Ventilation membrane, ventilation member, and light-emitting device

Abstract

The provided breathable film has breathability in the thickness direction, is colored, and has a first main surface and a second main surface located on the opposite side of the first main surface. The second main surface exhibits a higher brightness than the first main surface. The absolute value of the difference in brightness between the first main surface and the second main surface is 1.5 or more and 76 or less. The brightness of the second main surface is 20 or more and 95 or less. The luminous transmittance of light transmitted from the first main surface to the second main surface is 0.015 or less. However, the brightness is determined based on the CIE 1976 L standard defined in JIS Z8781-4:2013. * ,a * ,b * Color space lightness L * The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016. This breathable film is suitable for use in light-emitting devices such as lamps.

Description

[Technical Field]

[0001] The present invention relates to a ventilation film, and a ventilation member and a light-emitting device that include the same. [Background technology]

[0002] An opening is usually provided in the housing of a vehicle electrical component such as a lamp. The provision of the opening ensures ventilation between the inside and outside of the housing, thereby, for example, alleviating pressure changes that may occur inside the housing. Patent Document 1 discloses a technique for fixing a ventilation membrane to the opening of the housing. Patent Document 1 also describes that fixing the ventilation membrane can ensure ventilation while preventing water and dust from entering the inside of the housing, and describes fluororesin porous bodies and polyolefin porous bodies as examples of ventilation membranes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-318557 Summary of the Invention [Problem to be solved by the invention]

[0004] Fluororesin porous bodies and polyolefin porous bodies are usually white or near-white in color. Meanwhile, vehicle lamps are becoming increasingly brighter due to improvements in light sources or demands for improved visibility and design. The air-permeable membrane is usually fixed to a surface of the lamp other than the irradiated surface, in other words, a position that is not visible from outside the vehicle while it is in motion. However, the inventors' studies have revealed that using a white or near-white air-permeable membrane increases the likelihood of light from the light source passing through the membrane and leaking from the gap between the lamp and the body. A possible way to suppress light leakage is to use a colored air-permeable membrane. However, it is necessary to prevent the air-permeable membrane fixed to the housing from being overlooked during inspections performed during the assembly of lamps and vehicles.

[0005] The present invention aims to provide a colored breathable membrane suitable for use in light-emitting devices such as lamps. [Means for solving the problem]

[0006] The present invention provides A breathable membrane having breathability in the thickness direction, It is colored and a first main surface and a second main surface located opposite the first main surface; the second principal surface exhibits greater brightness than the first principal surface; the absolute value of the difference in brightness between the first principal surface and the second principal surface is 1.5 or more and 76 or less, the brightness of the second main surface is 20 or more and 95 or less, The breathable film has a luminous transmittance of 0.015 or less for light transmitted from the first main surface to the second main surface. However, the brightness is determined based on the CIE1976 L standard specified in JIS Z8781-4:2013. * ,a * ,b * Color space lightness L * and The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016.

[0007] From another aspect, the present invention provides a method for manufacturing a semiconductor device comprising: The breathable membrane of the present invention; and a support member that supports the breathable membrane.

[0008] From another aspect, the present invention provides a method for manufacturing a semiconductor device comprising: a housing having an opening; a light source housed in the housing; a ventilation membrane fixed to the housing so as to cover the opening, The present invention provides a light-emitting device, wherein the gas-permeable film is the gas-permeable film of the present invention. [Effects of the Invention]

[0009] In the breathable film of the present invention, the coloring is controlled so that the difference in lightness between one main surface (first main surface) and the other main surface (second main surface) is within a predetermined range, and the lightness of the second main surface, which has a relatively higher lightness, and the luminous transmittance of light transmitted from the first main surface, which has a relatively lower lightness, to the second main surface are within predetermined ranges. The breathable film with controlled coloring is suitable for achieving both the above-mentioned suppression of light leakage and prevention of oversight, and is suitable for use in light-emitting devices such as lamps. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically showing an example of the gas-permeable membrane of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating an example of a colored state in the gas-permeable membrane of the present invention. [Figure 3] FIG. 3 is a plan view schematically showing an example of the state of the second main surface of the gas-permeable membrane of the present invention. [Figure 4] FIG. 3 is a plan view schematically showing an example of the state of the second main surface of the gas-permeable membrane of the present invention. [Figure 5] FIG. 3 is a plan view schematically showing an example of the state of the second main surface of the gas-permeable membrane of the present invention. [Figure 6] FIG. 3 is a plan view schematically showing an example of the state of the second main surface of the gas-permeable membrane of the present invention. [Figure 7] FIG. 2 is a cross-sectional view schematically showing another example of the breathable membrane of the present invention. [Figure 8A] 1 is a plan view schematically illustrating an example of a ventilation member of the present invention. [Figure 8B] 8B is a cross-sectional view showing a cross section BB of the ventilation member shown in FIG. 8A. FIG. [Figure 9A] FIG. 1 is a perspective view schematically illustrating an example of a light-emitting device of the present invention. [Figure 9B] FIG. 9B is a perspective view schematically showing a state in which the breathable film is fixed in the light-emitting device shown in FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0011] The breathable membrane according to the first aspect of the present invention is A breathable membrane having breathability in the thickness direction, It is colored and a first main surface and a second main surface located opposite the first main surface; the second principal surface exhibits greater brightness than the first principal surface; the absolute value of the difference in brightness between the first principal surface and the second principal surface is 1.5 or more and 76 or less, the brightness of the second main surface is 20 or more and 95 or less, A breathable film having a luminous transmittance of 0.015 or less for light transmitted from the first main surface to the second main surface. However, the brightness is determined based on the CIE1976 L standard specified in JIS Z8781-4:2013. * ,a * ,b * Color space lightness L * and The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016.

[0012] In a second aspect of the present invention, for example, in the gas-permeable membrane according to the first aspect, the second main surface has a first circular region and a second circular region, both of which are circular and have a diameter of 6 mm, the first circular region and the second circular region are defined as a region on the second principal surface where the brightness is greatest and a region on the second principal surface where the brightness is least, respectively; The absolute value of the difference in brightness between the first circular region and the second circular region is 2.0 or more.

[0013] In a third aspect of the present invention, for example, in the breathable membrane according to the first or second aspect, the second main surface has a first band region and a second band region adjacent to the first band region and having a lower brightness than the first band region.

[0014] In a fourth aspect of the present invention, for example, the gas-permeable membrane according to any one of the first to third aspects includes a polytetrafluoroethylene (PTFE) porous membrane.

[0015] In a fifth aspect of the present invention, for example, the gas-permeable membrane according to any one of the first to fourth aspects is made of a single-layer porous polytetrafluoroethylene (PTFE) membrane.

[0016] In a sixth aspect of the present invention, for example, the breathable membrane according to any one of the first to fifth aspects includes a uniaxially stretched membrane.

[0017] In a seventh aspect of the present invention, for example, in the breathable membrane according to any one of the first to sixth aspects, the water pressure resistance evaluated by the water resistance test specified in JIS L1092:2009 is 5 kPa or more.

[0018] In an eighth aspect of the present invention, for example, in the breathable membrane according to any one of the first to seventh aspects, the breathability in the thickness direction is 200 seconds / 100 mL or less, expressed as air permeability (Gurley air permeability) evaluated in accordance with the breathability measurement method B (Gurley method) specified in JIS L1096:2010.

[0019] In a ninth aspect of the present invention, for example, the breathable membrane according to any one of the first to eighth aspects has a thickness of more than 100 μm.

[0020] A ventilation member according to a tenth aspect of the present invention comprises: A breathable membrane according to any one of the first to ninth aspects; and a support member that supports the breathable membrane.

[0021] A light-emitting device according to an eleventh aspect of the present invention comprises: a housing having an opening; a light source housed in the housing; a ventilation membrane fixed to the housing so as to cover the opening, The gas-permeable membrane is the gas-permeable membrane according to any one of the first to ninth embodiments.

[0022] In a twelfth aspect of the present invention, for example, in the light-emitting device according to the eleventh aspect, the gas-permeable film is fixed to the housing so that the first main surface faces the inside of the housing.

[0023] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0024] [Breathable membrane] An example of a breathable membrane of this embodiment is shown in FIG. 1. The breathable membrane 1 of FIG. 1 is breathable in the thickness direction and is colored. The breathable membrane 1 has a first main surface 11 and a second main surface 12 located opposite the first main surface 11. The second main surface 12 has a higher brightness than the first main surface 11. In other words, the first main surface 11 and the second main surface 12 are main surfaces having a relatively low brightness and a relatively high brightness, respectively. The absolute value d1 of the difference in brightness between the first main surface 11 and the second main surface 12 is 1.5 or more and 76 or less. The brightness of the second main surface 12 is 20 or more and 95 or less. The luminous transmittance of light transmitted from the first main surface 11 to the second main surface 12 is 0.015 or less. However, the above brightness is based on the CIE1976 L standard defined in the Japanese Industrial Standards (hereinafter referred to as JIS) Z8781-4:2013. * ,a * ,b * Color space lightness L * The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016. In the breathable membrane 1, the first main surface 11 is usually more colored than the second main surface 12. The breathable membrane 1 in FIG. 1 includes a polytetrafluoroethylene (hereinafter referred to as PTFE) porous membrane. More specifically, the breathable membrane 1 is composed of a single layer of PTFE porous membrane. The lightness L of the main surface of the uncolored PTFE porous membrane is * is usually around 93 to 97.

[0025] Lightness L *To measure the lightness, a spectrophotometer, colorimeter, or other measuring instrument conforming to the above standards can be used. * The lightness L may be calculated by converting the CIE tristimulus value Y calculated in accordance with the JIS Z8722:2009 standard using a conversion formula. * Between the stimulus value Y and the equation: L * =116(Y / Yn) 1 / 3 -16 (when Y / Yn>0.008856), or formula: L * It is known to those skilled in the art that the conversion formula Y = 903.29(Y / Yn); (when Y / Yn ≦ 0.008856) holds. Yn is measured using the same measuring device and a white reflective standard (white plate) calibrated against a perfect diffuse reflector. Measuring devices such as spectrophotometers and colorimeters that comply with the above standards can be used to measure the stimulus value Y. However, the stimulus value Y shall be determined under the following measurement conditions. ·Measurement is performed under geometric condition g (di: 0°). The diameter of the integrating sphere is 150 mm. ·Normalize the stimulus values ​​X, Y, and Z when measuring the standard white board so that they are within ±0.03 of the reference value. The light source used is auxiliary illuminant C for colorimetry as specified in JIS Z8720:2012.

[0026] Lightness L of the first principal surface 11 and the second principal surface 12 * The area of ​​the evaluation area of ​​the measuring device used to determine this (hereinafter referred to as the evaluation area) is 700 to 750 mm 2 The area of ​​the main surfaces 11 and 12 of the measurement object is small, and the evaluation area is 700 mm 2 If it is not possible to ensure this, the evaluation area may be reduced. * The evaluation is performed on at least 20% of the entire area of ​​the main surfaces 11 and 12 to be measured. An evaluation area that can achieve the evaluation at the above ratio may be set by measuring one location on the main surface, or an evaluation area that can achieve the evaluation at the above ratio may be set by evaluating multiple randomly selected locations on the main surface, and the average of the measurements at each location is used as the lightness L. * It may be determined as follows.

[0027] The luminous transmittance Y is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016. The stimulus value Y can be determined in accordance with the provisions of JIS Z8722:2009. In the evaluation of a transparent object, it is known to those skilled in the art that the stimulus value Y corresponds to the luminous transmittance. The measurement conditions for the stimulus value Y are as described above. The evaluation area for determining the luminous transmittance Y is 165 to 185 mm 2 The area of ​​the main surfaces 11 and 12 of the measurement object is small, and the evaluation area is 165 mm 2 If this ratio cannot be ensured, the evaluation area may be reduced. However, in this case, the evaluation of the luminous transmittance Y shall be carried out over at least 20% of the total area of ​​the principal surfaces 11 and 12 to be measured. An evaluation area that can achieve the evaluation at the above ratio may be set by measuring one location on the principal surface, or an evaluation area that can achieve the evaluation at the above ratio may be set by evaluating multiple randomly selected locations on the principal surface, and the average value measured at each location may be determined as the luminous transmittance Y.

[0028] The lightness L between the first principal surface 11 and the second principal surface 12 * The lower limit of the absolute value d1 of the difference may be 5 or more, 9 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 33 or more, 35 or more, 40 or more, 45 or more, 47 or more, 50 or more, 52 or more, or even 55 or more. The upper limit of the absolute value d1 may be 75 or less, 72 or less, 70 or less, 67 or less, 65 or less, 62 or less, 60 or less, or even 57 or less.

[0029] Lightness L of the second principal surface 12 * The lightness L of the second main surface 12 may be 25 or more, 28 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 52 or more, 55 or more, 57 or more, 60 or more, 62 or more, 65 or more, 67 or more, 70 or more, 72 or more, or even 75 or more. * may be less than 93, 92 or less, 91 or less, 90 or less, 88 or less, or even 86 or less. The second main surface 12 may be colored.

[0030] Lightness L of the first principal surface 11 * is, for example, less than 50, and may be 47 or less, 45 or less, 42 or less, 40 or less, 37 or less, 35 or less, 32 or less, 30 or less, 27 or less, 25 or less, 22 or less, or even 20 or less. * The lower limit is, for example, 5 or more, and may be 7 or more, 10 or more, 12 or more, 15 or more, 17 or more, 20 or more, or even 23 or more.

[0031] The luminous transmittance Y of light transmitted from the first principal surface 11 to the second principal surface 12 may be 0.013 or less, 0.011 or less, 0.010 or less, 0.008 or less, 0.006 or less, 0.005 or less, 0.003 or less, 0.002 or less, or even 0.001 or less. The lower limit of the luminous transmittance Y may be 0.000.

[0032] The luminous transmittance Y of light transmitted from the second main surface 12 to the first main surface 11 can be in the same range as the example given in the description of the luminous transmittance Y of light transmitted from the first main surface 11 to the second main surface 12.

[0033] Lightness L * The absolute value d1 of the difference between the two, and the lightness L of the second principal surface * The luminous transmittance Y of light transmitted from the first main surface 11 to the second main surface 12 can vary, for example, depending on the configuration and coloring method of the breathable membrane 1. Examples of the configuration of the breathable membrane 1 include the thickness, material, average pore size, and, if a stretched membrane is included, the stretching state and stretching method. The coloring method includes the type of colorant.

[0034] The second main surface 12 has a higher lightness L than the first main surface 11. * and the lightness L between the first main surface 11 and the second main surface 12. * The absolute value of the lightness L of the second main surface 12 is 1.5 or more and 76 or less. *The coloring state of the breathable membrane 1 is not limited as long as the luminous transmittance Y is 20 or more and 95 or less, and the luminous transmittance Y of light transmitted from the first main surface 11 to the second main surface 12 is 0.015 or less. In one example of the breathable membrane 1, when viewed in cross section in the thickness direction, the membrane is colored in a gradation pattern in which the degree of coloring gradually decreases from the first main surface 11 to the second main surface 12 (see FIG. 2).

[0035] The second main surface 12 is partially lightened with a brightness of L * This aspect can contribute to improving the visibility of the breathable membrane 1. * In one example having large and small regions (see FIG. 3), the second main surface 12 has a first circular region 21 and a second circular region 22, both of which are circular and have a diameter of 6 mm. The first circular region 21 has a lightness L * The second circular area 22 is defined as the largest area on the second main surface 12. * is defined as the smallest area. * The absolute value d2 of the difference between the lightness L and the lightness L may be 2.0 or more, 2.5 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or even 8 or more. * The upper limit of the absolute value d2 of the difference between the lightness L and the lightness L may be, for example, 76 or less, and may be 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or even 25 or less. * The area of ​​the evaluation area for measuring the absolute value d2 of the difference is 1000 mm 2 May be less than 800mm 2 Below, 600mm 2 Below, 500mm 2 Below, 400mm 2 Below, even 300mm 2 It may be less than L * The second major surface 12 having large and small areas may be visually perceived as having, for example, a mottled, marbled, rippled, or striped major surface.

[0036] As shown in FIG. 4, the first circular region 21 and the second circular region 12 may be adjacent to each other on the second main surface 12.

[0037] Partially lightened * In another example (see FIG. 5 ) having a large area and a small area, the second main surface 12 has a first band-shaped area 31 and a lighter area L 1 adjacent to the first band-shaped area 31 and having a lighter area L 2 than the first band-shaped area 31. * The first band region 31 and the second band region 32 generally have widths and lengths that are visible to the naked eye. The widths may vary along the direction in which each band region extends, and the variation may be irregular. As shown in FIG. 6 , the first band region 31 may include a first circular region 21. The second band region 32 may include a second circular region 22. The first circular region 21 included in the first band region 31 and the second circular region 22 included in the second band region 32 may be adjacent to each other on the second main surface 12. The first band region 31 and the second band region 32 may be spaced apart from each other within an area of ​​1000 mm on the second main surface 12. 2 Below, 800mm 2 Below, 600mm 2 Below, 500mm 2 Below, 400mm 2 Below, even 300mm 2 It can be in the following range:

[0038] Partially lightened * Whether the second main surface 12 has large and small regions, and if so, the configuration of each region can vary, for example, depending on the configuration of the breathable membrane 1 and the coloring method. Examples of the configuration of the breathable membrane 1 include the thickness, material, average pore size, and, if a stretched membrane is included, the stretching state and stretching method. The coloring method includes the type of colorant. According to the studies of the present inventors, when a coloring method is selected in which a dye solution is applied to one main surface of the raw membrane before coloring, the thicker the breathable membrane 1 is, and the more the breathable membrane 1 includes a uniaxially stretched membrane, the more likely it is that the second main surface 12 will have a partial brightness L. * There is a strong tendency for the saturation to have areas of high and low density.

[0039] The breathable membrane 1 in FIG. 1 includes a PTFE porous membrane. The breathable membrane 1 may include a membrane other than a PTFE porous membrane. In this specification, a porous membrane refers to a membrane having a plurality of pores that can contribute to breathability in the thickness direction. Examples of other membranes include porous membranes made of resins other than PTFE. Examples of other resins include fluororesins other than PTFE, such as polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene-ethylene copolymer, as well as polyolefins such as polyethylene, ultra-high molecular weight polyethylene, polypropylene, poly-4-methylpentene-1, and poly-1-butene. A PTFE porous membrane is particularly suitable for achieving a high balance of breathability and waterproofness in the breathable membrane 1 and for suppressing the permeation of foreign matter such as water and dust.

[0040] The average pore size of the PTFE porous membrane is, for example, 0.01 to 5 μm, and may be 2 μm or less, or even 1 μm or less. The average pore size of the PTFE porous membrane can be measured in accordance with ASTM (American Society for Testing and Materials) F316-86.

[0041] The porosity of the PTFE porous membrane is, for example, 50 to 99%. The porosity of the PTFE porous membrane 1 can be calculated by substituting the mass, thickness, area (area of ​​the main surface) and true density of the membrane into the following formula. The true density of PTFE is 2.18 g / cm 3 is. Formula: Porosity (%) = {1 - (mass [g] / (thickness [cm] × area [cm] 2 ] × true density [g / cm 3 ]))}×100

[0042] The breathable membrane 1 in FIG. 1 is a single layer. The breathable membrane 1 may be a multilayer membrane including two or more layers. The multilayer breathable membrane 1 may include one or more PTFE porous membranes, or may be composed of two or more PTFE porous membranes. FIG. 7 shows an example of a breathable membrane 1 composed of two or more PTFE porous membranes. The breathable membrane 1 in FIG. 7 includes a first PTFE porous membrane 2 and a second PTFE porous membrane 3. The main surface of the first PTFE porous membrane 2 constitutes the first main surface 11, and the main surface of the second PTFE porous membrane 3 constitutes the second main surface 12. The first PTFE porous membrane 2 is usually colored. The first PTFE porous membrane 2 and the second PTFE porous membrane 3 may be colored to different degrees. In other words, the breathable membrane 1 may include two or more PTFE porous membranes 2 and 3 having different degrees of coloration. The second PTFE porous membrane 3 may be colored or uncolored.

[0043] The breathable membrane 1 may include a uniaxially stretched membrane. A stretched membrane usually has a unique pore structure that can be changed depending on the stretching method and stretching conditions. According to the study by the present inventors, the pore structure of a uniaxially stretched membrane is such that the second main surface 12 is partially brightened with a lightness L * This can contribute to having large and small areas.

[0044] The uniaxially stretched membrane that the breathable membrane 1 may comprise may be a PTFE porous membrane. A PTFE porous membrane is typically composed of countless PTFE fine fibers (fibrils) and may have PTFE agglomerates (nodes) where multiple fibrils are connected. Fibrils are typically formed by stretching a PTFE sheet, which is an agglomerate of PTFE. A PTFE porous membrane, which is a uniaxially stretched membrane, may have a configuration in which multiple fibrils connect between relatively large nodes, depending on the stretching temperature.

[0045] The breathable film 1 may have a thickness of more than 100 μm. The thickness may be 105 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, or even 150 μm or more. The upper limit of the thickness is, for example, 5000 μm or less. However, the thickness of the breathable film 1 is not limited to the above example. According to the study by the present inventors, a large thickness of the breathable film 1 means that the second main surface 12 partially has a low brightness L. * This can contribute to having large and small areas.

[0046] The breathable membrane 1 may be waterproof. The breathable membrane 1 may have a water pressure resistance of 5 kPa or more as evaluated by a water resistance test specified in JIS L1092:2009. The water pressure resistance may be 10 kPa or more, 20 kPa or more, 30 kPa or more, 40 kPa or more, 50 kPa or more, 60 kPa or more, 70 kPa or more, 80 kPa or more, 90 kPa or more, or even 100 kPa or more. The upper limit of the water pressure resistance may be 400 kPa or less. The water pressure resistance may be a value when the first main surface 11 is the surface to which water pressure is applied during testing.

[0047] The water pressure resistance of the breathable membrane 1 can be measured using a measuring jig in accordance with the above-mentioned water resistance test method as follows. An example of the measuring jig is a stainless steel disk with a diameter of 47 mm and a through-hole (with a circular cross section) with a diameter of 2 mm at the center. This disk has a thickness that does not deform due to the water pressure applied when measuring the water pressure. Measurement of the water pressure resistance using this measuring jig can be carried out as follows.

[0048] The breathable membrane 1 to be evaluated is fixed to one side of the measurement jig so as to cover the opening of the through-hole. Fixation is performed so that water does not leak from the fixed part of the membrane during water pressure resistance measurement. The breathable membrane 1 can be fixed using double-sided adhesive tape with a water-passing hole punched in the center, whose shape matches the opening. The double-sided adhesive tape is simply placed between the measurement jig and the breathable membrane 1 so that the circumference of the water-passing hole coincides with the circumference of the opening. Next, the measurement jig with the breathable membrane 1 fixed is set in the testing device so that the surface opposite the fixed surface of the breathable membrane 1 becomes the surface to which water pressure is applied during measurement, and the water pressure resistance is measured according to Water Resistance Test Method A (low water pressure method) or Method B (high water pressure method) specified in JIS L1092:2009. However, the water pressure resistance is measured based on the water pressure when water leaks from one point on the membrane surface of the breathable membrane 1. The measured water pressure resistance can be used as the water pressure resistance of the breathable membrane 1. The test device may have the same configuration as the water resistance test device exemplified in JIS L1092:2009 and have a test piece mounting structure to which the above-mentioned measuring jig can be set.

[0049] The air permeability in the thickness direction of the breathable membrane 1 is expressed as air permeability (Gurley air permeability) determined in accordance with Air Permeability Measurement Method B (Gurley method) specified in JIS L1096:2010, and may be, for example, 200 seconds / 100 mL or less, 150 seconds / 100 mL or less, 100 seconds / 100 mL or less, 75 seconds / 100 mL or less, 50 seconds / 100 mL or less, 45 seconds / 100 mL or less, 40 seconds / 100 mL or less, 35 seconds / 100 mL or less, 30 seconds / 100 mL or less, 25 seconds / 100 mL or less, 20 seconds / 100 mL or less, or even 18 seconds / 100 mL or less. The lower limit of the Gurley air permeability is, for example, 0.5 seconds / 100 mL or more, and may be 1 second / 100 mL or more, 3 seconds / 100 mL or more, 5 seconds / 100 mL or more, 8 seconds / 100 mL or more, or even 10 seconds / 100 mL or more. The Gurley air permeability may be a value when the first main surface 11 is used as the pressure application surface during testing.

[0050] Even if the size of the breathable membrane 1 is smaller than the recommended size (approximately 50 mm x 120 mm) of a test piece in the Gurley method, the Gurley air permeability can be evaluated by using a measuring jig. An example of the measuring jig is a polycarbonate disk with a thickness of 2 mm and a diameter of 47 mm, and a through-hole (having a circular cross section with a diameter of 1 mm or 2 mm) formed in the center. Measurement of the Gurley air permeability using this measuring jig can be carried out as follows.

[0051] The breathable membrane 1 to be evaluated is fixed to one side of the measurement jig so as to cover the opening of the through-hole in the measurement jig. The fixation is performed so that during the measurement of the Gurley air permeability, air passes only through the opening and the effective test portion of the breathable membrane 1 to be evaluated (the portion overlapping with the opening when viewed perpendicularly to the main surface of the fixed breathable membrane 1), and the fixed portion does not obstruct the passage of air through the effective test portion of the breathable membrane 1. To fix the breathable membrane 1, double-sided adhesive tape with a vent hole punched in the center that matches the shape of the opening can be used. The double-sided adhesive tape can be placed between the measurement jig and the breathable membrane 1 so that the periphery of the vent hole matches the periphery of the opening. Next, the measurement jig with the breathable membrane 1 fixed is set in a Gurley air permeability tester so that the fixed surface of the breathable membrane 1 is downstream of the air flow during measurement, and the time t1 required for 100 mL of air to pass through the breathable membrane 1 is measured. Next, the measured time t1 was measured using an effective test area of ​​642 mm2 as specified in the air permeability measurement method B (Gurley method) of JIS L1096:2010. 2 ] per unit area of ​​the effective test part of the breathable membrane [mm 2 ]) / 642[mm 2 ]}, and the resulting converted value t can be used as the Gurley air permeability of the breathable membrane 1. When the above-mentioned circular plate is used as the measuring jig, the area of ​​the effective test portion of the breathable membrane 1 is the area of ​​the cross section of the through-hole. It has been confirmed that the Gurley air permeability measured without using a measuring jig for a breathable membrane 1 that meets the size of the above-mentioned test piece agrees well with the Gurley air permeability measured using the measuring jig after cutting the breathable membrane 1 into small pieces, i.e., that the use of the measuring jig does not substantially affect the measured value of the Gurley air permeability.

[0052] The breathable membrane 1 is typically colored black or gray, but the color is not limited to the above examples.

[0053] The colorant may be a dye or a pigment, but is preferably a dye from the viewpoint of preventing it from falling off from the breathable membrane 1. Falling off from the breathable membrane 1 may cause discoloration, and if the colorant is conductive, damage to electrical circuits or electronic components located near the breathable membrane 1. Furthermore, when the colorant is a dye or an insulating pigment, the breathable membrane 1 can be made insulating, depending on the material of the breathable membrane 1. The insulating property can be achieved by, for example, a 1×10 14 It is expressed by a surface resistivity of Ω / □ or more. Surface resistivity is 1×10 15 Ω / □ or more, 1×10 16 Ω / □ or more, even 1×10 17 It may be Ω / □ or more.

[0054] Examples of dyes include azo dyes and oil-soluble dyes, and examples of pigments include carbon black and metal oxides, but the dyes and pigments are not limited to these examples.

[0055] The shape of the breathable membrane 1 is, for example, a polygon including a square and a rectangle, a circle, an ellipse, an irregular shape, or a strip shape when viewed from a direction perpendicular to the first main surface 11 and the second main surface 12. However, the shape of the breathable membrane 1 is not limited to the above examples.

[0056] The gas-permeable membrane 1 may be subjected to a liquid-repellent treatment. The liquid-repellent treatment can be carried out by a known method. The liquid-repellent treatment includes a water-repellent treatment and an oil-repellent treatment. The gas-permeable membrane 1 may be a membrane that has not been subjected to a liquid-repellent treatment.

[0057] The breathable film 1 can be used, for example, as a film that allows gas to pass through while blocking foreign matter such as water and dust. Examples of breathable films include a waterproof film that is placed in an opening in the housing of a light-emitting device such as a lamp and allows gas to pass through while preventing water from entering through the opening, and a dustproof film that is placed in the opening and allows gas to pass through while preventing dust from entering through the opening. The light-emitting device is not limited to a lamp. Furthermore, the housing in which the breathable film 1 is placed may be the housing of an electronic device or electronic component other than a light-emitting device. The uses of the breathable film 1 are not limited to the above examples. The breathable film 1 can be a film that has a relatively high brightness L * The first main surface 12 having the smaller diameter may be disposed at the opening so as to face the inside of the housing. This arrangement is particularly suitable for suppressing light leakage from the light-emitting device through the gas-permeable film 1.

[0058] The breathable membrane 1 can be produced, for example, by applying a coloring liquid containing a colorant to one main surface of the raw membrane before coloring, and then removing the solvent or dispersion medium (hereinafter, the solvent and dispersion medium will be collectively referred to as "solvent") contained in the dyeing liquid by drying or the like. A known application method can be used for the application. However, the method for producing the breathable membrane 1 is not limited to the above example. The main surface to which the coloring liquid is applied (coated surface) has a relative brightness L * This can be the first main surface 11 having the smallest diameter.

[0059] The coloring liquid may not contain a liquid repellent agent. Although it depends on the material of the breathable membrane 1, if the coloring liquid contains a liquid repellent agent, the wettability of the coloring liquid with respect to the base membrane is increased, and the brightness L * It can be difficult to increase the difference.

[0060] When the colorant is a dye, the concentration of the dye in the coloring liquid (dyeing liquid) may be, for example, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, or even 4.5% by weight or more.

[0061] When the coloring liquid contains a liquid repellent agent, the amount of the liquid repellent agent blended may be, for example, less than 20 parts by weight, 18 parts by weight or less, or even 16 parts by weight or less, relative to 100 parts by weight of the coloring agent.

[0062] The base film can be formed by a known method. For example, the base film, which is a PTFE porous film, can be formed by extruding and rolling a mixture of PTFE fine powder and a molding aid into a sheet, removing the molding aid, and then stretching the sheet. The stretching may be uniaxial stretching. The stretching may be performed at a temperature above the melting point of PTFE.

[0063] [Ventilation material] An example of a ventilation member of this embodiment is shown in FIGS. 8A and 8B. FIG. 8B shows a cross section BB of the ventilation member 4 of FIG. 8A. The ventilation member 4 of FIGS. 8A and 8B includes a ventilation membrane 1 and a support member 5 that supports the ventilation membrane 1. In the example of FIGS. 8A and 8B, the shape of the ventilation membrane 1 is rectangular when viewed from a direction perpendicular to the first main surface 11 and the second main surface 12. The shape of the support member 5 corresponds to the shape of the peripheral edge of the ventilation membrane 1 when viewed from the same direction, and specifically, is a frame shape. However, the shapes of the ventilation membrane 1 and the support member 5 are not limited to the above example, as long as the support member 5 can support the ventilation membrane 1. A ventilation member 4 including the support member 5 can reinforce the ventilation membrane 1 and improve handleability. Furthermore, the support member 5 can serve as an attachment for the ventilation membrane 1.

[0064] The material of the support member 5 is typically a resin, a metal, or a composite material thereof. The support member 5 may also be a double-sided adhesive tape.

[0065] The breathable membrane 1 and the support member 5 can be laminated together by various joining methods such as thermal lamination, heat welding, ultrasonic welding, and joining with an adhesive or pressure sensitive adhesive.

[0066] 8A and 8B, the support member 5 is disposed on one side of the breathable membrane 1. The support member 5 may be disposed on both sides of the breathable membrane 1.

[0067] The ventilation member 4 may be a waterproof member that includes the breathable membrane 1 as a waterproof membrane. The ventilation member 4 may be a dustproof member that includes the breathable membrane 1 as a dustproof membrane.

[0068] [Light-emitting device] An example of a light-emitting device of this embodiment is shown in Figs. 9A and 9B. The light-emitting device shown in Figs. 9A and 9B is a lamp 41 for a vehicle. Fig. 9A shows the lamp 41 as seen from the side of the irradiation surface 42. Fig. 9B shows the lamp 41 as seen from the side opposite the irradiation surface 42. Two openings 44 are provided in the housing 43 of the lamp 41, and a breathable membrane 1 is fixed so as to cover each opening 44. The breathable membrane 1 has a relative brightness L * The lamp 41 is fixed to the housing 43 so that the small first main surface 11 faces the inside of the housing 43. The breathable membrane 1 covers the opening 44 from the outside of the housing 43. In the lamp 41, the breathable membrane 1 is fixed, thereby suppressing the transmission of light from the light source 45 through the opening 44. Furthermore, the breathable membrane 1 has the second main surface 12 facing the outside of the housing 43, making it suitable for visual confirmation when inspecting the lamp 41.

[0069] Examples of the light-emitting device are lamps, signal lights, and backlights for electronic devices such as cameras and displays. The light-emitting device may be for a vehicle. However, the light-emitting device is not limited to the above examples. [Example]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0071] [Evaluation method] The method for evaluating the breathable membrane produced in this example will be described below.

[0072] (Lightness L * ) Lightness of the main surface L * The stimulus value Y of the CIE tristimulus values ​​was measured using a spectrophotometer (SE6000, manufactured by Nippon Denshoku Industries Co., Ltd.) that can be evaluated in accordance with the JIS Z8722:2009 standard, and this was converted into the L * =116(Y / Yn) 1 / 3 -16 by L * The lightness L *The evaluation was carried out for each of the first principal surface 11 and the second principal surface 12. The measurement conditions were as described above. * The evaluation area for determining this is a circle with a diameter of 30 mm (area 706.5 mm 2 ) was decided.

[0073] The lightness L of the first circular region 21 and the second circular region 22 on the second main surface 12 * Each evaluation area is a circle with a diameter of 6 mm (area of ​​28.3 mm 2 ) except for the lightness L of the main surface * was similarly sought.

[0074] (Luminous transmittance Y) The luminous transmittance Y was determined by measuring the CIE tristimulus stimulus value Y using a spectrophotometer (Murakami Color Research Laboratory, integrating sphere spectral transmittance measuring instrument DOT-3C) capable of evaluation in accordance with the provisions of JIS Z8722:2009. The evaluation was performed on the light transmitted from the first principal surface 11 to the second principal surface 12, and on the light transmitted from the second principal surface 12 to the first principal surface 11. The measurement conditions were as described above. The evaluation area for determining the luminous transmittance Y was a circle with a diameter of 15 mm (area 176.6 mm 2 ) was decided.

[0075] (Water pressure resistance) The water pressure resistance (limiting water pressure resistance) was evaluated by the method described above. The evaluation was carried out with the first main surface 11 as the water pressure application surface.

[0076] (Air permeability in the thickness direction) The air permeability in the thickness direction was evaluated as Gurley air permeability by the method described above. The evaluation was carried out with the first main surface 11 as the pressure application surface.

[0077] [Preparation of base film] (Base film A) 100 parts by weight of PTFE fine powder (manufactured by AGC, CD123E) and 20 parts by weight of ISOPAR M (manufactured by Ando Bakeramy) as a molding aid were uniformly mixed, and the resulting mixture was compressed using a cylinder and then ram extrusion molded into a sheet. Next, the sheet-like mixture was rolled through a pair of metal rolls to a thickness of 0.24 mm, and then heated to 170 ° C to dry and remove the molding aid, resulting in a sheet molded product. Next, the sheet molded product was stretched in the longitudinal direction (rolling direction) at a stretching temperature of 380 ° C and a stretching ratio of 4.2 times to obtain a PTFE porous membrane as base membrane A. The resulting porous membrane was a uniaxially stretched membrane.

[0078] (Protofilm B) 100 parts by weight of PTFE fine powder (Daikin Industries, F104) and 20 parts by weight of n-dodecane (Japan Energy) as a molding aid were uniformly mixed, and the resulting mixture was compressed using a cylinder and then ram-extruded to form a sheet. Next, the sheet-like mixture was rolled through a pair of metal rolls to a thickness of 0.2 mm, then stretched 4.5 times in the width direction, and further heated to 150 ° C to dry and remove the molding aid, resulting in a sheet molded product. Next, the sheet molded product was stretched in the longitudinal direction (rolling direction) at a stretching temperature of 300 ° C and a stretching ratio of 4 times, then stretched in the width direction at a stretching temperature of 150 ° C and a stretching ratio of 25 times, and further calcined at 400 ° C to obtain a PTFE porous membrane as base membrane B. The resulting porous membrane was a biaxially stretched membrane.

[0079] (Examples 1 to 5, 7 to 8, Comparative Examples 2 to 4) A mixture of a black dye (SP BLACK 91L, manufactured by Orient Chemical Industry Co., Ltd., dye concentration 25% by weight) and a solvent was prepared as the dye solution. The solvent was added so that the dye concentration (solid content concentration; the same applies hereinafter) in the dye solution would be the value shown in Table 1 below. The solvent was methyl ethyl ketone (MEK). Next, the prepared dye solution was applied to one main surface of raw membrane A, and then the membrane was naturally dried in an atmosphere of 20°C and a relative humidity of 50%, to obtain the breathable membranes of Examples 1 to 5, 7 to 8 and Comparative Examples 2 to 4 colored with the dye. The dye solution was applied using an applicator to the coating thickness shown in Table 1.

[0080] [Table 1]

[0081] Example 6 A load was applied in the thickness direction to the laminate of the breathable membrane of Comparative Example 4 and the base membrane A by moving a roller weighing 2 kg back and forth once to obtain the breathable membrane of Example 6, which is composed of two layers of PTFE porous membrane.

[0082] (Comparative Example 1) A mixture of a black dye (SP BLACK 91L, manufactured by Orient Chemical Industry Co., Ltd., dye concentration 25 wt%) and a solvent was prepared as the dye solution. The solvent was added so that the dye concentration in the dye solution was 2.1 wt%. The solvent was a mixed solution of toluene and methyl ethyl ketone (MEK). The mixing ratio, expressed by volume, was toluene:MEK = 75:25. Next, the prepared dye solution was applied to one main surface of raw membrane B, and then air-dried in an atmosphere of 20°C and relative humidity 50%, to obtain a breathable membrane of Comparative Example 1 colored with the above dye. The dye solution was applied using an applicator to a coating thickness of 17 μm.

[0083] (Comparative Example 5) The raw film A was used as Comparative Example 5.

[0084] The evaluation results for each of the breathable membranes of the Examples and Comparative Examples are shown in Tables 2A and 2B below.

[0085] [Table 2A]

[0086] [Table 2B]

[0087] Next, for the breathable membranes of Examples 1, 7, and 8 and Comparative Example 1, the lightness L of the first circular region and the second circular region on the second main surface was measured. *The evaluation results are shown in Table 3 below. The lightness L of the first circular area and the second circular area * In the evaluation of the brightness L, two more circular areas (third and fourth circular areas; both 6 mm in diameter) were randomly set and the brightness L * Table 3 shows the brightness of the circular area L * is also shown.

[0088] [Table 3] [Industrial Applicability]

[0089] The breathable membrane of the present invention can be used in the same applications as conventional breathable membranes.

Claims

1. A breathable membrane having breathability in the thickness direction, It is composed of a single layer of polytetrafluoroethylene (PTFE) porous membrane, having a thickness of more than 100 μm, It is colored and a first major surface and a second major surface opposite the first major surface; the second principal surface exhibits greater brightness than the first principal surface; an absolute value of the difference in brightness between the first principal surface and the second principal surface is 1.5 or more and 76 or less; the brightness of the second main surface is 20 or more and 95 or less, A breathable film having a luminous transmittance of light transmitted from the first main surface to the second main surface of 0.015 or less. However, the brightness is determined based on the CIE1976 L standard defined in JIS Z8781-4:2013. * , a * , b * Color space lightness L * and The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016.

2. the second main surface has a first circular region and a second circular region, each of which is circular and has a diameter of 6 mm; the first circular region and the second circular region are defined as a region on the second principal surface where the brightness is greatest and a region on the second principal surface where the brightness is least, respectively; The breathable membrane according to claim 1 , wherein the absolute value of the difference in brightness between the first circular region and the second circular region is 2.0 or more.

3. The breathable membrane according to claim 1 , wherein the second main surface has a first band region and a second band region adjacent to the first band region and having a lower brightness than the first band region.

4. The breathable membrane of claim 1 , comprising a uniaxially stretched membrane.

5. The breathable membrane according to claim 1, having a water pressure resistance of 5 kPa or more as evaluated by a water resistance test specified in JIS L1092:2009.

6. 2. The breathable membrane according to claim 1, wherein the breathability in the thickness direction is expressed as an air permeability (Gurley air permeability) evaluated in accordance with the breathability measurement method B (Gurley method) defined in JIS L1096:2010, and is 200 seconds / 100 mL or less.

7. The breathable membrane according to any one of claims 1 to 6, a support member that supports the breathable membrane.

8. a housing having an opening; a light source housed in the housing; a ventilation membrane fixed to the housing so as to cover the opening, A light-emitting device, wherein the breathable film is the breathable film according to any one of claims 1 to 6.

9. The light-emitting device according to claim 8 , wherein the air-permeable film is fixed to the housing such that the first main surface faces the inside of the housing.

10. A housing having an opening; a light source housed in the housing; a ventilation membrane fixed to the housing so as to cover the opening, The breathable membrane is It has breathability in the thickness direction, It is colored and a first major surface and a second major surface opposite the first major surface; the first main surface is fixed to the housing so as to face the inside of the housing; Regarding the breathable membrane, the second principal surface exhibits greater brightness than the first principal surface; an absolute value of the difference in brightness between the first principal surface and the second principal surface is 1.5 or more and 76 or less; the brightness of the second main surface is 20 or more and 95 or less, a luminous transmittance of light transmitted from the first principal surface to the second principal surface of 0.015 or less; Light-emitting device. However, the lightness is the lightness L* in the CIE1976 L*, a*, b* color space defined in JIS Z8781-4:2013, The luminous transmittance is expressed by the stimulus value Y of the CIE tristimulus values ​​defined in JIS Z8781-3:2016.

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