Functional sheet

Abstract

To provide a functional sheet having high air permeability while allowing a functional material to be less prone to detachment.SOLUTION: In a breathable functional sheet 100 in which a functional material layer 130 is sandwiched between a front-side base sheet 110 and a rear-side base sheet 120, the functional material layer 130 is configured to include powder-granular functional materials 131 and a filamentary adhesive 132 that connects the functional materials 131 to one another by being entangled with the functional material 131. Because the functional materials 131 are connected to one another by the filamentary adhesive 132, it becomes possible to make the functional materials 131 unlikely to fall off from the functional sheet 100 while maintaining high air permeability of the functional sheet 100.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a breathable functional sheet in which a powdery functional material is sandwiched between a front substrate sheet and a back substrate sheet. [Background technology]

[0002] An adsorption filter (functional sheet) for adsorbing and removing substances is formed by bonding powdered activated carbon (functional material) to a nonwoven fabric (base sheet). A known method for manufacturing this type of filter is the "sintering method." As shown in FIG. 7 , in the sintering method, a mixture of activated carbon 930 and a heat-melting adhesive 940 is spread over one nonwoven fabric 920, which is then heated in a heating furnace 99 to melt the adhesive 940. Then, another nonwoven fabric 910 is placed over the activated carbon 930 and the adhesive 940, and pressure rollers 91 and 92 are used to pressurize and integrate the nonwoven fabrics 910 and 920 (see, for example, paragraphs 0051 to 0053 and 0055 to 0063 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-069405 Summary of the Invention [Problem to be solved by the invention]

[0004] However, filters manufactured by the above-mentioned sintering method have a problem in that the activated carbon 930 tends to fall off from the nonwoven fabrics 910, 920, for example, when the filter is cut or pleated. Furthermore, it has been pointed out that increasing the amount of adhesive 940 in an attempt to solve these problems results in a problem of reduced breathability of the filter.

[0005] The present invention has been made to solve the above problems, and provides a functional sheet in which functional materials are less likely to fall off and which has high breathability. [Means for solving the problem]

[0006] The above issues are: A breathable functional sheet in which a functional material layer is sandwiched between a front substrate sheet and a back substrate sheet, The functional material layer is A granular functional material, A thread-like adhesive that connects functional materials together by being entangled in the functional materials. Equipped with A functional sheet characterized by This is solved by providing

[0007] In this functional sheet, as shown in Figures 1 and 2 below, the powder-like functional material 131 that forms the functional material layer 130 is connected to each other by entangled thread-like (mesh-like) adhesive 132. This makes it possible to make the functional material 131 less likely to fall off from the functional sheet 100 while maintaining high breathability of the functional sheet 100.

[0008] The terms "front" and "back" in "front-side substrate sheet" and "back-side substrate sheet" simply refer to the side that will be the upper side when manufacturing the functional sheet, which will be described in detail later, as "front" and the side that will be the lower side as "back." Therefore, these terms do not limit the orientation in which the functional sheet is used.

[0009] In the above-mentioned functional sheet, the functional material layer and the front-side substrate sheet, and the functional material layer and the back-side substrate sheet are preferably bonded together with a thread-like adhesive, which makes it easier to improve the breathability of the functional sheet.

[0010] In the functional sheet, it is preferable to keep the adhesive content low. Specifically, the adhesive content [g / m 2] is the amount of functional material retained F [g / m 2 This makes it easier to improve the breathability of the functional sheet.

[0011] In the above functional sheet, the amount of functional material retained F is set to 50 [g / m 2 That is, the amount of functional material retained per unit area can be increased, and the functionality of the functional sheet can be further improved.

[0012] Generally, increasing the amount of functional material retained tends to decrease the breathability of the functional sheet. However, in the above-mentioned functional sheet, by using a thread-like adhesive, the amount of functional material retained F can be increased to 50 [g / m 2 Even when the air flow rate is increased to 5.3 [cm / s] or more, the air permeability of the functional sheet can be maintained at a high level (i.e., the pressure loss can be kept small). Specifically, when the surface air velocity is 5.3 [cm / s] and the measurement area is 100 [cm 2 ], the pressure loss D [Pa] measured under the condition of 2 ] is 0.28 [km / s 2 ] can be made to be as follows.

[0013] In addition, in the above functional sheet, the amount of functional material retained F is [100 g / m 2 Even if the amount of the functional material is increased to 300 mg or more, the functional material is less likely to fall off from the functional sheet. Specifically, the amount of functional material that falls off when cut, as measured in the following steps 1 to 4, can be kept to 300 mg or less. Step 1: Take a 300mm square test piece from the functional sheet Step 2: Using a rotary cutter, make 10 cuts in each test piece that are roughly parallel to one side of the test piece and cross the test piece. Step 3: After cutting, gently shake the test piece while lifting it up, and collect and weigh any functional materials that have fallen off the test piece. Step 4: Repeat steps 1 to 3 three times, calculate the average weight [mg] of the functional material that fell off, and use this average as the amount of functional material that fell off during cutting.

[0014] In the above-mentioned functional sheet, it is preferable to use sheet materials having an elongation of 20% or more as the front-side substrate sheet and the back-side substrate sheet as measured in accordance with JIS L1913 (2010), which makes it possible to make the back-side substrate sheet and the front-side substrate sheet less susceptible to breakage when the functional sheet is pleated.

[0015] In the above-mentioned functional sheet, it is preferable to use, as the front-side substrate sheet and the back-side substrate sheet, sheet materials having a stiffness of 6 [mN] or less as measured by the Gurley method in accordance with JIS L1913 (2010). This makes it possible to prevent cracks and breaks from occurring in the functional material layer when the functional sheet is pleated. [Effects of the Invention]

[0016] As described above, the present invention makes it possible to provide a functional sheet in which the functional material is less likely to fall off and which has high breathability. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view schematically showing a functional sheet of the present embodiment cut along a plane parallel to the thickness direction. [Figure 2] 1 is a photograph showing the functional material layer exposed after peeling off the front-side base sheet 110 from the functional sheet of this embodiment. [Figure 3] 1 is a diagram schematically illustrating a state in which a functional sheet manufacturing apparatus according to an embodiment of the present invention is viewed from the side. [Figure 4] 4 is an enlarged perspective view showing the vicinity of the bottom of a functional material adhesive discharge means in the manufacturing apparatus shown in FIG. 3. FIG. [Figure 5]1 is a graph showing the relationship between D / F [km / s2] and the amount of functional material retained F [g / m2] obtained in Experiment 1. [Figure 6] Photographs showing the results of Experiment 2. [Figure 7] FIG. 1 is a diagram showing a schematic side view of a conventional (sinter method) functional sheet manufacturing apparatus. [Figure 8] 1 is a photograph showing the state in which the front-side base material sheet 110 has been peeled off from a conventional (sinter method) functional sheet, exposing the functional material layer. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. Overview A preferred embodiment of the present invention will be described in more detail with reference to the drawings. Fig. 1 is a cross-sectional view showing a functional sheet 100 of this embodiment cut along a plane parallel to the thickness direction. Fig. 2 is a photograph showing the functional sheet 100 of this embodiment with the front-side substrate sheet 110 peeled off to expose the functional material layer 130.

[0019] As shown in FIG. 1, the functional sheet 100 of this embodiment has a structure in which a functional material layer 130 is sandwiched between a pair of front and back substrate sheets (a front-side substrate sheet 110 and a back-side substrate sheet 120). Both the back-side substrate sheet 120 and the front-side substrate sheet 110 are breathable sheet-like members (breathable sheets). The functional material layer 130 comprises a powdery functional material 131 and a thread-like adhesive (a functional material adhesive 132) randomly entangled with the functional material 131. The powdery functional material 131 is connected to itself by the functional material adhesive 132, as shown in FIG. 2. This makes it difficult for the functional material 131 to fall off from the functional sheet 100 and improves the breathability of the functional sheet 100.

[0020] In the functional sheet 100 of this embodiment, as shown in FIG. 1, the functional material layer 130 and the front-side base sheet 110 are bonded together with a thread-like adhesive (front-side adhesive 111), and the functional material layer 130 and the back-side base sheet 120 are bonded together with a thread-like adhesive (back-side adhesive 121). This further improves the breathability of the functional sheet 100. In this embodiment, synthetic rubber-based hot melt adhesives are used as the functional material adhesive 132, the front-side adhesive 111, and the back-side adhesive 121. As long as the front-side adhesive 111 is thread-like, its arrangement pattern is not limited, and it can be, for example, striped or lattice-like. In this embodiment, as shown in FIG. 2, like the functional material adhesive 132, the front-side adhesive 111 also has a randomly tangled mesh-like pattern. The back-side adhesive 121 can also have a similar structure to the front-side adhesive 111.

[0021] The functional sheet 100 is not limited in its use. The use of the functional sheet 100 can be changed by changing the type of functional material 131 used. For example, if the functional material 131 is a substance having a deodorizing function, such as activated carbon, the functional sheet 100 can be used as a deodorizing filter. If the functional material 131 is a substance having a water absorbing function, such as silica gel or zeolite, the functional sheet 100 can be used as a moisture absorbing filter. For convenience of explanation, the following description will be given taking as an example a case where powdered or granular activated carbon is used as the functional material 131 and a deodorizing filter is manufactured as the functional sheet 100.

[0022] 2. Manufacturing method of functional sheets The manufacturing apparatus and manufacturing method for the functional sheet 100 of this embodiment will be described in detail below. Fig. 3 is a diagram schematically showing the state of the manufacturing apparatus for the functional sheet 100 of this embodiment as seen from the side. Fig. 4 is a perspective view showing an enlarged view of the vicinity of the bottom of the functional material adhesive discharge means 40 in the manufacturing apparatus shown in Fig. 3.

[0023] The device shown in Figure 3 comprises a base sheet transport means 10, a functional material hopper 20, a functional material dispersion means 30, a functional material adhesive discharge means 40, a functional material slider 50, a back-side adhesive discharge means 60, a front-side adhesive discharge means 70, an integration base sheet feed means 80, and a press means 90.

[0024] In the apparatus shown in FIG. 3 , a functional material adhesive 132 is discharged in thread form by a functional material adhesive discharge means 40 onto the functional material 131 (the functional material 131 in the air) as it falls from a functional material hopper 20 toward the back-side base sheet 120. Therefore, even though the functional material 131 and the functional material adhesive 132 are dropped separately, when they fall onto the top surface of the back-side base sheet 120, the powder-like functional material 131 is connected to each other by the thread-like functional material adhesive 132. This makes it possible to prevent the functional material 131 from falling off the base sheets 110 and 120. This effect is particularly useful when the amount of functional material 131 (activated carbon) is increased. Furthermore, by reducing the amount of adhesive used, it is possible to prevent the adhesive from blocking the voids (ventilation spaces) in the base sheets 110 and 120 and the gaps between the functional material 131. This also improves the breathability of the resulting functional sheet 100. These make it possible to improve the performance (deodorizing performance and breathability) of the resulting functional sheet 100 (deodorizing filter).

[0025] In the device shown in FIG. 3 , before dropping the functional material 131 onto the back-side substrate sheet 120, the back-side adhesive 121 is dispensed in thread form onto the back-side substrate sheet 120 by the back-side adhesive dispensing means 60. Next, the functional material 131 is dropped onto the back-side substrate sheet 120, and then the front-side adhesive 111 is dispensed in thread form onto the functional material 131 (functional material layer 130) on the back-side substrate sheet 120 by the front-side adhesive dispensing means 70, and the front-side substrate sheet 110 is then placed on top of it. This allows the functional material 131 to be firmly bonded to both the back-side substrate sheet 120 and the front-side substrate sheet 110, thereby increasing the peel strength between the back-side substrate sheet 120 and the front-side substrate sheet 110. Additionally, the amount of adhesive used can be reduced, improving the breathability of the functional sheet 100. Furthermore, the back-side base material sheet 120 and the front-side base material sheet 110 can be firmly bonded together without applying strong pressure to them with the press means 90. This makes it possible to make the resulting functional sheet 100 flexible.

[0026] Each part of the device shown in FIG. 3 will now be described in detail.

[0027] 2.1 Base Sheet Transfer Means The base sheet transfer means 10 is for transferring the back-side base sheet 120. The mechanism of the base sheet transfer means 10 is not particularly limited. In this embodiment, the base sheet transfer means 10 is composed of a payout roller 11 and a take-up roller 12. A rotation drive means (such as an electric motor) (not shown) is attached to the take-up roller 12, and when this rotation drive means is driven, the take-up roller 12 is rotated. When the take-up roller 12 rotates, the back-side base sheet 120 is taken up by the take-up roller 12. Conversely, the back-side base sheet 120 wound around the pay-out roller 11 is pulled and paid out. In this way, the back-side base sheet 120 is transferred from the pay-out roller 11 toward the take-up roller 12. The transfer direction of the back-side base sheet 120 by the base sheet transfer means 10 is not particularly limited as long as it is a non-vertical direction. In this embodiment, the back-side base sheet 120 is transported in the horizontal direction, but it may also be transported in a direction inclined relative to the horizontal direction.

[0028] 2.2 Functional material hopper The functional material hopper 20 is a tank-shaped member that stores the functional material 131, and is capable of discharging the functional material 131 from a discharge port provided at the bottom of the functional material hopper 20. A discharge roller 21 is provided at the discharge port of the functional material hopper 20 to prevent a large amount of the functional material 131 from being discharged at once. The rotation of the discharge roller 21 allows the functional material 131 to be discharged at a substantially constant flow rate. The functional material 131 discharged from the functional material hopper 20 falls by gravity and is scattered on the upper surface of the back-side substrate sheet 120. A suction means (not shown) is provided below the back-side substrate sheet 120, so that the falling functional material 131 is attracted to the upper surface of the back-side substrate sheet 120. This prevents the functional material 131 from scattering around the back-side substrate sheet 120.

[0029] 2.3 Functional material dispersion means The functional material dispersing means 30 sieves and disperses the functional material 131 that has fallen from the functional material hopper 20. This allows the functional material 131 to fall substantially uniformly onto the upper surface of the back-side substrate sheet 120. The mechanism of the functional material dispersing means 30 is not particularly limited. In this embodiment, the functional material dispersing means 30 horizontally vibrates a punched metal with many small holes. The functional material 131 passes through the small holes while being shaken. Because the functional material 131 is in powder or granular form, it may fall into the functional material dispersing means 30 in a state where multiple particles are clumped together due to moisture, static electricity, etc. However, by passing the functional material 131 through the functional material dispersing means 30, the functional material 131 can be dispersed into individual particles.

[0030] 2.4 Functional material adhesive dispensing means The functional material adhesive dispensing means 40 is configured to dispense the functional material adhesive 132 in a thread-like (linear) form onto the functional material 131 as it falls toward the upper surface of the backside substrate sheet 120. This allows the functional material adhesive 132 to become entangled with the falling functional material 131, thereby connecting the powder-like functional materials 131 together. The mechanism of the functional material adhesive dispensing means 40 is not particularly limited as long as it can dispense the functional material adhesive 132. In this embodiment, the synthetic rubber-based hot melt adhesive used as the functional material adhesive 132 is initially in pellet or block form. This is melted into a liquid form using an applicator (not shown) and then supplied to the functional material adhesive dispensing means 40, from which the functional material adhesive 132 is dispensed by a curtain spray method. This eliminates the need to heat the adhesive 940 in a heating furnace 99 installed immediately before the pressure rollers 91 and 92, as in the filter manufacturing apparatus (sintering method) shown in FIG. 7 .

[0031] FIG. 4 shows an enlarged perspective view of the bottom of the functional material adhesive dispensing means 40. As shown in FIG. 4, the functional material adhesive dispensing means 40 is a tank-shaped member 42 with a number of adhesive dispensing ports 41 arranged at its bottom. The tank-shaped member 42 stores a functional material adhesive 132 (a liquid-melted functional material adhesive 132). An air pump or other tank pressurizing means (not shown) applies pressure from above the functional material adhesive 132 stored inside the tank-shaped member 42, causing the functional material adhesive 132 to be dispensed from the adhesive dispensing ports 41. Air outlets 43 are provided on both sides of each adhesive dispensing port 41. By discharging air from these air outlets 43, the functional material adhesive 132 dispensed from the adhesive dispensing ports 41 can be shaken and dispersed. This allows the functional material adhesive 132 to be dispensed uniformly onto the functional material 131 at the dispensing location α.

[0032] 2.5 Functional Material Slider The functional material slider 50 guides the functional material 131 that has passed through the functional material dispersion means 30 to a location α where the adhesive is discharged by the functional material adhesive discharge means 40. In this embodiment, the functional material slider 50 is configured as an inclined plate that is inclined relative to the horizontal. This allows the functional material 131 that has fallen from the functional material dispersion means 30 to be received on the upper surface of the inclined plate (functional material slider 50) and guided to the discharge location α by sliding along the upper surface of the inclined plate. The functional material 131 has a width W1 immediately after falling from the functional material dispersion means 30. By providing the functional material slider 50, the width W2 of the functional material 131 at the discharge location α can be made smaller than the width W1. If the width W2 of the functional material adhesive 132 at the discharge location α is wide, there will likely be differences in how the functional material adhesive 132 adheres to the functional material 131 between one side (the side closer to the functional material adhesive discharge means 40) and the other side (the side farther from the functional material adhesive discharge means 40) in a direction parallel to the width W2, but the functional material slider 50 can narrow the width W2.

[0033] Furthermore, if the functional material 131 is allowed to fall vertically from the functional material hopper 20 to the upper surface of the back-side substrate sheet 120 without providing the functional material slider 50, it becomes necessary to make the discharge direction of the functional material adhesive 132 by the functional material adhesive discharge means 40 a non-vertical direction, making it difficult to control the discharge state of the functional material adhesive 132. In this regard, by providing the functional material slider 50 and tilting the falling direction of the functional material 131 relative to the vertical direction as described above, it is possible to make the discharge direction of the functional material adhesive 132 by the functional material adhesive discharge means 40 a vertical direction.

[0034] The inclination angle θ (FIG. 3) of the functional material slider 50 relative to the horizontal direction is not particularly limited. However, if the inclination angle θ is too small, the functional material 131 will have difficulty sliding down the upper surface of the functional material slider 50. For this reason, the inclination angle θ is preferably 30° or more, and more preferably 40° or more. However, if the inclination angle θ is too large, it will be difficult to eject the functional material adhesive 132 in the vertical direction. For this reason, the inclination angle θ is preferably 80° or less, and more preferably 70° or less. In this embodiment, the inclination angle θ of the functional material slider 50 is set to approximately 45°. This allows the ejection direction of the functional material adhesive 132 to be approximately vertical.

[0035] 2.6 Backside adhesive dispensing means The back-side adhesive dispensing means 60 is configured to pre-dispense thread-like back-side adhesive 121 onto the upper surface of the back-side base sheet 120 before the functional material 131 is dropped. This allows the functional material 131 (functional material layer 130) to be more firmly bonded to the back-side base sheet 120. However, in the device shown in FIG. 3 , the functional material adhesive 132 is adhered to the functional material 131 by the functional material adhesive dispensing means 40, so the amount of back-side adhesive 121 dispensed by the back-side adhesive dispensing means 60 can be reduced. This makes it less likely that the back-side adhesive 121 will clog the gaps (ventilation spaces) in the back-side base sheet 120. The mechanism of the back-side adhesive dispensing means 60 is not particularly limited. In this embodiment, the same mechanism as the functional material adhesive dispensing means 40 described above is also employed for the back-side adhesive dispensing means 60. The discharge direction of the rear adhesive discharge means 60 is also vertical, similar to the functional material adhesive discharge means 40 .

[0036] 2.7 Front adhesive dispensing means The front-side adhesive dispensing means 70 is configured to dispense thread-like front-side adhesive 111 onto the upper surface of the functional material 131 (functional material layer 130) after it has been dropped onto the back-side base sheet 120. This allows the front-side base sheet 110 to be more firmly bonded to the functional material layer 130. However, in the device shown in FIG. 3 , the functional material adhesive 132 is adhered to the functional material 131 by the functional material adhesive dispensing means 40, so the amount of front-side adhesive 111 dispensed by the front-side adhesive dispensing means 70 can be reduced. This makes it less likely that the front-side adhesive 111 will clog the voids (ventilation spaces) in the front-side base sheet 110. The mechanism of the front-side adhesive dispensing means 70 is not particularly limited. In this embodiment, the same mechanism as the functional material adhesive dispensing means 40 described above is also employed for the front-side adhesive dispensing means 70. The discharge direction of the front side adhesive discharge means 70 is also vertical, similar to the functional material adhesive discharge means 40 .

[0037] 2.8 Integration base sheet feeding means The integrating substrate sheet feeding means 80 is used to feed the front-side substrate sheet 110 so that it overlaps the top surface of the functional material layer 130 after the front-side adhesive 111 has been discharged by the front-side adhesive discharging means 70. Together with a press means 90 (described later), this integrating substrate sheet feeding means 80 constitutes a "substrate sheet integrating means" that overlaps and integrates the front-side substrate sheet 110 with the back-side substrate sheet 120 and the functional material layer 130. The mechanism of the integrating substrate sheet feeding means 80 is not particularly limited. In this embodiment, as shown in FIG. 3 , the front-side substrate sheet 110 wound around a feed roller 81 is wound up together with the back-side substrate sheet 120 by a take-up roller 12, whereby the front-side substrate sheet 110 is fed from the feed roller 81 and overlapped on top of the functional material layer 130.

[0038] 2.9 Pressing Method The press means 90 is used to apply pressure to the overlapping back-side base material sheet 120 and front-side base material sheet 110. In this embodiment, as shown in Fig. 3, the press means 90 is composed of a pair of upper and lower pressure rollers 91, 92. The press means 90 applies pressure to the back-side base material sheet 120 and front-side base material sheet 110 by passing the back-side base material sheet 120 and front-side base material sheet 110, each containing a functional material 131, a functional material adhesive 132, a back-side adhesive 121, and a front-side adhesive 111, through the gap between the pressure rollers 91, 92, thereby bonding the back-side base material sheet 120 and the functional material 131 (functional material layer 130) and the front-side base material sheet 110 and the functional material 131 (functional material layer 130). The front-side base material sheet 110 fed from the feed roller 81 is wrapped around the upper pressure roller 91. This applies tension to the front-side base material sheet 110, allowing the front-side base material sheets 110 to be neatly stacked and integrated without wrinkles or the like.

[0039] As already mentioned, in the apparatus shown in FIG. 3 , the back-side adhesive 121 is attached to the back side (lower side) of the functional material layer 130, and the front-side adhesive 111 is attached to the front side (upper side) of the functional material layer 130. This allows for strong bonding between the back-side substrate sheet 120 and the functional material 131 (functional material layer 130), and between the front-side substrate sheet 110 and the functional material 131 (functional material layer 130), without the need for strong pressure. Therefore, the apparatus shown in FIG. 3 allows for a wider gap between the pressure rollers than conventional apparatuses. This prevents the resulting functional sheet 100 from becoming too hard (increasing the flexibility of the functional sheet 100). Furthermore, the breathability of the resulting functional sheet 100 can be adjusted by the applied pressure (the gap between the pressure rollers 91 and 92). The wider gap between the pressure rollers 91 and 92 can also further enhance the breathability of the functional sheet 100.

[0040] 3. Base sheet The type of the front-side substrate sheet 110 is determined appropriately depending on the application of the functional sheet 100, etc. When the functional sheet 100 is used as a filter such as a deodorizing filter, a nonwoven fabric is typically used as the front-side substrate sheet 110. Examples of nonwoven fabrics that can be used include those manufactured by a web obtained by a carding method, an airlaid method, a meltblown method, a spunbonding method, a flash spinning method, an electrospinning method, or the like, and then by a thermal bonding method such as a thermal bonding method, a binder bonding method such as a chemical bonding method, or a physical entanglement method such as a needle punching method or a hydroentanglement method. The material of the nonwoven fabric is not particularly limited, and can be polyester, vinylon, rayon, acrylic, nylon, polyolefin, etc., or a combination thereof. The type of the back-side substrate sheet 120 can be the same as that described for the front-side substrate sheet 110. The type of the front-side substrate sheet 110 and the type of the back-side substrate sheet 120 may be the same or different.

[0041] The weight per area of ​​the nonwoven fabric used as the back-side substrate sheet 120 is usually 10 g / m2 More than 500g / m 2 The range is as follows: 10g / m 2 More than 200g / m 2 In this embodiment, as will be described later, the functional material 131 is sucked onto the upper surface of the back-side base sheet 120 by a suction means disposed below the back-side base sheet 120, so that the air permeability of the back-side base sheet 120 (a value measured by the Frazier method defined in JIS L 1913; the same applies hereinafter) is 100 cc / cm or less. 2 / s or more, and 150cc / cm 2 In this embodiment, the air permeability of the back-side base sheet 120 is set to about 200 cc / cm 2 The front-side base material sheet 110 may have the same structure as the back-side base material sheet 120.

[0042] Incidentally, the functional sheet 100 is often used as a filter material, and such filter material may be pleated (a process in which the functional sheet 100 is repeatedly folded into a sawtooth shape in a side view, thereby increasing the surface area per unit area of ​​the filter material and improving the adsorption performance of the filter material). In this regard, if the front-side base material sheet 110 and the back-side base material sheet 120 of the functional sheet 100 are formed from a material with poor flexibility, there is a risk that the functional material 131 (functional material layer 130) will be easily peeled off from the front-side base material sheet 110 and the back-side base material sheet 120 when the functional sheet 100 is pleated.

[0043] For this reason, the elongation percentage (elongation percentage measured in accordance with JIS L1913 (2010)) of the front-side base sheet 110 and the back-side base sheet 120 (base sheets 110, 120) is preferably 20% or more. This makes it possible to prevent the functional material 131 from peeling from the base sheets 110, 120 even when the functional sheet 100 is pleated. The elongation percentage of the base sheets 110, 120 is more preferably 25% or more, and even more preferably 30% or more. However, if the elongation percentage of the base sheets 110, 120 is too high, it may be difficult to increase the strength of the functional sheet 100. For this reason, the elongation percentage of the base sheets 110, 120 is preferably 80% or less, and more preferably 70% or less.

[0044] For the same reason, it is preferable to use a sheet material whose stiffness (stiffness measured by the Gurley method in accordance with JIS L1913 (2010)) of the base sheets 110, 120 is 6 [mN] or less. (When a nonwoven fabric is used as the base sheets 110, 120, the stiffness in the machine direction (MD) of the nonwoven fabric. The same applies below.) of the base sheets 110, 120 is more preferably 4 [mN] or less, and even more preferably 2 [mN] or less.

[0045] 4. Functional materials The functional material 131 is not limited to a specific type or composition as long as it is a powder or granular material that can exhibit the desired function. For example, a powder or granular porous material can be used as the functional material 131. Examples of porous materials include activated carbon, zeolite, silica gel (porous silicon dioxide), diatomaceous earth, activated alumina, activated clay, aluminum silicate, magnesium silicate, ion exchange resin, and porous clay minerals. The functional material 131 can be used alone or in combination of two or more types.

[0046] The function of the functional material 131 is not particularly limited. Examples of the function of the functional material 131 include an adsorption function (such as a deodorizing function or a moisture absorbing function), a filtering function, etc. The functional material 131 may have only one type of function, or two or more types of functions.

[0047] When the functional material 131 has an adsorption function (when the functional sheet 100 is used as an adsorption filter), the type of substance to be adsorbed by the functional material 131 (the adsorbed substance) is not limited. The functional material 131 can be, for example, one or more functional materials selected from the group consisting of a volatile organic compound (VOC) adsorbing functional material having a VOC adsorption function, an acid adsorbing functional material having an acid gas adsorption function, a base adsorbing functional material having a basic gas adsorption function, and a neutral adsorbing functional material having a neutral gas adsorption function. Examples of VOCs include isobutanol, ethyl acetate, methyl isobutyl ketone, toluene, styrene, and xylene. Examples of acidic gases include sulfur compounds (hydrogen sulfide, alkanethiols, etc.), nitrogen compounds, acetic acid, hydrogen chloride, propionic acid, butyric acid, and valeric acid. Examples of basic gases include ammonia and amine compounds. Examples of neutral gases include sulfur-based neutral gases (methyl sulfide, methyl disulfide, etc.), aldehydes, etc. In this case, the functional material 131 may have only one type of adsorbent substance, or two or more types of adsorbents.

[0048] When a granular porous body is used as the functional material 131, the granular porous body can be either untreated or treated with a chemical. By treating with a chemical, the adsorption characteristics of the porous body can be changed, thereby increasing the adsorption efficiency of a specific adsorbate. The specific method of chemical treatment is not limited. Examples of types of chemical treatment include attachment, impregnation, and support (supporting a chemical on a granular porous body).

[0049] For example, when an acidic gas is used as the adsorbed substance, examples of chemicals used in the chemical treatment include basic chemicals such as metal carbonates (e.g., alkali metal carbonates such as potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate) and metal hydroxides (e.g., sodium hydroxide and potassium hydroxide). When a basic gas is used as the adsorbed substance, examples of chemicals used in the chemical treatment include acidic chemicals such as phosphoric acid, citric acid, malic acid, tartaric acid, ascorbic acid, sulfuric acid, nitric acid, ferrous chloride, and ferrous sulfate. When an aldehyde gas is used as the adsorbed substance, examples of chemicals used in the chemical treatment include amine compounds (e.g., primary amine compounds such as acid hydrazide compounds, ethanolamine, polyethyleneimine, aniline, anisidine, and the like). The granular porous body can be treated with only one type of chemical, or with a combination of two or more types of chemicals.

[0050] The size (particle size) of the functional material 131 is not limited. However, if the functional material 131 is too small, it may easily fall off from the functional sheet 100 or may be difficult to handle. For this reason, the size of the functional material 131 is preferably a size that fits over a 200 mesh sieve specified in JIS Z8801, more preferably a size that fits over a 150 mesh sieve, and even more preferably a size that fits over a 100 mesh sieve. Furthermore, the particle size of the functional material 131 is preferably 50 μm or more, and more preferably a size that fits over 100 μm or more.

[0051] On the other hand, if the functional material 131 is too large, it becomes difficult to ensure a large specific surface area for the functional material 131, which may result in difficulty in enhancing the function of the functional material 131 exerted per unit area of ​​the functional sheet 100. For this reason, the size of the functional material 131 is preferably under a 5-mesh sieve specified in JIS Z8801, more preferably under a 7.5-mesh sieve, and even more preferably under a 10-mesh sieve. Furthermore, the particle size of the functional material 131 is preferably 5 mm or less, more preferably 3 mm or less.

[0052] The unit area (1 m) of the functional sheet 100 2 The amount F of functional material 131 held per unit area (the amount of functional material 131 dropped from the functional material hopper 20 (FIG. 3) and scattered onto the back-side substrate sheet 120) is not particularly limited. As already mentioned, in the device shown in FIG. 3, the powder-like functional material 131 is connected to each other with thread-like functional material adhesive 132, so that even if the amount of functional material 131 scattered is increased, the functional material 131 is less likely to fall off. The amount F of functional material 131 held per unit area is, for example, 50 [g / m 2 ] or more, or 100 [g / m 2 ] or more, or 150 [g / m 2 ] or more, or 200 [g / m 2 ] or more, or 250 [g / m 2 In the functional sheet 100 of this embodiment, the amount of the functional material 131 held by the sheet 100 can be set to 600 [g / m 2 It was confirmed that even when the retention amount F of the functional material 131 is 5000 [g / m ] or more, it is possible to prevent the functional material 131 from falling off. However, if the retention amount F of the functional material 131 becomes too large, there is a risk that the functional material 131 will easily fall off from the functional sheet 100. For this reason, the retention amount F of the functional material 131 is set to 5000 [g / m 2 ] or less, and 3000 [g / m 2 ] or less is more preferable.

[0053] The retention amount F of the functional material 131 also depends on the size of the functional material 131. That is, when the size of the functional material 131 is over a 100 mesh sieve (corresponding to a particle size of 134 μm or more) or under a 50 mesh sieve (corresponding to a particle size of 230 μm or less) specified in JIS Z8801, the retention amount F of the functional material 131 is set to 50 [g / m 2 ] or more 600[g / m 2 When the size of the functional material 131 is on an 80 mesh sieve (corresponding to a particle size of 138 μm or more) or under a 40 mesh sieve (corresponding to a particle size of 330 μm or less) as specified in JIS Z8801, the retention amount F of the functional material 131 is preferably 100 [g / m 2 ] or more 800[g / m 2When the size of the functional material 131 is on a 60 mesh sieve (corresponding to a particle size of 170 μm or more) or under a 30 mesh sieve (corresponding to a particle size of 450 μm or less) as specified in JIS Z8801, the retention amount F of the functional material 131 is preferably 150 [g / m 2 ] or more 1200[g / m 2 When the size of the functional material 131 is on a 40 mesh sieve (corresponding to a particle size of 330 μm or more) or under a 20 mesh sieve (corresponding to a particle size of 1.1 mm or less) as specified in JIS Z8801, the retention amount F of the functional material 131 is preferably 200 [g / m 2 ] or more than 2000[g / m 2 When the size of the functional material 131 is on a 30 mesh sieve (corresponding to a particle size of 450 μm or more) or under a 10 mesh sieve (corresponding to a particle size of 2.1 mm or less) as specified in JIS Z8801, the retention amount F of the functional material 131 is preferably 250 [g / m 2 ] or more than 2800[g / m 2 ] or less.

[0054] 5. Adhesive The type of functional material adhesive 132 varies depending on the application of the functional sheet 100 and the types of base sheets 110 and 120, but a hot melt type is preferably used. Examples of hot melt type adhesives include synthetic rubber hot melt adhesives, polyolefin hot melt adhesives, and EVA hot melt adhesives. Of these, synthetic rubber hot melt adhesives and polyolefin hot melt adhesives can be preferably used as the functional material adhesive 132. In particular, synthetic rubber hot melt adhesives are highly adhesive and therefore very suitable as the functional material adhesive 132.

[0055] Examples of base polymers (synthetic rubber) that can be used for synthetic rubber-based hot melt adhesives include styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene-styrene block copolymer (SBS), and styrene-ethylene-butylene-styrene block copolymer (SEBS). Base polymers can be used alone or in combination of two or more. Among these, SIS is particularly suitable as a base polymer for functional material adhesives 132 because of its high tensile elongation and excellent adhesive properties.

[0056] Various additives may be included in the functional material adhesive 132. Examples of additives include tackifiers (e.g., terpene resins, rosin resins, petroleum resins, etc.), plasticizers (e.g., paraffin oils, naphthene oils, aromatic oils, polybutene, polyisobutylene, etc.), and stabilizers (e.g., antioxidants, ultraviolet absorbers, etc.). One type of additive may be used alone, or two or more types may be used in combination.

[0057] In this embodiment, a mixture of styrene-isoprene-styrene block copolymer (SIS) and terpene resin is used as the functional material adhesive 132. It has also been confirmed that the functional material adhesive 132 generates almost no volatile organic compounds (VOCs) that can have adverse effects on the environment and human body.

[0058] The back-side adhesive 121 and the front-side adhesive 111 may each have the same configuration as that described for the functional material adhesive 132. The functional material adhesive 132, the back-side adhesive 121, and the front-side adhesive 111 may be of the same type or different types.

[0059] The content of adhesive in the functional sheet 100 (the total content of the functional material adhesive 132, the back-side adhesive 121, and the front-side adhesive 111; the same applies below) is not particularly limited. However, if the content of adhesive is too small, the functional material 131 may easily fall off, or the functional material layer 130 may easily peel off from the front-side substrate sheet 110 or the back-side substrate sheet 120. For this reason, the adhesive content per unit area (1 m) in the functional sheet 100 may be increased. 2 ) adhesive content [g / m 2 ] is the amount of functional material retained F [g / m 2 ] is preferably 0.1% or more, more preferably 0.5% or more, and even more preferably 1% or more. On the other hand, if the content of adhesive is too high, it may be difficult to improve the breathability of the functional sheet 100. For this reason, the content of adhesive in the functional sheet 100 [g / m 2 ] is the amount of functional material retained F [g / m 2 ] is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less.

[0060] 6. Physical properties of functional sheets The functional sheet 100 of this embodiment has a retention amount F of the functional material 131 of 50 [g / m 2 ] or more, high breathability (i.e., small pressure loss) can be achieved. Specifically, as will be shown in the examples below, when the pressure loss D [Pa] (surface air velocity 5.3 [cm / sec], measurement area 100 [cm 2 ]. The same applies below.) is calculated by dividing the pressure loss measured under the following conditions by the amount of functional material retained, F [g / m 2 ] (hereinafter referred to simply as "D / F") is 0.28 [km / s 2 In the functional sheet 100 of this embodiment, D / F can be set to 0.25 [km / s 2 ] or less, or 0.23 [km / s 2 ] or less, or 0.21 [km / s 2 ] or less.

[0061] The magnitude of the pressure loss D also varies depending on the amount F of the functional material 131 held. For example, in the functional sheet 100 of this embodiment, as will be shown in the examples below, when the amount F of the functional material 131 held is 100 [g / m 2 ] or more 150[g / m 2 When the loading amount F of the functional material 131 is 150 [g / m 2 ] or less, the pressure loss D can be 4 [Pa] or less. 2 ] more than 300 [g / m 2 ] or less, the pressure loss D can be set to 8 [Pa] or less, or 6 [Pa] or less. 2 ] more than 600 [g / m 2 When the loading amount F of the functional material 131 is 600 [g / m 2 ] or less, the pressure loss D can be set to 20 [Pa] or less, or 10 [Pa] or less. 2 ] more than 800 [g / m 2 ] or less, the pressure loss D can be set to 30 [Pa] or less, 20 [Pa] or less, or 12 [Pa] or less.

[0062] In the functional sheet 100 of this embodiment, the functional materials 131 are bonded to each other by the adhesive 132 for functional materials, so that the holding amount F of the functional materials 131 is, for example, 50 [g / m 2 ] or more, the functional material 131 is less likely to fall off. Specifically, the amount of functional material falling off at the time of cutting measured in the following steps 1 to 4 (hereinafter, sometimes simply referred to as "amount of functional material falling off at the time of cutting") can be set to 300 [mg] or less. The amount of functional material falling off at the time of cutting can be set to 100 [mg] or less, or 50 [mg] or less. In the functional sheet 100 of this embodiment, as will be shown in the examples later, the amount of functional material 131 held by the functional sheet 100 can be set to 600 [g / m 2 Even if the thickness is increased to 1000 [mg], the amount of functional material that falls off during cutting can be kept to 50 mg or less. Step 1: Take a 300mm square test piece from the functional sheet Step 2: Using a rotary cutter, make 10 cuts in each test piece that are roughly parallel to one side of the test piece and cross the test piece. Step 3: After cutting, gently shake the test piece while lifting it up, and collect and weigh any functional materials that have fallen off the test piece. Step 4: Repeat steps 1 to 3 three times, calculate the average weight [mg] of the functional material that fell off, and use this average as the amount of functional material that fell off during cutting. [Example]

[0063] The present invention will be described in more detail below with reference to more specific examples, but the embodiments of the present invention are not limited to the following examples.

[0064] [Experiment 1] An experiment was conducted to examine the pressure loss D of the functional sheet by changing the amount F of functional material held.

[0065] <Production of functional sheets> Example 1 The amount of functional material retained F is 50 [g / m 2 The functional sheet of Example 1, which has a surface roughness of 1000 nm and a thickness of 1000 nm, was produced using the apparatus shown in Figure 3. Untreated granular activated carbon was used as the functional material. The adhesive for the functional material, the front-side adhesive, and the front-side adhesive were all made by mixing SIS with a terpene resin. The adhesive content [g / m 2 ] is the amount of functional material retained F [g / m 2 ] was set at approximately 10%.

[0066] Examples 2 to 5 The amount of functional material retained, F, was set to 150 [g / m 2 ], and 300 [g / m 2 ], and in Example 4, 600 [g / m 2 ], and in Example 5, 800 [g / m 2 The functional sheets of Examples 2 to 5 were produced under the same conditions as in Example 1, except that:

[0067] (Comparative Examples 1 to 5) Functional sheets of Comparative Examples 1 to 5 were produced under the same conditions as Examples 1 to 5, respectively, except that the apparatus shown in Figure 7 (sinter method) was used instead of the apparatus shown in Figure 3, and an EVA-based hot melt adhesive was used as the adhesive.

[0068] <Pressure loss measurement> For each of the functional sheets of Examples 1 to 5 and Comparative Examples 1 to 5, the surface wind speed was 5.3 [cm / sec], and the measurement area was 100 [cm 2 ], the pressure loss D [Pa] was measured and the pressure loss D [Pa] was calculated based on the functional material loading F [g / m 2 ] divided by D / F [km / s 2 The results are shown in Table 1 below.

[0069] [Table 1]

[0070] Figure 5 shows the D / F [km / s 2 ] and functional material retention amount F [g / m 2 5. As shown in Table 1 and FIG. 5, in the examples, the pressure loss D and D / F values ​​were both lower than in the comparative examples with the same functional material loading F. In Examples 2 to 5 (functional material loading F: 150 [g / m 2 ] or more), the value of D / F is 0.021 [km / s 2 In contrast, in Comparative Examples 2 to 5, the D / F value was 0.029 [km / s 2 ]That was all.

[0071] [Experiment 2] An experiment was conducted to examine the amount of functional material that fell off when the sample functional sheet was cut.

[0072] <Production of functional sheets> Example 6 The functional sheet of Example 6 was produced using the apparatus shown in Figure 3. Untreated granular activated carbon was used as the functional material. The adhesive for the functional material, the front-side adhesive, and the front-side adhesive were all made by mixing SIS with a terpene resin. The functional material loading F was 600 [g / m 2 ]. Adhesive content [g / m 2 ] is the amount of functional material retained F [g / m 2 ] (60 [g / m 2 ]).

[0073] (Comparative Example 6) The functional sheet of Comparative Example 6 was produced under the same conditions as in Example 6, except that the apparatus shown in Figure 7 (sinter method) was used instead of the apparatus shown in Figure 3, and an EVA-based hot melt adhesive was used as the adhesive.

[0074] <Measurement of the amount of functional material that falls off when cutting> The amount of functional material that fell off upon cutting [mg] was measured for each of the functional sheets of Example 6 and Comparative Example 6 using the above-described procedures 1 to 4. Figure 6 is a photograph showing the results of Experiment 2. Figure 6(a) is a photograph of the functional material that fell off from the functional sheet of Example 6, and Figure 6(b) is a photograph of the functional material that fell off from the functional sheet of Comparative Example 6. As shown in Figure 6, the amount of functional material that fell off in Example 6 was overwhelmingly less than that in Comparative Example 6. The amount of functional material that fell off upon cutting in Example 6 was 42 [mg], while the amount of functional material that fell off in Comparative Example 6 was 546 [mg].

[0075] [Experiment 3] An experiment was conducted to evaluate the performance of the functional sheet 100 according to the present invention. The experimental results are shown in Table 2 below. "Example 7" in Table 2 relates to the functional sheet 100 according to the present invention, and "Comparative Example 7" relates to a functional sheet 900 (FIG. 8) manufactured using the sintering method (FIG. 7). In both Example 7 and Comparative Example 7, the types of nonwoven fabrics used as the base sheets 110, 120, 910, and 920 and the types of functional materials 131 and 930 (activated carbon) were the same. The retention amount F of the functional materials 131 and 930 (activated carbon) in the functional sheets 100 and 900 was also 135 [g / m 2 ] were used. However, due to differences in manufacturing methods, in Example 7, a synthetic rubber-based hot melt adhesive was used as the functional material adhesive 132, the back-side adhesive 121, and the front-side adhesive 111, whereas in Comparative Example 7, an EVA-based hot melt adhesive was used as the adhesive 940. Among the "measurement items" in Table 2, the "amount of functional material falling off" was measured by placing functional sheets 100 cut to the same dimensions in a bag, dropping them from a height of 1 meter 10 times, and then removing the functional sheets 100, 900 from the bag and measuring the weight of the functional materials 131, 930 inside the bag.

[0076] [Table 2]

[0077] As can be seen from Table 2 above, Example 7 has a greater "thickness" than Comparative Example 7. This is because, in Comparative Example 7, sufficient peel strength could not be achieved unless the gap between the pressure rollers 91 and 92 (FIG. 7) was approximately 0.3 mm, whereas in Example 7, sufficient peel strength could be achieved even when the gap between the pressure rollers 91 and 92 (FIG. 3) was wider, at approximately 0.5 mm. Therefore, Example 7 has a higher "breathability" and a lower "airflow resistance" than Comparative Example 7. Furthermore, although there was no significant difference in "bending resistance (vertical)" between Example 7 and Comparative Example 7, Example 7 has a significantly smaller "bending resistance (horizontal)" than Comparative Example 7. This demonstrates that the functional sheet 100 of Example 7 is easier to make flexible.

[0078] Particularly noteworthy are the "peel strength" and "amount of functional material that fell off." As described above, despite the fact that the gap between the pressure rollers 91, 92 was wider in Example 7 and the pressure applied to the base sheets 110, 120 was lower (and furthermore, despite the fact that the amount of adhesive used was less in Example 7), the "peel strength" was clearly higher in Example 7. Furthermore, the "amount of functional material that fell off" in Example 7 was reduced to about 1 / 12 of that in Comparative Example 7. From the above experimental results, it was found that the functional sheet 100 according to the present invention can exhibit excellent effects in terms of peel strength and resistance to functional material fall-off, even while increasing the thickness of the functional sheet 100, improving breathability, and making it flexible. [Explanation of symbols]

[0079] 10 Base sheet transport means 11. Feed roller (for back side base sheet) 12 Winding roller 20 Functional material hopper 21 Discharge roller 30 Functional material dispersion means 40 Functional material adhesive discharge means 41 Adhesive outlet 42 Tank-shaped member 43 Air outlet 50 Functional Material Slider 60 Back side adhesive discharging means 70 Front side adhesive discharge means 80 Integration base sheet feeding means 81 Feed roller (for front side base sheet) 90 Pressing Methods 91 Pressure roller (upper side) 92 Pressure roller (lower) 99 Heating Furnace 100 Functional Sheet 110 Front side base sheet (base sheet) 111 Front side adhesive 120 Back side base sheet (base sheet) 121 Backside adhesive 130 Functional material layer 131 Functional Materials 132 Adhesives for functional materials 900 Functional Sheet 910 Base Sheet 920 Base sheet 930 Functional Materials 940 Adhesive α The location where the adhesive is discharged by the adhesive discharge means for functional materials θ Tilt angle of the slider for functional materials

Claims

1. A breathable functional sheet in which a functional material layer is sandwiched between a front substrate sheet and a back substrate sheet, The functional material layer is A granular functional material, A thread-like adhesive that connects functional materials together by being entangled in the functional materials. Equipped with A functional sheet characterized by:

2. 2. The functional sheet according to claim 1, wherein the functional material layer and the front substrate sheet, and the functional material layer and the back substrate sheet are bonded together by a thread-like adhesive, respectively.

3. Adhesive content [g / m ２ ] is the amount of functional material retained F [g / m ２ 2. The functional sheet according to claim 1, wherein the thickness is 40% or less of the thickness of the functional sheet.

4. The amount of functional material retained F is 50 [g / m ２ 2. The functional sheet according to claim 1, wherein the thickness is at least 100 μm.

5. Surface wind speed 5.3 [cm / sec], measurement area 100 [cm] ２ The pressure loss D [Pa] measured under the conditions of ２ ] is 0.28 [km / s ２ 5. The functional sheet according to claim 4, wherein the thickness is 100 μm or less.

6. 5. The functional sheet according to claim 4, wherein the amount of functional material that falls off when cut is 300 mg or less, as measured by the following procedures 1 to 4. Step 1: Take a 300 mm square test piece from the functional sheet Step 2: Using a rotary cutter, make 10 cuts in each test piece that are approximately parallel to one side of the test piece and cross the test piece. Step 3: After cutting, gently shake the test piece while lifting it up, and collect and weigh any functional material that has fallen off the test piece. Step 4: Repeat steps 1 to 3 a total of three times, calculate the average weight [mg] of the functional material that fell off, and use this average as the amount of functional material that fell off during cutting.

7. The functional sheet according to claim 1, wherein the front substrate sheet and the back substrate sheet are made of sheet materials having an elongation of 20% or more as measured in accordance with JIS L1913 (2010).

8. The functional sheet according to claim 1, wherein the front substrate sheet and the back substrate sheet are made of a sheet material having a stiffness of 6 [mN] or less as measured by the Gurley method in accordance with JIS L1913 (2010).

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