Bicomponent Spunbond Nonwoven Fabric and Method for Manufacturing the Same

Abstract

A method for manufacturing a bicomponent spunbond nonwoven fabric includes a sheath-core filament, wherein a core component of the filament includes polypropylene, wherein a sheath component of the filament includes bio-polyethylene, and wherein the method includes: drawing the filament; supplying hot air to the drawn filament to form a fiber web; and bonding the fiber web.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is based upon and claims the benefit of priority from Korean Patent Application No. 10-2024-0135655, filed on Oct. 7, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to a bicomponent spunbond nonwoven fabric, and more particularly, to a bicomponent spunbond nonwoven fabric including a filament that uses bio-polyethylene as a sheath component.BACKGROUND

[0003] A nonwoven fabric is a versatile material widely used in various industrial fields, and is generally produced by melting a polymer material into fibers and then entangling them. A spunbond nonwoven fabric has a structure in which melt-spun fibers are directly stacked and bonded, and various physical characteristics thereof may be imparted mainly by adjusting the thickness and length of a filament. Such a spunbond nonwoven fabric is mainly made of polypropylene (PP), which offers excellent mechanical properties and processability.

[0004] However, a polypropylene nonwoven fabric often exhibits limitations in softness and bulkiness due to relatively rigid and stiff characteristics thereof. In addition, with the increasing importance of environmental protection and sustainability in recent years, there has been a growing demand for an eco-friendly nonwoven fabric made from a biomass-derived raw material.

[0005] Among them, bio-polyethylene (PE), which is derived from renewable resources such as sugarcane, provides significant environmental advantages. However, the use of bio-polyethylene raises concerns regarding deteriorated mechanical properties and poor processability of a nonwoven fabric. This is mainly due to the different physical characteristics of plant-derived materials compared to conventional petroleum-based materials.SUMMARY

[0006] The present disclosure provides a bicomponent spunbond nonwoven fabric that is soft and bulky and has excellent mechanical properties and processability by mixing polypropylene and bio-polyethylene.

[0007] A method for manufacturing a bicomponent spunbond nonwoven fabric according to an aspect of the present disclosure is a method for manufacturing a bicomponent spunbond nonwoven fabric including a sheath-core filament, wherein a core component of the filament includes polypropylene, wherein a sheath component of the filament includes bio-polyethylene, and wherein the method includes: drawing the filament; supplying hot air to the drawn filament to form a fiber web; and bonding the fiber web.

[0008] A bicomponent spunbond nonwoven fabric according to an aspect of the present disclosure is a bicomponent spunbond nonwoven fabric including a sheath-core filament, wherein a core component of the filament includes polypropylene, wherein a sheath component of the filament includes bio-polyethylene, and wherein a bonding pattern region has an area that is 9% to 25% of a total area of the nonwoven fabric.BRIEF DESCRIPTION OF DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0010] FIG. 1 is a flowchart illustrating an example of a method for manufacturing a bicomponent spunbond nonwoven fabric according to an embodiment of the present disclosure.

[0011] FIG. 2A is a captured image of a bicomponent spunbond nonwoven fabric according to an Example of the present disclosure.

[0012] FIG. 2B is a captured image of a bicomponent spunbond nonwoven fabric according to a Comparative Example.DETAILED DESCRIPTION

[0013] In describing the present disclosure, detailed descriptions of related known functions, which are obvious to those skilled in the art, will be omitted if it is determined that they unnecessarily obscure the gist of the present disclosure.

[0014] A bicomponent spunbond nonwoven fabric according to an embodiment of the present disclosure is a bicomponent spunbond nonwoven fabric including a sheath-core filament. The sheath-core filament may include polypropylene (PP) as a core component and polyethylene (PE) as a sheath component. Here, polyethylene may be bio-polyethylene derived from renewable resources. Unless otherwise stated, polyethylene described in this specification refers to the bio-polyethylene. In one example, polypropylene may be metallocene polypropylene (mPP) or Ziegler-Natta polypropylene (Z-N PP).

[0015] Polypropylene and polyethylene may have different melting points. In one example, the melting point of polypropylene may be higher than the melting point of polyethylene. In one example, the melting point of polypropylene may be higher than the melting point of polyethylene by 66 degrees C. or less. The melt index of polypropylene may be from 20 g / 10 min to 45 g / 10 min. The melt index of polyethylene may be from 17 g / 10 min to 30 g / 10 min. The melt index is measured under a condition of 230 degrees C. and a 5 kg load for polypropylene and a condition of 190 degrees C. and a 2.16 kg load for polyethylene. When describing numerical ranges in this specification, the expression “A to B” is to be understood as including not only values between A and B but also both A and B.

[0016] The weight ratio of polypropylene to polyethylene may be from 3:7 to 8:2, and particularly from 5:5 to 7.5:2.5. If the weight ratio of polyethylene decreases (i.e., if the weight ratio of polypropylene increases), formation of a sheath component may become difficult. In addition, the use amount of eco-friendly materials may decrease, which may significantly reduce the effect of reducing carbon dioxide emissions, and others. If the weight ratio of polyethylene increases (i.e., if the weight ratio of polypropylene decreases), the mechanical properties of the bicomponent spunbond nonwoven fabric may deteriorate.

[0017] The bicomponent spunbond nonwoven fabric may have a bonding pattern region. The bonding pattern region is a region in which fibers (e.g., filaments) of the bicomponent spunbond nonwoven fabric are bonded to each other, and the mechanical properties of the bicomponent spunbond nonwoven fabric may be improved through bonding between the fibers. The bonding pattern region may include a plurality of pin regions, where each pin region refers to a unit region in which the fibers are bonded.

[0018] Each pin region may have any of various shapes. In one example, the shape may be circular, oval, angular, regular, or irregular, but is not limited thereto. In one example, all of the pin regions may have the same shape. In another example, some of the pin regions may have shapes different from others, or may be tilted at different angles. However, these are merely examples, and the concept of the present disclosure is not limited thereto.

[0019] In one example, from a planar perspective, the bicomponent spunbond nonwoven fabric may have repeating patterned pin regions. In one example, the pin regions may be arranged at regular or irregular intervals in the horizontal and vertical directions. However, these are merely examples, and the concept of the present disclosure is not limited thereto.

[0020] The area of the bonding pattern region may be 9% to 25% of the total area of the bicomponent spunbond nonwoven fabric, particularly 10% to 20%, and more particularly 10% to 15%. If the area of the bonding pattern region is too small (e.g., less than 9%), the bonding strength between the fibers may be weakened, which may result in deterioration in the mechanical properties of the bicomponent spunbond nonwoven fabric. If the area of the bonding pattern region is too large (e.g., greater than 25%), the bonding strength between the fibers may become excessively strong, which may lead to deterioration in the softness and bulkiness of the nonwoven fabric. As a result, the softness and bulkiness of the bicomponent spunbond nonwoven fabric may be improved by having a small area for the bonding pattern region within the above numerical range.

[0021] The bonding pattern region may include 150 and 650 pin regions per 1 m2. In other words, the bicomponent spunbond nonwoven fabric may be bonded at 150 to 650 points per 1 m2. If the bonding pattern region has less than 150 pin regions, the area of each pin region needs to be excessively large, in order to satisfy the above-mentioned numerical range for the area of the bonding pattern region relative to the total area. This may deteriorate local softness and bulkiness in specific regions of the bicomponent spunbond nonwoven fabric (e.g., the pin regions and surrounding regions thereof), and uniformity in softness and bulkiness across the entire bicomponent spunbond nonwoven fabric may not be achieved. If the bonding pattern region has greater than 650 pin regions, the area of each pin region needs to be excessively small, in order to satisfy the above-mentioned numerical range for the area of the bonding pattern region relative to the total area. This may result in a reduced bonding strength in the pin region, thereby deteriorating the mechanical properties of the nonwoven fabric. As a result, by having a number of pin regions within the above-mentioned numerical range, the bonding pattern region may maintain the mechanical properties of the bicomponent spunbond nonwoven fabric despite a small area thereof.

[0022] The basis weight of the bicomponent spunbond nonwoven fabric may be from 5 gsm to 100 gsm. Due to the configuration of the area, shape, and arrangement of the bonding pattern region of the bicomponent spunbond nonwoven fabric as described above, the mechanical properties of the nonwoven fabric can be improved, allowing the bicomponent spunbond nonwoven fabric to exhibit excellent mechanical properties even with a low basis weight within the above-mentioned numerical range.

[0023] FIG. 1 is a flowchart illustrating an example of a method for manufacturing a bicomponent spunbond nonwoven fabric according to an embodiment of the present disclosure. Hereinafter, a method for manufacturing a bicomponent spunbond nonwoven fabric according to an embodiment of the present disclosure will be described with reference to FIG. 1.

[0024] Referring to FIG. 1, extrusion and melting of a raw material for a bicomponent spunbond nonwoven fabric may be performed (S10). The extrusion and melting may be performed in an extruder. For example, the raw material may be fed into the extruder in the form of pellets. When the raw material is fed into the extruder, a screw rotates to transport the raw material, and frictional heat generated during this process or heat from an external heater causes the raw material to melt. The molten raw material may have a uniform state throughout. Extrusion and melting of polypropylene and polyethylene may be performed in separate extruders.

[0025] The molten raw material from the extruder may be supplied to a spin beam through a spin pump. The molten polypropylene and polyethylene from the separate extruders thereof may move to the respective spin beams through separate paths. For example, the spin pump may supply the molten raw material from the extruder to the spin beam at a constant pressure and flow rate. This may help maintain a uniform and continuous flow of the raw material, allowing a consistent fiber quality to be achieved.

[0026] The raw material reaching each spin beam is spun from a nozzle via a distribution plate designed to form a sheath-core filament, thereby forming a sheath-core filament (S20). The spin beams in the spinning step may adjust the melt viscosity of polypropylene and polyethylene, thereby effectively controlling the spinning thereof. At this time, to set each of two materials to an appropriate melt viscosity, the temperatures of the spin beams for spinning polypropylene and polyethylene may be set differently. That is, the processability of polypropylene and polyethylene may be improved by adjusting the temperatures of the spin beams for spinning polypropylene and polyethylene.

[0027] In one example, the temperature of the spin beam for spinning polypropylene may be 2 to 10 degrees C. higher than the temperature of the spin beam for spinning polyethylene. For example, the temperature of the spin beam may refer to the temperature of a final die immediately before polypropylene or polyethylene is spun. In one example, the temperature of the spin beam for spinning polypropylene may be 245 degrees C. or higher, and the temperature of the spin beam for spinning polyethylene may be 240 degrees C. or higher. The melt viscosity of polypropylene and polyethylene can be individually controlled through temperature regulation of each spin beam, while maintaining an appropriate viscosity balance between the sheath and core is critical for ensuring spinnability and overall process stability.

[0028] During filament formation, polypropylene may be positioned in the interior of the filament to form a core component of the filament, while polyethylene may be positioned at the exterior of the filament to form a sheath component of the filament. In one example, quenching may be performed on the filament spun from the spin beams. For example, the spun filament may be exposed to cooled air to solidify the filament.

[0029] The spun filament may move to a fiber drawing unit (FDU) and to a diffuser, and may undergo drawing (S30). The mechanical properties of the filament may be improved through the drawing step. For example, molecules in the filament may be aligned during the drawing process, thereby improving the strength and durability of the filament. In one example, the drawing step may be performed one or more times.

[0030] The drawn filaments may be stacked to form a fiber web. In the fiber web formation step, hot air may be supplied (S40). The hot air may randomly disperse and stack the filaments, thereby forming a fiber web. By randomly and uniformly arranging the filaments within the fiber web, the softness and bulkiness of the final bicomponent spunbond nonwoven fabric may be improved. Furthermore, the hot air may entangle the filaments while dispersing them. Additionally, in one example, the hot air may melt at least some of the filaments, and the molten filaments may be bonded to each other. That is, a primary bonding process for the fiber web may be performed by entangling or bonding the filaments to each other.

[0031] The hot air may be supplied at a temperature of 170 to 260 degrees C. For example, if the temperature of the hot air is lower than 170 degrees C., the filaments may be bonded weakly and unevenly during the primary bonding process, resulting in deterioration in the mechanical properties of a final product. For example, if the temperature of the hot air is higher than 260 degrees C., the filaments may melt excessively or undergo thermal deformation, which may result in deterioration in the quality of the final product.

[0032] The hot air may be supplied at a pressure of 4 kPa to 15 kPa. For example, if the pressure of the hot air is lower than 4 kPa, the filaments may not be sufficiently dispersed, resulting in uneven placement and deterioration in the quality of the final product. If the pressure of the hot air is higher than 15 kPa, the fiber web being formed may be damaged by excessive pressure, which may result in deterioration in the quality of the final product.

[0033] A secondary bonding process may be performed on the fiber web (S50). Unless otherwise stated in this specification, “bonding” should be understood as referring to the secondary bonding process. By completing the bonding process for the fiber web, a bicomponent spunbond nonwoven fabric may be formed.

[0034] For example, the bonding process may be performed by passing the fiber web through a calender. In this process, a bonding pattern region may be formed on the fiber web, which may correspond to a bonding pattern region in the final bicomponent spunbond nonwoven fabric. In the bonding pattern region formed in the bonding process, the filaments may be bonded to each other, thereby ultimately improving the mechanical properties of the bicomponent spunbond nonwoven fabric.

[0035] For example, the bonding process may be performed at a temperature of 120 degrees C. to 150 degrees C. If the temperature of the bonding process is too low (e.g., lower than 120 degrees C.), the bicomponent spunbond nonwoven fabric may not have sufficient mechanical properties due to incomplete bonding. If the temperature of the bonding process is too high (e.g., higher than 150 degrees C.), the physical properties of the final product may be damaged due to excessive bonding, thermal deformation, and others.

[0036] The area of the bonding pattern region after the bonding process may be 9% to 25% of the total area of the bicomponent spunbond nonwoven fabric, particularly 10% to 20%, and more particularly 10% to 15%. The bonding pattern region may include from 150 to 650 pin regions per 1 m2. When the bonding pattern region satisfies the above numerical ranges, the bicomponent spunbond nonwoven fabric may have excellent mechanical properties while being soft and bulky.

[0037] In the manufacture of the bicomponent spunbond nonwoven fabric, by setting the conditions of each step from S10 to S50 as described above and combining these steps, the bicomponent spunbond nonwoven fabric may exhibit improved softness and bulkiness, while also having excellent mechanical properties. Furthermore, the processability of raw materials may be improved by adjusting the temperatures of the spin beams based on the melting point and melt viscosity.

[0038] The following describes the experimental results regarding the characteristics of bicomponent spunbond nonwoven fabrics in Example and Comparative Example.

[0039] In a bicomponent spunbond nonwoven fabric of the Example, the weight ratio of the core component (polypropylene) to the sheath component (polyethylene) was 70:30. The polypropylene used was metallocene propylene. The melting point of the metallocene propylene was 145 to 155 degrees C., the melt index was from 35 g / 10 min to 45 g / 10 min, and the density was 0.9 g / cm3. The polyethylene used was SHA7260, a plant-derived polyethylene from Braskem. The melting point of SHA7260 was 125 to 135 degrees C., the melt index was 20 g / 10 min, and the density was 0.955 g / cm3. In the manufacture of the Example, the temperature of the spin beam for spinning the polypropylene was maintained at 245 to 255 degrees C., and the temperature of the spin beam for spinning the polyethylene was maintained at 240 to 250 degrees C. After the filament drawing process, a fiber web was formed through the hot air process, and the bonding process was performed using a calender. The area of the bonding pattern region was 11% of the total area, and 270 pin regions per 1 m2 were formed. Finally, a bicomponent spunbond nonwoven fabric with 1.6 denier and a basis weight of 17 gsm was formed.

[0040] In a bicomponent spunbond nonwoven fabric of the Comparative Example, the weight ratio of the core component (polypropylene) to the sheath component (polyethylene) was 70:30. The polypropylene used was H7700, a Ziegler-Natta polypropylene from LG Chem. The polyethylene used was SHA7270, a plant-derived polyethylene from Braskem. In the manufacture of the Comparative Example, after the spinning step, a fiber web was formed using a compaction roll without supplying hot air. Subsequently, the bonding process was performed using a calendar, and the area of the bonding pattern region was 18% of the total area. Finally, a bicomponent spunbond nonwoven fabric with 1.6 denier and a basis weight of 17 gsm was formed.

[0041] To compare the softness of the Example and Comparative Example, a sensory test was performed. A total of 20 participants took part in the sensory test, of which 18 participants (90%) answered that the Example was softer and more preferred compared to the Comparative Example. Then, one participant (5%) answered that there was no difference in softness and preference between the Example and the Comparative Example, and one participant (5%) answered that the Comparative Example is preferred. This confirmed that the nonwoven fabric of the Example generally had superior softness compared to that of the Comparative Example.

[0042] Table 1 below shows the experimental results for the mechanical properties of the bicomponent spunbond nonwoven fabrics of the Example and Comparative Example. The experimental results represent the average values for five nonwoven fabric samples manufactured according to the Example and the average values for five nonwoven fabric samples manufactured according to the Comparative Example.TABLE 1MinimumTargettargetComparativePropertyvaluevalueExampleExampleMD strength2,4001,9003,5772,894(gf / in2)MD Elongation (%)90359075CD strength1,10070011931,276(gf / in2)CD Elongation (%)654514295Abrasion (Grade)32.62.772.76

[0043] To obtain the MD strength and MD elongation in Table 1, a tensile test was conducted on five nonwoven fabric samples having a length of 6±0.125 inches in the MD direction and a width of 2±0.125 inches in the CD direction. Then, to obtain the CD strength and CD elongation, a tensile test was conducted on five nonwoven fabric samples having a length of 6±0.125 inches in the CD direction and a width of 2±0.125 inches in the MD direction. Here, the MD direction refers to the machine direction in which the nonwoven fabric is manufactured, while the CD direction refers to the direction perpendicular to the MD direction. The MD strength and MD elongation respectively indicate the strength and elongation of the nonwoven fabric in the MD direction, whereas the CD strength and CD elongation respectively indicate the strength and elongation of the nonwoven fabric in the CD direction.

[0044] The tensile tests for the MD strength and MD elongation were conducted using a tester with a gauge length of 3±0.04 inches in the MD direction, with the break sensitivity set to 40%, and the samples being pulled at a speed of 12±0.4 inches / min in the MD direction. The tensile tests for the CD strength and CD elongation was conducted under the same conditions as those for the MD strength and MD elongation, except that the samples were tensile-loaded in the CD direction. At this time, setting the break sensitivity to 40% means that the load at the moment the sample breaks due to tension is measured, and the tensile test is then continuously conducted until the applied load decreases to 40% of the measured load. Then, since the accuracy of the test may be compromised if the load applied to the sample is too low or too high relative to the full-scale load measurable by a load cell, a load cell was used for the test such that the load applied under the above conditions would fall within 5% to 95% of the full-scale load.

[0045] The abrasion rating in Table 1 was determined through a Taber test. Specifically, the abrasion rating was determined based on damage to the nonwoven fabric sample or the amount of fluff generated on the sample after rubbing it with a 15 g wheel while rotating the nonwoven fabric sample 10 times. A higher abrasion rating indicates a nonwoven fabric with superior durability.

[0046] Referring to Table 1, it was confirmed that the bicomponent spunbond nonwoven fabric according to the Example satisfies not only the minimum target value but also the target value for each of the MD strength, MD elongation, CD strength, and CD elongation, and satisfies the minimum target value for the abrasion rating. In particular, it was confirmed that the Example exhibits a higher MD strength despite having a smaller area of the bonding pattern region, compared to the Comparative Example. That is, the Example has better softness than the Comparative Example (see the sensory test above), while still satisfying target values for mechanical properties, and further has a superior MD strength compared to the Comparative Example.

[0047] FIG. 2A is a captured image of the bicomponent spunbond nonwoven fabric according to the Example of the present disclosure. FIG. 2B is a captured image of the bicomponent spunbond nonwoven fabric according to the Comparative Example.

[0048] Referring to FIGS. 2A and 2B, it can be visually observed that in the Comparative Example, which was formed without hot air supply, the filaments were not effectively dispersed and were clumped together in some regions. In contrast, in the case of the Example formed with hot air supply, the filaments were uniformly dispersed across the entire region, and thus, no filament clumping was observed, unlike the Comparative Example.

[0049] The present disclosure has been described in connection with certain embodiments in this specification, but it is to be understood that various modifications and alterations may be made without departing from the spirit and scope of the present disclosure as understood by those skilled in the art to which the present disclosure pertains. Furthermore, such modifications and alterations are to be considered as falling within the scope of the claims appended to this specification.

[0050] According to the present disclosure, it is possible to improve the softness and bulkiness of a bicomponent spunbond nonwoven fabric through hot air supply. Furthermore, by adjusting the area of a bonding pattern region and the number of pins, it is possible to provide a bicomponent spunbond nonwoven fabric that has superior softness and bulkiness, while also maintaining excellent mechanical properties.

[0051] Although the present disclosure has been described in relation to some embodiments, it should be noted that there may be various modifications and changes without departing from the spirit and scope of the present disclosure, which can be understood by those skilled in the art. In addition, such modifications and changes should be construed to belong to the scope of the claims appended herein.

Claims

1. A method for manufacturing a bicomponent spunbond nonwoven fabric including a sheath-core filament,wherein a core component of the filament includes polypropylene,wherein a sheath component of the filament includes bio-polyethylene, andwherein the method comprises:drawing the filament;supplying hot air to the drawn filament to form a fiber web; andbonding the fiber web.

2. The method of claim 1, wherein the hot air has a temperature of 170 to 260 degrees C.

3. The method of claim 1, wherein the supplying the hot air is performed under a pressure of 4 kPa to 15 kPa.

4. The method of claim 1, further comprising spinning before the drawing,wherein, in the spinning, a spin beam spinning the polypropylene has a temperature of 245 degrees C. or higher, and a spin beam spinning the bio-polyethylene has a temperature of 240 degrees C. or higher.

5. The method of claim 4, wherein the spin beam for the polypropylene and the spin beam for the bio-polyethylene have a temperature difference of 2 to 10 degrees C.

6. The method of claim 1, wherein a bonding pattern region has an area that is 9% to 25% of a total area of the nonwoven fabric.

7. The method of claim 6, wherein the bonding pattern region includes 150 to 650 pin regions per 1 m2.

8. A bicomponent spunbond nonwoven fabric comprising a sheath-core filament,wherein a core component of the filament includes polypropylene,wherein a sheath component of the filament includes bio-polyethylene, andwherein a bonding pattern region has an area that is 9% to 25% of a total area of the nonwoven fabric.

9. The bicomponent spunbond nonwoven fabric of claim 8, wherein the bonding pattern region includes 150 to 650 pin regions per 1 m2.

Images