WO2022131377A1

WO2022131377A1 - Gas-permeable waterproof sheet

Info

Publication number: WO2022131377A1
Application number: PCT/JP2021/046842
Authority: WO
Inventors: 魏呉; 直人木藤; 浩義曽田
Original assignee: エム・テックス株式会社
Priority date: 2020-12-17
Filing date: 2021-12-17
Publication date: 2022-06-23
Also published as: JPWO2022131377A1

Abstract

This gas-permeable waterproof sheet is configured from an assembly of fine fibers which comprise a lipophilic material, have a fiber diameter in a prescribed range and are irregularly interwoven with one another. The center fiber diameter is preferably 1,000-3,000nm. The coefficient of variation in the fiber diameter quantity distribution is preferably 0.5-0.65. The bulk density of the assembly is preferably 0.01-0.10 g/cm3. At least part of the fiber assembly may be covered by a cover sheet through which a gas can pass. The cover sheet is preferably a nonwoven fabric or a mesh. As a result, the present invention provides an easily producible gas-permeable waterproof sheet which has a simple structure (in other words, a sheet-like member through which a gas such as air or water vapor passes, but through which water does not pass).

Description

Breathable tarpaulin

The present invention relates to a breathable tarpaulin. More specifically, the present invention relates to a waterproof sheet through which a gas such as water vapor and air can permeate and water as a liquid cannot permeate.

For example, in the so-called "bag cultivation" in a vegetable garden or the like, plants such as vegetables and / or fruits are cultivated by the potting soil contained in a container made of a resin bag such as polyethylene. Since such a resin bag generally does not allow a liquid such as water to pass through, it has a high ability to hold water supplied to the potting soil. However, since such a resin bag does not have sufficient air permeability, it is difficult to supply oxygen into the container and / or discharge gas generated from plants (for example, ethylene gas) to the outside of the container. As a result, there is a risk of leading to problems such as damage to the roots of plants and rotting.

In addition, for example, for greening of deserts and / or prevention of salt damage in agricultural land, plants such as vegetables and / or fruits are cultivated by soil arranged on a water retention sheet laid on cultivated land. Even in this case, since the water-retaining sheet does not allow liquid or gas to pass through, it has a high ability to retain the water supplied to the soil, but it may lead to problems such as damage to the roots of plants and / or rot.

On the other hand, in the technical field, members have been developed that allow gas such as water vapor to pass through but do not allow liquid such as water to pass through in various applications. For example, a moisture-permeable waterproof sheet obtained by laminating a non-porous film made of a block copolymerized polyester having a hard segment and a soft segment and a polyester-based non-woven fabric having a predetermined fiber diameter and texture without using an adhesive is known. (See, for example, Patent Document 1). According to this, it is said that it is possible to provide a thin and lightweight moisture-permeable waterproof sheet having both excellent moisture permeability and waterproofness and excellent productivity.

Further, a wooden structure obtained by applying a hot melt adhesive to a first non-woven sheet to form a moisture-permeable adhesive uncured film and then curing the hot melt adhesive by a step of laminating and crimping the second non-woven sheet. Breathable waterproof sheets for houses are known (see, for example, Patent Document 2). According to this, it is said that a moisture-permeable waterproof sheet having high waterproofness and moisture permeability and excellent strength and durability can be manufactured inexpensively and quickly.

Further, it is known that a layer made of water-repellent sand obtained by applying a water-repellent coating to the surface of sand particles has waterproofness and moisture permeability (see, for example, Non-Patent Document 1). By laying the layer of water-repellent sand under the soil, the permeated water that has permeated the soil layer is collected and used as irrigation water, or by passing water vapor through the layer of water-repellent sand, seawater It is known that it can be used for desalination (see, for example, Non-Patent Document 2).

However, the moisture-permeable waterproof sheet having the above-mentioned laminated structure has a complicated manufacturing process, which may lead to problems such as a decrease in production efficiency and / or an increase in manufacturing cost. Further, for particles having a water-repellent coating such as the above-mentioned water-repellent sand, it is necessary to appropriately lay a layer composed of the particles so that the target soil is surrounded by the moisture-permeable waterproof layer. be. Therefore, for example, it may lead to problems such as complicated laying work and / or an increase in laying cost. Further, as compared with the sheet-like member such as the moisture-permeable waterproof sheet described above, it is difficult to construct a container such as a bag for accommodating the potting soil as described above with water-repellent sand.

Japanese Unexamined Patent Publication No. 2002-337294 Japanese Unexamined Patent Publication No. 2020-6686

As described above, in the art, a breathable waterproof sheet having a simple structure and easily manufactured (that is, a sheet-like member that allows gas such as water vapor and air to pass through but does not allow water to pass through). ) Is required.

In view of the above problems, as a result of diligent research, the present inventor has made a sheet made of a polymer material having an oil-friendly property and a fiber aggregate having a structure in which fine fibers having a predetermined fiber diameter are irregularly entangled with each other. We succeeded in solving the above-mentioned problems by using the shaped members.

Specifically, the breathable waterproof sheet according to the present invention (hereinafter, may be referred to as "the sheet of the present invention") is made of a first material which is a polymer material having lipophilicity and has a diameter of 300 nm or more. Moreover, it is a breathable waterproof sheet containing a fiber aggregate which is an aggregate of the first fiber which is a fiber having a fiber diameter of less than 5000 nm. In the fiber aggregate, the first fibers are irregularly entangled with each other. Preferably, the central fiber diameter, which is the mode in the quantity distribution of the fiber diameter of the first fiber, is 800 nm or more and 3000 nm or less. More preferably, the coefficient of variation in the quantity distribution of the fiber diameter of the first fiber is 0.50 or more and 0.65 or less. More preferably, the bulk density of the fiber aggregate is 0.01 g / cm ³ or more and 0.10 g / cm ³ or less.

As described above, the sheet of the present invention contains a fiber aggregate which is an aggregate in which first fibers which are fine fibers having a predetermined fiber diameter and which are made of a polymer material having lipophilicity are irregularly entangled with each other. Become. Preferably, the central fiber diameter, which is the mode in the quantity distribution of the fiber diameter of the first fiber, is 800 nm or more and 3000 nm or less. More preferably, the coefficient of variation in the quantity distribution of the fiber diameter of the first fiber is 0.50 or more and 0.65 or less. More preferably, the bulk density of the fiber aggregate is 0.01 g / cm ³ or more and 0.10 g / cm ³ or less. As a result, the sheet of the present invention allows gas such as water vapor and air to pass through, but does not allow water to pass through. That is, according to the sheet of the present invention, a breathable waterproof sheet having a simple structure and easily manufactured (that is, a sheet-like member that allows gas such as water vapor and air to pass through but does not allow water to pass through). Can be provided.

It is a photograph which shows an example of the appearance of the fiber aggregate which constitutes the breathable waterproof sheet (first sheet) which concerns on 1st Embodiment of this invention. 6 is a scanning electron microscope (SEM) photograph showing an example of the structure of the fiber aggregate constituting the first sheet. It is a schematic graph which shows two examples of the quantity distribution of the fiber diameter of the 1st fiber which constitutes the fiber accumulation of the breathable waterproof sheet (the 2nd sheet) which concerns on the 2nd Embodiment of this invention. It is a schematic graph which shows two examples of the quantity distribution of the fiber diameter of the fiber which constitutes the fiber accumulation of the breathable waterproof sheet which does not correspond to this invention. Distribution of fiber diameters of fibers contained in the fiber aggregate constituting the breathable waterproof sheet (third sheet) according to the third embodiment of the present invention and the non-woven fabric constituting the breathable waterproof sheet (conventional sheet) according to the prior art. It is a schematic graph showing. It is a schematic perspective view which shows an example of the structure of the experimental apparatus for evaluating the waterproof breathability of the breathable waterproof sheet (the sheet of this invention) which concerns on this invention. It is a graph which shows the relationship between the thickness of the test piece which consists of the fiber aggregate constituting the breathable waterproof sheet which has various central fiber diameters, and the ventilation start pressure. It is a graph which shows the relationship between the bulk density of the test piece which consists of the fiber aggregates having various central fiber diameters, and the aeration start pressure. It is a graph which shows the relationship between the bulk density of the test piece which consists of a fiber aggregate constituting 4th sheet, and the aeration start pressure.

<< First Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “first sheet”) according to the first embodiment of the present invention will be described.

<Constitution>
The first sheet comprises a fiber aggregate which is an aggregate of the first fiber which is a fiber having a fiber diameter of 300 nm or more and less than 5000 nm, which is made of the first material which is a polymer material having lipophilicity. It is a breathable waterproof sheet. The first material is not particularly limited as long as it is a polymer material having lipophilicity and can withstand the usage environment and usage conditions as a breathable waterproof sheet. Specific examples of the first material include polyolefins and the like. Typically, the first material is at least one polymeric material selected from the group consisting of polyethylene, polypropylene and polybutylene. Further, the first material may be a combination of a plurality of different types of polymer materials having lipophilicity. Further, the first fiber may be a combination of fibers made of a plurality of different lipophilic polymer materials. In addition, the fiber aggregate may contain a small amount of fibers made of a polymer material different from the first material, as long as the overall breathability and waterproofness of the fiber aggregate are not impaired.

The fiber diameter of the first fiber constituting the fiber aggregate can be measured, for example, by image analysis of the fiber aggregate taken by a scanning electron microscope (SEM). For example, the distribution of the number of imaging points with respect to the average value of the fiber diameters measured at each of the plurality of imaging points may be regarded as the quantity distribution of the fiber diameter. As described above, the fiber diameter of the first fiber is 300 nm or more and less than 5000 nm. The first fiber having a fiber diameter within this range is capable of stable production and can simultaneously achieve good air permeability and good waterproof property in the first sheet.

Furthermore, in the fiber aggregate, the first fibers are irregularly entangled with each other. In the present specification, the state in which the first fibers are entangled irregularly means that the entanglement of the first fibers is not a simple entanglement due to, for example, twisting in a specific direction, but the first fibers are tertiary. It means a state of being intertwined in an original and complicated manner. Thereby, the first sheet can simultaneously achieve good breathability and good waterproofness.

FIG. 1 is a photograph showing an example of the appearance of the fiber aggregate constituting the first sheet, and FIG. 2 is a scanning electron microscope (SEM) photograph showing an example of the structure of the fiber aggregate constituting the first sheet. .. The fiber aggregates constituting the first sheet illustrated in FIG. 1 (a) have a substantially lumpy appearance, but the fiber aggregates actually contained in the first sheet are exemplified in FIG. 1 (b). It is formed into a sheet-like shape so as to be used. In FIGS. 1 and 2, as an example of the fiber aggregate constituting the first sheet, an external photograph and an SEM photograph of the fiber aggregate made of polypropylene fibers having a fiber diameter of 300 nm to 5000 nm are exemplified. .. That is, in this example, the first material is polypropylene, and the first fiber is a polypropylene fiber having the above fiber diameter. As can be seen from FIG. 2, in the fiber aggregate constituting the first sheet, the first fibers are irregularly entangled with each other.

As described above, the fiber aggregate constituting the first sheet is made of the first material which is a lipophilic polymer material and has a fiber diameter of 300 nm or more and less than 5000 nm. Is entwined irregularly. As a result, according to the first sheet, good breathability and good waterproofness can be achieved at the same time.

The fiber aggregate constituting the first sheet shall be manufactured by applying a fine fiber manufacturing method widely adopted in the technical field, such as the so-called "melt blow method" and "dry spinning method". Can be done. Since the details of the "melt blow method" and the "dry spinning method" are well known to those skilled in the art, the description thereof is omitted here. In these manufacturing methods, in the process of producing the first fiber, which is a fine fiber made of the first material, the first fibers are irregularly entangled with each other to obtain a fiber aggregate as described above. can.

<effect>
As described above, the fiber aggregate constituting the first sheet is made of the first material which is a lipophilic polymer material and has a fiber diameter of 300 nm or more and less than 5000 nm. Is entwined irregularly. As a result, according to the first sheet, good breathability and good waterproofness can be achieved at the same time. Further, the fiber aggregate constituting the first sheet shall be manufactured by applying a fine fiber manufacturing method widely adopted in the technical field, such as the so-called "melt blow method" and "dry spinning method". Can be done. That is, according to the first sheet, a breathable waterproof sheet having a simple structure and easily manufactured (that is, a sheet-like member that allows gas such as water vapor and air to pass through but does not allow water to pass through). Can be provided.

<< Second Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “second sheet”) according to the second embodiment of the present invention will be described.

As described above, the fiber aggregate constituting the first sheet is made of the first material which is a lipophilic polymer material and has a fiber diameter of 300 nm or more and less than 5000 nm. Is entwined irregularly. As a result, according to the first sheet, good breathability and good waterproofness can be achieved at the same time. As a result of further research, the present inventor has found that the above effect is more remarkably achieved when the mode value in the quantity distribution of the fiber diameter of the first fiber constituting the fiber aggregate is within a predetermined range. I found it.

<Constitution>
The second sheet is the above-mentioned first sheet, and is a breathable waterproof sheet characterized in that the central fiber diameter of the first fiber constituting the fiber aggregate is 800 nm or more and 3000 nm or less. Here, the "central fiber diameter" is the mode in the quantity distribution of the fiber diameter of the first fiber constituting the fiber aggregate. In other words, the "central fiber diameter" means the fiber diameter having the highest frequency of appearance in the quantity distribution of the fiber diameter of the first fiber.

FIG. 3 is a schematic graph showing two examples of the quantity distribution of the fiber diameters of the first fibers constituting the fiber aggregate of the second sheet. In such a graph, a scanning electron microscope (SEM) photograph is taken at a plurality of points of the fiber aggregate, and the average value of the fiber diameters measured by image analysis for each point is calculated as the fiber diameter at each place. It can be obtained by graphing the relationship between the calculated fiber diameter and the frequency of appearance (number of imaging locations). That is, the horizontal axis and the vertical axis of the graph illustrated in FIG. 3 represent the appearance frequency (number of imaging locations) and the fiber diameter, respectively, and the graph shows the quantity distribution of the fiber diameter of the first fiber.

In FIG. 3A, the first fiber having a central fiber diameter of 800 nm, which is the fiber diameter having the highest frequency of appearance (number of imaging locations) (that is, the most frequent value in the quantity distribution of the fiber diameter of the first fiber). The quantity distribution of the fiber diameter in the fiber aggregate composed of is shown. FIG. 3B shows the quantity distribution of fiber diameters in the fiber aggregate composed of the first fibers having a central fiber diameter of 1500 nm. In the fiber aggregate constituting the second sheet, the central fiber diameter that can be specified as described above is within the range of 800 nm or more and 3000 nm or less. Thereby, the second sheet can simultaneously achieve good breathability and good waterproofness at a higher level.

On the other hand, FIG. 4 is a schematic graph showing two examples of the quantity distribution of the fiber diameters of the fibers constituting the fiber aggregate of the breathable waterproof sheet which does not correspond to the present invention. FIG. 4A shows the quantity distribution of the fiber diameter in the fiber aggregate composed of the first fiber having the central fiber diameter of 4500 nm. FIG. 4B shows the quantity distribution of the fiber diameters of the fibers contained in the nonwoven fabric constituting the breathable waterproof sheet (hereinafter, may be referred to as “conventional sheet”) according to the prior art. As shown in FIG. 4B, the nonwoven fabric is composed of fibers having a central fiber diameter of 20 μm (= 20000 nm). As described above, in the fiber aggregate having a central fiber diameter of 800 nm or more and not in the range of 3000 nm or less, good air permeability and good waterproofness are simultaneously achieved at a high level such as the second sheet. Cannot be achieved. In particular, the non-woven fabric constituting the conventional sheet illustrated in FIG. 4B exhibits waterproofness by itself (that is, in a state where it is not laminated with a waterproof layer such as a non-porous film as described above). I can't.

The "center fiber diameter" of the first fiber is, for example, the temperature and discharge amount of the first liquid which is a liquid containing the first material and the first liquid contained in the discharged first liquid in the process of manufacturing the fiber aggregate. It can be changed by adjusting the manufacturing conditions such as the temperature and the flow velocity of the gas that conveys the material to the downstream side while stretching it in a thread shape.

<effect>
As described above, in the second sheet, the central fiber diameter of the first fiber constituting the fiber aggregate is 800 nm or more and 3000 nm or less. As a result, according to the second sheet, good breathability and good waterproofness can be achieved at a higher level at the same time.

<< Third Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “third sheet”) according to the third embodiment of the present invention will be described.

As described above, in the second sheet, the central fiber diameter of the first fiber constituting the fiber aggregate is 800 nm or more and 3000 nm or less. Thereby, the second sheet can simultaneously achieve good breathability and good waterproofness at a higher level. As a result of further research, the present inventor has found that the above effect is more reliably achieved when the degree of variation in the fiber diameter of the first fiber constituting the fiber aggregate is within a predetermined range where the degree of variation is large to some extent. rice field.

<Constitution>
Therefore, the third sheet is the above-mentioned second sheet, and the coefficient of variation in the quantity distribution of the fiber diameter of the first fiber constituting the fiber aggregate is 0.50 or more and 0.65 or less. It is a characteristic breathable tarpaulin. The "coefficient of variation" referred to here is an index indicating the magnitude of variation in the quantity distribution of the fiber diameter of the first fiber, and as is well known to those skilled in the art, the standard deviation of the quantity distribution of the fiber diameter of the first fiber. Can be obtained by dividing by the average value of the fiber diameters of the first fibers.

FIG. 5 shows the fibers contained in the fiber aggregate constituting the breathable tarpaulin (third sheet) according to the third embodiment of the present invention and the non-woven fabric constituting the breathable tarpaulin (conventional sheet) according to the prior art. It is a schematic graph which shows the distribution of a fiber diameter. FIG. 5A shows the distribution of the fiber diameter of the first fiber having a central fiber diameter of 1500 nm illustrated in FIG. 3B, and the coefficient of variation is 0.59. On the other hand, FIG. 5 (b) shows the distribution of the fiber diameter of the fiber having a central fiber diameter of 20 μm contained in the nonwoven fabric constituting the conventional sheet exemplified in FIG. 4 (b), and the coefficient of variation is 0.18. be. As is clear from the comparison between (a) and (b) of FIG. 5, the coefficient of variation of the fiber diameter distribution in the fiber aggregate of the breathable waterproof sheet (sheet of the present invention) according to the present invention is the non-woven fabric of the conventional sheet. It is significantly larger than the coefficient of variation of the fiber diameter distribution in. As a result, the sheet of the present invention can more reliably achieve both good breathability and good waterproofness.

The above-mentioned "variation coefficient" is also the same as the above-mentioned "center fiber diameter" of the first fiber, and in the process of manufacturing the fiber aggregate, for example, the temperature and the discharge amount of the first liquid which is a liquid containing the first material. Further, the first material contained in the discharged first liquid can be changed by adjusting the production conditions such as the temperature and the flow velocity of the gas conveyed to the downstream side while stretching in a thread shape.

<effect>
As described above, in the third sheet, the coefficient of variation in the quantity distribution of the fiber diameter of the first fiber constituting the fiber aggregate is 0.50 or more and 0.65 or less. As a result, the third sheet can more reliably achieve both good breathability and good waterproofness.

<< Fourth Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “fourth sheet”) according to the fourth embodiment of the present invention will be described.

As described above, in the third sheet, the coefficient of variation in the quantity distribution of the fiber diameter of the first fiber constituting the fiber aggregate is 0.50 or more and 0.65 or less. As a result, the third sheet can more reliably achieve both good breathability and good waterproofness. As a result of further research, the present inventor has found that the above effect is more reliably achieved when the bulk density of the fiber aggregate is within a predetermined range.

<Constitution>
Therefore, the fourth sheet is the second sheet or the third sheet described above, and is characterized in that the bulk density of the fiber aggregate is 0.01 g / cm ³ or more and 0.10 g / cm ³ or less. It is a breathable waterproof sheet.

As is well known to those skilled in the art, "bulk density" is a value obtained by dividing the mass of an object by the apparent volume. The porosity, which has a strong correlation with the waterproofness of the fourth sheet, is affected by, for example, the quantity distribution of the fiber diameters of the first fibers constituting the fiber aggregate and the degree of entanglement between the first fibers, and is affected by the above-mentioned "bulk". It is roughly inversely proportional to "density". That is, a low bulk density indicates a high porosity, and a high bulk density indicates a low porosity. Although the properties are different from those of water repellency and waterproofness, it can be said that water repellency is a property that can contribute to waterproofness, and generally, the higher the water repellency, the higher the waterproofness.

When the bulk density of the fiber aggregate composed of the first fibers is 0.01 g / cm ³ or more, the fiber aggregate has high water repellency, so that, for example, water as a liquid comes into contact with the fiber aggregate. Even in such a case, it is difficult for water to permeate the inside of the fiber aggregate, and as a result, it is difficult for water to permeate the fiber aggregate. That is, when the bulk density of the fiber aggregate composed of the first fibers is 0.01 g / cm ³ or more, the fiber aggregate can exhibit good waterproofness.

On the other hand, as described above, the higher the bulk density of the fiber aggregate, the lower the porosity, and as a result, the air permeability of the fiber aggregate also decreases. Therefore, from the viewpoint of achieving both high waterproofness and high breathability, it is desirable to keep the bulk density of the fiber aggregate low as long as the required waterproofness is achieved. From this point of view, the bulk density of the fiber aggregate contained in the fourth sheet is 0.10 g / cm ³ or less.

<effect>
As described above, in the fourth sheet, the bulk density of the fiber aggregate is 0.01 g / cm ³ or more and 0.10 g / cm ³ or less. As a result, according to the fourth sheet, both good breathability and good waterproofness can be more reliably achieved. Preferably, the bulk density of the fiber aggregate contained in the fourth sheet is 0.02 g / cm ³ or more and 0.05 g / cm ³ or less. More preferably, the bulk density of the fiber aggregate contained in the fourth sheet is 0.04 g / cm ³ or more and 0.05 g / cm ³ or less.

<< Fifth Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “fifth sheet”) according to the fifth embodiment of the present invention will be described.

As described above, in the fourth sheet characterized by having a bulk density of 0.01 g / cm ³ or more and 0.10 g / cm ³ or less, the fiber aggregate has good air permeability and good waterproofing. It is possible to achieve both sex more reliably. In particular, with respect to water repellency, the fourth sheet exhibits a fourth to fifth grade wet state in the above-mentioned spray test.

<Constitution>
Therefore, the fifth sheet is the fourth sheet described above, and is characterized in that the fiber aggregate exhibits a fifth to fourth grade wet state in a water repellency test according to JIS L 1092: 2009. It is a breathable tarpaulin.

The water repellency test based on JIS L 1092: 2009 is also called "spray test", and 250 mL of water is applied to the test piece fixed to the holding frame from a predetermined nozzle for a period of 25 to 30 seconds. It is a test method to evaluate by the grades listed below according to the wet state of the test piece after spraying.

Grade 1: The one that shows wetness on the entire surface.
Grade 2: Wetness is shown on half of the surface, and small individual wettings permeate the cloth.
Grade 3: Shows small individual water droplet-like wetness on the surface.
Grade 4: Those that do not get wet on the surface but show the adhesion of small water droplets.
Grade 5: No wetness or water droplets on the surface.

Table 1 below shows the differences in water repellency when the bulk density of the fiber aggregate having a thickness of 2 mm and the central fiber diameter of the first fiber constituting the fiber aggregate are variously changed. The water repellency data shown in Table 1 show the wet state grade specified in the water repellency test according to JIS L 1092: 2009 described above. In Table 1, for comparison, the water repellency of the non-woven fabric of the conventional sheet made of fibers having a central fiber diameter of 20 μm (= 20000 nm) as described above is also described.

As shown in Table 1, the wet state grade in the above-mentioned spray test varies depending on the combination of the central fiber diameter, which is the most frequent value in the quantity distribution of the fiber diameters constituting the fiber aggregate, and the bulk density of the fiber aggregate. do. In other words, in the fifth sheet, the wet state grade in the spray test can be graded 4 to 5 by appropriately selecting the combination of the central fiber diameter and the bulk density in the fiber aggregate. .. Since the fiber aggregate has high water repellency, it is difficult for water to permeate into the inside of the fiber aggregate even when water as a liquid is in contact with the fiber aggregate, and as a result, the fiber aggregate is not likely to permeate. Water does not easily permeate through the fiber aggregate, and good waterproofness can be exhibited.

On the other hand, the non-woven fabric of the conventional sheet made of fibers having a central fiber diameter of 20 μm has a high bulk density of 0.07 g / cm ³ , but the wet state grade in the above-mentioned spray test is second grade. It has become. That is, the non-woven fabric has poor water repellency, and the conventional sheet containing the non-woven fabric cannot exhibit sufficient waterproofness.

As described above, in the above-mentioned spray test, the wet state of the non-woven fabric constituting the conventional sheet is grade 2, whereas the wet state of the fiber aggregate constituting the fifth sheet is

grade

4 or 5. That is, the fiber aggregate constituting the fifth sheet has extremely high water repellency as compared with the non-woven fabric constituting the conventional sheet.

<effect>
Since the fiber aggregate constituting the fifth sheet has high water repellency, water into the inside of the fiber aggregate constituting the fifth sheet even when the fifth sheet is in contact with water as a liquid, for example. It is difficult for water to permeate through the fifth sheet as a result. That is, according to the fifth sheet, even when the water is in contact with water as a liquid, the possibility that the water permeates the fifth sheet is low, and good waterproofness can be exhibited.

<< 6th Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “sixth sheet”) according to the sixth embodiment of the present invention will be described.

The fiber aggregates constituting the breathable waterproof sheet (sheet of the present invention) according to the present invention, including the first to fifth sheets described above, have a fine fiber diameter that is irregularly entangled with each other. It is an aggregate made of fibers and can achieve good breathability and good waterproofness at the same time. Further, in the above-mentioned 4th sheet and 5th sheet, attention is paid to water repellency as one of the properties that can contribute to waterproofness, and the fiber aggregate has a bulk density in a suitable range in which the desired water repellency can be achieved. Has. As a result, according to the 4th sheet and the 5th sheet, even when the fiber is in contact with water as a liquid, it is difficult for water to permeate into the fiber aggregate, and good waterproofness is exhibited. Can be done.

However, depending on the application to which the sheet of the present invention is applied, for example, it is assumed that water as a liquid is not only in contact with the fiber aggregate constituting the sheet of the present invention but also a certain amount of water pressure is applied. To. Needless to say, it is desirable that the breathable waterproof sheet can exhibit good waterproofness and good breathability even in such a situation where a certain amount of water pressure is applied to the fiber aggregate.

Therefore, the present inventor has a breathability from the side of the sheet of the present invention that is not in contact with water to the side that is in contact with water in a situation where a predetermined water pressure is applied to the sheet of the present invention (hereinafter, "waterproof breathability"). A test was conducted to quantitatively evaluate). The contents of the test will be described in detail below.

<Waterproof breathability evaluation test>
FIG. 6 is a schematic perspective view showing an example of the configuration of the test device for evaluating the waterproof air permeability described above. The test device 100 illustrated in FIG. 6 includes a lower chamber 110 and an upper chamber 120. The lower chamber 110 is a container having a bottomed cylindrical shape, and an introduction pipe 111 for introducing air into the inside of the lower chamber 110 from a high-precision dispenser for pressurization (not shown) is provided on the side surface. On the other hand, the chamber 120 is a container having a cylindrical shape, and the upper end thereof is open. The inner diameters of the lower chamber 110 and the upper chamber 120 are both 60 mm, and the height of the upper chamber 120 is 135 mm (that is, the internal volume of the upper chamber 120 is about 380 cm ³ ).

Flange portions (not shown) are formed at the upper end portion of the lower chamber 110 and the lower end portion of the upper chamber 120, respectively, and while sandwiching the fiber aggregate as the test piece 130 between the flange portions of both, the lower chamber 110 It is configured so that the upper end portion and the lower end portion of the upper chamber 120 can be connected via the test piece 130. After fixing the lower chamber 110, the upper chamber 120, and the test piece 130 in this way, 200 cm ³ of water 140 is injected into the upper chamber. As described above, since the inner diameter of the upper chamber 120 is 60 mm, the height of the injected water 140 is about 7.1 cm (= 200 cm ³ / (3 cm × 3 cm × π)). That is, the water pressure applied to the fiber aggregate as the test piece 130 is about 694 Pa (= about 71 mmH ₂ O).

In the above state, air is introduced from the high-precision dispenser into the inside of the lower chamber 110 through the introduction pipe 111 of the lower chamber 110. The pressure difference between the pressure of the lower chamber 110 and the ambient pressure (atmospheric pressure) when bubbles start to be generated from the surface of the test piece 130 in the water 140 contained in the upper chamber 120 is recorded as an index of waterproof air permeability. .. The smaller the pressure difference (hereinafter, sometimes referred to as "ventilation start pressure"), the higher the waterproof air permeability (good), and the larger the pressure difference, the lower the waterproof air permeability (hereinafter, the better). Not good). In FIG. 6, the air flow after the bubbles start to be generated from the surface of the test piece 130 in the water 140 is represented by the white arrows.

<Waterproof breathability evaluation result>
FIG. 7 shows the thickness of the test piece 130 and the above-mentioned aeration start pressure, which are the thickness of the test piece 130 and the fiber aggregate having a bulk density of 0.05 g / cm ³ and consisting of the first fiber having a central fiber diameter of 800 nm, 1500 nm, 2000 nm and 4500 nm. It is a graph which shows the relationship with. As shown in FIG. 7, it can be seen that the aeration start pressure has a positive correlation with the thickness of the test piece, and the two are in a substantially proportional relationship. Further, the test piece having a central fiber diameter of 800 nm and a thickness of 40 mm (consisting of the fiber aggregate constituting the fourth sheet described above) also exhibited a low aeration starting pressure of 3700 Pa, so that the sheet of the present invention is good. It can be seen that it has excellent breathability.

FIG. 8 is a graph showing the relationship between the bulk density and the aeration starting pressure of the test piece 130 made of the first fiber having the central fiber diameters of 800 nm, 1500 nm, 2000 nm and 4500 nm and made of the fiber aggregate having the thickness of 5 mm. Is. Further, FIG. 9 shows 0.02 to 0. In the test piece 130 made of a first fiber having a central fiber diameter of 1500 nm and a fiber aggregate having a thickness of 5 mm (constituting the fourth sheet described above). It is a graph which shows the relationship between the bulk density of 05 g / cm ³ and the aeration start pressure. As shown in FIGS. 8 and 9, the aeration start pressure has a positive correlation with the bulk density of the test piece, and the higher the bulk density, the larger the aeration start pressure (that is, the air permeability is the bulk of the test piece). It has a negative correlation with density, and the higher the bulk density, the lower the air permeability). However, since the thickness of the fiber aggregate is 5 mm in the first place, it can be seen that the aeration starting pressure is sufficiently low at about 400 Pa even at a bulk density of 0.05 g / cm ³ . The numerical values shown in parentheses in the graph of FIG. 8 indicate the grade of water repellency in the above-mentioned spray test, and it can be seen that the higher the bulk density of the fiber aggregate, the higher the water repellency.

In the fiber aggregate having a bulk density of less than 0.01 g / cm ³ , water leakage occurred when 200 cm ³ of water was injected into the upper chamber 120, and the waterproof air permeability could not be evaluated. That is, it was found that under the above test conditions, the waterproof property of the breathable waterproof sheet containing the fiber aggregate having a bulk density of less than 0.01 g / cm ³ was insufficient. From this point of view, it is desirable that the bulk density of the fiber aggregate constituting the sheet of the present invention is 0.01 g / cm ³ or more.

<Constitution>
From the above, the sixth sheet is any of the breathable waterproof sheets (sheets of the present invention) according to various embodiments of the present invention, including the above-mentioned first to fifth sheets, and is evaluated for waterproof breathability. It is a breathable waterproof sheet characterized in that the ventilation start pressure measured by the test is 400 Pa or less. As described above, the waterproof breathability evaluation test is a process of increasing the air pressure applied to the other side of the breathable waterproof sheet in a state where a water pressure of 71 _mmH2O is applied to one side of the breathable waterproof sheet. It is a test to measure the pressure difference on both sides of the breathable waterproof sheet when air bubbles start to be generated on the side of. The ventilation start pressure refers to the above-mentioned atmospheric pressure difference measured in the waterproof air permeability evaluation test.

As is clear from the results exemplified in FIGS. 7 to 9, the aeration start pressure measured by the above-mentioned waterproof air permeability evaluation test is the center which is the most frequent value in the quantity distribution of the fiber diameters constituting the fiber aggregate. It varies depending on the combination of the fiber diameter, the bulk density of the fiber aggregate, and the thickness of the fiber aggregate. In other words, in the sixth sheet, the ventilation start pressure measured by the waterproof air permeability evaluation test is set to a desired value (for example, by appropriately selecting the combination of the central fiber diameter, the bulk density and the thickness in the fiber aggregate. , 400 Pa or less).

<effect>
As described above, the fiber aggregate constituting the sixth sheet exhibits a ventilation starting pressure of 400 Pa or less in the waterproof breathability evaluation test described above. That is, according to the sixth sheet, even when a predetermined water pressure is applied to the fiber aggregate, it is possible to exhibit good air permeability while exhibiting good waterproof property.

As described with reference to FIG. 7, in the breathable waterproof sheet (sheet of the present invention) according to the present invention, the breathability decreases as the thickness of the fiber aggregate increases. On the other hand, the larger the thickness of the fiber aggregate, the higher the waterproof property. Further, in general, the thicker the fiber aggregate is, the more it is evaluated by, for example, a water resistance test based on JIS L 1092: 2009 A method (low water pressure method) and B method (high water pressure method). Increases water resistance. Further, the mechanical strength of the sheet of the present invention (for example, breaking strength, etc.) also increases as the thickness of the fiber aggregate increases. In addition, these properties such as breathability, waterproofness, water resistance and mechanical strength are also influenced by the bulk density of the fiber aggregate. Therefore, depending on the performance as a breathable waterproof sheet required in the application in which the sheet of the present invention is used, the fiber diameter and distribution thereof of the first fiber constituting the fiber aggregate and the bulk density and thickness of the fiber aggregate are determined. It will be adjusted accordingly.

For example, in applications where high water pressure resistance and / or mechanical strength is required, the thickness of the fiber aggregate constituting the sheet of the present invention is increased, for example, in a range that does not impair the performance required for the breathable waterproof sheet. The water pressure resistance of the fiber aggregate itself may be increased. Alternatively, for example, a reinforcing layer (support layer) having at least breathability may be laminated on the fiber aggregate of the sheet of the present invention to increase the water pressure resistance of the sheet of the present invention as a whole.

<< 7th Embodiment >>
Hereinafter, the breathable waterproof sheet (hereinafter, may be referred to as “7th sheet”) according to the 7th embodiment of the present invention will be described.

As described above, the fiber aggregate constituting the breathable waterproof sheet (sheet of the present invention) according to the present invention is an aggregate composed of fine first fibers that are irregularly entangled with each other, thereby providing good breathability and good breathability. Good waterproofness can be achieved at the same time. Needless to say, in the application in which such a sheet of the present invention is used, it is not desirable that the first fiber loosened from the fiber aggregate falls off and leaks to the surroundings.

<Constitution>
Therefore, the 7th sheet is any of the breathable waterproof sheets (sheets of the present invention) according to various embodiments of the present invention, including the 1st to 6th sheets described above, and gas can pass therethrough. A breathable waterproof sheet further comprising a cover sheet which is a sheet-like member having a plurality of gaps, and at least a part of the fiber aggregate is covered with the cover sheet so that the first fiber does not leak. Is.

The material constituting the cover sheet is not particularly limited as long as it can withstand the usage environment and usage conditions as a breathable waterproof sheet. Specific examples of such materials include resins such as polyolefins, polyesters, polyamides and various fluororesins. In this case, the material constituting the cover sheet may be the same as or different from the first material described above. Alternatively, the material constituting the cover sheet may be a metal such as stainless steel.

Further, in the 7th sheet, at least a part of the fiber aggregate is covered with a cover sheet so that the 1st fiber does not leak. That is, even if a part of the first fiber constituting the fiber aggregate is unraveled, the entire fiber aggregate is covered with the cover sheet as long as the unraveled first fiber does not leak to the outside of the cover sheet. Alternatively, a part of the fiber aggregate may be covered with a cover sheet. In the former case, for example, the fiber aggregate may be housed inside the bag-shaped cover sheet, and the entire fiber aggregate may be covered with the cover sheet by closing the opening of the bag-shaped cover sheet. can. On the other hand, in the latter case, for example, the fiber aggregate is sandwiched between the pair of cover sheets, and the pair of cover sheets are adhered to each other at least partially via the fiber aggregate to form a part of the fiber aggregate. It can be covered with a cover sheet.

The form of the cover sheet is not particularly limited as long as it is a sheet-like member having a plurality of gaps through which gas can pass. Specific examples of the form of the cover sheet include a porous sheet, a mesh, a non-woven fabric, and a woven fabric. Preferably, the cover sheet is a non-woven fabric or mesh made of fibers made of the above-mentioned materials.

<effect>
As described above, the seventh sheet is a ventilated sheet including a fiber aggregate composed of irregularly entangled fine first fibers and a cover sheet which is a sheet-like member having a plurality of gaps through which a gas can pass. It is a sex tarpaulin. Further, in the 7th sheet, at least a part of the fiber aggregate is covered with a cover sheet so that the 1st fiber does not leak. As a result, according to the seventh sheet, even when the first fiber is unraveled from the fiber aggregate, the possibility that the first fiber leaks to the surroundings can be reduced.

As described above, for the purpose of explaining the present invention, some embodiments having a specific configuration have been described with reference to the accompanying drawings at times, but the scope of the present invention is limited to these exemplary embodiments. It should not be construed as being limited, and it goes without saying that amendments can be made as appropriate within the scope of the claims and the matters described in the specification.

100 ... test equipment, 110 ... lower chamber, 111 ... introduction pipe, 120 ... upper chamber, 130 ... test piece, and 140 ... water.

Claims

A breathable waterproof sheet comprising a fiber aggregate, which is an aggregate of the first fiber, which is a fiber having a fiber diameter of 300 nm or more and less than 5000 nm, which is made of a first material which is a lipophilic polymer material. There,
In the fiber aggregate, the first fibers are irregularly entangled with each other.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to claim 1,
The central fiber diameter, which is the mode in the quantity distribution of the fiber diameter of the first fiber, is 800 nm or more and 3000 nm or less.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to claim 2.
The coefficient of variation in the quantity distribution of the fiber diameter of the first fiber is 0.50 or more and 0.65 or less.
A breathable tarpaulin that features this.
In the breathable tarpaulin according to claim 2 or 3.
The bulk density of the fiber aggregate is 0.01 g / cm 3 or more and 0.10 g / cm 3 or less.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to claim 4,
In a water repellency test according to JIS L 1092: 2009, the fiber aggregate shows a fifth to fourth grade wet state.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to any one of claims 1 to 5.
The breathability when air bubbles start to be generated on one side in the process of increasing the air pressure applied to the other side of the breathable waterproof sheet in a state where a water pressure of 71 mmH2O is applied to one side of the breathable waterproof sheet. The ventilation start pressure measured by the waterproof breathability evaluation test, which is a test for measuring the pressure difference on both sides of the waterproof sheet as the ventilation start pressure, is 400 Pa or less.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to any one of claims 1 to 6.
The first material is polyolefin.
A breathable tarpaulin that features this.
In the breathable tarpaulin according to claim 7.
The first material is at least one polymer material selected from the group consisting of polyethylene, polypropylene and polybutylene.
A breathable tarpaulin that features this.
In the breathable waterproof sheet according to any one of claims 1 to 8.
It further includes a cover sheet, which is a sheet-like member having a plurality of gaps through which gas can pass.
At least a part of the fiber aggregate is covered with the cover sheet so that the first fiber does not leak.
A breathable tarpaulin that features this.
In the breathable tarpaulin according to claim 9.
The cover sheet is a non-woven fabric or a mesh.
A breathable tarpaulin that features this.