JPS5915288B2 - Manufacturing method of composite sheet with micro pores - Google Patents

Description

[Detailed Description of the Invention] Conventionally, special sheets in which a composite sheet of non-woven fabric and plastic film is integrated with a large number of minute ventilation holes have been manufactured using plaster, silica gel, etc., in order to keep food dry. As a bag for storing fine desiccant powder, or as a heat-generating heat-insulating bag for storing fine powders such as manganese dioxide and iron dioxide, which chemically generate heat by reacting with oxygen in the air.
Furthermore, recently, it has been applied to various medical applications such as high-pressure sterilization bags.

The present invention relates to a method for manufacturing a composite sheet having a large number of micropores on the entire surface for such uses,
Such a sheet is particularly suitable as a material for the heat generating bag.

Conventionally, a method of providing a large number of fine ventilation holes in a composite sheet that integrates a nonwoven fabric and a plastic film is to provide a large number of needle-like objects on the outer surface 10 that are heated to a temperature higher than the decomposition point of the plastic film. A method has been proposed in which the needle-shaped object is brought into contact with the sheet from the plastic film side using a rotating body, and the film is thermally melted at the contact portion.

However, in such a method, it is necessary to heat a large number of needle-like objects, so unless the heating temperature 15 in the width direction of the rotating body is made uniform and the temperature of the needle-like objects located at the outermost surface of the rotating body is constant, It is not possible to provide uniform micropores over the entire surface of the sheet. If the width of the rotating body is small, it is possible to make the temperature of the needle relatively uniform, but if the width is wide, the temperature of the rotating body, specifically the temperature at the tip of the needle, can be made uniform. It is technically almost impossible to make this uniform for all needle groups. Furthermore, since the metal needles are thin wires, the plastic film is easily cooled at the same time as it is melted and decomposed. It is difficult to completely decompose and evaporate the slag.

Therefore, when a needle-like object is used for a long time in the conventional method, it is affected by this sludge, resulting in incomplete perforation, and the sludge that accumulates in thin wires becomes a clump and sticks to the plastic film. Problems such as:

In addition, the viscosity and surface tension have been adjusted to reduce the rapid spread of droplets. Various plastic film 35 solvents can be sprayed as an aerosol, or solvent particles can be printed using a printing method such as a gravure method or an offset method. Another proposed method is to attach plastic film to the surface of the film, heat it with water vapor or heated air, and dissolve it with a solvent attached to the plastic film under slight tension to form vent holes. ing.

However, when spraying a solvent as an aerosol, it is extremely difficult to apply dew droplets uniformly over the entire surface of the film, and most of the solvents are harmful to the human body, making the work environment difficult. make things worse. Also, in the above printing method, when a solvent is transferred to a film to form fine holes, the amount of solvent is extremely small, so spots occur in the amount of adhesion, making it impossible to perforate holes with uniform distribution and diameter. It is.

The present invention solves the drawbacks of the various methods mentioned above, and in particular, creates a composite sheet with fine pores so that the fine powder contained therein does not scatter to the outside, has a uniform distribution, and can control air permeability. The present invention provides a method for drilling a hole in a hole. The gist of the present invention is to attach a large number of needle-shaped objects having an inclination, preferably an inclination of 10 to 600, in the direction of sheet movement with respect to the perpendicular direction of the composite sheet surface, and having a straight conical tip to the nonwoven fabric of the sheet. The holes are made in contact with each other from the surface side.

To explain the present invention along the drawings, FIG. 1 is for explaining an example of the processing process when carrying out the method of the present invention, and shows a brass melt extruded by a T-die extruder 1. After the thick film 2 and the nonwoven fabric 3 are integrated by the rubber roller 4 and the film cooling roller 5 to form a composite sheet 6, the nonwoven fabric side is turned over so that it is the top side, and then an elastic body is coated on the outer surface. When the ball passes between the rotary body 7 and the rotary body 8 having a needle-shaped object on its outer surface which rotates in contact with the rotary body 7, a large number of fine ventilation holes are punched, and then the ball is wound up as a winding ball 9.

In addition, in FIG. 1, guide rollers 10 and 11 are installed before and after the rotating body 7, which rotate freely and are pressed by the rotating body 7, but with these, the composite sheet 6 vibrates while running, causing minute perforations. This was done to avoid any inaccuracies. FIG. 2 illustrates a state in which the rotary body 8 perforates the composite sheet 6 when a rotary body having needle-shaped objects 12 on the outer surface is used as an example of perforation according to the present invention.

The needle-shaped object 12 has a conical tip and has an angle θ in the direction of movement of the composite sheet 6 with respect to the vertical direction. The necessity of the inclination angle θ of this needle-shaped object will be explained in detail with reference to FIGS. 3 and 4. 3 and 4 are partially enlarged cross-sectional views of a perforated composite sheet formed as a storage bag for heat-generating materials, etc., in which fine powder is stored. The fine powder contained therein, 14 a plastic film, and 15 a nonwoven fabric.

The tissue of the nonwoven fabric that has been penetrated by the needle-like object gradually recovers its elasticity and recovers to a state where the needle-like object's penetration hole is closed, but the density of the tissue in that part does not recover to the original density of the tissue. Therefore, the air permeability is high, and a low-density structure portion 17 is formed in which fine powder can easily fly out. Now, Fig. 3 shows the case where the needle-like objects are perforated perpendicularly to the sheet surface from the nonwoven fabric surface.
Since the perforated portion 16 of the plastic film is vertically and concentrically connected to the low-density tissue portion 17 of the nonwoven fabric, the fine powder 13 passes through the perforated portion 16 of the plastic film to the low-density tissue portion 17 of the nonwoven fabric. The tissue portion 17 will more easily protrude onto the outer surface 18 of the nonwoven fabric 15.

On the other hand, FIG. 4 shows the case where the perforation is made with a needle-shaped object having an inclined angle, and the perforation part 16 of the plastic film is concentrically connected to the low-density tissue part 17 of the nonwoven fabric. Since the fine powder 13 has an inclination angle, even if the fine powder 13 exits from the perforated part 16 of the plastic film to the low-density tissue part 17 of the nonwoven fabric, it immediately returns to the nonwoven fabric's original density tissue part. However, since the perforations 16 of the plastic film and the outer surface 18 of the low-density tissue portion 17 of the non-woven fabric are completely misaligned, they easily pop out onto the outer surface of the non-woven fabric. Therefore, the larger the angle of inclination of this needle-like object, the better the result in preventing the fine powder from flying out.However, as can be seen from Figure 2, the angle of inclination of the needle-like object is too large. On the other hand, this will result in tearing the sheet and cause breakage of the needle-like object.Next, when punching many fine holes in the plastic film of the composite sheet with a needle-like object, insert the needle-like object from the non-woven fabric side. need to be penetrated.

The reason for this will be explained with reference to FIGS. 5 and 6. Fifth
6 are partially enlarged cross-sectional views showing the state in which the needle-like object perforates the composite sheet, and in the figure, 19 is the tip of the needle-like object, 2
0 is a plastic film, 21 is a nonwoven fabric, and 22 is an elastic body such as a rubber roller.

FIG. 5 shows a state in which needle-like objects penetrate from the 20th surface of the plastic film of the composite sheet. In general, the density of the plastic film 20 is significantly higher than the density of the nonwoven fabric 2], so the tip of the needle-shaped object receives considerable resistance when punching the plastic film, and the plastic film 20 around the perforation 23 of the plastic film The hole is drilled in such a way that it is stretched. At this time, the structure of the nonwoven fabric bonded to the plastic film surface does not always have a uniform density throughout, but is a continuum of structures with so-called local density differences, so that If there are many needles to be inserted,
Since the resistance force applied to each needle-shaped object is different, the diameters of the holes perforated in the plastic film 20 are completely different. In other words, the method shown in FIG. 5 attempts to use a needle-like object to make a large number of holes of uniform diameter in the film placed on the cushion material, which is naturally a difficult technique.

In contrast, Fig. 6 shows a method in which a needle-like object is penetrated from the non-woven fabric 21 side of a composite sheet, and the needle-like object first penetrates the structure of the non-woven fabric. The elastic body 22 reaches the upper surface of the plastic film 20 after being easily penetrated by a resisting force, and has a density much higher than that of a non-woven fabric such as a rubber roller, and yet has a significantly lower cushioning property than that of a non-woven fabric. Since the tip of the plastic film 20 abuts and is prevented from penetrating, the plastic film 20 is perforated with holes having a uniform diameter.

Therefore, the air permeability can be easily controlled simply by changing the angle and thickness of the conical tip of the needle. As explained above, if the method of the present invention is used, the apparatus is extremely simple, and ventilation holes having uniform distribution and hole shape can be punched over the entire surface of the composite sheet. It is possible to control the air permeability. The method of the present invention will be explained in more detail with reference to Examples below. Example 1 By the composite sheet manufacturing process shown in Fig. 1, the basis weight was 60f.
! /M2 rayon 100(f) nonwoven fabric (cellulose nonwoven fabric manufactured by Mitsubishi Rayon Co., Ltd., registered trade name: TCF)
A composite sheet having a width of 1600 ml was prepared by laminating the sample and a polyethylene film having a thickness of 40 μm extruded by a T-die extruder.

This composite sheet was treated with a needle from the nonwoven fabric side under the following conditions. The composite sheet processed under the above conditions was measured using the air permeability measuring method according to JISP-8117, and as a result, a composite sheet having an air permeability of 30 sec/100 CC was obtained.

Furthermore, this sheet was processed into a bag shape of 120 mm x 90 mm with nonwoven fabric arranged on the outer surface.
A heat-generating heat-retaining bag containing 0μ microparticles of the heat-generating composition 409 was created and put to practical use. As a result, the outer surface temperature of the nonwoven fabric was 40.
It was stable between .degree. C. and 45.degree. C., and the fine particles of the exothermic composition did not come out on the outer surface of the nonwoven fabric, causing no practical problems.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an example of the processing process when carrying out the method of the present invention, and FIG. 2 is a diagram illustrating a state in which a rotating body or composite sheet having needle-like objects on its outer surface is perforated. 3 and 4 are partially enlarged cross-sectional views of a perforated composite sheet formed as a storage bag and containing fine powder. The symbols in the figure are as follows. 1: T-die extruder, 2: Plastic film, 3: Nonwoven fabric, 4:
Rubber roller 1, 5: Cooling roller 6: Composite sheet, 7
: Elastic body-covered rotating body, 8: Rotating body having needle-like objects on the outer surface, 9: Winding ball, 10, 11: Guide roller, 12: Needle-like objects, 13: Fine powder, 14: Plastic film, 15
: Nonwoven fabric, 16: Film perforation, 17: Low density tissue part of nonwoven fabric, 18: Outer surface of low density tissue part of nonwoven fabric.

Claims (1)

[Claims] 1. When providing a large number of fine ventilation holes in a composite sheet that integrates a nonwoven fabric and a plastic film, the holes are inclined in the traveling direction of the sheet with respect to the direction perpendicular to the surface of the composite sheet, and the tip thereof has a conical shape. A method for producing a composite sheet having fine pores, which comprises perforating the sheet with a large number of needle-like objects in contact with each other from the nonwoven fabric side of the sheet.