JP5682915B2 - Manufacturing method, manufacturing apparatus and packaging bag for packaging bag material - Google Patents

Description

  The present invention relates to a method for manufacturing a packaging bag material, a manufacturing apparatus, and a packaging bag.

  The packaging bag is formed of a thermoplastic resin film such as polyolefin, but since many of these resins are hydrophobic, it is difficult to print on the surface well. Therefore, conventionally, in order to improve printability, surface treatment of a thermoplastic resin film by corona discharge or the like has been performed (see, for example, Patent Document 1).

JP 2000-296666 A

  However, the conventional surface treatment imparts excellent printing characteristics to the treated surface, but it is difficult to carry out a stable and uniform surface treatment because a uniform discharge cannot be generated on the entire plastic surface. There is a problem that.

  On the other hand, the present inventors have discovered that printing properties and fusing properties can be adjusted as desired by performing surface treatment via active oxygen generated by ultraviolet irradiation, and a thermoplastic resin in an atmosphere containing oxygen. A patent application has been filed for a method for producing a packaging bag material by placing a film and irradiating ultraviolet rays to oxygen (Japanese Patent Application No. 2010-058694, which is not known). However, this method has room for improvement in terms of the length of time, the flow of the entire manufacturing process of the thermoplastic resin film, the ease of designing the processing apparatus, and the like.

  The present invention has been made in view of the above circumstances, and a packaging bag material manufacturing method, a manufacturing apparatus, and a packaging bag capable of easily and simply manufacturing a packaging bag material having excellent printing characteristics stably and uniformly. The purpose is to provide.

  The present inventors have found that a packaging bag material having excellent printing characteristics can be produced in a short time in a stable manner by disposing at least one surface of a thermoplastic resin film in an atmosphere of atmospheric pressure plasma. It came to complete.

(1) A method for producing a packaging bag material,
A production method comprising a step of performing a surface treatment by disposing at least one surface of a thermoplastic resin film in an atmosphere of atmospheric pressure plasma.

  (2) The production method according to (1), wherein the time for disposing at least one surface of the thermoplastic resin film in an atmosphere of atmospheric pressure plasma is less than 4 seconds.

  (3) The manufacturing method according to (1) or (2), wherein an applied voltage for forming an atmosphere of atmospheric pressure plasma is less than 9 kV when a 50 Hz power source is used.

  (4) The method according to any one of (1) to (3), wherein a distance between one of the electrodes and at least one surface of the thermoplastic resin film is 0.5 mm or more and 10 mm or less.

  (5) The manufacturing method according to any one of (1) to (4), further including a step of printing on the surface-treated surface.

  (6) The manufacturing method according to any one of (1) to (5), wherein the thermoplastic resin is a polyolefin resin.

(7) A device for manufacturing a packaging bag material,
Atmospheric pressure plasma forming means for forming atmospheric pressure plasma in a space where at least one surface of the thermoplastic resin film is exposed;
A conveying means for moving the thermoplastic resin film relative to the space.

  (8) A packaging bag formed from the packaging bag material produced by the production method according to any one of (1) to (6).

  (9) The packaging bag according to (8), wherein the surface-treated surface is located outside.

  (10) The packaging bag according to (8) or (9), further comprising a printed layer positioned on the surface-treated surface.

  (11) The packaging bag according to any one of (8) to (10), wherein the surface-treated portions are fused together.

  According to the present invention, unlike the corona discharge in which the surface of the resin film is modified by discharge from an electrode that does not occur on all surfaces, the entire surface exposed to the atmosphere of atmospheric pressure plasma is modified. Is done. For this reason, printing characteristics can be imparted stably and uniformly in a short time.

  Hereinafter, although embodiment of this invention is described, this embodiment does not limit this invention.

  The packaging bag material manufacturing apparatus according to the present invention includes atmospheric pressure plasma forming means and conveying means.

  The atmospheric pressure plasma forming means includes a pair of electrodes arranged opposite to each other and an insulating sheet (for example, an acrylic sheet) covering the one electrode, and a gas source between the pair of electrodes. Argon gas and oxygen gas are supplied. When a voltage is applied to the electrodes in this state, atmospheric pressure plasma is generated in the space between the electrodes. By disposing at least one surface of the thermoplastic resin film in an atmosphere of atmospheric pressure plasma, the surface treatment of the surface can be performed. The configuration of the atmospheric pressure plasma forming means itself is well known in the art and will not be described in detail.

  The atmospheric pressure plasma forming means in the present embodiment may have a casing surrounding a pair of electrodes, thereby suppressing the diffusion of atmospheric pressure plasma and efficiently accumulating atmospheric pressure plasma in the space. it can. In addition, the housing is advantageous in that it surrounds the electrode and can further improve the safety of the surroundings.

  The distance from the electrode to the thermoplastic resin film naturally affects the distance between the electrodes, and when the distance between the electrodes increases, arcing (discharge phenomenon) occurs, and the energy received by the thermoplastic resin film increases and is strong. Exposed to treatment. For this reason, when a strong process is required, the thermoplastic resin film may be separated from the electrode up to a distance where signs of arcing can be seen. For example, the polypropylene film may be separated from the electrode by 5 mm or more. This distance (shortest distance) may be appropriately selected depending on the voltage applied to the electrode, but may generally be about 0.5 mm to 10 mm.

  The conveying means moves the thermoplastic resin film relative to the space. By adjusting the movement, the time for which the thermoplastic resin film is exposed to the atmospheric pressure plasma can be appropriately set. In addition, a conveyance part may convey a thermoplastic resin film and may move an atmospheric pressure plasma formation means.

  If the time for disposing at least one surface of the thermoplastic resin film in the atmosphere of atmospheric pressure plasma is excessive, the fusing performance of the thermoplastic resin film is likely to deteriorate, and the printing characteristics are not sufficiently improved. For this reason, it is preferable that the said time is less than 20 second, More preferably, it is 15 seconds or less, 10 seconds or less, and 7.5 seconds or less. On the other hand, the lower limit of the time may be appropriately set according to the material of the thermoplastic resin film, the voltage applied to the electrode, etc. within a range where desired printing characteristics can be obtained. For example, 1 second, 2 seconds, or 3 seconds. It may be. In the present invention, the step of placing in the atmosphere of atmospheric pressure plasma is generally sufficient once, but an embodiment in which the step is performed a plurality of times is also included in the present invention.

  Since the surface treatment of the thermoplastic resin film is completed in such a short time, even if the space is not so large, the surface treatment should be sufficiently performed while passing the thermoplastic resin film through the space at a certain speed. Can do. For this reason, it is easy to synchronize the speed at which the thermoplastic resin film is generated from the raw material and carried into the space, and the speed at which the surface treatment is completed and the thermoplastic resin film is carried out from the space. Integrated production up to the bag material can be easily performed.

  The power source that supplies current to the electrodes may be either a DC power source or an AC power source. However, in the case of a DC power source, the discharge phenomenon continues after dielectric breakdown occurs, continuously generating atmospheric pressure plasma. AC power is preferred because it cannot. If the applied voltage for forming the atmosphere of atmospheric pressure plasma is excessive, the fusing performance of the thermoplastic resin film is likely to be lowered, and the printing characteristics are not sufficiently improved. For this reason, the applied voltage may be appropriately set in consideration of the magnitude of the AC pulse, but when a 50 Hz power source (for example, 100 V power source or 130 V power source) is used, it is preferably less than 9 kV. More preferably, it is 8.5 kV or less. On the other hand, the lower limit of the applied voltage is appropriately set depending on the material for the thermoplastic resin film, the time for placing at least one surface of the thermoplastic resin film in the atmosphere of atmospheric pressure plasma, etc. within a range where desired printing characteristics can be obtained. For example, when a 50 Hz power supply is used, it may be 5 kV, 6 kV, or 7 kV.

  Examples of the thermoplastic resin used in the present invention include ethylene resins such as high density polyethylene and low density polyethylene, polyolefin resins such as propylene resin, polymethyl-1-pentene, ethylene-cyclic olefin copolymer, nylon-6, Polyamide resins such as nylon-6,6, nylon-6,10, nylon-6,12, etc., thermoplastic polyester resins such as polyethylene terephthalate and copolymers thereof, polyethylene naphthalate, aliphatic polyester, polycarbonate, atactic One type or two or more types of thermoplastic resins such as polystyrene, syndiotactic polystyrene, polyphenylene sulfide and the like can be mentioned. Among these, a non-polar polyolefin resin is preferable in that the present invention is more useful, and more specifically an ethylene resin.

  The manufacturing method of the present invention may further include a step of printing on the surface-treated surface. Since the surface surface-treated as described above has excellent printing characteristics, a strong printing layer can be formed. The printing method is not particularly limited, and may be gravure printing or the like.

  This invention includes the packaging bag formed from the above-mentioned packaging bag material. The packaging bag is generally formed by partially fusing a packaging bag material. Since deterioration of the fusing property of the surface-treated surfaces is suppressed, the portion to be fused is between the surface-treated surfaces, between the non-surface-treated surfaces, or the surface-treated surface. The surface may be any surface that is not surface-treated, and may be appropriately selected according to the shape of the bag (how to fold the packaging bag material) and the use of the fused portion.

  The part fused with the surface-treated parts may block a non-opening opening that is not generally opened like the bottom of the bag, or is generally opened like the top side of the bag. The opening for opening may be closed. In the former case, the surface-treated parts are desirably joined with a strong fusing force, and in the latter case, the surface-treated parts are desirably joined with an appropriate fusing force.

  Since the printing layer is usually formed on the outside, it is preferable that the surface-treated surface having excellent printing characteristics is located on the outside, but it may be located on the inside. The printed layer is preferably formed on the surface-treated surface, but may be on the surface that has not been surface-treated. In addition, formation of a printing layer may be performed in the manufacturing process of the material for packaging bags as mentioned above, and may be performed with respect to a packaging bag.

  As a plasma generation means, a 100 V, 50 Hz atmospheric pressure plasma generation apparatus “KIP-101” (manufactured by Keitec Research Co., Ltd.) is used, and the electrodes arranged facing each other vertically have a length of 20 mm with respect to the conveyance direction of the thermoplastic resin film An acrylic sheet (thickness 0.5 mm) as an insulator was laid on the upper surface of the lower electrode.

<Example 1>
A low density polyethylene film was used as the thermoplastic resin film. In the atmospheric pressure plasma, argon gas is supplied as a discharge gas at a flow rate of 10 liters / minute, oxygen gas is supplied as a process gas at a flow rate of 0.3 liters / minute, and a voltage of 8 kV is applied to the electrodes. It was performed by applying. At this time, the distance from the upper electrode for generating plasma to the low density polyethylene film was set to 3.5 mm. Under such conditions, a low-density polyethylene film was conveyed at a speed of passing through the space between the electrodes in 1 second to produce a packaging bag material.

<Example 2>
Using a high density polyethylene film as the thermoplastic resin film, the distance from the electrode of the top to a high density polyethylene film except that a 2.0 mm, to produce a packaging bag material by the same procedure as in Example 1.

<Reference Example 3>
A packaging bag material was produced in the same procedure as in Example 1 except that the voltage applied to the electrode was 9 kV and the distance from the upper electrode to the low density polyethylene film was 2.0 mm.

< Reference Example 4>
A packaging bag material was produced in the same procedure as in Reference Example 3 except that the low density polyethylene film was conveyed at a speed of passing through the space between the electrodes in 4 seconds.

< Reference Example 5>
A packaging bag material was produced in the same procedure as in Example 2 except that the voltage applied to the electrode was 9 kV.

<Reference Example 6>
In velocity through the space between the electrodes at 4 seconds, except that conveys the high-density polyethylene film was prepared packaging bag material in the same manner as in Example 2.

(Comparative Example 1)
A high-density polyethylene film was used as the plastic film substrate, and corona discharge was performed with a discharge wattage of 400 W and a discharge wire length of 300 mm. A plastic film was placed at a distance of 1 mm from the electrode, and surface treatment was performed at a plastic film feed rate of 33 m / min to produce a packaging bag material.

(Comparative Example 2)
A packaging bag material was produced in the same procedure as in Comparative Example 1 except that a low-density polyethylene film was used as the plastic film substrate and the discharge wattage was 300 W.

(Comparative Example 3)
“SUV110GS-36” (manufactured by Sen Special Light Source Co., Ltd.) was used as the light source. In order to stabilize the output of the light source, preliminary irradiation was performed for about 30 minutes to 1 hour, and then the plastic film was subjected to surface treatment. The treatment length is 100 mm, and the treatment time taken to surface-treat 100 mm is described below.

  A high-density polyethylene film was used as the thermoplastic resin film, and ultraviolet rays having wavelengths of 185 nm and 254 nm were irradiated for 60 seconds toward the film at a position 3 cm away from the light source to produce a packaging bag material.

(Comparative Example 4)
A low-density polyethylene film was used as the thermoplastic resin film, and 13 seconds of irradiation, 13 seconds of non-irradiation (light source off), 13 seconds of irradiation, 13 seconds of non-irradiation, and 13 seconds of irradiation were sequentially performed. Except for the above, a packaging bag material was produced in the same procedure as in Comparative Example 3.

(Comparative Example 5)
Except for 10 seconds irradiation, 10 seconds non-irradiation (light source off), 10 seconds irradiation, 10 seconds non-irradiation, 10 seconds irradiation, 10 seconds non-irradiation, 10 seconds irradiation A packaging bag material was produced in the same procedure as in Comparative Example 4.

[Evaluation]
A printing layer of a polyamide resin gravure ink was formed on the packaging bag material produced in the examples and comparative examples by a gravure printing machine. The printed layer was rubbed back and forth 1000 times while applying an excess weight of 457 g by “Kimwipe”, and the subsequent state was evaluated according to the following criteria. The results are shown in Table 1.
◎: No damage was confirmed on the printed layer. ○: Scratch was confirmed on the printed layer. △: The printed layer was slightly peeled. ×: The printed layer was severely peeled.

Of the packaging bag materials produced in the examples and comparative examples, in order to test the uniformity of treatment on the surface-treated surface, the treated samples of each example and comparative example were formed into a square having a length of 10 cm and a width of 10 cm. Cut out and measured the contact angle of 9 points per sample using the contact angle measuring device, and evaluated the variation state according to the following criteria. The results are shown in Table 1.
◎: There was almost no variation between the average value of the contact angle at 9 points and each measured value, and the treatment was uniform. ○: There was some variation between the average value of the contact angle at 9 points and each measured value. Although it was observed, the treatment was almost uniform. ×: More than half of the average values of the contact angles at 9 points and each measured value were uneven, and the treatment was uneven.

Of the packaging bag materials produced in the examples and comparative examples, the surface-treated surfaces were bonded together at 200 ° C. for 1 second and heat-sealed. The fused portions were pulled with the same force in the direction of separating from each other, and the state at that time was evaluated according to the following criteria. The results are shown in Table 1.
◎: There was no change in the fused part, and the film was broken. ○: The fused part was peeled off and the film was broken. △: The fused part was peeled before the film was stretched and broken. Peeled

As shown in Table 1, the printing characteristics were unsatisfactory in the untreated product, and the fusing property was poor in Comparative Examples 1 and 2, whereas good printing performance was obtained in the examples. Further, in Comparative Examples 3 to 5, the surface treatment took 40 seconds or more, whereas in the Examples, only a short time of about 5 to 20 seconds was required. Thereby, it was confirmed that the packaging bag material which is excellent in a printing characteristic can be easily manufactured by performing the surface treatment via plasma. This is because corona discharge gives excessive energy to the film and destroys molecules, while atmospheric pressure plasma has low energy given to the film and damage to the molecules is small. On the other hand, it is assumed that the energy applied to the film is larger than that of ultraviolet irradiation, and the time required for the surface treatment can be shortened by adjusting the applied voltage, the distance from the electrode to the film, and the treatment time. In addition, although it cannot distinguish in the evaluation result, compared with Comparative Examples 3-5, the direction of the Example has improved the adhesiveness of the ink after printing more.

By comparing Example 1 and Reference Example 3, Example 2 and Reference Example 5, the application voltage to the electrode is less than 9 kV when a power supply of 100 V and 50 Hz is used, thereby maintaining the fusion property. It was found that it is preferable from the viewpoint of. Further, by comparing Reference Examples 3 and 4, Example 2 and Reference Example 6, it is possible that the time for disposing at least one surface of the thermoplastic resin film in the atmosphere of atmospheric pressure plasma is less than 20 seconds. It has also been found that it is preferable from the viewpoint of maintaining the properties and maximizing the printing performance.

Claims (7)

A method for producing a packaging bag material comprising:
Placing at least one surface of the thermoplastic resin film in an atmosphere of atmospheric pressure plasma formed by a dielectric barrier discharge method at an applied voltage of less than 4 seconds and less than 9 kV, and performing the surface treatment; and The manufacturing method which has the process of printing on the done surface. One electrode, a distance between the at least one surface of the thermoplastic resin film, a manufacturing method of claim 1 wherein in 0.5mm or 10mm or less. The manufacturing method according to claim 1, wherein the thermoplastic resin is a polyolefin resin. An apparatus for manufacturing packaging bag materials,
Atmospheric pressure plasma forming means for forming atmospheric pressure plasma by a dielectric barrier discharge method at an applied voltage of less than 9 kV in a space between electrodes where at least one surface of the thermoplastic resin film is exposed;
A conveying means for moving the thermoplastic resin film relative to the space and passing the space in which the atmospheric pressure plasma is formed in less than 4 seconds;
And a printing unit that performs printing on the surface of the resin film that has been surface-treated with the atmospheric pressure plasma. The packaging bag formed from the packaging bag material manufactured with the manufacturing method in any one of Claim 1 or 3. The packaging bag according to claim 5, wherein the surface-treated surface is located outside the packaging bag. The packaging bag according to claim 5 or 6, wherein the surface-treated portions are fused together.