JPH0260389B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a method for manufacturing a breathable support. More particularly, the present invention relates to a method for producing a breathable support having a desired degree of controlled air permeability. (Technical background) Traditionally, chemicals that interact with specific components in the air, such as desiccants, oxygen scavengers, freshness-preserving agents, deodorizing agents, and heat-generating agents, and insect repellents, fungicides, and fragrances, etc. BACKGROUND ART A sheet-like material whose air permeability is controlled to a desired degree is used as a bag for packaging a substance that achieves a specific effect by volatilizing the drug into the air. The following are known as these breathable sheets. (1) Materials that do not have thermal adhesive properties, such as cotton or pulp, and materials that have adhesive properties, such as polyolefin, are combined; (2) Non-woven fabrics or paper are used as a base material, and Nonwoven fabrics with thermal adhesive properties bonded together by thermocompression have also been used. However, since it is extremely difficult to control the air permeability of these sheets, they are used only in very limited applications. In addition, breathable sheets are also used, in which a non-breathable resin film is laminated onto a non-woven fabric and holes are then punched with a needle. There was a drawback that the medicine or composition stored in the container could spill out from the hole. On the other hand, sheets in which air permeability is controlled by laminating a nonwoven fabric with a resin film in which air holes are formed in advance have been used, but these sheets have the following drawbacks. (a) The base material is limited to thermally adhesive materials. (b) Base materials are limited to those with strong heat resistance. (c) Since heat and pressure are used, the pores in the perforated film are easily deformed, and if the base material has uneven thickness, the shape and size of the pores in the perforated film may become uneven. (Prior Art) Recently, a sheet in which a large number of fine through-holes are present over the entire plane (hereinafter abbreviated as a microporous sheet) has been developed, and it has come to be used in applications that require air permeability. Ta. Since the air permeability of a microporous sheet is determined at the stage of its manufacture, it is not possible to obtain the amount of air permeability desired by the user depending on the intended use. For this reason, secondary control is also performed by laminating a resin film with ventilation holes in advance, as in the case of non-woven fabrics, but as with non-woven fabrics, the amount of ventilation can be precisely controlled. cannot be controlled. For example, a breathable sheet obtained by thermocompression bonding a perforated thermoplastic film to a microporous sheet is produced by applying heat, pressure, and tension to melt and fluidize the thermoplastic film in the thermocompression bonding process, and then laminating it onto the microporous sheet. Since this is a method in which the thermoplastic film is fixed in place, the shape and dimensions of the perforated portion of the thermoplastic film tend to change easily, resulting in a lack of stability in air permeability. Furthermore, since many of the microporous sheets contain thermoplastic resin as a component, it is inevitable that the air permeability will change due to heat and pressure bonding. However, when pattern-coating a thermoplastic resin coating liquid onto a microporous sheet using a gravure roll to obtain a breathable sheet in which non-coated areas retain air permeability, the amount of coating applied in one coat using the gravure roll is insufficient. However, there are disadvantages in that pinholes occur in the parts and the heat sealability remains in the easy peel range. The method of increasing the coating amount of adhesive resin and/or coating liquid containing adhesive resin as a component is to reduce the number of gravure screen lines, increase the depth of the cells engraved on the gravure roll, and improve adhesive properties. It would be better to increase the amount of transfer of the coating liquid containing resin and/or adhesive resin, but in general, when the plate depth is deep, uneven corrosion of cells engraved on the gravure roll, breakage of banks, etc. In many cases, the bank is too wide, resulting in unfavorable transfer rates and coating surface smoothness. Furthermore, depending on the coating amount, the shape and size of the pattern will not be constant, resulting in unstable air permeability. It is also possible to use a registration device used in gravure printing to coat a large amount of gravure with a pattern other than the one according to the present invention on a microporous sheet, but this method requires new registration marks, and gravure printing Since the distance between the units of the machine is short and the drying speed of the adhesive resin and/or the coating liquid containing the adhesive resin as a component is also limited, there is a drawback that the processing speed is reduced. (Object of the Invention) The present invention eliminates the above-mentioned drawbacks when obtaining an air permeable support by processing air permeability adjustment on a microporous sheet, and makes it possible to control the amount of air permeation to a desired level by keeping the shape and area of the air permeable portions constant. The present invention is intended to provide a method for producing a breathable support with special characteristics. (Structure of the Invention) As a result of intensive studies to eliminate the above-mentioned drawbacks, the present inventors have developed a method for coating a microporous sheet with an adhesive resin and/or a coating liquid containing an adhesive resin as a component. The first step is coating where the coated area remains in a linear shape, and the second step is to leave a linear non-coated area when applying the adhesive resin and/or the coating liquid containing the adhesive resin as a component. It has been found that air permeability can be controlled accurately by intersecting the non-coated area of the first stage coating. The components of the present invention will be explained in detail below. (Microporous sheet) Examples of microporous sheets include Sekisui Chemical Co., Ltd.'s product Cellpore (some made of polyethylene and others made of polypropylene), Dupont's product Tyvek (made of polyethylene), and Tokuyama Soda. Films or sheets such as NF sheet (made of polypropylene) produced by Co., Ltd., woven fabrics, non-woven fabrics, spunbonded products, paper, etc. are suitable. (Coating liquid) Adhesive resins and coating liquids containing adhesive resins include ethylene-vinyl acetate copolymer resin (EVA) and ethylene-acrylic acid copolymer resin (ethylene-ethyl acrylic acid copolymer resin). ) as a base resin, and ethylene-
A coating liquid made of a water-based emulsion containing vinyl acetate copolymer resin as a main component, a coating liquid made of a urethane adhesive resin diluted with ethyl acetate, etc. can be used. (Coating method) When coating a microporous sheet to leave linear uncoated areas in a fixed shape and area, gravure methods, offset gravure methods, etc. can be used, but are limited to these methods. It's not a thing. When applying with the gravure method, the viscosity of the adhesive is 10~
The preferred range is 200-2000 cps, although it can be in the range of 10000 cps. The coating amount varies depending on the solid content of the adhesive, but when using a hot melt adhesive, it is as shown in Table 1.

[Table] (Examples) Examples are shown below to explain the present invention in more detail, but the following examples do not limit the present invention. Example 1 Tyvek (manufactured by laminating polyethylene fibers and heat-pressing them) with a thickness of 0.17 mm, a basis weight of 54 g/m ² , and an air permeability of 5.0 cc/cm ² min according to the Frazier type method air permeability test. A hot-melt adhesive containing ethylene-vinyl acetate copolymer as the main component was coated on a sheet (with fine through-holes on the front and back surfaces over the entire surface) using a gravure coating machine. 11.5 As the first coating, a continuous linear pattern is formed in which coated areas with a width of 5 mm and uncoated areas with a width of 1 mm appear alternately parallel to the running direction of the sheet.
It was applied at a rate of g/m ² . Next, for the second coating, the coating was applied at a rate of 7 g/m ² to form a linear pattern perpendicular to the continuous linear pattern formed by the first coating. . In the second linear pattern formed, the width of the coated area was 5 mm, and the width of the non-coated area was 1 mm. In both the first and second coating, the temperature of the molten hot melt adhesive is
The coating was carried out at 180°C and at a coating speed of 100 m/min. The air permeability of the coated film was 0.15 cc/cm ² ·min in the Frazier air permeability test. Example 2 A water-resistant reinforced paper with a thickness of 200 μm, a basis weight of 150 g/m ² , and an air permeability of 25 c.c./cm ² min determined by the Frazier method air permeability test was coated with ethylene-ethyl acrylic acid using a gravure coating machine. A hot melt adhesive whose main component is a copolymer was applied. For the first coating, a 3mm wide coated area parallel to the sheet running direction and a 2mm wide coated area.
A continuous linear pattern was applied at a rate of 8 g/m ² so that non-coated areas appeared alternately. Next, for the second coating, the width of the coated area is 5 mm, and the width of the non-coated area is 5 mm, so as to intersect the linear coating pattern formed by the first coating at a 60° angle. It was coated at a rate of 8 g/m ² so that the width was 1 mm. In both the first and second coating, the temperature of the molten hot melt adhesive is
The coating was carried out at 180°C and at a coating speed of 100 m/min. The air permeability of the coated sheet was 3 c.c./cm ² ·min as determined by the Frazier type air permeability test. Example 3 The same Tyvek, the same hot melt adhesive, and the same application method used in Example 1 was used. In the first coating, a width of 13 mm was applied so that a continuous linear pattern parallel to the running direction of the sheet was formed.
Coating was carried out at a rate of 11.5 g/m ² so that a coated area with a width of 1 mm and an uncoated area with a width of 1 mm appeared. Next, for the second coating, a 13 mm wide coated area and a 1 mm wide uncoated area are placed so as to intersect at a 45° angle to the continuous linear pattern formed by the first coating. The coating was applied at a rate of 10.1 g/m ² so that the treated areas were formed alternately. The temperature of the melted hot melt adhesive during both the first application and the second application is
The coating was carried out at 180°C and at a coating speed of 100 m/min. The air permeability of the coated sheet was 0.02 cc/cm ² ·min as determined by the Frazier type air permeability test. Example 4 The microporous sheet used in this example was obtained by dispersing fine powder of calcium carbonate in high-density polyethylene resin and molding it into a sheet shape, and had a basis weight of 53 g/m ² , thickness 0.10
mm, the air permeability according to the Frazier method air permeability test is 1
It was cc/cm ² min. A hot melt adhesive containing ethylene-vinyl acetate copolymer as a main component was coated onto the microporous sheet using a gravure coating machine. As the first coating, a continuous linear pattern was applied at a rate of 5.8 g/m ² parallel to the running direction of the sheet so that coated areas of 9 mm width and uncoated areas of 1.0 mm width appeared alternately. I worked on it. The second coating should be applied so that it intersects the continuous linear pattern formed by the first coating at an angle of 60°, and the width of the coated area is 9.5 mm, and the width of the non-coated area is 9.5 mm. A linear pattern was applied at a rate of 7.1 g/m ² so that the width of the strip was 0.5 mm. In both the first and second coating, the temperature of the molten hot melt adhesive is
The coating was carried out at 180°C and at a coating speed of 100 m/min. The air permeability of the coated sheet was 0.06 cc/cm ² ·min as determined by the Frazier type air permeability test. Application example (simple coloring) A hot melt adhesive mainly composed of ethylene-vinyl acetate copolymer was coated uniformly on the entire surface of the same Tyvek as used in Example 3 using a gravure coating machine.
The non-breathable sheet coated at a rate of 8.5 g/m ² in the first coating and 12.1 g/m ² in the second coating was used as one side, and the breathable sheet obtained in Example 3 was used as the other side. The effective part 120 is attached by thermal bonding so that they face each other.
A bag-like product measuring 85 mm was obtained. This was filled with a composition that generated heat by reacting with oxygen, which was prepared by mixing 28 parts of iron powder, 8 parts of activated carbon, 10 parts of water, 3 parts of vermiculite, and 1 part of common salt.
When the heat-generating bag thus obtained was worn on a person's body over a layer of underwear, it maintained a comfortable temperature for 28 hours. (Effects of the Invention) The effects of the present invention are listed as follows. (1) Since the adhesive resin is applied twice, the area where the adhesive resin is applied in two layers (that is, the area that accounts for the majority of the breathable sheet manufactured by the present invention) is completely free of gas. Cut off. (2) There are no drawbacks that occur when a large amount of adhesive resin is applied at one time. (3) The present invention does not have the drawbacks of multiple gravure coating methods that use patterns other than those of the present invention. (4) The air permeability of the breathable sheet can be adjusted reliably. (5) A breathable sheet with strong heat sealing strength can be obtained. (6) It is easy to industrialize.

Claims (1)

[Claims] 1. When applying an adhesive resin and/or a coating liquid containing an adhesive resin to a sheet that has a large number of fine through holes on the front and back surfaces over the entire plane, uncoated areas remain in the form of a line. When applying an adhesive resin and/or a coating liquid containing an adhesive resin as a second step, the linear non-coated area is the same as the non-coated part of the first step coating. A method for producing an air permeable support, characterized in that the coating is applied so as to intersect with the coated part.