Filter and method for manufacturing filter

Abstract

A filter (1) comprises a filter body (11) made of a nonwoven fabric. The filter body (11) includes: an indicator part (13) that is formed by laminating a resin film on the surface of the nonwoven fabric and displays or indicates replacement timing in accordance with use; and an air-permeable part (12), which is a portion other than the indicator part (13). In a Lab color space, the difference Δb (b' - b) between the b value (b) in the indicator part (13) and the b value (b') in the air-permeable part (12) is from -1 to +1, inclusive, before the filter is used. With this configuration, it is difficult to visually recognize the difference in color between the indicator part (13) and the air-permeable part (12) before the filter is used. The indicator part (13) is therefore less likely to be visually recognized before the filter is used, reducing the possibility of incorrect determination of the replacement timing. As the filter is used, the difference in color between the indicator part (13) and the air-permeable part (12) develops, so that the indicator part (13) can display or indicate the replacement timing.

Description

Filter and method for manufacturing a filter

[0001] This invention relates to filters and methods for manufacturing filters, and more particularly to filters and methods for manufacturing filters used to prevent soiling in range hoods, air conditioners, air purifiers, ventilation fans and vents, HVAC systems, etc.

[0002] As a filter used to prevent dirt buildup in range hoods, exhaust fans, and vents, for example, there is one shown in Patent Document 1 (Japanese Patent No. 4855240).

[0003] The indicator filter described in Patent Document 1 (Japanese Patent No. 4855240) consists of a filter body made of nonwoven fabric that is attached to the underside of a range hood, and an indicator part formed on a part of the surface of the filter body. The indicator part is made of resin film and is non-breathable, preventing the passage of oil fumes and the like.

[0004] In such indicator-equipped films, the filter sheet and filter body gradually discolor due to the accumulation of oil fumes, while the replacement sign and indicator area do not discolor because they are not breathable and prevent the passage of oil fumes. As a result, the replacement sign and indicator area become visible as white on the front of the filter as it is used, allowing the user to recognize that the filter has reached the end of its replacement period.

[0005] Japanese Patent No. 4855240

[0006] However, in conventional filters as described above, the resin film can discolor due to hydrolysis, heat, and UV degradation. Therefore, if the resin film discolors due to degradation, the indicator part may become visible even when the filter is unused, potentially leading to user misinterpretation. In such cases, it may be difficult to correctly determine when to replace the filter, and users may replace the filter before it is properly replaced, potentially resulting in unnecessary costs and environmental burdens due to the disposal of unnecessary filters.

[0007] This invention was made to solve the above-mentioned problems, and aims to provide a filter and a method for manufacturing the filter that reduces the risk of misinterpreting the replacement time when the filter is not in use.

[0008] To achieve the above objective, the filter in the first aspect of this invention is a filter that is replaceably attached to an object and comprises a filter body made of nonwoven fabric, wherein the filter body comprises an indicator part formed by laminating a resin film on the surface of the nonwoven fabric and indicating or suggesting the time for replacement as it is used, and a ventilation part other than the indicator part, wherein in the Lab system, the difference Δb(b'-b) between the b value (b) in the indicator part when not in use and the b value (b') in the ventilation part is between -1 and +1.

[0009] With this configuration, the first effect is obtained: when not in use, it becomes difficult to visually recognize the difference in color between the indicator section and the ventilation section.

[0010] In the second aspect of this invention, the filter, in the configuration of the invention in the first aspect, is composed of one type of resin or a mixture of multiple types of resins selected from the group consisting of polyethylene resin, polypropylene resin, polyester resin, polyvinyl butyral resin, acrylic resin, ABS resin, and ethylene vinyl acetate copolymer resin.

[0011] This configuration provides favorable adhesion of the resin film to the nonwoven fabric, as well as high transparency and resistance to discoloration over time, which are the two advantages of this configuration.

[0012] In the third aspect of this invention, the filter, in the configuration of the invention in the first or second aspect, has a basis weight of 30 g / m² for the filter body. ２ More than 200g / m ２ The following applies:

[0013] This configuration provides the effect 3, which means that the weight of constituent fibers per unit area of ​​the nonwoven fabric falls within a suitable range.

[0014] In the fourth aspect of this invention, the filter, in the configuration of the invention in the first or second aspect, has flame retardancy as its filter body.

[0015] This configuration provides the benefit (4) of improved heat resistance of the filter body.

[0016] The filter in the fifth aspect of this invention is the configuration of the invention in the first or second aspect, wherein the object is a range hood or a ventilation fan.

[0017] This configuration provides the effect 5 that the indicator part of the filter attached to the range hood or ventilation fan is less likely to discolor with use.

[0018] The filter in the sixth aspect of this invention is the configuration of the invention in the first or second aspect, wherein the object is an HVAC system.

[0019] This configuration provides the effect 6 that the indicator part of the filter attached to the HVAC system is less likely to change color due to use.

[0020] A seventh aspect of this invention is a method for manufacturing a filter that can be replaced and attached to an object, comprising a preparation step of preparing a filter body made of nonwoven fabric, and an indicator part formation step of laminating a resin film on a part of the surface of the filter body to form an indicator part that displays or suggests the time for replacement as it is used, wherein in the Lab system, the difference Δb(b'-b) between the b value (b) in the indicator part and the b value (b') in the ventilation part which is the part other than the indicator part is between -1 and +1.

[0021] With this configuration, the effect 7 is obtained in which it becomes difficult to visually recognize the difference in color between the indicator part and the ventilation part when not in use.

[0022] In a filter manufacturing method according to an eighth aspect of the present invention, in the configuration of the invention according to the seventh aspect, in the indicator portion forming step, a resin film is laminated by transferring onto a part of a surface of a filter body using a transfer film obtained by applying a resin ink to a surface of a release film.

[0023] With this configuration, the effect 8 that the surface of the resin film becomes smooth is obtained.

[0024] In a filter manufacturing method according to a ninth aspect of the present invention, in the configuration of the invention according to the eighth aspect, in the indicator portion forming step, transfer is performed by hot-pressing the transfer film against a part of a surface of the filter body.

[0025] With this configuration, the effect 9 that the resin on the transfer film is transferred in a softened or molten state by hot pressing is obtained.

[0026] In a filter manufacturing method according to a tenth aspect of the present invention, in the configuration of the invention according to any one of the seventh to ninth aspects, the resin film is formed of one type of resin or a mixed resin of two or more types selected from the group consisting of polyethylene resin, polypropylene resin, polyester resin, polyvinyl butyral resin, acrylic resin, ABS resin, and ethylene-vinyl acetate copolymer resin.

[0027] With this configuration, the effect 10 that the adhesion of the resin film to a nonwoven fabric is favorable, the transparency is high, and discoloration over time is less likely to occur is obtained.

[0028] As described above, since the filter according to the first aspect of the present invention obtains the above-described effect 1, it is possible to reduce the risk that the indicator portion is difficult to visually recognize when unused and causes misidentification of the replacement time, and a color difference from the ventilation portion occurs with use, so that the replacement time can be displayed or suggested.

[0029] The filter in the second aspect of this invention, in addition to the effects of the invention in the first aspect, also provides the above-mentioned effect 2, thereby reducing the risk of the resin film being damaged during lamination. Furthermore, even if time has passed between manufacturing and use, Δb is more likely to maintain a favorable value.

[0030] The filter in the third aspect of this invention, in addition to the effects of the invention in the first or second aspect, also provides the above-mentioned effect 3, resulting in favorable adhesion to the resin film. Furthermore, it does not have high transparency, reducing the risk of the resin film being visible when the indicator part is viewed from the nonwoven fabric side. Moreover, it can more reliably perform the function of displaying or suggesting the replacement time of the indicator part.

[0031] The filter in the fourth aspect of this invention, in addition to the effects of the invention in the first or second aspect, also provides the above-mentioned effect 4, and therefore can be suitably used even for objects that may become hot during use.

[0032] The filter in the fifth aspect of this invention is suitable as a filter for preventing dirt buildup on range hoods and kitchen ventilation fans because, in addition to the effects of the invention in the first or second aspect, it also provides the above-mentioned effect 5.

[0033] The filter in the sixth aspect of this invention is suitable as a filter for an HVAC system because, in addition to the effects of the invention in the first or second aspect, the above-mentioned effect 6 is obtained.

[0034] The seventh aspect of this invention provides a method for manufacturing a filter in which the above-mentioned effect 7 is obtained, thereby reducing the risk of misinterpreting the replacement time because the indicator part is difficult to see when not in use, and allowing the replacement time to be indicated or suggested by the color difference between the indicator part and the ventilation part as it is used.

[0035] The filter manufacturing method in the eighth aspect of this invention, in addition to the effects of the invention in the seventh aspect, provides the above-mentioned effect 8, thereby reducing the risk that fine surface irregularities may affect the visibility of the indicator part.

[0036] The filter manufacturing method in the ninth aspect of this invention, in addition to the effects of the invention in the eighth aspect, also provides the above-mentioned effect 9, so that the resin film can be more reliably laminated onto the filter body in the intended form.

[0037] The filter manufacturing method in the tenth aspect of this invention, in addition to the effects of the invention in any of the seventh to ninth aspects, also provides the above-mentioned effect 10, thereby reducing the risk of the resin film being damaged during lamination. Furthermore, even if time has passed between manufacturing and use, Δb is more likely to maintain a favorable value.

[0038] This is a perspective view showing the installation state of the filter according to an embodiment of this invention. This is an enlarged view of the X portion shown in Figure 1, where (1) shows the state when not in use and (2) shows the state when it is time to replace the filter due to continued use. This is an enlarged cross-sectional view of the line III-III in Figure 1, with the thickness exaggerated. This is a diagram showing the filter according to an embodiment of this invention applied to an HVAC system.

[0039] Figure 1 is a perspective view showing the state in which the filter according to an embodiment of this invention is attached to a range hood, and Figure 2 is an enlarged view of the X portion shown in Figure 1, where (1) shows the state when not in use and (2) shows the state when it is time to replace the filter due to continued use.

[0040] Referring to Figure 1, the range hood consists of a boot-shaped hood with an air intake on the inside. A metal filter 50 is installed at the opening of the air intake to prevent foreign objects from entering the inside of the air intake. The filter 1 consists of a filter body 11 made of nonwoven fabric and is replaceable by being attached to the underside of the metal filter 50 via a magnet or the like (not shown).

[0041] The filter body 11 has a rectangular shape and includes a ventilation section 12 which is the part that performs the filtration function of the filter 1, and an indicator section 13 which is formed in a part of the filter body 11 and indicates or suggests when it is time to replace the filter as it is used.

[0042] The ventilation section 12 refers to the part of the filter body 11 other than the indicator section 13, and since it is made of nonwoven fabric, it has a high degree of breathability. As a result, when air containing oil fumes, etc. passes through, the oil fumes, etc. are sufficiently captured in the ventilation section 12, and the ventilation section 12 changes color, making it a filter 1 that can be suitably used in range hoods and the like. The indicator section 13 may be formed on either the front surface (the surface opposite to the surface facing the metal filter 50) or the back surface (the surface facing the metal filter 50) of the filter body 11.

[0043] Referring to Figure 2, the indicator section 13 is a part that allows visual confirmation and determination of when the filter 1 needs to be replaced due to contamination of the filter 1 by airborne pollutants such as oil fumes and dust. It is constructed by laminating a resin film on the surface of the nonwoven fabric that makes up the filter body 11. Therefore, the indicator section 13 has low air permeability.

[0044] Here, we will explain the visibility of the indicator unit 13 before and after use. In this invention, "before use" refers to the time before the user starts using the filter 1, and may be a short time since manufacture, or several years may have passed.

[0045] Referring to Figure 2(1), in the unused state, the indicator section 13 has a colorless, transparent resin film laminated on the nonwoven fabric surface, making it difficult to visually distinguish the color difference between the indicator section 13 and the ventilation section 12, as will be described in detail later. Furthermore, as mentioned above, the indicator section 13 has low breathability and does not easily collect dirt such as oil fumes from the air, so it does not easily change color even with continued use. On the other hand, the ventilation section 12 collects dirt such as oil fumes from the air and therefore changes color. As a result, as time passes, as shown in Figure 2(2), the ventilation section 12 changes color, causing the indicator section 13 to become white and clearly readable. Therefore, the user will not misidentify the presence of the indicator section 13 when it is not in use, while after use, the indicator section 13 will be clearly visible, allowing the user to appropriately confirm the replacement time. It should be noted that regardless of whether the indicator section 13 is formed on the front or back surface of the filter body 11, the indicator section 13 will become white as time passes, allowing the user to appropriately confirm the replacement time.

[0046] Next, we will explain in detail the difference in color between the indicator section 13 and the ventilation section 12 when not in use.

[0047] As shown in Figure 2(1), when the indicator section 13 and ventilation section 12 are not in use, the difference Δb(b'-b) between the b value (b) in the indicator section 13 and the b value (b') in the ventilation section 12 is between -1 and +1 in the Lab system (L*a*b* color space).

[0048] With this configuration, it becomes difficult to visually recognize the color difference between the indicator section 13 and the ventilation section 12 when not in use. This reduces the risk of misjudging the replacement time because the indicator section 13 is difficult to see when not in use, while the color difference between it and the ventilation section 12 becomes apparent with use, allowing the replacement time to be displayed or suggested.

[0049] The Lab system is a color system index for representing the color of objects. It is a three-dimensional color space obtained by plotting the quantities L (L*), a (a*), and b (b*), as defined in JIS Z 8781-4, on a Cartesian coordinate system. In the Lab system, lightness is represented by L, and chromaticity, which indicates hue and saturation, is represented by a and b. +a indicates the red direction, -a indicates the green direction, +b indicates the yellow direction, and -b indicates the blue direction. The larger the value, the more vivid the color.

[0050] The b-value is measured in accordance with JIS Z 8722, using the indicator section 13 and the ventilation section 12 as the target objects. Let the b-value in the indicator section 13 be b, and the b-value in the ventilation section 12 be b'. The difference Δb, obtained by b'-b, is configured to be between -1 and +1. For example, Δb can be adjusted by appropriately changing the resin composition of the resin film used in the indicator section 13. The b-value in the indicator section 13 may be measured by measuring the resin film of the indicator section 13 itself, or by measuring from the opposite side of the nonwoven fabric on which the resin film is formed. For example, if the indicator section 13 is formed on the surface of the filter body 11, measuring the indicator section 13 from the surface will measure the b-value of the resin film itself, while measuring the indicator section 13 on the back will measure the b-value of the resin film through the nonwoven fabric. Regardless of the measurement angle, if Δb is within a predetermined range, it becomes difficult to visually recognize the color difference between the indicator section 13 and the ventilation section 12 when not in use. This reduces the risk of misjudging the replacement time due to the indicator section 13 being difficult to see when not in use, and allows the color difference between it and the ventilation section 12 to appear with use, thereby indicating or suggesting the replacement time. In particular, if Δb is within a predetermined range when measuring the resin film of the indicator section 13 itself, it becomes even more difficult to visually recognize the color difference between the indicator section 13 and the ventilation section 12 when viewed from the side opposite to the side on which the indicator section 13 is formed via the nonwoven fabric. This further reduces the risk of misjudging the replacement time due to the indicator section 13 being difficult to see when not in use, and allows the color difference between it and the ventilation section 12 to appear with use, thereby reliably indicating or suggesting the replacement time.

[0051] The resin film used in the indicator section 13 is preferably composed of one type of resin or a mixture of several types of resins selected from the group consisting of polyethylene (PE) resin, polypropylene (PP) resin, polyester resin, polyvinyl butyral (PVB) resin, acrylic resin, acrylonitrile butadiene styrene (ABS) resin, and ethylene vinyl acetate copolymer (EVA) resin. This configuration ensures good adhesion of the resin film to the nonwoven fabric, thereby reducing the risk of the resin film being damaged during lamination. Furthermore, because it has high transparency and is less prone to discoloration over time, Δb is more likely to maintain a favorable value even after a period of time has passed from manufacturing to use. The mixed resin can be obtained by kneading multiple types of resins, for example, by a known method.

[0052] Furthermore, when the resin film is composed solely of polyethylene resin, the specific gravity is 0.9 g / cm³. ３ ~1.0 g / cm ３ Preferably, the melting index (melt flow index (melt flow rate)) measured by JIS K 7210 A method is 45 g / 10 min to 55 g / 10 min, and the softening point is 110°C to 115°C. With this configuration, good adhesion to the nonwoven fabric fibers is achieved, and high heat is not applied to the nonwoven fabric fibers, thus enabling the formation of a polyethylene resin film while reducing resin charring and thermal degradation.

[0053] Furthermore, it is more preferable that the resin film used in the indicator section 13 is composed of one or more types of resins selected from the group of resins consisting of polypropylene resin (PP resin), polyester resin, polyvinyl butyral resin, acrylic resin, ABS resin, and ethylene vinyl acetate copolymer resin, or a mixed resin of at least one type of resin selected from the said group and polyethylene resin. This configuration makes it less likely for discoloration to occur over time, making it easier to adjust Δb when not in use.

[0054] Furthermore, when using a mixed resin, it is preferable that it contains polyvinyl butyral resin and acrylic resin. With this configuration, the transparency of the resin film is high and the light resistance (degree of resistance to discoloration when exposed to light) is good. The mixing ratio of polyvinyl butyral resin is preferably 5% by weight or more and 100% by weight or less (single) of the total amount of the mixed resin (100% by weight). With this configuration, it is easier to control the Δb value to a suitable numerical range. Furthermore, it is even more preferable that it be 50% by weight or more and 90% by weight or less. With this configuration, adhesion to the nonwoven fabric is improved when laminating to the nonwoven fabric, and if desired, the effect of improving heat resistance can also be provided. In this case, the remaining resin can be low-density polyethylene resin, polyvinyl acetate resin, ABS resin, PP resin, ethylene vinyl acetate copolymer resin, etc. Low-density polyethylene resin, polyvinyl acetate resin, and ethylene vinyl acetate copolymer resin have the effect of improving adhesion to the nonwoven fabric, while ABS resin and PP resin have the effect of improving transparency and heat resistance. If the adhesion of the resin film to the nonwoven fabric is poor, when a release film or release paper for transfer applications (hereinafter collectively referred to as "transfer film") is heat-pressed so that the nonwoven fabric surface and the resin surface overlap, a portion of the resin film laminated on the transfer film may not adhere to the nonwoven fabric surface and may remain on the transfer film surface, potentially causing defects such as chipping or holes in the shape of the resin film in filter 1. Therefore, by improving the adhesion to the nonwoven fabric, the release properties from the transfer film are improved, and a filter 1 can be constructed in which the resin film is suitably laminated on the nonwoven fabric.

[0055] To manufacture such a filter 1, a preparation step is made to prepare a filter body 11 made of nonwoven fabric, and an indicator part formation step is made to laminate a resin film on a part of the surface of the filter body 11 to form an indicator part 13 that displays or suggests the replacement time as it is used. In the Lab system, the difference Δb(b'-b) between the b value (b) in the indicator part 13 and the b value (b') in the ventilation part 12, which is the part other than the indicator part 13, should be set to be between -1 and +1. With this configuration, it is difficult to visually recognize the color difference between the indicator part 13 and the ventilation part 12 when not in use, thus reducing the risk of misjudging the replacement time because the indicator part 13 is difficult to see when not in use, and allowing the color difference between it and the ventilation part 12 to appear as it is used, thereby displaying or suggesting the replacement time.

[0056] Furthermore, the material of the nonwoven fabric constituting the filter body 11 is not particularly limited, and nonwoven fabrics made of polyester such as polyethylene terephthalate (PET), polypropylene, polypropylene as a single material or copolymer mainly composed of polyester and polypropylene, or synthetic resin fibers such as modacrylic or acrylic can be used, but are not limited to these. The manufacturing method of the nonwoven fabric is also not limited, and nonwoven fabrics manufactured by known methods such as chemical bonding or thermal bonding can be suitably used. In addition, the nonwoven fabric may be treated with antiviral or antibacterial processing. Furthermore, for the purpose of imparting flame retardancy, an appropriate amount of phosphorus-based flame retardant, halogen-based or non-halogen-based flame retardant, fatty acid metal salts such as aluminum stearate can be attached to the above-mentioned synthetic resin fibers, or flame-retardant fibers can be mixed in, making it possible to create a filter suitable for use in applications where flame retardancy is desirable, such as for range hoods. Furthermore, the desired air permeability and filtration performance can be provided according to the application.

[0057] By configuring the filter body to be flame-retardant, the heat resistance of the filter body is improved, making it a suitable filter for use with objects that may become hot during use.

[0058] The filter body (nonwoven fabric) has a basis weight of 30 g / m². ２More than 200g / m ２ The following is preferable. With this configuration, the weight of constituent fibers per unit area of ​​the nonwoven fabric falls within a suitable range. The basis weight of the nonwoven fabric is 30 g / m². ２ As a result of meeting the above conditions, the weight of the constituent fibers per unit area becomes sufficient, and the adhesion with the resin film is favorable, making it easier to lay the resin film favorably on the surface of the nonwoven fabric. Furthermore, the basis weight of the nonwoven fabric is 200 g / m². ２ The following features reduce transparency, minimizing the risk of the resin film being visible when the indicator is viewed from the nonwoven fabric side. Furthermore, it allows for a more reliable display or indication of when the indicator needs replacing.

[0059] In the indicator part formation process, the method of laminating the resin film using the resin described above is not particularly limited, but the following methods can be employed: preparing a heat-sealable film that has been pre-cut to the same shape as the indicator part, supplying the cut film piece to a desired position on the surface of the nonwoven fabric, and pressing it while heating it with a heat press or heat press plate of the same shape as the indicator part; or simultaneously cutting the heat-sealable film, supplying the film piece to the surface of the nonwoven fabric, and heating and pressing the film piece to fuse and laminate the film piece onto the nonwoven fabric (fusion method); applying resin ink to the surface of the nonwoven fabric to laminate the resin film (coating method); and using a transfer film made by applying resin ink to the surface of a release film to transfer it to a part of the surface of the filter body to laminate the resin film (transfer method). Among these, the transfer method has better productivity efficiency than the film fusion method, and the surface of the resin film becomes smooth, so fine surface irregularities are less likely to occur on the surface of the resin film as in the coating method, thereby reducing the risk of the indicator part being visible before the filter is used.

[0060] Specifically, the release film is a sheet-like material made by coating a base material such as a resin film or paper with a release agent. For example, a film in which silicone resin is printed on the entire surface of a polyethylene terephthalate (PET) film (hereinafter referred to as "silicone PET film" for convenience) can be used. A resin ink made of the aforementioned resin is printed on the silicone resin-printed surface of such a release film in a desired amount to prepare a transfer film. The transfer film is then placed on the surface of a part of the filter body 11 (the area where the indicator part 13 is to be installed) so that the resin surface is in contact with it, and the resin film is transferred. At this time, it is preferable that the resin film is transferred to the nonwoven fabric surface by heating and pressing the transfer film against the surface of a part of the filter body 11. With this configuration, the resin on the transfer film is softened or melted by heating and pressing, so that the resin film can be laminated onto the filter body 11 in the intended form more reliably.

[0061] The temperature range for the heat press is not particularly limited and can be adjusted as appropriate according to the properties of the fibers constituting the nonwoven fabric used, such as the melting point. However, setting the temperature appropriately between 70°C and 250°C will allow for the formation of a resin film while reducing charring and thermal degradation of the resin.

[0062] Furthermore, there are no restrictions on the pressure of the heating press, but it is preferably between 0.2 MPa and 2.0 MPa, and more preferably between 0.4 MPa and 1.5 MPa.

[0063] Furthermore, there are no restrictions on the heating press time, but it is preferably between 0.2 seconds and 5.0 seconds, and more preferably between 0.4 seconds and 3.0 seconds.

[0064] The position and range in which the resin film is laminated on the filter body 11 are not particularly limited, but since this is the position where the indicator section 13 is provided, it is sufficient that the air permeability and filtration performance of the filter 1, and the indicator function of the indicator section 13 during use, are performed without any problems.

[0065] Figure 3 is an enlarged cross-sectional view along the line III-III in Figure 1, with the thickness exaggerated for illustrative purposes.

[0066] Referring to Figure 3(1), in the indicator section 13, due to the heating press in the indicator section formation process, some of the fibers of the nonwoven fabric of the pressed filter body 11 melt and bond, or the nonwoven fabric is deformed and maintained in a compressed state, resulting in a partial increase in density and a decrease in thickness in that area, while a resin film is laminated on the surface of the nonwoven fabric of the filter body 11.

[0067] Furthermore, referring to Figure 3(2), in another embodiment, the indicator portion 23 is formed by lowering the temperature conditions of the heating press in the indicator portion formation process, so that the thickness of the filter body 21 is maintained without melting or deforming, and a resin film is laminated on the nonwoven fabric surface of the filter body 21.

[0068] Regardless of the configuration, there is no significant difference in visibility when viewing the indicator sections 13 and 23 from the front, and the b-value of the indicator sections 13 and 23 when not in use does not change fundamentally, so any desired configuration can be adopted.

[0069] In the above embodiment, the indicator part had a rectangular shape, but it may be any geometric shape such as a heart, triangle, or star. Also, the indicator part is not limited to a mark, but may be letters, patterns, etc. Furthermore, in the above embodiment, the indicator part indicated the time to replace the product by making the user see a specific shape after use, but it may also be a sign indicating the time to replace the product, for example, a string of characters such as "Please replace it" that the user sees.

[0070] Furthermore, in the above embodiment, the filter body was attached to the object by a magnet. However, it may also be a structure in which the filter body is integrated with the frame by being bonded to the frame so as to cover the opening of the frame, with a frame body formed from metal foil such as aluminum foil and having a desired opening formed to correspond to the shape of the air intake of the range hood or the propeller of the ventilation fan. Alternatively, the end of such a metal foil frame body may be slidably engaged with the end of another similar frame body (for example, a structure in which a rim is formed on the ends of two frame bodies, and the rims of one frame body and the other frame body are slidably engaged with each other). With such a configuration, one frame body can be pre-shaped to correspond to the range hood or ventilation fan. Also, in the case of a structure composed of multiple frame bodies, the size of the filter can be changed by sliding the frame bodies. Therefore, it becomes possible to adjust the length of the filter according to the size of the range hood, improving ease of use.

[0071] Furthermore, while the above embodiment involved a range hood to which the filter was attached, the present invention can be used to prevent dirt buildup in places where air enters and exits, such as ventilation devices like exhaust fans, indoor and outdoor vents, air conditioners, air purifiers, and the ventilation parts of bathroom doors, in addition to range hoods. The size and shape of the filter can also be appropriately changed depending on the application. By using a range hood or exhaust fan as the target object, the indicator part of the filter attached to the range hood or exhaust fan is less likely to discolor with use, making it suitable as a filter for preventing dirt buildup on range hoods and exhaust fans around kitchens.

[0072] Furthermore, although the object in the above embodiment was a range hood, the present invention can also be applied to filters installed in HVAC (Heating, Ventilating, Air-Conditioning) systems. An HVAC system is a complex system consisting of multiple devices and control devices for controlling air temperature and ventilation, and is usually composed of outlets, heating systems, cooling systems, etc., which are usually integrated into a single system and are sometimes simply referred to as HVAC. Such an HVAC system incorporates an HVAC filter for the purpose of filtering the air. HVAC filters are used for air filtration in cases where they are attached to the HVAC unit, or attached to the back of the return grill in addition to the HVAC unit, or placed in any other location in the HVAC system. HVAC filters capture dust and dirt as the HVAC system operates and become dirty in about one to two months, so they are replaced periodically.

[0073] Figure 4 shows a filter according to an embodiment of this invention applied to an HVAC system.

[0074] To explain in detail, referring to Figure 4, the HVAC filter 5 is used by being removably attached to an HVAC unit (not shown) of the HVAC system. The HVAC filter 5 consists of a pleated HVAC filter base material 51, which is either a single-layer configuration of the filter according to the present invention or a multi-layer configuration combined with other filters, and a paper housing 52 that is removably attached to the HVAC unit while maintaining the shape of the HVAC filter base material 51. By using the filter of the present invention, the indicator part is less likely to discolor with use, making it suitable as an HVAC filter. When the HVAC filter base material 51 has a multi-layer configuration, the filter on the side into which the air flows is sometimes called the pre-filter layer, and the filter on the side of the object is sometimes called the main filter layer. Generally, the pre-filter layer is often configured at a relatively low density to improve shape retention while collecting coarse dust, and the main filter layer is often configured at a relatively high density to collect relatively fine particles. The filter according to the present invention can be applied to either the pre-filter layer or the main filter layer, or both, but it is convenient to apply it to the pre-filter layer, where the indicator part is easily visible and does not require a special configuration.

[0075] Furthermore, in the above embodiment, there are no limitations on the method of manufacturing the nonwoven fabric, and nonwoven fabrics manufactured by known methods such as thermal bonding, chemical bonding, or needle punching can be used. Multiple bonding methods may also be used in combination. For example, thermal bonding and needle punching can be used in combination. In this way, the thickness of the filter body can be adjusted by the needle punching method to reduce the thickness of the nonwoven fabric manufactured by thermal bonding, making it possible to manufacture a filter suitable for the installation location and the conditions of the object.

[0076] Furthermore, in the above embodiment, the filter body is formed of a nonwoven fabric and a resin film, but other components such as an adhesive layer and a hook-and-loop fastener may be additionally provided on the filter body. For example, when the filter body is configured such that an adhesive layer is provided on the surface attached to an object, and a release sheet is further provided on the adhesive layer, the release sheet can be peeled off and attached to the object like a sticker during installation, and replacement to the object is facilitated even after use.

[0077] Furthermore, in the above embodiment, transfer by hot pressing is performed in the indicator portion forming step, but the resin film may be laminated on the nonwoven fabric surface by other methods. For example, a preformed resin film may be superimposed on the nonwoven fabric surface, melted by direct hot pressing, and then laminated.

[0078] Hereinafter, the present invention will be specifically described based on examples. Note that the embodiments of the present invention are not limited to the examples.

[0079] Specimens of examples and comparative examples of the present invention were prepared, and for these specimens, b-value measurement and calculation for obtaining Δb, and a visibility test for evaluating the visibility of the indicator portion when unused and after use were performed.

[0080] (Preparation of Specimen) In Example 1, the nonwoven fabric produced by a chemical bonding method has a mass per unit area of 43.5 g / m ２ of polyester fibers bound with 16.5 g / m ２ of acrylic binder resin, and a filter body with a basis weight of 60 g / m ２ was prepared. The dimensions of the filter body were 350 mm in the transverse direction and 600 mm in the longitudinal direction.

[0081] As a method for measuring basis weight, three nonwoven fabric pieces cut into 100 mm × 100 mm test specimens were collected, the mass (g) of each was measured with an electronic balance, and the average value of the three pieces was calculated. The basis weight per sheet was obtained by dividing this average value by the area of the test specimen (100 mm × 100 mm = 0.01 m ２ ) to obtain the basis weight per sheet.

[0082] In the indicator portion forming step, the above-mentioned transfer by hot pressing (transfer method) was performed.

[0083] Specifically, first, a resin ink was prepared in which, assuming the total weight of the resin ink is 100%, the synthetic resin portion contains 5% by weight of polyvinyl acetate resin, 9% by weight of polyvinyl butyral resin, and 6% by weight of acrylic resin, and the solvent portion contains 30% by weight of toluene solvent, 30% by weight of methyl ethyl ketone solvent, and 20% by weight of isopropyl alcohol solvent.

[0084] Next, a silicone PET film for release purposes is prepared, with the entire surface of the PET film silicone printed. The resin ink described above is then applied to the surface of the release film at a dry application rate of 3 g / m². ２ The image was printed and a transfer film was prepared.

[0085] The resin side of the transfer film was placed on the surface of the filter body, and the resin film was transferred to the filter body by heating and pressing at a pressure of 0.6 MPa, 100°C, and 0.5 seconds. A resin film with a thickness of 3.0 μm and a square shape of 23 mm on each side was then laminated on the surface of the filter body to form the indicator section.

[0086] In Example 2, the nonwoven fabric was manufactured by the chemical bonding method and had a density of 52.5 g / m². ２ Polyester fiber at 17.5 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 70 g / m². ２ This was used as the filter body.

[0087] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 1% by weight of polyvinyl acetate resin, 1% by weight of polyvinyl butyral resin, and 18% by weight of acrylic resin.

[0088] Other configurations and conditions were the same as in Example 1.

[0089] In Example 3, the nonwoven fabric was manufactured by the chemical bonding method and had a density of 30 g / m². ２ Polyester fiber at 10 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 40 g / m². ２This was used as the filter body.

[0090] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 2% by weight of polyvinyl acetate resin and 18% by weight of polyvinyl butyral resin.

[0091] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) should be 1.5 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 1.5 μm.

[0092] Other configurations and conditions were the same as in Example 1.

[0093] In Example 4, the nonwoven fabric was manufactured by the chemical bonding method and had a density of 52.5 g / m². ２ Polyester fiber at 17.5 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 70 g / m². ２ This was used as the filter body.

[0094] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 18% by weight of polyvinyl acetate resin and 2% by weight of polyvinyl butyral resin.

[0095] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) should be 1.5 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 1.5 μm.

[0096] Other configurations and conditions were the same as in Example 1.

[0097] In Example 5, the nonwoven fabric was manufactured by the chemical bonding method and had a density of 22.5 g / m². ２ Polyester fiber at 7.5 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 30 g / m². ２ This was used as the filter body.

[0098] Furthermore, assuming the entire resin ink is 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 10% by weight of polyethylene resin and 10% by weight of acrylic resin, and the composition of the solvent portion was assumed to be 30% by weight of toluene solvent and 50% by weight of xylene solvent.

[0099] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) is 2.0 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 2.0 μm.

[0100] Furthermore, the heating and pressing conditions for the transfer process were set to a pressure of 0.6 MPa, a temperature of 95°C, and a duration of 0.5 seconds.

[0101] Other configurations and conditions were the same as in Example 1.

[0102] In Example 6, the nonwoven fabric was manufactured by the chemical bonding method and had a density of 26.25 g / m². ２ Polyester fiber at 8.75 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 35 g / m². ２ This was used as the filter body.

[0103] Furthermore, the resin used for the resin film was replaced with 100% by weight polyethylene resin (single-layer) instead of resin ink. The polyethylene resin used had a specific gravity of 0.95 g / cm³. ３ The material has a softening point of 115°C and a melt flow index of 50 g / 10 m. The melt flow index was calculated according to JIS K 7210 A method, by cutting the extruded resin three times at specified time intervals and deriving the average mass from the cuts.

[0104] Furthermore, a transfer film was prepared by extruding the above-mentioned polyethylene resin onto a release film (release paper) with a silicone print applied to the surface of a paper substrate using a T-die extrusion melt lamination method.

[0105] Furthermore, the heating and pressing conditions for the transfer process were set to a pressure of 0.6 MPa, 115°C, and 0.5 seconds.

[0106] Furthermore, the thickness of the resin film constituting the indicator section was set to 25 μm.

[0107] Other configurations and conditions were the same as in Example 1.

[0108] Comparative Example 1 is a nonwoven fabric manufactured by the chemical bonding method, with a density of 26.25 g / m². ２ Polyester fiber at 8.75 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 35 g / m². ２ This was used as the filter body.

[0109] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 20% by weight of polyurethane resin.

[0110] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) is 2.0 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 2.0 μm.

[0111] Furthermore, the heating and pressing conditions for the transfer process were set to a pressure of 0.6 MPa, a temperature of 95°C, and a duration of 0.5 seconds.

[0112] Other configurations and conditions were the same as in Example 1.

[0113] Comparative Example 2 is a nonwoven fabric manufactured by the chemical bonding method, with a density of 30 g / m². ２ Polyester fiber at 10 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 40 g / m². ２ This was used as the filter body.

[0114] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 2% by weight of polyurethane resin and 18% by weight of acrylic resin.

[0115] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) should be 1.5 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 1.5 μm.

[0116] Furthermore, the heating and pressing conditions for the transfer process were set to a pressure of 0.6 MPa, a temperature of 95°C, and a duration of 0.5 seconds.

[0117] Other configurations and conditions were the same as in Example 1.

[0118] Comparative Example 3 is a nonwoven fabric manufactured by the chemical bonding method, with a density of 52.5 g / m². ２ Polyester fiber at 17.5 g / m ２ Using a material bonded with an acrylic binder resin, the basis weight is 70 g / m². ２ This was used as the filter body.

[0119] Furthermore, when the entire resin ink is considered to be 100% by weight, the composition of the synthetic resin portion contained in the resin ink was assumed to be 20% by weight of polyvinyl chloride resin.

[0120] Furthermore, the amount of resin ink applied to the release film (amount applied after drying) should be 1.5 g / m². ２ Furthermore, the thickness of the resin film constituting the indicator section was set to 1.5 μm.

[0121] Furthermore, the heating and pressing conditions for the transfer process were set to a pressure of 0.6 MPa, a temperature of 95°C, and a duration of 0.5 seconds.

[0122] Other configurations and conditions were the same as in Example 1.

[0123] (Measurement and calculation of b-value) In accordance with JIS Z 8722, the Lab values ​​of the test specimens (Examples 1 to 6 and Comparative Examples 1 to 3) were measured using a spectrophotometer (model CM-5) manufactured by Konica Minolta, Inc.

[0124] In the spectrophotometer, the measurement conditions were set to reflectance mode as the measurement type and a measurement diameter of Φ11 mm. A target mask (CM-A-196 manufactured by Konica Minolta, Inc.) with the same measurement diameter of Φ11 mm was installed.

[0125] A zero calibration box (model number CM-A124) manufactured by Konica Minolta, Inc. was placed in the measurement port of the CM-5, and zero calibration was performed. Subsequently, white calibration was performed.

[0126] For the specular reflection processing settings, SCI mode was selected.

[0127] For the observation conditions, the color system L*a*b* was selected, the observation field of view was 10°, and the observation light source was D65.

[0128] After completing the above condition settings, the Lab value of the test specimen was measured.

[0129] To measure the reference color (ventilation area), the sample was prepared so that the dimensions of the test filter were 30 mm wide x 60 mm long.

[0130] To measure the color (indicator area), the sample was prepared so that the indicator area was centered, with dimensions of 30 mm wide x 60 mm high.

[0131] To measure the Lab value, the above sample was placed in a spectrophotometer, and a black stainless steel plate measuring 90 mm on each side and weighing 141.6 g was placed on top of the sample, and the reference color was measured.

[0132] Next, the indicator section was placed so that the surface forming the resin film covered the measurement opening, and a sample holder made of black stainless steel weighing 141.6 g was placed on top of it, and the measurement color was taken.

[0133] Then, the difference Δb(b'-b) was calculated from the b value (b') of the reference color (ventilated area) and the b value (b) of the indicator area.

[0134] Three measurements were taken, and the average of each Δb value was used as the filter's Δb.

[0135] (Visibility of the indicator part: Range hood) Using nine types of filters from Examples 1 to 6 and Comparative Examples 1 to 3, the filters were attached to the metal filter surface of a range hood with magnets so that the side of the indicator part of the filter body with the resin film facing the metal filter surface, and the following tests were conducted. A deep-type range hood (model name: BDR-3HL-601ABK) manufactured by Fuji Kogyo Co., Ltd. was used as the range hood, and suction was performed in strong operation mode. A metal slot filter (model number: RCSF10-3421) manufactured by Fuji Kogyo Co., Ltd. was used as the metal filter. Magnets were placed one at each of the four corners of the filter for attachment.

[0136] 1. Visual evaluation of the indicator section when not in use: The filter was visually inspected to confirm whether the indicator section was visible or not. If the presence of the indicator section was not apparent, it was evaluated as "○" (suitable); if the presence of the indicator section was apparent, it was evaluated as "×" (unsuitable).

[0137] 2. Visual evaluation of the indicator after use: A frying pan (outer diameter 26 cm, depth 5 cm) placed on a stove was preheated. With the surface temperature at 260°C, 1.35 cc of water and 1.38 cc of oil (manufactured by Nisshin Oillio, product name: Nisshin Canola Oil) were dripped from above the frying pan. This dripping was continued for 1 hour, generating oil fumes for 1 hour.

[0138] After one hour, the stove was turned off to stop the generation of oil fumes, and the filter attached to the range hood was visually inspected. If the indicator part could be visually confirmed by a difference in discoloration on a part of the filter body, it was evaluated as "○" (suitable). If there was no difference in discoloration due to the collection of oil fumes and the indicator part could not be visually confirmed, it was evaluated as "×" (unsuitable).

[0139] The results are shown in Table 1 below.

[0140] Referring to Table 1, Comparative Examples 1 and 2, and Comparative Example 3, where Δb exceeded +1, received poor evaluations because the indicator part was visible when not in use. In contrast, Examples 1 to 6, where Δb was between -1 and +1, were suitable because the indicator part was not visible when not in use, and were visible after use, resulting in good results.

[0141] Furthermore, in Comparative Example 1 and Comparative Example 2, the visual evaluation of the indicator part after use was also unsuitable.

[0142] (Visibility of indicator section: HVAC) Using nine types of filters from Examples 1 to 6 and Comparative Examples 1 to 3, HVAC filters with the same shape as HVAC filter 5 (see Figure 4, etc.) were manufactured. In manufacturing the HVAC filters, a composite filter was prepared as the HVAC filter substrate by laminating a pre-filter layer and a main filter layer. For the manufacture of the composite filter, the nine types of filters from the aforementioned examples and comparative examples were prepared as the pre-filter layer, and the main filter layer was manufactured using the meltblown method with a basis weight of 20 g / m². ２ We prepared a meltblown nonwoven fabric by manufacturing a polypropylene nonwoven fabric and then performing electrostatic treatment using corona discharge.

[0143] Next, a hot-melt polyurethane resin adhesive was sprayed onto one side of each pre-filter layer and bonded to the main filter layer to prepare a two-layer HVAC filter substrate. In addition, a wire mesh was bonded to the surface of the main filter layer (meltblown nonwoven fabric) as a reinforcing layer.

[0144] Next, a pleating process was carried out to create an HVAC filter substrate with a pleat height of 1 inch (2.54 cm) and a pleat pitch of 0.4 inches (1.016 cm).

[0145] Finally, the HVAC filter substrate was set in a paper casing to create an HVAC filter measuring 16 inches (40.64 cm) x 16 inches (40.64 cm) x 1 inch (2.54 cm) in height.

[0146] The HVAC filter prepared in this manner was attached to the HVAC unit, and the following tests were conducted.

[0147] 1. Visibility of the indicator before use: The pre-filter layer side of the HVAC filter was visually inspected to confirm the presence of the indicator. If the presence of the indicator was not visible, it was evaluated as "○" (suitable); if the presence of the indicator was visible, it was evaluated as "×" (unsuitable).

[0148] 2. Visibility of the indicator after use After installing the HVAC filter into the HVAC unit, the HVAC system was operated under normal operating conditions for one month. Then, the HVAC system was stopped, and the pre-filter layer of the HVAC filter attached to the HVAC unit was visually inspected. If the indicator could be visually confirmed by a difference in discoloration on a part of the pre-filter layer, it was evaluated as "○" (suitable). If there was no difference in discoloration due to dust, etc., and the indicator could not be visually confirmed, it was evaluated as "×" (unsuitable).

[0149] The results are shown in Table 1 above.

[0150] Referring again to Table 1, it was confirmed that, similar to the case when installed in a range hood, when used as an HVAC filter, Comparative Examples 1 and 2, and Comparative Example 3, where Δb exceeded +1, were poorly evaluated because the indicator part was visible when not in use. In contrast, Examples 1 to 6, where Δb was between -1 and +1, were suitable because the indicator part was not visible when not in use, and were good results because the indicator part was visible after use.

[0151] Furthermore, in Comparative Example 1 and Comparative Example 2, the visual evaluation of the indicator part after use was also unsuitable.

[0152] As described above, the filter according to the present invention is suitable for preventing dirt buildup in, for example, range hoods, air conditioners, air purifiers, ventilation fans and vents, HVAC systems, and the like.

Claims

1. A filter (1) that is replaceably attached to an object and comprises a filter body (11, 21) made of nonwoven fabric, wherein the filter body comprises an indicator section (13, 23) formed by laminating a resin film on the surface of the nonwoven fabric and indicating or suggesting a replacement time as it is used, and a ventilation section (12) other than the indicator section, wherein in the Lab system, the difference Δb(b'-b) between the b value (b) in the indicator section when not in use and the b value (b') in the ventilation section is between -1 and +1.

2. The filter according to claim 1, wherein the resin film is composed of one type of resin or a mixture of multiple types of resins selected from the group consisting of polyethylene resin, polypropylene resin, polyester resin, polyvinyl butyral resin, acrylic resin, ABS resin, and ethylene vinyl acetate copolymer resin.

3. The basis weight of the filter body is 30 g / m². ２ More than 200g / m ２ The filter according to claim 1 or claim 2, which is as follows:

4. The filter body is flame-retardant, as described in claim 1 or claim 2.

5. The filter according to claim 1 or claim 2, wherein the object is a range hood or ventilation fan.

6. The filter according to claim 1 or claim 2, wherein the object is an HVAC system.

7. A method for manufacturing a filter that can be replaced and attached to an object, comprising: a preparation step of preparing a filter body made of nonwoven fabric; and an indicator part formation step of laminating a resin film on a part of the surface of the filter body to form an indicator part that displays or suggests the time for replacement as it is used, wherein in the Lab system, the difference Δb(b'-b) between the b value (b) in the indicator part and the b value (b') in the ventilation part which is a part other than the indicator part is between -1 and +1.

8. The method for manufacturing a filter according to claim 7, wherein in the indicator portion forming step, the resin film is laminated by transferring a transfer film, which is made by applying resin ink to the surface of a release film, to a part of the surface of the filter body.

9. The method for manufacturing a filter according to claim 8, wherein in the indicator portion forming step, the transfer film is transferred to a part of the surface of the filter body by heating and pressing.

10. The method for manufacturing a filter according to any one of claims 7 to 9, wherein the resin film is composed of one type of resin or a mixture of multiple types of resins selected from the group consisting of polyethylene resin, polypropylene resin, polyester resin, polyvinyl butyral resin, acrylic resin, ABS resin, and ethylene vinyl acetate copolymer resin.

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