the nonwoven fabric. During this process, the hot air acts as a drying medium and exchanges heat and moisture with the nonwoven fabric, causing moisture on the surface of the nonwoven fabric to evaporate and diffuse from the gas film on the surface into the main body of the airflow. Furthermore, as a result of evaporation on the surface of the article, a moisture gradient difference occurs between the interior and surface of the article, and the internal moisture diffuses to the surface in a gaseous or liquid state. In hot air-penetrating oven drying, the large surface area for heat and mass transfer between the gas and solid phases allows for rapid drying. Furthermore, due to its high thermal efficiency, long drying time, and large throughput, it can meet the needs of large-scale production. Furthermore, flash dryers have a simple structure, large production capacity, easy operation, and low capital investment costs.

[0058] In some preferred embodiments, the pre-treatment step S2 includes dividing the natural fibers into two parts, a first type of natural fibers and a second type of natural fibers; dividing the regenerated cellulose fibers prepared at a predetermined mass fraction into two parts, a first type of regenerated cellulose fibers and a second type of regenerated cellulose fibers; beating the first type of natural fibers and the second type of natural fibers so that the freeness of the first type of natural fibers is greater than the freeness of the second type of natural fibers; ultrasonically treating the second type of regenerated cellulose fibers to form pits on their surfaces, and not performing surface treatment on the first type of regenerated cellulose fibers.

[0059] Specifically, the natural fibers are divided into two parts, a first type of natural fiber and a second type of natural fiber, and the first type of natural fiber and the second type of natural fiber are separately beaten. Preferably, the beating degree of the first type of natural fiber is 35°SR to 41°SR, e.g., 35°SR, 36°SR, 37°SR, 38°SR, 39°SR, 40°SR, or 41°SR, and the beating degree of the second type of natural fiber is 18°SR to 30°SR, e.g., 18°SR, 19°SR, 20°SR, 21°SR, 22°SR, 23°SR, 24°SR, 25°SR, 26°SR, 27°SR, 28°SR, 29°SR, or 30°SR. By making the beating degree of the first type of natural fiber greater than that of the second type of natural fiber, the wet strength of the water-decomposable spunlace nonwoven fabric can be increased.

[0060] Preferably, the operating frequency of the ultrasonic generator is set to 15 kHz to 25 kHz, the power is set to 50 W to 1000 W, and the ultrasonic generator is operated for 5 minutes to 15 minutes at room temperature. When ultrasonic waves are applied to the second type of regenerated cellulose fibers, the high-frequency vibration and energy transmission characteristics of the ultrasound cause the vibration energy of the ultrasound to cause the displacement and vibration of the fiber surface molecules, resulting in the formation of micro-irregularities on the surface of the second type of regenerated cellulose fibers. The ultrasound also creates localized high- and low-pressure areas, resulting in micro-deformations on the surface of the second type of regenerated cellulose fibers. These deformations include small-scale peeling of the surface layer and material rearrangement, resulting in the formation of pits with a certain number and distribution.

[0061] The manufacturing method of this embodiment is a method for manufacturing the water-decomposable spunlace nonwoven fabrics of Examples 1 to 5. In some preferred embodiments, in the hydroentangling step S6, the angle between the water jet from the water jet head and the fibrous web is not 90°. This allows the through-holes of the water-disintegratable spunlace nonwoven fabric to be inclined. Inclined holes are more advantageous for the hydrolysis of the water-disintegratable spunlace nonwoven fabric and can shorten the hydrolysis time. The manufacturing method of this embodiment is a method for manufacturing the water-decomposable spunlace nonwoven fabrics in Table 6 above.

[0062] Comparison experiment The manufacturing method of a water-disintegrable spunlace nonwoven fabric of the same basis weight (43 gsm) in the prior art was used as a reference, with the viscose fiber content being 20-30%, the softwood pulp content being 70-80%, the viscose fiber fineness being 1.5D, and the length being 10 mm. The measurement data are shown in Table 7 below. As can be seen from Table 7 below, the water-disintegrable spunlace nonwoven fabric of the same basis weight in the prior art not only has low wet strength but also a long water disintegration time.

[0063] [Table 7]

[0064] While several specific embodiments of the present invention have been described in detail by way of example, those skilled in the art will appreciate that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art will appreciate that changes may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is limited by the appended claims.

Claims

1. The fabric comprises, by mass fraction, 60% to 85% natural fibers and 15% to 40% regenerated cellulose fibers having a length longer than that of the natural fibers; A water-disintegratable spunlace nonwoven fabric having a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a water disintegration time of less than 100 seconds, a wet strength in the MD direction of 3.0 N to 5.0 N, and a wet strength in the CD direction of 2.0 N to 3.5 N.

2. The natural fibers include a first type of natural fiber and a second type of natural fiber, and the first type of natural fiber has a higher beating degree than the second type of natural fiber; The water-decomposable spunlace nonwoven fabric according to claim 1, characterized in that the regenerated cellulose fibers include a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber, the surfaces of the first type of regenerated cellulose fiber are not deformed, and the surfaces of the second type of regenerated cellulose fiber have pits.

3. a mass ratio of the first type of natural fiber to the second type of natural fiber is 1:9 to 3:7; The water-decomposable spunlace nonwoven fabric according to claim 2, characterized in that the first type of natural fiber and the second type of natural fiber are made of the same material, both containing hardwood pulp and softwood pulp, and when the mass of the natural fibers is taken as 100%, the mass fraction of the hardwood pulp is 25% to 50% and the mass fraction of the softwood pulp is 50% to 75%.

4. the mass ratio of the first type of regenerated cellulose fibers to the second type of regenerated cellulose fibers is 7:3 to 9:1; the first type of regenerated cellulose fiber and the second type of regenerated cellulose fiber are made of the same material, and each of them contains one or two types selected from lyocell fiber and viscose fiber; The water-decomposable spunlace nonwoven fabric according to claim 2, wherein the lyocell fiber has a fineness of 0.9D to 1.5D and a length of 3mm to 10mm, and the viscose fiber has a fineness of 0.5D to 2.0D and a length of 3mm to 10mm.

5. The water-disintegrable spunlace nonwoven fabric according to claim 1, characterized in that the water-disintegrable spunlace nonwoven fabric has a plurality of through-holes aligned in the longitudinal and transverse directions.

6. The water-decomposable spunlace nonwoven fabric according to claim 5, characterized in that the water-decomposable spunlace nonwoven fabric has a first surface and a second surface opposing each other in the thickness direction, and the angle formed between the through hole and the first surface is an obtuse angle, and the angle formed between the through hole and the second surface is an acute angle.

7. A method for producing a water-disintegrable spunlace nonwoven fabric according to any one of claims 1 to 6, comprising: a raw material preparation step of preparing natural fibers and regenerated cellulose fibers at a predetermined mass fraction; a pre-treatment step of pre-treating the natural fibers and the regenerated cellulose fibers; a slurry preparation step of thoroughly mixing the pre-treated natural fibers and regenerated cellulose fibers with water to prepare a slurry having a concentration of 3% by mass to 6% by mass; a step of gradually diluting and mixing the mixture to obtain a micro-turbulent slurry having a concentration of 0.02% by mass to 0.05% by mass, and supplying the micro-turbulent slurry to a forming head; a wet-type web forming process in which the micro-turbulent slurry is directly sprayed from a forming head onto a forming net of a web forming machine to form a uniform fiber web, the fiber web is dehydrated by a dehydration device located below the forming net, and the humidity is controlled by a humidity sensor; a hydroentangling step in which the dewatered fiber web is transported to a hydroentangling device, and the fiber web is hydroentangled by three to four stages of negative pressure suction while being hydroentangled by water jets at a relatively low pressure of 10 bar to 50 bar using three to seven water jet heads, thereby obtaining a molded nonwoven fabric; a light pressing step of lightly pressing the molded nonwoven fabric at a pressure of 0.1 MPa to 0.15 MPa; and a drying step of drying the lightly pressed molded nonwoven fabric by infrared drying or hot air penetration oven drying.

8. The pre-treatment step comprises: dividing the natural fibers into two portions, a first type of natural fibers and a second type of natural fibers; Dividing the regenerated cellulose fibers prepared in a predetermined mass fraction into two parts, a first type of regenerated cellulose fibers and a second type of regenerated cellulose fibers; beating the first type of natural fibers and the second type of natural fibers so that the degree of beating of the first type of natural fibers is greater than the degree of beating of the second type of natural fibers; The method for producing a water-decomposable spunlace nonwoven fabric according to claim 7, characterized in that it comprises subjecting the second type of regenerated cellulose fibers to ultrasonic treatment to form pits on their surfaces, and not subjecting the first type of regenerated cellulose fibers to surface treatment.

9. The method for producing a water-decomposable spunlace nonwoven fabric according to claim 7, wherein in the hydroentanglement step, the angle between the water jet from the water jet head and the fiber web is not 90°.

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