KR20240106979A - A nanomembrane, waterproof ventilation sheet including the same, method for manufacturing the nanomembrane - Google Patents

Abstract

The present invention is formed of synthetic fibers, contains less than 15% by weight of carbon black relative to the total weight of the synthetic fibers, the aspect ratio of the carbon black particles is 1.0 to 5, and has a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O. It relates to a nanomembrane having an air permeability of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec, a waterproof ventilation sheet including the same, and a method of manufacturing the nanomembrane.

Description

Nanomembrane, waterproof ventilation sheet including the same, and method for manufacturing the nanomembrane {A nanomembrane, waterproof ventilation sheet including the same, method for manufacturing the nanomembrane}

The present invention relates to a nanomembrane, a waterproof breathable sheet including the same, and a method of manufacturing the nanomembrane.

In various electronic devices such as mobile devices, electronic devices such as hearing aids, communication equipment such as walkie-talkies, and automobile headlamps, ventilation is provided to the electronic device to maintain pressure balance inside and outside the electronic device, and at the same time, the electronic device Waterproofing, which prevents water/liquid from penetrating inside, and dustproof, which prevents contamination/dust from penetrating, are both required. Accordingly, the electronic devices include a waterproof and breathable sheet that is both waterproof/dustproof and breathable.

In particular, electronic devices such as the above-mentioned mobile devices have been added with various performances and functions, and as a result, the frequency of use is increasing, so not only are they waterproof and dustproof in various environments, but also acoustic performance that transmits sound in a form close to the original sound without distortion. is also being requested.

Recently, as the demand for use of mobile devices in underwater environments in winter and summer increases, there is a demand for high-specification waterproof performance in various environments.

Accordingly, there is still a need for a waterproof breathable sheet to maintain excellent waterproofness even when exposed to various environments.

The present invention is intended to provide a nanomembrane with improved waterproofness and breathability under room temperature, low temperature, thermal shock, high temperature and high humidity conditions, a waterproof breathable sheet containing the same, and a method of manufacturing the same.

According to one aspect, it is formed of synthetic fibers, includes less than 15% by weight of carbon black relative to the total weight of the synthetic fibers, and the aspect ratio of the carbon black particles is 1.0 to 5, and 5,000 mmH ₂ O to 15,000 mmH ₂ O A nanomembrane is provided, which has a water pressure resistance of , and an air permeability of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec.

According to one embodiment, the synthetic fiber is polyvinylidene fluoride, polytetrafluoroethylene, polyethylene glycol, polyethyleneimine, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylate, polyacrylamide, It may include polyvinyl alcohol, or a combination thereof.

According to one embodiment, the synthetic fiber may include polyvinylidene fluoride.

According to one embodiment, the carbon black particles may be included in the synthetic fiber in a dispersed form.

According to one embodiment, the aspect ratio of the carbon black particles may be 1.3 to 4.

According to one embodiment, the diameter of the carbon black particles may be 10 nm to 2000 nm.

According to one embodiment, the nanomembrane may be the synthetic fibers integrated in the form of a non-woven fabric by electrospinning.

According to one embodiment, the nanomembrane may have an elastic modulus of 50 MPa to 1,000 MPa, as measured according to the ASTM D 882 measurement method.

According to one embodiment, the nanomembrane may have a porosity of 50% to 90% and an air permeability measured according to the ASTM D 737 measurement method of 1ccs to 10ccs.

According to one embodiment, the nanomembrane may have a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O as measured according to the KS K ISO 811 measurement method.

According to one aspect, it includes the above-described nanomembrane, has hydraulic waterproofing property that does not leak for more than 30 minutes under water pressure of 5 m or more at room temperature (20°C ± 5°C), and has a sound transmission loss of less than 5 dB at 1000 Hz, A waterproof, breathable sheet is provided, having a breathability of at least 30 cc/min at 1 PSI pressure.

According to one embodiment, the waterproof breathable sheet does not leak for more than 30 minutes at a water pressure of 5 m or more under the low temperature conditions below, does not leak for more than 30 minutes at a water pressure of 5 m or more under the high temperature conditions below, and does not leak for more than 30 minutes at a water pressure of 5 m or more under the following thermal shock conditions. Water leakage may not occur for more than 30 minutes under water pressure.

[Low temperature conditions]

The waterproof ventilated sheet was exposed to a temperature of -20°C for 72 hours prior to water leakage measurement.

[High temperature conditions]

Before measuring water leakage, the waterproof ventilation sheet was exposed to a temperature of 50°C and 95% humidity for 72 hours.

[Thermal shock conditions]

Before measuring water leakage, the cycle of exposure to -40℃ and 85℃ temperature for 1 hour each was repeated 30 times.

According to one embodiment, the waterproof ventilation sheet may further include an adhesive layer on one or both sides of the nanomembrane.

According to one aspect, preparing a mixed spinning solution obtained by mixing a synthetic fiber spinning solution and carbon black particles; And electrospinning the mixed spinning solution to obtain a nanomembrane in which synthetic fibers containing carbon black particles are integrated in the form of a non-woven fabric containing a plurality of pores,

The carbon black particles are contained in less than 15% by weight relative to the total weight of the nanomembrane, and the aspect ratio of the carbon black particles is 1.0 to 5,

The aspect ratio of the carbon black particles is 1.0 to 5, has a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O, and has an air permeability of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec. , a method for manufacturing a nanomembrane is provided.

According to one embodiment, the synthetic fiber spinning solution is prepared by dissolving synthetic fiber raw materials in a solvent, and the synthetic fiber raw materials may be included in an amount of more than 5% by weight and less than 25% by weight based on solid content.

According to one embodiment, the mixed spinning solution may have a viscosity of 100 cp to 3000 cp and an electrical conductivity of 10 μS/cm to 40 μS/cm.

According to one aspect, a method of manufacturing a waterproof breathable sheet is provided, further comprising providing an adhesive layer on one or both sides of the nanomembrane obtained according to the above-described nanomembrane manufacturing method.

According to one embodiment, the waterproof breathable sheet has hydraulic waterproofing properties that do not leak for more than 30 minutes under water pressure of 5 m or more at room temperature (20°C ± 5°C), and sound transmission loss may be less than 5 dB at 1000 Hz.

According to another aspect, an electronic device including the waterproof, breathable sheet disclosed herein may be provided. Examples of the electronic devices include mobile phones, portable pads, speakers, and sound devices such as microphones.

The nanomembrane according to one aspect is manufactured by electrospinning carbon black particles with an aspect ratio of 1.0 to 5 together with a synthetic fiber spinning solution, so that it can be used under low temperature, high temperature, thermal shock, high temperature and high humidity conditions without sound loss or deterioration of air permeability. Water resistance has been significantly improved.

Figure 1 is a diagram schematically showing the structure of a waterproof breathable sheet according to an embodiment of the present invention.
Figure 2 is a diagram schematically showing the structure of a waterproof ventilation sheet according to another embodiment of the present invention.
Figure 3 is a diagram schematically showing the structure of a waterproof ventilation sheet according to another embodiment of the present invention.
Figure 4 is a diagram schematically showing the structure of a waterproof ventilation sheet according to another embodiment of the present invention.
Figure 5 is a photograph of the appearance of the nanomembrane prepared in Example 1.
Figure 6 is a photograph of the appearance of the nanomembrane prepared in Comparative Example 1.
Figure 7 is a photograph confirming the agglomeration phenomenon of the carbon black used in Example 1.
Figure 8 is a photograph confirming the agglomeration phenomenon of the carbon black used in Comparative Example 1.

Hereinafter, the term “above” or “above” may include not only what is directly above in contact but also what is above without contact. Singular expressions include plural expressions unless the context clearly dictates otherwise. Additionally, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

The use of the term “said” and similar referential terms may refer to both the singular and the plural. Unless the order of the steps constituting the method is clearly stated or stated to the contrary, these steps may be performed in any appropriate order and are not necessarily limited to the order described.

As used herein, the terms “comprise”, “comprising”, “formed”, “has”, “having” or any of these terms. Any other variations are intended to cover non-exclusive inclusions. For example, a process, method, article, or apparatus that includes a list of elements is not necessarily limited to only those elements and may include other elements not explicitly listed or inherent to such process, method, article, or apparatus. It may be possible. Additionally, unless explicitly stated to the contrary, “or” refers to an inclusive “or” and does not refer to an exclusive “or.”

The use of all examples or illustrative terms is simply for explaining the technical idea in detail, and the scope is not limited by these examples or illustrative terms unless limited by the claims.

Figure 1 shows a schematic diagram of a waterproof breathable sheet according to one embodiment of the present invention.

Referring to Figure 1, the waterproof ventilation sheet 10 includes a nanomembrane 100 and an adhesive portion 110. At this time, the adhesive portion 110 is provided on one side of the nanomembrane 100.

The adhesive portion 110 may be provided along a portion of one side of the nanomembrane 100, for example, along the edge of the nanomembrane 100, and may be provided on one side of the nanomembrane 100 on which the adhesive portion 110 is provided. The area where the adhesive portion 110 is not provided forms a ventilation area B1 through which air can pass.

The adhesive portion 110 may be composed of a single layer or a multilayer of three or more layers in which an adhesive is laminated on both sides of a substrate.

According to one embodiment, the adhesive portion 110 may include a substrate 111 and a first adhesive layer 112 and a second adhesive layer 113 provided on both sides of the substrate.

The first adhesive layer 112 is interposed between the substrate 111 and the nanomembrane 100 to ensure a firm bond between the substrate 111 and the nanomembrane 100.

The first adhesive layer 112 can be used without limitation any known adhesive that can ensure a firm bond between the nanomembrane 100 and the substrate 111, for example, epoxy adhesive, urethane adhesive, and acrylic adhesive. , thermosetting adhesives, and petroleum resin adhesives can be used.

The second adhesive layer 113 can ensure a firm bond between the substrate 111 and the components of the electronic device to which the waterproof ventilation sheet 10 will be applied.

The second adhesive layer 113 can be used without limitation any known adhesive that can ensure a firm bond between the substrate 111 and components of an electronic device, for example, epoxy adhesive, urethane adhesive, acrylic adhesive, Thermosetting adhesives and petroleum resin adhesives can be used.

According to one embodiment, the first adhesive layer 112 and the second adhesive layer 113 may include the same or different adhesives. For example, the first adhesive layer 112 and the second adhesive layer 113 may use the same adhesive, for example, an acrylic adhesive.

The substrate 111 may be in the form of a film, a sheet, or a foam, and may be used without limitation as long as it can function as a carrier for the adhesive layers 112 and 113. For example, the substrate 111 may include a polyester-based substrate, a polyurethane-based substrate, a polyethylene-based substrate, a polyolefin-based substrate, or a combination thereof. For example, the substrate may be polyurethane foam or polyolefin foam.

The substrate 111 may be a single-layer film or a single-layer sheet, but is not limited thereto, and may be a multi-layer laminate in which a plurality of films or sheets are stacked.

By providing the above-described adhesive portion 110 on one surface of the nanomembrane 100, the waterproof breathable sheet 10 and the electronic device are firmly coupled, and waterproofness can be improved without deteriorating the sound permeability of the electronic device.

The nanomembrane 100 will be described later.

Figure 2 is a schematic diagram of a waterproof breathable sheet 20 according to another embodiment.

The waterproof breathable sheet 20 may have a structure in which two waterproof breathable sheets are stacked.

Figure 2 illustrates a structure in which two waterproof, breathable sheets are stacked, but two or more waterproof, breathable sheets may be stacked as needed.

It includes the nanomembrane 200 and a first adhesive portion 210 provided on one side of the nanomembrane.

In FIG. 2, the nanomembrane 100 and the first adhesive portion 110 refer to the description in FIG. 1, and the information regarding the nanomembrane 200 and the first adhesive portion 210 also refer to the corresponding nanomembrane in the description of FIG. Refer to the contents of (100) and the first adhesive portion (110).

Figure 3 is a schematic diagram of a waterproof breathable sheet 30 according to another embodiment.

The waterproof ventilation sheet 30 includes a nanomembrane 300, a first adhesive portion 310 and a second adhesive portion 320 provided on both sides of the nanomembrane 300, and a shock absorbing layer provided on the second adhesive portion. do.

Here, for information regarding the first adhesive portion 310, refer to the corresponding content of the first adhesive portion 110 in the description of FIG. 1.

The second adhesive portion 320 may be provided on a portion of the surface of the nanomembrane 300 on which the first adhesive portion 310 is not provided, for example, along the edge of the nanomembrane 300, and may be provided along the edge of the nanomembrane 300. Among the surfaces of the nanomembrane 300 provided with the adhesive portion 320, the area where the second adhesive portion 320 is not provided forms a ventilation area B2 through which air can pass.

The second adhesive portion 320 may be composed of a single layer or a multilayer of three or more layers in which adhesive is laminated on both sides of a substrate.

According to one embodiment, the second adhesive portion 320 may include a substrate 321 and a third adhesive layer 322 and a fourth adhesive layer 323 provided on both sides of the substrate.

The third adhesive layer 322 is interposed between the substrate 321 and the nanomembrane 300 to ensure a firm bond between the substrate 321 and the nanomembrane 300.

The third adhesive layer 322 can be used without limitation any known adhesive that can ensure a firm bond between the nanomembrane 300 and the substrate 321, for example, epoxy adhesive, urethane adhesive, and acrylic adhesive. , thermosetting adhesives, and petroleum resin adhesives can be used.

The fourth adhesive layer 323 can ensure a firm bond between the substrate 321 and the shock absorption layer 330.

The fourth adhesive layer 323 can be used without limitation any known adhesive that can ensure a firm bonding of the shock absorbing layer 330, for example, epoxy adhesive, urethane adhesive, acrylic adhesive, thermosetting adhesive, and petroleum resin. Adhesives may be used.

According to one embodiment, the third adhesive layer 322 and the fourth adhesive layer 323 may include the same or different adhesives. For example, the third adhesive layer 322 and the fourth adhesive layer 323 may use the same adhesive, for example, an acrylic adhesive.

The substrate 321 may be in the form of a film, a sheet, or a foam, and may be used without limitation as long as it can function as a carrier for the adhesive layers 322 and 323. For example, the substrate 321 may include a polyester-based substrate, a polyurethane-based substrate, a polyethylene-based substrate, a polyolefin-based substrate, or a combination thereof. For example, the substrate 321 may be a polyester film.

The substrate 321 may be a single-layer film or a single-layer sheet, but is not limited thereto and may be a multi-layer laminate in which a plurality of films or sheets are stacked.

The shock absorption layer 330 is a functional layer that absorbs external shocks and blocks energy transfer to the lower layer. For example, air-filled foam materials, elastic rubber, and synthetic petroleum resin materials may be used. .

Examples of foam materials include polyurethane foam, polyolefin foam, and phenolic foam. Synthetic petroleum resin materials include polypropylene and polyvinyl chloride, and rubber includes natural rubber, latex, and nitrile butadiene rubber.

According to one embodiment, the shock absorption layer 330 may include polyurethane foam.

The shock absorption layer 330 may be composed of a single layer or multiple layers. When the shock-absorbing layer 330 is composed of a plurality of layers, each layer may include one or more of the aforementioned foam materials, rubber, and synthetic petroleum resin materials.

Figure 4 is a schematic diagram of a waterproof breathable sheet 40 according to another embodiment.

The waterproof ventilation sheet 40 may have a structure in which two waterproof ventilation sheets are stacked.

The waterproof breathable sheet 40 illustrated in FIG. 4 illustrates a structure in which the two waterproof breathable sheets described in FIG. 3 are stacked, but two or more waterproof breathable sheets may be stacked as needed.

It includes the nanomembrane 400 and a first adhesive portion 410 and a second adhesive portion 420 provided on both sides of the nanomembrane, and further includes a shock absorption layer 430 on the second adhesive portion 420.

In FIG. 4, the nanomembrane 300, the first adhesive portion 310, the second adhesive portion 320, and the shock absorption layer 330 refer to the description in FIG. 3, and the nanomembrane 400 and the first adhesive portion 410, The contents of the second adhesive portion 420 and the shock absorbing layer 430 are also described in the description of FIG. 3 as the corresponding nanomembrane 300, first adhesive portion 310, second adhesive portion 320, and shock absorbing layer 330. Please refer to the contents.

In addition, the structure of a modified waterproof breathable sheet, such as a waterproof breathable sheet having a structure in which the waterproof breathable sheet 30 described in FIG. 3 is laminated on the waterproof breathable sheet 10 described in FIG. 1, is not specifically described, but this Equivalents of the invention are included in the present invention.

Hereinafter, the nanomembranes 100, 200, 300, and 400 illustrated in FIGS. 1 to 4 will be described in detail.

The nanomembrane according to one embodiment can be manufactured by electrospinning a mixed spinning solution obtained by mixing a synthetic fiber spinning solution and carbon black particles.

The synthetic fiber spinning solution according to one embodiment may be a solution in which the main materials constituting the synthetic fiber are dissolved in a solvent.

For example, the raw materials constituting the synthetic fiber are polymers such as polyvinylidene fluoride, polytetrafluoroethylene, polyethylene glycol, polyethyleneimine, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, and polyacrylate. , polyacrylamide, polyvinyl alcohol, or a combination thereof.

For example, the raw material constituting the synthetic fiber may include polyvinylidene fluoride in consideration of the waterproofing properties of the nanomembrane.

According to one embodiment, solvents for dissolving the synthetic fiber raw materials include dimethylacetamide, dimethylacetone, dimethyl sulfoxide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, trimethylphosphate, and tetramethylurea. , dimethylformamide, methyl ethyl ketone, tetrahydrofuran, or a combination thereof.

The synthetic fiber spinning solution may contain more than 5% by weight and less than 25% by weight of the synthetic fiber raw material based on solid content. For example, the synthetic fiber raw material may be included in an amount of 10 to 20% by weight based on solid content. If it is less than 5% by weight based on solid content, spinning is difficult, and if it is more than 25% by weight, water pressure resistance, etc. may decrease and waterproofness may deteriorate.

According to one embodiment, the carbon black particles may satisfy an aspect ratio of 1.0 to 5, for example, 1.2 to 5 or 1.3 to 4. When the carbon black particles satisfy this aspect ratio, the agglomeration phenomenon between carbon blacks can be suppressed as much as possible, and excellent kneading properties with the synthetic fiber spinning solution can be obtained.

According to one embodiment, the diameter of the carbon black particles may be 10 nm to 2000 nm. For example, the carbon black particles may have a diameter of 10 nm to 1500 nm. When the diameter of the carbon black particles satisfies the above range, dispersibility in the synthetic fiber spinning solution is good, and agglomeration of the carbon black particles can be minimized.

The carbon black particles may be included in less than 15% by weight based on the total weight of the nanomembrane. For example, the carbon black particles may range from 0.1 wt% to less than 15 wt%, from 0.6 wt% to 14 wt%, from 0.7 wt% to 13 wt%, from 0.8 wt% to 12 wt%, from 0.9 wt% to 11 wt%, Alternatively, it may be included from 1% to 10% by weight.

The mixed spinning solution may have a viscosity of 100 cp to 3000 cp. For example, the viscosity of the mixed spinning solution may be 150 cp to 2500 cp, 170 cp to 2000 cp, or 190 cp to 1800 cp, but is not necessarily limited thereto.

If the viscosity of the mixed spinning solution satisfies the above range, it is easy to manufacture synthetic fibers by electrospinning. If the viscosity is excessively high, not only is it difficult to control the discharge speed of the spinning solution, but processability is also reduced due to nozzle clogging. As expected, if the viscosity is excessively low, the formation of fibers may be difficult.

The electrical conductivity of the mixed spinning solution may be 10 μS/cm to 40 μS/cm. The mixed spinning solution includes a predetermined amount of carbon black particles of the specific type described above, so that the electrical conductivity of the mixed spinning solution can be adjusted to the above range. The nanomembrane according to one embodiment of the present invention is manufactured by electrospinning, and the control of the electrical conductivity of the spinning solution is influenced by the voltage applied during the electrospinning process, thereby changing the diameter of the final fiber and the membrane obtained from the fiber. Affects pore distribution and shape. By controlling the microstructure of the nanomembrane through controlling the electrospinning conditions, it is possible to manufacture a breathable sheet with excellent elastic modulus, hydraulic waterproofness, and breathability.

According to one embodiment, the synthetic fiber obtained by electrospinning the mixed spinning solution may have a diameter of 50 nm to 3000 nm. For example, the synthetic fiber may have a diameter of 60 nm to 2500 nm, 70 nm to 2200 nm, or 80 nm to 2000 nm.

By electrospinning the mixed spinning solution, synthetic fibers containing carbon black particles can be integrated into a non-woven fabric containing multiple pores to form a nanomembrane.

The non-woven nanomembrane includes multiple pores, has a porosity of 50% to 90%, and may have a basis weight of 0.5 g/m ² to 15 g/m ² .

According to one embodiment, the synthetic fibers obtained through electrospinning may include carbon black particles.

For example, at least some of the synthetic fibers may include carbon black particles on their surface or within the fibers.

The nanomembrane obtained by the above-described method contains a specific content of carbon black with a specific aspect ratio, and is manufactured by electrospinning and integrating it into a non-woven fabric, so that it can have the following physical properties.

The nanomembrane according to one embodiment of the present invention may have an elastic modulus of 50 MPa to 1,000 MPa, as measured according to the ASTM D 882 measurement method. For example, the elastic modulus of the nanomembrane may be 60 MPa to 900 MPa, 70 MPa to 800 MPa, 80 MPa to 700 MPa, 90 MPa to 600 MPa, or 100 MPa to 500 MPa.

The nanomembrane according to one embodiment of the present invention may have an air permeability measured according to the ASTM D 737 measurement method of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec. For example, the air permeability of the nanomembrane may be 1.5 ccs to 9 ccs, 1.6 ccs to 8 ccs, 1.7 ccs to 7 ccs, 1.8 ccs to 6 ccs, 1.9 ccs to 5 ccs, or 2 ccs to 4 ccs. .

The nanomembrane according to one embodiment of the present invention may have a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O as measured according to the KS K ISO 811 measurement method. For example, the water pressure of the nanomembrane may be 6,000 mmH ₂ O to 13,000 mmH ₂ O.

The waterproof ventilation sheet according to one embodiment may further include the step of providing an adhesive portion on one or both sides of the nanomembrane after manufacturing the nanomembrane as described above.

The adhesive part can be provided by applying it directly on the nanomembrane, or it can be provided by manufacturing the adhesive part separately and then attaching it to the nanomembrane.

For materials and specific configurations of the adhesive portion, refer to the contents of the adhesive portion described in FIGS. 1 to 4.

The waterproof breathable sheet according to one embodiment may further include providing an adhesive portion on one or both sides of the nanomembrane as described above and then providing a shock absorbing layer on at least one side of the adhesive portions.

For the material and specific configuration of the shock absorbing layer, refer to the information regarding the shock absorbing layer described in FIGS. 1 to 4.

A waterproof, breathable sheet manufactured according to one embodiment may have the following physical properties.

The waterproof breathable sheet may have a breathability of 30 cc/min or more at a pressure of 1 PSI. For example, the breathability of the waterproof breathable sheet is 30 cc/min to 100 cc/min, 40 cc/min to 90 cc/min, 50 cc/min to 80 cc/min, or 50 cc/min to 70 cc/ It can be min.

The waterproof breathable sheet manufactured according to one embodiment does not leak for more than 30 minutes at a water pressure of 5 m or more under the low temperature conditions below, does not leak for more than 30 minutes at a water pressure of 5 m or more under the high temperature conditions below, and does not leak for more than 30 minutes at a water pressure of 5 m or more under the following thermal shock conditions. Water leakage may not occur for more than 30 minutes at water pressure above this level.

[Low temperature conditions]

The waterproof ventilated sheet was exposed to a temperature of -20°C for 72 hours prior to water leakage measurement.

[High temperature conditions]

Before measuring water leakage, the waterproof ventilation sheet was exposed to a temperature of 50°C and 95% humidity for 72 hours.

[Thermal shock conditions]

Before measuring water leakage, the cycle of exposure to -40℃ and 85℃ temperature for 1 hour each was repeated 30 times.

For example, the waterproof breathable sheet does not leak for more than 30 minutes at a water pressure of 5 m or more under the low temperature condition, does not leak for more than 30 minutes at a water pressure of 5 m or more under the high temperature condition, and does not leak for more than 30 minutes at a water pressure of 5 m or more under the thermal shock condition. There may be no more water leaks.

For example, the waterproof breathable sheet does not leak for more than 70 minutes at a water pressure of 5 m or more under the low temperature condition, does not leak for more than 50 minutes at a water pressure of 5 m or more under the high temperature condition, and does not leak for more than 60 minutes at a water pressure of 5 m or more under the thermal shock condition. It may not leak.

The waterproof breathable sheet according to one embodiment of the present invention can be used in electronic devices that require both waterproofing and breathability, such as sound devices such as mobile phones, portable pads, speakers, and microphones.

Hereinafter, the present invention will be described in more detail through specific examples, but the present invention is not limited to the following examples.

The evaluation methods used in the following examples and comparative examples are as follows.

Assessment Methods

(1) Unit weight: ASTM D 3776

(2) Electrical conductivity: KS C IEC 60746-3

(3) Air permeability: Measured under the conditions of an area of 38㎠ and a static pressure of 125Pa using the ASTM D 737 method.

(4) Water pressure: Apply KS K ISO 811 low water pressure method to measure the pressure at the point where the first water droplet is formed by pressurizing an area of 100 ㎠ at 2,000 ㎜H2O/min.

(5) Thickness: Measure thickness by applying KS K 0506 or ISO 4593 and ISO 9073-2

(6) Sound transmission loss: evaluated by sound transmission loss test, ASTM E-2611-09

(7) Water pressure resistance: Use of a water pressure measuring device that can apply a certain water pressure at a depth of 0 m to 20 m for a certain time as used in KS K ISO 811. In the case of low temperature evaluation, evaluation was conducted after pretreatment at -20 ℃ for 72 hours, high temperature/high humidity conditions were evaluation after pretreatment at 50 ℃ and 95% humidity for 72 hours, and thermal shock conditions were evaluation at -40 ℃ and 85 ℃ for 1 hour each. After repeating 30 cycles of maintenance, evaluation was performed under room temperature (20 ℃ ± 5 ℃) conditions.

(8) Breathability: Measure the flow rate of air passing through a circular area with a diameter of 1 mm for 1 minute under 1 PSI pressure using the gas permeation method of the capillary flow pore measuring device.

(9) Porosity: Porosity (%) = [1 - (A/B)] x 100 = {1 - [(C/D) / B]} x 100,

(A = density of nanomembrane, B = density of nanomembrane polymer, C = weight of nanomembrane, D = volume of nanomembrane)

(10) Elasticity modulus: Apply ASTM D 882, measure MD (machine direction) and TD (Transverse direction) 10 times each and use the average value excluding the maximum and minimum values.

(11) Aspect ratio: The aspect ratio is defined by the following formula, where "a" refers to the length of the longest part of the length of both ends of the particle, and "b" and "b'" refer to the length of both ends of the total length. It means the longest and shortest width parts of the length excluding 10% of the length. That is, (b+b')/2 represents the average length of the width.

Aspect ratio (F) = a/{(b+b')/2}

Example and Comparative example

As a synthetic fiber raw material, polyvinylidene fluoride (PVdf) was dissolved in a dimethylacetamide/acetone mixed solvent at the concentration shown in Table 1 below, and then carbon black was added in the amount shown in Table 1 below relative to the weight of polyvinylidene fluoride for mixing. The solution used was prepared.

The mixed electrospinning solution was electrospun using an electrospinning device at a voltage of 50 to 60 kV and a discharge rate of 1 cc/min to prepare a nanomembrane.

The nanomembrane, the double-sided tape, and the impact protection material were sequentially added, so that the bottom side of the double-sided tape was adhered to the top surface of the nanomembrane, and the impact protection material was laminated thereon. Next, it passed through a mold moving at a certain pressure and speed and was cut to a certain size to manufacture a waterproof, breathable sheet.

division spinning solution carbon black Radiation conditions Raw material Solid content (%) viscosity
(cP) electrical conductivity
(μS/cm) aspect ratio
(F) particle size
(nm) density
(%) Voltage
(kV) Discharge amount
(cc/min) Example 1 PVDF 10 204 12 3.5 800±50 One 50 7 Example 2 PVDF 15 621 34.1 1.4 100±50 10 60 0.5 Example 3 PVDF 20 1513 23.5 3.5 800±50 5 50 5 Example 4 PVDF 10 216 21.5 1.4 100±50 5 50 3.5 Example 5 PVDF 20 1523 32.5 1.4 100±50 10 60 One Example 6 PVDF 15 603 12.4 3.5 800±50 One 60 2 Example 7 PVDF 15 614 22.7 2.6 300±50 5 55 1.7 Example 8 PVDF 10 223 22.3 2.6 300±50 5 55 1.7 Example 9 PVDF 20 1560 23.1 2.6 300±50 5 55 1.7 Example 10 PVDF 15 593 13.6 2.6 300±50 One 55 1.7 Example 11 PVDF 15 614 31.2 2.6 300±50 10 55 1.7 Comparative Example 1 PVDF 10 192 4 - - - 50 1.5 Comparative Example 2 PVDF 20 1503 5.3 - - - 60 0.35 Comparative Example 3 PVDF 20 1545 22.2 8.2 100±50 5 60 0.5 Comparative Example 4 PVDF 25 2213 25.8 2.6 300±50 5 55 1.7 Comparative Example 5 PVDF 15 593 4.7 - - - 55 1.7

Evaluation example 1: nano of the membrane Appearance evaluation

Photographs were taken of the nanomembrane prepared in Example 1 and the nanomembrane prepared in Comparative Example 1, and are shown in Figures 5 and 6, respectively.

Referring to Figure 5, the nanomembrane of Example 1 electrospun by mixing carbon black had a black or gray color, and referring to Figure 6, the nanomembrane of Comparative Example 1 that did not contain carbon black had a white color. It was confirmed that it was noticeable.

Evaluation example 2: Evaluation of carbon black

10 wt% of carbon black with an aspect ratio of 3.5 used in Example 1 was dispersed in a dimethylacetamide or dimethylformamide solvent and stored at room temperature for about a month. As a result, no agglomeration was confirmed as shown in FIG. 7. 10 wt% of the carbon black with an aspect ratio of 8.2 used in Comparative Example 3 was dispersed in a dimethylacetamide or dimethylformamide solvent and stored at room temperature for about a month. As a result, it gelled and agglomerated as shown in Figure 8. It was confirmed that this occurred.

By selectively using carbon black with a specific aspect ratio, the electrical conductivity of the mixed spinning solution is improved without bias to one side, and the shape and structure of the pores of the nanomembrane are adjusted by electrospinning, without sound transmission loss. Waterproofing at room temperature, low temperature, thermal shock, high temperature and high humidity is improved, and breathability is also improved.

Evaluation example 3: Nano membrane and evaluation of waterproof and breathable sheets including the same.

The unit weight, fiber diameter, thickness, porosity, air permeability, elastic modulus, and water pressure resistance of the nanomembranes used in Examples 1 to 11 and Comparative Examples 1 to 5 were measured, and the room temperature, low temperature, and thermal shock of the waterproof breathable sheet manufactured therefrom were measured. , hydraulic waterproof performance, breathability, and sound transmission loss at high temperature and high humidity were measured and summarized in Tables 2 and 3 below.

division specification ( nanomembrane ) unit weight
(g/㎡) fiber diameter
(㎚) thickness
(㎛) Porosity
(%) air permeability
(㎤/㎠/sec) modulus of elasticity
(MPa) water pressure
(㎜H₂O) Example 1 5.2 910 15 73.5 3.4 180 6,100 Example 2 5.4 530 16 75.6 2.2 320 11,800 Example 3 5.7 640 16 74.3 2.8 250 8,200 Example 4 5.2 670 15 75.1 3 230 7,900 Example 5 5.1 590 15 74.2 2.3 310 10,900 Example 6 6.2 1010 16 73.8 3.2 150 6,400 Example 7 5.9 650 15 75.0 2.9 270 9,100 Example 8 5.4 680 16 74.5 2.5 210 8,300 Example 9 5.7 910 15 77.5 3.1 220 7,100 Example 10 5.9 980 16 74.5 2.9 180 6,800 Example 11 5.6 590 15 75.3 2.3 290 10,800 Comparative Example 1 5.2 1180 15 73.1 4.2 10 3,200 Comparative Example 2 5.9 1230 16 73.1 4.3 12 3,000 Comparative Example 3 5.5 1030 15 73.4 3.8 100 3,800 Comparative Example 4 5.3 1750 16 80.2 4.9 70 2,900 Comparative Example 5 5.6 1210 15 73.3 4.1 11 3,300

division Specifications (waterproof ventilated sheet) water pressure waterproofing
(room temperature) water pressure waterproofing
(low temperature) water pressure waterproofing
(thermal shock) water pressure waterproofing
(high temperature and humidity) breathable
(cc/min@1PSI) Sound transmission loss
(dB) Example 1 5m, 50 minutes 5m, 40 minutes 5m, 40 minutes 5m, 30 minutes 67 0.3 Example 2 5m, 100 minutes 5m, 90 minutes 5m, 90 minutes 5m, 80 minutes 52 0.5 Example 3 5m, 70 minutes 5m, 60 minutes 5m, 60 minutes 5m, 50 minutes 61 0.5 Example 4 5m, 70 minutes 5m, 60 minutes 5m, 60 minutes 5m, 50 minutes 63 0.4 Example 5 5m, 100 minutes 5m, 90 minutes 5m, 90 minutes 5m, 80 minutes 54 0.5 Example 6 5m, 50 minutes 5m, 40 minutes 5m, 40 minutes 5m, 30 minutes 66 0.4 Example 7 5m, 90 minutes 5m, 80 minutes 5m, 80 minutes 5m, 70 minutes 59 0.5 Example 8 5m, 70 minutes 5m, 60 minutes 5m, 60 minutes 5m, 50 minutes 57 0.5 Example 9 5m, 70 minutes 5m, 60 minutes 5m, 60 minutes 5m, 50 minutes 63 0.4 Example 10 5m, 50 minutes 5m, 40 minutes 5m, 40 minutes 5m, 30 minutes 63 0.4 Example 11 5m, 100 minutes 5m, 90 minutes 5m, 90 minutes 5m, 80 minutes 53 0.5 Comparative Example 1 5m, 2 minutes 5m, 0 minutes 5m, 0 minutes 5m, 0 minutes 74 0.2 Comparative Example 2 5m, 1 minute 5m, 0 minutes 5m, 0 minutes 5m, 0 minutes 76 0.2 Comparative Example 3 5m, 4 minutes 5m, 0 minutes 5m, 0 minutes 5m, 0 minutes 72 0.3 Comparative Example 4 5m, 1 minute 5m, 0 minutes 5m, 0 minutes 5m, 0 minutes 79 0.4 Comparative Example 5 5m, 1 minute 5m, 0 minutes 5m, 0 minutes 5m, 0 minutes 75 0.2

As shown in Table 2, the water pressure of the nanomembrane containing carbon black increases by about 2 to 4 times without significant changes in pores and thickness compared to the nanomembrane that does not contain carbon black, and the elastic modulus is up to about 32 times. It can be confirmed that there has been an increase. This means that when carbon black is included, the electrical conductivity that affects electrospinning changes, and the pore structure and shape of the nanomembrane are modified accordingly, improving the physical properties.

As shown in Table 3, the waterproof breathable sheets manufactured in Examples 1 to 11 were confirmed to have significantly improved waterproof performance compared to the waterproof breathable sheets of Comparative Example 3 using carbon black with an aspect ratio exceeding 5, and the carbon black It was confirmed that the waterproof performance was up to 50 to 100 times longer than that of the waterproof and breathable sheets of Comparative Examples 1, 2, and 5 that did not apply.

In addition, it can be seen that Comparative Example 4, where the solids content was 25% by weight, showed very low waterproofing performance compared to Example 7, which had a solid content of 15% by weight.

The above has been described with reference to embodiments, but these are merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the attached patent claims.

Claims (15)

It is formed of synthetic fibers and contains less than 15% by weight of carbon black relative to the total weight of the synthetic fibers,
The aspect ratio of the carbon black particles is 1.0 to 5,
It has a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O,
A nanomembrane having an air permeability of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec. According to paragraph 1,
The synthetic fiber is polyvinylidene fluoride, polytetrafluoroethylene, polyethylene glycol, polyethyleneimine, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylate, polyacrylamide, polyvinyl alcohol, or these. A nanomembrane containing a combination of. According to paragraph 2,
A nanomembrane wherein the synthetic fiber includes polyvinylidene fluoride. According to paragraph 1,
A nanomembrane wherein the carbon black particles are dispersed in the synthetic fiber. According to paragraph 1,
A nanomembrane wherein the aspect ratio of the carbon black particles is 1.3 to 4. According to paragraph 1,
A nanomembrane wherein the carbon black particles have a diameter of 10 nm to 2000 nm. According to paragraph 1,
The nanomembrane is a nanomembrane in which the synthetic fibers are integrated into a non-woven fabric by electrospinning. According to paragraph 1,
The nanomembrane has an elastic modulus of 50 MPa to 1,000 MPa, as measured according to the ASTM D 882 measurement method. According to paragraph 1,
The nanomembrane has a porosity of 50% to 90% and an air permeability of 1ccs to 10ccs measured according to the ASTM D 737 measurement method. According to paragraph 1,
The nanomembrane has a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O measured according to the KS K ISO 811 measurement method. Comprising a nanomembrane according to any one of claims 1 to 10,
It has water pressure resistance that does not leak for more than 30 minutes under water pressure of 5 m or more at room temperature (20℃±5℃), and the sound transmission loss is less than 5 dB at 1000 Hz.
Waterproof, breathable sheeting with a breathability of at least 30 cc/min at 1 PSI pressure. According to clause 11,
The waterproof ventilation sheet does not leak for more than 30 minutes at a water pressure of 5 m or more under the low temperature conditions below, does not leak for more than 30 minutes at a water pressure of 5 m or more under the following high temperature conditions, and leaks for more than 30 minutes at a water pressure of 5 m or more under the following thermal shock conditions. Non-waterproof, breathable sheets:
[Low temperature conditions]
The waterproof ventilated sheet was exposed to a temperature of -20°C for 72 hours prior to water leakage measurement.
[High temperature conditions]
Before measuring water leakage, the waterproof ventilation sheet was exposed to a temperature of 50°C and 95% humidity for 72 hours.
[Thermal shock conditions]
Prior to measuring water leaks, the cycle of exposure to -40℃ and 85℃ temperatures for 1 hour each was repeated 30 times. According to clause 11,
The waterproof breathable sheet further includes an adhesive layer on one or both sides of the nanomembrane. Preparing a mixed spinning solution obtained by mixing a synthetic fiber spinning solution and carbon black particles; and
A step of electrospinning the mixed spinning solution to obtain a nanomembrane in which synthetic fibers containing carbon black particles are integrated in the form of a non-woven fabric containing a plurality of pores,
The carbon black particles are contained in less than 15% by weight relative to the total weight of the nanomembrane,
The aspect ratio of the carbon black particles is 1.0 to 5,
It has a water pressure of 5,000 mmH ₂ O to 15,000 mmH ₂ O,
A method of manufacturing a nanomembrane having an air permeability of 1 cm ³ /cm ² /sec (ccs) to 10 cm ³ /cm ² /sec. According to clause 14,
The synthetic fiber spinning solution is prepared by dissolving synthetic fiber raw materials in a solvent, and the synthetic fiber raw materials are contained in an amount of more than 5% by weight and less than 25% by weight based on solid content,
The mixed spinning solution has a viscosity of 100 cp to 3000 cp and an electrical conductivity of 10 μS/cm to 40 μS/cm.