KR102289604B1 - Manufacturing of air permeable- waterproof non woven fabric for shoes having good tensile strength and abrasion resistance - Google Patents

Abstract

The present invention relates to a manufacturing method of moisture-permeable waterproof nonwoven fabric for shoes with excellent abrasion resistance and tensile strength, which comprises the following steps: forming a meltblown web consisting of a composite fiber in which a core part is formed of a polypropylene resin and a sheath part is formed of a polyethylene resin; applying a polyolefin-based hot-melt resin to the meltblown web; and thermally bonding the hot melt resin-coated meltblown web through a heat calendar method. According to the invention, provided is a nonwoven fabric for shoes which maintains excellent moisture permeability in spite of being a meltblown nonwoven fabric, and has an excellent physical properties such as tensile and wear strength and waterproof performance.

Description

Manufacturing method of moisture-permeable waterproof nonwoven fabric for shoes with excellent abrasion and tensile strength {MANUFACTURING OF AIR PERMEABLE- WATERPROOF NON WOVEN FABRIC FOR SHOES HAVING GOOD TENSILE STRENGTH AND ABRASION RESISTANCE}

The present invention relates to a method for manufacturing a nonwoven fabric for footwear, and more particularly, to a method for manufacturing a moisture-permeable waterproof nonwoven fabric for shoes that maintains excellent moisture permeability and has excellent physical properties such as tensile and abrasion strength and waterproof performance.

In general, high-performance, high-performance moisture-permeable waterproof products are used to satisfy the harsh conditions of use used in footwear products. In particular, high-performance shoes use a moisture-permeable film made of Teflon material such as Gore-Tex to achieve moisture permeability and waterproofness at the same time.

Although the waterproof performance of these materials is excellent, the high price is burdensome, and the high tensile strength and abrasion performance required for footwear are insufficient.

In addition, the film film made of a fine porous layer of 0.2 μm or less is easily clogged during long-term use under the harsh environment of footwear, and acts as a major cause of lowering moisture permeability.

In order to solve these problems, a method of artificially making a fine porous film similar to a membrane film by foaming a polyurethane resin and coating it on a high-strength fabric or non-woven fabric is also proposed. As related prior art, there are Korean Patent Application Laid-Open No. 10-2007-0042600 and Korean Patent Application Laid-Open No. 10-2013-0127565.

However, although this method can produce a moisture-permeable waterproof layer that is relatively inexpensive and has excellent abrasion strength, it is also made of a fine porous membrane of 1.0 μm or less, so that the pores are easily clogged during long-term use, the ventilation performance is reduced, and the polyurethane resin It is difficult to use in large quantities because of environmental pollutants such as dioxins, which are generated in large amounts during incineration and disposal of materials.

Korean Patent Publication No. 10-2007-0042600 Korean Patent Publication No. 10-2013-0127565

It is an object of the present invention to provide a method of manufacturing a moisture-permeable waterproof non-woven fabric for shoes that maintains excellent moisture permeability despite being a melt-blown non-woven fabric and has excellent properties such as tensile and abrasion strength and waterproof performance.

The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be able

The present invention for achieving the above object comprises the steps of: forming a meltblown web consisting of a composite fiber in which the core part is formed of a polypropylene resin and the sheath part is formed of a polyethylene resin; applying a polyolefin-based hot melt resin to the melt blown web; and calendering thermal bonding of the meltblown web coated with the hot melt resin.

Specifically, the composite fiber may have a diameter of 1.0㎛ ~ 5.0㎛.

When the hot melt resin is applied, the ambient temperature may be maintained higher than the melting temperature of the hot melt resin.

The pores between the composite fibers of the melt blown web coated with the calender thermally bonded hot melt resin may be 0.5 μm to 5.0 μm.

According to the present invention, there is provided a nonwoven fabric for footwear that maintains excellent moisture permeability despite being a meltblown nonwoven fabric and has excellent properties such as tensile and abrasion strength and waterproof performance.

In addition, it is simple to manufacture without using an expensive fluorine material such as Teflon, so the price is low, and environmental pollution that may occur during disposal can be greatly reduced.

1 is a view showing a cross-section of a composite fiber in the manufacturing method of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Detailed descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

In the nonwoven fabric of the present invention, the core part 1 is formed of polypropylene resin and the sheath part 2 is formed of a polyethylene resin. It is manufactured including the step of applying and calendering thermal bonding of the meltblown web coated with the hot melt resin.

The meltblown web has a bulky structure of microfiber fibers. For this reason, when the microfiber meltblown web is calendered, the thickness of the web is reduced and the size of the micropores is reduced, the waterproofness required for footwear is realized, and the breathable performance (moisture permeability) is superior to that of the conventional film membrane. can be manufactured.

That is, when the meltblown web is calendered to make the thickness low, the spacing between fibers constituting the nonwoven fabric is reduced, and the size of micropores is decreased, resulting in waterproof performance. The reduced micropore size of the meltblown web coated with the final calendered hot melt resin has a distribution of 0.5 to 5.0 μm, and has a higher pore size than that of a conventional film film having micropores less than 0.2 to 1.0 μm. The nonwoven fabric of the present invention as described above has somewhat poor waterproof performance compared to the conventional film membrane, but its moisture permeability is greatly improved.

This improved moisture permeability withstands contamination from long-term use. Therefore, it can provide useful performance when used for a long time in a harsh environment such as shoes. All of the materials constituting the nonwoven fabric of the present invention are polyolefin (PO)-based resins, and there is no need to worry about deterioration of waterproof performance because properties such as wetting of the material do not appear even during long-term use.

It can have moisture permeability and waterproof performance just by making a meltblown web with a single material and calendering the web to decrease the thickness, but it lacks physical properties such as tensile strength and abrasion strength that can be used for a long time in harsh environments such as shoes.

That is, the nonwoven fabric composed of microfibers of 1.0 μm or more has very low fiber strength due to its inherent characteristics, so it is difficult to satisfy the harsh conditions required for footwear because of its low tensile strength and abrasion strength.

The present invention improves physical properties such as tensile strength and abrasion strength by improving the bonding force between fibers rather than the strength of the fibers themselves. That is, when the bonding force between the fibers is improved, the tensile strength and abrasion strength of the nonwoven fabric can be improved.

Therefore, the present invention improves the tensile strength and abrasion strength of the nonwoven fabric by forming a composite fiber using two or more components instead of a single component when spinning and manufacturing fibers from a nozzle in a melt blown method. In the present invention, a composite fiber is formed using a polyolefin-based polypropylene resin and a polyethylene resin.

By the melt blown method, the molten polypropylene resin and polyethylene resin are extruded into a large amount of composite fiber by a molding machine, blown in high-speed and high-temperature air during extrusion, and the composite fiber is collected on a running belt by hot air, so that drawing and At the same time, the composite fibers are bonded to form a porous meltblown web.

By the sheath and core or side by side method, the molten polypropylene resin and the polyethylene resin pass through the nozzle of the molding machine, and as shown in FIG. 1, the polypropylene resin is the core part. Forming (1), a polyethylene resin having a lower melting point than the polypropylene resin forms a sheath portion (2) as an outer surface to become a composite fiber.

The polyethylene resin constituting the sheath portion 2 is a low-melting polymer and has a melting point of about 80° C. to 135° C., and the composite fiber has a diameter of 1.0 μm to 5.0 μm. Polypropylene resin and polyethylene resin are materials with excellent flowability with an MFR (melt flow index) of 500 or more, and microfiber composite fibers can be formed.

The meltblown web made of microfiber composite fibers having a thickness of 1.0 to 5.0 μm is easily compressed, melted and adhered when a pressing force is applied at the same time as the temperature is raised in a calender.

In addition, the present invention applies a polyolefin-based hot melt resin to the melt blown web to have tensile strength and abrasion strength suitable for use in footwear. In other words, it realizes high tensile strength and abrasion strength required for footwear.

Conventionally, in order to improve the tensile strength and abrasion strength of the nonwoven fabric, methods of increasing the tensile and abrasion strength through crosslinking of the adhesive after infiltrating a water-soluble adhesive into the nonwoven fabric, removing moisture through drying, are used. In this case, the adhesive used is a material such as polyvinyl alcohol (PVA), polyurethane (PU), various acrylic resins or biodegradable starch.

However, when using such materials, there is a disadvantage that complex devices and high energy consumption are separately required because a process of impregnating the nonwoven fabric and a drying process after impregnation are necessarily involved.

In addition, since the fibers constituting the nonwoven fabric and other materials of the adhesive component are often introduced into the nonwoven fabric, problems such as pollution may be additionally observed when incinerated and discarded after use.

The present invention improves the physical performance of the nonwoven fabric by applying the same series of materials as the material forming the composite fibers constituting the meltblown web, and also minimizes environmental pollution that may appear when discarded after use. The coating method is preferably a hot melt spraying method, and is performed before calendering.

That is, after forming a meltblown web composed of composite fibers as described above, a polyolefin (PO)-based hot melt resin on one or both surfaces of the nonwoven fabric is sprayed onto the meltblown web at a level of 5 to 20wt%, and then calendered. When thermal bonding is performed using , the nonwoven fabric of the present invention, which is suitable for use in footwear as well as tensile strength as well as abrasion strength, is completed.

Specifically, after melting a polyolefin-based hot melt resin having a low melting temperature of 60 to 100 ° C, such as low density polyethylene (LDPE), high density polyethylene (HDPE), and atactic polypropylene (A-PP), at a high temperature of 200 ° C or higher, 0.5 It is applied uniformly by spraying it on the meltblown web at a high pressure of Kg/cm2 or more.

At this time, in order to improve the uniform coating performance, the ambient temperature is maintained above the melting temperature of the hot melt resin so that the sprayed hot melt resin can smoothly move and flow between the inside of the melt blown web and between the composite fibers. The ambient temperature is most preferably 60 to 100°C, which is the same as the melting temperature of the hot melt resin.

For example, by enclosing the periphery of the hot melt resin application with a housing and supplying hot air to the inside of the housing or generating internal heat using a heating wire, etc. to maintain a temperature above the melting temperature of the hot melt resin, the movement of the hot melt resin and flow can be maintained.

At this time, the melting temperature of the hot melt resin must be maintained lower than the melting temperature of the composite fibers constituting the melt blown web. That is, it should be kept lower than the melting temperature of the polyethylene resin forming the sheath (2). When the ambient temperature rises below the melting temperature of the polyethylene resin, the hot melt resin is easily liquefied before the sheath portion 2 of the composite fiber, so that it can easily penetrate into the interior of the composite fiber and be uniformly applied.

As such, the hot melt resin penetrating between the composite fibers can easily melt even at low temperatures during calendering, which is a subsequent process, to thermally bond between the composite fibers, make the thickness of the nonwoven fabric low, and can be easily used for shoes with a simple calendering process. This excellent finished product can be manufactured.

The meltblown web coated with hot melt resin is calendered by heating and pressing while passing between a pair of rollers, and a roll with a flat surface is used. The calender can use a two-roll system so that adhesion of the nonwoven fabric can be made smoothly and easily, and the lower end uses a heated roll made of steel and the upper end uses a soft paper roll (paper roll). roll) can be used. It is preferable that the surface temperature of the heating rolls is 80 to 120° C., and the linear pressure between the rolls is 20 to 40 Kg/cm.

Therefore, all surfaces of the meltblown web coated with the hot melt resin are heat-bonded evenly and uniformly, so that the nonwoven fabric of the present invention having excellent performance that can be used for footwear is manufactured.

If the embossing unevenness is formed on the surface of the calender roll, a nonwoven fabric having an uneven shape in the same shape as that of the embossing roll is manufactured on the surface of the nonwoven fabric. It appears alternately on the surface of the nonwoven fabric in the same way as the pattern on the surface. Then, the strength is lowered, and the water permeability is not improved, which is unsuitable.

<Production Example 1>

A polypropylene resin having a melt flow index (MFR) of 1,200 and a polyethylene resin having a melt flow index (MFR) of 600 are prepared. Two types of materials are melted at a spinning temperature of 280℃, and then spun through a nozzle with a diameter of 0.23mm and a density of 22/10mm pores. At this time, the temperature of the stretching air to be used is 310°C, and the supply pressure is 0.6 Kg/cm 2 .

The supply amount of polypropylene resin and polyethylene resin was the same at 50 wt %, and a composite fiber in the form of a sheath & core was formed to prepare a meltblown web. At this time, a polyethylene resin was formed on the surface (sheath) of the composite fiber, and a polypropylene resin was formed on the inside (core) of the composite fiber. The distance between the nozzle and the collector was 76 mm, and the fiber diameter of the prepared composite fiber was 1.2 to 4.5 μm.

In addition, the moving speed of the collector was adjusted so that the weight of the meltblown web collected in the collector was 54 gr/m 2 . Then, the hot melt resin was sprayed on both surfaces of the continuously moving melt blown web while adjusting the application amount to 10 wt % using a hot melt coating device. The hot melt resin used at this time is a polypropylene resin (propylene 70% by weight, maleic anhydride 25% by weight, ethylene 5% by weight).

On the other hand, the spraying device was uniformly applied using the Alta slot, a hot melt spray application equipment of Nordson, USA, and the melting point of the copolymerized polypropylene resin was 106 ° C. It was 160,000 cps. In addition, while maintaining the ambient temperature at 70 ℃, the hot melt resin was made easy to penetrate into the inside of the melt blown web.

Next, the meltblown web coated with the hot melt resin was passed through a calender and thermally bonded to prepare a finished nonwoven fabric. The calender used a 2-roll system, a heated roll made of steel was used for the lower part, and a paper roll made of a soft material was used for the upper part. The surface temperature of the heating rolls was 80°C, and the linear pressure between the rolls was 20 Kg/cm.

<Production Example 2>

It was prepared in the same manner as in Preparation Example 1, but the application amount of the hot melt resin was adjusted to 5 wt%.

<Production Example 3>

It was prepared in the same manner as in Preparation Example 1, but the amount of hot melt resin applied was adjusted to 20 wt%.

<Comparative Example 1>

A polypropylene resin having a melt flow index (MFR) of 1,200 and a polyethylene resin having a melt flow index (MFR) of 600 are prepared. Two types of materials are melted at a spinning temperature of 280℃, and then spun through a nozzle with a diameter of 0.23mm and a density of 22/10mm pores. At this time, the temperature of the stretching air to be used is 310°C, and the supply pressure is 0.6 Kg/cm 2 .

The supply amount of polypropylene resin and polyethylene resin was the same at 50 wt %, and a composite fiber in the form of a sheath & core was formed to prepare a meltblown web. At this time, a polyethylene resin was formed on the surface (sheath) of the composite fiber, and a polypropylene resin was formed on the inside (core) of the composite fiber. The distance between the nozzle and the collector was 76 mm, and the fiber diameter of the prepared composite fiber was 1.2 to 4.5 μm.

A melt-blown nonwoven fabric was prepared without hot-melt and calendering of the prepared melt-blown web.

<Comparative Example 2>

A polypropylene resin having a melt flow index (MFR) of 1,200 and a polyethylene resin having a melt flow index (MFR) of 600 are prepared. Two types of materials are melted at a spinning temperature of 280℃, and then spun through a nozzle with a diameter of 0.23mm and a density of 22/10mm pores. At this time, the temperature of the stretching air to be used is 310°C, and the supply pressure is 0.6 Kg/cm 2 .

The supply amount of polypropylene resin and polyethylene resin was the same at 50 wt %, and a composite fiber in the form of a sheath & core was formed to prepare a meltblown web. At this time, a polyethylene resin was formed on the surface (sheath) of the composite fiber, and a polypropylene resin was formed on the inside (core) of the composite fiber. The distance between the nozzle and the collector was 76 mm, and the fiber diameter of the prepared composite fiber was 1.2 to 4.5 μm.

The prepared meltblown web was coated with an emulsion polyurethane resin in an application amount of 38wt%, dried, and then passed through a calender roll and pressed to prepare a meltblown nonwoven fabric.

<Test Example 1>

The test and measurement method was based on JIS L1906 (Method for measuring the physical properties of long fiber nonwoven fabrics). The main measurement methods are as follows.

- Hydrostatic pressure measurement method (ISO 811, mmH ₂ O)

- Moisture permeability measurement method (KS K0594, potassium acetate method, gr/㎡/24Hrs)

- Abrasion strength measurement method (ASTM D3884, Taber Method, CS-10 wear wheel)

JIS L1906 is used for the criteria for determining the wear strength after the wear strength test.

- For the evaluation of the decrease in moisture permeability during long-term use, the air filter performance evaluation method was first used to simulate clogging of pores of porous materials by fine dust during long-term use. The fine dust used was ISO 12103 (A2 Fine), and the area of the sample to be tested was 0.05 m2, the dust concentration was 0.5 gr/m, and the wind speed was 1.3 m/sec. was evaluated under the conditions of It is determined that the sample that has undergone such a test may have clogged pores by fine dust, and the moisture permeability was re-evaluated and recorded.

division Preparation Example 1 Preparation 2 Preparation 3 Comparative Example 1 Comparative Example 2 target performance weight
(gsm) 60 56 65 54 73 75 or less The tensile strength
(N/cm) 35 27 53 4.5 - 25 or more wear strength
(class) 4 3.5 4.5 0 0 3 or more water pressure
(mmH₂O) 5,100 2,030 7,700 320 2,350 over 2,000 moisture permeability
(gr/
m/day brand new 3,900 4,600 3,200 21,000 2,230

1,000 or more After fine dust evaluation
1,300
1,800
1,050
18,300
650

The present invention has been looked at with a focus on preferred embodiments, and those of ordinary skill in the art to which the present invention pertains will implement embodiments other than the detailed description of the present invention within the essential technical scope of the present invention. will be able Here, the essential technical scope of the present invention is indicated in the claims, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

1: core part 2: sheath part

Claims (4)

forming a meltblown web made of composite fibers in which the core part is formed of polypropylene resin and the sheath part is formed of polyethylene resin;
applying a polyolefin-based hot melt resin to the melt blown web; and
Comprising the step of calendering thermal bonding of the melt blown web coated with the hot melt resin,
In the step of forming the melt blown web, the composite fiber has a diameter of 1.0㎛ ~ 5.0㎛,
In the step of applying the hot melt resin, when the hot melt resin is applied, the ambient temperature is maintained higher than the melting temperature of the hot melt resin, but lower than the melting temperature of the polyethylene resin forming the sheath part of the composite fiber, so that the sheath part is not melted In a state where the hot melt resin is melted, it penetrates into the interior of the composite fiber and is applied,
In the calender thermal bonding step, the calender consists of two rollers with a flat surface arranged vertically, and the melt blown web coated with the hot melt passes between the rollers and is heat-bonded by heating and pressing,
The method of manufacturing a moisture-permeable waterproof nonwoven fabric for footwear, characterized in that the pores between the composite fibers of the meltblown web coated with the hot melt resin coated with the calender thermal bonding are 0.5㎛ ~ 5.0㎛.
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