Method for manufacturing melt-blown fiber membrane

Abstract

A method for manufacturing a melt-blown fiber film includes the following steps: passing a melt-blown film material between a first calender roll and a second calender roll to perform a calendering process on the melt-blown film material, wherein the melt-blown film material includes a plurality of melt-blown fibers, each of the melt-blown fibers includes a high-flowability polyester having a melt index of 350 g / 10 min to 550 g / 10 min at a temperature of 230°C and a modified polyester having a melt index of 200 g / 10 min to 400 g / 10 min at a temperature of 230°C, and each of the first calender roll and the second calender roll has a roll temperature of 100°C to 155°C. The method for manufacturing a melt-blown fiber film of the present disclosure can produce a melt-blown fiber film having both high moisture permeability and high air permeability.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a fiber membrane, and more particularly to a method for manufacturing a meltblown fiber membrane. Background Technology

[0002] In the textile industry, nonwoven fabrics have become a focus of development due to their non-woven nature. Furthermore, their advantages, such as short processing time, high output, low cost, and wide availability of raw materials, make them suitable for the consumer market. A broad definition of nonwoven fabric can be a cloth-like material formed using pressure or adhesive bonding. However, the processes for producing nonwoven fabrics can vary considerably, and the properties of the nonwoven fabric change accordingly.

[0003] Generally speaking, compared to meltblown fabrication, nonwoven fabrics formed by electrospinning typically have finer fibers and can also be called fiber membranes. However, due to limitations in electrospinning equipment, its production speed is slower than that of meltblown fabrication. Therefore, how to manufacture fiber membranes with low fiber fineness and high fiber distribution uniformity using meltblown fabrication, and how to give the fiber membranes appropriate and concentrated pore sizes, thereby enabling the fiber membranes to have both high air permeability and high moisture permeability, is currently a very important issue. Summary of the Invention

[0004] This disclosure provides a method for manufacturing a meltblown fiber membrane, which can produce a meltblown fiber membrane with both high moisture permeability and high air permeability.

[0005] According to some embodiments disclosed herein, a method for manufacturing a meltblown fiber membrane includes the following steps: passing a meltblown membrane material between a first pressing roller and a second pressing roller to perform a calendering process on the meltblown membrane material, wherein the meltblown membrane material includes multiple meltblown fibers, each meltblown fiber including a high-flow polyester and a modified polyester, the high-flow polyester having a melt index between 350 g / 10 min and 550 g / 10 min at a temperature of 230°C, the modified polyester having a melt index between 200 g / 10 min and 400 g / 10 min at a temperature of 230°C, and the respective roller temperatures of the first pressing roller and the second pressing roller being between 100°C and 155°C.

[0006] In some embodiments disclosed herein, the wheel gap between the first pressing roller and the second pressing roller is between 0.05 mm and 0.10 mm.

[0007] In some embodiments disclosed herein, the high-flow polyester is polybutylene terephthalate, and the temperatures of the first and second pressing rollers are respectively between 130°C and 155°C.

[0008] In some embodiments disclosed herein, the high-flow polyester is a thermoplastic polyester elastomer, and the respective wheel temperatures of the first and second pressing rollers are between 100°C and 115°C.

[0009] In some embodiments disclosed herein, the linear pressure of the first pressing roller and the second pressing roller is between 50 kg / cm and 70 kg / cm.

[0010] In some embodiments disclosed herein, more than 50% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.5 μm.

[0011] In some embodiments disclosed herein, more than 75% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm.

[0012] In some embodiments disclosed herein, the modified polyester comprises a soft-chain polyester, and the soft-chain polyester has monomer units represented by formula (1):

[0013]

[0014] In some embodiments disclosed herein, the modified polyester comprises a soft-chain polyester, and the soft-chain polyester has monomer units represented by formula (2):

[0015]

[0016] In some embodiments disclosed herein, the modified polyester comprises a soft-chain polyester having monomer units represented by formula (3):

[0017] Where x is a positive integer between 1 and 12, and y is a positive integer between 1 and 12.

[0018] According to the above-described embodiments of this disclosure, since the meltblown fibers in the meltblown membrane material used in this disclosure include high-flow polyester and modified polyester, and the high-flow polyester and modified polyester each have a specific range of melt index, the meltblown fibers can have a low and concentrated fiber fineness, thereby being uniformly distributed in the meltblown fiber membrane. Furthermore, by using a pressing wheel with a specific range of wheel temperature to perform a calendering process on the meltblown membrane material, the meltblown fiber membrane can have an appropriate and concentrated pore size, thereby enabling the meltblown fiber membrane to have both high moisture permeability and high air permeability. Attached Figure Description

[0019] To make the above and other objects, features, advantages and embodiments disclosed herein more apparent and understandable, the accompanying drawings are described below:

[0020] Figure 1 A perspective view is shown of a method for manufacturing a meltblown fiber film according to some embodiments of the present disclosure during the calendering process.

[0021] [Symbol Explanation]

[0022] 100: Meltblown film material

[0023] 210: First pressing roller

[0024] 220: Second pressing roller Detailed Implementation

[0025] The following describes several embodiments of this disclosure with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit this disclosure. That is, in some embodiments of this disclosure, these practical details are not essential and therefore should not be used to limit this disclosure. In addition, for the sake of simplicity in the drawings, some conventional structures and components will be shown in a simplified schematic manner. Furthermore, for the reader's convenience, the dimensions of the components in the drawings are not drawn to scale.

[0026] In this article, the structure of polymers or groups is sometimes represented by a skeleton formula. This representation may omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course, if the structural formula explicitly shows atoms or atomic groups, the representation shown by the artist shall prevail.

[0027] It should be understood that although the terms “first,” “second,” and “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, the terms “first element,” “component,” “region,” “layer,” or “part” used below may also be referred to as a second element, component, region, layer, or part without departing from the teachings of this document.

[0028] This disclosure provides a method for manufacturing a meltblown fiber membrane, which includes performing a calendering process on a meltblown membrane material comprising multiple meltblown fibers. By adjusting the properties of each material in the meltblown fibers, the meltblown fibers can have a low and concentrated fiber fineness, thereby being uniformly distributed in the meltblown fiber membrane. By adjusting the wheel temperature during the calendering process, the meltblown fiber membrane can have an appropriate and concentrated pore size, thereby possessing both high moisture permeability and high air permeability.

[0029] The method for manufacturing a meltblown fiber membrane disclosed herein includes steps S10 to S20. In step S10, a meltblown membrane material comprising multiple meltblown fibers is formed. In step S20, the meltblown membrane material is subjected to a calendering process to shape the meltblown membrane material into a meltblown fiber membrane. The above steps will be described in detail below.

[0030] First, in step S10, a meltblown film comprising multiple meltblown fibers is formed. The meltblown fibers disclosed herein comprise high-flowability polyester and modified polyester. In some embodiments, the content of high-flowability polyester may be between 90 parts by weight and 95 parts by weight, and the content of modified polyester may be between 5 parts by weight and 10 parts by weight. The high-flowability polyester and modified polyester falling within the above-mentioned proportion range allow the polyester mixture formed by mixing high-flowability polyester and modified polyester to possess both good flowability and molecular flexibility during the meltblown process, thereby facilitating a reduction in the fiber fineness of the formed meltblown fibers and allowing the fiber fineness of multiple meltblown fibers to tend to be concentrated. On the other hand, the high-flowability polyester and modified polyester each have suitable melt indexes, enabling them to each possess good flowability during the meltblown process, thereby reducing the fiber fineness of the meltblown fibers. Specifically, the temperature of the meltblown process can be between approximately 250°C and 300°C, while the high-flow polyester disclosed herein has a melt index (MI) between 350 g / 10 min and 550 g / 10 min at a temperature of 230°C, and the modified polyester disclosed herein has a melt index between 200 g / 10 min and 400 g / 10 min at a temperature of 230°C.

[0031] In some embodiments, the high-flow polyester may be polybutylene terephthalate (PBT). In other embodiments, the high-flow polyester may be a thermoplastic polyester elastomer. In some embodiments, the weight-average molecular weight of the high-flow polyester may be between 20,000 g / mole and 60,000 g / mole to ensure that the melt index of the high-flow polyester is maintained within the above range, thereby facilitating the formation of meltblown fibers with low fiber fineness.

[0032] In some embodiments, the modified polyester may include a low-melting-point polyester, which can improve the flowability of the polyester blend (including high-flow polyester and modified polyester) during the meltblown process. In some embodiments, the modified polyester may include a soft-chain polyester, which can improve the molecular softness of the polyester blend during the meltblown process. Overall, the modified polyester can improve the flowability and molecular softness of the polyester blend during the meltblown process, thereby improving the fiber drawing elongation of the polyester blend to facilitate the formation of meltblown fibers with low fiber fineness.

[0033] For low-melting-point polyesters, the melting point of the low-melting-point polyester can be adjusted according to actual needs to give the polyester mixture suitable fluidity. In some embodiments, the low-melting-point polyester can be a first low-melting-point polyester, a second low-melting-point polyester, or a combination thereof, wherein the melting point of the first low-melting-point polyester can be between 150°C and 155°C, and the melting point of the second low-melting-point polyester can be between 160°C and 165°C. In some embodiments, the weight-average molecular weight of the low-melting-point polyester can be between 8000 g / mole and 11000 g / mole to ensure that the melting point of the low-melting-point polyester is maintained within the above range.

[0034] For soft-chain polyesters, the segment stiffness of the soft-chain polyester can be adjusted according to actual needs to give the polyester mixture suitable molecular flexibility. For example, the segment length and branching of the soft-chain polyester can be adjusted to give the soft-chain polyester suitable segment stiffness. In some embodiments, the soft-chain polyester may be, for example, a derivative formed by modifying polybutylene terephthalate (PBT). In some embodiments, the soft-chain polyester may be a first soft-chain polyester, a second soft-chain polyester, a third soft-chain polyester, or any combination thereof. In some embodiments, the first soft-chain polyester may have a structure represented by formula (1): In some embodiments, the second soft-chain polyester may have a structure represented by formula (2):

[0035] In some embodiments, the third soft-chain polyester may have a structure represented by formula (3):

[0036] Where x can be a positive integer between 1 and 12, and y can be a positive integer between 1 and 12. Due to the presence of straight-chain alkane segments in the structures represented by formulas (1) and (2), it provides good molecular flexibility for the soft-chain polyester. Due to the presence of ether groups in the structure represented by formula (3), it can further enhance the flexibility of the soft-chain polyester, thereby improving the spinning elongation of the polyester blend. In some embodiments, the weight-average molecular weight of the soft-chain polyester can be between 8000 g / mole and 11000 g / mole to ensure that the soft-chain polyester has sufficiently long chain segments, thus exhibiting good molecular flexibility.

[0037] In some embodiments, when the temperature is between 260°C and 280°C, the intrinsic viscosity of the modified polyester can be between 0.9 dL / g and 1.3 dL / g, giving the polyester mixture good flowability during the meltblown process, which helps to form meltblown fibers with low fiber fineness. Specifically, if the intrinsic viscosity of the modified polyester is greater than 1.3 dL / g, the flowability of the modified polyester will be too low, insufficient to provide good filament stretching of the polyester mixture during the meltblown process, and unable to effectively reduce the fiber fineness of the meltblown fibers; if the intrinsic viscosity of the modified polyester is less than 0.9 dL / g, the flowability of the modified polyester will be too high, which is not conducive to controlling the formation of meltblown fibers. In some embodiments, based on the good flowability of the polyester mixture, the orifice diameter of the meltblown equipment can be configured to be about 0.15 mm to 0.30 mm, and the length-to-diameter ratio of the orifice can be configured to be about 20, thereby helping to form meltblown fibers with low fiber fineness.

[0038] Next, in step S20, the meltblown film is subjected to a calendering process to form a meltblown fiber film. For details, please refer to [link to relevant documentation]. Figure 1 This illustration depicts a three-dimensional schematic diagram of a method for manufacturing a meltblown fiber membrane according to some embodiments of the present disclosure during a calendering process. Specifically, the present disclosure involves passing a meltblown membrane 100 between a first pressing roller 210 and a second pressing roller 220 to perform a calendering process on the meltblown membrane 100. By adjusting the temperature of each of the first pressing roller 210 and the second pressing roller 220, the average D90 pore size of the meltblown membrane 100 (i.e., the average value of the distribution range of 90% of the pore sizes) can be controlled, so that the meltblown fiber membrane not only has a suitable pore size but also high pore size uniformity, thereby giving the meltblown fiber membrane high moisture permeability and high air permeability. In detail, the temperature of each of the first pressing roller 210 and the second pressing roller 220 is between 100°C and 155°C. If the temperature of the first pressing roller 210 and the second pressing roller 220 is less than 100°C, the calendering process temperature may not reach the melting point of the meltblown fibers in the meltblown film 100, failing to achieve the effect of tightly pressing the meltblown fibers together. This also results in an excessively large average D90 pore size in the meltblown fiber membrane, which lacks good structural strength and is not conducive to the fabrication of highly waterproof fabric structures in subsequent applications. Conversely, if the temperature of the first pressing roller 210 and the second pressing roller 220 is greater than 155°C, the meltblown fibers in the meltblown film 100 may over-melt, resulting in an excessively small average D90 pore size in the meltblown fiber membrane, which lacks high moisture permeability and high air permeability. Furthermore, the aforementioned roller temperature design of the first pressing roller 210 and the second pressing roller 220 can also solve the problem of interlayer delamination of the fiber membrane.

[0039] In some embodiments, when the high-flow polyester in the meltblown fiber is polybutylene terephthalate, the wheel temperatures of the first pressing roller 210 and the second pressing roller 220 can be between 130°C and 155°C. In other embodiments, when the high-flow polyester in the meltblown fiber is a thermoplastic polyester elastomer, the wheel temperatures of the first pressing roller 210 and the second pressing roller 220 can be between 100°C and 115°C. In other words, by adjusting the wheel temperatures of the first pressing roller 210 and the second pressing roller 220 according to the different high-flow polyester materials, meltblown fiber membranes of different materials can have suitable D90 average pore sizes, thereby enabling the meltblown fiber membranes to possess both high moisture permeability and high air permeability. Overall, this disclosure, by adjusting the wheel temperatures of the first pressing roller 210 and the second pressing roller 220, allows the D90 average pore size of the meltblown fiber membrane to fall between 2.5 micrometers and 3.5 micrometers (e.g., 2.6 micrometers or 3.4 micrometers).

[0040] In some embodiments, the D90 pore size distribution range of the meltblown fiber membrane (i.e., the distribution range of 90% of the pore sizes) can be further controlled by adjusting other operating parameters of the calendering process, resulting in high pore size uniformity and thus providing better moisture permeability and air permeability. In some embodiments, the wheel spacing between the first pressing roller 210 and the second pressing roller 220 can be between 0.05 mm and 0.10 mm, and the linear pressure of the first pressing roller 210 and the second pressing roller 220 can be between 50 kg / cm and 70 kg / cm. Overall, this disclosure, by adjusting the operating parameters of the above-mentioned calendering process, allows the D90 pore size distribution range of the meltblown fiber membrane to fall within the range of 2 micrometers to 4 micrometers.

[0041] In the following description, various tests (experimental examples) will be conducted on meltblown fiber membranes of several comparative examples and several embodiments to specifically verify the effectiveness of this disclosure. It should be understood that the materials used, their quantities and proportions, processing details, and processing procedures can be appropriately changed without departing from the scope of this disclosure. Therefore, this disclosure should not be interpreted as limiting based on the embodiments described below.

[0042] <Experimental Example 1: Fiber Diameter Test of Meltblown Fibers in Meltblown Fiber Membranes>

[0043] In this experimental example, the fiber diameter of the meltblown fibers in the meltblown fiber membranes of several comparative examples and several embodiments was measured. The relevant descriptions and measurement results of the meltblown fiber membranes of each comparative example and embodiment are shown in Table 1. The manufacturing method of the meltblown fiber membrane in each embodiment is as described above, and in each comparative example and each embodiment, the temperature of the first pressing roller and the second pressing roller is set to 150°C.

[0044] Table 1

[0045]

[0046]

[0047]

[0048] Note 1: At a temperature of 230℃, the MI value of conventional polyester is 100g / 10min; the MI value of high-flow polyester PBT is 350g / 10min~550g / 10min; and the MI value of modified polyester is 200g / 10min~400g / 10min.

[0049] Note 2: LTm1 represents the first low-melting-point polyester; LTm2 represents the second low-melting-point polyester.

[0050] Note 3: PBST represents the first soft chain polyester; PBAT represents the second soft chain polyester; PEAT represents the third soft chain polyester.

[0051] As can be seen from the measurement results in Table 1, the average fiber diameter of the meltblown fibers in the meltblown fiber membranes of each embodiment is significantly smaller than the average fiber diameter of the meltblown fibers in the meltblown fiber membranes of each comparative example. The measurement results of all embodiments show that more than 50% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.5 μm, and more than 14% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm, indicating that the meltblown fibers of each embodiment can have a low and concentrated fiber fineness. As can be seen from Examples 13-15, when a specific proportion of the second or third soft-chain polyester and the first low-melting-point polyester are combined with a high-flow-rate polyester, up to 73% or more of the meltblown fibers have a fiber diameter between 0.5 μm and 1.5 μm, and up to 53% or more of the meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm. In Example 15, it can be seen that up to 75% or more of the meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm, showing that the meltblown fibers of Examples 13-15 can have extremely low and extremely concentrated fiber fineness.

[0052] <Experimental Example 2: Testing of D90 Average Pore Size, Air Permeability, Moisture Permeability, and Thickness of Meltblown Fiber Membrane>

[0053] In this experimental example, the D90 average pore size, air permeability, moisture permeability, and thickness of the meltblown fiber membranes of Comparative Example 2 and Examples 14 and 15 in Table 1 were measured. In Examples 14 and 15, unlike in Table 1, the wheel temperatures of the first and second pressing rollers were modified to 145°C and 155°C, respectively. It should be understood that the D90 average pore size was measured using a pore size analyzer purchased from Porous Materials Inc. (PMI), the air permeability was measured using the standard method ASTM D737, and the moisture permeability was measured using the Taiwan standard method 12222L3223-2009 B-1. The measurement results are shown in Table 2.

[0054] Table 2

[0055]

[0056] As shown in Table 2, the average D90 pore size of the meltblown fiber membranes in each embodiment is less than 5 micrometers, the air permeability is greater than 0.5 cfm, and the moisture permeability is greater than 20000 g / m³. 2 ) / 24hr. Therefore, it can be seen that the meltblown fiber membrane prepared by the manufacturing method of the disclosed meltblown fiber membrane can have high air permeability and high moisture permeability. It should be understood that, as shown in other embodiments (not shown in the table), the D90 average pore size, air permeability, moisture permeability, and thickness of the meltblown fiber membrane disclosed herein can be between any two values ​​in Table 2, and will not be listed individually here.

[0057] According to the embodiments disclosed above, since the meltblown fibers in the meltblown membrane material used in this disclosure include high-flow polyester and modified polyester, and each of the high-flow polyester and modified polyester has a specific range of melt flow index, the meltblown fibers can have a low and concentrated fiber fineness, thereby being uniformly distributed in the meltblown fiber membrane. Furthermore, by using a pressing wheel with a specific range of wheel temperatures to perform a calendering process on the meltblown membrane, the meltblown fiber membrane can have an appropriate and concentrated pore size, thus enabling the meltblown fiber membrane to possess both high moisture permeability and high air permeability. In addition, by adjusting the wheel spacing and linear pressure during the calendering process, the meltblown fiber membrane can also have high pore size uniformity, thereby providing even better moisture permeability and air permeability.

[0058] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Any person skilled in the art may make various modifications and refinements without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the appended claims.

Claims

1. A method for manufacturing a meltblown fiber membrane, characterized in that, include: A meltblown film is passed between a first pressing roller and a second pressing roller to perform a calendering process on the meltblown film. The meltblown film includes multiple meltblown fibers, each of which includes a high-flow polyester and a modified polyester. The high-flow polyester has a melt index between 350 g / 10 min and 550 g / 10 min at a temperature of 230°C, and the modified polyester has a melt index between 200 g / 10 min and 400 g / 10 min at a temperature of 230°C. The temperature of one wheel of each of the first and second pressing rollers is between 100°C and 155°C, and the wheel distance between the first and second pressing rollers is between 0.05 mm and 0.10 mm.

2. The method for manufacturing meltblown fiber membrane as described in claim 1, characterized in that, The high-flow polyester is polybutylene terephthalate, and the temperature of the first and second pressing rollers is between 130°C and 155°C.

3. The method for manufacturing meltblown fiber membrane as described in claim 1, characterized in that, The high-flow polyester is a thermoplastic polyester elastomer, and the temperature of the first pressing wheel and the second pressing wheel is between 100°C and 115°C.

4. The method for manufacturing meltblown fiber membrane as described in claim 1, characterized in that, The linear pressure of the first pressing roller and the second pressing roller is between 50 kg / cm and 70 kg / cm.

5. The method for manufacturing a meltblown fiber membrane as described in claim 1, characterized in that, More than 50% of the plurality of meltblown fibers have a fiber diameter between 0.5 μm and 1.5 μm.

6. The method for manufacturing a meltblown fiber membrane as described in claim 1, characterized in that, More than 75% of the plurality of meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm.

7. The method for manufacturing a meltblown fiber membrane as described in claim 1, characterized in that, The modified polyester includes a soft-chain polyester, and the soft-chain polyester has monomer units represented by formula (1): Equation (1).

8. The method for manufacturing a meltblown fiber membrane as described in claim 1, characterized in that, The modified polyester includes a soft-chain polyester, and the soft-chain polyester has monomer units represented by formula (2): Equation (2).

9. The method for manufacturing a meltblown fiber membrane as described in claim 1, characterized in that, The modified polyester includes a soft-chain polyester, and the soft-chain polyester has a monomer unit represented by formula (3): Equation (3), Where x is a positive integer between 1 and 12, and y is a positive integer between 1 and 12.

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