JP2001232276A - Method for coating by hot-melt discharging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating by hot-melt discharging which surely prevents stringing (angel hair) of a hot-melt material from remaining on a material to be coated when the hot-melt material is applied on the circumference of the rotating material to be coated. SOLUTION: This is a method for applying a heat-melted hot-melt material 5 on the circumference of a rotating paper container. In this method, timing control is performed in such a manner that the rotation of the paper container is stopped simultaneously or the rotation of the paper container is already stopped when discharge of the hot melt material 5 is stopped, in the case of coating by discharging the hot-melt material 5 to a seam crevasse 4 of the paper container from the discharge nozzle 8 of a gun-discharge-type hot melt applicator 7 while the paper containers rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stringing (angel hair) when a hot-melt material is heated and melted, discharged from a hot-melt gun (discharge nozzle), and the object is rotated while being applied in a circumferential shape. The present invention relates to a hot-melt discharge coating method for preventing the occurrence of (1).

[0002]

2. Description of the Related Art In the case of aseptically filling a beverage or food into a container, it is necessary to sterilize the beverage or the like and the container in advance, fill the sterilized container with the beverage or the like in a sterile atmosphere, and seal the container. .

When a cup-shaped paper container is used as this container, a seam crepas, which is an annular gap, is formed inside the fixed portion between the bottom wall and the side wall of the paper container. There is a problem that the disinfectant hardly adheres to the seam crep, and thus disinfection tends to be insufficient.

[0004] Therefore, the present inventors have conceived of embedding this seam crepe with a molten hot melt material so that sterilization with a germicide can be easily performed.

However, when the hot-melt material melted by heating is discharged from the hot-melt gun and applied to the seam crepe of the rotating paper container, a thin hot-melt material such as a thread is applied from the surface of the hot-melt material applied to the seam crepe. Melt material may be generated.

[0006] This phenomenon is called stringing or angel hair. Since this long thread-like object is easily released, it is desired not to cause this stringing.

On the other hand, the following means are known as means for preventing the occurrence of stringing when hot-melt material is melt-coated ("Handbook of Packaging Technology", July 1, 1995).
Published by Japan Packaging Technology Association). When the viscosity of the hot melt material at the use temperature is high, the melting temperature of the hot melt material is increased to lower the viscosity and improve the cut at the time of discharge. As the distance from the discharge gun to the object to be coated increases, stringing tends to occur. Therefore, the discharge gun is moved closer to the object to be discharged. Raise the discharge pressure of the discharge gun to improve the cut during discharge. Selection of hot melt material that is difficult to string. Use a low viscosity hot melt material.

[0008]

However, the hot melt material is heated and melted and discharged from the hot melt gun.
When applying to the circumference while rotating the workpiece, the rotating motion of the workpiece is involved, so even if a hot-melt material that is unlikely to be generated by normal discharge is selected, Even if a good ejection method is adopted, stringing is likely to occur.

That is, when the object to be coated is accompanied by a rotational movement, the reason why the threading object remains on the object to be coated is that the threading object generated at the time of gun ejection acts on the pulling force in the rotating direction or the radial direction. It is presumed that the particles are scattered and cooled by the centrifugal force, and the stringing material remains on the object to be coated.

A hot-melt material used for filling a seam crep of a paper container with a molten hot-melt material has a strength that does not break when the paper container is handled, and is used for filling, sealing, transporting and the like of contents. Since flexibility is required so that a certain degree of deformation can be achieved integrally with the container body, it is impossible to reduce the viscosity too much as a result of increasing the resin component.

Therefore, when the object to be coated is to be applied in a circumferential shape while rotating the object, even if the above-described means for preventing the occurrence of stringing is adopted, the object to be coated is not However, there is a problem that it is not possible to surely eliminate the residual.

On the other hand, if the threaded material of the hot melt material remains on the inner surface side of the beverage container or the food container, the threaded material is easily peeled and easily cut, so that the consumer swallows with the beverage or food. There is a possibility that it is not preferable in terms of food hygiene, and in particular, in the case of beverage containers and food containers, there is a background that it is necessary to meet the demand for preventing stringing.

The present invention has been made in view of the above-mentioned conventional problems and demands. When a hot melt material is circumferentially applied while rotating an object to be coated, the threading material remains on the object to be coated. It is an object of the present invention to provide a hot-melt discharge coating method capable of reliably eliminating the problem.

[0014]

According to the first aspect of the present invention, there is provided a method of circumferentially applying a hot-melt material melted by heating to an object to be coated, wherein the hot-melt material is rotated while rotating the object to be coated. When the hot-melt material is discharged from the gun and applied to the object, when the discharge of the hot-melt material is stopped, the rotation of the object is simultaneously stopped or the rotation of the object is already stopped. The control is performed.

According to a second aspect of the present invention, in the hot melt discharge coating method according to the first aspect, the discharge of the hot melt material is started at the same time as the rotation of the object is started, and the rotation time of the object is set to a hot time. It is characterized in that timing control is performed by time management that is equal to or shorter than the melt discharge time.

According to a third aspect of the present invention, in the hot melt discharge coating method according to the first or second aspect, the object is circularly formed by winding a lower end of a cylindrical body around a side wall of a circular bottom. The bottom and the cylindrical body are integrated into a paper container for beverages and foods, and the portion where the hot melt material is applied in a circular shape is the circular bottom of the paper container and the cylindrical body at the container inner surface. It is characterized by a seam crape that touches.

According to a fourth aspect of the present invention, in the hot melt discharge coating method according to any one of the first to third aspects, the hot melt material is a low-viscosity composition containing polyethylene and paraffin wax as main components. Features.

[0018]

According to the first aspect of the present invention, the hot-melt material that has been heated and melted is discharged from the hot-melt gun and applied to the rotating object. The hot melt material can be applied in a circumferential shape. When applying this hot melt material, when stopping the discharge of the hot melt material from the hot melt gun,
Timing control is performed to simultaneously stop the rotation of the object to be applied or to stop the rotation of the object to be applied.
That is, at the time of stopping the discharge of the hot melt material, a stationary state in which the rotation of the object to be coated is momentarily stopped is realized, and similarly to the case of the spot coat in the stationary state,
Since the threading material generated at the time of gun ejection is pulled and melted by the applied hot melt material, the threading material does not remain on the object to be coated.

According to the second aspect of the present invention, when applying the hot melt material, the discharge of the hot melt material is started at the same time as the rotation of the object is started, and the rotation time of the object is reduced by the hot melt. Timing control is performed by time management that is equal to or shorter than the ejection time. That is, the time for applying the hot melt material to the object mass-produced on the production line is a very short time of, for example, 300 msec. For this reason, if the timing at which the discharge of the hot melt material is stopped and the timing at which the rotation of the object is stopped are made to coincide with each other, or if a slight shift of, for example, about 50 msec is attempted, high-precision timing by high-speed processing is required. Control will be required. On the other hand, the rotation of the object to be coated and the start of the discharge of the hot melt material are simultaneously performed, and the rotation time of the object to be coated from the start of the rotation to the stop of the rotation and the hot melt discharge time from the start of the discharge to the stop of the discharge are, for example, the same. When the time is set, simultaneous timing is achieved, and when the hot melt discharge time is made longer than the rotation time of the object to be coated, advance stop of the object to be coated is achieved. Desired timing control can be performed.

According to the third aspect of the present invention, the object to be applied to the hot melt discharge coating method is such that the lower end portion of the cylindrical body is wound around the side wall of the circular bottom and the cylindrical bottom is connected to the cylindrical body. It is a paper container for beverages and foods with integrated parts, and the part to which the hot melt material is applied in a circumferential shape is a seam crepe where the circular bottom part of the paper container and the cylindrical body contact the inner surface of the container. . That is, paper containers for beverages and foods are formed with a seam crep as an inner annular gap in the container.For example, when sterilizing a container, even if there are hygienic unfavorable bacteria in the seam crep, a sterilizing solution is used. However, it does not completely reach the seam crepasse due to the narrow gap, and it is impossible to sterilize it reliably. Therefore, the hot melt material is buried in this seam crepas, but if stringing material that is easily peeled or cut remains,
Unfavorable for food hygiene On the other hand, by adopting a hot melt discharge coating method in which no threading material remains, it is possible to manufacture paper containers for beverages and foods which are preferable from the viewpoint of food hygiene.

According to the fourth aspect of the present invention, the hot melt material applied to the hot melt discharge coating method is a low viscosity composition containing polyethylene and paraffin wax as main components. Therefore, since the composition contains paraffin wax having one of the effects of lowering viscosity as one of the main components, the viscosity can be reduced to a level at which the hot melt gun discharge method is possible. Further, since the composition contains polyethylene as a resin component as one of the main components, for example, in the case of a paper container, the embedded hot melt material and the container body can be integrally deformed to some extent, and the paper container The required flexibility can be secured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

(Embodiment) FIG. 1 is a partially cutaway front view showing a paper container (an example of an object to be coated) manufactured by the hot melt discharge coating method according to the present embodiment, and FIG. FIG. 2 is an enlarged cross-sectional view of a portion A in FIG. 1 illustrating a seamed clevis and a tightened portion of the paper container manufactured by the method of FIG.

This paper container has a circular bottom 2 which constitutes the container.
As the material of the cylindrical body 1, a laminated material mainly composed of paper and having plastic layers laminated on both sides is used. That is, in order from the inner surface side, a linear low-density polyethylene layer of 40 μm / a low-density polyethylene layer of 15 μm /
12 μm aluminized polyethylene terephthalate film layer / 15 μm low density polyethylene layer / 15
The circular bottom portion 2 and the cylindrical body 1 are made of a constituent material of a low-density polyethylene layer of μm / a paper (290 g / m ² ) layer / a medium-density polyethylene layer of 20 μm.

Then, the side wall 2a is bent down from the peripheral edge of the circular bottom portion 2, and the inner surface of the side wall 2a and the lower portion of the inner surface of the cylindrical body 1 are heat-bonded by melting the laminated plastic layer. The lower end 1a of the cylindrical body 1 is bent inward so as to wrap the inner surface of the side wall 2a of the bottom 2, and the inner surface of the lower end 1a and the outer surface of the side wall 2a are thermally bonded by melting of the laminated plastic layer. The circular bottom 2 and the cylindrical body 1 are integrated in a state in which the side wall 2a of the circular bottom 2 is fastened by the cylindrical body 1 (winding portion 3).

At a portion where the circular bottom 2 and the cylindrical body 1 are in contact with each other on the inner surface of the container, a wedge-shaped annular cut is formed between the inner surface of the cylindrical body 1 and the bent surface of the side wall 2a. A seam crepe 4 is formed as a gap, and the seam crepe 4 is filled with a hot melt material 5 of a thermoplastic mixture mainly containing polyethylene and paraffin wax.

The dimensions of the paper container are 50 mm in height, 60 mm in outer diameter at the upper end, and 52 mm in outer diameter at the lower end. The quality of the container body was evaluated by leaching with highly permeable orange oil. Inspections were conducted, and it was confirmed that there was no particular problem with quality.

FIG. 3 is a schematic view showing an apparatus for filling a seam crepe 4 of a paper container by the hot melt discharge coating method in the embodiment. As shown in FIG. 3, a cup-shaped paper container is placed on a turntable (not shown) that can rotate horizontally. Then, a gun discharge type hot melt applicator 7 is disposed at an upper position of the paper container, and a seam clevis 4 is formed by a discharge nozzle (hot melt gun) 8 of the applicator 7.
The hot-melt material 5 is discharged to the target. Note that FIG.
, 9 is a tank, 10 is a pump, and 11 is a hose.

Next, the operation will be described.

[Hot Melt Discharge Coating Method] The hot melt material 5 is heated (for example, 130 ° C.) in the tank 9, pressurized by a pump 10 and supplied to a gun discharge hot melt applicator 7. After the temperature is raised (for example, 200 ° C.), the hot melt material 5 is applied from the discharge nozzle 8 toward the rotating seam crepe 4 of the paper container so as to fill the circumferential seam crepe 4. Can be applied.

When the hot melt material 5 is applied, when the discharge of the hot melt material 5 from the discharge nozzle 8 is stopped, the rotation of the paper container is simultaneously stopped, or the rotation of the paper container is already stopped. Timing control is performed.

That is, when the discharge of the hot melt material 5 is stopped, a stationary state (rotation stop time zone) in which the rotation of the paper container is momentarily stopped is realized. Similarly to the above, the stringing material generated at the time of discharge from the discharge nozzle 8 is pulled and melted by the applied hot melt material 5 having a high temperature, so that the stringing material does not remain in the paper container.

[Timing Control by Time Management] In the above-mentioned timing control, when applying the hot melt material 5, the discharge of the hot melt material 5 is started at the same time as the rotation of the paper container is started. It is performed by time management to make the melt discharge time or less.

That is, the time for applying the hot melt material 5 to the paper containers mass-produced on the production line is a very short time of, for example, 300 msec. For this reason, if the timing at which the discharge of the hot melt material 5 is stopped and the timing at which the rotation of the paper container is stopped are made to coincide with each other, or if a slight shift of, for example, about 50 msec is attempted, high-precision timing by high-speed processing is performed. Control will be required.

On the other hand, the rotation of the paper container and the start of the discharge of the hot melt material 5 are simultaneously performed, and the rotation time of the paper container from the start of the rotation to the stop of the rotation and the hot melt discharge time from the start of the discharge to the stop of the discharge are, for example, , 300 msec, the same timing is achieved. Simultaneous timing is achieved. Further, when the paper container rotation time is 250 msec and the hot melt discharge time is 300 msec, the paper container is prematurely stopped. With simple control that does not require the above, it is possible to perform timing control that gives a slight time difference of about 50 msec.

[Application of Paper Container to Seam Crepas] In the present embodiment, the object to be applied to the hot melt discharge coating method is such that the lower end portion 1a of the cylindrical body 1 is attached to the side wall 2a of the circular bottom portion 2. A paper container for beverages and foods is formed by unifying the circular bottom portion 2 and the cylindrical body portion 1 into a unit, and the portion to which the hot melt material 5 is applied in a circumferential shape is the circular bottom portion 2 of the paper container and the cylindrical body portion. Part 1
Is a seam crepass 4 that contacts the inner surface of the container.

That is, in the paper container for beverages and foods, the seam crepe 4 which is an inner annular gap is formed in the container. For example, when the container is sterilized, various bacteria which are not hygienic in the seam crepe 4 exist. However, the sterilizing solution does not completely reach the seam crep 4 due to the narrow gap, so that it is impossible to sterilize reliably. Therefore, as shown in FIGS. 1 and 2,
Although the hot melt material 5 is buried in the seam crepe 4, it is not preferable from the viewpoint of food hygiene if a stringed material that is easily peeled or cut remains.

On the other hand, by adopting a hot melt discharge coating method in which the above-mentioned paper container rotation time is set to be equal to or shorter than the hot melt discharge time and no string is left, a paper container for beverages and foods which is preferable from the viewpoint of food hygiene is manufactured. can do.

[Selection of Hot Melt Material] In the embodiment, the hot melt material 5 applied to the hot melt discharge coating method is a low-viscosity composition containing polyethylene and paraffin wax as main components.

Therefore, since the composition contains paraffin wax, which has an effect of lowering viscosity, as one of the main components,
The viscosity can be reduced to a level at which the hot melt gun discharge method is possible.

Further, since the composition contains polyethylene as a resin component as one of the main components, for example, in the case of a paper container, the buried hot melt material 5 and the container body can be deformed to some extent, The flexibility required for the paper container can be secured.

Next, the effects will be described. (1) At the time of applying the hot melt material 5, when the discharge of the hot melt material 5 from the discharge nozzle 8 is stopped, the rotation of the paper container is simultaneously stopped or the timing control for stopping the rotation of the paper container is performed. As a result, a stationary state in which the rotation of the paper container is stopped instantaneously is realized, and the stringing material generated at the time of discharge from the discharge nozzle 8 is pulled by the high-temperature hot-melt material 5 applied and melted. Therefore, it is possible to prevent the string from remaining in the paper container. (2) When applying the hot melt material 5, the discharge of the hot melt material 5 is started at the same time as the rotation of the paper container is started, and the timing control is performed by time management so that the paper container rotation time is equal to or less than the hot melt discharge time. Since the control is performed, the timing can be controlled so as to have a slight time difference by simple control that does not require high-speed processing. (3) The lower end 1a of the cylindrical body 1 is wound around the side wall 2a of the circular bottom 2 so that the object to be applied in the hot melt discharge coating method is integrated with the circular bottom 2 and the cylindrical body 1. The paper container for beverages and foods, and the portion to which the hot melt material 5 is applied in a circular shape is a seam crep 4 in which the circular bottom portion 2 and the cylindrical body 1 of the paper container are in contact on the inner surface of the container. The sterilization of the paper container can be achieved, and the paper container for beverages and foods which is preferable from the viewpoint of food hygiene can be produced without leaving the stringed material. (4) Since the hot-melt material 5 applied to the hot-melt discharge coating method is a low-viscosity composition containing polyethylene and paraffin wax as main components, the low-viscosity can be achieved by the hot-melt gun discharge method. Therefore, the flexibility required for the paper container can be secured.

(Examples 1 to 6 and Comparative Examples 1 to 3) Examples 1 to 5 and Comparative Examples 1 to 3 which support the effect of the hot melt discharge coating method of the present invention will be described.

The object to be coated used in the investigation was a laminated material mainly composed of paper and a plastic layer laminated on both sides. The laminated material had the same laminated structure as the material used for the paper container, and was formed into a circular shape having a diameter of 58 mm. 80 pieces were prepared.

The hot-melt material used in the investigation was 45 parts of low-density polyethylene (trade name "JMA07A" manufactured by Nippon Polyolefin Co., Ltd.) and paraffin wax (paraffin wax having a melting point of 60 ° C. manufactured by Nippon Seirowa Co., Ltd.). ) 5
And 5 parts. The viscosity was 1000 centipoise at 200 ° C.

This hot melt material is placed in a tank at 130 ° C.
To a gun-discharge type hot melt applicator.
After the temperature is increased, a circle having a diameter of about 52 mm is drawn from the discharge nozzle having a diameter of about 0.3 mm on the circular laminated material rotating at a rotation speed of 250 rpm (rotation / minute). On the circumference.

When the hot melt material is applied as described above, the distance between the object and the tip of the discharge nozzle, the application amount, the discharge pressure of the hot melt material, and the rotation time of the object are changed. Examples 1 to 6 and Comparative Examples 1 to 3 investigated whether stringing occurred. The discharge time of the hot melt material is 300 msec (millisecond or millisecond) in each case. FIG. 4 shows the results.

From the comparison between Examples 1 to 4 and Comparative Examples 1 and 2 in FIG. 4, there is almost no effect of preventing stringing by shortening the distance between the object and the discharge gun. Further, Examples 1 to
2 and Examples 5 to 6 and Comparative Examples 1 and 3 show that:
There is almost no effect of preventing stringing by changing the discharge pressure of the hot melt material. Further, from a comparison between Examples 1 to 6 and Comparative Examples 1 to 3, although a lot of stringing is observed when the hot melt material discharge time is shorter than the rotation time of the object to be coated, the hot melt material discharge time is reduced. By setting the applied material rotation time or longer, no stringing was observed.
It was proved that the stringing prevention effect was high.

(Examples 7 to 10 and Comparative Examples 4 and 5) In Examples 1 to 6 and Comparative Examples 1 to 3, a circular laminated material was used as an object to be coated. Examples 4 and 5 are examples in which the paper container shown in FIGS.

That is, a bottomed paper container on a cup having a height of 50 mm, an outer diameter of an upper end portion of 60 mm, and an outer diameter of a lower end portion of 52 mm was manufactured. And the distance between the paper container (object to be coated) and the tip of the discharge nozzle using the same hot melt material as in Comparative Examples 1 to 3,
Examples 7 to 10 and Comparative Examples 4 to 5 investigated whether stringing occurred or not by changing the amount of application, the discharge pressure of the hot melt material, and the paper container rotation time. The result is shown in FIG.

From the comparison between Examples 7 to 8 and Comparative Example 4 and Examples 9 to 10 and Comparative Example 5 in FIG. 5, the distance between the object to be coated and the tip of the discharge nozzle was changed from 80 mm to 50 mm.
Even if the rotation speed of the paper container is changed from 400 rpm to 250 rpm, there is almost no effect of preventing stringing.

On the other hand, from the comparison between Examples 7 to 10 and Comparative Examples 4 and 5, when the hot-melt material discharge time is 300 msec and the rotation time of the object to be coated is 600 msec, although stringing is observed in most of the samples, The hot melt material discharge time and the object rotation time are the same for 300 ms.
c or the hot melt material discharge time is 300 msec.
Assuming that the rotation time of the object to be coated was 250 msec, no stringing was observed in all the specimens, demonstrating that the stringing prevention effect was high.

(Other Embodiments) In the above embodiment, an example of application to a paper container as an object to be coated has been described. The present invention can be applied not only to paper containers but also to various objects to be coated.

In the embodiment, as the hot melt material,
The mixing ratio of polyethylene resin and paraffin wax is
An example in which the mixing ratio is 45:55 by weight is shown. However, if the resin content is too large, the melting temperature becomes high, and the nozzle diameter needs to be increased, and the discharge pressure needs to be increased. Stringing is likely to occur. On the other hand, if the amount of the paraffin wax is too large, the flexibility of the hot melt material is reduced and cracks are easily generated. Therefore, the mixing ratio of polyethylene and paraffin wax is preferably 5 by weight.
5:45 to 25:75, particularly preferably 45:55 to
35:65.

In the present embodiment, low-density polyethylene is used as the resin of the hot melt material. However, linear low-density polyethylene can also be used. Depending on the resin used, other polyolefin resins such as polyethylene and polypropylene can be appropriately selected.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a paper container (an example of an object to be coated) manufactured by a hot melt discharge coating method according to the present embodiment.

FIG. 2 is an enlarged cross-sectional view of a portion A in FIG. 1 showing a seamed crevice and a seam crest of a paper container manufactured by the method according to the present embodiment.

FIG. 3 is a schematic view showing an apparatus for filling a seam crep of a paper container by a hot melt discharge application method in the embodiment.

FIG. 4 is a diagram showing a survey result table of Examples 1 to 5 and Comparative Examples 1 to 3, which confirm the effect of the hot melt discharge coating method.

FIG. 5 is a table showing the results of surveys of Examples 7 to 10 and Comparative Examples 4 and 5, which support the effects of the hot melt discharge coating method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical trunk part 2 Circular bottom part 3 Winding part 4 Seam crepass 5 Hot melt material 7 Gun discharge type hot melt applicator 8 Discharge nozzle (hot melt gun) 9 Tank 10 Pump 11 Hose

Claims (4)

[Claims] 1. A method of circumferentially applying a hot-melt material melted by heating to an object to be coated, wherein the hot-melt material is discharged onto the object from a hot-melt gun while rotating the object to be coated. When applying and applying, hot melt discharge coating is characterized in that when the discharge of the hot melt material is stopped, the rotation of the object to be coated is simultaneously stopped or the timing control is performed to stop the rotation of the object to be coated already. Method. 2. The hot melt discharge coating method according to claim 1, wherein the discharge of the hot melt material is started at the same time as the rotation of the object is started, and the rotation time of the object is set to be equal to or shorter than the hot melt discharge time. A hot melt discharge coating method characterized by performing timing control by time management. 3. The hot melt discharge coating method according to claim 1, wherein the lower end portion of the cylindrical body is wound around a side wall of a circular bottom to form a round bottom and a cylindrical body. And a paper container for beverages and foods in which the hot-melt material is applied in a circular shape to an inner annular gap (hereinafter referred to as an inner space) in which the circular bottom portion and the cylindrical body of the paper container are in contact with the inner surface of the container. Hot-melt discharge coating method. 4. The hot melt discharge coating method according to claim 1, wherein the hot melt material is a low-viscosity composition containing polyethylene and paraffin wax as main components. Coating method.