JP2024040544A - A heat-sealing device that forms a composite heat-sealing structure in which a strip-shaped peelable seal is added in the longitudinal direction of the strip-shaped peelable seal. - Google Patents

Abstract

To provide a heat sealing device capable of surely sealing even if a heat-sealing material has rigidity similar to a cup or a tray.SOLUTION: In a heat sealing device that performs heat sealing by sandwiching and crimping a heat-sealing material between crimping bodies of which at least one is a heating body, a linear projection is provided on a heating surface of the heat-sealing material of the heating body, an elastic body is arranged on the heating surface of the heat-sealing material on both sides of the leaner projection, and a composite heat sealing structure to which a linear peelable seal is added in a longitudinal direction of a strip-shaped peelable seal is formed.SELECTED DRAWING: Figure 4

Description

The present invention relates to a heat-sealing device that forms a composite heat-sealing structure in which a linear peel-off seal is added in the longitudinal direction of a strip-shaped peel-off seal.

Flexible packaging bags made of plastic film or sheet are sealed using heat sealing, which utilizes the thermoplasticity of plastic. The strength of this thermal bond increases as the temperature of the bonding surface increases, the bonding layer softens and becomes an interfacial bond (peelable seal) between the bonding surfaces, and when it reaches a molten state, the bonding layer (sealant layer) becomes paste-like. When cooled, the adhesive surface becomes a cohesive adhesive (broken seal) in a molded state (integrated). The adhesive strength in the above-mentioned interface adhesion is determined by the welding surface temperature (heating temperature) and heating speed (Hishinuma effect).

As described above, there are two types of heat seals: peelable stickers whose adhesive surface can be peeled off, and tearable stickers that cannot be peeled off, but there are growing expectations for the application of peelable stickers because of the convenience of opening.

There are several types of bags formed by heat sealing, but among them, in the case of gusset bags, the film forming the bag is The number of sheets has increased, and the boundaries between them have become stepped. The gusset bag has gusset folds on both sides, and a center seal with a gassho attached in the vertical direction. These parts have four parts, and there are two parts between them, so the boundary between them is a stepped part. The inventor discovered that when a bag with such a step is heat-sealed with a peel-off seal, leakage occurs at the step. The problem was solved by developing a new heat seal structure that adds a seal (Patent Document 1).

A typical heat sealing method is an intermittent heating method using heat jaws. In this method, a heat sealing material is placed between a pair of heating bodies, and heat sealing is performed by moving one or both of the heating bodies back and forth. In the device used for this, a heater is embedded inside each of the opposing heating bodies, and a heat pipe is further embedded in the vicinity of the heat sealing surface. Each of the heating bodies is equipped with a temperature control sensor near the heater, and a sensor for measuring the surface temperature of the heating body on the heat sealing surface. The heat-sealed surface is covered with a cover material. A heat sealing material (work) is placed on one heating element, and the other heating element is lowered to press the heat sealing material to perform heat sealing.

After heat sealing is completed, the heating element is raised to take out the heat sealing material, and this intermittent operation is repeated. In the method of adding a filamentous seal, a filamentous protrusion is provided on the heat sealing surface of the heating element, and a heat-resistant elastic body with a thickness of 3 to 5 mm is provided on the surface of the other heating element. In this case, no cover material is attached.

A schematic diagram of this device is shown in FIG. In the figure, the heating bodies are arranged one above the other, a linear protrusion is provided on the heating surface of the upper heating body, and an elastic body is mounted on the heating surface of the lower heating body. A heat-sealed pillow bag is placed between the heating elements. When the upper heating element descends and presses against the pillow bag, the crimp portion is heat-sealed over its entire length, and at this time, the filamentous protrusions are pushed into the elastic body.

Patent No. 5779291

In the heat-sealing device for filamentous protrusions that was previously developed by the present inventor, the filamentous protrusions are pushed into an elastic body to form a filamentous seal. This resulted in a problem of insufficient strength.

The rigidity (Young's modulus) of ordinary plastic materials is several tens of MPa. However, the stretched film that is popular in the market and has transparency that makes it easy to see the contents and appropriate stiffness has a very high stiffness due to the orientation of the crystals, reaching 3,000 to 4,000 MPa at room temperature. It has become.
Table 1 shows catalog data on the Young's modulus of typical plastic materials used in today's packaging.

In particular, in the case of cups and trays where one side is rigid, it is not easy to form a filamentous seal.

In order to solve the above problem, the inventor of the present invention conducted extensive research and came up with the idea of separating the seal by the linear protrusion from the seal by surface pressure bonding, thereby making it possible to reliably perform the respective crimping operations. Sealing using linear protrusions can be achieved by adhering the linear protrusions through the heat-sealing material and pressing them against the opposing heating element without using an elastic body. I thought that it might be possible to form a In this case, the crimp stress on the flat portion would be insufficient due to the striated protrusions, so we considered increasing the crimp stress on the flat portion by arranging elastic bodies on both sides of the striated protrusions.

Therefore, in order to confirm this, an apparatus shown in FIG. 1 was manufactured. This device consists of upper and lower heat bars that are heating bodies, and is a device that lowers these heat bars to press and heat-seal the heat-sealing material. Two types of heat bars (lower 2) were prepared: and a heat bar without striated protrusions. The linear projection has a trapezoidal cross section with a tip width of 0.3 mm and a bottom width of 0.5 mm, and a height of 0.5 mm. A 3 mm thick silicone rubber plate made of Shore A50 was installed as an elastic body on the heat bar (lower 2) without linear protrusions.

FIG. 2 shows the results of measuring the relationship between the compression margin and the crimp pressure of silicone rubber plates for shore A50 and A70 with thicknesses of 3 mm and 5 mm. Based on this result, a rubber plate having Shore A50 and a thickness of 3 mm, which has the desired characteristics in terms of compression allowance and generated stress, was used.

As the heat-sealing material, a two-layer film of OPP 30 μm/LLDPE 25 μm, which is the most popular on the market, was used. The surface material OPP has a melting point of 165°C and a Vicat softening temperature of 80 to 100°C, and the sealant LLDPE has a melting point of 111 to 124°C and a Vicat softening temperature of 41 to 85°C. Two types of test specimens were used: one with two sheets folded in the middle (work (1)) and one with a center seal (Lf) of 10 mm width to make a pillow bag (work (2)). The crimping area was set to have a length (L) of 45 mm or 90 mm and a width (W) of 16 mm.

The crimping time was approximately 5 seconds to reach 99% of the contact surface temperature of the heat bar, and the crimping load was 48N and 100N so that the crimping pressure applied to the specimen was around 0.1 MPa, which is the lowest recommended crimping pressure. Selected.

Table 2 shows the crimping stress generated by the crimping area and the crimping load.

The heating surface temperature was changed from 90 to 128°C to perform heat sealing, and deep scratch liquid (equivalent to JIS Z 2343-2) was dripped onto the resulting heat-sealed edge, and the passage of the liquid was observed with a magnifying glass.

Table 3 shows the heat sealing results for the two-ply test specimen. In the same table, "with one stripe" which is a striated protrusion is the result obtained using the heat bar (lower 1), and "flat" which is a flat part and "corner" which is a bent part is a result obtained using a heat bar (lower 1). These are the results obtained using 2).

As can be seen from Table 3, in local crimping using linear protrusions (with one strip), under both 48N and 100N loads, sealing begins at 94°C, where the LLDPE of the sealant begins to soften, including the bending corners. has been completed.

On the other hand, the sealing of the flat part started at 110° C., when the OPP of the surface layer material softened. This is because the sealing of plastic materials is a physical phenomenon that is achieved not by adhesive strength but by the airtightness of the adhesive surface (Collection of Abstracts of the 25th Annual Conference of the Japan Society of Packaging 2016).

Sealing the corner, which is a bent part, requires heating to 114-116°C, which is higher than the 113°C where the OPP surface material softens more, and as the pressure increases to 0.15 MPa, the temperature decreases to around 113°C. are doing.

As a result, even when the linear protrusions are directly pressed against the opposing heat bar, which is a metal plate, through the heat-sealing material, the heat-sealing material, which is only 110 μm thick when stacking two sheets, does not break, and the formed linear seal part It was confirmed that there was no problem with the breaking strength.

Table 4 shows the heat-sealing results for test specimens of pillow bags having center seals with four layers in addition to two layers. In this experiment, the silicone rubber plates used for the heat bar (lower 2) were placed on both sides of the linear projections of the heat bar (lower 1).

As shown in Table 4, all four parts were completely sealed at 94°C, when the LLDPE began to soften. This is because the entire load is applied from the start of plane crimping of the 4-sheet portion until the crimping of the 2-sheet portion is reached, resulting in a high crimping pressure (≈0.2 to 0.6 MPa).

In order to eliminate the through-holes in the stepped portion between the 4-piece and 2-piece parts, crimping using the linear protrusions completes the sealing at 112-113°C, when the OPP of the surface layer material begins to soften.

Since the crimping of the 2-sheet portion and the 4-sheet portion begins after the depression of the 2-sheet portion, the crimping of the 2-sheet portion becomes insufficient. The deficiency is compensated for by the softening temperature, so the sealing completion is shifted to 114-116°C.

From the above results, if heat sealing is performed with elastic bodies placed on both sides of the filamentous protrusions, the flat part can be crimped with good pressure even if there is a step, and the filament seal can also be formed well. Therefore, we have found that a good composite heat-sealed structure can be formed even if the heat-sealed material remains rigid.

That is, the present invention provides a heat sealing device that performs heat sealing by sandwiching and pressing a heat sealing material between compression bodies, at least one of which is a heating body, in which linear protrusions are formed on the heating surface of the heat sealing material of the heating body. A strip-shaped peel-off seal is added in the longitudinal direction of the strip-shaped peel-off seal, characterized in that an elastic body is arranged on the heating surface of the heat-sealing material on both sides of the filament protrusion. A heat sealing device that forms a composite heat sealing structure is provided.

According to the present invention, a heat seal with a composite heat seal structure including a filament seal can be formed with a peel-off seal regardless of the rigidity of the heat seal material, and a highly airtight seal can be obtained even for a cup or tray. .

Schematic diagrams of the front and side views of the heat sealing device used to confirm the configuration of the present invention Graph showing the relationship between compression allowance of silicone rubber plate and generated stress Schematic diagram of the front view of an example of the heat sealing device of the present invention and its cross section taken along line AA' Enlarged view of the heat bar (top) of the heat sealing device in Figure 3 A graph showing the relationship between compression allowance and generated stress when a pillow bag is heat-sealed using the heat-sealing device shown in Figure 3. Graph showing the relationship between adhesive surface temperature and heat seal strength when OPP/LLDPE laminated film is used as the heat seal material Schematic diagrams of the front side and the back side of the heat bar of an example in which the heat sealing device of the present invention is applied to sealing the lid of a cup. Graph showing the relationship between adhesive surface temperature and heat seal strength in that case Graph showing changes in bonding surface temperature and interface temperature over time for bonding in that case. Front and side schematic diagrams of a heat sealing device forming a conventional composite heat seal structure

The heat-sealing materials to be heat-sealed by the heat-sealing device of the present invention may have at least one thermoplastic resin and the other material that can be thermally bonded to the thermoplastic resin, but usually both are thermoplastic resins. Formed into packaging bags, packaging containers, etc. using films or sheets.

Packaging bags include four-sided seal bags that are made by stacking two sheets and sealing the four sides, three-sided seal bags that are made by folding sheets and sealing three sides, pillow bags that have gassho stickers on the center part of the bag, and pillow bags that have the center part sealed. There are stacked envelope bags and gusset bags with gussets on both sides of the pillow bag.

The packaging container is a cup, tray, etc. whose upper opening is heat-sealed with a sheet.

The film or sheet that is the heat-sealing material may be formed of a single layer or a plurality of layers as long as there is a layer that can be heat-sealed. The material of this heat-sealable layer may be any material as long as it can be heat-sealed, and is usually polyethylene, polypropylene, ethylene copolymer, or the like. In addition, non-crystallized polyethylene terephthalate may also be used. The thickness of the heat-sealable layer is also not particularly limited, but is usually about 3 to 200 μm, typically about 5 to 150 μm. In order to compensate for the step portion, it is necessary that the thickness of the heat-sealable layer be 20% or more of the total thickness of the material.

Multi-layer films and sheets are made by laminating two or more types of materials in order to improve printability, breakage resistance, gas barrier properties, adjust the rigidity of bag making, and improve prevention of adhesion to softened heating plates. An adhesive layer (sealant), which is a heat-sealable layer, is disposed on at least one surface layer. The surface layer material that forms the outer surface of the bag is selected from a material that does not become thermoplastic in the temperature range to which the adhesive layer is applied.

The thickness of a film or sheet consisting of multiple layers is also not particularly limited, but is usually about 20 to 200 μm, typically about 20 to 120 μm.

The width of the heat-sealed bag or container may be a normal width, generally about 3 to 20 mm, typically about 5 to 15 mm. This heat-sealing width may be the same for all the heat-sealing portions, or may be different for, for example, the top seal and the center seal.
The composite heat-seal structure formed by the heat-sealing device of the present invention consists of a strip-shaped peel-off heat seal provided in a strip-like shape with a peel-off seal, and a linear peel-off heat seal provided within the strip-shaped peel heat seal in the longitudinal direction.
In the case of a packaging bag, the peel-off heat seal band is provided on the side where the bag is to be opened, and its width is generally about 3 to 30 mm, typically about 5 to 15 mm. The adhesive strength (heat seal strength), which is peel strength, is usually about 2 to 15 N/15 mm, and generally preferably about 2 to 12 N/15 mm. By setting within this range, for example, it is possible to support easy-to-open packaging for different uses that are difficult for children to open.

The width of the filamentous seal is about 0.05 to 2 mm, preferably about 0.1 to 1.5 mm, and the depth is about 0.05 to 2 mm, preferably about 0.1 to 1.5 mm. The adhesive strength of the filamentous seal is preferably about 2 to 15 N/15 mm, preferably about 2 to 12 N/15 mm.
This filamentous seal is provided in the longitudinal direction of the strip-shaped peel-off heat seal, and is placed closer to the outer edge of the heat-sealed surface rather than in the center. It is preferable to provide it large; for example, a range of about 60 to 80% of the total width from the inner edge is appropriate.

In principle, there is one filament seal, but it is also possible to provide a plurality of filament seals, for example two or three, by increasing the local pressure bonding load within a range that does not impair the effects of the present invention.

When the heat-sealing surface is curved, it is preferable that the linear seal is provided along this curve.

The heat-sealing device of the present invention is an improvement on the heat-sealing device (Patent Document 1) that forms a composite heat-sealing structure that was previously developed by the present inventor, and the elastic body is replaced with a heating body having linear protrusions. They are moved from the opposing crimping bodies to the side of the heating body having the linear protrusions, and are placed on both sides of the linear protrusions.

The heating elements are basically the same as those in conventional heat sealing equipment, and the heating surfaces of the pair of heating elements are basically parallel, so that the entire surface is pressurized with equal pressure during heat sealing. configured and arranged. The heating surface is usually flat. The width of at least one of the heating surfaces is such that only the heat seal portion formed in the heat seal material can be heated. The other heating surface may be identical to the first heating surface, or it may be larger and serve as a base.The material may be copper, aluminum, brass or stainless steel with high thermal conductivity. used.

However, when heat sealing a cup, a tray, etc., a heating body is provided on the side that presses the lid material, and a crimping body without a heating mechanism is used on the side that receives the cup or tray.

The operating mechanism for compressing or releasing the heating element and the heat-sealing material may be the same as that of conventional heat-sealing devices, and the operation may be performed by moving only one heating element or both.

The heating mechanism for heating the heating element may be the same as that of conventional heat sealing devices, and electricity is usually used.

In a compression bonded body in which at least one side is a heating element, the linear protrusion is provided on the heating surface of the heating element, and its width and length correspond to the linear seal formed by heat sealing. Further, the cross-sectional shape is also made into a shape corresponding to the filamentous seal, such as an arcuate shape or a trapezoid. On the other hand, regarding the height, the elastic bodies disposed on both sides of the linear protrusion first generate the crimping pressure necessary for crimping the flat portion with the step. Sealing the level difference in the 2/4 plate portion with a single protrusion requires plastic deformation equal to or more than two pieces of material thickness, so this amount is also added to the crimping allowance of the flat portion. Therefore, the start of operation of the single protrusion is set at a height that precedes the plastic deformation allowance. The thickness H (mm) of the elastic body should be within the range of (1/2)H<h<H-0.1 mm.

The elastic body is used to press the flat portions under appropriate pressure, and must also have heat resistance that can withstand heat sealing temperatures, so silicone rubber, fluororubber, or the like is preferable. A plate having a shore hardness of about A40 to A90 and a thickness of about 0.5 to 8 mm, preferably about 1 to 5 mm is usually used. This thickness is set so that a compression pressure of about 0.01 to 0.4 MPa, preferably about 0.1 to 0.3 MPa, is generated during heat sealing with a compression amount within 50% of the original thickness. .

In the heat-sealing device of the present invention, during heat-sealing, the heat-sealing material is pressed against a pressure-bonding body such as a heating body, which is usually a metal surface, using linear protrusions. A stopper can be provided on the crimping surface of the crimping body. This stopper leaves a gap between the crimped bodies during crimping, and the thickness should be such that it can prevent cutting, for example, about 0.05 to 0.15 mm. The material, shape, etc. should be selected as long as they do not damage the heat-sealing material.

To move the crimping body such as a heating body back and forth, an air cylinder, a hydraulic cylinder, etc., or the addition of a spring load can be used.When these are used, crimping can be performed with a predetermined gap left, so the above-mentioned method is not possible. A stopper is normally not required and is provided for safety.

Heat-sealing conditions using the heat-sealing device of the present invention are set so that no through holes remain in the stepped portion, depending on the type and form of the heat-sealing material. At this time, it is preferable to adjust the compression pressure so that the flat portion is approximately 0.01 to 0.4 MPa, preferably approximately 0.1 to 0.3 MPa. In addition, for the striated protrusions, for example, if the load exceeds 80 N/cm for a protrusion with a width of 0.3 mm, the crimped surface will become cloudy and brittle, so the pressure should be 20 to 80 N/cm, preferably 30 to 60 N/cm. It is better to This becomes almost the same for widths of 0.2 to 0.5 mm.

Table 5 shows the relationship between the heating temperature (adhesive surface), the temperature at which adhesion is achieved, and the heat seal strength of typical plastic materials measured by the present inventor.

最短平衡温度加熱は収斂値の９８～９９％になる加熱を意味する。
ＬＤＰＥ 融点１０５～１１５℃ ビカット軟化点９５～１０９℃
ＬＬＤＰＥ 融点１１１～１３０℃ ビカット軟化点４１～８５℃
ＣＰＰ 融点１３５～１６５℃ ビカット軟化点８０～１００℃
ＯＰＰ 融点１６５℃ ビカット軟化点（１００）℃
（ ）は推定値
溶着面温度計測法；“ＭＴＭＳ”を適用し、標本の接着面に溶着面温度センサを挿入して、計測し、その温度を溶着面（接着面）温度として利用する。常温に冷却後、加熱標本の接着エッジに探傷液（“一条シール”チェッカー）を点滴する。液の浸透状態を目視（ルーペ）確認して、密封性の是非を評価。

Shortest equilibrium temperature heating means heating to 98-99% of the convergence value.
LDPE Melting point: 105-115℃ Vicat Softening point: 95-109℃
LLDPE Melting point: 111-130℃ Vicat Softening point: 41-85℃
CPP melting point 135-165℃ Vicat softening point 80-100℃
OPP melting point 165℃ Vicat softening point (100)℃
Values in parentheses are estimated values Welding surface temperature measurement method: “MTMS” is applied, a welding surface temperature sensor is inserted into the bonding surface of the specimen, the temperature is measured, and the temperature is used as the welding surface (bonding surface) temperature. After cooling to room temperature, drip the flaw detection liquid (“single seal” checker) onto the adhesive edge of the heated specimen. Check the state of liquid penetration visually (with a magnifying glass) and evaluate the sealability.

As shown in the table, CPP is 110℃, heat seal strength 0.2N/15mm, LDPE is 94℃, heat seal strength 0.1N/15mm, OPP/LLDPE is 106℃, heat seal strength 7N/15mm. , OPP/CPP achieved close adhesion at 113°C and heat seal strength of 0.4N/15mm.

Previously, it was thought that there was a strong correlation between heat seal strength and adhesion.
However, as seen in the example of OPP/LLDPE, although adhesion appears from 94°C (0.3N/15mm), adhesion is not completed at 106°C or higher. In OPP/CPP, adhesion is completed at 0.4 (N/15 mm) in the softening temperature range of 113°C. This finding indicates that the completion of adhesion is dominated by the softening temperature, which reduces the stiffness of the material.

Example 1
A heat sealing device shown in FIG. 3 was used.
This device consists of a heat bar (top) and a heat bar (bottom).The heat bar (bottom) is fixed, and the heat bar (top) is moved up and down by a drive source to compress the heat sealing material. There is.

A drive plate is attached to the lower end of the drive source, a receiving elastic body is arranged below it, and the heat bar (upper) is supported by an initial pressure setting screw to which the drive plate is attached.

The receiving elastic body changes the crimp pressure of the heat-sealing material by changing its size, and if a load device such as an air cylinder that can be precisely controlled is used as the drive source and the load is adjusted by adjusting the supply air pressure. , the receiving elastic body becomes unnecessary.

On the lower surface of the heat bar (upper), which is the heating surface of the heat-sealing material, a linear projection is formed in the center, and elastic bodies are arranged on both sides of the linear projection.

The upper surface of the heat-sealing material heating surface of the heat bar (lower) is shaved off on both sides to have a heat-sealing width W, and stoppers of the heat bar (upper) are provided at the front and rear ends. If an air cylinder or the like is used as the drive source, the stopper can be omitted.

Both the elastic body and the receiving elastic body were A50 silicone rubber plates with a thickness of 3 mm (elastic modulus: 100 N/cm ² /0.1 cm).
In order to achieve flat crimping of the 4-piece/2-piece parts, first, the pieces were compressed by 0.3 mm.
The striated projection was trapezoidal with (height h) = (3-0.3) = 2.7 mm, a width of 2 mm at the proximal end, and a width of 0.3 mm at the distal end.

The heat seal material has a surface layer of 0.03 mm OPP (melting point 165°C, Vicat softening point around 100°C) and an adhesive layer of 0.03 mm LLDPE (melting point 111-130°C, Vicat softening point 41-85°C). A two-layer film was used in the form of a pillow bag, and the heat seal was made into a width of 1 cm and a length of 10 cm. The width W1 of the receiving elastic body was 2 cm, and the length Lw was varied from 2 to 10 cm to control the crimp pressure.

In order to confirm the function of the single protrusion of the present invention, we set the sample width to 10 mm without attaching the elastic body on the heat sealing surface, changed the length Lw of the receiving elastic body, and changed the compression allowance d and the filament. Table 6 shows the results of determining the stress generated per 1 cm of protrusion.

Regarding the sealing performance by the linear protrusions, with a crimping margin of 0.3 mm width, if L is changed from 5 to 10 mm, close contact can be achieved by plastic deformation under a load of 20 to 60 N/cm.
Furthermore, it was found that if Lw=5 mm and the compression allowance was set to 0.3 to 0.7, an appropriate crimping load of 30 to 70 N/cm could be created.

Since the pillow bag has 4 center seal parts in addition to the 2 part, crimping starts from the 4 part, and when the compression allowance is around 0.2 mm, the crimping of the 2 part starts, and then the 2 part also begins. The crimping pressure of 0.2 MPa is applied at around 0.4 mm.

The actual measured value of the relationship between this compression allowance and the crimp pressure is modeled and shown in FIG.

From this study result, assuming that the compression start point at which the tip of the linear protrusion starts pushing the material is 0.3 mm, the height of the linear protrusion is (H-0.3) mm. According to actual measurements, the protrusion penetrates into the material by 0.2 mm, and during this time, the flat part is also compressed in parallel. Figure 5 shows how the compression force of the striated protrusions becomes 40 N/cm when the compression width is 0.5 mm. The pressure increase slope of the linear protrusion is selected based on the area of the receiving elastic body and the spring constant.

In this example, when the compression margin of the drive source is 0.5 mm, the load on the flat crimped part is 80 N/cm ² × 10 = 800 N, the load on the linear protrusion is 40 N/cm × 10 = 400 N, and the total load is 1200 N. . If a stopper with a thickness of 0.5 mm is installed between the heat bars (upper) and (lower), the total load can be suppressed to 1200 N and cutting due to overpressure can be avoided.

The relationship between the bonding surface temperature and the heat sealing strength (over the entire surface) of the example specimen is shown in line A in FIG. The load generated by the linear protrusion was created, and the sealing load at each heating temperature was detected by trial and error, and the relationship between the sealing and heating temperature is shown in (B). It was found that sealing was completed at 40 N/cm at around 113°C. At temperatures below 112°C, sealing could not be achieved even when 70 N/cm was applied.
It was found that the softening properties of the specimen were related. In the shrink temperature range of the surface material of 122° C. or higher, sealing is possible even with a load of 20 N/cm. It was found that sealing was difficult even under a load of 80 N/cm at temperatures below 112° C. of the peeled seal of this specimen. When OPP film is used as the surface material, it is recommended to select a sealant that peels off and forms a sealing band at 113 to 120°C.

Example 2
The apparatus shown in FIG. 7 was manufactured to seal a cup.
This device consists of a circular heat bar and a crimp pedestal for the cup. The crimp pedestal is fixed, and the circular heat bar is moved up and down by a drive source to crimp the lid material onto the cup body.

A circular drive plate is attached to the lower end of the drive source, and pressure receiving elastic bodies are arranged in a cross pattern under it to equalize the pressure.The circular heat bar is attached to the initial crimp pressure setting attached to the circular drive plate. It is supported with screws.

The receiving elastic body changes the pressure of the lid material against the cup body by changing its size, and if an air cylinder or the like is used as the driving source, the receiving elastic body becomes unnecessary.

A circular protrusion is formed on the lower surface of the circular heat bar, and elastic bodies are arranged on both sides of the protrusion.

Stoppers are provided at four locations on the periphery of the crimp pedestal. If an air cylinder or the like is used as the drive source, the stopper can be omitted.

The striated protrusions were trapezoidal with a height of 0.7 mm, a width of 0.4 mm at the proximal end, and a width of 0.2 mm at the distal end. An A50 silicone rubber plate with a thickness of 1 mm was used as the elastic body, and an A50 silicone rubber plate with a thickness of 3 mm was used as the receiving elastic body.

The cup to be heat-sealed was a commercially available product from Company A with a flange surface diameter of 65 mm and a lounge width of 3.5 mm. The cup body was made of paper impregnated with a plastic material and had a thickness of 0.4 mm, and the lid material was an aluminum laminate film with an easy-peel sealant specification and a thickness of 0.1 mm.

Heating was performed by single-sided heating from a circular heat bar. For crimping, a load of 40 N/cm was applied to the flat part with a compression margin of 0.2 mm.

FIG. 8 shows the results of measuring the heat seal strength while changing the heating temperature of the adhesive surface from 66° C. to 142° C.

As a result, the sealing of the flat part was completed at 73°C, the heat sealing strength increased, and the temperature range in which the peeling and sealing surface became uniform was around 90°C. Sealing by the linear protrusions was completed at 92°C, and the heat seal strength increased from around 110°C. On the other hand, it was found that the molten sealant began to protrude from the heat-sealed edges from around 118°C. From these results, the temperature range in which additional heat can be protected by sealing with a peelable seal is 90 to 118°C.

In the case of heating both sides at the same temperature, if the heating is performed over time, the temperature of the welded surface (adhesive surface) will converge (equilibrium temperature) at which it contacts the outer surface of the lid material.
In the case of single-sided heating, the temperature distribution within the material is approximately linear depending on the difference between (heating surface temperature)/cradle temperature, so there is a , there will be a natural temperature difference.
Results of heat sealing with the heating surface temperature of the heat bar set to 190 to 220 degrees Celsius, and measuring the response of the interface temperature (surface temperature of the elastic body) during crimping and the bonding surface temperature (with a specially prepared welding surface thermometer). is shown in FIG. 9, and Table 7 shows the detailed relationships among the heating surface temperature, interface temperature, and welding surface temperature during the compression time of 1.0 to 1.5 seconds.

As a result, for example, if the heating time is 1.3 seconds, if the heating surface temperature is 190°C, the bonding surface temperature will be 96°C, and if the heating surface temperature is 220°C, the bonding surface temperature will be 110°C. Then, the temperature falls within the appropriate heating temperature range shown in FIG.

The present invention can reliably seal even if there are steps in the formed package by adding a filament seal even to a rigid heat seal material. It can be applied to a wide range of applications, especially for cups, trays, etc.

That is, the present invention provides a heat-sealing device that performs heat-sealing by sandwiching a heat-sealing material between pressure-bonding bodies, at least one of which is a heating body, and crimping the heat-sealing material.
A linear projection protruding from the heating surface of the heating element that forms a strip-shaped peel-off seal on the heat-sealing material adds a strip-shaped peel-off seal in the longitudinal direction of the strip-shaped peel- off seal. The present invention provides a heat-sealing device forming a composite heat-sealing structure , characterized in that an elastic body is arranged on the heating surface on both sides of the linear protrusion.

That is, the present invention provides a heat-sealing device that performs heat-sealing by sandwiching a heat-sealing material between pressure-bonding bodies, at least one of which is a heating body, and crimping the heat-sealing material.
A filamentous protrusion that adds a filamentous peel-off seal in the longitudinal direction of the strip-shaped peel-off seal protrudes from the heating surface of the heating body that forms a strip-shaped peel-off seal on the heat-sealing material. The present invention provides a heat seal device for forming a composite heat seal structure, characterized in that elastic bodies are arranged on the heating surfaces on both sides of the linear protrusions.

Claims (4)

In a heat sealing device that performs heat sealing by sandwiching and pressing a heat sealing material between crimping bodies, at least one of which is a heating body, a linear protrusion is provided on the heating surface of the heat sealing material of the heating body; A composite heat-seal structure is formed in which a strip-shaped peel-off seal is added in the longitudinal direction of the strip-shaped peel-off seal, which is characterized by an elastic body being placed on the heating surface of the heat-seal material on both sides of the striated projections. Heat sealing device The height h (mm) of the linear protrusion is in the range of (1/2)H<h<H−0.1 mm of the thickness H (mm) of the elastic body installed on both sides. heat sealing device A method for heat sealing using the heat sealing device according to claim 1, characterized in that the pressure of the flat surface of the heat sealing material is 0.01 to 0.4 MPa. The heat sealing method according to claim 3, wherein the heat sealing material is a cup or a tray.

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