Water-soluble spunlace nonwoven fabric and method for producing the same

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 spunlace nonwoven products and production processes, and more specifically, to hydrolyzable spunlace nonwoven fabrics and their manufacturing methods.

Background Art

[0002] Hydrolyzable nonwoven fabrics loosen when in contact with water and do not clog toilets or sewers. Currently, hydrolyzable nonwoven fabrics are formed into fiber webs by a web forming process using natural fibers, regenerated cellulose fibers, etc. After that, it is necessary to go through the most important process of reinforcing the fiber web so that the hydrolyzable nonwoven product has good wet usability while having hydrolyzability. Currently, generally, there are mainly three methods for reinforcing hydrolyzable nonwoven fabrics: chemical adhesion, thermal adhesion, and spunlace.

[0003] The key to reinforcing hydrolyzable nonwoven fabrics by the chemical adhesion method is to use a special adhesive that dissolves by the shear and flushing of water flow to put the fibers in a hydrolyzed state. The type of adhesive used in this method plays a decisive role in the goodness or badness of the hydrolyzability of the product, and the safety and irritation of chemical reagents are also important considerations. Hydrolyzable nonwoven fabrics by the thermal adhesion method are manufactured by mixing a small amount of heat-meltable fibers and cellulose fibers and processing them into a fiber web, and then melting the heat-meltable fibers by heating means such as hot pressing or hot air to adhere and reinforce the cellulose fibers. Generally, as heat-meltable fibers, there are ES fibers, polylactic acid fibers (PLA), polyethylene fibers, polypropylene fibers, etc. However, since heat-meltable fibers usually do not have 100% biodegradability, if used in a large amount, non-degradable fibers will accumulate in the sewage treatment system, increasing the load of sewage treatment. Therefore, the spunlace method is widely used because it is more environmentally friendly. However, nonwoven fabrics manufactured by the conventional spunlace method have low wet strength and are easily broken during use, or have too high wet strength and a long hydrolysis time, clogging toilets or sewers. Therefore, it is urgent to provide a hydrolytic spunlace nonwoven fabric with a short hydrolysis time and high wet strength, as well as a method for producing the same. [Overview of the project] [Problems that the invention aims to solve]

[0004] Therefore, the present invention provides a hydrolyzable spunlace nonwoven fabric that can be quickly hydrolyzed and has high wet strength, as well as a method for producing the same. [Means for solving the problem]

[0005] The present invention comprises, by mass fraction, 60% to 85% natural fibers and 15% to 40% regenerated cellulose fibers whose length is longer than that of the natural fibers, has a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a thawing time of less than 100 s, and a wet strength in the MD direction. 3.0N / 50mm~5.0N / 50mm The wet strength in the CD direction is 2.0N / 50mm~3.5N / 50mm We are releasing a water-soluble spunlace nonwoven fabric.

[0006] Furthermore, the present invention relates to a method for producing a hydrolyzable spunlace nonwoven fabric, comprising: a raw material preparation step of preparing natural fibers and regenerated cellulose fibers in a predetermined mass fraction; a pretreatment step of pre-treating the natural fibers and 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 with a concentration of 3% to 6% by mass; and a stepwise dilution and mixing to obtain a slurry of microturbulence with a concentration of 0.02% to 0.05% by mass, and molding this microturbulence slurry. head The process involves preparing the slurry to be supplied to the web forming machine, spraying the slurry in a micro-turbulent flow directly from the forming head to the forming net of the web forming machine to form a uniform fiber web, dewatering the fiber web using a dewatering device located below the forming net, and controlling the humidity with a humidity sensor in a wet web forming process, and then transporting the dewatered fiber web to a water flow entanglement device, where the water jet pressure is controlled using 3 to 7 water jet heads. 1 MPa (10 bar) to 5 MPa (50 bar)This invention discloses a method for manufacturing a hydrolytic spunlace nonwoven fabric, which includes a water flow entanglement step in which the fiber web is entangled with a relatively low-pressure water jet and dewatered by 3 to 4 stages of negative pressure suction to obtain a molded nonwoven fabric; a light pressing step in which the molded nonwoven fabric is lightly pressed with a press pressure of 0.1 MPa to 0.15 MPa; and a drying step in which the lightly pressed molded nonwoven fabric is dried by infrared drying or hot air permeable oven drying. [Effects of the Invention]

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

[0008] In this invention, by combining natural fibers and regenerated cellulose fibers of different fineness and length, the fibers intertwine in the spatial structure, forming a dense fiber layer structure, and in the fiber orientation, the tensile strength in the direction of mechanical movement is higher than the tensile strength perpendicular to the direction of mechanical movement. 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 hole spacing, regular pores are formed on the surface of the nonwoven fabric through water flow entanglement. These pores allow the hydrolyzable spunlace nonwoven fabric to dehydrate more rapidly under water flow conditions. By dewatering the fibers by negative pressure suction, the nonwoven fabric changes from a saturated bulk state to a dense state. This increases contact between fibers, increases the bonding area between fibers, and improves the hydrogen bonding ability of the fibers. Therefore, the hydrolyzable spunlace nonwoven fabric of this invention has a dehydration time of less than 100 s, and the wet strength in the MD direction is 3.0N / 50mm~5.0N / 50mm The wet strength in the CD direction is 2.0N / 50mm~3.5N / 50mm It dissolves quickly in water and has high wet strength.

[0009] Of course, any product implementing the present invention does not necessarily need to achieve all of the above technical effects simultaneously. Other features and advantages of the present invention will become apparent from the detailed description of exemplary embodiments of the present invention with reference to the drawings below. [Brief explanation of the drawing]

[0010] The drawings incorporated into the specification and constituting part of the specification illustrate embodiments of the present invention and are used to explain the mechanism of the present invention together with the description thereof. [Figure 1] This is a schematic plan view of the water-soluble spunlace nonwoven fabric of the present invention. [Figure 2] This is a magnified section of Figure 1. [Figure 3] This is another enlarged view of Figure 1. [Figure 4] This is a flowchart of the method for producing a hydrolyzable spunlace nonwoven fabric provided by the present invention. [Modes for carrying out the invention]

[0011] Hereinafter, various exemplary embodiments of the present invention will be described in detail with reference to the drawings. The relative arrangements of components and processes, formulas, and numerical values ​​described in these embodiments do not limit the scope of the present invention unless otherwise specified. The following description relating to at least one exemplary embodiment is illustrative only and does not limit the invention or its applications or uses.

[0012] While some technologies, methods, and apparatus known to those skilled in the art may not be described in detail, these technologies, methods, and apparatus should be considered as part of the specification where necessary. All specific values ​​in the examples shown and described herein should be interpreted as merely illustrative and not restrictive. Therefore, the values ​​may differ in other examples of the exemplary embodiments.

[0013] In the following drawings, the same reference numbers and letters represent the same items. Therefore, if an item is defined in one drawing, it does not need to be further explained in subsequent drawings. Refer to FIGS. 1, 2 and 3. FIG. 1 is a schematic plan view of the hydrolyzable spunlace nonwoven fabric of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is another partially enlarged view of FIG. 1. FIGS. 2 and 3 have different magnification ratios. The present invention includes, by mass fraction, 60% to 85% of natural fibers and 15% to 40% of regenerated cellulose fibers having a length longer than that of the natural fibers, has a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a hydrolysis time of less than 100 s, and a wet strength in the MD direction of 3.0N / 50mm~5.0N / 50mm and a wet strength in the CD direction of 2.0N / 50mm~3.5N / 50mm to provide a hydrolyzable spunlace nonwoven fabric.

[0014] In addition, in the present invention, the measurement of wet strength is carried out according to "GB / T 24218.3 Test methods for nonwovens - Part 3: Determination of breaking strength and elongation at break (strip method)". Specifically, five or more samples are cut out in the longitudinal direction (machine running direction) and the transverse direction (width direction of the nonwoven fabric) of the hydrolyzable spunlace nonwoven fabric sample so that the longitudinal direction of the sample is parallel to the longitudinal direction (machine running direction) and the transverse direction (width direction of the nonwoven fabric), respectively. The width of the sample 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 longitudinal direction, and the strength in the CD direction is the breaking strength in the transverse direction. Also, the measurement of hydrolysis time (ease of loosening) is carried out according to JIS P 4501. The measurement of basis weight is carried out according to GB / T 24218.1. The measurement of thickness is carried out according to GB / T 24218.2.

[0015] Example 1 The hydrolyzable spunlace nonwoven fabric of this example is manufactured by a wet forming and spunlace process, and includes, by mass fraction, 70% of natural fibers and 30% of regenerated cellulose fibers having a length longer than that of the natural fibers, has a basis weight of 35 gsm, a thickness of 0.3 mm, and a hydrolysis time of less than 100 s. Specific parameter data are shown in Table 1 below.

[0016]

Table 1

[0017] Example 2 The hydrolyzable spunlace non-woven fabric of this example is manufactured by a wet forming and a spunlace process, and contains, by mass fraction, 70% natural fiber and 30% regenerated cellulose fiber with a length longer than that of the natural fiber, has a basis weight of 40 gsm, a thickness of 0.4 mm, and a hydrolysis time of less than 100 s. Specific parameter data are shown in Table 2 below.

[0018]

Table 2

[0019] Example 3 The hydrolyzable spunlace non-woven fabric of this example is manufactured by a wet forming and a spunlace process, and contains, by mass fraction, 75% natural fiber and 25% regenerated cellulose fiber with a length longer than that of the natural fiber, has a basis weight of 45 gsm, a thickness of 0.42 mm, and a hydrolysis time of less than 100 s. Specific parameter data are shown in Table 3 below.

[0020]

Table 3

[0021] Example 4 The hydrolyzable spunlace non-woven fabric of this example is manufactured by a wet forming and a spunlace process, and contains, by mass fraction, 80% natural fiber and 20% regenerated cellulose fiber with a length longer than that of the natural fiber, has a basis weight of 50 gsm, a thickness of 0.43 mm, and a hydrolysis time of less than 100 s. Specific parameter data are shown in Table 4 below.

[0022]

Table 4

[0023] Example 5 The hydrolytic spunlace nonwoven fabric of this embodiment was manufactured by wet molding and spunlace processes, and by mass fraction, contained 85% natural fibers and 15% regenerated cellulose fibers whose length was longer than that of the natural fibers, with a basis weight of 55 gsm, a thickness of 0.43 mm, and a hydrolysis time of less than 100 s. Specific parameter data are shown in Table 5 below.

[0024] [Table 5]

[0025] In some preferred embodiments, the natural fibers comprise a first type of natural fiber and a second type of natural fiber, wherein the degree of beating of the first type of natural fiber is greater than the degree of beating of the second type of natural fiber, and the regenerated cellulose fibers comprise a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber, wherein the surface of the first type of regenerated cellulose fiber is undeformed and the surface of the second type of regenerated cellulose fiber has pits.

[0026] Furthermore, the natural fibers are divided into two parts: a first type of natural fiber and a second type of natural fiber. The first and second types of natural fibers are beaten so that the degree of beatenness of the first type of natural fiber is greater than that of the second type of natural fiber. Preferably, the degree of beatenness 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, 41°SR, and the degree of beatenness 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, 30°SR. Here, the mass percentages of the first and second types of natural fibers are not equal. The mass percentage of the first type of natural fiber may be less than the mass percentage of the second type of natural fiber. By increasing the degree of beating of the first type of natural fiber compared to the degree of beating of the second type of natural fiber, the wet strength of the water-soluble spunlace nonwoven fabric can be increased.

[0027] Furthermore, the regenerated cellulose fibers are divided into two parts: a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber. The surface of the first type of regenerated cellulose fiber remains unchanged, while the surface of the second type of regenerated cellulose fiber has pits. The pits improve the bonding between the second type of regenerated cellulose fiber and the natural fibers, thereby increasing the wet strength of the hydrolyzable spunlace nonwoven fabric.

[0028] The natural fibers used in Examples 1 to 5 above are the first type of natural fiber and the second type of natural fiber of this embodiment. The regenerated cellulose fibers used in Examples 1 to 5 above are the first type of regenerated cellulose fiber and the second type of regenerated cellulose fiber 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 of the same material and both contain hardwood pulp and softwood pulp, and when the mass of the natural fiber is taken as 100%, the mass fraction of hardwood pulp is 25% to 50% and the mass fraction of softwood pulp is 50% to 75%.

[0029] The length of natural fibers is 1 mm to 3 mm; for example, the length of coniferous 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. Since the fiber length of hardwood pulp and softwood pulp is usually shorter than that of regenerated cellulose fibers, they can give hydrolytic spunlace nonwoven fabrics 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] The mass ratio of the first type of natural fiber to the second type of natural fiber may be 1:9, 2:8, or 3:7, and of course, it may be any mass ratio between 1:9 and 3:7, and is not particularly limited. The first and second types of natural fibers are made of the same material and both contain hardwood pulp and softwood pulp. However, the first and second types of natural fibers have different degrees of beating, with the first type having a higher degree of beating than the second type. This increases the wet strength of the water-soluble spunlace nonwoven fabric. However, the mass percentage of the first type of natural fiber should not be too high. If the mass percentage of the first type of natural fiber is too high, the wet strength will become too high, and the thawing time will become too long. In this embodiment, in order to ensure that the thawing time is less than 100 seconds, the mass ratio of the first type of natural fiber to the second type of natural fiber is set to 1:9 to 3:7. As a result, the water-soluble spunlace nonwoven fabric has high wet strength while having a thawing time of less than 100 seconds.

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

[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 viscose fibers 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, or 2D, or any value between 0.5D and 2.0D. The length may be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 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 each contains one or two types selected from lyocell fibers and viscose fibers. However, the surface of the first type of regenerated cellulose fiber does not deform, and the surface of the second type of regenerated cellulose fiber has pits. The pits improve the bonding between the second type of regenerated cellulose fiber and the natural fibers, and can increase the wet strength of the hydrolyzable 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 become too high, and the hydrolysis time will become too long. In this embodiment, in order to ensure that the hydrolysis time is less than 100 s, 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. As a result, the hydrolyzable spunlace nonwoven fabric has high wet strength while having a hydrolysis time of less than 100 s.

[0034] In Example 1 described above, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 30%, of which lyocell fibers make up 15% and viscose fibers make up 15%. The fineness of the lyocell fibers is 1.0D and the length is 6mm, while the fineness of the viscose fibers is 1.0D and the length is 8mm.

[0035] In Example 2 described above, when the mass of the hydrolyzable spunlace nonwoven fabric is set to 100%, the mass fraction of regenerated cellulose fibers is 30%, of which lyocell fibers make up 20% and viscose fibers make up 10%. The fineness of the lyocell fibers is 1.0D and the length is 6mm, while the fineness of the viscose fibers is 1.0D and the length is 8mm.

[0036] In Example 3 described above, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 25%, of which lyocell fibers make up 5% and viscose fibers make up 20%. The fineness of the lyocell fibers is 1.0D and the length is 6mm, while the fineness of the viscose fibers is 1.5D and the length is 8mm.

[0037] In another embodiment of the present invention, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 15%, of which lyocell fibers make up 5% and viscose fibers make up 10%, the fineness of the lyocell fibers is 1.0D and the length is 6 mm, and the fineness of the viscose fibers is 1.0D and the length is 8 mm.

[0038] In another embodiment of the present invention, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 20%, of which lyocell fibers make up 15% and viscose fibers make up 5%. The fineness of the lyocell fibers is 1.0D and the length is 6 mm, and the fineness of the viscose fibers is 1.0D and the length is 8 mm.

[0039] In other words, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 15% to 40%, of which the lyocell fiber content is 5% to 20%, the fineness of the lyocell fibers is 1.0D and the length is 6mm, and the viscose fiber content is 5% to 20%, the fineness of the viscose fibers is 1.0D or 1.5D and the length is 8mm.

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

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

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

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

[0044] In other words, when the mass of the hydrolyzable spunlace nonwoven fabric is taken as 100%, the mass fraction of regenerated cellulose fibers is 15% to 40%, of which 5% to 10% are lyocell fibers with a fineness of 1.0D and a length of 6mm, 5% to 10% are lyocell fibers with a fineness of 1.0D and a length of 8mm, 3% to 10% are viscose fibers with a fineness of 1.0D and a length of 8mm, and 2% to 10% are viscose fibers with a fineness of 1.5D and a length of 10mm.

[0045] As described above, by combining lyocell fibers and viscose fibers with different fineness and length, it is possible to increase strength, improve solubility, and shorten solubility. Refer to Figure 1 again. In some preferred embodiments, the hydrolytic spunlace nonwoven fabric has a plurality of through-holes arranged in the longitudinal and width directions. The through-holes are formed by the spunlace process. Here, the longitudinal direction is the direction of the nonwoven fabric's movement during manufacturing (machine direction), and the width direction is perpendicular to the direction of the nonwoven fabric's movement.

[0046] 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 hole spacing, water flow entanglement creates regular holes (i.e., through-holes) on the surface of the nonwoven fabric. These holes (i.e., through-holes) allow the hydrolyzable spunlace nonwoven fabric to dehydrate more rapidly under water flow conditions. In some preferred embodiments, the hydrolytic spunlace nonwoven fabric has opposing first and second surfaces in the thickness direction, with an obtuse angle between the through-hole and the first surface and an acute angle between the through-hole and the second surface.

[0047] In this embodiment, the through-holes are inclined holes, not vertical holes. The angle between the through-hole and the first surface is obtuse, and the angle between the through-hole and the second surface is acute. Here, the first surface is the surface of the hydrolyzable spunlace nonwoven fabric, and the second surface is the back surface of the hydrolyzable spunlace nonwoven fabric. Having inclined holes is advantageous for the hydrolysis of the hydrolyzable spunlace nonwoven fabric and can shorten the hydrolysis time. It has been confirmed that when the through-holes are inclined, the hydrolysis time is shortened by 5 to 8 seconds compared to when the through-holes are vertical. The performance parameters of the hydrolyzable spunlace nonwoven fabric when the through-holes are inclined are shown in Table 6 below. Preferably, the obtuse angle is 90° or more and 115° or less, and the acute angle is 75° or less and less than 90°.

[0048] [Table 6]

[0049] In some preferred embodiments, antimicrobial nanoparticles are sprayed onto the surface of a hydrolyzable spunlace nonwoven fabric. Preferably, antimicrobial nanoparticles, such as nanomaterials with antimicrobial properties, are spray-coated onto the surface of the hydrolyzable spunlace nonwoven fabric. These antimicrobial nanoparticles possess antimicrobial properties without affecting the hydrolyzability. Preferably, plant extracts such as aloe vera or honeysuckle can be used as antibacterial components. By preparing plant extracts such as aloe vera or honeysuckle into antibacterial nanoparticles and spraying them onto the surface of a hydrolyzable spunlace nonwoven fabric, antibacterial properties can be achieved, and health benefits can also be obtained.

[0050] Based on the same inventive concept, the present invention further provides a method for producing the above-mentioned hydrolyzable spunlace nonwoven fabric. Refer to Figure 4. Figure 4 is a flowchart of the method for producing the hydrolyzable spunlace nonwoven fabric provided by the present invention. Such a manufacturing method includes the following steps. Raw material preparation process S1: Natural fibers and regenerated cellulose fibers are prepared in predetermined mass fractions. Pre-treatment step S2: Pre-treatment of natural fibers and regenerated cellulose fibers. Slurry preparation step S3: The pre-treated 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 preparation process S4: Dilution and mixing are performed in stages to obtain a slurry with a concentration of 0.02% to 0.05% by mass and a micro-turbulent flow, and this micro-turbulent slurry is molded. head To supply. Wet web formation process S5: A slurry of microturbulence is sprayed directly from the molding head to the molding net of the web forming machine to form a uniform fiber web. The fiber web is then dewatered by a dewatering device located below the molding net, and the humidity is controlled by a humidity sensor. Water flow entanglement process S6: The dewatered fiber web is transported to a water flow entanglement device, and the water jet pressure is applied using 3 to 7 water jet heads. 1 MPa (10 bar) to 5 MPa (50 bar) A molded nonwoven fabric is obtained by entangling the fiber web with a relatively low-pressure water jet, and then dewatering the fiber web with 3-4 stages of negative pressure suction. Light pressing process S7: The molded nonwoven fabric is lightly pressed with a pressing pressure of 0.1 MPa to 0.15 MPa. Drying process S8: The lightly pressed molded nonwoven fabric is dried by infrared drying or hot air permeable oven drying. Specifically, in slurry preparation step S3, the slurry concentration may be any value between 3% by mass and 6% by mass. For example, it may be 3% by mass, 4.0% by mass, 4.5% by mass, 5% by mass, 5.5% by mass, or 6% by mass.

[0051] In the slurry preparation step S4, a stepwise dilution mixing method is employed, that is, the slurry is diluted in stages from a high concentration to a low concentration. As an example, for instance, the slurry is first diluted to 2% by mass, then diluted from 2% to 1% by mass, further diluted from 1% to 0.1% by mass, and finally diluted from 0.1% to 0.05% by mass. You can refer to publication number CN106351053A, the invention titled "Method for producing hydrolyzable and biodegradable spunlace nonwoven fabric by stepwise mixing method". In this method, a stepwise discharge section is installed to mix the slurry in stages. Specifically, the stepwise discharge section is connected to the discharge port of a slurry dispenser (preferably a conical slurry dispenser). The stepwise discharge section includes a first slurry transport circular pipe section, a second slurry transport circular pipe section, and a third slurry transport rectangular pipe section, which are connected in sequence. The first slurry transport circular pipe section and the second slurry transport circular pipe section each consist of multiple slurry channels with a circular cross-section arranged in a honeycomb pattern. The cross-sectional diameter of each slurry channel in the second slurry transport circular pipe section is smaller than the cross-sectional diameter of each slurry channel in the first slurry transport circular pipe section. The third slurry transport rectangular pipe section consists of multiple slurry channels with a square cross-section arranged in a honeycomb pattern. The rear end of the third slurry transport rectangular pipe section (i.e., the discharge end for the micro-turbulent fiber slurry) is continuous with the injection port of the molding head. The cross-sectional area of ​​each slurry channel in the third slurry transport rectangular pipe section is smaller than the cross-sectional area of ​​each slurry channel in the second slurry transport circular pipe section. The mixed fiber slurry is injected into the injection port 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 rectangular pipe section, and is transported to the molding head as a micro-turbulent fiber slurry. The installation of a stepped discharge section is a prerequisite for ensuring sufficient mixing of regenerated cellulose long fibers and natural short fibers without losing stability, and for obtaining a uniform fiber web.

[0052] In the wet web forming process S5 of the present invention, dewatering of the fiber web is performed on the web forming machine. Dewatering is performed by a dewatering device (e.g., a dewatering box) located below the forming net of the web forming machine. During the dewatering process of the fiber web, the dewatering effect can be controlled by controlling the valve of the dewatering chamber of the dewatering device. The valve of the dewatering chamber is controlled, for example, to 70% to 98%. The valve of the dewatering chamber may be controlled to 70%, 80%, 90%, 98%, etc., or to any value between 70% and 98%. Furthermore, by providing a humidity sensor to control the humidity of the entire fiber web, the humidity of the fiber web can be made more uniform. The humidity sensor senses changes in humidity in the environment and converts it into an electrical signal or other form of output for data processing and recording. In this embodiment, a capacitive humidity sensor can be used. A capacitive humidity sensor measures humidity and moisture content by utilizing the change in capacitance of a material under different humidity conditions, and has the characteristics of high accuracy, fast response time, and low susceptibility to temperature changes.

[0053] In step S6, the dewatered fiber web is transported to a water entanglement device for water entanglement. Water entanglement creates regular through-holes on the surface of the nonwoven fabric 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 spacing between water jet holes. These through-holes allow the water-soluble spunlace nonwoven fabric to dehydrate more quickly under water flow conditions.

[0054] In step S6, using a plurality of water jet heads, 3 to 7 (preferably 6), the water jet pressure is 1 MPa (10 bar) to 5 MPa (50 bar)Water flow entanglement is achieved using a relatively low-pressure water jet. Multiple water jet heads can be arranged sequentially along the direction of machine movement. Each water jet head is provided with multiple water jet nozzles. Preferably, the diameter of these nozzles is 0.08 mm to 0.12 mm, and the spacing between them is 0.6 mm to 1.4 mm. The water jet pressure can be adjusted according to the actual needs. The water jet pressure can be, for example, 1 MPa (10 bar), 2 MPa (20 bar), 3 MPa (30 bar), 4 MPa (40 bar), or 5 MPa (50 bar) Even if that's the case, of course 1 MPa (10 bar) to 5 MPa (50 bar) Any other value between these two values ​​may be used. In addition, the water flow entanglement device is equipped with 3 to 4 (preferably 4) negative pressure suction devices on the opposite side of the water jet head from the fiber web. The negative pressure suction from these negative pressure suction devices can dewater the fiber web that is entangled in water flow. The power of these negative pressure suction devices is set to 50% to 80%. These negative pressure suction devices can be arranged sequentially along the direction of machine movement, but it is preferable to arrange them in order from high power to low power. For example, the power of the first negative pressure suction device can be 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%. By setting the power of the negative pressure suction devices according to the moisture content in the fiber web in this way, damage to the fiber web can be reduced, and energy consumption can be reduced.

[0055] In this invention, a light pressing step S7 is further provided. By lightly pressing the molded nonwoven fabric after spunlacing to adjust its shape, the wet strength can be increased. Here, light pressing means that the pressure is low. If the pressure is too high, the thawing time will increase. In order to ensure a thawing time of less than 100 s, the pressing pressure may be 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, or any value between 0.1 MPa and 0.15 MPa, and is not particularly limited.

[0056] In the drying process S8 of the present invention, infrared drying can be used. Infrared drying can maintain the shape and texture of the hydrolyzable spunlace nonwoven fabric during the drying process, avoiding deformation and tearing. Furthermore, infrared rays have a significant thermal effect and are easily absorbed by the web, so they can quickly heat and evaporate moisture on the web surface, achieving rapid drying. Compared to conventional hot air drying technology, infrared drying can significantly reduce energy consumption and reduce the emission 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 to ensure drying quality and make the hydrolyzable spunlace nonwoven fabric flatter and smoother, according to the technical requirements of the hydrolyzable spunlace nonwoven fabric product.

[0057] In the drying step S8 of the present invention, a hot air through-type oven drying may be used. A hot air through-type oven accelerates the drying process of the nonwoven fabric by speeding up the airflow through the blowing of hot air. In this process, the hot air exchanges moist heat with the nonwoven fabric as a drying medium, and the moisture on the surface of the nonwoven fabric evaporates and diffuses from the gaseous film on the surface into the airflow body. As a result of vaporization on the surface of the article, a moisture gradient difference is created between the inside and the surface of the article, and the moisture inside diffuses to the surface in a gaseous or liquid state. In hot air through-type oven drying, the surface area for heat transfer and mass transfer between the two phases of gas and solid is large, so the drying speed is fast. In addition, it has high thermal efficiency, a long drying time, and a large processing capacity, so it can meet the needs of large-scale production. Furthermore, airflow dryers have a simple structure, high production capacity, are easy to operate, and have low capital investment costs.

[0058] In some preferred embodiments, the pretreatment step S2 includes dividing natural fibers into two parts: a first type of natural fiber and a second type of natural fiber; dividing regenerated cellulose fibers prepared in a predetermined mass fraction into two parts: a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber; beating the first type of natural fiber and the second type of natural fiber respectively such that the degree of beating of the first type of natural fiber is greater than the degree of beating of the second type of natural fiber; ultrasonically treating the second type of regenerated cellulose fiber to form pits on its surface, while not performing surface treatment on the first type of regenerated cellulose fiber.

[0059] Specifically, the natural fibers are divided into two parts: a first type of natural fiber and a second type of natural fiber, and each of the two types of natural fibers is beaten. Preferably, the degree of beatenness for 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, 41°SR, and the degree of beatenness for the second type of natural fiber is 18°SR to 30°SR, for example, 18°SR, 19°SR, 20°SR, 21°SR, 22°SR, 23°SR, 24°SR, 25°SR, 26°SR, 27°SR, 28°SR, 29°SR, 30°SR. By making the degree of beatenness for the first type of natural fiber greater than that for the second type of natural fiber, the wet strength of the water-soluble spunlace nonwoven fabric can be increased.

[0060] Preferably, the ultrasonic generator is set to an operating frequency of 15kHz to 25kHz, a power output of 50W to 1000W, and the ultrasonic operation is performed at room temperature for 5 to 15 minutes. When ultrasound acts on the second type of regenerated cellulose fiber, the high-frequency vibrations and energy transfer characteristics of the ultrasound cause the vibrational energy to displace and vibrate the fiber surface molecules, resulting in the formation of minute irregularities on the surface of the second type of regenerated cellulose fiber. In addition, ultrasound creates localized high-pressure and low-pressure regions, resulting in minute deformations of the surface of the second type of regenerated cellulose fiber. These deformations include small-scale delamination of the surface layer and rearrangement of the material, forming pits of a certain number and distribution.

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

[0062] Comparative experiment Based on the conventional method for manufacturing a hydrolyzable spunlace nonwoven fabric of the same basis weight (43 gsm), the viscose fiber content was set to 20-30%, the softwood pulp content to 70-80%, the viscose fiber fineness to 1.5D, and the length to 10 mm. The measurement data is shown in Table 7 below. As can be seen from Table 7 below, the hydrolyzable spunlace nonwoven fabric of the same basis weight manufactured using the conventional method not only has low wet strength but also a long hydrolysis time.

[0063] [Table 7]

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

Claims

1. It contains, by mass fraction, 60% to 85% natural fibers and 15% to 40% regenerated cellulose fibers whose length is longer than that of the natural fibers. A hydrolytic spunlace nonwoven fabric characterized by a basis weight of 35 gsm to 55 gsm, a thickness of 0.3 mm to 0.5 mm, a hydrolysis time of less than 100 s, a wet strength in the MD direction of 3.0 N / 50 mm to 5.0 N / 50 mm, and a wet strength in the CD direction of 2.0 N / 50 mm to 3.5 N / 50 mm.

2. The aforementioned natural fibers include a first type of natural fiber and a second type of natural fiber, wherein the degree of beating of the first type of natural fiber is greater than the degree of beating of the second type of natural fiber. The hydrolytic spunlace nonwoven fabric according to claim 1, wherein the regenerated cellulose fibers include a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber, 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.

3. The mass ratio of the first type of natural fiber to the second type of natural fiber is 1:9 to 3:

7. The water-soluble spunlace nonwoven fabric according to claim 2, characterized in that the first type of natural fiber and the second type of natural fiber are of the same material, both containing hardwood pulp and softwood pulp, and when the mass of the natural fiber is taken as 100%, the mass fraction of hardwood pulp is 25% to 50% and the mass fraction of softwood pulp is 50% to 75%.

4. The mass ratio of the first type of regenerated cellulose fiber to the second type of regenerated cellulose fiber is 7:3 to 9:

1. The first type of regenerated cellulose fiber and the second type of regenerated cellulose fiber have the same material and each includes one or two types selected from lyocell fibers and viscose fibers. The water-soluble spunlace nonwoven fabric according to claim 2, characterized in that the lyocell fibers have a fineness of 0.9D to 1.5D and a length of 3 mm to 10 mm, and the viscose fibers have a fineness of 0.5D to 2.0D and a length of 3 mm to 10 mm.

5. The water-soluble spunlace nonwoven fabric according to claim 1, characterized in that it has a plurality of through holes arranged in the longitudinal direction and the width direction.

6. The water-soluble spunlace nonwoven fabric according to claim 5, wherein the water-soluble spunlace nonwoven fabric has opposing first and second surfaces in the thickness direction, the angle between the through-hole and the first surface is obtuse, and the angle between the through-hole and the second surface is acute.

7. A method for producing a water-soluble spunlace nonwoven fabric according to any one of claims 1 to 6, A raw material preparation process in which natural fibers and regenerated cellulose fibers are prepared in predetermined mass fractions, A pre-treatment step for pre-treating the natural fibers and the regenerated cellulose fibers, A slurry preparation step involves thoroughly mixing pre-treated natural fibers and regenerated cellulose fibers with water to prepare a slurry with a concentration of 3% to 6% by mass, A slurry preparation process involves gradually diluting and mixing to obtain a slurry with a concentration of 0.02% to 0.05% by mass, and supplying this slurry to the molding head. A wet web formation process involves spraying a slurry of microturbulence directly from a molding head onto the molding net of a web forming machine to form a uniform fiber web, dewatering the fiber web using a dewatering device located below the molding net, and controlling the humidity with a humidity sensor. The dewatered fiber web is transported to a water entanglement device, where the fiber web is entangled with water jets at a relatively low pressure of 1 MPa to 5 MPa using 3 to 7 water jet heads, while the fiber web is dewatered by 3 to 4 stages of negative pressure suction to obtain a molded nonwoven fabric. A light pressing step is performed in which the molded nonwoven fabric is lightly pressed with a press pressure of 0.1 MPa to 0.15 MPa, A method for producing a hydrolyzable spunlace nonwoven fabric, characterized by comprising a drying step of drying a lightly pressed molded nonwoven fabric by infrared drying or hot air permeable oven drying.

8. The aforementioned preliminary processing step is: Dividing natural fibers into two parts: Type 1 natural fibers and Type 2 natural fibers. The process involves dividing regenerated cellulose fibers, prepared in a predetermined mass fraction, into two parts: a first type of regenerated cellulose fiber and a second type of regenerated cellulose fiber. Beating the first type of natural fiber and the second type of natural fiber such that the degree of beaten of the first type of natural fiber is greater than the degree of beaten of the second type of natural fiber, A method for producing a hydrolytic spunlace nonwoven fabric according to claim 7, characterized in that the second type of regenerated cellulose fiber is ultrasonically treated to form pits on its surface, and the first type of regenerated cellulose fiber is not surface treated.

9. The method for producing a hydrolytic spunlace nonwoven fabric according to claim 7, characterized in that, in the water flow entanglement step, the angle between the water jet from the water jet head and the fiber web is not 90°.

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