JP7629996B2 - Spunbond nonwoven fabric and its manufacturing method - Google Patents

Description

[Cross-reference to related applications]
This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0187594, filed December 30, 2020, and Korean Patent Application No. 10-2021-0189932, filed December 28, 2021, and all contents disclosed in the documents of the Korean patent application are incorporated herein by reference.

The present invention relates to a spunbond nonwoven fabric for carpets suitable for use as a material for automotive flooring, and a method for producing the same.

Carpets are interior floor products in homes, public institutions, hotels, restaurants, automobiles, etc., and are used for decoration, comfort, sound absorption, and walking comfort (cushioning).

Existing carpet structures consist of carpet yarn (BCF yarn (pile)), base fabric (non-woven fabric), latex and PVC (rubber, EVA, etc.).

Among these, the latex and PVC materials generate harmful fumes during the coating process on the base fabric (nonwoven fabric) made from tufted carpet yarn. The finished product belongs to the interior product group for car floors, and generates volatile harmful substances that pollute the air quality inside the car.

In other words, in the construction of the carpet, the latex coating process and the PVC layer are the layers from which the most volatile harmful substances are released. In addition, among the post-processing steps in manufacturing the carpet, there is a problem in that a large amount of harmful substances are released during the process of coating and curing the PVC layer.

As a result, air quality regulations are becoming more stringent worldwide and product development is moving away from latex and PVC materials.

However, the reality is that a product that meets air quality regulations while also having excellent functionality, such as strong pull-out properties for nonwoven fabrics, has yet to be developed.

The present invention provides a spunbond nonwoven fabric for carpets that uses a nonwoven fabric that acts as a highly functional latex layer, and that can stably fix carpet yarn to the nonwoven fabric without using latex or PVC materials, and a method for producing the same.

The present specification also aims to provide an environmentally friendly spunbond nonwoven fabric for carpets, which does not emit volatile harmful substances (fumes) by eliminating latex and PVC materials, and a manufacturing method thereof.

As used herein, in one embodiment,
The present invention relates to a fiber web formed from composite filaments having a form of split yarn, the composite filaments including 60 to 80% by weight of polyester filaments having a melting point of 250° C. or more and 20 to 40% by weight of copolymer filaments having a melting point of 170° C. or less,
The division ratio according to the following formula 1 is 50% or more,
The present invention provides a spunbond nonwoven fabric having room temperature strength of 18 kgf/5 cm or more, hot strength of 4.0 kgf/3 cm or less, and hot elongation of 80% or more, as measured by the standard test method of KS K 0521.

[Formula 1]
Split rate (%) = (number of split filaments) / (number of split filaments + number of unsplit filaments) x 100

(In formula 1,
The number of split filaments and the number of unsplit filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of 200 times (x200), and the split rate is the average value of 10 photographs.

Also, according to another embodiment, the present specification provides
60-80% by weight of polyester filaments having a melting point of 250° C. or more and 20-40% by weight of copolymer filaments having a melting point of 170° C. or less and a melt index (MI) of 15-25 g/10 min (ASTM 1238, 190° C.) are spun through a multi-segment composite spinneret and drawn to prepare composite filaments having a split yarn form;
laying up the composite filaments to form a fibrous web;
bonding the fibrous web by thermal bonding; and splitting filaments in the thermally bonded web;
The method for producing the spunbonded nonwoven fabric has a split ratio of 50% or more according to the following formula 1 after the step of splitting the filaments in the thermally bonded web:

[Formula 1]
Split rate (%) = (number of split filaments) / (number of split filaments + number of unsplit filaments) x 100

(In formula 1,
The number of split filaments and the number of unsplit filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of 200 times (x200), and the split rate is the average value of 10 photographs.

In addition, in another embodiment, the present specification provides a carpet including the spunbond nonwoven fabric.

The carpet according to the embodiment of the invention and its manufacturing method are described in detail below.

Unless otherwise expressly stated in this specification, the terminology is intended to refer merely to particular embodiments and is not intended to limit the invention.

As used herein, the singular forms include the plural forms unless the context clearly indicates to the contrary.

As used herein, the meaning of "comprise" is to embody certain properties, regions, constants, steps, operations, elements, components and/or components, and does not exclude the presence or inclusion of other certain properties, regions, constants, steps, operations, elements, components and/or groups.

In this specification, terms including ordinal numbers, such as "first" and "second," are used for the purpose of distinguishing one component from another component, and are not limited by the ordinal number. For example, within the scope of the present invention, a first component may be named a second component, and similarly, a second component may be named a first component.

The present invention is described in detail below.

According to one embodiment of the invention, it is possible to provide a spunbond nonwoven fabric that includes a fiber web formed from composite filaments having a split yarn form, the composite filaments including 60-80% by weight of polyester filaments having a melting point of 250°C or higher and 20-40% by weight of copolymer filaments having a melting point of 170°C or lower, and has room temperature strength of 18 kgf/5 cm or higher, hot strength of 4.0 kgf/3 cm or lower, and hot elongation of 80% or higher according to the standard test method of KS K 0521.

As a result of extensive research, the inventors have confirmed that when using composite fibers made of split yarns of matrix and binder materials with specific content ratios and melting points that are different from each other, it is possible to continuously manufacture carpets using nonwoven fabrics that can exhibit the functions of latex and PVC layers without performing a coating process of latex and PVC materials.

Therefore, this specification is characterized by producing a nonwoven fabric that incorporates the functionality of latex material from the existing carpet structure, providing a carpet without a latex layer.

In particular, in existing carpet layers, latex material plays a role in fixing carpet yarn (BCF yarn). However, since the latex material causes environmental problems, this specification aims to manufacture a nonwoven fabric for carpets that also plays the role of a latex layer by improving the functionality (pulling strength) of the nonwoven fabric with the carpet yarn without using a separate latex material.

Therefore, by eliminating the latex coating process during the manufacturing of the carpet, it is possible to eliminate the generation of harmful fumes and reduce VOCs (volatile organic compounds) in the finished product, making it environmentally friendly when used as an interior material for car floors.

The nonwoven fabric according to this specification is characterized as being a spunbond nonwoven fabric containing a fiber web formed from composite filaments in the form of split yarns, including 60 to 80% by weight of polyester filaments having a melting point of 250°C or higher and 20 to 40% by weight of copolymer filaments having a melting point of 170°C or lower.

Specifically, the nonwoven fabric can be formed into a split yarn by using polyester filaments having a melting point of 250°C or higher as the matrix material and copolymer filaments having a melting point of 170°C or lower as the binder material.

In this specification, the split yarn has a multi-split cross-sectional shape, which means that the two polymers are ultra-thinned by using a composite spinneret with a multi-split form in the method for producing ultrafine fibers, and the cross section inside the single yarn includes a multi-split shape, so the cross section is not limited to being circular. For example, the multi-split cross-sectional shape can include 8 to 64 split yarns, 16 to 32 split yarns, or 32 split yarns inside the single yarn.

Therefore, the nonwoven fabric can be given the functionality of a latex layer without the use of a latex material by specifying the mixture ratio of the matrix and binder material and using a composite filament containing 8 to 64 divided yarns.

In particular, the binder material melts during post-processing (tufting, heat treatment, backing and molding) of carpet manufacturing, and acts as a latex layer, providing high elongation for adhesive and molding performance.

In other words, the polymer used as the binder material melts when the backside of the tufting is heat-treated after the tufting process, and acts as an adhesive between the carpet raw yarn (BCF yarn) and the base fabric (nonwoven fabric). In addition, in the final molding process for manufacturing the carpet for automobiles, the binder polymer reaches a state just before melting in a high-temperature environment of 180 to 200°C, and plays a role in expressing a high elongation rate and making molding possible.

Here, if the binder content is 19% by weight or less, it is difficult to form the shape of the split yarn (the binder polymer is not extruded or is biased to one side due to uneven spinning pressure), and the binding force between the filaments that make up the nonwoven fabric is insufficient, making it prone to breakage during post-processing. If the shape of the split yarn is not uniform, deviations in physical properties will occur depending on the position of the nonwoven fabric, which may cause tearing and low pull-out strength during the post-processing molding process.

In addition, if the binder content is 41% by weight or more, there will be a shortage of matrix components that act as a support in the post-processing process for manufacturing carpets at temperatures above 180°C, and as a result, there will be a large amount of binder material that becomes molten at high temperatures, causing deformation (shrinkage, expansion) due to external forces, making post-processing impossible.

Furthermore, if the melting point of the binder raw material is 170°C or higher, it will not melt at the process temperature required to impart strength to the nonwoven fabric, act as an adhesive, and achieve high elongation, and therefore will not be able to function as a binder filament.

The filament may include split yarns having an average diameter of 22 to 31 μm and a fineness of 5.0 to 9.0 denier before splitting. More specifically, the split yarns may have an average diameter of 22 to 31 μm and a fineness of 5.0 to 9.0 denier before splitting. The cross section of the composite filament before splitting may be circular or spherical, divided into 8 to 64 parts.

When the cross-sectional shape of the composite filament is a circular cross-section and not in the form of split yarn, additional binder filaments must be spun and the matrix filaments and binder filaments must be mixed to form a web. In this case, mixing filaments has a limited uniformity, resulting in areas without binder filaments. The binder filaments are a factor that determines the tensile strength of the nonwoven fabric, and the tensile strength is determined depending on the presence/absence of binder filaments and the bonding state. However, in a circular cross-sectional shape, as mentioned above, areas without binder filaments are generated, which reduces the strength and elongation, and the pull-out strength may also be reduced.

Furthermore, the nonwoven fabric according to this specification may have a split ratio according to the following formula 1 of 50% or more, 54% or more, or 56% or more.

[Formula 1]
Split rate (%) = (number of split filaments) / (number of split filaments + number of unsplit filaments) x 100

(In formula 1,
The number of split filaments and the number of unsplit filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of ×200, and the split rate is the average value of 10 photographs.

The test piece of the nonwoven fabric cross section used when measuring the splitting rate can be adjusted in various ways; for example, a nonwoven fabric test piece measuring 3 mm x 3 mm can be used.

If the division ratio is less than 50%, the adhesive area of the binder polymer is low, and the binder is insufficient, which may result in reduced mechanical properties and pull-out strength of the nonwoven fabric.

The polyester filaments used as the matrix material may contain one or more polyester polymers selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, and recycled raw materials thereof.

The polyester filaments may contain a polyester polymer having an intrinsic viscosity (IV) of 0.60 to 0.90 dl/g and a melting point of 250°C or higher.

The binder material uses copolymer filaments with a melting point of 170°C or less and a melt index (MI) of 15 to 25 g/10 min (ASTM 1238, 190°C).

Specifically, the copolymer filament may be one or more selected from the group consisting of polyolefins having a melting point of 170°C or less and a MI (Melt index) of 15 to 25 g/10 min (ASTM 1238, 190°C). The polyolefin may be polyethylene or polypropylene.

In this specification, MI (Melt index) refers to the measurement value at 190°C according to ASTM 1238.

The nonwoven fabric provided by this method has excellent inter-filament adhesion, excellent fixation of carpet yarn, and can also improve elongation compared to conventional methods. Furthermore, by using the nonwoven fabric as the base fabric for a carpet, the pull-out strength of the final product can be improved, and since no latex or PVC materials that are harmful to the human body are used, an environmentally friendly material can be provided.

According to one example of the invention, the nonwoven fabric can simultaneously satisfy the physical properties of room temperature strength of 18 kgf/5 cm or more, hot strength of 4.0 kgf/3 cm or less, and hot elongation of 80% or more, as measured by the standard test method of KS K 0521. More specifically, by constructing the nonwoven fabric so that the above-mentioned split ratio is 54% or more, the strength and elongation can be further optimized. Therefore, the nonwoven fabric can have room temperature strength of 19 kgf/5 cm or more, hot strength of 3.0 kgf/3 cm or less, and hot elongation of 81% or more, as measured by the standard test method of KS K 0521.

The nonwoven fabric may be a spunbond nonwoven fabric having an apparent density of 225 to 310 g/ ^cm3 when the weight per unit area is 90 g/ ^m2 .

The spunbond of this specification can also improve the pull-out strength of carpets. Therefore, the carpet of this specification has a pull-out strength of 2.0 (kgf) or more according to the standard test method of KS K ISO 4919, and can be used as an automobile flooring material.

Meanwhile, according to another embodiment of the invention, a method for producing a spunbonded nonwoven fabric can be provided, which includes the steps of: spinning 60-80% by weight of polyester filaments having a melting point of 250°C or more and 20-40% by weight of copolymer filaments having a melting point of 170°C or less and a MI (Melt index) of 15-25g/10min (ASTM 1238, 190°C) through a composite spinneret having a multi-segment form, and drawing the filaments to produce a composite filament having a split yarn form; stacking the composite filaments to form a fiber web; bonding the fiber web by thermal bonding; and splitting the filaments into multiple filaments in the thermally bonded web.

The spunbond nonwoven fabric for carpets according to this specification is manufactured by the spunbond method, and includes a fiber web in the form of split yarns, which are formed by composite spinning of polyester filaments as a matrix and copolymer filaments as a binder having a specific melting point and MI under certain conditions.

In the spunbonding method, the polyester and copolymer are melted independently, allowing the number of extrusion holes for the different resins to be adjusted, and are spun and drawn through a single composite spinneret that spins in a multi-segment cross-sectional shape to obtain composite filaments.

The manufacturing method of the spunbond nonwoven fabric can be carried out using a continuous extruder, so that nonwoven fabric with excellent mechanical properties and splitting rate, which improves the pull-out strength of carpets, can be efficiently and continuously manufactured.

Specifically, the polyester (matrix) and copolymer (binder) are prepared, fed into a continuous extruder, heated and melted, and then spun through a multi-segment spinneret. Through this process, the filament can include split yarns with a multi-segment cross-section shape in which the inside of a single yarn is split. The multi-segment spinneret can be used by adjusting the number of capillaries to have 8 to 64 split yarns or 16 to 32 split yarns.

In addition, during the composite melt spinning, the number of capillaries in the spinneret can be adjusted so that the ratio of matrix (polyester) and binder (copolymer) is 60-80% by weight:20-40% by weight through the spinneret.

Here, the specific details regarding the composition of the polyester filaments, which are the matrix material, and the copolymer filaments, which are the binder material, are replaced with the details regarding the spunbond nonwoven fabric described above.

The spunbond can also be produced using a continuous extruder.

The step of producing the composite filament may also include a step of adjusting the fineness of the composite filament so that it has an average diameter of 22 to 31 μm and a fineness of 5.0 to 9.0 denier before the step of splitting the filament into multiple parts in the thermally bonded web.

The composite filaments spun in the above composite spinning form can be sufficiently stretched by adjusting the spinning speed using a high-pressure air stretching device, and the discharge rate and the number of capillaries in the spinneret can be adjusted to a level of 5.0 to 9.0 denier.

For example, the drawing is performed under a spinning speed condition of 3,000 m/min to 5,000 m/min. More specifically, for more sufficient drawing, the spinning speed may be 4,500 m/min to 5,000 m/min. If the spinning speed is less than 3,000 m/min, there is a problem that the nonwoven fabric shrinks during the heat bonding stage due to insufficient drawing of the filaments, and there is a problem that the cooling efficiency is also affected and insufficient cooling occurs, causing adhesion between the filaments during the drawing stage, resulting in poor drawing and fiber opening. In addition, if the spinning speed is more than 5,000 m/min, there is a problem that the filaments are cut during the drawing process, making it impossible to form the surface shape of the nonwoven fabric.

The web-forming and heat-bonding steps can be carried out by a fiber-opening method well known in the art.

In addition, the step of splitting the filaments in the heat-bonded web is performed using a water jet. That is, after composite fibers are spun from split yarns having a multi-split cross section, they are formed into a web, and then the split yarn cross section is split as it is by performing a water jet (spun lace) process.

Specifically, the filament fiber thus produced can be placed in the form of a web on a conveyor, and the apparent density of the web can be adjusted to 225 to 310 g/cm ³ .

The fiber web with the adjusted apparent density is thermally bonded using a calendar roll or hot air, and then passed through a water jet to split the filaments into a multi-split cross-sectional shape. At this time, a spunbond nonwoven fabric with a thickness of 0.31 mm to 0.40 mm can be produced by adjusting the water pressure of the water jet in stages.

For example, when a physical external force is applied to a nonwoven fabric that has undergone a thermal bonding process using a high-pressure water jet, the filaments are split while still in the form of split threads. That is, in this process, the two polymers that make up the split threads eventually break the physical bond between the polymers due to their insufficient compatibility with each other, and the filaments are split into ultra-fine threads. The pressure of the high-pressure water jet is not greatly limited, but applying pressure in multiple stages at a level of 50 to 280 bar can split the split threads into ultra-fine threads, making the web structure more complex and further improving the strength of the nonwoven fabric.

The high pressure water jet can also apply pressures in two or more stages within the pressure range. According to one embodiment of the invention, the high pressure water jet can apply a first stage pressure intensity of 50-80 bar, a second stage pressure intensity of 150-280 bar, and a third stage pressure intensity of 50-80 bar in that order. By adjusting the water pressure in stages as described above, not only can the thickness of the nonwoven fabric be adjusted, but also the cross section of the split yarns that has been split to the desired level can be maintained.

In this case, when pressure is applied using the high-pressure water jet, if pressure is applied only once instead of in multiple stages, there is a problem that stripe-shaped marks in the mechanical direction are left and unevenness in weight, thickness and division rate occurs when a single stage of high-pressure water jet is applied. In addition, the fewer the water jet processing stages, the more the water jet nozzle and water pollution level are affected.

Therefore, in the present invention, by treating the nonwoven fabric with a water jet in multiple stages, the nonwoven fabric can be divided multiple times through stages, increasing the division rate and imparting the function of uniformly rearranging the filaments as described above.

After the step of splitting the filaments in the heat-bonded web, the split rate according to the following formula 1 is 50% or more.

[Formula 1]
Split rate (%) = (number of split filaments) / (number of split filaments + number of unsplit filaments) x 100

(In formula 1,
The number of split filaments and the number of unsplit filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of ×200, and the split rate is the average value of 10 photographs.

The spunbond nonwoven fabric formed by the above method from filaments having a split yarn form with a specified ratio of matrix to binder can be used as a base fabric in carpet manufacturing.

Therefore, according to another embodiment of the invention, a carpet including the spunbond nonwoven fabric and a method for manufacturing the same can be provided.

The carpet can be produced through a tufting process and a cutting process using carpet yarn and spunbond nonwoven fabric.

In particular, the carpet manufacturing method does not require the coating process of latex and PVC layers as in the past, which not only shortens the process but also provides an environmentally friendly product as no harmful substances are generated.

Therefore, the carpet has carpet yarn fixed to one side of the nonwoven fabric and does not include a latex layer.

The carpet is also characterized in that it is obtained by including the steps of fixing carpet yarn to the nonwoven fabric on one side of the spunbond nonwoven fabric through tufting and heat treatment processes; and cutting the nonwoven fabric fixed to the carpet yarn.

In addition, between the step of fixing the carpet yarn and the cutting process, the method may further include a step of laminating a backing layer onto the nonwoven fabric fixed to the carpet yarn.

Specifically, a step is carried out on one side of the spunbond nonwoven fabric provided by the above method, in which carpet yarn is embedded in the nonwoven fabric through a tufting process, and the nonwoven fabric is fixed to the carpet yarn through heat treatment.

In this case, the step of fixing the carpet yarn to the nonwoven fabric may include a step of heat treating the back surface of the tufted nonwoven fabric after the tufting process.

The tufting, heat treatment and cutting processes are carried out using known methods and equipment, with needles used to fix the carpet yarn to one side of the nonwoven fabric. At this time, the tufting is carried out in a loop shape under a specified gauge (e.g., 64/5 gauge) condition.

The carpet yarn used in the tufting process may include BCF yarn, which is well known in the art. The carpet yarn may have aesthetic and cushioning functions and may have a predetermined fineness (e.g., 500 to 3,000 denier) and height (e.g., 3.0 to 7 mm). Through the tufting process, the carpet yarn is embedded in one side of the nonwoven fabric so that it is visible.

The lamination process of the backing layer is also carried out by a method well known in the art. Specifically, a heavy-weight web can be laminated onto the backing layer, and the heavy-weight web can be a short-fiber or long-fiber nonwoven web.

The carpet can be provided by a method including a lamination process of the backing layer, which includes the steps of: implanting carpet yarns into the nonwoven fabric on one side of the spunbond nonwoven fabric by a tufting process; fixing the carpet yarns by heat treating the tufted nonwoven fabric; laminating a backing layer; and cutting the laminated carpet.

Thus, a carpet according to this specification can be constructed without a latex layer, including a spunbond nonwoven fabric, carpet yarn, and a backing layer.

In a preferred example, the nonwoven fabric is tufted (a process of implanting yarn into the nonwoven fabric) with a loop-type polypropylene BCF (Bulky Continuous Filament) yarn of about 3000 denier (De')/150 filament (Fila.) on the surface at a gauge (a unit indicating the needle density in a tufting device, the needle spacing is expressed in inches, and the gauge determines the widthwise density of the TUFTED CARPET) of about 64/5 gauge and a stitch (a density in the longitudinal direction of the tufted carpet) of about 13/1. Next, the back side of the tufted product is heat-treated using a heat chamber at about 180°C, and a cutting process (size: 50 cm x 50 cm) is performed as the final process to provide a carpet. The method may further include laminating a high-weight long or short fiber as a backing layer to the carpet heat-treated by the method before the cutting process.

The carpet produced in this manner has high performance, with a pull-out strength (strength to pull the loop after tufting of the loop type) of approximately 2.0 kgf according to the standard test method of KS K ISO 4919, and can be applied in a variety of fields, specifically as an interior material for automotive flooring.

According to the present invention, by using a spunbond nonwoven fabric as a base fabric, which has excellent mechanical properties and can act as a latex material, the latex and PVC coating processes can be omitted, and as a result, no harmful fumes are generated, and VOCs (volatile hazardous substances) in the finished product can be reduced, providing a carpet that can be used as an interior product for the floor of an automobile, and a method for manufacturing the same.

The following describes in more detail the function and effect of the invention through specific examples of the invention. However, these examples are presented merely as examples of the invention, and do not define the scope of the invention's rights.

[Example 1]
A matrix made of polyethylene terephthalate (PET) material with a melting point of 255°C and a binder made of polyethylene material (MI: 20) with a melting point of 137°C were prepared, and then fed into a continuous extruder, heated and melted, and then composite-spun through one spinneret to produce filaments with an orange cross section divided into 32. In this case, the number of capillaries of the spinneret was adjusted so that the ratio of the matrix (polyester) and the binder (copolymer) was 70 wt%:30 wt% using the composite spinneret.

Next, the 32-part composite filament spun through the spinneret was solidified with cooling air at 15°C, and then sufficiently stretched using a high-pressure air stretching device to a spinning speed of 5,000 m/min to produce composite filament fibers with a fineness of 5.0 to 9.0 denier and an orange cross-section shape.

Next, the produced composite filament fiber was laminated in a web shape on a continuously moving metal conveyor net by a conventional fiber spreading method, and then subjected to a calendaring process using a flat roll having a flat surface to give an apparent density of 270 g/ ^cm3 .

Thereafter, the nonwoven fabric that had completed the calendering process was passed through a water jet to apply pressure to the nonwoven fabric in the order of pressure intensity: lower (low: 70 bar)-upper (high: 250 bar)-lower (low: 50 bar). The thickness of the nonwoven fabric was adjusted by adjusting the water pressure in stages to produce a final spunbond nonwoven fabric (weight per unit area 90 g/ ^m2 , thickness: 0.33 mm).

The nonwoven fabric was tufted (cut type, 64/5 gauge in inch, 13/1 stitch in inch, polypropylene carpet yarn (BCF; Bulky Continuous Filament) 1200 denier, pile yarn height 4 mm), and the back side of the tufting was heat treated at 235°C to fix the carpet yarn (BCF yarn) and manufacture a carpet. The tufted sample was used to measure the pull-out strength.

[Example 2]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the composite ratio of matrix:binder was changed to 80 wt %:20 wt %.

[Comparative Example 1]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the filament cross-sectional shape was changed to an orange shape and a circular shape instead of a split yarn.

[Comparative Example 2]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the binder material was changed to nylon 6.

[Comparative Example 3]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the composite ratio of matrix:binder was changed to 50 wt %:50 wt %.

[Comparative Example 4]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the composite ratio of matrix:binder was changed to 90 wt %:10 wt %.

[Comparative Example 5]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the spinning speed was set to 6,000 m/min.

[Comparative Example 6]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the spinning speed was set to 2,500 m/min.

[Comparative Example 7]
A spunbond nonwoven fabric and a carpet were produced in the same manner as in Example 1, except that the produced nonwoven fabric was not subjected to the three-stage pressure, but was only subjected to water punching at a water pressure of 294 bar.

[Test Example]
For each of the Examples, Reference Examples and Comparative Examples, physical properties were measured by the measuring methods for the following evaluation items, and the results are shown in Table 1.

1. Division rate (%)
The cross section of the nonwoven fabric was photographed with a microscope at a magnification of 200 times (x200), and the division ratio was calculated from 10 photographs (10ea) according to the following formula 1.

[Formula 1]
Split rate (%) = (number of split filaments) / (number of split filaments + number of unsplit filaments) x 100

(In formula 1,
The number of split filaments and the number of unsplit filaments are the numbers of split and unsplit filaments observed in a photograph of a cross section of a nonwoven fabric measuring 3 mm x 3 mm taken with a microscope at a magnification of 200x, and the split rate is the average value of 10 photographs.

2. Room temperature strength (kgf/5cm)
The room temperature strength was measured using standard test method according to KS K 0521.

Specifically, a test piece measuring 5 cm x 20 cm in width x length was clamped between a jig measuring 5 cm x 5 cm at the top and bottom using INSTRON's measuring equipment, and then measured at a tensile speed of 200 mm/min.

3. Hot strength (kgf/3 cm), hot elongation (%)
The hot strength and hot elongation were measured using standard test methods according to KS K 0521.

Specifically, a test piece measuring 3 cm x 10 cm was clamped between a jig measuring 5 cm x 5 cm on top and bottom using INSTRON's measuring equipment, and then preheated at 180°C for 3 minutes in a hot chamber and measured at a tensile speed of 200 mm/min.

4. Pull-out strength (%)
As described above, the nonwoven fabric was tufted (cut type, 64/5 gauge in inch, 13/1 stitch in inch, pile height 4 mm), and then the back side of the tufting was heat treated to fix the carpet yarn (BCF yarn) to produce a tufted sample.

The samples thus made were tufted according to the KS K ISO 4919 (Carpet - Tuft Pull-Out Strength Measurement) standard, with one pile to be measured being fixed to a measuring device. The loops on both sides adjacent to the loop to be measured were cut. Then, using an Instron measuring device, the pile to be measured was pulled in a direction perpendicular to the sample, and the peak strength value was recorded. This process was repeated five times and the average value was taken. Three samples were prepared for testing and repeatedly evaluated.

The results in Table 1 show that, compared to Comparative Examples 1 to 7, Examples 1 and 2 contain spunbond nonwoven fabric that acts as latex, and thus have a higher split ratio and are superior in room temperature strength, hot strength, and hot elongation. In addition, the Examples have an excellent pull-out strength of 2.0 (kgf) or more.

In contrast, Comparative Example 1 used a nonwoven fabric with a circular cross section and no divisions, and therefore had poor mechanical properties, particularly a poor pull-out strength of 1.2 kfg.

In addition, in Comparative Example 2, nylon was used as a binder, which meant that the latex could not function, and both the mechanical properties and pull-out strength were poor.

In the above Comparative Examples 3 and 4, the content of the matrix and binder material was outside the ranges specified in this specification, so the splitting rate was poor or no splitting occurred, the nonwoven fabric was not well formed, and it was difficult to manufacture the carpet.

As shown in Table 1, in Comparative Examples 5 and 6, the spinning speed was outside the range of the present invention, and therefore, it was not possible to produce a nonwoven fabric due to filament breakage in the drawing stage and shrinkage during thermal bonding. In Comparative Example 7, the high-pressure water jet was applied only in a single stage, and the split ratio was lower than in Examples 1 and 2, resulting in decreased strength, elongation, and pull-out strength.

Claims (13)

The fiber web comprises a composite filament having a form of a split yarn containing 60 to 80% by weight of polyester filaments having a melting point of 250° C. or more and 20 to 40% by weight of copolymer filaments having a melting point of 170° C. or less,
The split ratio of the composite filament according to the following formula 1 is 50% or more,
It has a room temperature strength of 18 kgf/5 cm or more, a hot strength of 4.0 kgf/3 cm or less, and a hot elongation of 80% or more according to the standard test method of KS K 0521,
According to the standard test method of KS K 0521, the room temperature strength was measured by clamping a test piece having a size of 5 cm x 20 cm between a jig having a size of 5 cm x 5 cm at the top and bottom using a measuring device manufactured by INSTRON, and then measuring the test piece at a tensile speed of 200 mm/min.
The hot strength and hot elongation of the spunbond nonwoven fabric according to the standard test method of KS K 0521 were measured by clamping a test piece having a size of 3 cm x 10 cm between a jig having a size of 5 cm x 5 cm on the top and bottom using a measuring device manufactured by INSTRON, preheating the test piece at 180°C for 3 minutes, and then measuring the test piece at a tensile speed of 200 mm/min using a hot chamber .
[Formula 1]
Composite filament split rate (%) = (number of split composite filaments) / (number of split composite filaments + number of unsplit composite filaments) x 100
(In formula 1,
The number of split composite filaments and the number of unsplit composite filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of 200 times (×200), and the split rate is the average value of 10 photographs. The spunbond nonwoven fabric according to claim 1, wherein the nonwoven fabric has a room temperature strength of 19 kgf/5 cm or more, a hot strength of 3.0 kgf/3 cm or less, and a hot elongation of 81% or more according to the standard test method of KS K 0521. The spunbond nonwoven fabric according to claim 1 , wherein the split ratio of the composite filaments is 54% or more. The spunbond nonwoven fabric according to claim 1, wherein the cross section of the composite filament before splitting is a circle divided into 8 to 64 parts. The spunbond nonwoven fabric according to claim 1, wherein the composite filaments have an average diameter before splitting of 22 to 31 μm and a fineness of 5.0 to 9.0 denier. The spunbond nonwoven fabric according to claim 1, wherein the polyester is at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate , and recycled raw materials thereof, and contains a polyester polymer having an intrinsic viscosity (IV) of 0.60 to 0.90 dl/g and a melting point of 250°C or higher. The spunbond nonwoven fabric according to claim 1, wherein the copolymer filaments contain at least one selected from the group consisting of polyolefins having a melting point of 170°C or less and a MI (Melt index) of 15 to 25 g/10 min (ASTM 1238, 190°C). 60-80 wt % of polyester filaments having a melting point of 250° C. or more and 20-40 wt % of copolymer filaments having a melting point of 170° C. or less and a melt index (MI) of 15-25 g/10 min (ASTM 1238, 190° C.) are spun through a multi-segment composite spinneret and drawn to prepare composite filaments having a split yarn form;
laying up the composite filaments to form a fibrous web;
The method includes the steps of: bonding the fiber web by thermal bonding; and splitting filaments in the thermally bonded web;
The step of splitting the filament is performed using a water jet,
After the step of splitting the filaments in the thermally bonded web, the split rate of the composite filaments according to the following formula 1 is 50% or more:
[Formula 1]
Composite filament split rate (%) = (number of split composite filaments) / (number of split composite filaments + number of unsplit composite filaments) x 100
(In formula 1,
The number of split composite filaments and the number of unsplit composite filaments are the numbers of split and unsplit filaments observed in a photograph of the cross section of the nonwoven fabric taken with a microscope (SEM) at a magnification of 200 times (×200), and the split rate is the average value of 10 photographs. The step of producing the composite filament comprises:
The method for producing a spunbonded nonwoven fabric according to claim 8, further comprising the step of adjusting the fineness of the composite filaments so that the composite filaments have an average diameter of 22 to 31 μm and a fineness of 5.0 to 9.0 denier prior to the step of splitting the filaments in the thermally bonded web. The method for producing a spunbonded nonwoven fabric according to claim 8, wherein the cross section of the composite filament before splitting is a circle divided into 8 to 64 parts. The method for producing a spunbond nonwoven fabric according to claim 8, wherein the stretching is carried out at a speed of 3,000 m/min to 5,000 m/min. A carpet comprising a spunbond nonwoven fabric according to any one of claims 1 to 7. The pull-out strength according to the standard test method of KS K ISO 4919 is 2.0 (kgf) or more,
The carpet of claim 12 used as a flooring material in an automobile.