Nonwoven fabric for air filters, its manufacturing method, and articles made from the same

Abstract

A nonwoven fabric for air filters, a method for producing the same, and an article made of the same are disclosed. The nonwoven fabric for air filters comprises a core containing a high-melting-point polyester and a sheath containing a low-melting-point polyester, and has an MD compressive strength and a CD compressive strength of 8 to 25 N, each measured according to JIS P8126, independently of one another, and has irreversible bending properties.

Description

[Technical field]

[0001] The present invention relates to a nonwoven fabric for air filters, a manufacturing method thereof, and an article made from the fabric, and more particularly to a nonwoven fabric for air filters having excellent shape stability and breathability, a manufacturing method thereof, and an article made from the fabric. [Background technology]

[0002] Air filters, particularly cabin air filters for automobiles and cartridge filters for air cleaners, are used to let outside air into the vehicle when the vehicle is cooled or heated, or to filter the air circulating inside when the vehicle air cleaner is in operation. They are generally classified into electrostatic filters that filter particles, and combination filters that have additional antibacterial and deodorizing effects.

[0003] These two types of filters are distinguished by what layers they contain or whether they are electrostatically treated, but are basically constructed in the form of support - membrane - separation layer - activated carbon (not electrostatic) - support. In this case, the membrane is responsible for actually filtering particles, and the activated carbon layer is responsible for removing toxic gases. However, it goes without saying that the support is responsible for maintaining the shape of the filter material that performs the above functions, maximizing the surface area of ​​the filter, and improving the filtration efficiency by maintaining an appropriate porosity and constantly keeping the differential pressure constant, thereby extending the life of the entire filter. Therefore, it can be said that nonwoven fabric materials are representative of materials that exhibit physical properties that meet the above-mentioned objectives, while at the same time being able to offer consumers a competitive price through mass production.

[0004] Conventionally known polypropylene nonwoven fabrics or polyolefin nonwoven fabrics are inferior to polyester nonwoven fabrics in terms of shape stability and tensile strength, so polyester nonwoven fabrics are usually used in fields where shape stability and durability are required. In addition, in the case of polyester spunbond nonwoven fabrics generally manufactured by a thermal bonding method, single fibers or core-sheath type composite fibers are spun and laminated, and then thermally bonded with an embossing roller to impart strength and rigidity. Since an embossing bonding rate of 5 to 30% is usually imparted, it exhibits appropriate levels of tensile strength and elongation while also having deformation followability. However, in the case of the embossing bonding method, bonding at specific sites is excessive rather than bonding between the entire fibers constituting the nonwoven fabric, resulting in weak thermal bonding between the fibers of the entire nonwoven fabric, causing fluffing, or insufficient stiffness of the entire sheet required for specific applications, or if the thermal compression bonding rate is excessively high, it induces reduced breathability and increased differential pressure.

[0005] To improve this method, a so-called hot air through method is often adopted as a method for increasing the thermal fusion bonding between fibers, in which high-temperature hot air is passed between the fibers to thermally bond them. However, a high temperature of at least 200°C is required to thermally fuse polyester, and a large amount of hot air is also required, so in the case of bonding drum equipment used in spunbonding, a high-speed continuous nonwoven fabric production method, a fairly high level of specification and expensive equipment is used. In addition, the shape stability (i.e., stiffness) of the final product often does not meet the level required for filters.

[0006] In order to overcome this, in order to achieve the above-mentioned functions even with low-specification equipment, some low-melting point raw materials are used, in which the melting point is set to a level of less than 200°C (usually 120 to 180°C) by modifying the polyester raw materials. However, these raw materials have problems in that they require several times longer to dry than general polyester raw materials or polyester raw materials modified to have a melting point of 200°C or higher, and stable melting and extrusion during spinning are difficult, making them disadvantageous for continuous production. Summary of the Invention [Problem to be solved by the invention]

[0007] An embodiment of the present invention provides a nonwoven fabric for air filters having excellent shape stability and breathability.

[0008] Another aspect of the present invention provides a method for producing the nonwoven fabric for air filters.

[0009] Yet another aspect of the present invention provides an article comprising the nonwoven fabric for air filtering. [Means for solving the problem]

[0010] One aspect of the present invention is A core portion including a high melting point polyester; A sheath including a low melting point polyester; Including, The compressive strength in the MD direction and the compressive strength in the CD direction measured according to JIS P8126 are each independently 8 to 25N, Provided is a nonwoven fabric for air filters having irreversible bending properties.

[0011] The intrinsic viscosity (IV) of the high melting point polyester and the intrinsic viscosity (IV) of the low melting point polyester are each independently 0.640 to 0.660, the weight ratio of the high melting point polyester to the low melting point polyester is 70:30 to 90:10, the melting point of the high melting point polyester is 250 to 260°C, and the melting point of the low melting point polyester is 200 to 230°C.

[0012] The nonwoven fabric for air filters has a maximum irreversible folding height of 25 to 60 mm after folding processing.

[0013] The nonwoven fabric for air filters is also configured so that, after bending, the irreversible bending width gradually increases from the peaks to the valleys.

[0014] The nonwoven fabric for air filters also has a basis weight of 50 to 80 gsm.

[0015] The nonwoven fabric for air filters has an air permeability of 200 ccs or more and a thickness of 0.20 to 0.50 mm.

[0016] The nonwoven fabric for air filters does not have an embossed pattern on the surface, and the constituent fineness is also 10 to 15 denier.

[0017] Another aspect of the present invention is An article is provided that includes the nonwoven air filter fabric.

[0018] The article may also be a support for a mask, a support for an air filter, an air filter or an air purifier.

[0019] Yet another aspect of the present invention is A step of melting and spinning the high melting point polyester and the low melting point polyester to form a composite fiber, the high melting point polyester forming a core and the low melting point polyester forming a sheath, the step of controlling the spinning speed to 3,800 to 4,400 mpm (S10); (S20) a step of forming a nonwoven web by accumulating the composite fiber on a continuously driven porous screen belt, and controlling a driving speed of the porous screen belt so that the weight of the formed nonwoven web is 50 to 80 gsm; The present invention provides a method for producing a nonwoven fabric for an air filter, comprising the steps of:

[0020] The method for manufacturing a nonwoven fabric for an air filter may further include a step (S30) of preliminarily heat-bonding the nonwoven fabric web formed in step (S20) with a calendar roller having no pattern, and then heat-bonding the nonwoven fabric web at 180 to 240° C. using a hot air method, an embossing roll method having a heat compression rate of 5 to 15%, or a combination thereof.

[0021] The nonwoven fabric web thus accumulated is preliminarily heat-bonded using a calendar roller having no pattern, and then heat-bonded at 180 to 240°C using a hot air method, an embossing roll method having a heat compression rate of 5 to 15%, or a combination thereof (S30).

[0022] The thermal bonding step (S30) may be performed at a temperature of 180 to 240° C. using a contact type, a non-contact type, or a combination thereof. Effect of the Invention

[0023] The nonwoven fabric according to an embodiment of the present invention is manufactured by spinning a high-fiber (10 denier or more) sheath / core shape compared to conventionally used polyethylene terephthalate (PET) spunbond nonwoven fabrics and by using a non-contact thermal bonding method (e.g., air through bonding) instead of thermal bonding by embossing, thereby improving the overall thermal bonding between fibers and minimizing the area to be thermally fused, and ensuring the air permeability and shape stability required for a filter support without using an ultra-low melting point raw material with disadvantageous productivity and a high-performance air through drum. [Brief description of the drawings]

[0024] [Figure 1] 2 is a schematic view showing a folded shape of a nonwoven fabric for an air filter according to an embodiment of the present invention after folding processing; [Diagram 2] 1 is a schematic view showing a folded shape of a nonwoven fabric for air filters according to the prior art after folding processing; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, a nonwoven fabric for air filters according to an embodiment of the present invention will be described in detail.

[0026] In this specification, the term "irreversible pleating property" refers to the property that when a material is pleated using a pleating machine, the pleated shape is not deformed in the absence of external force and the material maintains the initial pleated shape.

[0027] In addition, in this specification, the term "maximum irreversible pleated height" refers to the maximum pleated height at which irreversible bending can be achieved. Therefore, if an attempt is made to bend to a height higher than the maximum irreversible pleated height, irreversible bending cannot be achieved and the initially bent shape cannot be maintained. For reference, the greater the pleated height, the more difficult it becomes to irreversibly bend.

[0028] In addition, in this specification, the term "irreversible pleated width" means the width between two opposing slopes after bending to achieve the maximum irreversible bending height.

[0029] The nonwoven fabric for air filters according to one embodiment of the present invention includes a core portion including a high melting point polyester and a sheath portion including a low melting point polyester.

[0030] The intrinsic viscosity (IV) of the high melting point polyester and the intrinsic viscosity (IV) of the low melting point polyester are each independently 0.640 to 0.660.

[0031] The weight ratio of the high melting point polyester to the low melting point polyester is also 70:30 to 90:10.

[0032] The melting point of the high melting point polyester is 250 to 260°C, and the melting point of the low melting point polyester is 200 to 230°C.

[0033] The high melting point polyester may also include polyethylene naphthalate (PEN), polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), Vectran, or combinations thereof.

[0034] The low melting point polyesters also include copolymerized polyethylene terephthalates such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(ethylene terephthalate-co-isophthalate).

[0035] The nonwoven fabric for air filters has a compressive strength in the MD direction and a compressive strength in the CD direction, each of which is independent of each other, of 8 to 25 N (Newton) as measured according to JIS P8126. If each compressive strength is less than 8 N, the outer shape of the product is easily deformed by an external force and it is difficult to maintain the original shape, which leads to a decrease in durability of the product and an increase in differential pressure, etc., whereas if it exceeds 25 N, bending is not easy and processing is difficult.

[0036] The nonwoven fabric for air filters has irreversible bending properties.

[0037] In addition, the nonwoven fabric for air filters has a maximum irreversible folding height of 25 to 60 mm after folding processing.

[0038] The nonwoven fabric for air filters is also configured so that the irreversible bending width gradually increases from the apex to the valley after bending. Specifically, the nonwoven fabric for air filters is not configured so that the irreversible bending width increases and then decreases, decreases and then increases, increases and then decreases and then increases again, or decreases and then increases and then decreases again after bending from the apex to the valley.

[0039] The basis weight of the nonwoven fabric for air filters is 50 to 80 gsm (g / m 2 ) as well.

[0040] The air permeability of the nonwoven fabric for air filters is 200ccs (cm 3 / cm 2 / sec) or more.

[0041] The nonwoven fabric for air filters has a thickness of 0.20 to 0.50 mm.

[0042] Moreover, the nonwoven fabric for air filters does not need to have an embossed pattern on the surface.

[0043] The nonwoven fabric for air filters has a component fineness of 10 to 15 denier.

[0044] Another aspect of the present invention provides an article comprising the nonwoven fabric for air filtering.

[0045] The article may also be a support for a mask, a support for an air filter, an air filter or an air purifier.

[0046] FIG. 1 is a schematic view showing a folded shape of a nonwoven fabric 10 for an air filter according to an embodiment of the present invention after folding processing.

[0047] Referring to FIG. 1, a nonwoven fabric 10 for air filters according to one embodiment of the present invention has a maximum irreversible bending height (Hm) and irreversible bending widths (dn, dn-1, dn-2, dn-3; where n is an integer of 4 or more) after bending processing.

[0048] The maximum irreversible bending height (Hm) is also 25 to 60 mm.

[0049] In addition, the irreversible bend widths (dn, dn-1, dn-2, dn-3; where n is an integer equal to or greater than 4) may increase gradually from the peak 11 to the valley 12. Specifically, the order is dn>dn-1>dn-2>dn-3.

[0050] FIG. 2 is a schematic diagram showing a folded shape of a nonwoven fabric 20 for air filters according to the prior art after folding processing.

[0051] 2, the nonwoven fabric 20 for air filters according to the prior art does not have a non-reversible bending height after bending processing. Specifically, the nonwoven fabric 20 for air filters cannot achieve a non-reversible bending height no matter how low the bending height is.

[0052] Alternatively, the nonwoven fabric 20 for air filters according to the prior art can have maximum irreversible bending heights (Hm) and irreversible bending widths (dn, dn-1, dn-2, dn-3; where n is an integer of 4 or greater).

[0053] The irreversible bend widths (dn, dn-1, dn-2, dn-3; n is an integer equal to or greater than 4) may increase and then decrease, decrease and then increase, increase and then decrease and then increase again, or decrease and then increase and then decrease again, from the peak 21 to the valley 22. For example, dn>dn-1, and dn-1<dn-2であり、dn-2> It is also dn-3.

[0054] Hereinafter, a method for manufacturing a nonwoven fabric for air filters according to an embodiment of the present invention will be described in detail.

[0055] A method for manufacturing a nonwoven fabric for an air filter according to an embodiment of the present invention includes a composite fiber forming step (S10) and a nonwoven web forming step (S20).

[0056] The composite fiber forming step (S10) is a step of melting and spinning the high melting point polyester and the low melting point polyester so that the high melting point polyester forms the core and the low melting point polyester forms the sheath, thereby forming a composite fiber.

[0057] The intrinsic viscosity (IV) of the high melting point polyester and the intrinsic viscosity (IV) of the low melting point polyester are each independently 0.640 to 0.660, the weight ratio of the high melting point polyester to the low melting point polyester is 70:30 to 90:10, the melting point of the high melting point polyester is 250 to 260°C, and the melting point of the low melting point polyester is 200 to 230°C.

[0058] In addition, in the composite fiber forming step (S10), the spinning speed is also adjusted to 3,800 to 4,400 mpm (m / min).

[0059] The nonwoven web forming step (S20) is a step of accumulating the composite fibers on a continuously driven porous screen belt to form a nonwoven web.

[0060] In addition, in the nonwoven web forming step (S20), the driving speed of the porous screen belt may be adjusted so that the weight of the formed nonwoven web is 50 to 80 gsm.

[0061] The method for producing a nonwoven fabric for an air filter further includes a thermal bonding step (S30) of pre-thermally bonding the accumulated nonwoven fabric web with a calendar roller having no pattern, and then thermally bonding the nonwoven fabric web with hot air at 180 to 240°C.

[0062] Also, the thermal bonding step (S30) may be performed through a thermal bonding method of contact type, non-contact type, or a combination thereof under a temperature condition of 180 to 240°C.

[0063] The manufacturing method of the nonwoven fabric for air filters according to one embodiment of the present invention having the above-mentioned configuration satisfies all of the manufacturing conditions of (i) a spinning speed of 3,800 to 4,400 mpm, (ii) a nonwoven web weight of 50 to 80 gsm, and (iii) thermal bonding via a non-contact or contact thermal bonding method, thereby providing a nonwoven fabric for air filters having excellent compressive strength and air permeability, irreversible bending property, and configured such that the irreversible bending width gradually increases from the peak to the valley after bending processing.

[0064] In addition, the method for producing a nonwoven fabric for air filters does not require the use of a low-melting point raw material of less than 200°C (usually 120 to 180°C), which shortens the drying time and enables stable melting and extrusion during spinning, making it advantageous for continuous production.

[0065] The present invention will be described in more detail below with reference to examples. These examples are provided to more specifically explain the present invention, but the scope of the present invention is not limited to these examples. EXAMPLES

[0066] Example 1: Production of nonwoven fabric 76 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 24 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,200 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0067] Example 2: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,300 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 65 gsm.

[0068] Example 3: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,300 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 70 gsm.

[0069] Example 4: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 3,800 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0070] Example 5: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,400 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0071] Example 6: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,300 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 50 gsm.

[0072] Example 7: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,300 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 80 gsm.

[0073] Comparative Example 1: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 3,700 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0074] Comparative Example 2: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,700 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0075] Comparative Example 3: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,500 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. Thereafter, the pre-heat-bonded filaments were additionally heat-bonded at 215° C. using an embossing roller with a heat compression rate of 40%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0076] Comparative Example 4: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,400 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 90 gsm.

[0077] Comparative Example 5: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,400 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 40 gsm.

[0078] Comparative Example 6: Production of nonwoven fabric 70 parts by weight of polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 256°C, and 30 parts by weight of poly(ethylene terephthalate-co-isophthalate) (CoPET) having an intrinsic viscosity (IV) of 0.650 dl / g and a melting point (Tm) of 220°C were respectively put into separate extruders, melted and extruded. Then, the extruded polyesters were melt-spun at a spinning speed of 4,500 mpm into a core-sheath type fiber form having a core composed of polyethylene terephthalate and a sheath composed of poly(ethylene terephthalate-co-isophthalate) through a nozzle having a plurality of circular holes to form filaments. Then, the formed filaments were randomly accumulated on a porous conveyor belt with an adjusted driving speed, and preliminary heat bonding was performed at 180°C using a calendar roller without a pattern. The pre-heat-bonded filaments were then heat-bonded at 220°C using a hot air method, and then further heat-bonded at 190°C using an embossing roller with a heat compression rate of 10%, to obtain a nonwoven fabric with a basis weight of 60 gsm.

[0079] Evaluation example The physical properties of the nonwoven fabrics produced in the above-mentioned Examples 1 to 7 and Comparative Examples 1 to 6 were measured as follows, and the results are shown in Table 1 below. (1)Basic weight: KS K 0514 (2) Thickness: Measure manually using a dial gauge and calculate the average value (4) Air permeability: JIS L 1906-A method (38 inch size, 125 Pa condition, measuring equipment FX 3300) (5) Ring crush compression strength measurement method: JIS P8126 method, test speed 10mpm, a sample of 15cm x 3cm size is cut into a ring with an inner diameter of 4.5cm, the overlapping part of the sheet is fixed with a stapler, and then the compression strength test is carried out to measure the load value when pressing the ring-shaped sheet. (6) Bend processing and evaluation: Using a bending machine (SKP 1700LBS, manufactured by Samsung Machinery), bend to various bend heights and evaluate the irreversible bendability, maximum irreversible bend height, and irreversible bend width. If the irreversible bend width gradually increases from the peak to the valley (see Figure 1), it is evaluated as "good," and if not (see Figure 2), it is evaluated as "poor."

[0080] [Table 1]

[0081] Referring to Table 1, the nonwoven fabrics produced in Examples 1 to 7 were excellent in air permeability, MD compressive strength and CD compressive strength, had low width shrinkage during sheet preparation, had irreversible bendability, and had good irreversible bend width shape after bending processing.

[0082] On the other hand, the nonwoven fabric produced in Comparative Example 1 had excellent air permeability, but it underwent frequent shrinkage in the width direction during sheet production, had low compressive strength in both the MD and CD directions, and did not have irreversible bending property.

[0083] In addition, the nonwoven fabric produced in Comparative Example 2 was excellent in air permeability, MD compressive strength and CD compressive strength, had a low width shrinkage rate during sheet preparation, and had irreversible bending properties, but after bending processing, the irreversible bending width shape was poor.

[0084] In addition, the nonwoven fabric produced in Comparative Example 3 had a low width shrinkage rate during sheet production, but had low air permeability, low MD and CD compressive strengths, and no irreversible bending property.

[0085] In addition, the nonwoven fabric produced in Comparative Example 4 was shown to have excellent compressive strength in both the MD and CD directions, and a low width shrinkage rate during sheet production, but also had low air permeability and no irreversible bending property.

[0086] In addition, the nonwoven fabric produced in Comparative Example 5 had excellent air permeability and a low width shrinkage rate during sheet production, but it also had low MD and CD compressive strengths and did not have irreversible bending properties.

[0087] In addition, the nonwoven fabric produced in Comparative Example 6 had excellent air permeability, a low width shrinkage rate during sheet production, and irreversible bending properties; however, compared with the nonwoven fabrics of Examples 1 to 7, it had a low bending height, low MD and CD compressive strengths, and was poor in irreversible bending width form after bending processing.

[0088] The present invention has been described with reference to the drawings and embodiments, but they are merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical scope of the present invention is defined by the technical ideas of the claims.

Claims

1. A core portion including a high melting point polyester; A sheath including a low melting point polyester; An article comprising a nonwoven air filter fabric formed from composite fibers formed from The nonwoven fabric for air filters is - The compressive strength in the MD direction and the compressive strength in the CD direction measured according to JIS P8126 are each independently 8 to 25 N; - has irreversible tortuosity, - the bent shape is configured such that the irreversible bend width increases progressively from the peak to the valley, The irreversible bending width shape after the bending process is shown in the following figure: 【Chemistry 1】 The article is confirmed by the fact that the irreversible bending widths (dn, dn-1, dn-2, dn-3; where n is an integer of 4 or more) shown in the following order are not deformed in the absence of application of an external force and are maintained as they are in the order of dn>dn-1>dn-2>dn-3.

2. the intrinsic viscosity (IV value) of the high melting point polyester and the intrinsic viscosity (IV value) of the low melting point polyester are each independently 0.640 to 0.660; the weight ratio of the high melting point polyester to the low melting point polyester is from 70:30 to 90:10; The melting point of the high melting point polyester is 250 to 260° C. The article of claim 1, wherein the low melting point polyester has a melting point of 200 to 230°C.

3. 2. The article of claim 1, wherein the bent configuration has a maximum irreversible bend height of 25 to 60 mm.

4. The article of claim 1, wherein the basis weight of the air filter nonwoven is from 50 to 80 gsm.

5. 2. The article according to claim 1, wherein the nonwoven fabric for air filters has an air permeability of 200 ccs or more and a thickness of 0.20 to 0.50 mm.

6. The article according to claim 1, wherein the nonwoven fabric for air filters has a component fineness of 10 to 15 denier.

7. 10. The article of claim 1, wherein the article is a support for a mask, a support for an air filter, an air filter, or an air purifier.

8. A step of melting and spinning the high melting point polyester and the low melting point polyester to form a composite fiber, the high melting point polyester forming a core and the low melting point polyester forming a sheath, the spinning speed being adjusted to 3,800 to 4,400 mpm (S10); (S20) forming a nonwoven web by accumulating the composite fibers on a continuously driven porous screen belt, and controlling the driving speed of the porous screen belt so that the weight of the formed nonwoven web is 50 to 80 gsm; The nonwoven fabric web formed in the step (S20) is preliminarily heat-bonded by a calendar roller having no pattern, and then heat-bonded at 180 to 240° C. by a hot air method, an embossing roll method having a heat compression rate of 5 to 15%, or a combination thereof, to obtain a nonwoven fabric for an air filter (S30); forming the nonwoven fabric for air filters into the folded shape; A method for producing the article according to any one of claims 1 to 7, comprising:

9. the intrinsic viscosity (IV value) of the high melting point polyester and the intrinsic viscosity (IV value) of the low melting point polyester are each independently 0.640 to 0.660; the weight ratio of the high melting point polyester to the low melting point polyester is from 70:30 to 90:10; The melting point of the high melting point polyester is 250 to 260° C. The method according to claim 8, wherein the melting point of the low melting point polyester is 200 to 230°C.

10. The method of claim 8, wherein the thermal bonding step (S30) is performed at a temperature of 180 to 240° C. through a thermal bonding method of contact type, non-contact type, or a combination of the two.

Images