JP2003341605A - Seal material welding method and device for plastic container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal material welding method and device which easily handle different mouth sizes and shapes with little uneven welding in a peripheral direction. <P>SOLUTION: This welding device welds a plastic sheet like seal material S on the opening end face B3 of the mouth B1 of a plastic container B, and is provided with a wave guide tube or an applicator 1 formed with a hole 4 having a slightly larger diameter than that of a container cap on its peripheral wall with an entrance 2 on both ends, a metal reflector 8 placed in the wave guide tube or the applicator 1 in parallel with a face containing the hole 4 peripheral edge in the range of the hole 4 peripheral edge, a supporting body 9 supporting the container so as a capped opening maintains the cap top face and the metal reflector positioned roughly in parallel and with a predetermined interval, and a microwave injecting device for injecting the travelling wave of the microwave from the entrance 2 on both ends. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for welding a sealing material for a plastic sheet to the mouth of a plastic container.

[0002]

2. Description of the Related Art As a device for welding and attaching a lid portion of a plastic material to the mouth portion of a plastic container, there is disclosed in Japanese Patent Laid-Open No.
What is disclosed in 294707 is known. In this device, a container with a lid is housed in an applicator called a casing, and high frequency is applied to heat and weld a lid portion which is a dielectric.

On the other hand, a method of dielectrically heating a linear plastic material using microwaves is disclosed in Japanese Patent Laid-Open No. 60-240094.
Is disclosed in. According to this method, the linear plastic material running through the waveguide is dielectrically heated by the standing wave generated in the waveguide.

[0004]

However, the above-mentioned two known techniques are not suitable for welding the sealing material to the mouth of the plastic container.

First, in Japanese Patent Laid-Open No. 4-294707, since heating is performed by high frequency dielectric, an electrode is required, and the high frequency dielectric device having the electrode must be positioned so as to be in close contact with the container. As a result, the dielectric device must match the shape and size of the lid. This means that even if the shape and size of the lid part is slightly changed, the dielectric device must be changed. Further, the container body to which the lid is attached is not suitable for a container already filled with the contents because it is internally supported by the support member in a state where the contents are not filled.

Next, in JP-A-60-240094, in order to weld a sealing material or a lid member to the mouth of a container,
It is unclear what to do and is not suitable. or,
Even if it is possible to place the container in the waveguide,
Since the microwave is a standing wave, the welding strength of the sealing material varies depending on the circumferential position of the mouth portion, resulting in uneven welding. From this point of view, this device is not suitable for welding the sealing material to the mouth of the container.

In view of such circumstances, the present invention can cope with a slight change in the shape or size of the mouth portion or the cap, and can weld the sealing material without uneven welding at the circumferential position of the mouth portion. It is an object to provide a method and a device.

[0008]

<Solving Material Welding Method> In the sealing material welding method according to the present invention, a plastic sheet-like sealing material is welded to the opening end face of the mouth of a plastic container.

In such a sealing material welding method, according to the present invention, a plastic cap is capped on the opening portion with the sealing material placed on the opening end face of the opening portion, and a waveguide having an entrance opening at both ends is provided. An opening with a cap for the container is arranged in a hole formed in the peripheral wall of the applicator with a diameter slightly larger than the cap of the container, and in a range extending to the peripheral edge of the hole, substantially parallel to the surface including the peripheral edge. The position of the container is set so that the metal reflection plate arranged in the waveguide or the applicator and the upper surface of the cap are spaced from each other by a predetermined distance, and a traveling wave of microwaves is incident from the entrance ports at the both ends. To do.

According to the present invention which has undergone such a procedure, since the microwave is a traveling wave, the microwave intensity is substantially uniform at any position in the incident direction, but the edge of the hole and the metal reflection Due to the reflection of microwaves from the plate and the transmission of microwaves in the inner area of the hole, the microwaves are concentrated only in the peripheral area of the opening end face of the mouth and the dielectric heating is strongly performed in the peripheral area. Here, the sealing material is securely welded and sealed in the circumferential direction.

In the present invention, if the cap is capped on the mouth so as to clamp the sealing material against the opening end surface of the mouth of the container with a predetermined pressure, the sealing is more reliably performed.

<Seal Material Welding Device> With regard to the device for carrying out the above seal material welding method, the present invention has an entrance at both ends and a hole portion having a diameter slightly larger than the diameter of the cap of the container on the peripheral wall. The formed waveguide or applicator, a metal reflection plate disposed in the waveguide or applicator in a range extending to the peripheral edge of the hole in parallel with the surface including the peripheral edge, a cap upper surface and metal reflection It is provided with a support body for supporting the container by arranging the capped mouth portions so that the plates are parallel and keeping a predetermined interval, and a microwave incidence device for injecting a traveling wave of microwaves from the incidence ports at the both ends. Is characterized by.

In such an apparatus, the container having the sealing material at the mouth is supported by the support so that the mouth is at the position of the hole, and in this state the entrance of the waveguide or applicator. The traveling wave of the microwave is incident from. As described above, the microwave is concentrated around the opening end face of the mouth portion, and the sealing material is well sealed.

In the present invention, it is preferable that at least one of the metal reflection plate and the support is movable so that the distance between the upper surface of the cap and the metal reflection plate can be adjusted. By adjusting the interval, the reflection strength of the microwave can be adjusted and the welding strength of the sealing material can be made appropriate.

If the support body is formed as a metal box body capable of accommodating the entire container, the box body can prevent the microwaves transmitted inside the mouth from leaking to the outside.

It is desirable that the container of the support can be exchanged, and the sealing material can be welded by sequentially exchanging a plurality of containers.

If a plurality of supports are provided and the container supported by each support can be moved sequentially so that the cap-equipped opening is located at the position of the hole of the waveguide or applicator. The welding of the sealing material can be automated for a plurality of containers.

In the waveguide or applicator, if the size and shape of the hole are variable, it is possible to easily cope with changes in the shape and size of the container and its mouth. it can.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a waveguide or an applicator (hereinafter referred to as an applicator), and both end openings of a metal tubular body extending in the lateral direction are microwave entrances 2. The bottom wall 3 of the applicator 1 has a container B
A hole portion 4 having an inner diameter slightly larger than the outer diameter of the cap C attached to the mouth portion B1 is formed. A support rod 6 is detachably attached to the upper wall 5 of the applicator 1 by a screw 7, and a metal reflection plate 8 is supported at the lower end of the screw 7. The metal reflection plate 8 is substantially parallel to the surface including the peripheral edge of the hole 4, that is, the surface of the lower wall 3, and has an outer diameter slightly larger than the inner diameter of the hole 4.

On the outer surface of the lower wall 3 of the applicator 1,
A box-shaped metal support 9 is attached. Although not shown, the support 9 has an openable and closable door on the side surface or the bottom surface thereof, and allows the container B to enter and exit. The support 9 supports the container B so that the cap C is at a height position such that the cap C enters the hole 4 of the applicator 1 when the container B is supported on the bottom surface.

The container B is made of plastic. For example, as shown in FIG. 2, the plastic cap C having a screw portion C2 screwed into a screw portion B2 formed at the mouth portion B1 of the container B is the above-mentioned. It is adapted to be worn on the mouth portion B1. After the contents of the container B are filled in the mouth B1, the sheet-like sealing material S made of plastic is used.
Is placed on the open end surface B3 of the mouth portion B1, and then the cap C is capped. As will be described later, the sealing material S is welded to the opening end face B3 in a state where the cap C is capped, and seals the mouth portion B1. Therefore, the sealing material S is the opening end surface B of the mouth.
Only weld to No. 3 and not to Cap C,
The surface on the side of the cap C is selected or processed with a plastic material therefor.

In the apparatus of the present embodiment, the sealing material is welded to the container opening portion in the following manner.

First, the sealing material S is arranged on the opening end surface B3 of the mouth B1 of the container B filled with the contents, and the cap C is capped on the mouth B1 from above. At that time, it is preferable that the cap C sandwiches the sealing material S with the opening end surface B3 with a pressure suitable for welding and sealing. This pressure depends on the set seal strength, sealant and mouth material,
It is determined by various conditions such as microwave intensity.

Next, the container B is attached to the box-shaped support 9
Place it inside. The mouth portion B1 of the container B with the cap C is
It is positioned so as to enter into the hole 4 of the applicator 1 from below, and the distance between the upper surface of the cap C and the metal reflection plate 8, that is, the distance between the seal material S and the metal reflection plate 8 is kept at a predetermined value. The sealing material S and the metal reflection plate 8 are parallel to each other. The above interval is appropriately changed and set by changing the tightening condition of the screw 7 for holding the support rod 6 or the length of the support rod 6 itself.

After the container B is set at the predetermined position in this way, the traveling wave of the microwave is made incident from the incident ports 2 on both sides as shown by an arrow P. Since this microwave is a traveling wave, its intensity in the traveling direction is uniform.

The microwave is applied to the upper wall 5 of the applicator.
While advancing in the P direction while reflecting between the metal reflection plate 8 and the lower wall 3, at that time, as shown in FIG. Because of the close distance between
The reflection Q is particularly strong. The strong reflection Q is obtained in the vicinity of the peripheral edge, that is, in the donut-shaped region X including the opening end face B3 of the mouth B1 of the container B. Inside the region, that is, inside the mouth portion B (inward in the radial direction), the microwaves are transmitted as shown by the arrow R, so that the intensity thereof is low. The intensity of this microwave is shown in FIG. 4 in relation to the radial position of the mouth. In this way, the microwave becomes strong only in the donut-shaped region X including the opening end face B serving as the sealing surface, and is low inward. Therefore, the dielectric heating is made strong only at the seal surface and rises to a temperature sufficient for the seal, and the temperature rise inside is small. Since the sealing material S is pressed by the cap C, the mouth portion B
It can be sufficiently welded to the peripheral end face B3 of No. 1.

The invention is not limited to the illustrated embodiment,
Various changes are possible. For example, a metal reflector allows the distance to the bottom wall of the applicator to be changed,
It is preferable that the outer diameter and the outer shape of the metal reflection plate can be changed together according to the hole diameter and the hole shape of the hole portion of the lower wall. By doing so, various mouth diameters and mouth shapes can be accommodated. For that purpose, it is also a measure to make the peripheral edge of the hole removable so that the metallic reflector is directly supported by this peripheral edge. Of course, at this time, the member supporting the metal reflection plate should not have a great influence on the reflection of the microwave.

Further, it is preferable that a part of the support can be opened and closed so that the container can be exchanged, but in addition to that, a plurality of supports are provided, and these are sequentially applied to the container at the mouth thereof. It is desirable that the welding device can be moved so as to bring it to the position of the hole portion, and the welding device can be automated.

In addition, when it is desired to provide a portion having a low welding strength in a part of the circumferential direction to facilitate the peeling of the sealing material from this portion, the metal reflection plate is cut out in the corresponding portion. Is also possible.

<Embodiment 1> The cross section perpendicular to the incident direction of microwaves has a square tubular shape, and the dimensions thereof are 110 × 5.
Using a 5 × 120 mm applicator, a sealing material was placed on the mouth of the container and a cap was capped, and then the sealing material was welded to the opening end face of the mouth. Here, the material of the mouth of the container has a laminated resin constitution of "low density polyethylene / ethylene / vinyl alcohol copolymer / low density polyethylene". The diameter of the metal reflector is slightly larger than the outer diameter of the cap, 30 mm.
The distance between the cap and the top surface was set to 2 mm and 6 mm. The microwave was incident at 500 W for 30 seconds.
In order to determine the condition of the welded seal, the surface temperature of the sealing material was measured at four positions in the circumferential direction of the mouth. Note that the temperature measurement was performed during the cooling of the sealing material about 50 seconds after the end of microwave irradiation for convenience.

Here, the material of the sealing material is a laminated resin composition "oxygen gas barrier resin / low density polyethylene / polyurethane / cellophane / a resin mixture of polypropylene and high density polyethylene / high density polyethylene / polyester / olefin resin including styrene resin. Resin mixture (side welded to the mouth of the container) ”.

<Embodiment 2> The cross section perpendicular to the direction of incidence of microwaves has a square tubular shape, and its dimensions are 110 × 5.
Using a 5 × 120 mm applicator, a sealing material was placed on the mouth of the container and a cap was capped, and then the sealing material was welded to the opening end face of the mouth. The metal reflector had a diameter of 38 mm, which was slightly larger than the outer diameter of the cap, and the distance from the upper surface of the cap was set to 4 mm. Microwave is 1700W, 30
It was incident for a second. The measurement is the same as in Example 1.

1) Distance between metal reflector and cap: 2 mm
(Example 1) The temperature was between 60 and 70 ° C. at all measurement positions, indicating a good seal.

2) Distance between metal reflector and cap: 6 mm
(Example 1) The temperature was between 55 and 65 ° C. at all measurement positions, indicating a good seal.

3) Distance between metal reflector and cap: 4 mm
(Example 2) The temperature was between 60 and 70 [deg.] C. at any measurement position, indicating a good seal.

As can be seen from this measurement, in order to obtain the best welded seal, it is desirable to keep the metal reflector at a predetermined distance from the cap.

[0038]

As described above, according to the present invention, the opening portion is arranged at a predetermined distance from the metal reflection plate in the hole portion of the waveguide or the applicator which is formed so as to be fitted to the opening portion with the lid of the container. Therefore, the traveling wave of the microwave is concentrated and reflected in the peripheral area of the hole between the metal reflection plate and the wall surface of the waveguide or the applicator, and thus effectively seals at the peripheral edge of the mouth. Material is welded by dielectric heating. Moreover, since the microwave penetrates and is absorbed inward of the container, the heating of the central region of the mouth is small, so that the sealing material is not deformed such as wrinkles. Further, since the microwave is a traveling wave, the intensity of the microwave in the traveling direction is uniform everywhere, and it is possible to suppress variations in welding at the circumferential position of the mouth portion.
Further, more preferably, by rotating the container, the variation in welding becomes smaller.

Thus, when the sealing material is welded to the mouth portion in a state where the container filled with the contents is capped, the sealing material can be made of only plastic without using metal, so that foreign matter The metal can be easily found by the metal detection and inspection device, and the defective product can be surely judged.

Further, according to the present invention, it is possible to easily cope with changes in the size and shape of the mouth portion and the cap of the container, which leads to simplification of the apparatus.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an apparatus according to an embodiment of the present invention, showing a state of supporting a container.

2 is a partially cutaway front view of the container of FIG. 1 in a separated state of a sealing member and a cap.

3 is a sectional view of the cap of FIG. 1 and FIG. 2 when the container is in place in the device of FIG. 1;

FIG. 4 is a front sectional view of a mouth portion in the center, a top view of the mouth portion below the mouth portion, and a microwave intensity distribution in the mouth portion above the mouth portion.

[Explanation of symbols]

1 Applicator 2 entrance 3 peripheral walls (lower wall) 4 holes 8 metal reflector 9 Support B container B1 mouth B3 Open end face C cap S seal material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29L 22:00 B29L 22:00 F term (reference) 3E049 AB01 DB05 3K090 AA01 AA15 AB07 BB18 CA01 PA01 4F211 AA04E AA07 AA11 AA13 AA19E AA31 AD05 AD20 AD32 AG07 AH55 TA01 TC07 TC16 TD11 TH02 TH06 TH18 TJ30 TN26

Claims (8)

[Claims] 1. A method of welding a plastic sheet-like sealing material to an opening cross section of a mouth of a plastic container, wherein a plastic cap is attached to the mouth while the sealing material is arranged on the opening end face of the mouth. Then, the mouth portion with the cap of the container is arranged in the hole formed in the peripheral wall of the waveguide or the applicator having the entrances at both ends with a diameter slightly larger than the cap of the container, and extends to the periphery of the hole. In the range, the position of the container is set so that the metal reflecting plate disposed in the waveguide or the applicator and the upper surface of the cap are substantially parallel to the surface including the peripheral edge, and from the incident ports at the both ends. A method for welding a sealing material for a plastic container, characterized in that a traveling wave of a microwave is incident. 2. The method for welding a sealing material for a plastic container according to claim 1, wherein the cap is capped on the opening so as to press the sealing material against the opening end surface of the opening of the container at a predetermined pressure. . 3. A device for welding a plastic sheet-like sealing material to an opening end face of a mouth of a plastic container, wherein a hole having an entrance at both ends and a diameter slightly larger than the diameter of the cap of the container is formed on the peripheral wall. Waveguide or applicator, a metal reflector disposed in the waveguide or applicator in a range extending to the peripheral edge of the hole in parallel with a surface including the peripheral edge, a cap upper surface and a metal reflector And a support for supporting the container by locating the cap-equipped mouth so that they are substantially parallel to each other and maintaining a predetermined distance, and a microwave injection device for injecting a traveling wave of microwaves from the entrances at both ends. A sealing material welding device for plastic containers. 4. The welding of a sealing material for a plastic container according to claim 3, wherein at least one of the metal reflection plate and the support is movable so that a gap between the cap upper surface and the metal reflection plate can be adjusted. apparatus. 5. The sealing material welding device for a plastic container according to claim 3, wherein the support is formed as a metal box body capable of accommodating the entire container. 6. The sealing material welding device for a plastic container according to claim 3, wherein the container of the support is replaceable. 7. A plurality of supports are provided, and the container supported by each support can be sequentially moved so that the mouth part with the cap comes to the position of the hole of the waveguide or the applicator. The sealing material welding device for a plastic container according to any one of claims 3 to 6. 8. The apparatus for welding a sealing material for a plastic container according to claim 3, wherein the size of the hole and the shape of the waveguide or the applicator are variable.