JP2024051263A - Breathable sheet, and printing device and conveying device equipped with breathable sheet - Google Patents

Abstract

To provide a breathable sheet that can be firmly fixed to the suction stage of a vacuum suction device used when printing on the surface of a non-breathable substrate such as a film that is suction-fixed, or to the suction part of a vacuum transport device used when a non-breathable substrate is suction-fixed and vacuum-transported.
[Solution] The breathable sheet of the present invention uses a vacuum suction device equipped with an adsorption stage capable of adsorbing ferromagnetic materials by magnetic force, and a vacuum conveying device equipped with a suction part capable of adsorbing ferromagnetic materials by magnetic force, and is a breathable sheet formed by laminating a nonwoven fabric layer in contact with a non-breathable substrate and a support layer in contact with the adsorption stage or suction part, the support layer containing a ferromagnetic material.
[Selected Figure] Figure 1

Description

The present invention relates to a breathable sheet that is placed between the suction stage of a vacuum suction device and a non-breathable substrate, such as a film, when printing on the surface of the substrate, and the sheet is also related to a printing device equipped with the breathable sheet.

The invention also relates to a breathable sheet that is placed between the suction part of a vacuum transport device and a non-breathable substrate when the non-breathable substrate is suctioned and fixed by the suction part of the vacuum transport device and transported by vacuum, and a transport device equipped with the breathable sheet.

As electrical devices become smaller, the development of small, lightweight, and thin electronic components, such as integrated circuits, wiring materials, and electronic substrates (hereinafter collectively referred to as electronic components), is progressing. In recent years, printed electronics has been attracting attention as a technology that can meet this demand.

Printed electronics is a technical field in which various inks containing conductive or semiconducting components (hereinafter, the various inks used in printed electronics may be simply referred to as inks) are printed on the surface of a non-breathable substrate such as a film, and wiring and various electronic components are formed on the surface of the non-breathable substrate.

By using printed electronics, for example, wiring and various electronic components can be formed on the surface of a light, thin, non-breathable substrate such as a film, or a flexible, non-breathable substrate, making it possible to provide small, lightweight, or flexible electrical devices.

In printed electronics, printing is performed on the surface of a non-breathable substrate that is fixed by suction to the suction stage (particularly a flat suction stage) of a vacuum suction device so that fine, clear printing can be achieved when forming electronic components. In this case, it is required that the unevenness of the surface of the non-breathable substrate that is fixed by suction is very small.

To deal with this, a breathable sheet is placed between the suction stage of the vacuum suction device and the non-breathable substrate to distribute the suction pressure that is generated vertically from the suction port of the suction stage when the non-breathable substrate is suction-fixed, making it possible to greatly reduce the unevenness of the surface of the non-breathable substrate that is being suction-fixed, and to achieve clear printing on the surface of the non-breathable substrate.

For example, WO 2016/021239 (Patent Document 1) discloses an example of such a breathable sheet, which is characterized by being composed of a laminate of a nonwoven fabric layer in contact with a non-breathable substrate and a support layer made of a woven or knitted fabric in contact with an adsorption stage.

In addition to printed electronics, the above-mentioned breathable sheet can be used as a breathable sheet to be interposed between a vacuum transport device and a non-breathable substrate when the non-breathable substrate is suction-fixed and vacuum-transported by the suction part of the vacuum transport device. As in the case of use for printed electronics, the breathable sheet used in the vacuum transport device is required to be able to disperse the suction pressure that is generated vertically from the suction port of the suction part when the non-breathable substrate is suction-fixed to the suction part of the vacuum transport device, thereby preventing deformation of the suction-fixed non-breathable substrate.

International Publication No. 2016/021239

However, while the breathable sheet of Patent Document 1 is interposed between the vacuum suction device and the non-breathable substrate, and the non-breathable substrate is suction-fixed to the suction stage of the vacuum suction device, the breathable sheet placed on the suction stage sometimes shifts. As a result, the non-breathable substrate cannot be sufficiently fixed on the suction stage, and the non-breathable substrate shifts during printing, making it impossible to perform fine, clear printing on the surface of the non-breathable substrate. Furthermore, since printing cannot be performed on the surface of the non-breathable substrate with good reproducibility, it is sometimes impossible to provide wiring and various electronic components with high reproducibility.

In addition, while the breathable sheet of Patent Document 1 is interposed between the vacuum transport device and the non-breathable substrate and the non-breathable substrate is suctioned and fixed by the suction part of the vacuum transport device, the breathable sheet in contact with the suction part may shift. As a result, the non-breathable substrate may not be sufficiently fixed to the suction part, and stable vacuum transport may not be possible.

The present invention aims to solve the above-mentioned problems and provide a breathable sheet that can be firmly fixed to the suction stage of a vacuum suction device or to the suction part of a vacuum transport device.

The invention according to claim 1 of the present invention is "a breathable sheet for use between the suction stage of a vacuum suction device and a non-breathable substrate when printing is performed on the surface of the non-breathable substrate fixed by suction on the suction stage, or between the suction part of a vacuum transport device and the non-breathable substrate when the non-breathable substrate is fixed by suction and transported by vacuum, the breathable sheet being made by laminating a nonwoven fabric layer in contact with the non-breathable substrate and a support layer made of a woven or knitted fabric in contact with the suction stage or the suction part, the support layer including a ferromagnetic material."

The invention according to claim 2 of the present invention is "a printing device used for printing on the surface of a non-breathable substrate, comprising the vacuum suction device having an adsorption stage capable of adsorbing a ferromagnetic material by magnetic force, and the breathable sheet according to claim 1."

The invention according to claim 3 of the present invention is "a conveying device used to convey non-breathable substrates, comprising the vacuum conveying device having a suction portion capable of attracting ferromagnetic material by magnetic force, and the breathable sheet according to claim 1."

After much investigation, the inventors have found that the above-mentioned problems can be solved by using a vacuum suction device equipped with an adsorption stage capable of magnetically adsorbing ferromagnetic material, and a vacuum transport device equipped with a suction portion capable of magnetically adsorbing ferromagnetic material, and by using a breathable sheet in which a nonwoven fabric layer in contact with a non-breathable substrate and a support layer in contact with the adsorption stage or suction portion are laminated together, the support layer containing a ferromagnetic material that is attracted to a magnet or electromagnet.

In other words, they found that the breathable sheet can be firmly fixed to the adsorption stage and adsorption part by the suction force exerted by the adsorption stage and adsorption part, as well as by the magnetic force exerted between the adsorption stage and adsorption part and the support layer of the breathable sheet that is in direct contact with them.

As a result, the breathable sheet placed on the suction stage is prevented from shifting, allowing fine, clear printing to be performed on the surface of the non-breathable substrate. Furthermore, since printing can be performed with good reproducibility on the surface of the non-breathable substrate, it is possible to provide wiring and various electronic components with high reproducibility.

In addition, when the non-breathable substrate is suctioned and fixed by the suction part of the vacuum transport device and transported by vacuum, the breathable sheet in contact with the suction part is prevented from shifting, and the non-breathable substrate can be sufficiently fixed to the suction part and stably transported by vacuum.

FIG. 2 is a schematic cross-sectional view showing a state in which printing is carried out on a non-breathable substrate using the breathable sheet of the present invention.

As with conventionally known printed electronics technology, the breathable sheet of the present invention is placed on a suction stage built into a vacuum suction device, a non-breathable substrate made of a film or the like is placed in contact with the sheet, and printing is performed by operating the device.

Hereinafter, with reference to FIG. 1, which is a schematic cross-sectional view of the breathable sheet of the present invention when used, a non-breathable substrate is sucked and fixed to the suction stage of the vacuum suction device with the breathable sheet interposed between the suction stage of the vacuum suction device and the non-breathable substrate, and printing is performed on the surface of the non-breathable substrate. The breathable sheet (3) of the present invention includes at least one nonwoven fabric layer (3b) and at least one support layer (3a), and may further include other breathable members as desired, and is configured by laminating them. The breathable sheet (3) is used with the support layer (3a) in contact with the suction stage (1) provided with the suction port (2), and with the non-breathable substrate (4) placed in contact with the nonwoven fabric layer (3b), a pump or compressor (not shown) connected to the vacuum suction device is operated to suck air from the suction port (2), and with the breathable sheet (3) interposed between the suction stage (1) of the vacuum suction device and the non-breathable substrate (4), the non-breathable substrate (4) is sucked and fixed to the suction stage (1) of the vacuum suction device. In this case, other breathable materials may be interposed between the layers of the breathable sheet (3), but it is necessary that the support layer (3a) is present on the suction stage (1) side of the nonwoven fabric layer (3b). In other words, as an effect of the breathable sheet (3) of the present invention, when air is sucked between the non-breathable substrate (4) and the suction stage (1) through the suction port (2), the support layer (3a) of the breathable sheet (3) interposed between them first relieves the localization of the suction force due to the pattern of the suction port (2). Next, the suction force on the device side penetrating the support layer (3a) is further dispersed through the nonwoven fabric layer (3b), attracting the non-breathable substrate (4), which is the direct object of the suction force, to the suction stage (1), and printing by the ink application member (5) can be performed with high precision while maintaining the flatness of the non-breathable substrate (4). During this time, the influence of the device conditions such as the spacing of the suction port pattern of the vacuum suction device is further mitigated by making the fiber diameter of the fibers constituting the nonwoven fabric layer (3b) smaller than the mesh size (not shown) of the woven or knitted fabric. Furthermore, the "non-breathable substrate" referred to in this application means that, even in the case of forming multi-layer wiring (via holes, contact holes) on the front and back of a film with extremely fine openings, as long as it can be fixed to the vacuum suction device, it is possible to form a clear ink pattern.

The woven or knitted fabric that constitutes the support layer (3a) of the breathable sheet also has breathability in the thickness direction and in the direction perpendicular to it. This allows the suction force from the suction stage (1) and the like to be dispersed in multiple directions within the volume occupied by the support layer (3a).

Furthermore, the support layer (3a) constituting the breathable sheet (3) of the present invention contains a ferromagnetic material. As a result, when the breathable sheet (3) is placed so that the support layer (3a) of the breathable sheet contacts the adsorption stage (1) using a vacuum adsorption device equipped with an adsorption stage (1) capable of adsorbing a ferromagnetic material by magnetic force, and the breathable sheet (3) is interposed between the adsorption stage (1) and the non-breathable substrate (4) and adsorbed and fixed, the adsorption stage (1) can firmly fix the breathable sheet (3) to the adsorption stage (1) by the magnetic force exerted between the adsorption stage (1) and the support layer (3a) of the breathable sheet (3) that is in direct contact with them, in addition to the suction force exerted by the adsorption stage (1). As a result, the breathable sheet (3) placed on the adsorption stage (1) is prevented from shifting, and fine and clear printing can be applied to the surface of the non-breathable substrate (4). Furthermore, since printing can be performed with good reproducibility on the surface of the non-breathable substrate (4), it is possible to provide wiring and various electronic components with high reproducibility.

In FIG. 1, the case where the shape of the suction stage (1) is flat is described, but as long as the non-breathable substrate (4) can be suction-fixed to the suction stage (1), the shape of the suction stage (1) is not particularly limited, and may be curved.

The suction stage (1), which can attract ferromagnetic material by magnetic force, can have, for example, a magnet or electromagnet inside the suction stage (1), or a magnet or electromagnet on the back side where the suction stage (1) contacts the breathable sheet (3).

Next, we will explain how the non-breathable substrate is vacuum-transported by the vacuum transport device while a breathable sheet is interposed between the vacuum transport device and the non-breathable substrate (not shown).

The breathable sheet is used in a state where the support layer of the breathable sheet is in contact with a vacuum conveying device provided with a suction part, in the same manner as when the breathable sheet is interposed between the suction stage of the vacuum suction device and the non-breathable substrate and fixed to the suction stage of the vacuum suction device, and a pump or compressor connected to the suction part is operated with the non-breathable substrate in contact with the nonwoven fabric layer, and air is sucked in from the suction port of the suction part, so that the non-breathable substrate is sucked in and fixed to the suction part with the breathable sheet interposed between the vacuum conveying device, the suction part, and the non-breathable substrate. In this case, other breathable materials may be interposed between the layers of the breathable sheet, but it is necessary that there is a support layer on the suction part side of the nonwoven fabric layer. In other words, the effect of the breathable sheet of the present invention is that when air is sucked in between the non-breathable substrate and the vacuum conveying device from the suction port of the suction part, the support layer of the breathable sheet interposed between them first alleviates the localization of the suction force due to the suction port pattern. Next, the suction force of the device that penetrates the support layer is further dispersed through the nonwoven fabric layer, attracting the non-breathable substrate, which is the direct target of the suction force, to the vacuum transport device, and the non-breathable substrate can be vacuum-fixed and transported by the vacuum transport device.

Furthermore, the support layer constituting the breathable sheet of the present invention contains a ferromagnetic material as described above. As a result, when a vacuum transport device equipped with a suction part capable of magnetically attracting a ferromagnetic material is used to place the breathable sheet so that the support layer of the breathable sheet is in contact with the suction part, and the breathable sheet is interposed between the suction part and the non-breathable substrate to suction-fix the non-breathable substrate, the breathable sheet can be firmly fixed to the suction part by the suction force exerted by the suction part, as well as the magnetic force exerted between the suction part and the support layer of the breathable sheet that is in direct contact with them. As a result, when the non-breathable substrate is suction-fixed by the suction part of the vacuum transport device and vacuum-transported, the breathable sheet in contact with the suction part is prevented from shifting, and the non-breathable substrate can be sufficiently fixed to the suction part and stably vacuum-transported.

The suction part of the vacuum transport device that can attract ferromagnetic materials by magnetic force can have, for example, a magnet or electromagnet inside the suction part, or a magnet or electromagnet on the back side where the suction part of the vacuum transport device comes into contact with the breathable sheet.

The woven or knitted fabric that forms the support layer (3a) contains a ferromagnetic material. Various metals can be selected as the ferromagnetic material that can be contained in the support (3a), but a ferromagnetic material made of stainless steel (SUS) is most preferable because it can maintain a relatively robust structure when suction force is applied and has excellent rust resistance and rigidity. That is, in printed electronics and vacuum transport, the diameter of the suction port of the suction stage or suction part is reduced in order to print the pattern to be printed clearly, and deformation of the non-breathable substrate directly above the suction port is suppressed. However, when the diameter of the suction port is reduced, the processing cost of the suction stage or suction part itself increases, and the suction efficiency of the non-breathable substrate tends to decrease. The breathable sheet to which the present invention is applied can distribute the suction force of the suction stage or suction part in multiple directions within the volume occupied by the support layer, and the large surface area of the nonwoven fabric layer can suppress the decrease in suction force. Furthermore, since it can provide a flat surface for the non-breathable substrate, it can be easily installed on the suction stage or suction part of a general vacuum suction device, thereby significantly reducing costs and improving work efficiency.

The above-mentioned support layer (3a) may be made of a plain weave or twill weave, or a knitted fabric such as a stockinette. It is preferable to select a plain weave fabric, which has a simple structure, relatively small surface irregularities, and is less stretchable and less likely to deform. In particular, in the case of a support layer (3a) made of a woven fabric, the mesh size of the support layer (3a) is preferably 0.030 to 0.270 mm, more preferably 0.060 to 0.250 mm, and even more preferably 0.100 to 0.230 mm. By making the mesh size of the support layer (3a) as small as 0.270 mm or less, the bending rigidity of the entire breathable sheet (3) can be ensured, and a flat surface can be provided for the non-breathable substrate (4) fixed by suction. In addition, by making the mesh size of the support layer (3a) as large as 0.030 mm or more, the breathability of the support layer (3a) is sufficient, and the non-breathable substrate (4) can be fixed sufficiently.

The "mesh opening" referred to here is a value equivalent to the length of one side of the mesh-like opening formed by the wires or threads, and can usually be calculated using the following value based on the number of meshes and the wire diameter d in millimeters. This formula is a widely known calculation method, and it has been confirmed that there is an extremely high correlation with the results of observation under a microscope.

Mesh size = (25.4/number of meshes) - wire diameter d
In addition, when the mesh size of the woven fabric varies depending on the yarn arrangement direction, the area of the opening is calculated from the mesh size in one arrangement direction and the mesh size in the other arrangement direction intersecting the aforementioned arrangement direction. Next, the length of one side of the opening is calculated from the area of the opening assuming that the opening is a square, and this length of one side of the opening is regarded as the mesh size of the support layer (3a). In addition, for woven fabrics that do not have mesh sizes, the size of the mesh size is regarded as 0 mm.

In the case of a support layer (3a) made of knitted fabric, first, the stitches in a square area of 1 cm x 1 cm from the knitted fabric are observed, and the average area of each stitch in the square area is calculated. Next, the length of one side of the stitch is calculated from the average area of each stitch, assuming that the stitch is a square. This length of one side of the stitch is set as the mesh opening of the support layer (3a), and it is preferable that it is within the range of the mesh opening of the support layer (3a) described above.

The various configurations of the support layer (3a) such as the basis weight before lamination, the thickness before lamination, and the porosity before lamination are preferably adjusted as appropriate, and the basis weight of the support layer (3a) before lamination is preferably 50 g/m ² or more, more preferably 200 g/m ² or more, and even more preferably 400 g/m ² or more. The upper limit of the basis weight of the support layer (3a) before lamination is adjusted as appropriate, but it is practical to set it to 1000 g/m ² or less. Note that "basis weight" is the mass per 1 m ² of the main surface, which is the widest surface, and "basis weight of the support layer (3a) before lamination" is the basis weight of the woven or knitted fabric before lamination that constitutes the support layer (3a).

The thickness of the support layer (3a) before lamination is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. The upper limit of the thickness of the support layer (3a) before lamination is adjusted as appropriate, but it is practical to set it to 300 μm or less. In the present invention, the "thickness" is the average value of values measured at 15 points per ^m2 under a load of 0.054 N/ ^mm2 , and the "thickness of the support layer (3a) before lamination" is the value obtained by measuring the thickness of the woven or knitted fabric constituting the support layer (3a) before lamination using the above-mentioned method.

Furthermore, the porosity of the support layer (3a) before lamination is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more, because a support layer (3a) with a high porosity can sufficiently suck the non-breathable substrate (4) when the non-breathable substrate (4) is suction-fixed to the adsorption stage (1) or the suction part. The upper limit of the porosity is less than 100%, and the upper limit of the porosity of the support layer (3a) before lamination is preferably 90% or less, so that the support layer (3a) is unlikely to deform due to the suction pressure when the non-breathable substrate (4) is suction-fixed to the adsorption stage (1) or the suction part, and can be a breathable sheet (3) with little unevenness on the surface. The porosity (unit: %) of the support layer (3a) before lamination can be calculated from the basis weight (unit: g/ ^m2 ) of the support layer (3a) before lamination, the thickness (unit: μm) of the support layer (3a) before lamination, and the density (unit: g/ ^cm3 ) of the constituent material of the support layer (3a) using the following formula.
Porosity = [1 - (basis weight / (thickness x density))] x 100

Next, the nonwoven fabric layer (3b) included in the breathable sheet (3) will be described. The breathable sheet (3) is used in a state where the support layer (3a) is in contact with the adsorption stage (1) or suction part provided with the suction port (2), and the non-breathable substrate (4) is placed in contact with the nonwoven fabric layer (3b). When a pump or compressor (not shown) connected to the adsorption stage (1) or suction part is operated and air is sucked in from the suction port (2) to fix the non-breathable substrate (4), the nonwoven fabric layer (3b) can further disperse and relieve the suction force due to the pattern of the suction port (2) that has been relieved by the support layer (3a) made of woven or knitted fabric. The effect of dispersing and relieving the suction force by the nonwoven fabric layer (3b) can be realized because the arrangement of fibers in the nonwoven fabric constituting the nonwoven fabric layer (3b) is not regular compared to woven or knitted fabrics in which the fibers are regularly arranged.

The composition of the fibers constituting the nonwoven fabric layer (3b) is not particularly limited, but specific examples include polyolefin resins (polyethylene, polypropylene, polymethylpentene, polyolefin resins in which part of the hydrocarbon is replaced with a cyano group or a halogen such as fluorine or chlorine, etc.), styrene resins, polyether resins (polyether ether ketone, polyacetal, phenolic resins, melamine resins, urea resins, epoxy resins, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polyester resins, unsaturated polyester resins, etc.), polyimide resins, polyamide-imide resins, poly It is preferable to use fibers made of synthetic resins such as amide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (polysulfone, polyethersulfone, etc.), fluorine resins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.), vinylon resins (vinyl acetate, polyvinyl alcohol, etc.), and conductive polymers (polypyrrole, polyaniline, polyacetylene, polythiophene, etc.). These constituent fibers may be made of one or more types of resin components, and composite fibers generally called composite fibers, such as core-sheath type, sea-island type, side-by-side type, and orange type, can be used.

This nonwoven fabric layer (3b) can be a variety of nonwoven fabrics, such as dry nonwoven fabrics, wet nonwoven fabrics, and direct spun nonwoven fabrics (e.g., electrostatic spun nonwoven fabrics, spunbond nonwoven fabrics, and meltblown nonwoven fabrics). Of these nonwoven fabrics, direct spun nonwoven fabrics are preferred from the viewpoints of preventing dust generation from the breathable sheet (3) and preventing fluffing on the surface of the nonwoven fabric layer (3b) facing the non-breathable substrate (4).

In addition, by making the fiber diameter of the constituent fibers of the nonwoven fabric layer (3b) small, the number of fibers per unit area in the contact plane with the non-breathable substrate (4) increases for the same basis weight, improving the surface flatness of the nonwoven fabric layer. This makes it possible to fix the non-breathable substrate (4) more flatly when adsorbing and fixing the non-breathable substrate (4). For this reason, it is preferable that the fiber diameter of the nonwoven fabric layer (3b) is 10.5 μm or less, more preferably 1 μm or less. The breathable sheet of the present invention is not limited to the case where a single nonwoven fabric layer (3b) is provided, and when multiple nonwoven fabric layers (3b) are provided, it is preferable that the layer mainly composed of the constituent fibers having a fiber diameter of 10.5 μm or less described above is a component that directly contacts the non-breathable substrate (4). In this case, since the nonwoven fabric layer (3b) composed of relatively fine synthetic fibers tends to be easily charged between the non-breathable substrate (4) such as a film by suction of a vacuum device, etc., it is preferable to blend conductive fibers for the purpose of preventing static electricity into the nonwoven fabric layer (3b). Instead of blending the conductive fibers, various forms can be used, such as coating and adding a surfactant to the surface of the nonwoven fabric layer (3b). In this case, the final amount of surfactant applied to the nonwoven fabric layer (3b) can be designed as desired and appropriate depending on the type of surfactant used.

The various configurations of the nonwoven fabric layer (3b) such as the basis weight before lamination and the thickness before lamination are preferably adjusted as appropriate, and the basis weight of the nonwoven fabric layer (3b) before lamination is preferably 5 g/ ^m2 or more, more preferably 10 g/ ^m2 or more, and even more preferably 20 g/ ^m2 or more. The upper limit of the basis weight of the nonwoven fabric layer (3b) is adjusted as appropriate, but it is practical to set it to 200 g/ ^m2 or less. The "basis weight of the nonwoven fabric layer (3b) before lamination" refers to the basis weight of the nonwoven fabric constituting the nonwoven fabric layer (3b) before lamination.

The thickness of the nonwoven fabric layer (3b) before lamination is preferably 10 to 300 μm, more preferably 30 to 200 μm, and even more preferably 50 to 100 μm. Note that the "thickness of the nonwoven fabric layer (3b) before lamination" refers to the thickness of the nonwoven fabric that constitutes the nonwoven fabric layer (3b) before lamination.

In addition, the nonwoven fabric layer (3b) may be composed of only one type of fiber or two or more types of fibers, but it is preferable that the nonwoven fabric layer is composed of one type of fiber, since the constituent fibers of the nonwoven fabric layer are uniformly distributed and the unevenness of the breathable sheet surface is smaller.

When the nonwoven fabric layer (3b) and the support layer (3a) of the breathable sheet are integrated, or when the nonwoven fabric layer (3b) has multiple nonwoven fabrics, it is preferable to stack them and then integrate them by thermocompression bonding to improve the handleability of the breathable sheet. Also, instead of thermocompression bonding, an adhesive made of an organic resin can be applied between the layers, or a sheet-like object made of a low-melting organic resin can be sandwiched between the layers to bond them together.

The air permeability of the breathable sheet (3) of the present invention by the Frazier method is preferably 0.10 cm ³ /cm ² /s or more. When the air permeability of the breathable sheet (3) by the Frazier method is 0.10 cm ³ /cm ² /s or more, the non-breathable substrate (4) can be sufficiently fixed when the breathable sheet is interposed between the suction stage (1) or the suction part of the vacuum suction device and the non-breathable substrate (4) and the non-breathable substrate (4) is suctioned and fixed. In order to more stably fix the non-breathable substrate (4), the air permeability of the breathable sheet (3) by the Frazier method is more preferably 0.20 cm ³ /cm ² /s or more, and even more preferably 0.25 cm ³ /cm ² /s or more. The "air permeability by the Frazier method" refers to a value measured by the Frazier method specified in JIS L 1096.

The various components of the breathable sheet (3) of the present invention, such as basis weight, thickness, bulk density, etc., are preferably adjusted as appropriate, and the basis weight of the breathable sheet (3) is preferably 60 g/ ^m2 or more, more preferably 220 g/ ^m2 or more, and even more preferably 435 g/ ^m2 or more. The upper limit of the basis weight of the breathable sheet (3) is adjusted as appropriate, but it is practical to set it to 1000 g/ ^m2 or less.

The thickness of the breathable sheet (3) is preferably 600 μm or less, more preferably 450 μm or less, and even more preferably 350 μm or less, since a large thickness may cause poor handling during printing. On the other hand, if the thickness is too thin, the suction pressure of the suction stage (1) may not be sufficiently dispersed, and unevenness may occur on the surface of the non-breathable substrate (4), so the thickness is preferably 50 μm or more, more preferably 130 μm or more, and even more preferably 200 μm or more.

Furthermore, the bulk density of the breathable sheet (3) is preferably 1.00 to 8.50 g/cm 3, more preferably 1.50 to 4.50 g/cm 3, and even more preferably 2.00 to 3.00 g/cm 3. The bulk density (g/cm 3 ) of the breathable sheet can be calculated by {basis weight of breathable sheet (g/m 2 )}/{thickness of breathable sheet (mm ⁾ ×10 −3 }, since the breathable sheet ( ³ ) is less likely to change shape due to suction pressure when the breathable sheet ( ³ ) is suction-fixed to the adsorption stage ( ¹ ) or suction portion, and the breathable sheet ( ³ ) has ^less surface irregularities and can achieve clear printing.

The breathable sheet (3) of the present invention can be used as is, but the outer periphery of the breathable sheet (3) may be secured with tape or the like to improve adhesion between the breathable sheet (3) and the adsorption stage (1). In addition, even if the areas of the nonwoven fabric layer (3b) and the support layer (3a) in the breathable sheet (3) are the same, the areas of the nonwoven fabric layer (3b) and the support layer (3a) may be different, such as the area of the nonwoven fabric layer (3b) being smaller than the area of the support layer (3a) or the area of the nonwoven fabric layer (3b) being larger than the area of the support layer (3a).

Here, we will explain an example of a method for producing the breathable sheet (3) of the present invention.

First, prepare the nonwoven fabric that constitutes the nonwoven fabric layer (3b) described above, and the woven or knitted fabric that contains a ferromagnetic material that constitutes the support layer (3a) described above.

Next, the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material are layered, and the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material are bonded to produce the breathable sheet (3) of the present invention in which the nonwoven fabric layer (3b) and the support layer (3a) containing the ferromagnetic material composed of the woven or knitted fabric are bonded. At this time, the method of bonding the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material includes, for example, a method of applying an adhesive composed of an organic resin between the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material, a method of sandwiching a sheet-like material composed of a low-melting point organic resin between the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material and subjecting it to a heat roll or a heat press machine, etc., to melt at least a part of the sheet-like material, and bonding with the sheet-like material melted by heat, and a method of subjecting a laminate of the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material to a heat roll or a heat press machine, etc., to melt at least a part of the constituent fibers of the nonwoven fabric, and bonding with the constituent fibers of the nonwoven fabric melted by heat.

In the case where the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material are bonded to each other by an organic resin such as an adhesive or a sheet-like material in producing the breathable sheet (3) by the above-mentioned method, the basis weight of the organic resin is preferably 3.0 g/ ^m2 or more, more preferably 10 g/ ^m2 or more, and even more preferably 15 g/ ^m2 or more so that the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material can be firmly bonded to each other. On the other hand, if the basis weight of the organic resin is too large, the adhesive fills the voids in the support layer (3a), and the breathable sheet (3) may not be fixed by suction pressure, so that a basis weight of 100 g/ ^m2 or less is practical.

In addition, when bonding a nonwoven fabric to a woven or knitted fabric containing a ferromagnetic material by melting at least a portion of the constituent fibers of the nonwoven fabric, it is preferable to melt the constituent resins of the nonwoven fabric by heating at a temperature at least 20°C higher than the lowest melting point of the constituent resins of the nonwoven fabric, to allow at least a portion of the constituent fibers of the nonwoven fabric to melt and allow some of the constituent fibers of the nonwoven fabric to sufficiently penetrate into the voids in the support layer (3a), and to cause the constituent resins of the nonwoven fabric to flow and allow some of the constituent resins of the nonwoven fabric melted by heat to penetrate into the voids in the support layer (3a).

If necessary, the thickness of the breathable sheet (3) can be adjusted by bonding the nonwoven fabric and the woven or knitted fabric containing the ferromagnetic material together and then subjecting the breathable sheet (3) to a roll or press.

Below, as examples of the present invention, various breathable sheets including preferred embodiments of the present invention were prepared and the results of their evaluation are described. However, the present invention is not limited to the following examples, and the numerical conditions, etc. can be designed as desired and appropriate within the scope of the purpose of this invention.

(Preparation of nonwoven fabric)
Polyacrylonitrile with a weight average molecular weight of 200,000 was dissolved in N,N-dimethylformamide to a concentration of 16 wt%, to prepare a polymer solution (viscosity: 2000 mPa·s). Next, in a space surrounded by a case (length: 1000 mm, width: 1000 mm, height: 1000 mm), a metal nozzle with an inner diameter of 0.41 mm capable of discharging the polymer solution was placed in a state connected to a DC high voltage device, and an endless belt for collecting the discharged polymer solution was earthed and placed in the case. By applying a voltage of 17 kV to this metal nozzle, the polymer solution was discharged at a rate of 3 g/h to form fibers, and a fiber aggregate composed of continuous fibers with a fiber diameter of 0.4 μm was formed.
Furthermore, an acrylic resin binder liquid was applied to the fiber aggregate and dried to obtain a nonwoven fabric layer (basis weight: 26 g/ ^m2 , of which the basis weight of the acrylic resin binder: 9 g/ ^m2 , thickness: 65 μm, porosity: 65%, air permeability: 0.34 ( ^cm3 / ^cm2 /s)).

(Preparation of metal mesh A)
A metal mesh A (plain weave, basis weight: 465 g/m ² , thickness: 0.214 mm, wire diameter: 0.10 mm, mesh spacing: 0.150 mm) was prepared as a ferromagnetic material and a woven stainless steel fabric that is attracted by magnetic force.

(Preparation of metal mesh B)
A metal mesh B (plain weave, basis weight: 479 g/m ² , thickness: 0.186 mm, wire diameter: 0.10 mm, mesh spacing: 0.150 mm) was prepared as a stainless steel fabric that is not attracted by magnetic force.

Example 1
The above-mentioned nonwoven fabric and metal mesh A were combined and thermocompressed (pressure: 0.02 MPa) in a press machine heated to 110° C. to prepare a breathable sheet (basis weight: 491 g/m ² , thickness: 0.245 mm).

(Comparative Example 1)
The above-mentioned nonwoven fabric and metal mesh B were combined and thermocompressed (pressure: 0.02 MPa) in a press machine heated to 110° C. to prepare a breathable sheet (basis weight: 505 g/m ² , thickness: 0.245 mm).

(Measurement of the air leak rate of a film through a breathable sheet)
(1) As a substrate, a commercially available non-breathable polyethylene terephthalate film (thickness: 50 μm) was cut into a square having sides of 170 mm.
(2) The breathable sheets of the Examples and Comparative Examples were cut into squares with each side measuring 190 mm.
(3) A commercially available vacuum suction device was prepared, which had a flat suction stage with a total of 225 circular suction ports, each 1.5 mm in diameter, arranged in a grid pattern (15 vertically and 15 horizontally) at 10 mm intervals, and each side of the opening area was 140 mm long.A magnet measuring 20 mm in length, 10 mm in width and 5 mm in height was attached with tape to the main surface of the suction stage opposite the main surface on which the breathable sheet was placed, with one magnet in the center of the suction stage and eight magnets in eight places around the periphery of the suction stage, for a total of nine magnets being attached to the suction stage.
(4) A polyethylene terephthalate film was placed on the suction stage so as to cover the entire open area of the suction stage, and the vacuum pump was operated. The output of the vacuum pump was adjusted so that the gauge pressure at this time was -10 kPa. After the adjustment, the vacuum pump was stopped, and the polyethylene terephthalate film was removed from the suction stage.
(5) Next, the breathable sheet and base material were placed in sequence so that the suction stage and the support layer of the breathable sheet were in contact with each other so as to cover the entire open area of the suction stage, and so that the entire main surface of one of the polyethylene terephthalate films was overlapped with the breathable sheet. In this state, the vacuum pump was operated at the output set in (4).
The gauge pressure at this time was designated as A (kPa), and the air leak rate was calculated from the following formula.
(Air leak rate) = {1 - (A/(-10))} x 100 (%)

The gauge pressure and air leak rate for the examples and comparative examples are shown in Table 1 below.

The breathable sheet of Example 1, which is made of a ferromagnetic support layer that is attracted to magnetic force, has a lower air leak rate than the breathable sheet of Comparative Example 1, which is made of a non-ferromagnetic support layer that is not attracted to magnetic force, and it was found that the adsorption stage and the breathable sheet can be firmly fixed, and as a result, the film can be firmly attracted and fixed to the adsorption stage via the breathable sheet.

From the above, it has been found that the breathable sheet laminated with a support layer containing the ferromagnetic material of the present invention is a breathable sheet that can be firmly fixed to the adsorption stage of the vacuum adsorption device or the suction part of the vacuum transport device by the suction force and magnetic force when the ferromagnetic material is adsorbed and fixed to the adsorption stage of the vacuum adsorption device, or when the non-breathable substrate is adsorbed and vacuum transported by the suction part of the vacuum transport device, due to the suction force and magnetic force that attracts the support layer constituting the breathable sheet. As a result, it is a breathable sheet that can adequately adsorb and fix the non-breathable substrate.

When printing on the surface of a non-breathable substrate fixed by suction to an adsorption stage, this breathable sheet is used by being interposed between the adsorption stage and the non-breathable substrate, and can form a fine, clear, desired print pattern on the surface of the non-breathable substrate.

The invention also relates to a breathable sheet that is placed between the suction part of a vacuum transport device and a non-breathable substrate during vacuum transport, in which the non-breathable substrate is suctioned and fixed by the suction part of the vacuum transport device, and the non-breathable substrate can be transported without being deformed by the suction force of the suction part of the vacuum transport device.

The present invention has been described above in accordance with a specific embodiment, but modifications and improvements that are obvious to those skilled in the art are included within the scope of the present invention.

1: Adsorption stage 2: Suction port 3: Breathable sheet 3a: Support layer 3b: Nonwoven fabric layer 4: Non-breathable substrate 5: Ink application member

Claims (3)

When printing is performed on the surface of a non-air-permeable substrate fixed by suction on a suction stage of a vacuum suction device, the substrate is interposed between the suction stage and the non-air-permeable substrate.
Alternatively, when the non-air-permeable substrate is suctioned and fixed by the suction part of a vacuum conveying device and conveyed by vacuum, the breathable sheet is used by being interposed between the suction part and the non-air-permeable substrate,
A nonwoven fabric layer in contact with the non-breathable substrate and a support layer made of a woven or knitted fabric in contact with the adsorption stage or the suction portion are laminated together,
The breathable sheet, wherein the support layer comprises a ferromagnetic material. A printing device used to print on the surface of a non-breathable substrate, comprising the vacuum suction device equipped with an adsorption stage capable of adsorbing ferromagnetic material by magnetic force, and the breathable sheet described in claim 1. A conveying device used to convey non-breathable substrates, comprising the vacuum conveying device having a suction portion capable of magnetically attracting ferromagnetic material, and the breathable sheet described in claim 1.