WO2019050127A1 - Waterproof breathable sheet and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a waterproof breathable sheet and a manufacturing method thereof, the waterproof breathable sheet comprising a nano-membrane comprising nano-fibers laminated in a non-woven fabric form including multiple pores and a support body for supporting the nano-membrane, wherein breathability thereof is at least 1,000 mL/min at a pressure of 1 PSI. The waterproof breathable sheet suppresses a delamination phenomenon between layers of the nano-membrane comprising the nano-fibers to maximize the maintenance of an adhesive strength between the nano-membrane and an adhesive layer and prevents breathability degradation due to the pressure caused when the nano-membrane and the support body are joined together, to secure an excellent waterproof property and breathability.

Description

Waterproof breathable sheet and manufacturing method thereof

The present invention relates to a waterproof breathable sheet and a method of manufacturing the same. More particularly, the present invention relates to a waterproof breathable sheet which suppresses interlayer peeling of a nanofiber composed of nanofibers to maximize adhesion between the nanofiber and the adhesive layer, To a waterproof breathable sheet excellent in waterproofness and air permeability by preventing the decrease in air permeability due to pressure during lamination and a method for manufacturing the same.

In a variety of electronic devices such as mobile devices and hearing aids, communication devices such as radio transmitters, automobile head lamps, etc., permeability is imparted to the electronic devices to maintain pressure balance inside / outside the electronic devices, Waterproof to prevent penetration of water / liquid into the inside, and dustproof to prevent contamination / dust penetration. Accordingly, the electronic devices include a waterproof ventilation sheet having both waterproof / dustproof and air permeability.

Conventionally, the waterproof breathable sheet has been produced mainly using a porous polytetrafluoroethylene (PTFE) membrane. The porous PTFE membrane may be formed by melt extrusion or rolling a PTFE fine powder and uniaxially or biaxially stretched to form micropores. At this time, the pore size and the air permeability can be controlled according to the conditions of the extrusion and the drawing process.

However, since the porous membrane is made thin in thickness for air permeability and easily damaged due to external force, it is difficult to use it as a waterproof breathable sheet. Therefore, a separate support is used with the porous membrane. The support may be fabric or knitted fabric and may be mainly non-woven to maximize breathability.

However, if the porous membrane is combined with the support, the waterproof property can be maximized, but the air permeability is lowered.

It is an object of the present invention to provide a nano-membrane and a pressure-sensitive adhesive layer which are capable of maximizing maintenance of adhesion between the nanomembrane and an adhesive layer by suppressing delamination of a nanomembrane made of nanofibers, Thereby providing an excellent waterproof ventilation sheet.

Another object of the present invention is to provide a method of manufacturing the waterproof breathable sheet.

According to an embodiment of the present invention, there is provided a nanomembrane comprising a nanomembrane in which nanofibers are stacked in a nonwoven fabric including a plurality of pores, and a support for supporting the nanomembrane, wherein the permeability is 1,000 mL / min or more at a pressure of 1 PSI Thereby providing a waterproof ventilation sheet.

The nanomembrane is formed by laminating two to ten layers of the nanofibers, and the interlayer peel strength of the nanofibers may be 100 gf / 25 mm to 500 gf / 25 mm.

The first layer and the second layer adjacent to each other of the nanofibers in the nanomembrane may include a fusion bonding portion in which the nanofibers of the first layer and the nanofibers of the second layer are fusion-bonded to each other.

The peel strength of the nanomembrane and the support may be 500 gf / 25 mm to 2,000 gf / 25 mm.

Wherein the waterproof ventilation sheet further comprises a moisture-curing hot-melt adhesive for bonding the nanomembrane and the support between the nanomembrane and the support, wherein the adhesive has a dot or mesh pattern, The application amount of the adhesive may be 6 g / m ² or less.

Wherein the waterproof ventilation sheet further comprises a soluble hot melt adhesive for adhering the nanomembrane and the support between the nanomembrane and the support, wherein the adhesive has an irregularly dispersed dot shape and the application amount of the adhesive is less than or equal to 6 g / m ² or less.

The nanomembrane may include a fused joint where the nanofibers are fusion bonded to the support.

The support may be a thermal bonding nonwoven fabric, and the support may be disposed on both sides of the nanomembrane.

The nanomembrane may have an air permeability of 1 CFM to 20 CFM (cubic feet per minute), and the nanomembrane may have a water pressure of 3,000 mmH ₂ O or more.

Wherein the waterproof ventilation sheet has a tear strength of 0.5 kgf / cm 2 to 7 kgf / cm 2, the waterproof ventilation sheet has an air permeability of 0.5 CFM to 9 CFM, and the waterproof ventilation sheet has a water pressure of 3,000 mmH ₂ O to 12,000 mmH ₂ O, and the waterproof breathable water repellent sheet is rated at least quaternary, the waterproof breathable waterproof sheet has water pressure at room temperature conditions (20 ℃, ± 5 ℃) , low temperature conditions (-20 ℃, measured and kept 72 hours) (Measured after 50 sec. Of humidity, 95% of humidity after 72 hours of holding) and a thermal shock condition (measured after repeating 30 cycles of one cycle of maintaining -40 deg. C and 85 deg. lt; RTI ID = 0.0 > m < / RTI >

The nanofibers may be made of polyvinylidene difluoride (PVdF).

The support may be a polyester spunbonding or a thermal bonding nonwoven fabric.

The waterproof breathable sheet may further include an adhesive layer on one surface of the nanomembrane.

According to another embodiment of the present invention, there is provided a method of manufacturing a nanostructure, comprising the steps of: preparing an electrospinning solution; electrospinning the prepared electrospinning solution to produce a nanomembrane in which nanofibers are integrated into a nonwoven fabric including a plurality of pores; The present invention also provides a method of manufacturing a waterproof breathable sheet having a breathability of 1,000 mL / min or more at a pressure of 1 PSI, comprising the step of laminating a support to the nanomembrane.

The method may further include a step of heat-treating the nanomembrane at a temperature not lower than a melting initiation temperature of the nanofibers between the step of preparing the nanomembrane and the step of bonding the support.

In the heat-treating step, the heat-treating temperature may be 110 to 170 ° C.

The step of laminating the support may be performed by applying a moisture-curing hot-melt adhesive to the nanomembrane or the support using a gravure coater.

The step of laminating the support may be performed by spraying an available hot melt adhesive onto the nanomembrane or the support.

The step of laminating the support may be to melt-adhere the nanofibers of the nanomembrane at a temperature between the melting initiation temperature of the nanomembrane and the glass transition temperature of the support.

The step of laminating the support may be performed by disposing a thermal bonding nonwoven fabric, which is a support on both sides of the nanomembrane, and thermally bonding the support.

The waterproof breathable sheet of the present invention suppresses delamination between nanomembranes made of nanofibers, thereby maximizing the adhesion between the nanomembrane and the adhesive layer, preventing deterioration of air permeability due to pressure during bonding of the nanomembrane and the support, And air permeability are both excellent.

Fig. 1 is a perspective view schematically showing one embodiment of the waterproof breathable sheet of the present invention. Fig.

2 is a perspective view schematically showing a jig used in a water pressure measuring instrument for measuring water pressure and water resistance.

3 is a schematic view of a nozzle type electrospinning device.

4 is a scanning electron microscope (SEM) photograph of the nanomembrane prepared in Example 1. Fig.

5 is a scanning electron microscope (SEM) photograph of the nanomembrane prepared in Comparative Example 1. FIG.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

The waterproof breathable sheet according to an embodiment of the present invention includes a nanomembrane in which nanofibers are stacked in a nonwoven fabric including a plurality of pores and a support for supporting the nanomembrane and has a breathability of 1,000 mL / min.

Fig. 1 is a perspective view schematically showing one embodiment of the waterproof breathable sheet of the present invention. Fig. Hereinafter, the waterproof breathable sheet will be described with reference to FIG.

1, the waterproof breathable sheet 100 includes a nanomembrane 10 in which nanofibers are integrated in a nonwoven fabric including a plurality of pores and a support 20 for supporting the nanomembrane 10 And optionally an adhesive layer 30 on one surface of the nanomembrane 10.

1, the waterproof ventilation sheet 100 is shown as being circular. However, the present invention is not limited thereto, and the waterproof ventilation sheet 100 may have a circular shape, an elliptical shape, a rectangular shape, P-shaped, or the like.

1, the adhesive layer 30 is located on only one surface of the nanomembrane 10, but the present invention is not limited thereto. The adhesive layer 30 may be formed on the surface of the nanomembrane 10, As shown in FIG.

The nanomembrane 10 prevents the infiltration of water / liquid into the electronic device and the infiltration of pollution / dust by the porous structure formed by the nanofibers, and at the same time, It can be used to maintain internal / external pressure equilibrium.

For this purpose, the nanomembrane 10 may be made of a polymer having excellent hydrophobicity, chemical resistance, heat resistance, and processing characteristics, and specifically includes, for example, a polyolefin such as polyamide, polyester, polyethylene or polypropylene, polyvinylidene fluoride Such as polyvinylidene difluoride (PVdF), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetrafluoroethylene (perfluoroacryl) vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) A polyimide polymer such as polyimide (PI), polyetherimide (PEI) and polyamideimide (PAI), polyether sulfone (PES), polyacrylonitrile (PAN) and the like.

Conventionally, the waterproof breathable sheet 100 is mainly made of a porous PTFE sheet. Specifically, the porous PTFE sheet can be produced by forming a kneaded product of a PTFE fine powder and a molding auxiliary agent into a sheet by extrusion molding and rolling, removing the forming auxiliary agent to obtain a sheet body of the formed body, and then stretching the sheet body have. However, since the porous PTFE sheet is liable to shrink due to the lapse of time and heat, the waterproof breathable sheet 100 shrinks and the adhesive layer 30 is exposed.

Accordingly, it is preferable that the nanomembrane 10 is a nanoweb fabricated by electrospinning the PVdF. Since the PVdF is excellent in hydrophobicity, chemical resistance, and heat resistance, the nanomembrane 10 manufactured by electrospinning it can have excellent waterproofing and waterproofing properties and air permeability.

However, the nano-web produced by electrospinning the PVdF can be formed by laminating two to ten layers of nanofibers. The disadvantage of the nanofibers is that the delamination strength of the nanofibers is weak due to the spacing between the nozzles and the nip in the electrospinning process have. If the interlaminar peeling strength of the nanofibers is weak, the strength of the nanomembrane 10 itself is weak, and adhesion between the nanomembrane 10 and the adhesive layer 30 may not be maintained.

In order to solve the interlayer delamination of the nanofibers, there is a method of lowering the ratio of the solid content in the composition of the electrospinning solution, lowering the temperature in the electrospinning condition, or lowering the spinning distance between the nozzle or nip and the accumulating part. However, in this method, since the solvent volatilization is not smooth, the produced nanomembrane 10 may be produced as a film rather than a fiber, resulting in a decrease in air permeability.

In order to solve such a problem, the waterproof ventilation sheet 100 according to an embodiment of the present invention is formed by stacking 2 to 10 layers of the nanofibers of the nanomembrane 10, The peel strength is 100 gf / 25 mm to 500 gf / 25 mm, and the air permeability is 1,000 mL / min or more at a pressure of 1 PSI. That is, heat treatment at a temperature above the melting point of the nanofiber polymer can improve the interlaminar peeling strength of the nanofibers and maximize adhesion between the nanomembrane 10 and the adhesive layer 30. Accordingly, the first layer and the second layer adjacent to each other of the nanofibers in the nanomembrane 10 include a fusion bonding portion in which the nanofibers of the first layer and the nanofibers of the second layer are fusion-bonded to each other can do.

The thickness reduction ratio of the nanomembrane 10 may be 20% to 40% depending on the degree of melting of the nanofiber. If the reduction rate of the thickness of the nanomembrane 10 is less than 20%, the interlaminar detachment of the nanofibers may occur and the waterproof performance may be deteriorated. If the thickness reduction rate exceeds 40% The permeability may be lowered. The thickness reduction rate can be calculated by the following equation (1).

[Equation 1]

Thickness reduction rate (%) = (h-h ') / h X 100

h: Thickness of the nanomembrane before forming the fused joint

h ': the thickness of the nanomembrane after the formation of the fusion joint (heat treatment)

When the number of the nanofibers is less than 2, the thickness of the nanofiber 10 may not be sufficient, and when the number of the nanofibers is more than 10, The thickness of the honeycomb structure 10 may be increased and the air permeability may be lowered. The number of layers of the nanofibers can be confirmed by a cross-sectional photograph of the scanning electron microscope at the end face of the nanomembrane 10 or by attaching an adhesive tape to the nanomembrane 10 and then peeling off the number of layers of the nanofiber . ≪ / RTI >

In the nanomembrane 10 of the present invention, the interlaminar peel strength of the nanofibers is 100 gf / 25 mm to 500 gf / 25 mm, and more specifically 150 gf / 25 mm to 250 gf / 25 mm. The interlaminar peeling strength of the nanofibers was measured with a PEEL TESTER (AR-1000, ChemInstruments) satisfying ASTM D 3330 as a 180-degree peel strength measurement method of an adhesive tape and a pressure-sensitive adhesive sheet with a width of 25 mm, a length of 200 mm, 300 mm / min. When the interlaminar peeling strength of the nanofibers is less than 100 gf / 25 mm, the waterproof performance may be deteriorated, and when it exceeds 500 gf / 25 mm, the air permeability may be lowered.

Also, as the interlaminar peeling strength of the nanofibers in the nanomembrane 10 is enhanced, the peeling strength between the nanomembrane 10 and the support 20 can be strengthened, And the support 20 may have a peel strength of 500 gf / 25 mm to 2,000 gf / 25 mm, and specifically 700 gf / 25 mm to 1,100 gf / 25 mm. The peel strength between the nanomembrane 10 and the support 20 was measured with a PEEL TESTER (AR-1000, ChemInstruments) satisfying ASTM D 3330, which is a 180 degree peel strength measurement method of an adhesive tape and a pressure sensitive adhesive sheet, 25 mm, length 200 mm, speed 300 mm / min. When the peel strength between the nanomembrane 10 and the support 20 is less than 500 gf / 25 mm, the nanomembrane 10 and the support body 20 may be damaged by impact during the process of manufacturing the waterproof breathable sheet 100, 20) can be separated, and if it exceeds 2,000 gf / 25 mm, the air permeability may be lowered.

Meanwhile, the nanomembrane 10 can maximize the air permeability of the nanomembrane 10 by controlling the electrospinning conditions during the production of the nanofibers by electrospinning the PVdF.

The nanomembrane 10 may have a diameter ranging from 50 nm to 3,000 nm, and more specifically, from 100 nm to 2,000 nm. The thickness of the nanomembrane 10 ranges from 3 to 40 μm, Specifically, the nanomembrane 10 may have a pore size of 0.1 to 5 m, specifically 0.1 to 4 m, a porosity of 40 to 90% And the basis weight of the nanomembrane 10 may be from 0.5 g / m 2 to 20 g / m 2, and specifically from 1 g / m 2 to 15 g / m 2.

The pore size of the nanomembrane 10 was measured using a capillary flow porometer (CFP) specified in ASTM F 316 to determine the average pore size and pore size at the diameter of the pore size of the pore size in the narrowest section The size distribution can be measured. The thickness of the nanomembrane 10 can be measured by the thickness measurement method defined in KS K 0506 or by applying KS K ISO 9073-2 and ISO 4593. [ The basis weight of the nanomembrane 10 can be measured by applying KS K 0514 or ASTM D 3776. The porosity of the nanomembrane 10 may be calculated according to the ratio of the volume of air to the total volume of the nanomembrane 10 according to Equation (2). In this case, a rectangular volume sample is prepared and measured by measuring the width, length, and thickness, and the air volume can be obtained by subtracting the volume of the polymer inversely calculated from the density after measuring the mass of the sample from the total volume.

&Quot; (2) "

The porosity (%) = [1 - (A / B)] 100 = {1 - [(C / D) / B]

(Where A is the density of the nanomembrane, B is the density of the nanomembrane polymer, C is the weight of the nanomembrane, and D is the volume of the nanomembrane)

The nanomembrane 10 has an air permeability of 1 CFM to 20 CFM (cubic feet per minute), and specifically, the nanomembrane 10 has an air permeability of 3 CFM CFM to 7 CFM. The air permeability of the nanomembrane 10 can be measured under the conditions of an area of 38 cm 2 and a pressure of 125 Pa in accordance with ASTM D 737, which is a method of measuring air permeability of a fabric. An air permeability tester (air permeability tester) satisfying ASTM D 737 ) (FX 3300, Textest Instruments). When the air permeability of the nanomembrane 10 is less than 1 CFM, the water pressure is increased but the water-permeable ventilation sheet 100 may have low air permeability. If the air permeability of the water-permeable ventilation sheet 100 is more than 20 CFM, The adhesive may escape from the back surface of the nanomembrane 10 and may not be easily joined.

In addition, the above described nano-membrane 10 is included as a nano web produced by electrospinning the PVdF, the nano-membrane 10 includes a water pressure resistance is at least 3,000 ㎜H ₂ O, specifically water pressure is 5,000 ㎜H ₂ O to 12,000 ㎜H may be a O _2. The water pressure of the nanomembrane ₁₀ can be measured by applying pressure of 600 ㎜ H ₂ O / min at an area of 100 cm 2 by applying the ISO 811 low pressure method to measure the pressure at three points on the water droplet. When the water pressure of the nanomembrane 10 is less than 3,000 mmH ₂ O, the waterproof breathable sheet 100 including the nanomembrane 10 may not be waterproof.

In addition, since the nanomembrane 10 includes a nanoweb fabricated by electrospinning the PVdF, the nanomembrane 10 has a water repellency grade of 4 or more, specifically, a water repellency grade of 4 to 5 have. The water repellency of the nanomembrane 10 can be measured by the method specified in KS K 0590. If the water-repellency rating of the nanomembrane 10 is lower than 4, waterproof performance may be deteriorated.

The waterproof ventilation sheet 100 may have a tear strength of 0.5 kgf / cm 2 to 7 kgf / cm 2, and more specifically, a range of 2 kgf / cm 2 to 4.5 kgf / cm 2, as the inclusion of the nanomembrane 10. The rupture strength of the waterproof breathable sheet 100 may be measured by a Mullen type bursting strength tester which satisfies ASTM D 3786. [ When the rupture strength of the waterproof breathable sheet 100 is less than 0.5 kgf / cm 2, the waterproof breathable sheet 100 can be evaluated by the waterproof breathability sheet 100 The performance of the waterproof breathable sheet may be deteriorated if it exceeds 7 kgf / cm 2.

Also, the waterproof breathable sheet 100 may have a breathability of 1,000 mL / min or more, specifically, 1,500 mL / min to 3,000 mL / min. The air permeability of the waterproof ventilation sheet 100 is measured by a gas permeability method in a capillary flow porometer (CFP) using a flow rate of air passing through a 1 mm diameter circular area for 1 minute under 1 PSI pressure Can be measured. When the air permeability of the waterproof breathable sheet 100 is less than 1,000 mL / min, the pressure balance ability of the waterproof breathable sheet may be deteriorated.

The waterproof ventilation sheet 100 may have an air permeability of 0.5 CFM to 9 CFM, specifically, 3 CFM to 7 CFM. The air permeability of the waterproof ventilation sheet 100 can be measured under the conditions of an area of 38 cm 2 and a pressure of 125 Pa by ASTM D 737 which is a method of measuring the air permeability of a fabric, and the Air Permeability Tester (FX 3300, Textest Instruments). If the air permeability of the waterproof ventilation sheet 100 is less than 0.5 CFM, the air permeability may be lowered and the pressure balance capability may be deteriorated. If the air permeability exceeds 9 CFM, the waterproofness may not be maintained.

In addition, the breathable water-resistant sheet 100 is a water pressure resistance is at least 3,000 ㎜H ₂ O, may be specifically the water pressure 3,000 ㎜H ₂ O to 12,000 ㎜H ₂ O. The water pressure of the waterproof ventilation sheet 100 can be measured by applying pressure of 600 ㎜ H ₂ O / min at an area of 100 cm 2 by applying the ISO 811 low pressure method, thereby measuring the pressure at three points on the water drop. The water resistance and the water pressure of the vent seat 100 may be a problem that do not retain the water resistance is less than 3,000 ㎜H ₂ O, 12,000 waterproof if ㎜H exceed ₂ O may be a problem that the excellent one blockage .

The waterproof and waterproof performance of the waterproof ventilation sheet 100 can be measured using a water pressure meter capable of applying a constant water pressure of 0 m to 20 m depth used in KS K ISO 811 for a predetermined time. At this time, a jig may be used to measure the waterproofness of the waterproof ventilation sheet 100 in the water pressure measuring device.

2 is a perspective view schematically showing an embodiment of a jig used for measuring the waterproofness of the waterproof ventilation sheet 100 in the water pressure measuring instrument. 2, in a state where the waterproof ventilation sheet 100 is fixed or adhered to the jig 200, a certain water pressure is applied to the water pressure portion 210 using a water pressure meter for a predetermined period of time, have. 2, the number of the pressure receiving portions 210 is 19, but the present invention is not limited thereto. For example, the pressure receiving portion 210 may include one, three, five, nine, twenty The number can be adjusted. The size of the perforation hole of the pressure receiving portion 210 is preferably smaller than the open area of the perforated waterproof sheet 100 and can be appropriately adjusted according to the size of the perforated waterproof sheet 100.

In order to confirm the waterproof performance in various environments, it is possible to evaluate the waterproofing property after pretreatment under low temperature, high temperature / high humidity, thermal shock condition. In the case of low temperature, the sample was pretreated at -20 ° C for 72 hours, and the samples were subjected to a pre-treatment at 72 ° C for 72 hours at 50 ° C and a humidity of 95%. The thermal shock conditions were -40 ° C and 85 ° C One cycle, which is maintained for a period of time, can be repeated after 30 cycles.

The waterproof ventilation sheet 100 is not leaked at a normal temperature (20 ° C ± 5 ° C), a water pressure of 1.5 m or more for 30 minutes or more, specifically, a water pressure of 1.5 m to 6 m (50 ° C) for 30 minutes or more at a water pressure of 1.5 m or more, specifically for 30 minutes or more at a water pressure of 1.5 m to 6 m in the case of a low temperature condition (measured after holding at -20 ° C for 72 hours) , 95% humidity, and 72 hours), it does not leak more than 30 minutes at a water pressure of 1.5 m or more, specifically 30 minutes or more at a water pressure of 1.5 m to 6 m, And after repeating 30 cycles of maintaining the cycle for 1 hour each), the waterproofing waterproofing can not leak more than 30 minutes at a water pressure of 1.5 m or more, specifically, 30 minutes or more at a water pressure of 1.5 m to 6 m. When the waterproofing ventilation sheet 100 is waterproof and waterproof at room temperature (20 ° C ± 5 ° C) at a water pressure of 1.5 m or more, at a low temperature of 1.5 m or more, at a water temperature of 1.5 m or more at a high temperature / The waterproof performance of an electronic device using a ventilation sheet or the like may not be satisfied.

For reference, the water pressure at the certain depth can be calculated by the following equation (3). In the ocean, the water pressure increases by 1 atmospheres every time the water depth drops by 10 m.

&Quot; (3) "

Water pressure (p) = pgz

(In the equation 3, p is the density of water (about 1.03 g / ㎤), g is 980 cm / sec ^2, z is under the surface of the sea water depth (cm))

The waterproof ventilation sheet 100 may further include the support 20 to reinforce the strength of the nanomembrane 10.

The support 20 may be made of a material having a larger pore size than the nanomembrane 10 and having excellent gas permeability and excellent strength such as woven fabric, nonwoven fabric, mesh, net, sponge, foam, metal multi- Can be used. Further, when heat resistance is required, a support 20 made of polyester, polyamide, aramid resin, polyimide, fluorine resin, ultrahigh molecular weight polyethylene, metal or the like can be used.

Specifically, the nonwoven fabric may be interlaid with the support 20 formed of a plurality of randomly oriented fibers. The nonwoven fabric may be interlaid, but may be formed of a single fiber or filament, Quot; structure " The nonwoven fabric may be formed by a variety of processes including carding, garneting, air-laying, wet-laying, melt blowing, spunbonding, thermal bonding ), And stitch bonding. [0035] The term " stitch bonding " The fibers constituting the nonwoven fabric may include one or more polymeric materials, and any of them may be used as long as they are generally used as a polymeric material for fiber-forming. Specifically, hydrocarbon-based fiber-forming polymeric materials can be used. For example, the fiber-forming polymeric material may be a polyolefin such as polybutylene, polypropylene and polyethylene; Polyesters such as polyethylene terephthalate and polybutylene terephthalate; Polyamides (nylon-6 and nylon-6,6); Polyurethane; Polybutene; Polylactic acid; Polyvinyl alcohol; Polyphenylene sulfide; Polysulfone; A fluid crystalline polymer; Polyethylene-co-vinyl acetate; Polyacrylonitrile; Cyclic polyolefins; Polyoxymethylene; Polyolefinic thermoplastic elastomers; And combinations thereof. However, the present invention is not limited thereto.

More specifically, as the support 20, polyester spun bonding or thermal bonding nonwoven fabric may be most preferably used. When the polyester spunbonding or thermal bonding nonwoven fabric is used, it is highly permeable and less deformed under harsh environmental conditions It is advantageous in point. The support 20 may be a nonwoven fabric in which the polyester has a different melting point from the cis-core or mixed yarn, and the nonwoven fabric may be advantageous from the viewpoint of air permeability without the embossing treatment. The embossed nonwoven fabric has a structure in which the fibers of the embossed portion are fused and the pores are plugged, which can make the air permeability variation of the waterproof breathable sheet 100 large. In the waterproof ventilation sheet 100 according to another embodiment of the present invention, the peel strength of the nanomembrane and the support is 500 gf / 25 mm to 2,000 gf / 25 mm and the air permeability is 1,000 mL / min or more at a pressure of 1 PSI .

The nanomembrane 10 and the support 20 may be laminated with or without an adhesive. At this time, pressure can be minimized during the laminating process of the nanomembrane 10 and the support 20 to prevent the permeability of the nanomembrane 10, which is sensitive to pressure, from being lowered.

For example, the waterproof ventilation sheet 100 may include a moisture-curing hot-melt adhesive for bonding the nanomembrane 10 and the support 20 between the nanomembrane 10 and the support 20.

The moisture-curing hot-melt adhesive may be, for example, a urethane-based, acrylic-based, or silicone-based adhesive.

The adhesive may have a pattern in the form of a dot or a mesh. When the adhesive is applied on the entire surface without having a dot or mesh pattern, the adhesive is excessively adhered and the adhesive is leaked into the pores of the nanomembrane 10, The water pressure may be lowered due to the damage of the nanomembrane 10.

The dot or mesh pattern may be formed on the surface of the nanomembrane 10 at an interval of 5% to 25% of the circumference of the surface of the nanomembrane 10 in order to prevent the air permeability of the nanomembrane 10 from being lowered. May be formed along the circumference of the surface. When the pattern is less than 5% of the circumferential length of the surface of the nanomembrane, the adhesion between the nanomembrane and the support may deteriorate. If the pattern exceeds 25%, there is a problem that the waterproof performance and air permeability are lowered due to the adhesive .

In order not to lower the air permeability of the nanomembrane 10, the applied amount of the adhesive may be 6 g / m ² or less, specifically 1 g / m ² to 3 g / m ² . When the applied amount of the adhesive exceeds 6 g / m ² , the air permeability of the waterproof ventilation sheet may be lowered, and if the adhesive amount is less than 1 g / m ^2, the application of the adhesive may not be performed uniformly.

The waterproof ventilation sheet 100 may further include a soluble hot melt adhesive for adhering the nanomembrane 10 and the support 20 between the nanomembrane 10 and the support 20 .

The soluble hot melt adhesive may be, for example, a polyurethane type, a polyester type, a polyamide type, or the like.

As the adhesive is applied by spraying, it can have an irregularly scattered dot shape. Since the adhesive has irregularly scattered dot shapes, the adhesive is leaked into the pores of the nanomembrane 10 and the water permeability is lowered, and the water pressure is lowered due to the damage of the nanomembrane 10 due to the adhesive Can be solved.

Specifically, in order not to lower the air permeability of the nanomembrane 10, the amount of the adhesive applied is 6 g / m ² or less, specifically 1 g / m ² to 3 g / m ² . When the applied amount of the adhesive exceeds 6 g / m ² , the air permeability of the waterproof ventilation sheet may be lowered, and if the adhesive amount is less than 1 g / m ^2, the application of the adhesive may not be performed uniformly.

In another example, the nanomembrane 10 may include a fused bond in which the nanofibers are fused to the support 20. That is, the nano-membrane 10 and the support 20 can be solidified again after the nanofibers of the nanomembrane 10 are melted and bonded to the support 20 without the adhesive. In the case where the nanomembrane 10 and the support 20 are bonded together without the adhesive, the pores of the nanomembrane 10 are clogged by the adhesive to solve the problem that the permeability of the nanomembrane 10 is lowered . Accordingly, the nanofibers of the nanomembrane 10, which are in contact with the support 20, may include a fusion bonding portion fused to the support 20.

The thickness reduction ratio of the nanomembrane may be 20% to 40% depending on the degree of melting of the nanofiber. If the reduction rate of the thickness of the nanomembrane is less than 20%, the interlaminar peeling of the nanofiber may occur and the waterproofing performance may deteriorate. If the thickness reduction rate exceeds 40%, the melted portion of the nanofiber becomes a film, . The thickness reduction rate can be calculated by Equation (1).

In another example, the support 20 is a thermal bonding nonwoven fabric, and the nanomembrane 10 and the support 20 can be bonded to each other by thermal bonding of the support 20. At this time, the support 20 is preferably positioned on both sides of the nanomembrane 10.

Specifically, the thermal bonding nonwoven fabric includes a first fiber made of a high melting point polyethylene terephthalate (PET) and a second fiber made of a low melting point polyethylene terephthalate (PET), and the first fiber and the second fiber By mixing and spinning. The high melting point polyethylene terephthalate (PET) may have a melting point of 240 ° C or higher, and the low melting point polyethylene terephthalate (PET) may have a melting point of 120 ° C to 230 ° C. In this case, the content of the first fiber is 10 wt% to 90 wt%, specifically 30 wt% to 70 wt%, and the content of the second fiber is 10 wt% to 90 wt% based on the total weight of the thermal bonding non- , Specifically from 30% to 70% by weight.

As described above, the separation strength between the nanomembrane 10 and the support 20 is 500 gf / 25 mm to 2,000 mm, as the nanomembrane 10 and the support 20 are bonded together with or without an adhesive. gf / 25 mm, and specifically may be 700 gf / 25 mm to 1,100 gf / 25 mm. The peel strength between the nanomembrane 10 and the support 20 was measured with a PEEL TESTER (AR-1000, ChemInstruments) satisfying ASTM D 3330, which is a 180 degree peel strength measurement method of an adhesive tape and a pressure sensitive adhesive sheet, 25 mm, length 200 mm, speed 300 mm / min. When the peel strength between the nanomembrane 10 and the support 20 is less than 500 gf / 25 mm, the nanomembrane 10 and the support body 20 may be damaged by impact during the process of manufacturing the waterproof breathable sheet 100, 20) can be separated, and if it exceeds 2,000 gf / 25 mm, the air permeability may be lowered.

The adhesive layer 30 is located on the surface of the nanomembrane 10 and specifically the periphery 30a of the adhesive layer 30 is located around the surface of the nanomembrane 10, 30 may have an open frame shape. The nanomembrane 10 is attached to the inner surface of the vent hole of the housing of the electronic device through the adhesive layer 30 and the vent hole of the housing of the electronic device through the opening of the central portion 30b of the adhesive layer 30 It is possible to impart air permeability and waterproofness to the electronic device while blocking the air.

The shape and size of the opening of the central portion 30b of the adhesive layer 30 may be basically the same as the shape and size of the ventilation hole of the housing of the electronic apparatus. Specifically, the shape and size of the opening may be circular, oval, Rectangular, polygonal, P-shaped, and the like, but the present invention is not limited thereto.

The adhesive between the nanomembrane 10 and the support 20 in an area exposed through the opening of the central portion 30b of the adhesive layer 30 is 3 wt% or less, specifically 0.5 By weight to 1% by weight. If the content of the pressure-sensitive adhesive exceeds 3% by weight in the region exposed through the opening of the central portion 30b of the pressure-sensitive adhesive layer 30, the breathability of the waterproof breathable sheet may be deteriorated.

1, the end of the peripheral portion 30a of the adhesive layer 30 can be formed to coincide with the end of the nanomembrane 10, and the peripheral portion 30a of the adhesive layer 30 May extend beyond the end of the nanomembrane 10 to cover the end of the nanomembrane 10.

The adhesive layer 30 may include any one of a pressure sensitive adhesive selected from the group consisting of polyacryl, polyamide, polyacrylamide, polyester, polyolefin, polyurethane, polysilicon, Liquid type or solid type, and may be a thermoplastic type, a heat-converting type, or a reactive curing type.

On the other hand, the adhesive layer 30 may be a double-faced adhesive tape. The double-sided adhesive tape may be a double-sided adhesive tape made of polyethylene terephthalate (PET), a polypropylene-based double-sided adhesive tape, a polyethylene-based double-sided adhesive tape, a polyimide double-sided adhesive tape, a nylon- Foam, silicone foam, acrylic foam, polyethylene foam, etc.), double-sided adhesive tape without substrate,

The waterproof ventilation sheet 100 may further include a protective substrate (not shown) that protects the adhesive layer 30 before it is attached to the electronic apparatus.

The protective substrate may be made of a rubber or a silicone material, a polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate, a polyolefin such as polypropylene, polyethylene, or polymethylpentene, a resin material such as polycarbonate, A paper material such as a high-temperature paper, a coated paper, an impregnated paper, and a synthetic paper, and a metal foil material such as aluminum and stainless steel.

For the purpose of preventing electrification, a conductive material may be coated on the protective substrate as required, or a conductive material mixed with a conductive material may be used. As a result, the waterproof ventilation sheet 100 can be prevented from being charged. The thickness of the protective sheet may be, for example, 10 탆 to 100 탆, specifically, 25 탆 to 50 탆. A corona discharge treatment, a plasma treatment, a frame plasma treatment, or the like may be performed on the surface of the protective substrate in order to improve the adhesion with the adhesive layer 30, and a primer layer or the like may be formed. The primer layer may be any one selected from the group consisting of polyethylene, polypropylene, styrenic copolymer, polyester, polyurethane, polyvinyl alcohol, polyethyleneimine, polyacrylate, polymethacrylate, A polymer material (made of an anchor coat) can be used.

When the waterproof ventilation sheet 100 does not further include the adhesive layer 30, when the waterproof ventilation sheet 100 is attached to the housing of the electronic apparatus, the pressure sensitive air permeable sheet 100 or electronic The waterproof breathable sheet (1) can be applied to the housing of the apparatus by screen printing, spray coating, gravure printing, transfer, powder coating or the like by direct screen printing, spraying or ultrasonic welding without the pressure- 100 may be attached directly to the housing of the electronic device.

A method of manufacturing a waterproof breathable sheet according to another embodiment of the present invention includes the steps of preparing an electrospun solution, electrospinning the electrospun solution to form nanofibers, which are integrated into a nonwoven fabric including a plurality of pores, , And laminating the support to the nanomembrane. The waterproof breathable sheet produced by the method for producing a waterproof breathable sheet has a breathability of 1,000 mL / min or more at a pressure of 1 PSI.

First, the step of preparing the electrospinning solution is to prepare a solution containing a polymer for forming nanofibers through electrospinning. For example, the electrospinning solution may include polyvinylidene difluoride (PVdF) (N, N-dimethylacetamide), N, N-dimethyl formamide, dimethylsulphoxide, N-methyl-2-pyrolidone, triethyl phosphate may be prepared by mixing with any one solvent selected from the group consisting of triethylphosphate, methylethylketone, tetrahydrofuran, acetone, and mixtures thereof.

Next, the prepared electrospinning solution is electrospun to prepare a nanomembrane in which the nanofibers are integrated into a nonwoven fabric including a plurality of pores.

The electrospinning may be performed using the electrospinning apparatus shown in FIG. 3 is a schematic view of a nozzle-type electrospinning device. 3, the electrospinning is carried out by using a metering pump 2 in a solution tank 1 in which the electrospinning solution is stored, a plurality of nozzles 3 to which high voltage is applied by the high voltage generator 6, The electrospinning solution is fed to the electrospinning solution by the difference in electric energy between the nozzle 3 or the tip of the electrospinning unit and the accumulation unit 4, that is, the voltage difference. The formed jet is whipped and stretched by the electric field to become thinner and the solvent is vaporized so that solid fibers are accumulated in the integrated portion 4. [

At this time, the nozzle 3 or the nozzle is arranged in a multi-stage at regular intervals to facilitate stable electric field formation and solvent volatilization. The nanomembrane may be formed by stacking two or ten layers of the nanofibers according to the interval between the nozzles 3 or the nipping.

Meanwhile, by adjusting the microstructure of the nanomembrane by adjusting the electrospinning conditions, a waterproof ventilation sheet having excellent waterproofing and waterproofing properties and breathability can be manufactured.

The concentration of the electrospinning solution may be 5% to 35%, specifically 5% to 25%. The concentration means a percent concentration, and the percent concentration can be obtained as a percentage of the mass of the solute to the mass of the solution. For example, the concentration can be determined by dividing the mass of the polymer contained in the electrospinning solution by the mass of the solvent, and then multiplying by 100. If the concentration of the electrospinning solution is less than 5%, the polymer may not be produced due to the low content of the polymer, and may be injected into the beads. If the concentration exceeds 35%, the polymer may not be dissolved, The pressure may become high and leak or breakage of the solution may occur.

The viscosity of the electrospinning solution may be from 100 cP to 10,000 cP, specifically from 200 cP to 5,000 cP. The viscosity of the solution can be measured at a temperature of 23 DEG C by the KS M ISO 2555 method. If the viscosity of the electrospun solution is less than 100 cP, the viscosity may be too low to produce fibers and be injected onto the beads. If the viscosity of the electrospinning solution is more than 10,000 cP, jets may not be formed during the spinning process, There may be a problem that the defects of the membrane increase.

Further, the electrospinning condition may be a voltage of 0 kV to 100 kV, specifically 20 kV to 70 kV. If the voltage exceeds 100 kV, sparks may be generated in a region susceptible to insulation during the spinning process, resulting in damage to the product or transfer or peeling of the product to the transfer roll during transfer due to static electricity.

The electrospinning condition may be a discharge amount of 0.01 mL / min to 100 mL / min, specifically 0.5 mL / min to 50 mL / min. When the discharge amount is less than 0.01 mL / min, the amount of the laminated fibers is small, resulting in a decrease in productivity or delamination. When the discharge amount exceeds 100 mL / min, the saturation concentration of the solvent in the chamber increases, And there is a problem that the product is finally reused and filmed.

As described above, the nanomembrane may be formed by laminating two to ten layers of the nanofiber by the nozzle 3 or the multistage arrangement of the nipping, so that delamination of the nanofibers may occur. Accordingly, the method for manufacturing a waterproof breathable sheet according to an embodiment of the present invention is characterized in that the step of producing the nanomembrane and the step of bonding the support to the nanomembrane are performed by heat treating the nanomembrane at a temperature not lower than the melting initiation temperature of the nanofibers . The interlaminar peeling strength of the nanofibers can be improved through heat treatment at a temperature above the melting point start temperature of the nanofibers.

However, since the nanofiber prepared by electrospinning the PVdF can easily be damaged by pressure or external scratches, and the fiber phase tends to collapse and become a film, deterioration of air permeability may easily occur. Accordingly, it is preferable that the heat treatment of the nanomembrane is performed in a manner that the pressure is not applied or minimized. For example, the surface temperature of the hot roller may be fixed at the melting point initiation temperature of the nanofibers and the nanomembrane may be continuously passed along the surface of the hot roller.

The heat treatment temperature may be 110 ° C to 170 ° C, specifically 120 ° C to 150 ° C. If the heat treatment temperature is lower than 110 ° C, the interlayer peel strength of the nanomembrane is not improved and the layer can be easily separated. If the temperature is higher than 170 ° C, the fibers of the nanomembrane may melt, .

Finally, the support is joined to the nanomembrane to produce a waterproof ventilation sheet. The method of manufacturing the waterproof breathable sheet provides a method of minimizing the pressure in the process of laminating the nanofiber made of the nanofiber and the support to prevent the permeability of the nanofiber, which is sensitive to pressure, from deteriorating.

Specifically, a method of laminating the support to the nanomembrane according to one example may be performed by applying the moisture-curing hot-melt adhesive to the nanomembrane or the support using a gravure coater.

The roller of the gravure coater used in the gravure coater may include a dot or a mesh pattern on the surface in order to apply the adhesive so that the adhesive has a dot or mesh pattern.

The laminating speed of the gravure coater may be 1 m / min or more, specifically 5 m / min to 10 m / min. When the laminating speed of the gravure coater is less than 1 m / min, transfer of the adhesive becomes non-uniform, and the adhesive is excessively applied to a specific portion of the adhesion pattern, thereby lowering the air permeability of the nano-membrane and the support.

Further, in order to prevent the adhesive from leaking onto one surface of the nanomembrane or the support, it is possible to reduce the fluidity of the adhesive by using a separate interlayer film or by cooling the adhesive before winding. If the adhesive leaks out, the nanomembrane may be damaged during the inspection process to decrease water pressure, or the waterproof ventilation sheet may not satisfy the waterproofness.

Thereafter, the adhesive can be aged for at least one day in a maturing chamber having a temperature of 30 to 50 ° C and a humidity of 85% or more for moisture hardening of the adhesive.

The method of laminating the support to the nanomembrane according to another exemplary embodiment may be performed by spraying the soluble hot melt adhesive onto the nanomembrane or the support.

At this time, the spray rate may be 5 m / min or more, specifically 7 m / min to 10 m / min. When the spraying speed is less than 5 m / min, the transfer of the adhesive is made non-uniform, and the adhesive is excessively applied to a specific portion of the adhesive pattern, thereby decreasing the air permeability of the nano-membrane and the support.

The melting temperature of the hot-melt adhesive may be 90 ° C to 160 ° C, specifically 100 ° C to 120 ° C. When the melting temperature of the hot melt adhesive is less than 90 ° C, the adhesive may be remelted at a thermal shock temperature of the waterproof breathable sheet to block the pores of the nanomembrane, thereby deteriorating waterproof performance and air permeability. The pores of the nanomembrane may be clogged.

Specifically, the soluble hot melt is applied to the nanomembrane or the support by spraying through a nozzle or a nozzle which is sprayed after the adhesive is melted, and the nanomembrane is uniformly supplied to the upper surface of the support and wound. At this time, in order to prevent the adhesive from leaking out, the interlayer film may be inserted to co-wind or lower the fluidity of the adhesive in the cooling portion of the lower surface of the support, before winding.

The method of laminating the support to the nanomembrane according to another embodiment may be performed by melting and bonding at a temperature between the melting initiation temperature of the nanomembrane and the glass transition temperature of the support. That is, in this case, the adhesive is not used.

Specifically, the temperature is set between the glass transition temperature of the support and the melting initiation temperature of the nanomembrane by utilizing the thermal characteristics of the nanomembrane and the support, and the lamination is performed with a minimum pressure. For example, the glass transition temperature of the support containing the low melting point PET is 60 ° C to 70 ° C, and the melting point initiation temperature of the nanofibers prepared by electrospinning the PVdF is 125 ° C. At this time, the surface temperature of the joining hot rollers is fixed between the glass transition temperature of the support and the melting start temperature of the nano-web produced by electrospinning the PVdF. If the surface temperature of the hot roller is less than the glass transition temperature of the support (60 ° C to 70 ° C), adhesion may not be achieved, and the surface temperature of the hot roller is lower than the glass transition temperature If the temperature is higher than 125 ° C, the nanofiber nanofibers of the nanomembrane are collapsed and filmed so that air permeability may be drastically lowered.

In order to minimize damage to the nanofibers produced by electrospinning the PVdF, the pressure is preferably 10 kgf / cm or less, specifically 1 kgf / cm or less. If the pressure exceeds 10 kgf / cm, the nano-web produced by electrospinning the PVdF may be broken down into a film due to the pressure, and the air permeability may be lowered.

According to another embodiment of the present invention, a method of bonding the support to the nanomembrane may be performed by disposing a thermal bonding nonwoven fabric, which is a support on both sides of the nanomembrane, and heat-treating the same. That is, in this case, the adhesive is not used.

In particular, it is possible to bond the nanomembrane and the support through heat treatment at a temperature equal to or higher than the thermal bonding temperature of the thermal bonding nonwoven fabric. In this case, the thermal bonding nonwoven fabric is disposed on both surfaces of the nanomembrane, In order to maximize the adhesive force of the adhesive layer.

For example, the thermal bonding nonwoven fabric may include a first fiber made of a high melting point polyethylene terephthalate (PET) having a melting point of 240 ° C or higher and a second fiber made of a low melting point polyethylene terephthalate (PET) having a melting point of 120 ° C to 230 ° C. When the fiber is included, the surface temperature of the joining hot roller can be thermally bonded by fixing the melting start temperature of the low melting point polyethylene terephthalate and the melting point starting temperature of the nanoweb produced by electrospinning the PVdF. In order to minimize damage to the nanofibers produced by electrospinning the PVdF, the pressure is preferably 10 kgf / cm or less, specifically 1 kgf / cm or less. If the pressure exceeds 10 kgf / cm, the nano-web produced by electrospinning the PVdF may be broken down into a film due to the pressure, and the air permeability may be lowered.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[Production Example: Preparation of breathable waterproof sheet]

(Example 1)

An electrospinning solution was prepared by dissolving PVdF in dimethylacetamide at a concentration of 15% (w / w). The viscosity of the electrospinning solution was 2,100 cP.

The electrospinning solution was electrospun using the electrospinning device of FIG. 3 at a voltage of 60 kV and a discharge rate of 6.5 mL / min to prepare a nanomembrane.

The prepared nanomembrane had a pore size of 78%, an air permeability of 6.79 CFM, a water pressure of 6,500 mmH ₂ O, and nanofibers were stacked in five layers.

The prepared nanomembrane was heat-treated by fixing the surface temperature of the hot roller at 125 DEG C, which is the melting point start temperature of the nanofibers, and continuously passing the nanomembrane along the surface of the hot roller.

On the other hand, a thermal bond nonwoven fabric in which general PET and low melting point PET were mixed at a weight ratio of 50:50 was prepared as a support. The basis weight of the support was 30 g / m ² .

The prepared nanomembrane and the support were laminated with a moisture-curing hot-melt adhesive using a gravure coater and aged for 24 hours in an aging chamber having a humidity of 85% at 35 DEG C for moisture hardening of the adhesive. At this time, the moisture-curing hot-melt adhesive is polyurethane based, and a laminating speed of the gravure coater was 5 m / min, and the application amount of the adhesive was 5 g / m ^2, the pattern form of a mesh (mesh) of the rollers of the gravure coater Respectively.

The nano-membranes, the double-faced tape and the protective substrate laminated with the support were continuously introduced, and the lower surface of the double-sided tape was adhered to the upper surface of the nanomembrane and the protective substrate was laminated. Then, a waterproof breathable sheet was produced by passing through a mold having a constant pressure and speed and casting to a certain size.

(Example 2)

In the same manner as in Example 1, except that the mesh pattern of the hot-melt adhesive was placed at intervals of 5% to 25% of the circumferential length of the surface of the nanomembrane in Example 1, To prepare a waterproof ventilation sheet.

(Example 3)

A waterproof breathable sheet was prepared in the same manner as in Example 1 except that the laminating speed of the gravure coater was 10 m / min and the applied amount of the adhesive was changed to 6 g / m ² .

(Example 4)

In Example 1, a waterproof breathable sheet was prepared in the same manner as in Example 1, except that the prepared nanomembrane and the support were coated by spraying a soluble hot-melt adhesive.

At this time, the soluble hot melt adhesive was polyester-based, the spray rate was 15 m / min, the application amount of the adhesive was 5 g / m ² , and the melting temperature of the hot melt adhesive was 120 ° C.

(Example 5)

In the same manner as in Example 1, except that the nanomembrane and the support were melt-bonded at a temperature between the melting initiation temperature of the nanomembrane and the glass transition temperature of the support, To prepare a waterproof breathable sheet.

At this time, the surface temperature of the hot roller is fixed to 125 ° C, which is the melting point start temperature of the nanomembrane, and 100 ° C, which is a temperature between 60 ° C and 70 ° C, which is the glass transition temperature of the support. In order to minimize the damage of the nanomembrane The pressure was 0.7 kgf / cm.

(Example 6)

A thermally bonded nonwoven fabric in which general PET and low melting point PET were mixed as a support at a weight ratio of 50:50 was prepared as a support. The basis weight of the support was 15 g / m ² .

The thermal bonding nonwoven fabric was placed on both sides of the nanomembrane and heat treated at a temperature equal to or higher than the thermal bonding temperature of the thermal bonding nonwoven fabric to form the nanomembrane and the support without the adhesive. A waterproof breathable sheet was produced.

At this time, the surface temperature of the hot roller was 100 DEG C, and the pressure was set to 0.7 kgf / cm to minimize the damage of the nanomembrane.

(Comparative Example 1)

In Example 1, a waterproof breathable sheet was prepared in the same manner as in Example 1, except that the heat treatment of the nanomembrane was omitted.

(Comparative Example 2)

In Example 1, a waterproof breathable sheet was prepared in the same manner as in Example 1, except that a hot-melt adhesive was randomly applied to the nanomembrane.

(Comparative Example 3)

In Example 1, when the prepared nanomembrane and the support were laminated with a moisture-curing hot-melt adhesive using a gravure coater, the gravure coater's laminating speed was 1 m / min and the application amount of the adhesive was 8 g / m ² , and the roller of the gravure coater was formed in the same manner as in Example 1 except that no pattern was formed, thereby producing a waterproof breathable sheet.

[Experimental Example 1: SEM observation of nanomembrane]

The nanomembranes prepared in Example 1 and Comparative Example 1 were observed with a scanning electron microscope (SEM), and the results are shown in FIGS. 4 and 5, respectively.

Referring to FIGS. 4 and 5, it can be seen that the nanomembrane fabricated in Example 1 is formed with a fusion bonding portion of nanofibers through the heat treatment. However, the nanomembrane manufactured in Comparative Example 1 is not subjected to the heat treatment It can be confirmed that the fused joint of the nanofiber is not formed.

[Experimental Example 2: Measurement of delamination property of nanomembrane]

The interlaminar peel strengths of the nanomembranes prepared in Example 1 and Comparative Example 1 were measured and the results are shown in Table 1 below.

In Table 1, the porosity of the nanomembrane was measured according to Equation (2).

The air permeability was measured by an ASTM D 737 method under the conditions of an area of 38 cm 2 and a pressure of 125 Pa.

The water pressure of the nanomembrane was measured by applying pressure of 600 ㎜ H ₂ O / min at an area of 100 cm 2 by applying the ISO 811 low pressure method to measure the pressure at three points on the water droplet.

The interlaminar peel strength was measured by ASTM D 3330 method at a width of 25 mm, a length of 200 mm and a speed of 300 mm / min.

division	Porosity	Air permeability	Water pressure	Interlaminar peel strength
Example 1	70%	5.13 CFM	6,170 mm H 2 O	260.7 gf / 25 mm
Comparative Example 1	78%	6.79 CFM	6,500 mm H 2 O	23.0 gf / 25 mm

Referring to Table 1, it can be seen that the interlaminar peel strength of the nanomembrane of Example 1 was improved ten times or more by the heat treatment.

[Experimental Example 3: Measurement of properties of waterproof breathable sheet]

The properties of the waterproof breathable sheet prepared in the above Examples and Comparative Examples were measured, and the results are shown in Tables 2 and 3 below.

In Table 2, the peel strengths of the nanomembrane 10 and the support 20 were measured by ASTM D 3330 at a width of 25 mm, a length of 200 mm and a speed of 300 mm / min.

The rupture strength of the waterproof breathable sheet was measured five times with a Mullen type bursting strength tester satisfying ASTM D 3786 and expressed as an average value thereof.

The air permeability of the waterproof breathable sheet was measured by an ASTM D 737 method under the conditions of an area of 38 cm 2 and a pressure of 125 Pa.

The water pressure of the waterproof ventilation sheet was measured by applying pressure of 600 ㎜ H ₂ O / min at an area of 100 cm 2 by applying the ISO 811 low pressure method to measure the pressure at three points on the water drop.

division	Peel strength (nanomembrane and support)	Burst strength	Air permeability	Water pressure
Example 1	1,840 gf / 25 mm	4.4 kgf / cm2	4.2 CFM	4,500 mm H 2 O
Example 2	1,530 gf / 25 mm	4.5 kgf / cm2	4.9 CFM	4,800 mm H 2 O
Example 3	1,780 gf / 25 mm	4.1 kgf / cm2	4.0 CFM	4,100 mm H 2 O
Example 4	1,345 gf / 25 mm	4.5 kgf / cm2	4.5 CFM	3,400 mm H 2 O
Example 5	770 gf / 25 mm	4.3 kgf / cm2	4.8 CFM	4,120 mm H 2 O
Example 6	980 gf / 25 mm	1.9 kgf / cm2	3.9 CFM	3,900 mm H 2 O
Comparative Example 1	320 gf / 25 mm	4.0 kgf / cm2	4.3 CFM	2,800 mmH 2 O
Comparative Example 2	2,110 gf / 25 mm	4.7 kgf / cm2	3.7 CFM	2,500 mm H 2 O
Comparative Example 3	370 gf / 25 mm	4.8 kgf / cm2	3.5 CFM	2,400 mm H 2 O

In the following Table 3, the waterproofness of the waterproof breathable sheet was measured using a water pressure meter capable of applying a constant water pressure of 0 m to 20 m depth used in KS K ISO 811 for a predetermined time. In the case of the low temperature, the sample was pretreated at -20 ° C for 72 hours and then evaluated. After the pretreatment at 50 ° C and 95% humidity for 72 hours, the samples were evaluated at a temperature of -40 ° C and 85 ° C The air permeability of the waterproof breathable sheet was measured by measuring the permeability of the gas permeation of a capillary flow porometer (CFP) The gas permeability method was used to measure the flow rate of air passing through a 1 mm diameter circular area for 1 minute under 1 PSI pressure.

division	Breathability	Waterproof at room temperature	Low temperature waterproofing	High temperature / high humidity waterproof	Thermal shock resistance
Example 1	1,200 mL / min	2M Hold for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Example 2	1,670 ml / min	2M Hold for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Example 3	1,130 mL / min	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Example 4	1,520 mL / min	2M Hold for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Example 5	1,625 mL / min	2M Hold for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Example 6	1,150 mL / min	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes	1.5M Maintain for 30 minutes
Comparative Example 1	1,420 mL / min	1.5M 12 minute leak	1.5M 8 minute leak	1.5M 1 minute leak	1.5M 1 minute leak
Comparative Example 2	890 ml / min	1.5M 25 minute leak	1.5M three minute leak	1.5M 1 minute leak	1.5M 1 minute leak
Comparative Example 3	930 mL / min	1.5M 1 minute leak	1.5M 1 minute leak	1.5M 1 minute leak	1.5M 1 minute leak

Referring to the above Tables 2 and 3, it was found that, as in the case of Comparative Example 3, when a patternless gravure coater was used and the laminating speed of the gravure coater and the application amount of the adhesive exceeded the range of the present invention, As a result, there is a problem that the air permeability is lowered and the water pressure is lowered due to membrane damage caused by the abutting body.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments, but various modifications and changes may be made without departing from the scope of the invention. To those of ordinary skill in the art.

[Description of Symbols]

1: solution tank

2: metering pump

3: Nozzle

4:

6: High voltage generator

100: Waterproof ventilation sheet

10: nanomembrane

20: Support

30: Adhesive layer

30a: peripheral portion 30b: central portion

200: jig

210:

The present invention relates to a waterproof breathable sheet and a method of manufacturing the same, wherein the waterproof breathable sheet minimizes delamination of a nanofiber composed of nanofibers to maximize adhesion between the nanofiber and the adhesive layer, It is excellent in both waterproof property and air permeability by preventing decrease of air permeability due to pressure when laminating the support.

The waterproof ventilation sheet is used in various electronic apparatuses such as mobile apparatuses, electronic apparatuses such as hearing aids, communication apparatuses such as radio transmitters, automobile head lamps, and the like, thereby imparting air permeability to the electronic apparatuses, And waterproof to prevent penetration of water / liquid into the electronic device and dustproof to prevent contamination / dust penetration can be given to the electronic device.

Claims (20)

1. A nanomembrane in which nanofibers are laminated in the form of a nonwoven fabric including a plurality of pores, and

   And a support for supporting the nanomembrane,

   Waterproof breathable sheet with a breathability of at least 1,000 mL / min at a pressure of 1 PSI.
2. The method according to claim 1,

   Wherein the nanomembrane is formed by laminating two to ten layers of the nanofibers, and the interlaminar peeling strength of the nanofibers is 100 gf / 25 mm to 500 gf / 25 mm.
3. 3. The method of claim 2,

   Wherein the first layer and the second layer adjacent to each other of the nanofibers in the nanomembrane include a fusion bonding portion in which the nanofibers of the first layer and the nanofibers of the second layer are fusion- .
4. The method according to claim 1,

   Wherein the separation strength between the nanomembrane and the support is 500 gf / 25 mm to 2,000 gf / 25 mm.
5. The method according to claim 1,

   Wherein the waterproof ventilation sheet further comprises a moisture-curing hot-melt adhesive for bonding the nanomembrane and the support between the nanomembrane and the support,

   The adhesive has a pattern in the form of a dot or a mesh,

   Wherein the adhesive is applied in an amount of 6 g / m ² or less.
6. The method according to claim 1,

   Wherein the waterproof ventilation sheet further comprises a soluble hot melt adhesive between the nanomembrane and the support to bond the support to the nanomembrane,

   The adhesive has an irregularly distributed dot shape,

   Wherein the adhesive is applied in an amount of 6 g / m ² or less.
7. The method according to claim 1,

   Wherein the nanomembrane comprises a fused bond in which the nanofibers are fusion bonded to the support.
8. The method according to claim 1,

   The support is a thermal bonding nonwoven fabric,

   Wherein the support is located on both sides of the nanomembrane.
9. The method according to claim 1,

   The nanomembrane has an air permeability of 1 CFM to 20 CFM (cubic feet per minute)

   A waterproof breathable membrane the nano-sheet is not less than the water pressure 3,000 ㎜H ₂ O.
10. The method according to claim 1,

    The rupture strength of the waterproof breathable sheet is 0.5 kgf / cm 2 to 7 kgf / cm 2,

    Wherein the waterproof ventilation sheet has an air permeability of 0.5 CFM to 9 CFM,

    The waterproof breathable sheet is a water pressure is 3,000 ㎜H ₂ O to 12,000 ㎜H ₂ O,

    The waterproof breathable sheet has a water repellency grade of 4 or more,

    The waterproof ventilation sheet has waterproofness and waterproof properties under a high temperature / high humidity condition (50 DEG C, 95% humidity and 72 hours of keeping) at a normal temperature condition (20 DEG C and 5 DEG C) (Measured after repeating one cycle of maintaining one cycle of -40 deg. C and 85 deg. C for 1 hour respectively), and no water leaks at a water pressure of 1.5 m or more for 30 minutes or more.
11. The method according to claim 1,

    Wherein the nanofiber is made of polyvinylidene difluoride (PVdF).
12. The method according to claim 1,

    Wherein the support is a polyester spun bonding or a thermal bonding nonwoven fabric.
13. The method according to claim 1,

    Wherein the waterproof breathable sheet further comprises an adhesive layer on one surface of the nanomembrane.
14. Preparing an electrospinning solution,

    Preparing a nanomembrane in which the nanofibers are integrated into a nonwoven fabric including a plurality of pores by electrospinning the prepared electrospinning solution, and

    And laminating a support to the nanomembrane,

    Wherein the air permeability is 1,000 mL / min or more at a pressure of 1 PSI.
15. 15. The method of claim 14,

    Between the step of preparing the nanomembrane and the step of laminating the support,

    And heat treating the nanomembrane at a temperature not lower than a melting initiation temperature of the nanofibers.
16. 16. The method of claim 15,

    Wherein the heat treatment temperature in the heat treatment step is 110 to 170 ° C.
17. 15. The method of claim 14,

    Wherein the step of laminating the support is performed by applying a moisture-curing hot-melt adhesive to the nano-membrane or the support using a gravure coater.
18. 15. The method of claim 14,

    Wherein the step of laminating the support comprises applying an aqueous hot melt adhesive to the nanomembrane or the support by spraying.
19. 15. The method of claim 14,

    Wherein the step of laminating the support is to melt-adhere the nanofibers of the nanomembrane at a temperature between a melting initiation temperature of the nanomembrane and a glass transition temperature of the support.
20. 15. The method of claim 14,

    Wherein the step of laminating the support comprises arranging a thermal bonding nonwoven fabric, which is a support on both sides of the nanomembrane, and thermally bonding the support.

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