JP3864323B2 - Sealing apparatus and sealing method for thermoplastic resin container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method suitable for sealing a thermoplastic resin container having an opening used for containing contents containing a liquid substance and introducing the liquid.
[0002]
In recent years, in small electronic parts or electrical devices such as electrolytic capacitors, electric double layer capacitors, primary batteries, and secondary batteries, necessary members and liquids are accommodated in a thermoplastic resin container and used when introducing a liquid material. However, in order to achieve good sealing, further improvements in the sealing method and the sealing device are necessary. It is possible to provide a means for meeting the requirements.
[0003]
[Prior art]
For example, in a micro electrolytic capacitor, a capacitor element body and an electrolytic solution obtained by winding up an anode foil and a cathode foil from which conductive members are led out through insulating paper are accommodated in a thermoplastic resin container, and the electrolytic solution is introduced. The openings used for this are thermally sealed and sealed (see, for example, “Japanese Patent Application No. 6-153254”, “Japanese Patent Application No. 7-135116”, etc.).
[0004]
FIG. 7 is a cutaway side view of a main part showing a part of a thermoplastic resin container and a sealing device for explaining a conventional sealing method.
[0005]
In the figure, 1 is a thermoplastic resin container, 1A is an opening, 1B is a collar portion at the periphery of the opening, 2 is a heat welding heating member, 3 is a heat welding sealing portion, and 4 is a virtual color portion. In this case, PPS (polyphenylene sulfide) is often used as the thermoplastic resin.
[0006]
When the liquid or the like is accommodated in the container 1 and sealed, particularly when the liquid material has a high vapor pressure at the heat welding temperature of the container 1, the heating member 2 whose temperature has not increased is provided. Press the collar 1B to close the opening 1A,
(1) Temperature rise of the heating member 2 (2) Thermal welding (3) The heating member 2 is separated from the thermal welding sealing portion 3 through the process of lowering the temperature of the heating member 2, and one cycle sealing process is completed.
[0007]
By doing in this way, even if the vapor pressure of the liquid in the container 1 is increased and the internal pressure is temporarily increased, it is possible to achieve good sealing without the occurrence of pin holes.
[0008]
Even if the heating member 2 is kept in a state in which the temperature is constantly raised and is pressed against the collar portion 1B for sealing, the air in the container 1 as well as the thermoplastic resin in which the liquid vapor has melted is pushed away. Due to the ejection, stable sealing is impossible.
[0009]
In the sealing performed by the present applicant, when the opening 1A is 1 [mm] φ, the pressing force of the collar portion 1B by the heating member 2 is 2.5 [kg] from the start of heating to the end of welding. ] because by keeping to 3 (kg), even if the pressure in the container 1 becomes 200 [pressure], spitting the contents does not occur. Since the actual heat welding temperature is about 320 [° C.], the pressure in the container 1 is 10 [atm] or less, and good sealing is possible.
[0010]
[Problems to be solved by the invention]
Assignment 1
Usually, since the melting temperature of the PPS resin is about 290 [° C.], if the temperature of the heating member 2 is set to 290 [° C.] or higher, it is possible to perform heat-sealing and increase the temperature. Since heat sealing can be performed in a short time, it is better to raise the temperature of the heating member 2 in order to improve mass productivity.
[0011]
However, according to the experiment, when the temperature of the heating member 2 exceeds 350 [° C.], the mold release after the end of the thermal welding sealing, that is, the thermal welding sealing portion 3 and the heating member in the container 1 is performed. It was found that the separation from 2 was significantly worse.
[0012]
Assignment 2
In addition, the container 1 used by the present applicant is mainly made of PPS resin, and glass fibers are mixed in an amount of 30% by weight [%] to 40% by weight [%] in order to improve physical properties at high temperature. is doing.
[0013]
In general, since glass fiber has a high hardness and Vickers hardness of 640, even heating member 2 made of SKD-11 (Vickers hardness after quenching with JIS standard tool steel is 700) Since the surface becomes rough after about 10,000 use, it must be re-polished.
[0014]
Although it seems that there are many 10,000 times, if it is assumed that welding is performed once in 6 [seconds], replacement is required in about 18 [hours].
[0015]
Issue 3
Furthermore, as can be seen from FIG. 7, the surface of the heating member 2 that contacts the collar portion 1 </ b> B has a bowl shape, so that the heat-sealed sealing portion 3 is part of a spherical surface and protrudes from the surface of the container 1. It is in a state and its thickness is not uniform.
[0016]
Therefore, it is the portion of the heat-sealed sealing portion 3 that closes the opening 1A that the top surface of the container 1 comes into contact with another object and receives the impact first when handling the product. In particular, the portion is thinner than the other portions and is usually about 0.2 [mm], so that it easily cracks depending on the external force.
[0017]
In order to prevent this, for example, as shown by a broken line in FIG. 7, if the virtual collar portion 4 is actually provided, the heat-sealed sealing portion 3 can be protected, but the outer dimensions are increased. It cannot be avoided. It is well known that a surface mount type electronic component has a problem of a size of about 0.1 mm in the outer shape.
[0018]
Exercise 4
Furthermore, in order to facilitate the separation between the heat welded sealing portion 3 and the heating member 2, when the temperature in the heat welded sealed portion 3 is 300 [° C.] to 320 [° C.], the PPS resin Since the melting speed is slow, it is necessary to maintain the welding temperature for about 1.5 [seconds] (effective welding time) in the container 1 having the opening 1A of 1 [mm] φ. In the present specification, the heating time and effective welding time of the heating member 2 are referred to as welding time.
[0019]
In the initial experiment, the heating member 2 having a relatively large heat storage capacity was used, and the heating time and the effective welding time of the heating member 2 were set longer, but this requires a long welding time and a cooling time. Time / cycle becomes 7 [seconds].
[0020]
Based on the above-mentioned problems, in the present invention, a sealing device for a thermoplastic resin container, in particular, a method for improving the structure of a heat welding heating member, and sealing a thermoplastic resin container using the sealing device, In particular, by improving the temperature control of the heat welding heating member, it is easy to maintain and allows good sealing of the thermoplastic resin container, thereby improving the mass productivity as a whole.
[0021]
[Means for Solving the Problems]
In the present invention, a simple modification is made to the shape and structure of the heat fusion heating member to improve the releasability and protect the heat welding sealing portion in the container, and the pressure at the tip of the heat welding heating member A coating is formed on the heating surface to prolong the service life. Furthermore, in the sealing process using the heat welding heating member, the time required for the sealing process can be reduced by modifying the temperature control of the heat welding heating member. This shortens and greatly improves mass productivity as a whole.
[0022]
From the above, in the sealing device and the sealing method of the thermoplastic resin container according to the present invention,
(1)
For the color part (for example, the color part 11B) surrounding the opening (for example, the opening 11A) formed in a part of the thermoplastic resin container (for example, the thermoplastic resin container 11 such as PPS), from the start of welding to the end of welding, A pressure heating surface (for example, the pressure heating surface 13A) that presses and contacts with a constant pressure that can prevent the contents in the container from being blown back , closes the opening, and transfers heat from the heat generating portion to be welded and sealed. ) And a portion close to the pressure heating surface approximates the diameter of the color portion (for example, the diameter D1 of the color portion 11B) in order to increase the temperature of the central portion of the pressure heating surface and the vicinity thereof and lower the peripheral temperature. Or a heat welding / heating member (for example, heat welding / heating member 13) having a diameter reduced to a diameter (for example, a diameter reduced by forming the groove 13B), or
[0023]
(2)
In the above (1), the pressure heating surface is provided with a heat welding heating member covered with a TiN film , or
[0027]
By adopting the above means, the heating member is simply modified in its shape structure, and while maintaining good closure of the opening due to the pressure heating surface, the temperature distribution, that is, the central portion of the pressure heating surface and its vicinity Is kept at a high temperature, and at the periphery thereof, a low temperature is maintained, so that the pressing and heating surface of the heating member and the heat-sealed sealing portion can be satisfactorily separated, that is, the mold can be released well. . In addition, during the heating process, in order to prevent the contents of the container from being warmed and expanded and blown back, welding is always performed while maintaining a pressure of 2.5 kg to 3 kg. Existence causes more heat to be transferred to the center and becomes sufficiently higher than the melting temperature of the resin, and the molten resin flows into the opening, but the outer periphery of the pressure heating surface prevents heat conduction due to the presence of grooves. As a result, the resin melts slowly, and a pressure of 2.5 kg to 3 kg is supported on the outer periphery of the collar portion, so that no blow-back occurs even though the temperature at the center portion is sufficiently high. In order to produce such an effect, the groove, that is, the reduced diameter portion has an important role.
[0028]
In addition, surface roughness of the heating surface of the heating member is effectively suppressed, and if it is used in a normal manner, it can withstand 200,000 times of thermal welding, so that the life is extended 20 times that of the conventional method. Replacement is unnecessary for a long period of time, and the operating rate of the sealing device is improved, which can greatly contribute to mass production.
[0029]
Furthermore, it is also possible to realize a shape in which the heat-sealed sealed portion of the container is protected by simply modifying the shape structure of the heating surface of the heating member.
[0030]
Furthermore, by reducing the heat storage capacity of the heating member and carrying out appropriate temperature control, it was possible to halve the welding time and double the mass productivity.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 to FIG. 3 are principal part cut side explanatory views showing a sealing device and an electronic component in process essential points for explaining the first embodiment according to the present invention.
[0032]
In the figure, 11 is a thermoplastic resin container, 11A is an opening, 11B is a collar portion around the opening, 12 is a content containing a liquid material, 13 is a heat welding heating member, 13A is a pressure heating surface, and 13B is a groove. , 14 is a power source, 15 is a power switch, 16 is a cooling air blower, 17 is a heat-sealed sealed portion, 17A is a resin that flows into the opening 11A, D1 is a diameter of the collar portion 11B, and D2 is a heat-welding heating member 13 The diameter D3 indicates the diameter of the heating member 13 that has been reduced in diameter due to the presence of the groove 13B. Although not shown, at least the pressure heating surface 13A of the heat welding heating member 13 is covered with a TiN film formed by a PVD (physical vapor deposition) method, which will be described in detail later.
[0033]
Although the process of sealing the container 11 will be described with reference to FIGS. 1 to 3, the thermoplastic resin constituting the container 11 is again PPS.
[0034]
See Fig. 1 1- (1)
The opening 11A is covered by setting the container 11 containing the contents 12 containing the liquid material in the sealing device and pressing the pressing heating surface 13A of the heating member 13 against the collar portion 11B. At this stage, the power switch 15 is opened.
[0035]
See Fig. 2- (1)
The power switch 15 is closed, a current of about 50 [A] is passed through the heating member 13 to generate heat of about 300 [° C.] to 320 [° C.], and the heat is transmitted to the collar portion 11B to be melted.
[0036]
2- (2)
After the power switch 15 is opened, the heat welding is continued until the shape of the heat-welded / sealed portion 17 reaches a predetermined dimension due to the remaining heat of the heating member 13.
[0037]
See Fig. 3 3- (1)
When the shape of the heat-sealed sealing portion 17 reaches a predetermined size, cooling air is blown from the cooling air blower 16 to cool the heating member 13.
[0038]
3- (2)
At the stage where cooling of the heating member 13 is finished, the pressure heating surface 13A and the heat welded sealing portion 17 are separated, that is, released from the mold, and one cycle of the sealing process is completed.
[0039]
FIG. 4 is a timing chart showing a time transition of the sealing process described with reference to FIGS. 1 to 3. Referring to FIG. 4, a standard time transition of the sealing process in the present invention is shown. Clearly understandable.
[0040]
As described above, when sealing the container 11, in order to finish the processing in a short time, when heat welding at a high temperature, for example, 350 [° C.] or higher is performed, the press heating surface 13A and the heat sealing are sealed. Since the mold release from the portion 17 is deteriorated, it has been proved by experiments that the surface temperature of the pressure heating surface 13A is preferably maintained in the range of about 300 [° C.] to 320 [° C.].
[0041]
As is apparent from FIG. 1, the diameter D2 of the heating member 13, and thus the pressure heating surface 13A, must be closed to cover the opening 11A and completely cover the collar portion 11B, so that it is compared with the diameter D1 of the collar portion 11B. It is essential to make it bigger.
[0042]
When the pressure heating surface 13A having such a shape is brought into contact with the color portion 11B and melted, heat is absorbed by the color portion 11B at the portion of the pressure heating surface 13A in contact with the color portion 11B. Therefore, a temperature drop occurs.
[0043]
Here, when it is assumed that the groove 13B is not provided in the heating member 13, the heat in the heating member 13 is conducted to the entire surface of the pressure heating surface 13A having the diameter D2, and in such a state, When the heat is absorbed by the collar portion 11B, a temperature drop occurs only in the area corresponding to the diameter D1 in contact with the collar portion 11B on the pressure heating surface 13A. Therefore, the outer peripheral portion of D2-D1 In this case, there is no temperature drop and a high temperature state is maintained, which causes the mold release to deteriorate.
[0044]
In the heating member 13 according to the present invention, the groove 13B is provided in the vicinity of the tip of the heating member 13 so that the diameter is reduced to D3 and D3≈D1, so that heat conduction to the outer peripheral portion of D2-D1 is suppressed. Since the temperature rise at the time of heat welding is small, the releasability is greatly improved. Thus, the problem 1 is solved.
[0045]
By the way, at least the pressure heating surface 13A of the heating member 13 according to the present invention is covered with a TiN film having a thickness of, for example, about 2 [μm] formed by the PVD method, and this TiN film is formed on the pressure heating surface 13A. The surface roughening prevention has an excellent effect, and also contributes to good separation between the press-heating surface 13A and the heat-welded sealing portion 17, that is, to improve the releasability.
[0046]
The TiN film formed by the PVD method has a Vickers hardness of about 1700 to 2400, and when used as in the sealing process described above, the lifetime can withstand 200,000 thermal weldings. The service life was 20 times longer.
[0047]
Incidentally, since the present inventor conducted many experiments not only on the TiN film but also on other surface-modified films, some of them will be mentioned next.
[0048]
For example, a TiC film formed by a CVD (Chemical Vapor Deposition) method has a Vickers hardness of about 3800 to 4000 and is excellent in terms of mold release. When the TiC film is 100, the TiN film is 90%. Degree.
[0049]
However, the TiC film has poor resistance to thermal shock, and is repeatedly peeled off from the pressure heating surface 13A by repeated heating and cooling, and there is a problem for practical use at present. The TiN film has extremely good resistance to thermal shock, and no peeling occurs.
[0050]
Similarly, the WC film formed by the CVD method has a Vickers hardness of about 3800 to 4000 and is higher than the TiN film, but the mold release is inferior and cannot be used.
[0051]
As is apparent from the above, the TiN film is slightly inferior to the TiC film in terms of mold release, but has a very high resistance to delamination due to thermal shock. Therefore, at least the pressure heating surface 13A of the heating member 13 is currently made of TiN. Covering with a film is the optimum means for extending the life, and accordingly, Problem 2 has been solved.
[0052]
As described with reference to FIG. 7, in the present invention, the heating member 13 described with reference to FIGS. 1 to 3 has a heat-sealing seal because the pressing heating surface 13 </ b> A has a bowl shape. Of the portion 17, the portion covering the opening 11 </ b> A is thinner than the other portions, and when an external force is applied, there is a risk of cracking, but this changes the shape of the pressure heating surface 13 </ b> A. Can be solved easily.
[0053]
FIG. 5 is an explanatory view of the main part showing the sealing device and the electronic component at the main points of the process for explaining the second embodiment according to the present invention, and is the same as the symbols used in FIGS. The symbols shall represent the same part or have the same meaning.
[0054]
In the figure, (A) is a heat welding heating member of a sealing device and a cut side surface of the main part of the electronic component, (B) is a plane of the main part of the electronic component, 21 is a heat welding heating member, and 21A is a heat welding heating member. Reference numeral 21 denotes a pressure heating surface, and 22 denotes a heat-welded sealed portion.
[0055]
The heating member 21 used here is characterized in that the structure of the pressure heating surface 21A is provided with a deformed portion so as to generate a recess in the vicinity of the central portion of the heat-welded sealing portion 22, Thus, in the heat-sealed sealing portion 22 obtained, the vicinity of the center portion, that is, the portion having the lowest mechanical strength is recessed, so that external force can be prevented from being applied to the periphery of the recess.
[0056]
In FIG. 5A, since the central portion of the pressure heating surface 21A protrudes, as is apparent from the figure, the side cross section of the heat-welded sealed portion 22 has a concave central portion and is M-shaped. You will be caught.
[0057]
5 (B) and 5 (C), the heat seal portion 22 formed by the pressure heating surface 21A projecting in the center of the + symbol shape or S shape is shown. In this case, it is possible to achieve two purposes at the same time with an ultra-small electrolytic capacitor or battery that is difficult to indicate the electrical polarity or display by the manufacturer. Thus, Problem 3 has been solved.
[0058]
As shown in FIG. 4, the standard time transition of the sealing process is clarified. In the sealing process, the welding time obtained by adding the heating time of the heating member 13 and the effective welding time is 4. [Seconds], and the cooling time of the heating member 13 is further added, and it takes 7 [seconds] as a whole, which is one cycle of the sealing process.
[0059]
As described above, the heating member 13 according to the present invention has a long life and the time until replacement is greatly extended, so that alone, the mass productivity of electronic components and electrical devices is improved. If the time required for one cycle of the sealing process can be reduced, mass productivity can be improved directly.
[0060]
Therefore, the mass of the heating member 13 is reduced, and thus the heat storage capacity is reduced to about 1/2, for example, and the temperature rise and fall is accelerated, and in addition, fine temperature control, that is, heating power is turned on. -By performing the off control divided into a plurality of times, the time for one cycle of the sealing process is shortened to improve the mass productivity.
[0061]
FIG. 6 is a timing chart showing the time transition of the sealing process using the heat welding heating member with reduced heat storage capacity. In the following description of the sealing process, it is easy to understand with reference to FIGS.
[0062]
(1) When the heating member 13 is lowered and the pressing heating surface 13A is pressed against the collar portion 11B, the power switch 15 is turned on almost simultaneously.
[0063]
When the temperature of the heating member 13 rises, thermal welding starts. However, since the heat storage capacity of the heating member 13 is small, the temperature rises rapidly, and the temperature rises to 320 [° C.] from 0.3 [seconds] to 0.5 [seconds]. Has reached.
[0064]
{Circle around (2)} When the temperature of the heating member 13 reaches 320 [° C.], the power switch 15 is turned off, and thereafter, heat welding is continued by the residual heat of the heating member 13.
[0065]
(3) The temperature slightly decreases when 0.5 [seconds] elapses after the power switch 15 is turned off. Therefore, the power switch 15 is turned on again and the heating member 13 is energized.
[0066]
(4) After re-energizing, the power switch 15 is turned off in 0.2 [seconds], and then the heat welding is continued again with the remaining heat of the heating member 13, and in this way, the effective welding time is reduced. The temperature of about 320 [° C.] is maintained for a certain 1.5 seconds.
[0067]
5 As described above, when the welding time has passed 2.5 [seconds], the cooling air is blown from the cooling air blower 16 to cool the heating member 13. Although the cooling time is 2 [seconds], the heating member 13 may be raised when the time of 1.5 [seconds] elapses to release the mold. It should be noted that the specified amount of resin can be melted at high speed by reducing the heat storage capacity of the heating member 13 to increase the temperature , but the molten resin flowing into the opening 11A provides a strong seal. to do is not found to exist in the appropriate speed, to the amount of fusion and the melting rate of the resin to controls is effective intermittent heating.
[0068]
According to the sealing process, while ensuring an effective welding time of 1.5 [seconds], the welding time was reduced to 2.5 [seconds] and the cooling time was also shortened. The required time per cycle is 4.5 [seconds], and 55 [%] of production can be increased compared to the conventional 7 [seconds]. Thus, Problem 4 has been solved.
[0069]
The above-described control, particularly temperature control, is usually realized by providing a temperature sensor on the heating member 13 and forming a feedback loop so as to keep the detected temperature constant. Although there is a delay in heat conduction, the temperature stability is not improved at the expense of complexity and cost.
[0070]
In the present invention, an inexpensive and stable operation can be obtained by programming the on / off time of the heating power source using a simple sequencer.
[0071]
In the above-described embodiment, the description has been made mainly on the electrolytic capacitor. However, the present invention is not limited to this, and can be applied to other electronic components and electric devices to achieve excellent effects.
[0072]
For example, an electric double layer capacitor uses activated carbon for a positive electrode and a negative electrode, and an aqueous or nonaqueous electrolytic solution as an electrolytic solution is hermetically sealed in a container. Therefore, the present invention is effective. The battery (primary battery) uses an active material for the positive electrode and metallic lithium for the negative electrode, and a non-aqueous electrolyte solution is hermetically sealed in the container as the electrolyte solution. Furthermore, the nickel metal hydride battery (secondary battery) is the positive electrode. Since the hydrogen storage alloy is used for the negative electrode and nickel is used for the negative electrode and the caustic potash aqueous solution is hermetically sealed in the container as the electrolyte, the same effect as in the case of a capacitor or the like can be obtained.
[0073]
Incidentally, in an aluminum electrolytic capacitor, aluminum with an oxide film is used for a positive electrode and aluminum is used for a negative electrode, and an aqueous or non-aqueous electrolytic solution is hermetically sealed as an electrolytic solution in a container.
[0074]
【The invention's effect】
In the sealing device and the sealing method for a thermoplastic resin container according to the present invention, the collar portion surrounding the opening formed in a part of the thermoplastic resin container is pressed to close the opening and transmit heat. The shape and structure of the heat welding heating member that is welded and sealed is improved, the pressure heating surface is covered with a TiN film, and heat generation energy is intermittently supplied to the heat welding heating member multiple times. The predetermined welding temperature is maintained during the effective welding time.
[0075]
By adopting the above configuration, by making a simple modification to the shape structure of the heating member, the temperature distribution, that is, the central portion of the pressure heating surface, while maintaining good blockage of the opening due to the pressure heating surface And the vicinity thereof is kept at a high temperature, and the peripheral edge thereof is kept at a low temperature, so that the pressing and heating surface of the heating member and the heat-welded sealing portion can be satisfactorily separated, that is, the mold can be released well. be able to.
[0076]
In addition, surface roughness of the heating surface of the heating member is effectively suppressed, and if it is used in a normal manner, it can withstand 200,000 times of thermal welding, so that the life is extended 20 times that of the conventional method. Replacement is unnecessary for a long period of time, and the operating rate of the sealing device is improved, which can greatly contribute to mass production.
[0077]
Furthermore, it is also possible to realize a shape in which the heat-sealed sealed portion of the container is protected by simply modifying the shape structure of the heating surface of the heating member.
[0078]
Furthermore, by reducing the heat storage capacity of the heating member and carrying out appropriate temperature control, it was possible to halve the welding time and double the mass productivity.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory side view of a principal part showing a sealing device and an electronic component in a process essential point for explaining a first embodiment according to the present invention.
FIG. 2 is an explanatory side view of a principal part showing a sealing device and an electronic component in a process essential point for explaining the first embodiment according to the present invention;
FIG. 3 is an explanatory side view of a principal part showing a sealing device and an electronic component in a process essential point for explaining the first embodiment according to the present invention;
FIG. 4 is a timing chart showing a time transition of the sealing process described with reference to FIGS. 1 to 3;
FIG. 5 is a main part explanatory view showing a sealing device and an electronic component in process key points for explaining a second embodiment according to the present invention;
FIG. 6 is a timing chart showing a time transition of a sealing process using a heat welding heating member with a reduced heat storage capacity.
FIG. 7 is a cutaway side view of a main part showing a part of a thermoplastic resin container and a sealing device for explaining a conventional sealing method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Thermoplastic resin container 11A Opening 11B Color part 12 of opening periphery Contents 13 containing liquid material Heat welding heating member 13A Press heating surface 13B Groove 14 Power supply 15 Power switch 16 Cooling air blower 17 Heat welding sealing part 17A Opening 11A The resin 21 that has flowed into the inside 21 Heat welding heating member 21A Press heating surface 22 Heat welding sealing portion D1 Diameter D2 of the collar portion 11B Diameter D2 of the heat welding heating member 13 Diameter of the heating member 13 reduced in diameter due to the presence of the groove 13B

Claims (2)

The collar part surrounding the opening formed in a part of the thermoplastic resin container is pressed against the collar part at a constant pressure that can prevent the contents in the container from blowing back from the start of welding to the end of welding. The pressure heating surface that closes the opening and transfers heat from the heat generating portion to weld and seal, and pressurizes to increase the temperature of the central portion of the pressure heating surface and the vicinity thereof and to lower the temperature of the peripheral edge. A sealing device for a thermoplastic resin container, comprising a heat welding heating member having a diameter close to the diameter of a collar portion at a portion close to a heating surface. 2. A sealing device for a thermoplastic resin container according to claim 1, further comprising a heat welding heating member having a pressure heating surface covered with a TiN film.

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