JP2001278221A - Heat sealing method and heat sealing device - Google Patents

Abstract

(57) [Problem] To provide a heat sealing method and a heat sealing apparatus capable of obtaining a high-strength seal portion and shortening a manufacturing time (lead time), and reliability of the seal portion. It is an object to improve the manufacturing efficiency of the seal part. SOLUTION: The joining surfaces of a pair of sheets having a resin layer provided on the joining surface are aligned with each other, and the back surfaces of the pair of sheets are sandwiched while being heated, thereby melting the resin layer at the heated portion. In the heat sealing method for tightly sealing between bonding surfaces of sheets, a step of holding a heated portion by heating with a heater bar for a certain period of time, and immediately after this heating holding step, the heated portion is cooled by a cooling bar for a certain period of time. And a step of clamping.

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 heat-sealing a pack material used for sealing small electronic components such as batteries.

[0002]

2. Description of the Related Art In recent years, for example, in the field of home electric parts and computers, there has been a tendency to lower prices, so that cost reduction of production facilities and shortening of lead time have been actively promoted. At the same time, high functionality is being promoted, and products are required to maintain and improve quality more than ever under severe conditions of high functionality and low cost.

[0003] Under such circumstances, the maintenance and improvement of a higher level of safety has become a proposition, especially for products that are likely to cause danger during use due to the function and structure of the product. For example,
The same can be said for the seal density, strength, and the like of the outer package in the battery. In this type of battery, both electrodes, a separator, an electrolyte, and the like are sealed by a metal case or an aluminum pack. In particular, liquids and semi-solid substances containing electrolytes should not be leaked to the outside since they will adversely affect other parts and the like when they flow out.

Conventionally, when an aluminum pack is used for the exterior, the sealing method is as follows: the joining surfaces of a pair of sheets provided with a resin layer on the joining surface are joined together, and the joining surfaces are sandwiched between heaters. A method of melting and sealing resin layers in contact with each other has become common. This sealing method is roughly classified into a heat sealing method using a constant heater and a heat sealing method using an impulse heater.

FIG. 10 is an explanatory view showing a procedure of a conventional heat sealing method using a constant heater. In this conventional heat sealing method, the bonded portion 1a of the aluminum pack material 1 is sandwiched between upper and lower heater bars 3a and 3b, which always maintain a constant temperature, with a constant force and a constant time. Thereby, the resin layer of the bonding part 1a is melted. Thereafter, the heater bars 3a and 3b were separated, and natural cooling was performed, whereby a pack material 5 in which the bonded portion 1a was tightly sealed was obtained.

[0006]

[Problems to be Solved by the Invention] In the field of electronic components and computers, safety is becoming more and more important as competition for price reduction is accelerated. In other words, there is a demand for improving the reliability of products at the same time as improving the efficiency of the manufacturing process. However, in the conventional heat sealing method, after the resin layer is melted by the upper and lower heater bars, the heater bar is released and the heated portion is naturally cooled, so that the cooling state of the heated portion becomes non-uniform and the shrinkage ratio varies. Was locally generated and wrinkles sometimes occurred. If such wrinkles occur in the seal portion, the contact surface becomes uneven and reduced, which is a factor of reducing the seal strength.
Further, in order to improve the sealing strength, various considerations have been made on the pressing force of the heater bar, the width of the sealing portion, and the like. However, a highly reliable heat sealing method has not been realized. The present invention has been made in view of the above circumstances, and provides a heat sealing method and a heat sealing apparatus capable of obtaining a high-strength seal portion and shortening a manufacturing time (lead time). It is an object of the present invention to improve the reliability of the seal part and the manufacturing efficiency of the seal part.

[0007]

According to a first aspect of the present invention, there is provided a heat sealing method, comprising: joining a pair of sheets provided with a resin layer on a joining surface; In a heat sealing method in which the back surfaces of the pair of sheets are sandwiched while being heated while being heated, the resin layer at the heated portion is melted and the bonding surfaces of the sheets are tightly sealed to each other. And a step of immediately after the heating and holding step, and a step of holding and holding the heated portion by cooling with a cooling bar for a certain time.

In this heat sealing method, the heated portion is held while being heated by the heater bar for a certain period of time, and immediately after this heating and holding, the heated portion is held while being cooled by the cooling bar for a certain period of time. As a result,
The wrinkles of the seal portion due to the uneven shrinkage that occur when the natural cooling is performed without the pressurization are suppressed by the pressurization. Further, at this time, the re-solidified resin is easily cooled uniformly by being forcibly cooled at the same time, which also suppresses the generation of wrinkles. This eliminates wrinkles on the contact surface, eliminates contact between the joint surfaces with a uniform contact surface, and increases the strength of the seal portion.

According to a second aspect of the present invention, in the heat sealing method, the pressing force of the holding by the cooling bar is larger than the pressing force of the holding by the heater bar.

In this heat sealing method, the pressing force at the time of holding by the cooling bar becomes larger than the pressing force at the time of holding by the heater bar, and a large pressing force is applied in accordance with the hardness of the resin layer which increases with cooling. It acts on the surface and the generation of wrinkles is more effectively suppressed.

The heat sealing method according to a third aspect of the present invention is characterized in that the heating and the cooling are sandwiched while applying tension to the area of the sheet including the heating portion.

In this heat sealing method, tension is applied to the area of the sheet including the heated portion, and the heated portion is appropriately pulled at the time of holding by heating and at the time of holding by cooling, thereby preventing generation of wrinkles due to loosening of the sheet. .

The heat sealing method according to a fourth aspect is characterized in that the switching time from the end of the heating and holding process to the start of the cooling and holding process is 2 seconds or less, more preferably 1.5 seconds or less.

In this heat sealing method, the cooling holding process is started with a switching time shorter than at least 2 seconds from the end of the heating holding process. When the switching time is longer than 2 seconds, the resin layer starts to shift to a solidified state similar to the natural cooling state. That is, wrinkles easily occur. Therefore, before the transition to the solidified state due to the natural cooling state starts, by starting the cooling sandwiching step, the generation of wrinkles is more effectively suppressed.

According to a fifth aspect of the present invention, in the heat sealing method, a width of a seal portion which is tightly sealed along the heater bar and the cooling bar is 3 mm or more and 10 mm or less.

In this heat sealing method, the seal portion having a stable strength can be obtained because the width of the seal portion is 3 mm or more and 10 mm or less. That is, if the thickness is less than this range, a sufficient adhesion area cannot be obtained, and sufficient strength is not exhibited in the seal portion after the resin layer is solidified. Also,
If it is more than this range, it will not be suitable as a seal portion when forming a small hermetic container such as a battery.

According to a sixth aspect of the present invention, in the heat sealing method, the pressing force for clamping by the heater bar is at least 0.1%.
It is characterized by being 96 Mpa or more.

In this heat sealing method, when the pressing force of the holding by the heater bar is at least 0.196 Mpa or more, the joint surfaces can be uniformly and closely contacted when the resin layer is melted. That is, if it is less than this value,
Unevenness is likely to occur in the close contact state of the joining surface, and wrinkles are likely to occur. Such a situation will be eliminated.

In the heat sealing apparatus according to the present invention, the joining surfaces of a pair of sheets provided with a resin layer on the joining surfaces are aligned with each other, and the back surfaces of the pair of sheets are sandwiched while being heated. In a heat sealing device that melts the resin layer at a heated location and tightly seals the bonding surfaces of the sheets, a pair of heater bars that sandwich the heated location while heating the heated location for a predetermined time, and heating and clamping by the heater bar And a pair of cooling bars that sandwich the heated portion while cooling the heated portion for a predetermined time after the process is completed.

In this heat sealing device, the heated portion immediately after the resin layer is melted is cooled and sandwiched by the cooling bar, so that it is rapidly cooled while being pressurized. Thereby, conventionally, wrinkles due to uneven shrinkage of the resin layer after melting, which were caused by allowing the molten portion to cool naturally by leaving it,
It can be forcibly deterred. Therefore, the bonding surfaces of the sheets are tightly adhered to each other with a uniform close contact surface without wrinkles, and the loss of the close contact portion caused by the occurrence of wrinkles is eliminated. Is obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a heat sealing method and a heat sealing apparatus according to the present invention will be described below in detail with reference to the drawings. 1 is an external perspective view of the heat sealing device according to the present invention, FIG. 2 is an enlarged perspective view of a main part of the heat sealing device shown in FIG. 1, and FIG. 3 is a handling jig set on the slide unit shown in FIG. FIG. 4 is an enlarged sectional view of an end portion of the pack material to which tension is applied by a side tension unit, and FIG. 5 is a plan view of the heat-sealed pack material.

The heat seal device 11 is a device frame 1
Each work unit is disposed on the upper surface of the work unit 3. At the center of the upper surface of the device frame 13, a belt-type transport unit 7 having a guide rail 5 extending from the front surface (lower left in FIG. 1) toward the back of the device frame 13 (upper right in FIG. 1) is provided.

As shown in FIG. 2, a slide unit 9 is provided at the front end of the transport unit 7. The slide unit 9 has a slide table 11 serving as a base. The slide table 11 is fixed to a belt 5 a movable on the upper surface of the guide rail 5 of the transport unit 7, and can reciprocate between the front and the back of the apparatus frame 13 along the guide rail 5.

On both side surfaces of the slide table 11, side tension units 13 are provided. The side tension unit 13 has a side tension slide 15 serving as a base. The slide 15 for side tension is movably mounted on a support plate 16 protruding from a side portion of the slide table 11.
1 can be moved in the approaching / separating direction (the direction of arrow a). The movement in the approaching / separating direction is performed by, for example, the side tension unit 13 and the side tension slide 1.
5, a compression spring is arranged, and a slide cam 17 is brought into contact with the outer surface of the side tension slide 15,
This can be achieved by rotating the slide cam 17 to displace the sliding contact surface of the side tension slide 15 that contacts the outer periphery of the slide cam 17.

A clamper 21 is provided above the side tension slide 15 so as to be swingable about a rotation shaft 19 in the same direction as the guide rail 5. At the front end of the clamper 21, a first cushioning material (silicon rubber or the like) 23 shown in FIG. Further, a second cushioning material (silicon rubber or the like) 25 that is in contact with the first cushioning material 23 is fixed to one end edge of the upper surface of the side tension slide 15. The clamper 21 is swung about the rotation shaft 19 and the first cushioning material 2
3. In a state where the second cushioning members 25 are in pressure contact with each other, rotation is prevented by a locking means (not shown).

In the vicinity of the clamper 21 of the slide table 11, there are formed left and right long holes 27 along the first buffer material 23 and the second buffer material 25. The jig mounting portion 29 is located at the center of the slide table 11 between the left and right long holes 27.

A handling jig 31 shown in FIG. 3 is set on the jig mounting portion 29. Handling jig 31
Is a rectangular base 33, and a lid 37 that is rotatable on one side of the base 33 around a fixing pin 35 in the side direction.
It is composed of On the upper surface of the base 33, a buffer plate (silicon rubber or the like) 39 is attached. Also, this buffer plate 3
On the surface of the lid 37 facing the surface 9, a trapezoidal cushioning material (silicon rubber or the like) 41 whose central portion is curved in a convex shape is fixed. The handling jig 31 places a pack material (work) 43, which is a pair of sheets, on a buffer plate 39 and rotates the lid 37 in the direction of the base 33 so that the center of the work 43 is buffered. They can be pressed and held between each other to be held. The work 43 is provided with a resin layer on the joint surface of the pair of sheets, as in the related art.

The handling jig 31 has a plurality of fixing pins 45 protruding from the jig mounting portion 29 of the slide table 11 in fixing holes (not shown) formed in the lower surface of the base 33.
Is inserted into the slide table 11 so that the movement in the horizontal direction is restricted.

[0029] A cooling unit 47 and a heater unit 49 are disposed in the back of the guide rail 5 in close proximity to each other from the front side. The heater unit 49 on the back side sandwiches the guide rail 5 and a pair of upper and lower heater bars 5 on the left side.
1, and a pair of upper and lower heater bars 51 is also provided on the right side. That is, in the heater unit 49,
A total of four heater bars 51 are provided.

The heater bar 51 is adapted to be moved up and down by a vertical actuator (not shown). The heater bar 51 includes a base bar 51a fixed to the lifting actuator, and a heat insulating material 51b and a heater 51 that are sequentially laminated on the opposing surface of the counterpart heater bar 51.
c, contact surface material (Teflon tape with glass cloth, etc.) 5
1d. The heater bar 51 is a so-called constant heater, and the contact surface member 51d is always maintained at a constant temperature.

The heater unit 49 moves the slide table 11 and raises and lowers the upper and lower heater bars 51 in the approaching direction.
The upper and lower contact surface members 51d are pressed against each other via the elongated hole 27 formed in the first contact hole 51a.

On the front side of the heater unit 49, the above-mentioned cooling unit 47 is provided. Cooling unit 4
Similarly to the heater unit 49, a pair of upper and lower cooling bars 53 are provided on the left side of the guide rail 5 and a pair of upper and lower cooling bars 53 are also provided on the right side. That is, the cooling unit 47 is provided with a total of four cooling bars 53.

As the cooling bar 53, for example, electronic cooling by a Peltier element can be used. Similarly to the heater bar 51, the cooling bar 53 is configured such that the upper and lower contact surfaces 53a are pressed against each other via the elongated hole 27 of the slide table 11.

A control unit 55 shown in FIG. 1 for automatically and sequentially controlling the movement of the slide table 11, the clamping operation of the clamper 21, the elevating and lowering of the heater bar 51 and the cooling bar 53, etc. An adjusting unit 57 that can adjust the transport speed, the elevating speed, and the temperature of these operation units is provided. A switch 59 for starting or stopping these operations is provided on the front surface of the device frame 13.

Next, a heat sealing method using the heat sealing device 11 configured as described above will be described. In order to perform heat sealing, first, the work 43 is placed on the buffer plate 39 of the handling jig 31, the lid 37 is closed, and the work 43 is fixed. As a result, the joining portion of the work 43 projects from both sides of the handling jig 31 in an ear shape.

The handling jig 31 is placed on the slide table 11 by inserting a fixing hole into the fixing pin 35 while holding the work 43 in this manner. When the work start switch of the heat sealing device 11 is pressed, the clamper 21 of the side tension unit 13 is rotated, and the work 4 protruding from both sides of the handling jig 31.
3 are sandwiched and fixed by the first cushioning member 23 and the second cushioning member 25 of the side tension unit 13 from above and below.

Thereafter, by rotating the slide cam 17, the slide 15 for side tension is moved away from the slide table 11. Therefore,
A tension is applied to the joint of the work 43 held by the handling jig 31. In this state, the slide table 11 is moved along the guide rail 5 to the heater unit 49 on the back side of the apparatus.

When the slide table 11 arrives at the heater unit 49, the left and right heater bars 51 are raised and lowered in a direction approaching from the vertical direction, and the joint of the work 43 disposed in the elongated hole 27 is moved up and down by the heater bar 51. Heating (at 180 ° C. or less) is carried out for a fixed time with a constant force (at least 0.196 Mpa or more) from the direction. Thereby, the resin layer provided inside the heated portion is melted.

Then, immediately (at least within 2 seconds, preferably within 1.5 seconds), the right and left and up and down heater bars 5
Then, the slide table 11 is moved to the cooling unit 47 in front, and the cooling bar 53 holds the cooling table 53 with a constant force from a vertical direction for a fixed time. That is, the heated portion is rapidly cooled.

After the cooling bar 53 has completed cooling and holding for a predetermined time, the left, right, upper and lower cooling bars 53 are separated from each other, and the slide table 11 is moved to the front of the apparatus frame 13. Next, the clamping of the work 43 by the clamper 21 is released, and the handling jig 31 is removed from the slide table 11. Next, the fixing of the lid 37 of the handling jig 31 is released, and the heat-sealed work 43 is taken out.

Next, the outside of the seal portion of the work 43 is removed by trimming, and as shown in FIG. 5, a completed pack material 57 in which both sides sandwiching the top seal portion 43a are joined by the side seal portions 43b is obtained. become.

In the above description, the side seal portion 4
Although the case where only 3b is joined is described, by changing the shape of the handling jig or the slide unit,
The top seal portion 43a can be similarly joined. In FIG. 5, reference numeral 59 denotes a tab of the pack material 57.

In the heat sealing method using the heat sealing device 11, the heated portion of the work 43 is clamped while being heated by the heater bar 51 for a certain period of time, and immediately after the heating and clamping, the heated portion is fixed by the cooling bar 53. It is clamped while being cooled for a time. As a result, wrinkling of the seal portion due to uneven shrinkage, which has conventionally occurred when cooling is performed naturally without pressurization, is suppressed by pressurization. Further, at this time, the re-solidified resin is easily cooled uniformly by being forcibly cooled at the same time, which also suppresses the generation of wrinkles. As a result,
There is no wrinkles on the contact surfaces, and the joint surfaces are tightly contacted with a uniform contact surface, thereby increasing the strength of the seal portion.

[0044]

EXAMPLE Next, the strength of a heat-sealed pack material using a heat-sealing device corresponding to the above-described heat-sealing device 11 was compared with that of a heat-sealed pack material by a conventional method. explain.

FIG. 6 is a graph comparing the transition of the heat sealing time and the temperature of the sealing portion between the conventional example and the present invention. FIG. 7 is a graph showing the sealing strength of the conventional (impulse heating) method.
FIG. 8 is a graph showing the seal strength of the conventional (constant heat) method, and FIG. 9 is a graph showing the seal strength of the present invention (cooling immediately after constant).

[Comparative conditions] In both the present invention and the conventional example, the width of the heat seal portion was 7 mm. The pressing force by the heater bar according to the present invention was 0.196 Mpa. The pressing force of the cooling bar according to the present invention was equal to or higher than the pressing force of the heater bar. As shown in FIG. 6, in the case of the heat sealing method and the constant heating method according to the present invention, heating was performed for 5 seconds. The heat sealing method according to the present invention comprises:
After heating for 2 seconds, rapid cooling was performed within 2 seconds. In the constant heating method, natural heating was performed after heating for 5 seconds. In addition, the impulse method, after heating for 2 seconds,
Natural cooling was performed.

As a result of measuring the sheet peeling strength of the seal portion obtained by these heat sealing methods, the heat sealing method of the present invention including the cooling and clamping step immediately after the heating and clamping step is the same as the conventional constant heating method, Compared to the impulse method, the peeling strength was found to be the largest value of 41.2 N / cm on average, as shown in FIG. Also, the standard deviation (StdDev) was reduced to 4.1 as compared with the constant heating method, and it was found that the variation in strength was reduced. In addition, it was found that Cpk was 1.7 in the heat sealing method according to the present invention, and high production control was possible. Furthermore, according to the heat sealing method of the present invention, it was found that the defect rate (DPM) was extremely low at 0.1. Note that the graphs in FIGS. 7 to 9 are defined as 20N or more only for the lower limit management standard (LSL) regardless of the upper limit management standard (USL) for the strength test.

[0048]

As described in detail above, in the heat sealing method according to the present invention, the heated portion is clamped while being heated by the heater bar for a certain period of time, and immediately after the heating and clamping, the heated portion is cooled by the cooling bar. Since the holding is performed while cooling for a certain period of time, wrinkling of the seal portion caused by shrinkage of a heated portion is not caused by pressurization in the cooling and holding step when cooling is conventionally performed without natural pressure. Also,
At this time, the resolidified resin after melting can be uniformly cooled by forced cooling. Therefore, the joining surfaces can be closely contacted with a uniform contact surface without wrinkles, and as a result, the strength of the seal portion can be increased. Further, forcible cooling can reduce the manufacturing time, and can improve the manufacturing efficiency.

The heat sealing device according to the present invention
Since a pair of heater bars for holding the heating portion for a certain period of time and a pair of cooling bars for holding the heating portion for a certain period of time after the completion of the heating and holding process were provided, the resin layer was melted. The heated portion immediately after can be rapidly cooled while applying pressure. This makes it possible to forcibly suppress wrinkles caused by shrinkage after melting, which has conventionally been caused by leaving the melting part to cool naturally. As a result, it is possible to achieve close contact with a uniform contact surface without wrinkles, and it is possible to achieve high-strength and short-time sealing between the joint surfaces of the sheets.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a heat sealing device according to the present invention.

FIG. 2 is an enlarged perspective view of a main part of the heat sealing device shown in FIG.

FIG. 3 is a perspective view showing a handling jig and a pack material set in the slide unit shown in FIG. 2;

FIG. 4 is an enlarged sectional view of an end portion of a pack material to which tension is applied by a side tension unit.

FIG. 5 is a plan view of a heat-sealed pack material.

FIG. 6 is a graph comparing the transition of the heat sealing time and the temperature of the sealing portion between the conventional example and the present invention.

FIG. 7 is a graph showing the seal strength of a conventional (impulse heating) method.

FIG. 8 is a graph showing the seal strength of a conventional (constant heat) method.

FIG. 9 is a graph showing the seal strength of the method of the present invention (cooling immediately after constant).

FIG. 10 is an explanatory diagram showing a procedure of a conventional heat sealing method using a constant heater.

[Explanation of symbols]

11: heat sealing device, 43: sheet (work), 5
1: Heater bar, 53: Cooling bar

Claims (7)

[Claims] 1. A method of melting a resin layer at a heated portion by aligning the bonding surfaces of a pair of sheets provided with a resin layer on a bonding surface and holding the back surfaces of the pair of sheets while heating the pair of sheets. A heat sealing method for tightly sealing between the joining surfaces of the sheets, wherein the heating section is held while being heated by a heater bar for a predetermined time; and immediately after the heating holding step, the heating section is cooled with a cooling bar. And a step of sandwiching while cooling for a certain period of time. 2. The heat sealing method according to claim 1, wherein the pressing force of the cooling bar for holding is larger than the pressing force of the heater bar for holding. 3. The heat sealing method according to claim 1, wherein the heating and cooling sandwiching is performed while applying tension to a region of the sheet including the heating portion. 4. The heat sealing method according to claim 1, wherein the switching time from the end of the heating nip process to the start of the cooling nip process is 2 seconds or less, more preferably 1.5 seconds or less. 5. The width of a sealing portion which is tightly sealed along the heater bar and the cooling bar is 3 mm or more and 10 mm or more.
The heat sealing method according to claim 1, wherein the thickness is not more than mm. 6. The heat sealing method according to claim 1, wherein a pressing force for holding the heater bar is at least 0.196 Mpa. 7. A resin sheet at a heated portion is melted by aligning the joining surfaces of a pair of sheets provided with a resin layer on the joining surface and holding the back surfaces of the pair of sheets while heating the back surfaces of the pair of sheets. And a pair of heater bars for holding the heated portion while heating the heating portion for a certain period of time in a heat sealing apparatus for tightly sealing between the joining surfaces of the sheets. A heat sealing apparatus comprising: a pair of cooling bars that sandwich a portion while cooling a portion for a predetermined time.