JP3522569B2 - Heat seal roll - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging film, most of which is a heat-sealing roll for heat-sealing a laminated packaging film having a heat-sealing resin layer.
Regarding a heat seal roll suitable for use as a horizontal seal roll of an automatic filling bag making machine, a packaging film is run at a speed exceeding 20 m / min and still achieves proper heat seal.

[0002]

2. Description of the Related Art As a conventional heat-sealing roll of this kind applied to an automatic filling and bag-making machine, the applicant previously proposed JP-A-5-278113 and JP-A-5-329.
There is one disclosed in Japanese Patent No. 932.

The former heat-sealing roll is characterized in that a transverse heat-sealing blade is provided with a portion having a lower thermal conductivity than the heat-sealing blade itself inside the central portion in the circumferential direction. When heat-sealing a packaging bag, this makes the surface temperature of the front and rear ends of the horizontal heat-sealing blade in the rotational direction as high as necessary, while suppressing the surface temperature of the central portion in the circumferential direction to be low. The thermal fusion resin layer is prevented from overmelting in the film portion in contact with the surface of the central portion in the circumferential direction, and the packaged product is prevented from remaining on the lateral heat seal portion.

In the latter heat seal roll, a dissimilar material having a higher thermal conductivity than the heat seal blade itself is mounted on the side surface of the horizontal heat seal blade on the front side in the rotation direction, and the heat seal blade is mounted in the circumferential direction. Inside the central part, a part with lower thermal conductivity than the heat seal blade itself is provided,
The surface of the heat seal blade provided on at least one of the rolls has the same radius of curvature for both the front side portion and the rear side portion in the rotation direction, and the radius of curvature of the circumferential center portion of the surface of the heat seal blade. It is characterized by being made smaller.

According to this heat-sealing roll, the temperature of the front side portion in the rotation direction of the heat-sealing blade is sufficiently increased by the action of the dissimilar material having a high thermal conductivity attached to the heat-sealing blade, so that the speed is high. As soon as the heat-sealing blade comes into contact with the packaging film running at speed,
The hot-melt resin layer of the packaging film can be sufficiently melted to always provide proper heat-sealing, and the heat-sealing blade is provided inside the central portion in the circumferential direction. By effectively suppressing the temperature rise on the surface of the central part and preventing over-melting of the hot-melt resin layer by the action, avoiding the residue of the packaged product on the heat-sealing part, further improving the heat-sealing strength. You can

Further, in this heat-sealing roll, the radius of curvature of the front side portion and the rear side portion of the heat-sealing blade in the rotation direction and the radius of curvature of the central portion in the circumferential direction of the heat-sealing blade are different according to need. By attaching
Regardless of the thickness of the heat-melting resin layer of the packaging film itself, the total thickness of the heat-melting resin layer at the heat-sealing part adjacent to the packaging space should be sufficiently thick to achieve the desired heat-sealing strength. Can be brought about, and therefore, the material yield of the hot-melt resin layer is sufficiently improved,
In addition, the problem of overpacking can be effectively eliminated.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a further improvement of the conventional heat-sealing roll. When performing transverse heat-sealing by the heat-sealing roll, the heat-sealing blade is centered in the circumferential direction. Even if impurities such as a liquid containing water and a solid containing water that are the objects to be packaged remain between the two packaging films sandwiched by the parts, the inclusion of the impurities is particularly important. By sufficiently preventing volume expansion due to evaporation of water,
It is possible to realize excellent horizontal heat sealing at all times. Moreover, by continuously packaging the objects to be packaged by the automatic filling bag-making machine, the continuous heat sealing of continuous strip-shaped packaging bags that are continuously manufactured in a strip shape can be performed. A heat-sealing roll that can sufficiently remove the risk of residual contaminants dripping from the cutting point, oozing out, spilling, etc., when cutting and separating into single bags or required multiple bags at approximately the center position. Is provided.

[0008]

The heat-sealing roll of the present invention is applied to, for example, an automatic filling bag-making machine, is arranged in close proximity to each other, and is paired with two rolls which are rotationally driven in opposite directions. An egg roll, a heater built in the roll, a heat seal blade provided on the roll, protruding outward in the radial direction thereof, extending in the axial direction, and having a surface arcuate in the circumferential direction. Yes, the cross-sectional shape of the heat-sealing blade is almost gate-shaped, and the mutual connection part between the two columnar parts and the beam-shaped part that spans them is particularly thin, and the thickness of the beam-shaped part is Is thicker than the connecting portion to the columnar portion at least in the central region in the length direction.

In this heat-sealing roll, the heat-sealing blade having a gate-shaped cross section has a required wall thickness at each of the columnar portions on the front side and the rear side in the rotating direction, so that the heat of the heater can be reduced. Based on the heat conduction through the columnar part of the heat seal blade, the surface temperature of each of the front side and the rear side in the rotation direction of the heat sealing blade is set to the intended temperature for proper heat sealing of the packaging film. be able to.

Further, here, the connecting portion between the columnar portion and the beam-shaped portion is made thin, and the heat conduction from each of the columnar portions to the beam-shaped portion is suppressed to limit the amount of heat transferred, whereby the heat seal blade The surface temperature of the central portion in the circumferential direction can be advantageously reduced as compared with that on the front side and the rear side in the rotational direction.

Therefore, immediately after the packaging film is sandwiched between the pair of heat-sealing blades, the heat-sealing resin layer of the packaging film at the front side in the rotating direction of the heat-sealing blade is transferred to the film running speed, and thus to the heat. The rotation speed of the seal roll is fast, yet it can be melted to the required depth, and the packaging film is always properly and heat-sealed with high fusion strength from the contact start end with the heat-sealing blade. Become.

This is almost the same for the rear side portion of the heat-sealing blade in the rotational direction, and based on the surface temperature properly heated under the action of the columnar portion, immediately after sandwiching the packaging film, it is sufficiently Heat seal can be applied.

On the other hand, the central portion in the circumferential direction of the heat-sealing blade is only heated to a relatively low temperature by the small amount of conduction heat from each columnar portion, and the cross-sectional shape is beam-like. The circumferential center portion, by sandwiching the packaging film between the pair of heat-sealing blades, tends to be bent and deformed in a direction away from the film, so by the circumferential center portion of the heat-sealing blade,
The heat-sealing resin layer of the sandwiched film portion is not heated to such a high temperature, but is slightly melted and incompletely bonded. Therefore, for example, in the automatic filling bag-making machine, when performing the foreign matter sealing sandwiching the object to be packaged between the packaging film, even if the foreign matter may remain in the circumferential center portion of the heat seal blade, The impurities themselves are not heated to a temperature high enough to evaporate the moisture contained therein, and therefore the moisture contained in the impurities evaporates, resulting in a significant increase in the occupied volume. There is no risk of problems such as interference with the fusion of the resin layer and peeling of the fusion surface.

In performing such foreign matter sealing, the foreign matter sandwiched between the front side and the rear side in the rotation direction of the heat-sealing blade has a proper melting state of the heat-sealing resin layer. Below, before the water content of the impurities becomes water vapor, along with a part of the heat-sealing resin, many will be pushed to the rear side in the rotation direction of the heat seal roll, so the rotation direction of the heat seal blade Contaminants do not remain in the proper heat-sealed portion formed by the front side portion and the rear side portion.

In addition, in this heat-sealing roll, the central region in the lengthwise direction of the beam-shaped portion of the heat-sealing blade, that is, the central region of the circumferential-direction central portion of the heat-sealing blade is defined as the columnar portion of the beam-shaped portion. By increasing the heat capacity and rigidity of the beam-shaped part by making it thicker than the connecting part to, the heat seal blade finishes one work and starts the next work based on the rotation of the heat seal roll. In addition to ensuring the temperature recovery of the central part in the circumferential direction up to the set temperature, the amount of heat supplied to the packaging film is controlled by the thick part in the central region to In addition, flexural deformation of the central portion in the circumferential direction in the direction away from the sandwiching film is advantageously reduced.

Therefore, in this heat-sealing blade, the packaging film is also sufficiently strongly clamped by the thick portion in the central portion in the circumferential direction, and the heat-sealing resin layer thereof is melted to a required depth, It can be heat-sealed firmly without any impurities remaining. That is, the heat-fusible resin layer is appropriately melted even by this thick portion, so that it is possible to ensure sufficient removal of impurities and to realize high fusion strength.

Thus, the strip-shaped continuous packaging bag manufactured by the automatic filling bag-making machine is heat-sealed by the thick portion, and at the center position in the width direction of the horizontal heat-sealing portion, the required number of packaging bags are collected. By cutting and separating, even if contaminants remain between the proper heat-sealing parts due to the front side and the rear side of the heat-sealing blade in the rotation direction, dripping, oozing, spilling, etc. of the contaminants The fear can be sufficiently removed.

The same applies to the case where the beam-shaped portion of the heat-sealing blade is thicker than the connecting portion in all or most of the portion except the connecting portion. The thickest part is the thickest part, generally proper heat sealing of the heat-sealing resin layer is performed in the central region in the length direction, and in other regions of the central part in the circumferential direction of the sheet sealing blade, The heat-sealing resin layer is heated to such an extent that the water content of the contaminants does not evaporate, and thus is incompletely fused.

Further, in another heat seal roll of the present invention, in particular, the beam-shaped portion is thicker than the connecting portion to the columnar portion at least in the central region in the longitudinal direction thereof, instead of the beam-shaped portion. A pillar is provided so as to project in the columnar portion and the circumferential direction from a substantially central portion in the longitudinal direction of the portion.

According to this, it is possible to impart high rigidity to the circumferential center portion of the heat seal blade under the action of the support pillar, and also conduct the heater heat to the surface of the heat seal blade via the support pillar. It is also possible to prevent flexural deformation of the central portion in the circumferential direction in the direction away from the sandwiching film, and also to improve heat recovery from one work to the next in the central portion in the circumferential direction. It is possible to make sure that the heat-sealing resin layer is properly heat-sealed by the portion corresponding to the protruding position of the support.

[0021] Here, the heat transmitted through the support column overheats the entire central portion in the circumferential direction of the heat-sealing blade, in other words, the thin connecting portion loses its significance of existence, and the central portion in the circumferential direction of the heat-sealing blade is lost. In order to sufficiently prevent the water content of impurities that may remain in the portion corresponding to the portion from evaporating, it is preferable that the wall thickness of the column is considerably smaller than the wall thickness of each columnar member. .

In the heat-sealing roll as described above, preferably, the columnar portion of the heat-sealing blade located on the front side in the rotation direction of the roll is thicker than the columnar portion located on the rear side. According to this, since the front side portion in the rotation direction of the heat seal blade is heated to a particularly high temperature, the traveling speed of the packaging film becomes high, and the contact time between the heat seal blade and the packaging film is short. Even so, the front side portion in the rotation direction of the heat seal blade can supply a sufficient amount of heat from the beginning of contact with the packaging film to bring about a more proper heat seal of the heat fusion resin layer. .

On the other hand, the rear portion in the rotational direction of the heat seal blade is heated to a temperature lower than the front portion in the rotational direction and higher than the central portion in the circumferential direction by the action of the thin side columnar portion, The amount of heat supplied from the rear side portion to the heat fusion resin layer of the packaging film is smaller than that supplied from the front side portion of the heat sealing blade to the heat fusion resin layer. However, the heat-sealing resin layer sandwiched by the rear side portion of the heat-sealing blade receives heat from not only the rear side portion but also the already-melted portion of the heat-sealing resin layer. A part of the above is absorbed by the foreign matter inscribed in the hot-melt resin layer, and is made into an appropriate molten state with the balance of the supplied heat amount, so that excellent heat sealing with no foreign matter remaining can be realized.

Further, preferably, the space defined by the columnar portion and the beam-like portion of the heat-sealing blade is set to a negative pressure, more preferably a vacuum. In this case, the air in the space is sufficiently reduced, and the heat transfer to the beam-shaped portion due to the convection of air in the space, in other words, the central portion in the circumferential direction of the heat seal blade is effective. Therefore, it is easy to control the surface temperature difference between each columnar portion and the beam-shaped portion.

By the way, in order to form such a negative pressure space, the base end of each columnar portion of the heat seal blade,
If it has struts, it is preferable to also hermetically connect the base ends of the struts to the base frame to make the entire heat seal blade a central structure, which allows it to be independent of the roll itself. A negative pressure space can be created, making it easier and more reliable to achieve and maintain a negative pressure condition.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a transverse cross-sectional view showing an embodiment of the present invention. In the figure, 1 is a pair of rolls which are arranged in close proximity to each other and are driven to rotate in opposite directions. A heater as a heating source built in the roll 1 is shown. Here, each roll 1
A heat-sealing blade 3 which projects radially outward, extends in the axial direction thereof, and has an arcuate surface in the circumferential direction.
Is provided integrally with or separately from the roll 1, or separately as shown in the drawing. Further, as shown in the figure, each of the three heat-sealing blades 3 provided at equal intervals in the circumferential direction on one roll 1 is based on the synchronized rotational movement of the two rolls 1. In cooperation with another heat sealing blade 3 facing each other at an appropriate interval, a packaging film 4 which has been previously longitudinally sealed and filled with an object to be packaged is provided with a top seal and a bottom seal of a packaging bag. It is possible to apply a horizontal seal that also serves as the above, and thereby, the packaging film 4 is made into a continuous packaging bag in a band shape.

Further, here, the cross-sectional shape of the heat-sealing blade 3 is substantially gate-shaped, and the mutual connecting portions 8 of the two columnar portions 5 and 6 and the beam-shaped portion 7 extending over them are illustrated. As is apparent from the enlarged view of FIG. 2, the beam is made particularly thin, and the thickness of the beam-like portion itself is made thicker than that of the connecting portion 8 at least in the central region in the longitudinal direction.

According to FIG. 2, by making the outer surface of the beam-shaped portion 7 into an arc shape and the inner surface thereof into an arc-shaped straight line shape, the inner surface of the beam-shaped portion 7 can be connected to the respective columnar portions 5 and 6. The contact position, that is, the thickness of the connecting portion 8 is reduced, and the thickness of the connecting portion 8 is gradually increased toward the central portion in the length direction of the connecting portion 8. Is thinned, for example, as shown in FIG.
Can also be realized by providing a notch 9 along the columnar portions 5 and 6, and the thickening of the central region of the beam-shaped portion can be achieved on the inner surface of the central region as shown in FIG. As shown in (c), it can also be realized by providing a projecting portion 10 that projects smoothly or stepwise toward the lower side of the figure.

In such a heat-sealing blade 3, more preferably, the thickness D of the columnar portion 5 located on the front side in the rotation direction of the roll 1 is the thickness D of the columnar portion 6 located on the rear side.
It is made thicker than 1, and more preferably, the space 11 defined by the columnar portions 5 and 6 and the beam-shaped portion 7 is set to a negative pressure, preferably a vacuum. In this case, when the heat-sealing blade 3 is composed of the columnar portions 5, 6 and the beam-shaped portion 7 and both end walls in the length direction, it is necessary to hermetically close the space 11 with the roll 1. .

By the way, when the roll itself is to contribute to hermetically seal the space 11, the heat seal blade 3 is detached,
Each time the heat-sealing blade 3 is loosened due to a position change or the like, there is a disadvantage that the space returns to the atmospheric pressure. Therefore, as shown in FIGS. The base end is airtightly connected to the base frame 12 and the space 11 is preliminarily evacuated when the heat-sealing blade 3 is manufactured, so that the inconvenience can be sufficiently prevented.

FIG. 4 is an enlarged cross-sectional view showing another embodiment of the present invention. The heat-sealing blade 3 has a beam-shaped portion 7
Instead of thickening at least the central region in the length direction, the columnar parts 5, 6 are formed from the inner surface of the central part in the length direction.
And a column 13 protruding in the circumferential direction.

Also in this heat-sealing blade, in order to make the internal space 11 negative pressure or vacuum, the columnar parts 5, 6
To airtightly connect the to the base frame 12
It is preferable to connect the base frame 12 to the base frame 12 in order to advantageously restrain the flexural deformation of the beam-shaped portion 7, and also to increase the heat transfer coefficient from the roll 1 to the column 13 and, in addition, to the column 13
In order to eliminate the possibility that the vacuum on both sides of the column is broken at the same time, it is preferable that the column 13 is also hermetically connected to the base frame 12. When the packaging film 4 is laterally sealed with the heat-sealing roll 14 provided with the heat-sealing blade 3 having the above-described structure, the heat-sealing blade 3 is used.
Each of the front side portion and the rear side portion in the rotation direction of
Under the action of each of the columnar portions 5 and 6, a sufficient amount of heat is supplied from the heater 2 built in the roll 1 to appropriately melt the heat-sealing resin layer of the packaging film 4, and to leave impurities. Appropriate heat sealing is applied.

On the other hand, at the central portion in the circumferential direction of the heat-sealing blade 3, since the connecting portion 8 between the columnar portions 5, 6 and the beam-shaped portion 7 is particularly thin, these columnar portions 5, 6 are formed.
Therefore, only a small amount of heat is supplied under a low thermal conductivity, so that the heat fusion resin layer of the packaging film 4 sandwiched in the central portion in the circumferential direction has impurities remaining between them. Even in such a case, it is not heated to such a high temperature that the water content of the contaminants evaporates, so that the particles are incompletely fused in a slight molten state.

By the way, in such a circumferential central portion, when a thick portion is provided in the central region of the beam-shaped portion 7,
At the portion corresponding to the thick portion, the amount of heat transferred to the heat-sealing resin layer of the sandwiching film is large, and moreover, the packaging film 4 is sandwiched sufficiently strongly, so that no foreign matter remains here either. Strong heat sealing will be performed. Therefore, when separating a continuous packaging bag in strips into the required number of bags, cutting it at the heat-sealing portion by the thick portion may cause dripping of residual impurities, bleeding, etc. Can be sufficiently removed.

In addition to these, the pillar 13 is provided in the central portion of the beam-shaped portion 7, the heat of the heater 2 is conducted to the central portion of the beam-shaped portion through the pillar 13, and the central portion and its vicinity are provided. It is almost the same when the flexural rigidity is increased,
The heat-sealing resin layer of the packaging film can be heat-sealed sufficiently strongly at the portion corresponding to the column 13 and the portion in the vicinity thereof.

By the way, such a function of the heat-sealing blade 3 is such that the front side columnar portion 5 is made thicker than the rear side columnar portion 6 so that the surface temperature of the front side columnar portion 5 becomes higher, Will be more effectively exerted when a large amount of heat can be supplied to the heat-sealing resin layer immediately after it comes into contact with the packaging film, and it is partitioned by the columnar parts 5, 6 and the beam-like part 7. Even when the space 11 to be heated is set to a negative pressure, preferably a vacuum, and excessive heating of the beam-shaped portion 7, in other words, the central portion in the circumferential direction of the heat-sealing blade 3 is prevented due to the convection of air in the space. It will also be more effectively demonstrated.

[0037]

EXAMPLES Example 1 Using a heat-sealing roll having the structure shown in FIG. 1, the heat-sealing blade sandwiches the packaging film with a pressure of 350 KPa on the vertical sealing side and 220 KPa on the film folding side, and 30 As shown in Fig. 5, the temperature of the heater heating where the horizontal heat sealing was performed adequately was measured in relation to the traveling speed of the packaging film. The temperature range was sandwiched by the broken lines in the graph shown. Here, in a temperature range exceeding the upper broken line, water as an impurity is evaporated in the horizontal seal portion, and sufficient heat seal strength cannot be obtained, and in a temperature range lower than the lower broken line, Due to insufficient melting of the heat-sealing resin layer, sufficient heat sealing strength could not be obtained. The comparative examples in the table are different from the above-mentioned examples only in that the heat-sealing blade has a solid structure. In this comparative example, the proper heater heating temperature range is a range surrounded by a solid line. became.

As shown in FIG. 5, the proper temperature range of the embodiment is much wider than that of the comparative example, and the traveling speed of the packaging film 4 is 10 to 20 in that range.
It is clear that there is virtually no change in the m / min range. As described above, in the embodiment, as a result of widening the proper temperature range of the heater temperature, the traveling speed of the packaging film is further increased, and the occurrence of the sealing failure is effectively performed without controlling the heater temperature so strictly. Can be prevented.

Example 2 The sandwiching pressure of the packaging film by the heat-sealing blade in the previous example was 527 KPa on the vertical sealing side and 377 K on the film folding side.
It is changed to Pa, and the comparative example is also different from the example only in that the heat seal blade has a solid structure. The proper heating area of the embodiment is shown in FIG.
The comparative example is shown sandwiched by solid lines. As shown in FIG. 6, it can be understood that the suitable temperature range in the example is wider than that in the comparative example, and this tendency becomes more remarkable as the traveling speed of the packaging film becomes faster. Therefore, also in this embodiment, similarly to the first embodiment, the traveling speed of the packaging film is increased, and the control of the heater temperature is not performed so strictly, and the occurrence of the sealing failure can be effectively prevented. You can

[0040]

As is apparent from the above description, according to the present invention, when sealing a packaged object with foreign matter, the foreign matter is sandwiched by the central portion in the circumferential direction of the heat seal blade. Even when remaining between the packaging films, it is possible to prevent evaporation of moisture contained in the residual impurities and always realize excellent lateral heat sealing. In addition, in separating the continuous packaging bag in a strip shape into the required number of bags, by cutting the continuous packaging bag in the central portion of the horizontal heat-sealing portion, residual impurities are dropped,
It is possible to sufficiently prevent dropping and the like. Moreover, as described in the examples, by increasing the proper temperature range of the heater with respect to the traveling speed of the packaging film, the traveling speed of the packaging film can be increased and the heater for proper heat sealing can still be obtained. The temperature can be easily controlled.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a heat seal blade.

FIG. 3 is a partial cross-sectional view showing another configuration of the heat seal blade.

FIG. 4 is an enlarged cross-sectional view showing another form of the heat seal blade.

FIG. 5 is a graph showing the measurement results of Example 1.

6 is a graph showing the measurement results of Example 2. FIG.

[Explanation of symbols]

1 roll 2 heater 3 heat seal blades 4 Packaging film 5,6 columnar part 7 Beam-shaped part 8 connection 9 notches 10 Projection 11 space 12 base frame 13 props 14 Heat seal roll

Continuation of the front page (56) Reference JP-A-5-329932 (JP, A) JP-A-5-278113 (JP, A) JP-A-5-237939 (JP, A) JP-A-61-25825 (JP , A) JP-A-10-316114 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65B 51/10 B65B 51/16

Claims (6)

(57) [Claims] 1. A roll which is rotationally driven, a heater which is built in the roll, and a roll which is provided on the roll, projects outward in the radial direction thereof, extends in the axial direction, and has an arc-shaped surface in the circumferential direction. A heat-sealing roll having a sealing blade, wherein the heat-sealing blade has a substantially cross-sectional shape in the form of a gate, and the two columnar portions and a beam-shaped portion straddling them are connected to each other. Especially thin, the thickness of the beam-like portion,
A heat-sealing roll having a thickness greater than that of the connecting portion to the columnar portion at least in the central region in the length direction. 2. A roll which is rotationally driven, a heater which is built in the roll, and a roll which is provided on the roll, projects outward in the radial direction thereof, extends in the axial direction, and has an arc-shaped surface in the circumferential direction. A heat-sealing roll having a sealing blade, wherein the heat-sealing blade has a substantially cross-sectional shape in the form of a gate, and the two columnar portions and a beam-shaped portion straddling them are connected to each other. In particular, a heat-sealing roll having a thin wall, in which a column is projected from a substantially central portion in the lengthwise direction of the beam-shaped portion and a column is circumferentially provided. 3. The heat-sealing roll according to claim 1, wherein the columnar portion of the heat-sealing blade located on the front side in the roll rotation direction is thicker than the columnar portion located on the rear side thereof. 4. The heat seal roll according to claim 1, wherein the space defined by the columnar portion and the beam portion of the heat seal blade is a negative pressure. 5. A heat-sealing blade, wherein each base end of each columnar portion is airtightly connected to a base frame.
4. The heat seal roll according to any one of 4 above. 6. The heat-sealing roll according to claim 2, wherein each columnar portion of the heat-sealing blade and the base end of the column are airtightly connected to the base frame.