KR101812789B1 - Waterproof ventilation sheet and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a waterproof ventilation sheet and a manufacturing method thereof. The waterproof ventilation sheet includes a nanomembrane integrated in a nonwoven form in which nanofibers include a plurality of pores. In the nanomembrane, anisotropy (MD elastic modulus/TD elastic modulus) between a length direction (machine direction (MD)) elastic modulus and a width direction (transverse direction (TD)) elastic modulus is 1.5 to 10.0. The waterproof ventilation sheet has a water pressure waterproof ability which does not leak for more than 30 minutes at a water pressure of 1.5 m or more at room temperature (20C 5C), wherein acoustic transmission loss is less than 10 dB at 1000 Hz. The waterproof ventilation sheet: eliminates distortion of sound by suppressing sound absorption and diffusion reflection and lowering an absorption coefficient by controlling the microstructure of nanofibers of a nanomembrane and especially the orientation of nanofibers; and improves resistance to water pressure by increasing resistance against pressure deformation due to water pressure applied during resistance to the water pressure by improving the elastic modulus and strength of the nanomembrane.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a waterproof breathable sheet,

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 absorption and diffuse reflection of sound by controlling the microstructure of the nanofiber, To a waterproof breathable sheet in which distortion of sound is eliminated by lowering the coefficient, and a method of 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.

Particularly, electronic devices such as mobile devices have various performance and functions, and thus frequency of use has been increased. As a result, not only waterproof / dustproof functions in various environments, but also acoustic performance Are also required.

It is an object of the present invention to suppress the absorption and diffusing of sound by suppressing the negative and diffuse reflection and to suppress the distortion of sound by controlling the microstructure of the nanofiber of the nanofiber, particularly the nanofiber, And a waterproof breathable sheet having improved resistance to pressure deformation due to water pressure applied at the time of water pressure resistance and improved water pressure.

Another object of the present invention is to provide a waterproof ventilation sheet having excellent water permeability and excellent waterproofing and breathability by unidirectionally orienting the nanofiber prepared by electrospinning by polyvinylidene fluoride electrospinning And a method of manufacturing a waterproof breathable sheet capable of enhancing stability and usability in a roll-to-roll process.

According to an embodiment of the present invention, the nanofibers include a nanomembrane integrated into a nonwoven fabric including a plurality of pores, wherein the nanomembrane has a machine direction (MD) modulus and a transverse direction (TD) ) A waterproof breathable sheet having an anisotropy of elastic modulus (MD elastic modulus / TD elastic modulus) of 1.5 to 10.0. The waterproof ventilation sheet has a waterproofing waterproofing property that does not leak at normal temperature (20 ° C ± 5 ° C), a water pressure of 1.5 m or more for 30 minutes or more, and an acoustic transmission loss of less than 10 dB at 1000 Hz.

Wherein the nanomembrane has a shape with an aspect ratio (SD: LD) of 2 to 50 of the smallest diameter (SD) of the pore with respect to a longest diameter (LD) of the pore, A long diameter (LD) can be oriented in a direction parallel to the longitudinal direction of the nanomembrane.

The nano-membrane may have an absorption coefficient of the nanomembrane of less than 0.2 at 1000 Hz and an acoustic transmission loss of less than 10 dB at 1000 Hz due to the anisotropy of the longitudinal and lateral moduli.

Wherein the nanofiber has a diameter of 50 nm to 3000 nm, a thickness of 3 占 퐉 to 40 占 퐉, a pore size of 0.1 占 퐉 to 5 占 퐉, a porosity of 40% to 90%, an air permeability of 0.1 CFM To 20 CFM, a water pressure of 3000 mmH ₂ O or more, a water repellency grade of 4 or more, an elastic modulus of 1 MPa to 1000 MPa, and a basis weight of 0.5 g / m 2 to 20 g / m 2.

The waterproof ventilation sheet was subjected to high temperature / high humidity conditions (50 DEG C, 95% humidity, 72 hours, no water leaks for at least 30 minutes at a water pressure of 1.5 m or more in the case of waterproof waterproof property at low temperature (Measured after repeating 30 cycles of one cycle maintaining -40 ° C and 85 ° C for 1 hour respectively) without leaking at a water pressure of 1.5 m or more for 30 minutes or more and 1.5 m or more It may not be leaked for over 30 minutes under water pressure.

The waterproof breathable sheet may have a breathability of at least 20 cc / min (@ 1 PSI).

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

The waterproof breathable sheet may further include an adhesive layer on one side or both sides 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; And uniaxially orienting the nanomembrane. The present invention also provides a method of manufacturing a waterproof breathable sheet.

The uniaxial orientation of the nanomembrane may be performed by applying a tensile force of 1.5 to 20 times the longitudinal direction of the nanomembrane as compared to the width direction of the nanomembrane.

The uniaxial orientation of the nanomembrane may be controlled by controlling the winding speed of the nanomembrane to 0.01 m / min to 20 m / min and the TR (traverse) rate to 0.001 m / min to 10 m / min .

The waterproof breathable sheet of the present invention controls the microstructure of the nanofiber of the nanomembrane, in particular, the orientation of the nanofiber, thereby suppressing sound absorption and diffusing reflection, lowering the sound absorption coefficient to eliminate sound distortion, The strength is improved, resistance to pressure deformation due to water pressure applied at the time of water pressure increase, and water pressure is improved.

In addition, the method for producing a waterproof breathable sheet of the present invention is manufactured by electrospinning polyvinylidene fluoride. In this case, the electrospun nanomembrane is uniaxially oriented to have excellent voicing and waterproofness and water permeability It is possible to manufacture an excellent waterproof ventilation sheet and to enhance stability and usability in a roll-to-roll process.

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 and 5 are scanning electron microscope (SEM) photographs of the nanomembranes prepared in Example 1 and Comparative Example 1 of the present invention, respectively.

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 integrated into a nonwoven fabric including a plurality of pores. The nanomembrane has a machine direction (MD) modulus and a transverse direction, TD) is anisotropy (MD elastic modulus / TD elastic modulus) of the elastic modulus is 1.5 to 10.0. The waterproof ventilation sheet has a waterproofing waterproofing property that does not leak at normal temperature (20 ° C ± 5 ° C), a water pressure of 1.5 m or more for 30 minutes or more, and an acoustic transmission loss of less than 10 dB at 1000 Hz.

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 ventilation sheet 100 includes a nanomembrane 10 in which nanofibers are integrated in the form of a nonwoven fabric including a plurality of pores, and, optionally, one or both surfaces of the nanomembrane 10 And may further include an adhesive layer 20. 1, the waterproof ventilation sheet 100 may further include a support (not shown) for supporting 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 20 is located only on one surface of the nanomembrane 10, but the present invention is not limited thereto. The adhesive layer 20 may be formed on the surface of the nanomembrane 10, As shown in FIG.

The nanomembrane 10 has a porous structure formed by the nanofibers to prevent foreign matter such as water or dust from passing therethrough and permeate the gas. In addition, the nanomembrane 10 allows passage of sound. Therefore, the waterproof ventilation sheet 100 is, for example, an electronic device having a sounding portion or a sound receiving portion, which is disposed in the ventilation hole of the housing corresponding to the sounding portion or the sound receiving portion, And can be used for ensuring dustproofness.

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 passage of time and heat, the waterproof breathable sheet 100 shrinks and the adhesive layer 20 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 may have a poor sound absorption due to the regularly oriented / laminated nanofibers constituting the nanofibers, because the pores in the fiber are circular or polygonal, and the absorption coefficient is high. In the present invention, the PVdF is electrospun to fix the orientation of the nano-web in the uniaxial direction when manufacturing the nano-web to control the microstructure of the nanofiber, in particular, the orientation of the nanofiber, thereby suppressing sound absorption and diffuse reflection, Lowering the distortion of the sound.

Specifically, conventionally, the orientation of the nanofibers in the nanowire fabricated by electrospinning PVdF is substantially equal in the longitudinal direction (MD) and the transverse direction (TD). However, cavities are generated by the uniform fiber orientation of the nanofibers, and when the acoustic waves pass through the cavities, sound absorption and diffuse reflection occur, resulting in distorted sound. In addition, the conventional nanomembrane can not satisfy the water pressure (1500 mmH ₂ O) required by the IPX 68 class by the cavity, and the water pressure standard can be attained by adding an additive such as a water repellent. However, water resistance can be improved by adding an additive such as the water repellent agent, but defects may occur during spinning, or adhesiveness between fibers may be insufficient, resulting in deterioration of handling properties.

However, if the orientation of the nanofibers is fixed in the uniaxial direction as in the present invention, the pores in the fibers become closer to the shape of a circle rather than a circular or polygonal shape, thereby reducing the overall number of pores, By suppressing irregular reflection, the sound absorption coefficient is lowered, and the sound performance is improved. At this time, since the orientation of the nanofibers is uniaxially fixed, the longest diameter of the linear pores is oriented in a direction substantially parallel to the longitudinal direction of the nanomembrane 10.

At this time, the linear pores have an aspect ratio (SD: LD) of the smallest diameter (SD) of the pores with respect to the longest diameter (LD) of the pores is 1: 2 to 1:50, : 5 to 1:50. When the aspect ratio (SD: LD) of the smallest diameter (SD) of the pores with respect to the longest diameter (LD) of the pores is less than 1: 2, pores are uniformly distributed and diffuse reflection occurs, If it exceeds 1:50, the pore may be deformed by the pressure such as water pressure or air pressure, and the waterproof performance or dustproof performance may be deteriorated.

As described above, as the orientation of the nanofiber is fixed in the uniaxial direction, the nanomembrane has an anisotropy (MD elastic modulus / TD elastic modulus) in a machine direction (MD) and a transverse direction (TD) 1.5 to 10.0, and more specifically 2.0 to 10.0. When the anisotropy (MD elastic modulus / TD elastic modulus) of the longitudinal direction elastic modulus and the lateral modulus of elasticity of the nanomembrane is 1.5 To 10.0, the condition that the acoustic transmission loss of the waterproof breathable sheet is less than 10 dB at 1000 Hz can be satisfied, and the water pressure (1500 mmH ₂ O) required by the IPX 68 class can be satisfied. The modulus of elasticity of the nanomembrane 10 may be determined by measuring the MD (Machine Direction) and the TD (Transverse Direction) ten times after applying ASTM D 882 and using the average value excluding the maximum value and the minimum value. The longitudinal direction or the machine direction (MD) of the nanomembrane is a length of the nanomembrane in the direction of movement of the roll when the nanomembrane is continuously produced in a roll-to-roll manner or in a direction in which the produced nanomembrane is wound, And the width direction of the nanomembrane or the transverse direction TD of the machine direction means a width direction in which the length is short in the longitudinal direction or the machine direction.

As described above, the orientation coefficient of the nanofiber 10 is uniaxially fixed or the anisotropy of the longitudinal direction elastic modulus of the nanomembrane 10 and the anisotropy of the lateral direction elastic modulus of the nanomembrane 10 is 1000 Hz And may be 0 to 0.1 at 1000 Hz, and the acoustic transmission loss of the nanomembrane 10 may be less than 10 dB at 1000 Hz, and specifically between 0 dB and 5 dB at 1000 Hz . In this case, the sound absorption coefficient can be measured by an in-pipe method sound absorption test (ASTM E 1050-12), the unit thereof is a constant, and the sound transmission loss is measured by a test method of ASTM E-2611-09 Transmission loss can be measured, and the measurement frequency band is 100 Hz to 5000 Hz at a 1/3 octave band center frequency. When the absorption coefficient of the nanomembrane 10 is 0.2 or more at 1000 Hz, or when the acoustic transmission loss is 10 dB or more at 1000 Hz, the sound insulation effect may occur, and the functionality may be deteriorated due to loss or distortion of sound. Accordingly, the acoustic transmission loss of the waterproof breathable sheet 100 may be less than 10 dB at 1000 Hz.

In addition, by fixing the orientation of the nanofibers in the uniaxial direction, the elastic modulus and strength in the longitudinal direction of the nanomembrane 10 are improved, and resistance to pressure deformation due to water pressure applied during water pressure is increased, 10 can be improved.

On the other hand, by controlling the electrospinning conditions during the production of nanofibers by electrospinning the PVdF, the air permeability of the nanomembrane 10 and the size distribution of the pores are controlled, thereby suppressing sound absorption and diffuse reflection, So that it is possible to have a better voice.

The nanomembrane 10 may have a diameter ranging from 50 nm to 3000 nm, more specifically from 100 nm to 2000 nm, and the thickness of the nanomembrane 10 ranges from 3 탆 to 40 탆. 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 and pore distribution of the nanomembrane 10 were measured using a capillary flow porometer (CFP) as defined in ASTM F316 to determine the average pore size and the pore size at the diameter of the limiting pore in the narrowest interval The size distribution of the pores 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 (1). The total volume can be obtained by measuring the width, length, and thickness of a rectangular or circular sample, 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.

[Equation 1]

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)

As described above, when the diameter of the nanofiber composing the nanomembrane 10 and the thickness, pore size, and pore distribution of the nanomembrane 10 are within the above ranges, the absorption of the nanomembrane 10 and the diffuse reflection It is possible to further reduce the distortion of the sound by lowering the sound absorption coefficient.

More specifically, the nanomembrane 10 is advantageous in that the nanofibers are irregularly oriented and laminated so that the size distribution of the pores is irregular, thereby suppressing the negative absorption and the diffuse reflection, thereby lowering the absorption coefficient. Specifically, When the size distribution of the nanomembrane 10 is 100/100 or more, the size distribution of the pores is larger than that of the nanomembrane 10 (cm < ² >). The size distribution of the pores is more irregularly arranged when the probability of finding pores having a pore size difference of 100 nm to 3900 nm per unit area (cm ² ) of 10/100 to 90/100 is more irregularly arranged, Absorption and diffuse reflection can be suppressed as much as possible. As described above, the acoustic transmission loss of the nanomembrane 10 may be less than 10 dB at 1000 Hz depending on whether the nanofibers are irregularly oriented and laminated and the size distribution of the pores is irregular, Hz to 0 dB to 5 dB.

Here, the unit area of the nanomembrane 10 measuring the size distribution of the pores may be any surface of the nanomembrane 10, specifically, both surfaces of the membrane, or an internal cross-section that is exposed by cutting the membrane , Preferably a unit area randomly selected from both surfaces of the membrane. The difference in size of the pores is a value obtained by subtracting the size of the smaller pores from the size of the larger pores among the two pores arbitrarily selected within the unit area. The probability means the number of times when the size difference of the pore is found within the range when the size difference of the pores is measured 100 times within the unit area.

Also, as the nanomembrane 10 includes the nanoweb fabricated by electrospinning the PVdF, the nanomembrane 10 may have an air permeability of 0.1 CFM to 20 CFM, specifically 0.5 CFM to 10 CFM Lt; / RTI > The air permeability of the nanomembrane can be measured under the conditions of an area of 38 cm 2 and a static pressure of 125 Pa by applying the ASTM D 737 method. In this case, ㎤ / ㎠ / s can be converted into CFM, the conversion coefficient is 0.508016, and the unit is ft ³ / ft ² / min (CFM). If the air permeability of the nanomembrane 10 is less than 0.1 CFM, the permeability of sound may be lowered and the acoustic performance may be deteriorated. If the air permeability exceeds 20 CFM, the water pressure may be lowered and water may penetrate into the electronic device, .

In addition, since the nanomembrane 10 includes a nanoweb fabricated by electrospinning the PVdF, the nanomembrane 10 has a water pressure of 3000 mmH ₂ O or more, specifically, a water pressure of 5000 mmH ₂ O to 20000 ㎜H may be a O _2. The water pressure of the nanomembrane ₁₀ can be measured at a point of 3 points on the water droplet by applying a pressure of 600 ㎜ H ₂ O / min at an area of 100 cm 2 by applying the KS K ISO 811 low pressure method.

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 . 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, the nanomembrane may be wetted due to hydrophilicity with water, or water may penetrate to lower the water pressure, thereby deteriorating the waterproof performance.

The nanomembrane 10 may have a modulus of elasticity ranging from 1 MPa to 1000 MPa and a specific elastic modulus ranging from 5 MPa to 500 MPa . The modulus of elasticity of the nanomembrane 10 may be determined by measuring the MD (Machine Direction) and the TD (Transverse Direction) ten times after applying ASTM D 882 and using the average value excluding the maximum value and the minimum value. If the elastic modulus of the nanomembrane 10 is less than 1 MPa, it may be easily deformed by an external stimulus or an impact to reduce the dust / waterproof performance or sound distortion. If the elastic modulus of the nanomembrane 10 exceeds 1000 MPa, Defects such as cutting (punching) and deformation may occur.

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 predetermined 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.

(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 for 30 minutes or more and a low temperature condition , It does not leak more than 30 minutes at a water pressure of 1.5 m or more, more specifically 30 minutes or more at a water pressure of 1.5 m to 6 m, 1.5 m at a high temperature / high humidity condition (50 ° C, 95% (Measured after repeating 30 cycles of maintaining a temperature of -40 ° C and 85 ° C for 1 hour, respectively) without leaking at a water pressure of 30 minutes or more, specifically, a water pressure of 1.5 m to 6 m for 30 minutes or more It may have a waterproofing waterproof property that does not leak 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. When the waterproofing ventilation sheet 100 is waterproofed at room temperature (20 ° C ± 5 ° C), water pressure of 1.5 m or more, water pressure of 1.5 m or less at low temperature, water pressure of 1.5 m or more at high temperature / Water or moisture may penetrate into the waterproofing ventilation sheet 100 and the electronic equipment may be damaged.

For reference, the water pressure at the certain depth can be calculated by the following equation (2), and the water pressure in the ocean increases by 1 atmospheres every time the water depth drops by 10 m.

&Quot; (2) "

Water pressure (p) = pgz

(In Equation 2, 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 have a breathability of 20 cc / min or more, specifically 20 cc / min to 150 cc / min, as the inclusion of the nanomembrane 10. 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 20 cc / min, air permeability is lowered to cause distortion of sound, or heat emission from an APU (Accelerated Processing Unit), a display or a BLU (Back Light Unit) .

The adhesive layer 20 is located on the surface of the nanomembrane 10 and specifically the periphery 20a of the adhesive layer 20 is located on the periphery of the surface of the nanomembrane 10, The central portion 20b of the layer 20 may be in the form of an open frame. The nanomembrane 10 is adhered to the inner surface of the vent hole of the housing of the electronic apparatus through the adhesive layer 20 and the vent hole of the housing of the electronic apparatus through the opening of the central portion 20b of the adhesive layer 20 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 20b of the adhesive layer 20 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 aperture 20a may be circular, oval, Rectangular, polygonal, P-shaped, and the like, but the present invention is not limited thereto.

1, the end of the peripheral portion 20a of the adhesive layer 20 may be formed to coincide with the end of the nanomembrane 10, and the peripheral portion 20a of the adhesive layer 20 May extend beyond the end of the nanomembrane 10 to cover the end of the nanomembrane 10.

The adhesive layer 20 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 20 may be a double-sided 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 can protect the adhesive layer 20 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. The surface of the protective substrate may be subjected to a corona discharge treatment, a plasma treatment, a frame plasma treatment, or the like to improve adhesion with the adhesive layer 20, 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 20, 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.

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

The support may be made of a material having a pore size larger than that of the nanomembrane 10 and having excellent gas permeability and excellent strength such as woven fabric, nonwoven fabric, mesh, net, sponge, foam, metal porous material, metal mesh, have. When heat resistance is required, a support made of a polyester, a polyamide, an aramid resin, a polyimide, a polyetherimide, a polyamideimide, a polyether sulfone, a fluororesin, an ultrahigh molecular weight polyethylene, a metal and the like can be used.

Specifically, the nonwoven fabric may be interlaid with the supporting body formed of a plurality of randomly oriented fibers. The nonwoven fabric may be interlaid, but may have a structure of individual fibers or filaments Sheet. 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 polymer materials, and any of those generally used as a fiber-forming polymer material may be used, and specifically, a hydrocarbon-based fiber-forming polymer material may 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.

In addition, the method of laminating the support on the nanomembrane 10 may be simply performed by overlapping or bonding. For example, the bonding may be performed by a method such as adhesive lamination, thermal lamination, thermal vapor deposition, ultrasonic vapor deposition, or adhesion by a pressure sensitive adhesive. For example, when the support is laminated with the nanomembrane 10 by thermal lamination, a part of the support may be melted and adhered by heating. In this case, the supporter adheres to the nanomembrane 10 without using a pressure-sensitive adhesive, and unnecessary weight increase and decrease in air permeability can be avoided. In addition, the support and the nanomembrane 10 may be adhered using a fusion agent such as hot melt powder.

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 uniaxially orienting the nanomembrane.

The method of manufacturing the waterproof breathable sheet can produce a waterproof breathable sheet having excellent water permeability and waterproofness and water permeability by uniaxially orienting the nano-membrane, and can enhance stability and usability in the roll-to-roll process.

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, by regulating the micro-structure of the nanomembrane by controlling the electrospinning condition, it is possible to produce a waterproof ventilation sheet having excellent water permeability and excellent waterproofing and waterproofing properties.

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 may be obtained by dividing the mass of the polymer contained in the electrospinning solution by the mass of the solution, 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 100 cP to 10000 cP, specifically 200 cP to 5000 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 electrospinning solution is less than 100 cP, the viscosity may be too low to produce fibers and may be injected onto the beads. If the viscosity exceeds 10000 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 rate of 0.01 cc / min to 100 cc / min, specifically 0.5 cc / min to 50 cc / min. When the discharge amount is less than 0.01 cc / min, the amount of the laminated fibers is small, resulting in a decrease in productivity or delamination. When the discharge amount exceeds 100 cc / min, the saturation concentration of the solvent in the chamber increases, And there is a problem that the product is finally reused and filmed.

Finally, the prepared nanomembrane is uniaxially oriented.

When the nanomembrane is uniaxially oriented, it is possible to control the orientation of the nanofibers to suppress sound absorption and diffuse reflection, and to lower a sound absorption coefficient to eliminate sound distortion. In addition, the uniaxial orientation of the nanomembrane can increase the tensile strength and elastic modulus in the longitudinal direction (MD) of the nanomembrane. Through this, the stability and usability in the in-line traveling during the roll-to-roll (R2R) process can be improved and the product yield can be increased. In addition, quality control can be stabilized by reducing deviation between existing lots (LOT).

Specifically, the uniaxial orientation of the nanomembrane may be performed by applying a tensile force of 1.5 to 20 times in the longitudinal direction to the width direction of the nanomembrane, and specifically applying a tensile force of 2 to 10 times . If the tensile force in the longitudinal direction is less than 1.5 times the tension in the width direction of the nanomembrane, anisotropy may not be imparted, isotropic properties are developed, negative absorption and diffuse reflection occur, and negative distortion may occur. If it is more than 20 times, the aggregation, strength and elongation modulus of the fibers may be lowered, resulting in breakage or tearing at the time of winding, resulting in deterioration of stability and usability. At this time, when the tensile force is applied only to the MD in the uniaxial orientation of the nanomembrane, and when the tensile force is not applied to the TD, i.e., when the tensile force applied to the TD is negative or zero, the width of the nanomembrane is reduced, The width of both sides of the nanomembrane should be at least fixed. In this case, the tensile force may be applied to the nanomembrane. Of course, in the present invention, uniaxial orientation can also be achieved by applying a tensile force only to the MD and applying a tensile force to the TD.

The method of uniaxially orienting the nanomembrane is not particularly limited in the present invention, and any method can be applied as long as it is conventionally a method of orienting a nanomembrane. For example, the uniaxial orientation may be achieved by a separate orientation device, and the integration condition of the integrated portion 4 may be adjusted in the electrospinning device, and the winding condition of the winding roller for winding the manufactured nanomembrane may be adjusted .

More specifically, for example, in the uniaxial orientation of the nanomembrane, the winding speed of the nanomembrane is adjusted to 0.01 m / min to 20 m / min, specifically 0.1 m / min to 10 m / min, and TR ( traverse speed from 0.001 m / min to 10 m / min, specifically from 0.01 m / min to 2 m / min. The TR speed means a speed at which the nanomembrane reciprocates in a direction perpendicular to the uniaxial orientation of the fiber, that is, in the width direction (TD). The nanomembrane may reciprocate the nanomembrane in the transverse direction (TD) during the electrospinning or the winding according to various reasons such as the uniform integration of the nanofibers irrespective of the position of the nozzle. When the winding speed and the TR speed are within the above range, an anisotropy (MD elastic modulus / TD elastic modulus) of the longitudinal elastic modulus and the width modulus of 1.5 to 10.0 can be produced.

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 18% (w / w). The viscosity of the electrospinning solution was 3000 cP.

The electrospinning solution was electrospun using the electrospinning device of FIG. 3 under the conditions of a voltage of 60 kV and a discharge rate of 20 cc / min to prepare a nanomembrane.

At this time, the nanomembrane was uniaxially stretched in the machine direction by adjusting the winding speed of the nanomembrane to 5.0 m / min and controlling the TR speed to 0.8 m / min.

The nano-membrane, the double-sided tape and the protective substrate were continuously introduced to adhere the lower surface of the double-sided tape to the upper surface of the nanomembrane, and the protective substrate was joined. Then, a waterproof breathable sheet was prepared by passing through a mold having a constant pressure and speed and cut to a certain size.

(Examples 2 to 3)

A waterproof breathable sheet was prepared in the same manner as in Example 1 except that the preparation conditions of the nanomembrane in Example 1 were changed as shown in Table 1 below.

(Comparative Example 1)

A waterproof breathable sheet was prepared in the same manner as in Example 1 except that the biaxial orientation of the nanomembrane was controlled by controlling the ratio of the winding speed of the nanomembrane to the TR speed to 1.05: 1.0.

division density(%) Viscosity (cP) Voltage (kV) Discharge amount (cc / min) Orientation ratio
(Winding speed / TR speed) Example 1 18 3000 60 20 6.25 Example 2 13 1000 55 20 7.75 Example 3 10 800 70 50 10.25 Comparative Example 1 35 12000 85 0.01 1.05

[Experimental Example 1: Observation of shape of nanomembrane]

Scanning electron microscope (SEM) photographs of the nanomembranes prepared in Example 1 and Comparative Example 1 are shown in FIGS. 4 and 5, respectively.

4 and 5, the pores of the nanomembrane prepared in Example 1 have an aspect ratio SD (SD: LD) of the smallest diameter (SD) of the pore to the longest diameter ) Is in the range of 1: 2 to 1:50, and the longest diameter (LD) of the pores is oriented in a direction parallel to the longitudinal direction of the nanomembrane.

On the other hand, the pores of the nanomembrane prepared in Comparative Example 1 have an aspect ratio (SD: LD) of the smallest diameter (SD) of the pores with respect to the longest diameter (LD) of the pores of 1: 1.5, and it can be observed that the longest diameter (LD) of the pores is randomly oriented.

[Experimental Example 2: Characterization of Nanomembrane]

The thickness, the basis weight, the longitudinal direction elastic modulus, the lateral direction elastic modulus and anisotropy of the nanomembrane prepared in the above Examples and Comparative Examples were measured and shown in Table 2 below, and the air permeability, water pressure, porosity, water repellency, The absorption coefficient was measured and is shown in Table 3 below.

The thickness of the nanomembrane was measured by the thickness measurement method specified in KS K 0506 or KS K ISO 9073-2, ISO 4593.

The basis weight of the nanomembrane was measured by applying ASTM D 3776.

The modulus of elasticity of the nanomembrane was measured by measuring the machine direction (MD) and the transverse direction (TD) 10 times using ASTM D 882, and the average value except for the maximum value and the minimum value was used.

The air permeability of the nanomembrane was measured using an ASTM D 737 method under the conditions of an area of 38 cm 2 and a static pressure of 125 Pa. The ㎤ / ㎠ / s were calculated as ^{ft 3 / ft 2 / min (} CFM). The conversion factor is 0.508016.

The water pressure of the nanomembrane was measured by applying pressure of 600 ㎜ H ₂ O / min at an area of 100 ㎠ by applying the KS K ISO 811 low pressure method to measure the pressure at three points on the water drop.

The porosity of the nanomembrane was measured according to Equation (1).

The water repellency of the nanomembrane was measured by the method described in KS K 0590.

The sound absorption coefficient was measured by an in-line method sound absorption test (ASTM E 1050-12).

division thickness
(탆) weight
(g / m 2) Elastic modulus
(MD, MPa) Elastic modulus
(TD, MPa) Anisotropy (MD / TD) Orientation Example 1 20 6.27 194 31.5 6.2 spurn Example 2 35 13 220 26 8.5 spurn Example 3 18 6.0 65 8.9 7.3 spurn Comparative Example 1 35 25 67 62 1.1 Binocular

division Air permeability
(CFM) Water pressure
(㎜H ₂ O) Porosity
(%) Water repellency Absorption coefficient Example 1 7.01 5,600 83 4-5 0.01 Example 2 6.87 5,270 80 4th grade 0.08 Example 3 3.04 12,820 81 5th grade 0.02 Comparative Example 1 9.01 1,450 60 1st grade 0.32

Referring to Tables 2 and 3, it can be seen that Examples 1 to 3 lowered the absorption coefficient by controlling the microstructure of the nanofiber nanofibers, particularly the orientation of the nanofibers.

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

The acoustic permeation loss, waterproofness (normal temperature, low temperature, high temperature / high humidity, thermal shock) and air permeability of the waterproof breathable sheet produced in the above Examples and Comparative Examples were measured and shown in Table 4 below.

The acoustic transmission loss of the waterproof breathable sheet was evaluated by the acoustic transmission loss test. Specifically, the acoustic transmission loss was evaluated by applying ASTM E 2611-09.

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 Were kept for 1 hour, respectively, and the cycle was repeated 30 times and then evaluated under the conditions of room temperature (20 DEG C +/- 5 DEG C).

The air permeability of the waterproof ventilation sheet was measured by a gas permeability method of 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.

division Acoustic transmission loss
(dB) Waterproof waterproof
(Room temperature) Waterproof waterproof
(Low temperature) Water pressure (high temperature and high humidity) Waterproof waterproof
(Thermal shock) Air permeability (cc / min @ 1PSI) Example 1 2 4m, 50 min 4m, 50 min 4m, 45 minutes 4m, 45 minutes 120 Example 2 3 4m, 80 min 4m, 75mins 4m, 60 minutes 4m, 60 minutes 100 Example 3 0.1 6 m, 300 min 6 m, 300 min 6m, 250 min 6m, 280m 80 Comparative Example 1 10 1.5m, 3 minutes 1.5m, 3 minutes 1.5m, 1 minute 1.5m, 2 minutes 160

In the above Examples 1 to 3, the acoustic transmission loss was less than 10 dB, the waterproofing waterproof property (normal temperature, low temperature, high temperature / high humidity, thermal shock) was not leaked for more than 30 minutes at a water pressure of 4 m, Is at least 20 cc / min (@ 1 PSI).

However, in the case of Comparative Example 1, the acoustic transmission loss was 10 dB or more, and the waterproofing waterproof property (room temperature, low temperature, high temperature / high humidity, thermal shock) leaked even at a water pressure of 1.5 m.

In other words, in Examples 1 to 3, polyvinylidene fluoride was electrospun and oriented uniaxially during manufacture to control the microstructure of the nanomembrane, in particular, the orientation of the nanofibers, so that not only excellent sound permeability was obtained but also water- It can be seen that this excellent waterproof ventilation sheet is produced.

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.

1: solution tank
2: metering pump
3: Nozzle
4:
6: High voltage generator
100: Waterproof ventilation sheet
10: nanomembrane
20: Adhesive layer
20a: peripheral portion 20b: central portion
200: jig
210:

Claims (11)

Wherein the nanofibers comprise a nanomembrane integrated into a nonwoven fabric comprising a plurality of pores,
The nanomembrane has an anisotropy (MD elastic modulus / TD elastic modulus) in the machine direction (MD) and a transverse direction (TD) of 1.5 to 10.0,
Waterproof breathable sheet with waterproof waterproofing that does not leak at normal temperature (20 ℃ ± 5 ℃), water pressure over 1.5 m for 30 minutes, and acoustic transmission loss less than 10 dB at 1000 Hz. The method according to claim 1,
The nanomembrane has a shape with an aspect ratio (SD: LD) of 2 to 50 of the smallest diameter (SD) of the pore with respect to the longest diameter (LD) of the pore,
And the longest diameter (LD) of the pores is oriented in a direction parallel to the longitudinal direction of the nanomembrane. The method according to claim 1,
Wherein the nanomembrane has an absorption coefficient of the nanomembrane of less than 0.2 at 1000 Hz and an acoustic transmission loss of less than 10 dB at 1000 Hz due to the anisotropy of the longitudinal and transverse moduli. The method according to claim 1,
Wherein the nanofiber has a diameter of 50 nm to 3000 nm, a thickness of 3 占 퐉 to 40 占 퐉, a pore size of 0.1 占 퐉 to 5 占 퐉, a porosity of 40% to 90%, an air permeability of 0.1 CFM To 20 CFM, a water pressure of 3000 mmH ₂ O or more, a water repellency grade of 4 or more, an elastic modulus of 1 MPa to 1000 MPa, and a basis weight of 0.5 g / m 2 to 20 g / m 2. The method according to claim 1,
The waterproof ventilation sheet was subjected to high temperature / high humidity conditions (50 DEG C, 95% humidity, 72 hours, no water leaks for at least 30 minutes at a water pressure of 1.5 m or more in the case of waterproof waterproof property at low temperature (Measured after repeating 30 cycles of one cycle maintaining -40 ° C and 85 ° C for 1 hour respectively) without leaking at a water pressure of 1.5 m or more for 30 minutes or more and 1.5 m or more Wherein the waterproof sheet does not leak from the water pressure for more than 30 minutes. The method according to claim 1,
Wherein the waterproof breathable sheet has a breathability of 20 cc / min (@ 1 PSI) or more. The method according to claim 1,
Wherein the nanofiber is made of polyvinylidene difluoride (PVdF). The method according to claim 1,
Wherein the waterproof breathable sheet further comprises an adhesive layer on one side or both sides of the nanomembrane. 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 uniaxially orienting the nanomembrane,
The nanomembrane has an anisotropy (MD elastic modulus / TD elastic modulus) in the machine direction (MD) and a transverse direction (TD) of 1.5 to 10.0,
(20 ° C ± 5 ° C), hydraulic waterproofing that does not leak over a water pressure of 1.5 m or more for 30 minutes or more, and acoustic transmission loss of less than 10 dB at 1000 Hz. 10. The method of claim 9,
Wherein the uniaxial orientation of the nanomembrane is performed by applying a tensile force of 1.5 to 20 times in the longitudinal direction to the width direction of the nanomembrane. 10. The method of claim 9,
In the uniaxial orientation of the nanomembrane, the winding speed of the nanomembrane is adjusted to 0.01 m / min to 20 m / min, and the TR (traverse) speed is adjusted to 0.001 m / min to 10 m / min. A method for manufacturing a waterproof breathable sheet.

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