Meltblown nonwoven fabric

Abstract

A melt-blown nonwoven fabric includes a plurality of melt-blown fibers, and each of the melt-blown fibers includes 90 to 95 parts by weight of a high-flowability polyester and 5 to 10 parts by weight of a high-flowability modified polyester. The high-flowability polyester has a melt index of 350 to 550 g / 10 min at a temperature of 230°C. The high-flowability modified polyester has a melt index of 200 to 400 g / 10 min at a temperature of 230°C. The melt-blown nonwoven fabric of the present disclosure can have high fiber distribution uniformity.

Description

Technical Field

[0001] This disclosure relates to a nonwoven fabric, and more particularly to a meltblown nonwoven fabric. Background Technology

[0002] In the textile industry, nonwoven fabrics, which can be formed without weaving, have become a focus of development. Furthermore, nonwoven fabrics are suitable for the consumer market due to their advantages such as short processing time, high output, low cost, and wide availability of raw materials. The broad definition of nonwoven fabric can be a cloth-like material formed using pressure or adhesive bonding. However, the manufacturing process for nonwoven fabrics can vary considerably, and the properties of the nonwoven fabric change accordingly.

[0003] Generally speaking, nonwoven fabrics formed by electrospinning typically have finer fibers compared to meltblown fabrics. However, due to limitations in electrospinning equipment, its production speed is slower than that of meltblown fabrics. Therefore, how to manufacture nonwoven fabrics with low fiber fineness and high fiber distribution uniformity using meltblown fabrics is currently a very important issue. Summary of the Invention

[0004] This disclosure provides a meltblown nonwoven fabric that can have low fiber fineness and high fiber distribution uniformity.

[0005] According to some embodiments disclosed herein, the meltblown nonwoven fabric comprises a plurality of meltblown fibers, and the meltblown fibers comprise 90 to 95 parts by weight of high-flow-rate polyester and 5 to 10 parts by weight of high-flow-rate modified polyester. The high-flow-rate polyester has a melt index between 350 g / 10 min and 550 g / 10 min at a temperature of 230°C. The high-flow-rate modified polyester has a melt index between 200 g / 10 min and 400 g / 10 min at a temperature of 230°C.

[0006] In some embodiments disclosed herein, the high-flowability modified polyester includes a low-melting-point polyester, and the melting point of the low-melting-point polyester is between 150°C and 155°C.

[0007] In some embodiments disclosed herein, the high-flowability modified polyester includes a low-melting-point polyester, and the melting point of the low-melting-point polyester is between 160°C and 165°C.

[0008] In some embodiments disclosed herein, the high-flowability modified polyester comprises a soft-chain polyester, and the soft-chain polyester has a structure represented by formula (1):

[0009]

[0010] In some embodiments disclosed herein, the high-flowability modified polyester comprises a soft-chain polyester, and the soft-chain polyester has a structure represented by formula (2):

[0011]

[0012] In some embodiments disclosed herein, the high-flowability modified polyester comprises a soft-chain polyester, and the soft-chain polyester has a structure represented by formula (3):

[0013]

[0014] Where x is a positive integer between 1 and 12, and y is a positive integer between 1 and 12.

[0015] In some embodiments disclosed herein, the weight-average molecular weight of the high-flowability modified polyester is between 8000 g / mole and 11000 g / mole.

[0016] In some embodiments disclosed herein, the intrinsic viscosity of the high-flowability modified polyester is between 0.9 dL / g and 1.3 dL / g.

[0017] In some embodiments disclosed herein, more than 50% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.5 μm.

[0018] In some embodiments disclosed herein, more than 75% of the meltblown fibers have a fiber diameter between 0.5 μm and 1.0 μm.

[0019] According to the above embodiments disclosed herein, since the meltblown fibers in the meltblown nonwoven fabric include a specific proportion of high-flow polyester and high-flow modified polyester, and the high-flow polyester and high-flow 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 nonwoven fabric, so that the meltblown nonwoven fabric disclosed herein can have high fiber distribution uniformity. Detailed Implementation

[0020] Several embodiments of this disclosure will be disclosed below. 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.

[0021] 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.

[0022] 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, "first element," "component," "region," "layer," or "part" as used below may also be referred to as a second element, component, region, layer, or part without departing from the teachings of this document.

[0023] This disclosure provides a meltblown nonwoven fabric comprising multiple meltblown fibers formed by a meltblown process. By adjusting the properties and proportions of the materials in the meltblown fibers, the meltblown fibers can have a low and concentrated fiber fineness, thereby overcoming the limitations of traditional meltblown processes. In this way, the meltblown fibers can be uniformly distributed in the meltblown nonwoven fabric, resulting in a meltblown nonwoven fabric with high fiber distribution uniformity.

[0024] The meltblown nonwoven fabric disclosed herein comprises multiple meltblown fibers, wherein the meltblown fibers comprise 90 to 95 parts by weight of high-flowability polyester and 5 to 10 parts by weight of high-flowability modified polyester. The high-flowability polyester and high-flowability modified polyester falling within the above-mentioned proportion range allow the polyester mixture formed by blending the high-flowability polyester and high-flowability 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 towards concentration. Furthermore, the high-flowability polyester and high-flowability modified polyester each have suitable melt indexes, enabling them to maintain 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 high-flow modified polyester disclosed herein has a melt index between 200 g / 10 min and 400 g / 10 min at a temperature of 230°C.

[0025] The meltblown fiber comprises 90 to 95 parts by weight of a high-flow-rate polyester. In some embodiments, the high-flow-rate polyester may be polybutylene terephthalate (PBT). In some embodiments, the weight-average molecular weight of the high-flow-rate polyester may be between 20,000 g / mole and 60,000 g / mole to ensure that the melt index of the high-flow-rate polyester is maintained within the above range, thereby facilitating the formation of meltblown fibers with low fiber fineness.

[0026] The meltblown fiber comprises 5 to 10 parts by weight of a high-flowability modified polyester. In some embodiments, the high-flowability modified polyester may include a low-melting-point polyester, which can improve the flowability of the polyester blend (including the high-flowability polyester and the high-flowability modified polyester) during the meltblown process. In some embodiments, the high-flowability modified polyester may include a soft-chain polyester, which can improve the molecular softness of the polyester blend during the meltblown process. Overall, the high-flowability modified polyester can improve the flowability and molecular softness of the polyester blend during the meltblown process, thereby improving the filament stretchability of the polyester blend to facilitate the formation of meltblown fibers with low fiber fineness.

[0027] 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.

[0028] For soft-chain polyesters, the segment stiffness 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 it 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.

[0029] In some embodiments, the first soft-chain polyester may have a structure represented by formula (1):

[0030]

[0031] In some embodiments, the second soft-chain polyester may have a structure represented by formula (2):

[0032]

[0033] In some embodiments, the third soft-chain polyester may have a structure represented by formula (3):

[0034]

[0035] Where x can be a positive integer between 1 and 12, and y can be a positive integer between 1 and 12.

[0036] Because of the presence of straight-chain alkyl segments in the structures represented by formulas (1) and (2), it provides good molecular flexibility for soft-chain polyesters. Because of the presence of ether groups in the structure represented by formula (3), it further enhances the flexibility of the soft-chain polyester, thereby improving the filament stretchability 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 providing good molecular flexibility.

[0037] In some embodiments, when the temperature is between 260°C and 280°C, the intrinsic viscosity of the high-flowability modified polyester can be between 0.9 dL / g and 1.3 dL / g, thereby 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 high-flowability modified polyester is greater than 1.3 dL / g, the high-flowability modified polyester will have too low flowability, 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 high-flowability modified polyester is less than 0.9 dL / g, the high-flowability modified polyester will have too high flowability, 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] In some implementations, the resulting meltblown fibers can have a low fiber fineness by adjusting the operating parameters of the meltblown and calendering processes. Specifically, the low fiber fineness can be achieved by adjusting the air temperature, air volume, fiber output, and receiving speed in the meltblown process, as well as the hot pressing temperature, linear pressure, and linear speed in the calendering process. The specific ranges of the operating parameters for the meltblown and calendering processes are shown in Table 1.

[0039] Table 1

[0040]

[0041] In the following description, the fiber diameter of the meltblown fibers in several comparative examples and embodiments of meltblown nonwoven fabrics will be measured to verify the effectiveness of this disclosure. Relevant descriptions of the meltblown nonwoven fabrics of each comparative example and embodiment are shown in Table 2.

[0042] Table 2

[0043]

[0044]

[0045] 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 high-flow modified polyester is 200g / 10min~400g / 10min.

[0046] Note 2: LTm1 represents the first low-melting-point polyester; LTm2 represents the second low-melting-point polyester.

[0047] Note 3: PBST represents the first soft chain polyester; PBAT represents the second soft chain polyester; PEAT represents the third soft chain polyester.

[0048] As shown in Table 2, the average fiber diameter of the meltblown fibers in the meltblown nonwoven fabrics of each embodiment is significantly smaller than that of the meltblown fibers in the meltblown nonwoven fabrics 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.

[0049] According to the embodiments disclosed above, since the meltblown fibers in the meltblown nonwoven fabric include a specific proportion of high-flow-rate polyester and high-flow-rate modified polyester, and each of the high-flow-rate polyester and the high-flow-rate 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 nonwoven fabric, resulting in high fiber distribution uniformity of the meltblown nonwoven fabric disclosed herein. Furthermore, adjusting the weight-average molecular weight and viscosity of the high-flow-rate modified polyester also helps to form meltblown fibers with a low and concentrated fiber fineness.

[0050] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Anyone skilled in the art may make various modifications and alterations 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 claims attached.

Claims

1. A melt-blown nonwoven fabric, characterized by, Comprising: a plurality of melt-blown fibers, the melt-blown fibers comprising: 90 to 95 parts by weight of a high flowability polyester, wherein the high flowability polyester has a melt index of 350 to 550 g / 10 min at a temperature of 230°C; and 5 to 10 parts by weight of a high flowability modified polyester, wherein the high flowability modified polyester has a melt index of 200 to 400 g / 10 min at a temperature of 230°C, the high flowability modified polyester comprising a low melting point polyester having a melting point of 150 to 155°C or 160 to 165°C, and comprising a soft chain polyester.

2. The melt-blown nonwoven fabric according to claim 1, wherein the high flowability modified polyester comprises a soft chain polyester having a structure represented by formula (1): ###0001### 3. The melt-blown nonwoven fabric according to claim 1, wherein the high flowability modified polyester comprises a soft chain polyester having a structure represented by formula (2): ###0002### 4. The melt-blown nonwoven fabric according to claim 1, wherein the high flowability modified polyester comprises a soft chain polyester having a structure represented by formula (3): ###0003### wherein x is a positive integer of 1 to 12, and y is a positive integer of 1 to 12.

5. The melt-blown nonwoven fabric according to claim 1, wherein the high flowability modified polyester has a weight average molecular weight of 8000 to 11000 g / mole.

6. The melt-blown nonwoven fabric according to claim 1, wherein the high flowability modified polyester has an intrinsic viscosity of 0.9 to 1.3 dL / g.

7. The melt-blown nonwoven fabric according to claim 1, wherein the fiber diameter of 50% or more of the number of the melt-blown fibers is 0.5 to 1.5 μm.

8. The melt-blown nonwoven fabric according to claim 1, wherein the fiber diameter of 75% or more of the number of the melt-blown fibers is 0.5 to 1.0 μm. ​

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