KR20190030095A - Air-permeable sheet and method for manufacturing air-permeable sheet - Google Patents

Abstract

According to one embodiment of the present invention, a method for manufacturing an air-permeable sheet comprises the steps of laminating and arranging at least one second microfiber web having a melting point higher than that of a first microfiber web between a pair of first microfiber webs; and inserting the first and second microfiber webs between a pair of mold plates and pressing a mold to a predetermined target temperature through the mold plates. The second microfiber web has a higher melting point than the first microfiber web, and the predetermined target temperature is lower than the melting point of the second microfiber web and higher than the melting point of the first microfiber web.

Description

TECHNICAL FIELD [0001] The present invention relates to an air-permeable sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a method of producing a breathable sheet and a breathable sheet, and more particularly to a breathable sheet and a breathable sheet which can realize various surface roughness values and air permeability.

In general, the peeling of the ceramic green sheet is performed by a vacuum force, and the peeling force varies depending on the shape of the structure capable of adsorbing the ceramic green sheet by vacuum.

Conventionally, a metal body or a metal sintered body having a surface hole machined in a portion contacting with a ceramic green sheet in vacuum is processed or used, or a hole having a predetermined interval is formed through etching on a metal plate.

However, there is a problem that the peeling mold is formed of a metal body, the contact portion of the ceramic green sheet is damaged, and the hole formed in the peeling mold also causes damage to the ceramic sheet.

If the surface of the ceramic green sheet for manufacturing the multilayer ceramic capacitor is damaged, the internal pattern formed on the surface of the ceramic sheet is damaged, resulting in product defects such as shorts after lamination.

As a result, studies have been made on a breathable adsorbent sheet which can be easily peeled off with a strong adsorption force without damaging the ceramic green sheet. A porous adsorbent sheet having a porous microporous polyethylene sheet Sheet is applied to a peeling lamination process of a multilayer ceramic capacitor.

1 is a scanning electron micrograph of a section of a porous sheet. The porous ultra-high molecular weight polyethylene sheet is manufactured through a process of sintering ultrahigh molecular weight polyethylene powder by using heated steam and then cutting after cooling. It is possible to manufacture a sheet of relatively thick thickness, and the surface roughness, Can be improved.

However, such a porous ultra-high molecular weight polyethylene sheet has a problem in that it is expensive to manufacture in the manufacturing process, and scattering of thickness, particle diameter, density and porosity between products occurs and it is difficult to reduce the pore size for ensuring air permeability. There was a difficult problem.

Korean Unexamined Patent Application Publication No. 2007-0089071 (Aug. 30, 2007)

It is an object of the present invention to provide a method of manufacturing a breathable sheet and a breathable sheet which can realize various breathability characteristics.

Another object of the present invention is to provide a method of manufacturing a breathable sheet and a breathable sheet which can apply various raw materials and can simplify a manufacturing process and minimize a product cost.

Other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

According to an embodiment of the present invention, a method of manufacturing a breathable sheet comprises laminating and arranging at least one second fine fiber web having a melting point higher than that of the first fine fiber web between a pair of first fine fiber webs, The first and second microfine fiber webs are sandwiched between a pair of mold plates and compressed through a mold plate at a predetermined target temperature, and the second microfine fiber web has a higher melting point than the first microfine fiber web , The temperature is lower than the melting point of the second microfine web and is higher than the melting point of the first microfine web.

The step of pressing with the target temperature may gradually increase the temperature at which the first and second fine fiber webs are pressed through the mold plate to the target temperature.

The method further comprises the step of gradually cooling the first and second microfine fiber webs to the takeout temperature and then removing the first and second microfine fiber webs from the mold plate, .

The extraction temperature may be lower than the melting point of the first microfine web.

The first and second fine fiber webs may each be one or a mixture of two or more selected from the group consisting of polyethylene, polyethylene terephthalate, polycarbonate, polypropylene, polystyrene and polyamide.

The fiber thickness of the second microfine fiber web may be greater than the fiber thickness of the first microfine fiber web.

According to another embodiment of the present invention, the breathable sheet comprises a pair of first microfine webs; And a second microfine fiber web layer disposed between the first microfine fiber webs and having one or more second microfine fiber webs laminated with a melting point higher than that of the first microfine fiber webs, And the second microfine fiber web has a higher melting point than the first microfine fiber web, and the second microfine fiber web has a larger fiber diameter than the first microfine fiber web.

According to one embodiment of the present invention, various air permeability characteristics of the air-permeable sheet can be realized through compression conditions of the fine fiber web, for example, compression temperature, pressure, compression time and the like.

In addition, various air permeability characteristics of the air-permeable sheet can be realized through the melting point of the fine fiber web, the fiber thickness and basis weight, and the amount of lamination.

1 is a scanning electron micrograph of a section of a porous sheet.
2 is a view schematically showing a process of manufacturing a breathable sheet according to an embodiment of the present invention.
3 is a flowchart schematically showing a method of manufacturing a breathable sheet according to an embodiment of the present invention.
4 is a result value showing characteristics of the breathable sheet according to an embodiment of the present invention.
5 and 6 are photographs showing a breathable sheet according to an embodiment of the present invention.
7 is a view schematically showing a mold apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to FIGS. 2 to 7 attached hereto. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments are provided to explain the present invention to a person having ordinary skill in the art to which the present invention belongs. Accordingly, the shape of each element shown in the drawings may be exaggerated to emphasize a clearer description.

2 is a view schematically showing a process of manufacturing a breathable sheet according to an embodiment of the present invention. The breathable sheet is produced using a high melting point fine fiber web and a low melting point fine fiber web.

In this embodiment, fine fibers mean fibers having a diameter of several tens of nanometers to a few thousand nanometers. In this embodiment, the diameter of the fine fibers may be 50 nm to 5000 nm, but is not limited thereto. In addition, various polymer materials can be used as raw materials depending on the application.

In this embodiment, the raw material of the fine fibers may be one or a mixture of two or more selected from the group consisting of polyethylene, polyethylene terephthalate, polycarbonate, polypropylene, polystyrene and polyamide, but is not limited thereto.

In this embodiment, the microfibers can be formed through electrospinning, wherein the electrospinning process is carried out by an electrostatic force using a polymer of low viscosity, To obtain the product.

Electrospinning is an important feature of making nanometer (nm) and micrometer (㎛) units of fibers by using a material having a diameter of millimeters (mm) There is an advantage that fibers having various thicknesses and properties can be produced according to the characteristics of the spinning solution (viscosity, surface tension, conductivity, etc.), the magnitude of the potential difference applied, and the distance between the nozzle and the collector.

For example, when a high-voltage electric field is applied to a polymer material, an electric repulsive force is generated inside the raw material to cause the molecules to aggregate and break into nanometer and micrometer-sized voids. At this time, the stronger the electric field, the finer the tearing can be. If the yarn thus drawn is gathered together without a separate weaving process, it is entangled to form a fine fiber web.

The fine fiber web thus formed has high porosity and excellent surface roughness because the microfibers constituting the fine fiber web are nanometer (nm) and micrometer (占 퐉) units.

The microfibrous web formed as above has an inherent melting point depending on its properties, and the high melting fiber (HMF) and the low melting fiber (LMF) have a relatively different melting point . That is, the high melting point microfibers have a higher melting point than the low melting point microfibers.

In this embodiment, the high melting point microfine fibers have a melting point of about 150 degrees and are gradually deformed above 150 degrees, and the low melting point microfine fibers have a melting point of about 80 degrees, and are gradually deformed at a temperature higher than 80 degrees.

As shown in FIG. 2, four layers of high melting point fine fiber webs are laminated and disposed between a pair of low melting point fine fiber webs, followed by pressing them to produce a breathable sheet. At this time, the fiber thickness, basis weight and laminated water amount of the high melting point fine fiber web are determined in consideration of the thickness of the breathable sheet and the air permeability. The low melting point fine fiber web may be a single layer, and the fiber thickness and basis weight of the low melting point fine fiber web are determined in consideration of the surface roughness of the breathable sheet.

3 is a flowchart schematically showing a method of manufacturing a breathable sheet according to an embodiment of the present invention. Hereinafter, a method of manufacturing a breathable sheet according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG.

The low-melting-point microfibers have a melting point of about 80 ° C. and have a web size of 1.5 denier weight of 50 g and are arranged side by side in a single layer. Also, the high-melting-point microfine fibers have a melting point of about 150 ° C. and have a web size of 6 denier and a weight of 60 g, and are laminated in four layers and disposed between a pair of low melting point microfine webs.

For reference, 1 denia denoting the fiber thickness corresponds to the thickness when 9,000 m of yarn is pulled out with 1 g of fiber, and the fiber basis weight corresponds to the weight when the fiber is distributed in a width of 1 m and a length of 1 m.

The low melting point microfine web and the high melting point microfine web formed as described above are placed between a pair of mold plates and pressed to a target temperature through a mold plate (see FIG. 2). At this time, the target temperature is about 130 degrees which is higher than the melting point of the low melting point microfine fibers and lower than the melting point of the high melting point microfine fibers. The pressing temperature gradually increases to reach the target temperature for about 15 seconds, , The compression time is set to about 30 seconds, and the compression pressure is set to about 100 tons. That is, in the state where the low melting point fine fiber web and the high melting point fine fiber web are positioned between the pair of mold plates, the mold plate is heated to gradually increase the compression temperature to the target temperature (takes about 15 seconds) The compression is performed for about 30 seconds by the above compression conditions (mold interval, compression time, compression pressure).

At this time, the temperature of the mold plate should be easily adjusted, the gap between the mold plates should be easy to adjust, and the gap between the mold plates should be ± 0, so that the thickness deviation of the breathable sheet is not affected. Further, the surface of the mold can be made of PTFE coating or DLC coating for easy extraction. In addition, the temperature of the mold must be uniformly raised and cooled as a whole.

Thereafter, the pair of mold plates is gradually cooled to reach the blowout temperature, whereby the low melting point microfine web and the high melting point microfine web are also cooled to the extraction temperature. The extraction temperature is about 60 degrees below the melting point of the low melting point microfine fibers, and the time from the target temperature to the extraction temperature is about 15 seconds, and then the low melting point microfine web and the high melting point microfine web are taken out.

The result of the breathable sheet produced by the above method was derived as 0.4 mm thickness, 2.5-3 cm3 / cm2 / s of air permeability, and 3.38 탆 Rz of 24.74 탆 of surface roughness Ra. 4 is a result value showing characteristics of the breathable sheet according to an embodiment of the present invention. For reference, Rz, that is, "the difference between the average of the Z data of the fifth highest peak from the highest peak on the specific surface and the average of the Z data of the fifth lowest valley from the lowest valley & Respectively.

On the other hand, when the air permeability is insufficient, the surface roughness is excellent but the object to be adsorbed can not be effectively adsorbed. When the surface roughness is low, the air permeability is sufficient, but there is a problem that the surface of the object to be adsorbed is damaged due to unevenness of the surface of the sheet.

5 and 6 are photographs showing a breathable sheet according to an embodiment of the present invention. As shown in FIGS. 5 and 6, the crossing points between the fiber yarns are relatively large and the pores are sufficient, and the air permeability can be adjusted by adjusting the weight of the fiber yarn according to the requirements of the customer. Further, since the pores are not located at the same positions, the air permeability can be ensured at any portion of the sheet.

On the other hand, besides the above-described manufacturing method, it is possible to prevent the generation of static electricity by applying an antistatic liquid to the breathable sheet (or the low melting point fine fiber web or the high melting point fine fiber web), and by using black fine fibers A breathable sheet can be produced.

The breathable sheet can be used as a porous adsorbent sheet applicable to, for example, adsorption peeling, vacuum adsorption process (LCD scribing, OLED inspection process, and the like) in the production of a liquid crystal glass plate, a semiconductor wafer or a multilayer ceramic capacitor.

Also, the porous sheet according to this embodiment is applicable to a separation membrane of a secondary battery comprising a cathode active material, an anode active material, an electrolyte, and a separation membrane.

Here, the secondary battery refers to a battery which can be used again after returning to its original state by recharging by using external energy after discharge. Such a secondary battery can have a high power density, a high output discharge capability, and a low temperature influence.

As described above, the secondary battery is composed of four major components, namely, a cathode active material, an anode active material, an electrolyte, and a separator. The separator separates the cathode active material and the anode active material, do.

Since the separation membrane is required to provide a passage for ion movement and to prevent the movement of foreign matter, the pore size is required to be several micrometers (탆) or less.

On the other hand, through various experiments, it has been found that increasing the thickness of the high melting point fine fibers or decreasing the number of laminated high melting point fine fiber webs increases the air permeability, conversely decreasing the thickness of the high melting point fine fibers, It has been confirmed that increasing the number of fiber webs reduces the air permeability.

When the target temperature of the mold plate is increased, deformation of the low-melting-point microfibers is increased and the air permeability can be reduced. When the target temperature of the mold plate is lowered, the deformation of the low- A bristle phenomenon may be present. As a result, it can be seen that the target temperature, the squeezing time and the squeezing pressure are closely related to the surface roughness and the air permeability. Depending on the desired specifications, the raw material and the formation method of the fine fibers, the number of laminations of the high- It is important to accurately set the squeezing time and the squeezing pressure.

8 is a view schematically showing a mold apparatus according to an embodiment of the present invention. Referring to Fig. 8, the injection mold includes a fixed mold plate 10 and a movable mold plate 20 provided so as to be movable back and forth with respect to the stationary mold plate 10. The cavity 30 for molding the resin is defined by the uneven surfaces 31 and 32 formed on the opposing surfaces of the mold plates 10 and 20 when the pair of mold plates 10 and 20 are molded. In this embodiment, the fixed mold plate 10 is formed with the recessed cavity surface 31, and the movable mold plate 20 is provided with the protruded core surface 32. Each of the mold plates 10 and 20 is fixed to mounting plates 40 and 50 fixed to an injection machine (not shown).

Porous members (71, 72) are inserted into the respective mold plates (10, 20). The porous members (71, 72) use a porous metal which is excellent in thermal conductivity and resistant to corrosion. As the porous metal, copper, aluminum, nickel or the like is used. The structure of the pore of the porous metal uses an open cell type in which the flow resistance of the fluid is small. The porous members 71 and 72 of the present embodiment are in the form of hollow cylinders. In this embodiment, hollow cylindrical porous members 71 and 72 having a long length are used. However, if necessary, a plurality of hollow cylindrical porous members having a short length may be connected adjacent to each other.

The heaters (61, 62) for heating are inserted into the hollows of the porous members (10, 20). The electric heaters 61 and 62 use a heater of a cartridge type. The movable mold plate 20 is provided with a temperature sensor 90 for measuring the temperature.

Each of the mold plates 10 and 20 is provided with supply passages 81 and 82 formed to communicate with one side of the inserted porous members 71 and 72 and discharge passages 81 and 82 formed to communicate with the other side of the porous members 71 and 72, (83, 84), respectively. 8, the supply passage 81 formed in the stationary mold plate 10 is formed to communicate with one end of a plurality of porous members 71, and is connected to the pipe a1. The pipe a1 is connected to the pump 93 to supply water to the supply passage 81. [ The discharge passage 83 formed in the fixed mold plate 10 is formed to communicate with the other end of the plurality of porous members 71 and is connected to the pipe d1. The pipe d1 is connected to the vacuum pump 92. The supply passage 82 of the movable mold plate 20 is connected to the pipe a2 connected to the pump 93 and the discharge passage 84 is connected to the pipe d2 connected to the vacuum pump 92. [

In addition, stoppers 11 and 21 for sealing the discharge passages 83 and 84 and supply passages 81 and 82 are sealed in the respective mold plates 10 and 20 and heaters 61 and 62 And heater support caps 85 and 86 for supporting the heater support caps 85 and 86 are provided. The stoppers 11 and 21 and the support caps 85 and 86 seal the inside of the mold plates 10 and 20, respectively.

The water tank 96 contains water, which is a heat transfer medium for heating or cooling the mold plates 10 and 20. It is preferable to use distilled water to prevent water from corroding the porous members 71 and 72 and the mold plates 10 and 20. [ A filter 95 for filtering the fine particles contained in the water is installed in the pipe g between the pump 93 and the water tank 96 in order to prevent the pores of the porous members 71 and 72 from being clogged have.

The pump 93 pressurizes the water in the water tank 96 and supplies the water to the supply passages 81 and 82 of the respective mold plates 10 and 20 through the pipes a, a1 and a2. The vacuum pump 92 is connected to the discharge passages 83 and 84 of the mold plates 10 and 20 through the pipes d, d1 and d2. The vacuum pump 92 sucks the water supplied to the porous members 71 and 72 and discharges the water to the water tank 96. A cooling device for cooling circulating water may be installed between the water tub 96 and the mold plates 10 and 20 although not shown.

The pipe a is connected to a pipe c for supplying compressed air from the compressed air source 94 to the supply passages 81 and 82 of the mold plates 10 and 20. The water charged in the porous members 71 and 72 is supplied to the pipes d1 and d2 connected to the discharge passages 83 and 84 of the respective mold plates 10 and 20 by the vacuum pump 92 And a bypass pipe e for discharging the water to the water tank 96 without passing through the pipe. The controller 91 receives the signal of the temperature sensor 90 and controls the operation of the valves 97, 98, 99, 101, 102 and the pump 93 and the vacuum pump 92. Further, the controller 93 applies or cuts off power to the electrothermal heaters 61 and 62 when the mold is heated or cooled.

In order to shorten the heating and cooling time in the rapid heating / cooling apparatus for the molding die of the present invention, it is necessary to make the heat transfer effective by closely contacting the mold plate and the porous member inserted in the mold plate. In order to ensure close contact between the mold plate and the porous member during cooling and heating, it is preferable to assemble the porous member and the mold plate.

As shown in Fig. 8, in the molding die according to the present invention, the heat-insulating holes 15 and 25 are provided in the respective mold plates 10 and 20, respectively. The heat insulating holes 15 and 25 are arranged behind the porous members 71 and 72 with respect to the cavity surface 31. The heat of the electrothermal heaters 61 and 62 is applied to the cavity surfaces 31 and 32 of the mold plates 10 and 20 at the time of heating the mold plates 10 and 20 by filling the heat insulating holes 15 and 25 with air having a low heat transfer coefficient. So that the heat of the heat transfer heaters 61 and 62 is concentrated on the cavity surface 31 and the cooling air of the cooling medium during the cooling of the mold plates 10 and 20 is transferred to the mold plates 10 and 20 In the direction opposite to the cavity surface 31 of the cavity surface 31 so that the cool air of the cooling medium is concentrated on the cavity surface 31. [

Although the circular heat insulating holes 15 and 25 are shown as being provided in the number corresponding to the number of the porous members 71 and 72, the shape and the number of the heat insulating holes 15 and 25 are variously changed . For example, one long heat insulating hole may be provided behind the plurality of porous members 71, 72.

Referring to Fig. 8, the rapid heating / cooling method of the molding die of the present embodiment will be described. First, the pump 93 is operated to supply water to the supply passages 81, 82 through the pipes a, a1, a2. When the supplied water is filled in the porous members 71 and 72, the valves 97 and 98 and the valve 101 are closed to seal the supply passages 81 and 82 and the discharge passages 83 and 84. Water is filled in the pores of the porous members 71 and 72 and the heat transfer heaters 61 and 62 are closed while the supply passages 81 and 82 and the discharge passages 83 and 84 of the mold plates 10 and 20 are closed, . Heat generated from the electrothermal heaters 61 and 62 is transmitted to the mold plates 10 and 20 through the water filled in the porous members 71 and 72 and the spaces of the porous members 71 and 72, 20).

At this time, water filled in the cavities of the porous members (71, 72) in the closed mold plates (10, 20) is heated so that the temperature rises as the pressure rises and becomes superheated water vapor so that the mold plates And then heated to a uniform temperature. When the temperature of the mold plates 10 and 20 reaches a predetermined temperature or more, a molding material (synthetic resin in the case of injection molding) is injected into the cavity 30 of the mold. When the injection of the resin is completed, the closed valves 97, 98 and 101 are opened and the pump 93 is operated to allow the water to flow through the voids of the porous members 71 and 72, . When the temperature of the mold plates 10, 20 becomes lower than a predetermined temperature, the supply of water is stopped.

In this embodiment, there are two methods of cooling the mold plates 10 and 20 by passing water (heat transfer medium) through the air gap of the porous members 71 and 72. One method is to operate the pump 93 or the vacuum pump 92 so that the supplied water passes through the pores of the porous members 71 and 72 while absorbing heat to be discharged in a state where the temperature is raised. That is, when the supplied water passes through the pores of the porous members 71 and 72, the suction pressure of the vacuum pump 92 is adjusted so that the water is not evaporated.

The pressure difference between the porous members 71 and 72 causes pressure difference between the porous member 71 and the porous member 71 when the water is pressurized by the pump 93 while being sucked into the vacuum pump 92, 71, and 72, respectively. The pressure of the discharge passages 83 and 84 is maintained at a temperature higher than the pressure at which evaporation does not occur at the temperature of the water heated and discharged in order to prevent water from evaporating in the voids or the discharge passages 83 and 84 of the porous members 71 and 72 do. The conditions under which water does not evaporate at a given temperature can easily be obtained from the vapor pressure curve for water.

Another method is to allow the supplied water to evaporate while passing through the voids or discharge passages of the porous members 71 and 72 to absorb the heat of evaporation from the mold plates 10 and 20 to rapidly cool the mold plates 10 and 20. [ Method. Evaporation heat is needed when the liquid evaporates into gas. Water requires a pressure of 2 kPa, vaporization of 2,460 kJ / kg when vaporized at 17.5 ℃, and vaporization of 2,444 kJ / kg when pressure of 3 kPa and vaporization at 24 ℃. The pressure of the discharge passages 83 and 84 is kept sufficiently low by the vacuum pump 92 so that evaporation takes place at the temperature of the water discharged to the discharge passages 83 and 84.

For example, when the temperature of the water discharged to the discharge passages 83 and 84 is 24 ° C. or higher, if the pressure of the discharge passages 83 and 84 is maintained at 3 kPa or lower, the air gap of the porous members 71 and 72 And heat of about 2,444 kJ / kg is absorbed from the mold plates (10, 20) while evaporation takes place in the discharge passages (83, 84). Therefore, by controlling the temperature and the flow rate of the water supplied to the supply passages 81 and 82 during cooling, the cooling temperature and the cooling time of the mold plates 10 and 20 can be adjusted.

Although the present invention has been described in detail by way of preferred embodiments thereof, other forms of embodiment are possible. Therefore, the technical idea and scope of the claims set forth below are not limited to the preferred embodiments.

Claims (5)

Wherein at least one second fine fiber web having a melting point higher than that of the first fine fiber web is disposed between the pair of first fine fiber webs,
The first and second fine fiber webs are sandwiched between a pair of mold plates, and are compressed at a predetermined target temperature through the mold plate,
Wherein the second microfine fiber web has a higher melting point than the first microfine fiber web,
Wherein the temperature is lower than the melting point of the second microfine fiber web and higher than the melting point of the first microfine web. The method according to claim 1,
The method of claim 1,
Wherein a temperature at which the first and second fine fiber webs are compressed through the mold plate gradually increases to the target temperature. 3. The method of claim 2,
The method may further comprise, after the step of squeezing to the target temperature,
Further comprising the step of gradually cooling the first and second microfine fiber webs to a takeout temperature, and then removing the first and second microfine fiber webs from the mold plate. The method of claim 3,
The take-out temperature is lower than the melting point of the first microfine web,
Wherein the fiber thickness of the second microfine fiber web is larger than the fiber thickness of the first microfine fiber web. A pair of first microfine webs; And
A second microfine fiber web layer disposed between the first microfine fiber webs and having at least one second microfine fiber web layer having a melting point higher than that of the first microfine fiber web layer,
Wherein the second microfine fiber web has a higher melting point than the first microfine fiber web,
Wherein the fiber thickness of the second microfine fiber web is larger than the fiber thickness of the first microfine fiber web.

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