JPS609731A - Ultrasonic welding method of paper pressure container - Google Patents

Abstract

PURPOSE:To enable to make solvent welding of a body with a lid body uniformly and firmly extending over the whole circumference and to obtain a paper pressure container whose pressure-resisting strength is high, by a method wherein a little slope is formed on a skirt part of the lid body, contact bonding of an ultrasonic wave application horn is made to perform through a tilting ring, and ultrasonic welding is done by catching the same by a supporting arm. CONSTITUTION:A skirt part 2c to be formed in an X axis direction of a container by keeping a slope of 1/50-1/10 on an external circumference of a lid body 2 obtained by laminating plastic films 2d, 2e on both the sides of paper is fitted by pressure in an end part of a cylindrical body 1 obtained by laminating plastic films 1a, 1b on both the surfaces of paper. In addition to the above, the end part of the body 1 is held strongly against a load from the upper part by a supporting arm 4, and then a tilting ring 3 is inserted into an inner circumferential surface of the skirt part 2c of the lid body 2. When a circular ultrasonic wave application horn 5 is lowered from the upper part and a slope of an inner circumferential part 3b of the tilting ring 3 is pressed strongly, the skirt part 2c is pressed strongly against the end part of the body 1 through wedge action. At this time, an external circumferential surface of the skirt part 2c and an internal circumferential surface of the end part of the body 1 are welded each other by applying an ultrasonic wave to the surfaces for about a second.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises an inner peripheral surface of the end of a cylindrical body made of paper whose inner and outer surfaces are laminated with plastic films, and a lid body made of paper whose inner and outer surfaces are laminated with plastic films. (
The present invention relates to an ultrasonic welding method for paper pressure containers, which uniformly and firmly welds the entire circumference by applying ultrasonic waves to the outer peripheral surfaces of the skirt portions of the top and bottom lids.

In recent years, due to advances in materials and processing methods, some conventional glass bottles or steel cans have been replaced by containers made of materials such as aluminum, plastic, and paper for beverage containers. Most beverage containers are treated as disposable containers5, but empty containers can be collected or recycled even if they are made of recyclable steel or aluminum cans after they are used by consumers.
It is not reused. The reason for this is that the cost of recovery and recycling is high due to labor and transportation costs for recovery and sorting, space for temporary storage, wastewater treatment costs for cleaning water from recovery containers, etc. However, even when disposable steel cans, aluminum cans, Dallas stick bottles, etc.
Even if it is disposed of as garbage, it cannot be incinerated, and even if it is used in a landfill, it creates a cavity, which poses a problem in the use of the land after the landfill.

For these reasons, there is a demand for a switch to paper containers that can be easily disposed of after use, and many beverages, such as milk and juice, have already been replaced with paper containers. However, all of these beverages do not contain carbon dioxide gas, and the pressure inside the container at room temperature is almost equal to atmospheric pressure, so paper pressure-resistant containers for beer and carbonated drinks are rarely seen. I can't do it. The reason why the development of paper pressure-resistant containers has been delayed is that, first, the pressure-resistant specifications required for containers for beer, carbonated drinks, etc. are quite high (the internal pressure of beer is 2 to 2.5 mm at room temperature). 5 to 96”G, 50℃
The internal pressure of a carbonated drink is about 5XMm2G at room temperature.
5 to 9/cyrL2G, 50゛C approximately 7 kg/CWL”
G) Technical difficulties regarding the sealing method arise from two points: first, the joint between the body and the lid cannot be sealed by seaming like a metal can due to poor bending properties of the paper; Aluminum cans and steel cans, which are listed above, are fairly inexpensive, so paper pressure containers are also considered the first choice above.
This difficulty arises from the economic constraints of having a structure that can be manufactured at a low cost, including solutions to these difficulties.

Despite the many obstacles mentioned above, the inventors of the present invention focused on the many benefits that paper pressure-resistant containers have, and as a result of various studies aimed at realizing them, the following knowledge was obtained. That is,
For example, a body can be made by laminating a plastic film on paper with high tensile breaking strength and wrapped in multiple layers and heat treated, and a skirt can be made by mixing pulp fiber with plastic in the form of fibers or powder. The lid is made of a heat-molded spherical shape with a plastic layer formed on it, thereby creating a body and a body that have pressure resistance and waterproofness sufficient to withstand the specifications for beer and carbonated drinks. I was able to obtain each of the lids.

As for the method of combining the body and lid obtained in this way and attaching the lid to the end of the body as a top or bottom lid, the method of bonding with adhesive is not suitable for production on an industrial scale. Furthermore, depending on the type of adhesive, it may not be preferable for the purpose of filling beverages.

In such cases, the best method is to weld the laminated plastic films to each other on the body and lid, and generally heat-sealing by ultrasonic welding, high-frequency welding, or external heating is used. .

However, high frequency welding is limited by the dielectric loss tangent characteristics unique to various plastic materials. The external heating method is extremely inefficient because it applies heat through paper with low thermal conductivity to weld the internal plastic layer. is exposed to the highest temperatures, causing melting and damage. In the end, as a general method, ultrasonic welding is the best method because it instantly welds the joints without leaving any scratches on the surface, but this is difficult to do with the cylindrical paper pressure-resistant container that is the object of the present invention. faced a problem. In other words, in ultrasonic welding of plastics, etc., the surfaces to be welded are usually firmly fixed by applying a pressure of 10 to 20 kg/cIrL2, and ultrasonic waves of around 20 KHz are applied from the outside of the body or the inside of the skirt of the lid. Approximately 1
The force is applied for about 4 seconds, and the target surface is welded by internal heat generation of the member due to high frequency vibration. In order to perform such an operation, a cylindrical body whose side walls are parallel to the axial direction of the container (hereinafter abbreviated as the X axis) and a lid body whose skirt portion is parallel to Even if such an attempt is made, the pressure to fix the joint surfaces is not applied, and the positions of the cylinder and the lid, which have parallel sides, are not constant, resulting in extremely insufficient welding.

Of course, even if the parts of the body and lid to be welded are firmly fixed from the outside, the pressure in the lateral direction of the ultrasonic application horn moving in the XM direction is hardly to be expected. . One way to deal with this problem is to hold the body with the lid inserted horizontally, use a circular support inscribed on the inner surface of the skirt part to withstand the load from above, and then apply ultrasonic waves from above. There is a method of applying ultrasonic waves from outside the fuselage while applying high pressure by lowering the horn vertically. However, with this method, for example, the inner diameter of the fuselage is 74 mm.
In this case, if the welding length is set to 60 mm and the welding operation is repeated approximately 8 times along the periphery, the gap between the inner wall of the body and the outer wall of the lid skirt will be Subtle gaps occur between the two, resulting in uneven welding. Even if welding was performed by changing the operation method and shifting the welding position by 180 degrees, the problem of gaps occurring could not be completely resolved. The reason for this is that when the approximately 60 mm plastic film laminated on the surface of the body and lid is welded, the thickness of the plastic layer decreases, and even though the fit is quite tight when the lid is first inserted into the body, This is thought to be because the effect of this thickness reduction remains in some areas after circumferential welding.

Based on the above findings, the inventor of the present invention continued to study a simple and reliable method of ultrasonic welding of the body and lid body, with the aim of providing a pressure-resistant paper container.As a result, by combining the following methods, the inventor of the present invention We have completed the present invention by discovering that the object can be achieved.

That is, the present invention has a cylindrical body with a plastic film laminated on both sides of the paper, and a lid body with a plastic film laminated on the opposite side of the paper. I don't know. When inserting a skirt formed in the axial direction of the container with an inclination of 'ff: A slanted ring is brought into contact with the inner periphery of the skirt portion, the slanted ring, the skirt portion, and the end portion are received by the slanted wall of the support arm having an slanted wall on the inside, and the inner periphery of the slanted ring is placed on the outer periphery. A pressure-resistant paper container characterized in that an ultrasonic wave application horn having an inclined wall that engages with the ring and generates a wedge effect is brought into contact with an inclined ring, and the skirt portion and end portion are welded by applying ultrasonic waves. This is an ultrasonic welding method.

In the present invention, "made of paper" refers to a product that has physical properties such as easy crushability and combustibility that are not significantly different from pure paper products even if fibers such as plastic, powder, sheet, etc. are used in addition to pulp fibers. The main part is The plastic film refers to a resin film (approximately less than 20 μm) or sheet (<200 μm or more) made of a resin such as polyethylene that generates heat and melts when applied with ultrasonic waves, and is preferably a barrier film 8-. permeability (permeability and (
ri, 1 atm, temperature 23°C after reaching steady state.
(meaning the number of cc of gas permeated per square meter at a thickness of 1 mil in 24 hours at a relative humidity of 50 °C), which is sold, for example, under the trade name "Saran" Polyvinylidene chloride, polyamide, polyester, biaxially oriented polypropylene, polyvinyl chloride, ♂nyridine chloride-hinyl chloride copolymer, polyvinyl alcohol, ethylene-vinyl acetate sold under the trade name "EVAL" Included are films made of saponified copolymer resins, cellophane, nitrile resins sold under the trade name "Barex", and the like. A paper in which carbon dioxide gas barrier films are laminated on both sides has a greater carbon dioxide barrier effect than one in which a single film having a thickness corresponding to the total thickness of those films is used.

Further, the film may be a single layer or a laminate of two or more types. It is also possible to use a film in which a non-barrier film is laminated on one or both sides of a barrier film. This type of laminate film includes, for example, a polyethylene/polyvinylidene chloride/polyethylene laminate film sold under the trade name "Saranex". In this case, the polyethylene promotes heat sealing and does not significantly affect gas permeability. Furthermore, a film whose surface is coated with a barrier material can also be used. Examples of this type of film include films coated with polyvinylidene chloride resin called "Saran coat film" or "K coat film".

A cylindrical shape means that the cross section of the cylinder has substantially no straight parts and has an outwardly convex cross-sectional shape, such as a circle, an ellipse, or an oval shape.

Hereinafter, the present invention will be explained in detail with reference to all the drawings.

FIG. 1 is a partial cross-sectional view showing the cross-sectional structure of the upper half of the embodiment of the paper pressure-resistant container according to the present invention, and the arrangement of the inclined ring, the support arm, and the ultrasonic application horn. In the figure, a cylindrical body 1 made of paper is covered with plastic film 1a on both sides.
, ib, and a lid body whose inner and outer surfaces are laminated with plastic films 2d and 2e is attached to the X-axis of the fuselage 1 via the curved part 2b of the periphery of the spherical part 2a. North to. Or everyone. The skirt portion 2c extends outward with a slope of 1, and is press-fitted into the end of the body 1. Further, the end of the body 1 into which the lid 2 is press-fitted is firmly held against loads from above by a support arm 4 having an inclined wall 4a having the same inclination as the skirt part 2C on the inner side. Next, on the inner circumferential surface of the skirt portion 2c of the lid body 2, an outer circumferential portion 3 a s whose outer diameter coincides with the inner diameter of the skirt portion 2c in y and has the same slope as the slope of the skirt portion and an outer circumferential portion 3 a s with respect to the X axis is 20 to
Insert an inclined ring 3 having an inner peripheral portion 3be inclined at 45 degrees. When a circular ultrasonic applying horn 5 having an inclined wall 5a matching the slope of the inclined ring is lowered from above and strongly presses the slope of the inner circumferential portion 3b of the inclined ring 3, the skirt portion 2C is pressed against the body by a wedge action. It is firmly pressed against the end of 1. At this time, ultrasonic waves are applied for about 1 second to weld the outer peripheral surface of the skirt portion 2c and the inner peripheral surface of the end of the body 1. After welding is completed, the ultrasonic application horn is pulled up and the inclined ring 3 is taken out from the inner peripheral surface of the skirt portion 2c of the lid body 2, thereby completing the ultrasonic welding operation. When welding the bottom cover, the body is turned over and the R4Z cover and body are welded in an ultrasonic bath using the same method.

The first feature of the present invention is the skirt portion 2C of the lid body 2. ~ Beg. The ultrasonic wave application horn 5, the inclined ring 3, and the support arm 4 are used to generate a wedge effect. That is, the paper fuselage 1 is about 7k
When an internal pressure of about 2 g/2 d of drift is applied, the outer diameter of the fuselage 1 increases by about 1 inch. For example, the inner diameter of fuselage 1 is 7
If it is 4m7πφ, the increase in the diameter of the first coefficient is 0.74mm.
Therefore, the radius increases by 0.67 rnrn. A change in the inner diameter of this degree easily causes deformation when a force of this magnitude is applied. Therefore, if the welding period of the skirt portion 2C that connects the body 1 and the lid body 2 is 10 nm, the X axis of the skirt portion 2C The slope is 0°37/1°,
About 匈.

If there is a certain slope, it will be possible to press-fit the lid body 2 into the end of the body 1 within the expansion range of the body, and the lid body 2 will be
can be tightly fixed to the end of the body 1, and furthermore, this part can be firmly held from the outside of the body 1. On the other hand, if the inner circumferential portion 3b of the inclined ring 3 is inclined with respect to the X axis, the load applied vertically to the ultrasonic application horn 5 from above is divided into a vertical component and a horizontal component. The horizontal component of force presses the skirt portion 2ct tightly against the inner wall of the body 1, and by applying ultrasonic waves, the plastic films 1b and 2b laminated on the surfaces of the body 1 and the lid body 2 can be welded together. For example, the inclination angle of the inner circumference 3b of the inclination ring 3 is 60
If the vertical load applied by the ultrasonic applying horn 5 is 300 kg, a horizontal component force of 2601 ψ acts on the skirt portion 2C via the inclined ring 3, and the average surface pressure at this time is approximately 11 kg4wt. This makes it possible to maintain the surface pressure necessary for welding the lid body 2 to the cylindrical body 1.

A second feature of the present invention is that when a top cover and a bottom cover are attached to both ends of the body 10, they can be ultrasonically welded in the same operation.

BACKGROUND ART Conventionally, a skirt portion of a bottom lid of a container having an open end, such as a paper cup, is often welded by ultrasonic welding. In this case, since it is only one side, insert the supporting metal fitting for the lid inside the body, apply ultrasonic waves from the outside while tightening the two halves of the ultrasonic application horn, and apply ultrasonic waves to the adjoining plastic film. It is possible to weld them together, but if the lid is attached to both ends, the lid that will be welded later cannot be supported internally, and the internal pressure will be 10 Kg/Grn2)f.
However, by using the method of the present invention, the top and bottom covers can be welded to a cylindrical body uniformly and extremely well. Ultrasonic welding can be performed firmly and in a short time.

Next, preferred examples of materials to be used for each of the body 1, lid 2, and inclined ring 3 of the paper pressure container according to the present invention will be described.

The material for the body 1 is preferably laminated paper, which is made of pulp with a long fiber length, has a high tensile strength at break, and has a thickness of, for example, 300 μm and has plastic films laminated on both sides of the paper. Such a laminated paper is rolled double times into a tube shape, and the laminated plastic film surfaces are welded together by heat treatment to form a mold. 20
The 0 mm fuselage 1 can withstand an internal pressure of about 10 Kg//J2d and also a compressive load of 180 kg in the longitudinal direction. In experiments conducted by the present inventor, for example, when a 65 μm thick acrylic resin film "BAREX" (trade name, product of Vistron, Inc., USA) was used as the upper 8C plastic film, it was completely waterproof and waterproof. I was able to obtain the Sparya characteristics.

In manufacturing the body 1, it goes without saying that the cut ends of the laminated paper are sufficiently treated. ' A suitable material for the lid 2 is, for example, a lid shaped by hot-pressing a non-woven mat made by mixing plastic with pulp fibers before being made into paper, and laminating plastic films on both sides of the lid. be.

The material of the inclined ring 3 may be a metal such as aluminum or duralumin, but it may also be made of a plastic having a high melting point, such as a synthetic resin such as polyethylene terephthalate.

The slope of the skirt portion 2C of the lid body 2 relative to Xl1Illl varies slightly depending on the material of the paper of the body 1, but if it is enough to press the lid body 2 into place by tapping it lightly, it will be fine. I don't know. , preferably Kai. The front and back are suitable.

According to the above combination (C), if the ultrasonic application horn 5 is crimped through the inclined ring 3, received by the support arm 4, and welded, the body 1 and the lid 2 can be welded uniformly and firmly all around the circumference, resulting in a high It is possible to provide a pressure-resistant paper container with pressure-resistant strength, and it is valuable in meeting the current demand for use in food products such as beer.

[Brief explanation of drawings]

FIG. 1 is a partially sectional view showing an embodiment of the present invention. 1...Body, 1a, 1b...Plastic film, 2...Long body, 2a...Ball part, 2b...Curved part, 2C...Skirt part, 2a+28...Plastic film , 3... Inclined ring, 3a... Outer periphery, 3b... Inner periphery, 4... Support arm, 4a... Inclined wall, 5... Ultrasonic application horn, 5a... Slanted wall patent applicant Asahi Kasei Industries, Ltd. Figure 1

Claims (1)

[Claims] At the end of the cylindrical body, plastic film is laminated on both sides of the paper, and plastic film is laminated on both sides of the paper, extending around the outer periphery of the lid. It's hot. When inserting a skirt formed in the axial direction of the container with an inclination of A support arm having an inner slanted wall is made to receive the slanted ring, the skirt portion, and the end portion on the slanted wall of the support arm, and the outer periphery is engaged with the inner periphery of the slanted ring. An ultra-high pressure vessel made of paper, characterized in that a super wave application horn having an inclined wall that generates a wedge action when brought into contact with an inclined ring is brought into contact with an inclined ring, and the skirt portion and end portion are welded by applying ultrasonic waves. Sonic welding method