JP6409340B2 - Resin coating method and apparatus - Google Patents

Description

  The present invention relates to a coating method and a coating apparatus for coating a local region of an object with a coating material mainly composed of a synthetic resin (hereinafter simply referred to as a resin).

As a means for coating a portion of an object with a resin, a method of coating a molten resin by discharging it with a hot melt gun is generally performed. However, applicable resins are limited and the application range is narrow. Further, since a stringing phenomenon of the resin occurs after discharging from the nozzle, there is a problem that it is difficult to accurately cover a narrow region, the resin is wasted, and the cycle up is difficult. The use of a hot runner instead of a hot melt gun widens the applicable resin range, but the same stringing phenomenon occurs. In addition, there are wet methods such as resin solution coating and emulsion coating, but there are problems that the material is limited and the solvent has to be vaporized after coating, and the environmental load of the solvent is high. Furthermore, a method of forming a film by injecting molten resin, which is extruded and melted with a screw while heating a resin raw material in the same manner as an injection molding machine, onto a surface of an object such as metal is formed (Patent) Reference 1). Although this device is suitable for resin coating on the surface of a large object, accurate intermittent injection of a small amount of resin is difficult. For example, a small amount of resin is placed on the stepped portion of an opening curl portion such as a paper cup. However, it is difficult to apply, and it is difficult to reduce the size and speed of the apparatus, and the equipment cost is high.
In addition, as another method, it is also known that an adhesive resin powder is coated on the surface of an object by flame spraying using a flame of acetylene, propane or the like with a spray gun (see Patent Document 2). However, in this case as well, intermittent treatment and spray pattern control are difficult, and reliable spray coating on a narrow region is difficult, and the object and the coating resin itself may be thermally deteriorated by a flame.
As described above, for products that are conventionally transported on a transport line and industrially mass-produced, a resin film mainly composed of synthetic resin is partially intermittently accurately and efficiently in a particularly narrow area. It can be said that the technology to form is not yet established.

JP 09-201833 A JP-A-63-141666

  Therefore, an object of the present invention is to provide a resin coating method and apparatus capable of accurately and efficiently coating a resin even in a narrow region of an object and intermittently and repeatedly performing resin coating.

The resin coating method of the present invention for solving the above problems is a coating method for coating a local region of a paper container with a coating material mainly composed of a synthetic resin, and the local region in which the resin coating of the paper container is planned The local region is preheated by blowing hot air on it , and the powder mainly composed of the synthetic resin is cut out in a fixed amount and pumped by a pressurized gas, and the powder is mainly composed of the above synthetic resin by being joined to the heated gas that is hot air. The body is heated near the melting point, partially melted, and intermittently sprayed onto the local region.
In the thermal spraying, the powder can be repeatedly applied to the target in small amounts by cutting the powder into a fixed amount and heating and intermittently spraying the powder onto the local region.
The powder is heated by hot air near the melting point of the synthetic resin and partially melted . Furthermore, the object is not heated in a completely melted state by preheating the local area to be coated, but the injected resin powder is completely melted on the surface of the object to cover the surface of the object. Therefore, there is no occurrence of the stringing phenomenon, the cycle of intermittent spraying can be increased, and the coating efficiency can be increased.
As the object of the resin coating, the resin is applied to the bonding step portion of the opening curl portion of the container having the opening, the resin coating of the exposed paper edge of the paper container, or the modification for the purpose of local modification of the object. The present invention can be easily applied to a resin coating or the like in which a powder obtained by mixing a material with the synthetic resin powder is thermally sprayed locally.
In addition, it is possible to perform resin filling for the purpose of imparting shape retention and rigidity to a molded body provided with a three-dimensional shape by embossing, overhanging, drawing, or the like.

The resin coating apparatus of the present invention that solves the above problems is a coating apparatus that sprays a powder mainly composed of synthetic resin on a local area of a paper container to cover the local area, and the powder is supplied to the local area. A thermal spray nozzle communicating with the lower end of the tank, a quantitative cutout shutter device provided between the lower end opening of the tank and the thermal spray nozzle , and a preheating means ,
Preheat the local region of the paper container with the preheating means,
Cut out a fixed amount of powder from the tank with the fixed amount cutout shutter device ,
As a heating means, air is heated to a heated gas that is heated air, and the powder is heated in the vicinity of the melting point to be partially melted and intermittently sprayed from the spray nozzle to the preheated local region. It is characterized by.

The quantitative cut-out shutter device comprises a rotating body that traverses the outlet opening of the tank. The rotating body is provided with a measuring chamber facing the outlet opening of the tank, and communicates with a gas supply port of the measuring chamber. A valve for supplying pressurized gas to the metering chamber, the rotating body being capable of intermittent rotation between the metering position and the spraying position, facing the outlet opening of the tank at the metering position; It is possible to adopt a configuration in which a fixed amount of powder is measured, the measuring chamber faces the spray nozzle at an injection position, and pressurized gas is supplied from the valve to the measuring chamber to press the powder to the spray nozzle. .
When the heating gas is hot air obtained by heating air with a heating unit, the thermal influence on the object can be reduced as compared with thermal spraying by a flame.

According to the coating method of the present invention, resin coating can be accurately and efficiently performed even in a small area by intermittently spraying a powder mainly composed of synthetic resin on a local region.
In addition, by intermittently cutting and spraying a powder mainly composed of synthetic resin, it becomes possible to spray a small particle size material with high welding efficiency to a small area, and it is efficient with the minimum amount of material used. The resin can be well coated and high cycle can be achieved.
Further, in the thermal spraying, the synthetic resin powder is heated by hot air in the vicinity of the melting point thereof and partially melted, so that it melts after adhering to the object, so that resin stringing is eliminated and high-speed intermittent injection can be performed accurately.
The object is preheated in the local region to be coated with the resin, so that the resin powder sprayed in a state of being partially melted by heating near the melting point can be efficiently welded in the local region.
According to the coating method of the present invention, it is possible to apply a small amount of resin to the stepped portion by applying it to the bonding stepped portion of the opening curled portion of the container having the opening, and directly drink the contents from the container. In addition, it is possible to improve the mouth-feel and to improve the sealing performance at the stepped portion when the lid material is heat-sealed. In addition, leakage from the step portion when the container is sealed with an overcap can be effectively prevented.
According to the coating method of the present invention, the exposed paper edge can be effectively coated with resin by applying it to the exposed paper edge such as the overlapping portion of the paper container. Water resistance can be improved.
According to the coating method of the present invention, it can be applied to a paper molded body having low rigidity, and a local buildup as a reinforcing material can be added to the molded body, thereby improving the rigidity and shape retention of the molded body. can do.
According to the coating method of the present invention, for example, by mixing a powder such as an inorganic substance in the powder resin and applying it locally to a paper container that is likely to be burned when heated in a microwave oven, It can be modified so that it does not easily burn.

The coating apparatus of the present invention has a simple structure and can be reduced in size, can be easily and inexpensively incorporated into a normal production line, and even if the sprayed area is a small area, a small amount of powder The resin can be sprayed accurately and intermittently, and the material used can be reduced.
In addition, the coating apparatus of the present invention has a preheating means for preheating the local region, so that the powder resin is thermally sprayed in a partially heated state near the melting point and completely sprayed on the surface of the object. Thus, the surface of the object can be melted and coated, so that the stringing phenomenon does not occur and the cycle of intermittent spraying can be increased and the coating efficiency can be increased.
In addition, the coating apparatus of the present invention includes the quantitative cutout shutter device according to claim 7 so that even a small amount of powder resin can be accurately measured with a simple mechanism, and intermittently. It can be done at high speed. As a result, it is also possible to apply a powder having a small particle size that makes sliding property poor.
Furthermore, by using hot air as the heated gas, thermal spraying can be performed without using a flame, and the thermal influence of the object and the coating resin itself can be mitigated.

(A)-(c) is a schematic diagram which shows typically the principal part and coating method of the coating | coated apparatus of this invention. (A) (b) is a schematic diagram at the time of compressing and filling powder into a measurement chamber in the apparatus of FIG. 1 is a paper cup of a paper container to which the present invention is applied, (a) a perspective view thereof, (b) is a sectional view taken along line II in (a), and (c) is a B part of an annular leg portion in (a). It is sectional drawing. It is the photograph which put the resin on the lamination base paper of Example 1 of this invention, (a) Cross section, (b) Top view. The coating method which concerns on embodiment of this invention is shown, (a) is a preheating process, (b) is a thermal spraying process. It is the photograph which put the resin on the level | step-difference part of Example 2 of this invention, (a) Top view, (b) Sectional drawing, (b-1) shows the enlarged view of the level | step-difference part in (b).

Hereinafter, embodiments of a coating method and a coating apparatus according to the present invention will be described in detail with reference to the drawings.
The present invention relates to a coating method and a coating apparatus for coating a local region of an object such as a paper cup with a coating material mainly composed of resin powder. In the present invention, a powder mainly composed of synthetic resin is quantitatively cut out and synthesized as a method that enables high-speed and reliable resin coating without causing a stringing phenomenon with a small amount of resin in a small area of the object. It was heated to the vicinity of the melting point of the resin and sprayed repeatedly on the local area intermittently. As the synthetic resin powder, the resin material and its particle size are selected according to the local application / purpose covered with the synthetic resin. For example, the resin material is sprayed on the stepped area of the opening curl portion of the cup, which will be described later. In this case, a heat-sealable resin powder such as polyethylene is used in order to improve the sealing performance by eliminating the stepped portion and heat-sealing with the lid material.

  FIG. 1 schematically shows an essential part of a resin coating apparatus for spraying a powder resin to a local region, and is sprayed to a lower end opening 11 of a hopper-like tank 1 via a quantitative cutting apparatus 2. A nozzle 3 is provided. Connected to the tank 1 is a powder supply device 12 for supplying powder mainly composed of resin to the tank. Moreover, a heating means for heating the supplied powder resin to a predetermined temperature can be provided as necessary. As the heating means, a hot air generator is preferable.

The fixed quantity cutout shutter device 2 includes a rotating body 20 that traverses the lower end opening 11 of the tank 1, faces the lower end opening 11 of the tank 1 to the rotating body 20, and the top reaches the substantially central axis of the rotating body 20. A conical hollow measuring chamber 21 is provided. One end of the rotating body 20 is connected to intermittent rotation driving means (not shown), and has a channel 22 having one end connected to a pressurized gas source along the central axis, and the channel is a measuring chamber. It communicates with a pressurized gas supply port 24 formed at the top of 21. A supply line 23 connected to a compressed air supply source such as a compressor is connected to the flow path 22, and an electromagnetic valve 25 provided in the supply line controls the timing of feeding pressurized gas into the measurement chamber. . The rotating body 20 is intermittently half-rotated and controlled so that the metering chamber is alternately positioned at the powder metering position and the pressure feeding position to the spray nozzle.
A heating gas is supplied to the thermal spray nozzle as a heating means. The heated gas is preferably hot air, and is heated to a predetermined temperature by heating means such as electric or gas combustion by a hot air generator 33 connected to an air supply source such as a compressor and supplied to the spray nozzle.

  The thermal spray nozzle 3 has an introduction flow channel 31 for receiving the powder resin from the measuring chamber 21 when the rotating body 20 rotates to the thermal spray position at the top, and an injection flow channel 32 having a predetermined diameter is formed below the flow channel. ing. A heating gas is supplied to the injection flow path, and the heating gas merges with the powder pressure-fed from the measurement chamber. As a matter of course, the rotary body 20 is rotatably connected in a sealed state between the tank 1, the quantitative cutout shutter device and the thermal spray nozzle so that the powder does not leak outside.

The powder resin coating apparatus of the present invention is configured as described above, and performs resin coating by spraying the powder resin onto a predetermined region of the object as follows.
First, the resin coating planned area | region of a target object is preheated. The preheating is not particularly limited, and various heating methods can be adopted. However, in order to heat a partially simple and inexpensive facility, hot air is supplied from the preheating nozzle 4 as shown in FIG. It is preferable to spray. Moreover, preheating can also be performed by using hot air from a thermal spray nozzle and delaying resin injection. By preheating the surface to be sprayed, even if the resin sprayed from the spray nozzle is not completely melted, the resin is well welded to the surface of the object, and a resin coating can be intermittently formed at a high speed.

  Next, the resin coating is performed by thermal spraying a powder resin on the local area of the preheated object with the above coating apparatus. In the spraying of the powder resin by the above apparatus, the powder resin is supplied into the tank 1 in the state of FIG. 1A, and in this state, the volume of the measuring chamber is placed in the measuring chamber 21 of the quantitative cutout shutter device 2. The powder resin is automatically filled. Next, when the rotating body 20 is rotated by 180 °, the measuring chamber 21 is reversed to face the introduction flow path 31 of the thermal spray nozzle 3, and at the same time, the valve 25 is opened and the pressurized air is reversed into the measuring chamber. A fixed amount of the resin powder in the measurement chamber is blown through the supply port 24 and joins with the heated gas flowing through the spray flow path of the spray nozzle, and sprayed onto the extreme region of the object. Thus, according to the present embodiment, by repeating the above operation and spraying a small amount of powder resin, for example, intermittently multiple times on the same location in a state where the object is stopped, A predetermined amount of resin can be reliably formed even in a very narrow range. According to the method of the present invention, since a small amount of resin is intermittently injected, the sprayed resin is partially melted and can be melted and fused on the surface of the object, resulting in poor fusion. There is nothing. Moreover, the surface can be made smoother by reheating the formed resin pile.

  If the resin powder has a small particle size and the resin powder has poor sliding properties, the powder resin provided in the tank as shown in FIG. 2 (b) so that the resin is completely filled in the measuring chamber. The nozzle 13 of the supply device is extended to the uppermost part of the measuring chamber so as to compress and fill the powder.

Example 1: (Resin pile on laminated base paper)
As shown in FIG. 4, powder resin was sprayed on the front side of the prototype laminate base paper 70 ([front] polyethylene 18 μm / base paper (300 g / m ² ) / [back] polyethylene 18 μm) under the following conditions using the above apparatus.
Powder resin: Low-density polyethylene powder having an average particle size of 120 μm Single powder injection amount: about 20 mg
Distance between thermal spray nozzle and target surface: 6mm
Nozzle outlet hot air temperature: 320 ° C
Preheating: Delay before injection 1.5s
As a result, a resin pile 71 having a central coating thickness of 1.1 mm as shown in FIG. 4 could be satisfactorily formed without causing a stringing phenomenon.

Example 2 : (resin pile on the stepped portion)
A paper cup 50 as shown in FIG. 3 is formed by concatenating and forming both ends of a fan-shaped blank serving as the body 51 in a conical shape, curling the upper end thereof to form an open end, and lower end. The folded portion 52 is folded inward to form a folded piece 52, and an annular leg portion 58 of a bottom plate 57 drawn into a U-shaped cross section is crimped therebetween (FIG. 3C). As shown in an enlarged view in FIG. 3 (b), a step 54 is formed by superimposing both ends of the blank. In addition, an overlapping portion 55 is formed in the body portion, and paper edges are exposed at both ends of the overlapping portion inside and outside the cup.
When such a paper cup is filled with the contents and sealed, a sealing lid is heat sealed on the upper surface of the curled portion. In addition, when the product is consumed immediately after being filled in a store or the like, it is sold with an overcap fitted. When the sealing lid material is heat-sealed and sealed, the curled portion is usually crushed flat to increase the bonding area in a flange shape in order to prevent thermal adhesion failure of the lid material. Such a paper cup container is used as a container for direct drinking, but if there is a stepped portion at the opening end as described above, the mouth feels uncomfortable, especially those that are flattened into a flange shape. Is big.
In addition, when the overcap is fitted and engaged, a gap is formed between the curl stepped portion, which causes leakage. In order to eliminate such drawbacks, in this embodiment, a resin heap is formed on the step portion of the curl portion of the paper cup so as to eliminate the step and eliminate the leakage from the step. Since the stepped portion of the cup curl portion has a very small area, it is difficult to accurately deposit a small amount of resin on the paper cup production line, but in this embodiment, the post-processing is shown in FIG. It was made easier by the method. Post-processing is performed by, for example, preheating by blowing hot air with a preheating nozzle at a preheating station in the vicinity of the stepped portion of the opening curl portion of the paper cup that is intermittently conveyed by the conveyor in the paper cup production line, and then the resin spraying station In this example, the effect was confirmed by thermal spraying the powder resin as follows.

The opening curled portion 53 of the paper cup 50 was cut, and the powder resin was sprayed by the above apparatus near the stepped portion 54 of the cut curled portion 53 under the following conditions.
Powder resin: Low-density polyethylene powder having an average particle size of 120 μm Single powder injection amount: about 25 mg
Distance between spray nozzle and spray target surface: 10mm
Nozzle outlet hot air temperature: 320 ° C
Preheating: Delay before injection 1.5s
Remarks: Reheating with a hot air generator As a result, as shown in FIG. 6, a resin pile 59 having a coating film thickness of 0.3 mm can be satisfactorily formed without causing a stringing phenomenon so as to cover the stepped portion. did it.
In this way, by placing the resin on the stepped portion, the resin melts when the lid material is heat-sealed, so that the weldability with the lid material is increased without crushing the curled portion, and the sealing performance is improved. The feeling of incongruity when drinking directly could be eliminated. Also, in the case of an overcap, the step portion of the curled portion is eliminated, so that leakage from the curled portion can be prevented.

Example 3 : (Resin coating for the purpose of local modification of an object)
When the contents are filled in a paper cup and heated in a microwave oven, the dielectric constant of the paper is large, and in particular, electric field concentration occurs on the inner peripheral surface of the bottom (thread bottom) folded piece where the thickness increases, which causes burns. There are things to do. In this embodiment, in order to prevent the occurrence of scorching, thermal spraying is performed by mixing polyethylene resin powder with calcium carbonate powder as a low dielectric constant material on the exposed peripheral surface of the folded piece 52 of the cylindrical leg portion of the paper cup as shown in FIG. Then, the sprayed surface was modified so as not to burn.
Therefore, according to the present example, it was possible to prevent the occurrence of scorching due to microwave heating by a simple process without using a double container as shown in, for example, Japanese Patent Application Laid-Open No. 2004-161322.
As mentioned above, although embodiment and the Example of this invention were described, this invention is not restricted to these, It can apply widely to the intermittent injection of the small amount resin to the local area | region of a target object at high speed. For example, in the case of the paper container, in Example 1, the resin coating is applied to the stepped surface of the curl portion of the paper cup, but the resin is deposited over the entire circumference of the open curl portion of the paper cup or the open flange portion. Can do. Thereby, for example, in the case of a drawn paper container, wrinkles are generated in the flange portion and the sealing performance of the sealing material is lacking, but the heat sealing performance of the lid material is improved by placing resin on the entire flange portion. Can do. Further, by locally depositing the resin at the upper and lower ends where the blanking portion is subjected to curling or bending, pinhole generation during paper cup molding can be effectively prevented.

  INDUSTRIAL APPLICABILITY The present invention is suitable for spraying a coating material mainly composed of a synthetic resin on a particularly narrow local region of an object, and the object is a paper material (a laminated composite such as a resin laminate mainly composed of a paper layer). The present invention is widely applicable to high-speed intermittent injection of a small amount of resin to a local region of an object made of various materials such as a synthetic resin material and a metal material. In addition, since no flame is used, there is little thermal influence on the object and the industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 Tank 2 Fixed quantity cutting-out apparatus 3 Thermal spray nozzle 4 Preheating nozzle 11 Lower end opening part 12 Powder supply apparatus 13 Nozzle 20 Rotating body 21 Measuring chamber 22 Channel 23 Supply line 24 Gas supply port 25 Electromagnetic valve 31 Introductory path 32 Injection Flow path 33 Hot air generator 50 Paper cup 51 Trunk part 52 Folding piece 53 Opening curl part 54 Step part 55 Superposition part 57 Bottom plate 58 Annular leg part 59 Resin pile 60 Inorganic mixed resin layer 70 Prototype laminate base paper 71 Resin pile

Claims (7)

A coating method for coating a local region of a paper container with a coating material mainly composed of a synthetic resin, wherein the local region is preheated by blowing hot air on the local region to be coated with a resin of the paper container. Then, the powder mainly composed of synthetic resin is cut out in a fixed amount and pumped by a pressurized gas, joined to a heated gas that is hot air, and the powder mainly composed of synthetic resin is heated in the vicinity of the melting point and partially melted. A coating method characterized by intermittently spraying the local area. The coating method according to claim 1 , wherein the thermal spraying is a resin pile on a bonding step portion of an opening curl portion of the paper container having an opening. The spraying method for coating according to any one of claims 1-2 is a resin-coated exposed sheet edge of the paper containers. The coating method according to claim 1 , wherein the thermal spraying is a resin pile for the purpose of improving the rigidity of the paper container . The thermal spraying is a resin coating that locally reforms a powder obtained by mixing a modified substance intended for local modification of the paper container with the synthetic resin powder to modify the local area. 5. The coating method according to any one of 4 above. A coating apparatus for spraying powder mainly composed of synthetic resin on a local area of a paper container to cover the local area, a tank to which the powder is supplied, a thermal spray nozzle communicating with a lower end of the tank, A quantitative cutout shutter device provided between a lower end opening of the tank and the spray nozzle , and a preheating means ,
Preheat the local region of the paper container with the preheating means,
Cut out a fixed amount of powder from the tank with the fixed amount cutout shutter device ,
As a heating means, air is heated to a heated gas that is heated air, and the powder is heated in the vicinity of the melting point to be partially melted and intermittently sprayed from the spray nozzle to the preheated local region. The coating apparatus characterized by comprising. The quantitative cut-out shutter device comprises a rotating body that traverses the outlet opening of the tank. The rotating body is provided with a measuring chamber facing the outlet opening of the tank, and communicates with a gas supply port of the measuring chamber. A valve for supplying pressurized gas to the metering chamber, the rotating body being capable of intermittent rotation between the metering position and the spraying position, facing the outlet opening of the tank at the metering position; 7. The method according to claim 6 , wherein a predetermined amount of powder is measured, the measuring chamber faces the spray nozzle at an injection position, and pressurized gas is supplied from the valve to the measuring chamber to pressure-feed the powder to the spray nozzle. The coating apparatus as described.