Spun-bonded nonwoven fabric for filters and method of making same

Abstract

The present disclosure relates to a spunbond nonwoven fabric for a filter and a method of making the same. According to the present disclosure, provided are a spun-bonded nonwoven fabric for a filter having excellent filtration performance and a long service life, and a method for manufacturing the same.

Description

Technical Field

[0001] The present disclosure relates to a spunbond nonwoven fabric for a filter and a method for manufacturing the same. Background Art

[0002] A filter is a material or device that separates different phases from a gas or liquid by creating a pressure difference across a partition through which the gas or liquid containing different phases passes.

[0003] Generally, nonwoven fabrics are applied to filters. In particular, spunbond nonwoven fabrics are applied to various industrial fields including filters due to their high productivity and good mechanical properties.

[0004] The performance of nonwoven fabrics for filters varies depending on various factors constituting the nonwoven fabric. For example, the performance of nonwoven fabrics for filters varies depending on the thickness of the nonwoven fabric, the weight per unit area, and the fineness of the filaments constituting the nonwoven fabric.

[0005] Generally, nonwoven fabrics for filters are required to have excellent filtration performance and a long service life. However, when focusing on the filtration efficiency of nonwoven fabrics for filters, the pressure loss tends to increase, resulting in reduced air permeability or liquid permeability, which in turn often shortens the service life. Conversely, when focusing on the air permeability or liquid permeability of nonwoven fabrics for filters, the service life tends to be longer, but the filtration efficiency tends to decrease.

[0006] Therefore, there is a need to develop nonwoven fabrics for filters that exhibit excellent filtration performance while maintaining a long service life. Summary of the Invention

[0007] Technical Problem

[0008] An object of the present disclosure is to provide a spunbond nonwoven fabric for a filter having excellent filtration performance and a long service life.

[0009] Another object of the present disclosure is to provide a method for manufacturing the spunbond nonwoven fabric for a filter.

[0010] Technical Solution

[0011] According to an embodiment of the present disclosure, there is provided a spunbond nonwoven fabric for a filter, including a fiber web in which a first polyester filament having a melting point of 250 °C or higher and a second polyester filament having a melting point of 150 °C to 220 °C are melt-spun together,

[0012] wherein the first polyester filament has a fineness of 1 denier to 10 deniers and includes hollow cross-section filaments and profiled cross-section filaments,

[0013] Among them, the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 deniers or more.

[0014] According to another embodiment of the present disclosure, there is provided a method for manufacturing a spunbond nonwoven fabric for a filter, which includes the following steps:

[0015] Melt-spinning a first polyester having a melting point of 250 °C or higher to form first polyester filaments,

[0016] Melt-spinning a second polyester having a melting point of 150 °C to 220 °C to form second polyester filaments,

[0017] Forming a fiber web in which the first polyester filaments and the second polyester filaments are melt-spun together, and

[0018] Thermally treating the fiber web under pressure to form a spunbond nonwoven fabric;

[0019] Among them, the first polyester filaments have a fineness of 1 denier to 10 deniers and include hollow cross-section filaments and profiled cross-section filaments,

[0020] Among them, the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 deniers or more.

[0021] Now, the spunbond nonwoven fabric for a filter and its manufacturing method according to the embodiments of the present disclosure will be described in more detail.

[0022] Unless specifically stated in this specification, technical terms are intended to refer only to specific embodiments and are not intended to limit the scope of the present invention.

[0023] Unless the context clearly indicates otherwise, the singular forms used in this specification also include the plural forms.

[0024] It should be understood that terms such as "comprising", "including", "having", etc. are used in this specification to specify the presence of the described features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or groups thereof.

[0025] In this specification, terms including ordinal numbers such as "first" and "second" are used to distinguish one component from another component and are not intended to impose any numerical limitations. For example, within the scope of the present invention, the first component may also be referred to as the second component, and similarly, the second component may be referred to as the first component.

[0026] The term "denier" used in this specification is a fineness unit based on the mass (grams) of a single fiber per 9,000 meters. For example, 1 denier corresponds to 1 g / 9000 m, 0.11 mg / m, or 0.11 tex.

[0027] According to one embodiment of the present disclosure, there is provided a spunbond nonwoven fabric for a filter, which includes a fiber web in which a first polyester filament having a melting point of 250 °C or higher and a second polyester filament having a melting point of 150 °C to 220 °C are melt-spun together.

[0028] Wherein, the first polyester filament has a fineness of 1 denier to 10 deniers and includes hollow cross-section filaments and profiled cross-section filaments.

[0029] Wherein, the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 deniers or more.

[0030] As a result of the research by the present inventors, it has been confirmed that a spunbond nonwoven fabric satisfying the structure described in the above embodiment exhibits excellent filtration performance while maintaining appropriate air or liquid permeability, thereby providing a long service life.

[0031] In particular, since the spunbond nonwoven fabric for a filter includes filaments satisfying a specific structure, the amount of particles captured by the nonwoven fabric increases while reducing the pressure of the particles on the surface of the nonwoven fabric, thereby ensuring a long service life.

[0032] According to one embodiment of the present disclosure, a spunbond nonwoven fabric for a filter includes a fiber web in which a first polyester filament having a melting point of 250 °C or higher and a second polyester filament having a melting point of 150 °C to 220 °C are melt-spun together.

[0033] The first polyester filament has a melting point of 250 °C or higher, or 250 °C to 265 °C, or 250 °C to 260 °C, or 255 °C to 260 °C.

[0034] For example, the first polyester filament may include one or more first polyesters satisfying the above melting point range, which are selected from polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytetrafluoroethylene, and their copolymers.

[0035] The second polyester filament has a melting point that is at least 30 °C lower than the melting point of the first polyester filament. Preferably, the second polyester filament has a melting point of 150 °C to 220 °C, or 160 °C to 220 °C, or 160 °C to 210 °C, or 170 °C to 210 °C, or 180 °C to 210 °C, or 190 °C to 210 °C.

[0036] For example, the second polyester filament may include one or more second polyesters satisfying the above melting point range, which are selected from polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytetrafluoroethylene, and copolymers thereof.

[0037] The fiber web contains 70% to 95% by weight of the first polyester filaments and 5% to 30% by weight of the second polyester filaments. For example, the fiber web may contain 75% to 95% by weight of the first polyester filaments and 5% to 25% by weight of the second polyester filaments. In another example, the fiber web may contain 75% to 90% by weight of the first polyester filaments and 10% to 25% by weight of the second polyester filaments. In yet another example, the fiber web may contain 75% to 85% by weight of the first polyester filaments and 15% to 25% by weight of the second polyester filaments.

[0038] To ensure the bonding strength of the filaments in the fiber web, it is preferred that the second polyester filaments are included in an amount of more than 5% by weight, or more than 10% by weight, or more than 15% by weight.

[0039] However, if an excessive amount of the second polyester filaments is included in the fiber web, a decrease in the content of the first polyester filaments may lead to a decrease in the mechanical properties of the fiber web and a decrease in the processability of the spinning process and subsequent processes. Therefore, it is preferred that the second polyester filaments are included in an amount of 30% by weight or less, or 25% by weight or less.

[0040] According to one embodiment, the first polyester filaments include hollow cross-section filaments and profiled cross-section filaments.

[0041] The hollow cross-section filaments are filaments having a void in the central portion of their cross-section. The hollow cross-section filaments may have a hollow circular cross-section or a hollow profiled cross-section.

[0042] Preferably, the hollow cross-section filaments may have a hollowness ratio of 10% to 30%. The hollowness ratio is the percentage of the area of the inscribed circle based on the area of the circumscribed circle of the hollow cross-section.

[0043] To ensure the maintenance of the hollow structure during the filament spinning process, it is preferred that the hollowness ratio of the hollow cross-section filaments is at least 10%. However, if the hollowness ratio is too large, the mechanical properties of the filaments may deteriorate, and it may become difficult to maintain the hollow structure. Therefore, it is preferred that the hollowness ratio of the hollow cross-section filaments is 30% or less. Specifically, the hollowness ratio of the hollow cross-section filaments may be 10% to 30%, or 15% to 30%, or 15% to 25%.

[0044] The profiled cross-section filaments are filaments having a non-circular cross-section. For example, the profiled cross-section filaments may have a cross-sectional shape such as Y-shaped, W-shaped, triangular, star-shaped, cross-shaped, flat-shaped, or multi-leaf-shaped.

[0045] The hollow cross-section filaments and profiled cross-section filaments included in the first polyester filaments preferably have a fineness of from 1 denier to 10 denier, respectively. To ensure that the hollow cross-section and profiled cross-section shapes are maintained during the filament spinning process, it is preferred that the hollow cross-section filaments and profiled cross-section filaments each have a fineness of at least 1 denier. However, to prevent deterioration of spinnability and processability, such as pack leakage, it is preferred that the hollow cross-section filaments and profiled cross-section filaments each have a fineness of less than 10 denier.

[0046] Specifically, the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of at least 2 denier. More specifically, the fineness difference may be at least 2 denier, or within the range of 2 denier to 9 denier, 3 denier to 9 denier, 4 denier to 9 denier, 5 denier to 9 denier, 3 denier to 8 denier, 4 denier to 8 denier, 5 denier to 8 denier, 3 denier to 7 denier, 4 denier to 7 denier, or 5 denier to 7 denier.

[0047] To achieve excellent filtration performance and extended service life in the spunbond nonwoven fabric, it is preferred that the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of at least 2 denier, or at least 3 denier, or at least 4 denier, or at least 5 denier.

[0048] Under these fineness conditions, the hollow cross-section filaments may have a fineness greater than or less than that of the profiled cross-section filaments.

[0049] In addition, the first polyester filaments may include 30 wt% to 70 wt% of hollow cross-section filaments and 30 wt% to 70 wt% of profiled cross-section filaments. For example, the first polyester filaments may include 35 wt% to 70 wt% of hollow cross-section filaments and 30 wt% to 65 wt% of profiled cross-section filaments. In another example, the first polyester filaments may include 35 wt% to 65 wt% of hollow cross-section filaments and 35 wt% to 65 wt% of profiled cross-section filaments. In yet another example, the first polyester filaments may include 40 wt% to 65 wt% of hollow cross-section filaments and 35 wt% to 60 wt% of profiled cross-section filaments.

[0050] To achieve excellent filtration performance and extended service life of the spunbond nonwoven fabric, it is preferred that the first polyester filaments include hollow cross-section filaments and profiled cross-section filaments within the above ranges.

[0051] According to one embodiment, the second polyester filaments may be circular cross-section filaments.

[0052] Preferably, the second polyester filament may be a round cross-section filament having a fineness of 1 denier to 5 denier, or 1 denier to 4 denier, or 2 denier to 4 denier. To ensure the bonding strength of the filaments in the fiber web, the second polyester filament is required to have a fineness within the above range.

[0053] There is no particular limitation on the weight and thickness of the spunbond nonwoven fabric for the filter, and it can be adjusted within an appropriate range according to the application field.

[0054] Preferably, the spunbond nonwoven fabric for the filter may have a basis weight of 100 g / m 2 to 350 g / m 2 、or 150 g / m 2 to 350 g / m 2 、or 150 g / m 2 to 300 g / m 2 、or 200 g / m 2 to 300 g / m 2 .

[0055] In addition, the spunbond nonwoven fabric for the filter may have a thickness of 0.1 mm to 1.0 mm, or 0.2 mm to 1.0 mm, or 0.2 mm to 0.9 mm, or 0.3 mm to 0.9 mm.

[0056] According to another embodiment of the present disclosure, there is provided a method for manufacturing a spunbond nonwoven fabric for a filter, which includes the following steps:

[0057] Melt-spinning a first polyester having a melting point of 250 °C or higher to form first polyester filaments,

[0058] Melt-spinning a second polyester having a melting point of 150 °C to 220 °C to form second polyester filaments,

[0059] Forming a fiber web in which the first polyester filaments and the second polyester filaments are melt-spun together, and

[0060] Heat-treating the fiber web under pressure to form a spunbond nonwoven fabric;

[0061] wherein the first polyester filaments have a fineness of 1 denier to 10 denier and include hollow cross-section filaments and profiled cross-section filaments,

[0062] wherein the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 denier or more.

[0063] According to one embodiment, the spunbond nonwoven fabric for a filter can be manufactured by: melt-spinning a first polyester and a second polyester to form a fiber web in which the first polyester filaments and the second polyester filaments are mixed, and then heat-treating under pressure.

[0064] In the above manufacturing method, the properties of the first polyester, the first polyester filaments, the second polyester, and the second polyester filaments are the same as those described above.

[0065] According to one embodiment, the first polyester and the second polyester can be independently melted and spun through separate spinnerets to form the first polyester filaments and the second polyester filaments. Alternatively, the first polyester and the second polyester can be separately melted and spun through a single spinneret designed for composite spinning, which can control the number and shape of the discharge holes for different resins, thereby forming the first polyester filaments and the second polyester filaments.

[0066] Specifically, in the step of forming the first polyester filaments, the molten first polyester can be spun through a spinneret capable of adjusting the ratio of the hollow cross-section discharge holes to the profiled cross-section discharge holes, thereby obtaining hollow cross-section filaments and profiled cross-section filaments.

[0067] In the melt spinning process, the spinning speed and tension can be adjusted in consideration of the desired fineness of the first polyester filaments and the second polyester filaments.

[0068] The steps of forming the first polyester filaments and the second polyester filaments are preferably carried out at a spinning speed of 4000 m / min to 6000 m / min, or 4500 m / min to 6000 m / min, or 4500 m / min to 5500 m / min, respectively. To form filaments with appropriate crystallinity, the spinning speed is preferably 4000 m / min or more or 4500 m / min or more. However, if the spinning speed is too high, filament entanglement may occur during the spinning process, resulting in a decrease in the uniformity of the nonwoven fabric. Therefore, the spinning speed is preferably 6000 m / min or less or 5500 m / min or less.

[0069] The first polyester filaments and the second polyester filaments are blended to form a fiber web. The mixed-spun first polyester filaments and second polyester filaments are deposited onto a continuously moving mesh belt conveyor by conventional fiber opening methods such as electrostatic charging, the impact plate method, and the air flow diffusion method to form a fiber web. Here, the fiber web preferably contains 70% to 95% by weight of the first polyester filaments and 5% to 30% by weight of the second polyester filaments.

[0070] Subsequently, the fiber web undergoes heat treatment under pressure to form a spunbond nonwoven fabric.

[0071] This step involves thermally bonding the filaments contained in the fiber web to obtain a spunbond nonwoven fabric. For example, by passing the fiber web through heated rollers, a spunbond nonwoven fabric with appropriate smoothness and thickness is obtained. Conventional devices such as calender rollers and embossing rollers can be used in this step. The rollers are heated to a temperature capable of melting the second polyester filaments to an adhesive degree.

[0072] Beneficial effects

[0073] According to the present disclosure, there is provided a spunbond nonwoven fabric for a filter having excellent filtration performance and a long service life, and a manufacturing method thereof. Detailed implementation manners

[0074] Hereinafter, preferred embodiments are provided to better understand the present invention. However, the following embodiments are merely illustrative of the present invention and do not limit the present invention to these embodiments.

[0075] Example 1

[0076] Polyethylene terephthalate (PET; first polyester) with a melting point of 255 °C and copolyester (Co-PET; second polyester) with a melting point of 210 °C are each melted at 280 °C using a continuous extruder.

[0077] The first polyester melt is extruded through a spinneret assembly equipped with a spinneret having hollow cross-section discharge holes and profiled cross-section discharge holes to form hollow cross-section filaments (hollow ratio: 10%) and profiled cross-section filaments (Y-shaped cross-section) with a fineness specified in Table 1 below. The extruded continuous filaments are solidified using cooling air and then stretched using a high-pressure air stretching device to achieve a spinning speed of 5000 m / min, thereby obtaining the first polyester filaments. At this stage, the first polyester filaments are prepared to include 50% by weight of hollow cross-section filaments and 50% by weight of profiled cross-section filaments.

[0078] The second polyester melt is extruded through a spinneret having circular cross-section discharge holes to form second polyester filaments with a fineness of 2 denier.

[0079] The first polyester filaments and the second polyester filaments are mixed and spun at a weight ratio of 80:20 (weight %), and then deposited onto a continuously moving mesh conveyor to form a fiber web.

[0080] The fiber web is passed through calender rollers and embossing rollers maintained at 200 °C and 35 N / mm to obtain a spunbond nonwoven fabric with a basis weight of 270 g / m 2 and a thickness of 0.65 mm.

[0081] Examples 2-5 and Comparative Examples 1-4

[0082] The spunbond nonwoven fabric was manufactured in the same manner as in Example 1, except that the hollow cross-section filaments and the profiled cross-section filaments were made to have the fineness specified in Table 1 below.

[0083] [Table 1]

[0084]

[0085] Test Example

[0086] (1) Thickness of the nonwoven fabric

[0087] The thickness of the nonwoven fabric was measured in accordance with the Korean Standards Association KS K ISO9073-2:2006. The distance between the reference plate on which the nonwoven fabric specimen was placed and the parallel presser that applied a specified pressure to the nonwoven fabric was measured. For each example and comparative example, ten nonwoven fabric specimens (20 cm × 20 cm) were prepared, and the average thickness values were recorded in Table 2 below. For the thickness measurement, a ProGage thickness tester from Thwing-Albert Instrument was used.

[0088] (2) Filtration performance of the nonwoven fabric

[0089] The filtration performance of the nonwoven fabric was evaluated using a filtration medium test system (AFC-131, Topas GmbH) according to the method below.

[0090] Nonwoven fabric specimens (0.525 cm × 0.225 cm) were manufactured for each example and comparative example. An air flow velocity of 75.6 m 3 / h was applied. A2 fine test dust (0.3 - 1.0 μm) from ISO-12103-1 was used as the dust particles.

[0091] - Pressure drop (ΔPa): The initial pressure drop before and after the nonwoven fabric specimen was measured at an air flow velocity of 75.6 m 3 / h (RS K 0011).

[0092] - Collection efficiency (%): The ratio of the dust particles collected by the nonwoven fabric specimen was measured when the dust particles passed through the specimen at a concentration of 20 mg / m 3 and an air flow velocity of 75.6 m 3 / h.

[0093] - DHC (dust holding capacity): The weight of the dust particles collected by the nonwoven fabric specimen was measured when the final pressure reached 100 Pa after the dust particles passed through at a concentration of 70 mg / m 3 / h (RS K 0011) and an air flow velocity of 75.6 m 3 / h.

[0094] (3) Spinnability

[0095] Based on the following criteria, the spinnability of the nonwoven fabrics according to the examples and comparative examples was evaluated based on the occurrence of filament breakage and shedding during manufacturing and the uniformity of the fiber web.

[0096] -◎: A very small number of filament breakages and shedding occurred, and as normal filaments were continuously laminated onto the web, a very uniform nonwoven fabric was formed.

[0097] -○: A small number of filament breakages and shedding occurred, and as normal filaments were continuously laminated onto the web, a relatively uniform nonwoven fabric was formed.

[0098] -△: Many filament breakages occurred. Although the filaments were abnormal, a nonwoven fabric could be formed.

[0099] -X: A very large number of filament breakages occurred, and the filaments were abnormal, making it difficult to form a nonwoven fabric.

[0100] [Table 2]

[0101]

[0102] By referring to Table 1 and Table 2, the spunbond nonwoven fabrics of the examples exhibited excellent filtration performance, with a collection efficiency of over 81.5% and a DHC of 11.8 g / m 2 or more, while maintaining an appropriate pressure loss (ΔPa) within the range of 25 to 38, which is expected to ensure a long service life.

[0103] The spunbond nonwoven fabric of Comparative Example 1 exhibited the highest collection efficiency but had the highest pressure loss (ΔPa), indicating a short service life. The spunbond nonwoven fabric of Comparative Example 2 exhibited a pressure loss (ΔPa) similar to that of the examples but showed the lowest collection efficiency. In Comparative Example 3, it was impossible to manufacture the spunbond nonwoven fabric because of component leakage during melt spinning. The spunbond nonwoven fabric of Comparative Example 4 showed a relatively low collection efficiency and a high pressure loss (ΔPa).

[0104] As described above, although the present invention has been explained by referring to limited examples, the present invention is not limited thereto. Without departing from the technical concept of the present invention and within the equivalent scope of the claims set forth below, those skilled in the art to which the present invention pertains can make various modifications and changes.

Claims

1. A spunbond nonwoven fabric for a filter, comprising a fiber web in which a first polyester filament having a melting point of 250 °C or higher and a second polyester filament having a melting point of 150 °C to 220 °C are melt-spun together, Among them, The first polyester filament has a fineness of 1 denier to 10 deniers and includes hollow cross-section filaments and profiled cross-section filaments, wherein the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 deniers or more.

2. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The fiber web contains 70% to 95% by weight of the first polyester filament and 5% to 30% by weight of the second polyester filament.

3. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The first polyester filament includes 30% to 70% by weight of hollow cross-section filaments and 30% to 70% by weight of profiled cross-section filaments.

4. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 3 deniers to 9 deniers.

5. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The hollow cross-section filaments have a hollowness ratio of 10% to 30%, wherein the hollowness ratio is the percentage of the area of the inscribed circle based on the area of the circumscribed circle of the hollow cross-section.

6. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The profiled cross-section filaments have a cross-sectional shape of Y-shaped, W-shaped, triangular, star-shaped, cross-shaped, flat-shaped or multi-lobed.

7. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The second polyester filament is a circular cross-section filament having a fineness of 1 denier to 5 deniers.

8. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The spunbond nonwoven fabric has a basis weight of 100 g / m 2 to 350 g / m 2 of the basis weight.

9. The spunbond nonwoven fabric for a filter according to claim 1, Among them, The spunbond nonwoven fabric has a thickness of 0.1 mm to 1.0 mm.

10. A method for manufacturing the spunbond nonwoven fabric for a filter according to claim 1, comprising the following steps: Melt-spinning a first polyester having a melting point of 250 °C or higher to form a first polyester filament, Melt-spinning a second polyester having a melting point of 150 °C to 220 °C to form a second polyester filament, Forming a fiber web in which the first polyester filament and the second polyester filament are melt-spun together, and Heat-treating the fiber web under pressure to form a spunbond nonwoven fabric; wherein the first polyester filament has a fineness of 1 denier to 10 deniers and includes hollow cross-section filaments and profiled cross-section filaments, wherein the hollow cross-section filaments and the profiled cross-section filaments have a fineness difference of 2 deniers or more.

11. The method for manufacturing a spunbond nonwoven fabric for a filter according to claim 10, Among them, The steps of forming the first polyester filament and forming the second polyester filament are each carried out at a spinning speed of 4000 m / min to 6000 m / min.

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