JP7671785B2 - Nonwoven fabric for air filters, its manufacturing method, and articles made from the same - Google Patents

Description

The present invention relates to a nonwoven fabric for air filters, a manufacturing method thereof, and an article made from the fabric, and more specifically to a nonwoven fabric for air filters that has excellent shape stability and breathability, a manufacturing method thereof, and an article made from the fabric.

Air filters, especially cabin air filters for automobiles and cartridge filters for air purifiers, are materials used to let outside air into the vehicle when it is cooled or heated, or to filter the air circulating inside when the interior air cleaner is in operation. They are generally divided into electrostatic filters that filter particles, and combination filters that have added antibacterial and deodorizing effects.

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 filtration efficiency by maintaining an appropriate porosity and keeping the differential pressure constant at all times, thereby extending the life of the entire filter. Therefore, nonwoven fabric materials can be said to be representative 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.

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 manufactured by a thermal bonding method, monofilament 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, the bonding between specific parts is excessive rather than the bonding between the entire fibers constituting the nonwoven fabric, and the thermal bonding strength between the fibers of the entire nonwoven fabric is weak, resulting in the generation of fluff, or the stiffness of the entire sheet required for certain applications is insufficient, or if the thermal compression bonding rate is excessively high, it induces a decrease in breathability and an increase in differential pressure.

To improve on this method, the 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 or more 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., rigidity) of the final product often does not meet the level required for filters.

To overcome this, in order to achieve the above-mentioned functions even with low-specification equipment, some have used low-melting-point raw materials in which the melting point is set to a level below 200°C (usually 120-180°C) by modifying the polyester raw material, but these raw materials have the problem 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 is difficult, making them disadvantageous for continuous production.

One embodiment of the present invention provides a nonwoven fabric for air filters that has excellent shape stability and breathability.

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

Yet another aspect of the present invention provides an article comprising the nonwoven fabric for air filters.

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 25 N;
Provided is a nonwoven fabric for air filters having irreversible bending properties.

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

After bending, the nonwoven fabric for air filters has a maximum irreversible bending height of 25 to 60 mm.

The nonwoven fabric for air filters is also configured so that after bending, the irreversible bending width gradually increases from the peak to the valley.

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

The air permeability of the nonwoven fabric for air filters is 200 ccs or more, and the thickness is 0.20 to 0.50 mm.

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

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

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

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 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 present invention provides a method for producing a nonwoven fabric for an air filter, comprising the steps of:

The method for manufacturing the nonwoven fabric for air filters further includes a step (S30) of pre-thermally bonding the nonwoven fabric web formed in step (S20) with a calendar roller having no pattern, and then heat-bonding the web at 180 to 240°C using a hot air method, an embossing roll method with a heat compression rate of 5 to 15%, or a combination of these methods.

The method for manufacturing a nonwoven fabric for an air filter includes a step (S30) of pre-thermally bonding the accumulated nonwoven fabric web with a calendar roller having no pattern, and then heat-bonding the web at 180 to 240°C using a hot air method, an embossing roll method with a thermal compression rate of 5 to 15%, or a combination of these methods.

The thermal bonding step (S30) may be performed through a contact, non-contact, or combination of contact and non-contact thermal bonding methods under temperature conditions of 180 to 240°C.

The nonwoven fabric according to one embodiment of the present invention is spun into a sheath/core shape with a high fineness (10 denier or more) compared to the polyethylene terephthalate (PET) spunbond nonwoven fabrics that have been used and produced conventionally, and is produced using a non-contact thermal bonding method (such as air through bonding) rather than thermal bonding by embossing, thereby improving the overall thermal adhesion between the fibers and minimizing the surface area that is thermally fused, thereby ensuring the air permeability and shape stability required for a filter support without using an ultra-low melting point raw material that is disadvantageous in productivity and a high-performance air through drum.

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; 1 is a schematic view showing a folded shape of a nonwoven fabric for air filters according to the prior art after folding processing;

Below, we will explain in detail a nonwoven fabric for air filters according to one embodiment of the present invention.

In this specification, the term "irreversible pleating property" refers to the property that when pleated using a pleating machine, the pleated shape is not deformed and the initial pleated shape is maintained without being subjected to external force.

In addition, in this specification, "maximum irreversible pleated height" means 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, the irreversible bending will not be achieved and the initially bent shape will not be maintained. For reference, the greater the pleated height, the more difficult it becomes to achieve irreversible bending.

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

The nonwoven fabric for air filters according to one embodiment of the present invention comprises a core portion containing a high melting point polyester and a sheath portion containing a low melting point polyester.

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 also 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.

The high melting point polyester may 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 a combination thereof.

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

The nonwoven fabric for air filters has a compressive strength in the MD direction and the CD direction, measured according to JIS P8126, which are each independently between 8 and 25 N (Newton). If the compressive strength is less than 8 N, the product's outer shape is easily deformed by external forces and it is difficult to maintain its original shape, resulting in reduced durability and an increase in differential pressure. If the compressive strength exceeds 25 N, bending is not easy and processing is difficult.

The nonwoven fabric for air filters also has irreversible bending properties.

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

The nonwoven fabric for air filters is also configured so that, after bending, the irreversible bending width gradually increases from the apex to the valley. Specifically, the nonwoven fabric for air filters is not configured so that, after bending, 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.

The nonwoven fabric for air filters also has a basis weight of 50 to 80 gsm (g/m ² ).

The air filter nonwoven fabric has an air permeability of 200 ccs (cm ³ /cm ² /sec) or more.

The thickness of the nonwoven fabric for air filters is also 0.20 to 0.50 mm.

The nonwoven fabric for air filters may not have an embossed pattern on its surface.

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

Another aspect of the present invention provides an article comprising the nonwoven fabric for air filters.

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

Figure 1 is a schematic diagram showing the folded shape of a nonwoven fabric 10 for air filters according to one embodiment of the present invention after folding processing.

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

The maximum irreversible bending height (Hm) is 25 to 60 mm.

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.

Figure 2 is a schematic diagram showing the folded shape of nonwoven fabric 20 for air filters after folding processing according to conventional technology.

Referring to FIG. 2, the nonwoven fabric 20 for air filters according to the prior art does not have an irreversible bending height after bending processing. Specifically, the nonwoven fabric 20 for air filters cannot achieve an irreversible bending no matter how low the bending height is.

Alternatively, the nonwoven fabric 20 for air filters according to the prior art can have a maximum irreversible bending height (Hm) and an irreversible bending width (dn, dn-1, dn-2, dn-3; where n is an integer equal to or greater than 4).

The irreversible bend width (dn, dn-1, dn-2, dn-3; where 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 as it moves from the peak 21 to the valley 22. For example, dn>dn-1, dn-1<dn-2, and dn-2>dn-3.

Below, a method for manufacturing a nonwoven fabric for air filters according to one embodiment of the present invention will be described in detail.

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

The composite fiber formation step (S10) is a step of melting and spinning the high melting point polyester and the low melting point polyester to form a composite fiber, so that the high melting point polyester forms the core and the low melting point polyester forms the sheath.

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

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

The nonwoven web formation step (S20) is a step in which the composite fibers formed are accumulated on a continuously driven porous screen belt to form a nonwoven web.

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

The method for manufacturing the nonwoven fabric for air filters further includes a thermal bonding step (S30) in which the accumulated nonwoven fabric web is pre-thermally bonded using a calendar roller without a pattern, and then thermally bonded at 180 to 240°C using a hot air method.

The thermal bonding step (S30) can also be performed through a contact, non-contact, or combination of contact and non-contact thermal bonding methods under temperature conditions of 180 to 240°C.

The method for manufacturing a 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 that has excellent compressive strength and air permeability, has irreversible bending properties, and is configured such that the irreversible bending width gradually increases from the peak to the valley after bending processing.

In addition, the manufacturing method for nonwoven fabrics for air filters does not use low-melting-point raw materials below 200°C (usually 120-180°C), which shortens the drying time and allows for stable melting and extrusion during spinning, making it advantageous for continuous production.

The present invention will be described in more detail below through examples. These examples are intended to more specifically explain the present invention, but the scope of the present invention is not limited to these examples.

Example 1: Preparation 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 adjustable 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 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.

Example 2: Preparation 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 adjustable 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 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.

Example 3: Preparation 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 adjustable 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 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.

Example 4: Preparation 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 adjustable 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 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.

Example 5: Preparation 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 adjustable 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 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.

Example 6: Preparation 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 adjustable 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 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.

Example 7: Preparation 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 adjustable 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 heat-bonded at 220°C using a hot air method, and then additionally 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.

Comparative Example 1: Preparation 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 fed 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 adjustable 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 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.

Comparative Example 2: Preparation 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 fed 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 adjustable 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 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.

Comparative Example 3: Preparation 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 fed 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 adjustable 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.

Comparative Example 4: Preparation 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 fed 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 adjustable 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 heat-bonded at 220°C using a hot air method, and then additionally 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.

Comparative Example 5: Preparation 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 fed 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 adjustable 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 heat-bonded at 220°C using a hot air method, and then additionally 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.

Comparative Example 6: Preparation 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 fed 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 adjustable 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 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.

Evaluation Examples The physical properties of the nonwoven fabrics produced in the above 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 10 mpm, a sample of 15 cm x 3 cm size is cut into a ring with an inner diameter of 4.5 cm, the overlapping part of the sheet is fixed with a stapler, and then a compression strength test is carried out to measure the load value when the ring-shaped sheet is pressed. (6) Bending and evaluation: A bending machine (SKP 1700LBS (manufactured by Samsung Machinery)) is used to bend the sheet to various bending heights, and the irreversible bending property, maximum irreversible bending height, and irreversible bending width are evaluated. If the irreversible bending 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".

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

On the other hand, the nonwoven fabric produced in Comparative Example 1 had excellent air permeability, but it frequently contracted in the width direction during sheet production, had low compressive strength in both the MD and CD directions, and did not have irreversible bending properties.

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 production, and had irreversible bending properties, but after bending processing, the irreversible bending width shape was poor.

The nonwoven fabric produced in Comparative Example 3 also showed a low width shrinkage rate during sheet production, but low air permeability, low MD and CD compressive strengths, and no irreversible bending.

The nonwoven fabric produced in Comparative Example 4 was also 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 properties.

The nonwoven fabric produced in Comparative Example 5 also had excellent air permeability and low width shrinkage during sheet production, but also had low MD and CD compressive strengths and did not have irreversible bending properties.

The nonwoven fabric produced in Comparative Example 6 had excellent air permeability, low width shrinkage during sheet production, and irreversible bending properties, but compared to the nonwoven fabrics of Examples 1 to 7, it had low bending height, low MD and CD compressive strengths, and poor irreversible bending width shape after bending processing.

The present invention has been described with reference to the drawings and examples, but these are merely illustrative, and a person skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom. Therefore, the true technical scope of protection of the present invention is determined by the technical ideas of the claims.

Claims (10)

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:
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. 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. The article according to claim 1, wherein the maximum irreversible bending height of the bent shape is 25 to 60 mm. The article according to claim 1, wherein the basis weight of the nonwoven fabric for air filters is 50 to 80 gsm. The article according to claim 1, wherein the air permeability of the nonwoven fabric for air filters is 200 ccs or more and the thickness is 0.20 to 0.50 mm. The article according to claim 1, wherein the nonwoven fabric for air filters has a component fineness of 10 to 15 denier. 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. 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 step (S20) is preliminarily heat-bonded by a calendar roller without a 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);
The method for producing an article according to any one of claims 1 to 7 , further comprising a step of forming the nonwoven fabric for air filters into the folded shape. 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. The method of claim 8, wherein the thermal bonding step (S30) is performed through a thermal bonding method of contact type, non-contact type, or a combination of the two, under a temperature condition of 180 to 240°C.

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