JPH0441197A - Cutting method for thermomelting sheet and device thereof - Google Patents

Abstract

PURPOSE:To increase durability and yet to make the shape of a slit unlimitted, by giving a ultrasonic vibration energy to a sheet by a ultrasonic vibration horn in the transfer process while passing a thermomelting sheet in the space with the edge opposed to the ultrasonic vibration horn. CONSTITUTION:Plural edges 30 are fitted to the outer peripheral part of a rotating roll 2 at interval in the roll axial direction and an edge unit 3 that the outermost operipheral line of the cutting edge 30 is discontinuous is arranged. A ultrasonic vibration horn 6 for giving ultrasonic vibration energy commonly to these edge groups 30 is arranged in opposition to the edge unit 3. The ultrasonic vibration energy is given by the ultrasonic vibration horn 6 to a sheet 7 in the transfer process while passing the thermomelting sheet (nonwoven cloth) 7 between the ultrasonic vibration horn 6 and edge groups 30 and the cutting according to the shape of the edge is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for cutting a heat-fusible sheet. In particular, as a sheet to be cut,
Examples include thermoplastic resins or sheets mainly made of thermoplastic resins, such as nonwoven fabrics.

[Conventional technology]

Usually, nonwoven fabrics are often used as the top sheet of paper diapers, that is, the sheet that comes into contact with the wearer's skin.

It is also known that it is effective to make holes in this nonwoven fabric so that urine can quickly pass through and be absorbed into the absorbent body.

On the other hand, the present applicant has been developing a disposable diaper with barrier cuffs, but in the process, the side part of the top sheet is connected to the upright end of the barrier cuff to solve the problem of absorbing soft stool, which has been considered a problem in the past. In this way, a chevron-shaped part is formed in the barrier cuff part, and a slit is formed in advance along the longitudinal direction of the disposable diaper in the top sheet corresponding to the slope part on the center side of the disposable diaper of the chevron-shaped part. At times, the barrier cuffs stand up due to the contraction of the elastic member attached to the barrier cuffs.
Along with this, the slit becomes open, and allowing soft stool to pass through this opening and storing it in the chevron portion is extremely effective in preventing stool rash caused by contact between soft stool and the skin. We found that.

[Problem to be solved by the invention]

However, the following methods are mainly considered as methods for forming the slits.

(1) For example, forming an unsupported part between two rolls,
A laser cutting method in which you cut while applying a razor blade between the two.

(2) Shear cutting method, in which the sheet is cut between two rotating blades.

(3) Die cutting method.

(4) Score cutting method.

However, the razor cutting method (1) above is not suitable for practical use because the blade is subject to severe wear and has to be replaced frequently (2). Since the blade is highly dependent on the blade, it is necessary to have extremely high precision, which makes it expensive, and requires a great deal of effort to adjust the holding pressure, which causes many problems in actual line operation.

In the die-cutting method (3), when cutting a piece of low-density nonwoven fabric for disposable diapers, and when slitting a complex shape, the blade must have extremely high precision, and adjustment frequency is required. There are many problems in applying it to continuous actual lines.

Furthermore, when attempting to obtain a slit with a curved shape instead of a straight line, the laser cutting and shear cutting methods cannot be employed in principle. Moreover, what is common to both methods is that the blade holder requires a certain amount of thickness, so the widthwise spacing of the slits is 5 =
It cannot be:

Therefore, an object of the present invention is to provide a material that is highly durable, does not impose restrictions on the shape of the slit, and is suitable for actual operation.

[Means to solve the problem]

The above problem can be solved by applying ultrasonic vibration energy to the sheet by an ultrasonic vibration horn during the conveyance process while passing a thermofusible sheet between an ultrasonic vibration horn and an opposing blade. This can be solved by giving the blade a certain shape and cutting it in a way that corresponds to the shape of the blade.

In addition, in terms of equipment, a plurality of blades are attached to the outer circumference of a rotating roll at intervals in the roll axis direction, and the outermost circumferential line of the cutting blade is discontinuous, and these blade groups are used. This problem can be solved by arranging an ultrasonic vibration horn that commonly applies ultrasonic vibration energy to the blades, and passing a thermofusible sheet between the ultrasonic vibration horn and the blade group.

[Effect]

According to the present invention, when ultrasonic vibration energy is applied to the sheet by the ultrasonic vibration horn during the conveyance process while passing the thermofusible sheet between the ultrasonic vibration horn and the opposing blade, It is possible to perform cutting that corresponds to the shape of the blade.

In addition, since cutting is performed using ultrasonic waves, there is very little wear and tear on the blade, and in reality it can be operated continuously at full capacity for more than two weeks, compared to the razor cutting method, which requires replacing the blade in just a few hours. The effect is remarkable when compared. Furthermore, once the adjustment is performed, subsequent adjustments are not necessary.

Furthermore, in contrast to the shear cutting method, the shape of the blade can be any suitable shape, such as a wave shape. on the other hand,
Since the blade is not damaged, the blade pieces will not be mixed into the product, making it safe when applied to disposable diapers, for example. Further, the fibers do not become frayed and remain at the cutting edge, and sharp cutting can be performed.

[Specific structure of the invention]

Hereinafter, the present invention will be explained in more detail by way of examples with reference to the drawings.

Figures 1 and 2 show the entire device, bearing 1
, (3), the rotary roll 2 is rotated in the circumferential direction by a rotational drive source (not shown), and a blade unit 3.3 is detachably fixed to the rotary roll 2 by a bolt 4. Furthermore, between the blade units 3.3 and against the rotary roll 2 a stabilizing bearing roller 5.5 is arranged, which stabilizes the rotation of the rotary roll 2.

On the other hand, the blade unit 3, as shown in FIGS. 4 and 5,
It has a plurality of blades 30, 30 in the axial direction, and each month 30 has a convex part 30A and a concave part 30B in the circumferential direction, and faces the groups of these blades 30. An ultrasonic vibration horn 6 is provided. As shown in FIG. 1, a thermofusible sheet such as a nonwoven fabric 7 is conveyed between an ultrasonic vibration horn 6 and a group of blades 30. As shown in FIG. Further, as shown in FIG. 6, the ultrasonic vibration horn 6 includes a power supply 6 connected to a power source 60.
Electrical energy having a predetermined frequency is applied to the converter 62, and after being converted into mechanical vibration in the converter 62, mechanical vibration force is applied via the booster 63. An example of the shape of the ultrasonic vibration horn 6 is shown in FIG.

In the device configured in this way, in the process of conveying the nonwoven fabric 7 between the ultrasonic vibration horn 6 and the group of blades 30,
The ultrasonic vibration horn 6 mechanically vibrates, and its tip is a blade 30.
As a result, an intramolecular mechanical stress is generated in the portion of the nonwoven fabric 7 corresponding to the convex portion 30A of the blade 30, and the nonwoven fabric 7 is softened and melted by frictional heat, thereby being cut. Furthermore, no cutting is performed when corresponding to the recess 30B. As a result, discontinuous slits S are formed in the circumferential direction of the blade 3o. In addition, if the positions of the convex portions 30A are shifted in advance between adjacent blades 30, 30, staggered slits S can be formed on both sides of the nonwoven fabric 7, as shown in FIG.

On the other hand, the slits may not be arranged in a staggered manner, but may have the same longitudinal position, or by changing the shape of the blade, the slits may have an integral shape as shown in Fig. 9. It can be made into an appropriate shape such as a slit S'.

The ultrasonic vibration frequency is preferably 20 to 40 KHz. When the frequency is high, slitting is possible with a small vibration displacement, the impact on the group of blades 30 is small, the life of the blades 30 is extended, and the device has the advantage of being compact.

By the way, the height h of the blade 30 is 1 to 5 rMi, the tip thickness 10 of the blade 30 is 0.05 to 0.50 mm, the pitch P with the blade 30.30 is 1 to 20 mm, and the circumferential length of the convex portion 30A. 11
is 5 to 20, and the circumferential length 12 of the recess 30B is 1 to 10.
mm, the angle θ of the blade 30 can be 10 to 30 degrees, and the contact pressure between the two blades 30 and the ultrasonic vibration horn can be 3 to 6 kg. Furthermore, the heat-fusible sheet referred to in the present invention may be a general thermoplastic plastic sheet or a nonwoven fabric. This nonwoven fabric can have a weight of 10 to 50 g/m.

On the other hand, the conveying speed of the sheet and the circumferential speed of the blade 30 may be the same or may be different.

The present invention can be suitably applied, for example, in the case of forming a top sheet of a paper diaper, as in the following example.

Therefore, an example of the structure of a disposable diaper will be explained with reference to FIGS. 10 and 11. A liquid-impermeable sheet 11 made of polyethylene or the like, and a liquid-permeable sheet made of a nonwoven fabric or the like having a width narrower than that of the liquid-impermeable sheet 11. An hourglass-shaped absorbent body 13 having a certain degree of rigidity, for example, is interposed between the absorbent body 13 and the absorbent body 13 made of cotton-like pulp or the like.

The absorbent body 13 is wrapped with lip-groove absorbent paper to maintain its shape. On the sides of this absorbent body 13, the liquid-impermeable sheet 11 and a preferably hydrophobic barrier sheet 16 are bonded with a hot melt adhesive (the bonded portion is shown by shavings in a plan view and by diagonal grids in a cross-sectional view). ), flap F without absorber 13
is formed.

On the other hand, the paper diaper has barrier cuffs B, B on both sides, and the barrier sheets 16 and 16 constituting the cuffs have a liquid-impermeable sheet on the outer side of the absorbent body 13 on the outer side as described above. They are fixed to each other with a single layer and hot melt adhesive.

Furthermore, a liquid-permeable surface sheet 15 made of non-woven fabric or the like is placed over the protruding portions of the hydrophobic barrier sheet 16.16.
are arranged. The outer side portion of the top sheet 15 is fixed to the protruding portion of the barrier sheet 16, particularly preferably near the contact strip 16b, which will be described later, with a hot melt adhesive or the like.

Further, in detail, the barrier sheet 16 is the sheet 11
Only the outer part is fixed to the liquid-impermeable sheet 11 with a hot melt adhesive or the like, and the inner part is not fixed to the liquid-permeable sheet 12.

For example, the barrier sheet 16 has a base flap 16a and a contact band 16b that form a T-shape (however, they do not need to be perpendicular to each other) when installed.
b constitutes the horizontal character of the letter T. At least one elastic member 17.17.17 made of rubber thread or the like is fixed to the hit band 16b by means of a hot melt adhesive.

Reference numeral 1B denotes an elastic waist band made of breathable and liquid-impermeable polyurethane foam, which is interposed between the sheets 11 and 12.

On the other hand, the entire width of both longitudinal ends of the barrier sheet 16 and 16 is coated with hot melt adhesive or the like to prevent the barrier cuffs B, B from protruding diagonally inward and warping outward during use. , surface sheet 15, liquid permeable sheet 1
2, and is fixed to the liquid-impermeable sheet 11. 19
is a fastening tape.

On the other hand, the liquid-permeable sheet 12 is arranged to have the width of the hollow absorbent body 13. This liquid-permeable sheet 12 mainly has the function of diffusing urine.

The side surface of this liquid-permeable sheet 2 and the liquid-impermeable sheet 11
A liquid-impermeable band 21 made of a plastic film such as polyethylene extends in the longitudinal direction and has a width spanning the inner side of the joint portion. This liquid-impermeable zone 2
1 and the liquid-impermeable sheet 11, one or more elastic elastic members 14, 14 for bending and deforming made of rubber thread or the like are interposed, and the elastic member 14, 14 for bending and deforming is interposed between the elastic member 14 and the liquid-impermeable sheet 11. It is fixed to the liquid-permeable band 21 and the liquid-impermeable sheet l. Further, at least the inner elastic elastic member 14 is close to the side edge of the absorbent body 13 at a position where the side portion thereof is bent.
Preferably they are closely spaced with dimensions of less than 1.9 an.

In the disposable diaper configured in this way, when the product is unfolded from the folded state and put on the wearer, the barrier cuff B tends to straighten due to the contractile force of the elastic elastic member 17 mainly made of rubber thread. It will be done. However, while the sheet I, I2.15, absorbent body 13, etc. bend from the belly to the back, no contraction force acts on the absorbent body 13, which basically has some degree of rigidity, so the barrier Cuffs B and B begin to stand up, facing slightly toward the center line.

According to the embodiment, when the top sheet 15 is provided, the contraction force of the elastic elastic member 17 causes both sides of the top sheet 15 to separate from the liquid-permeable sheet 12 as the barrier cuffs B rise when worn. This forms a pocket space for absorbing loose stools.

When urine is excreted in this state, the urine is quickly absorbed into the absorbent body 13 through the top sheet 15 and the liquid permeable sheet 12 in contact with the top sheet 15. In addition, the liquid of difficult feces excreted between the barrier cuffs B and B is similarly absorbed. The solid content of loose stool mainly enters the pocket space through the openings opened by the slits S formed on both sides of the top sheet 15 as the barrier cuffs B rise. This prevents solid content of stool from remaining on the top sheet 15, thereby preventing stool staining.

〔Example〕

Using the apparatus shown in the drawings, slits were formed in the nonwoven fabric in the shape shown in FIG. 9. As a result, the slits could be formed sharply without any fuzz, and the paper diapers shown in Figures 10 and 11 were manufactured continuously for more than two weeks, and it was confirmed that there was little wear and tear on the blades (no need to replace them). As the ultrasonic vibration slitter, one manufactured by Planson Japan Co., Ltd., which is normally used for melt joining of plastics, was used.

〔Effect of the invention〕

As described above, the present invention provides advantages such as being highly durable, not restricting the shape of the slit, and being suitable for actual operation.

[Brief explanation of drawings]

Figure 1 is a front view of the device of the present invention, Figure 2 is a side view thereof, Figure 3 is a schematic diagram of an example of the line of the cutting part, Figure 4 is a partially enlarged front view of the blade unit, and Figure 5 is the blade. 6 is a configuration diagram of the ultrasonic vibration device, FIG. 7 is a perspective view of a horn example, and FIGS. 8 and 9 are plan views of a slit example.
FIG. 10 is a plan view of an example of a paper diaper, and FIG. 11 is a perspective view. 2... Rotating roll, 3... Blade unit, 6... Ultrasonic vibration horn, 7... Nonwoven fabric, 15... (Nonwoven fabric) surface sheet, 30... Blade, 30A... Convex Part, 30
B... recess, s, s'... slit.

Claims (2)

[Claims] (1) During the conveyance process while passing a thermofusible sheet between an ultrasonic vibration horn and an opposing blade, ultrasonic vibration energy is applied to the sheet by the ultrasonic vibration horn, and the blade A method for cutting a thermofusible sheet, which is characterized by cutting according to the shape. (2) A plurality of blades are installed on the outer circumference of a rotating roll at intervals in the roll axis direction, and the outermost circumferential line of the cutting blade is discontinuous, and a blade common to these blade groups is used. A thermofusible sheet, characterized in that ultrasonic vibration horns that give ultrasonic vibration energy are placed facing each other, and the thermofusible sheet is passed between the ultrasonic vibration horn and the blade group. cutting equipment.