JPH08171239A - Method and device for printing plastic container - Google Patents

Abstract

PURPOSE: To perform many kinds of printing with a small amount and with high productivity on a plastic container having a body part which is soft, easily recessed, and whose wall parts are brought into easily close-contact each other. CONSTITUTION: The plastic container 1 whose body part 1b is easily recessed is placed on a pushing-up tool having a pushing-up surface 16 and provided on a intermittently rotating printing turret 4 at standstill time when the pushing-up tool is in a lowering condition. Both ends 1a and 1c of the container 1 are held, the pushing-up tool 25 rises as soon as the pushing-up tool revolves, both wall parts of the body part 1b of the container are brought into close- contact, and toner is transferred to the surface of the close-contact part in the form of powder figure under a bias voltage of a power source 56 by the photoreceptor drum 61 of an electrophotographic unit 60 while the pushing-up tool revolves. Then, the toner is fixed by the irradiation of an exposing lamp 67 on the powder figure. The surface tension of the body part 1b is desirably >=36dyn/cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic bag which is suitable for storing medical products such as infusions, foods such as mayonnaise and ketchup, cosmetics, etc. The present invention relates to a printing method and apparatus for plastic containers such as.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 4-163124 and Japanese Unexamined Patent Publication (Kokai) No. 4-163125 disclose a surface of an upper portion of a close-together body part by closely contacting opposing walls of a plastic bag having a flat body part. There is disclosed a method of transfer roll printing, silk printing or offset printing. The disclosed method has a problem that the printing speed is slow and productivity is low because it is a manual method. Further, since the printing method is transfer roll printing, silk printing or offset printing, it takes time and cost to produce a printing plate, and thus there is a problem that it is not suitable for high-mix, low-volume printing.

[0003]

SUMMARY OF THE INVENTION The present invention provides a body portion that is capable of printing with high productivity, is suitable for high-mix, low-volume printing, and is soft and easily dented, and the opposing wall portions are easily in contact with each other. An object of the present invention is to provide a printing method and device for printing a plastic container such as a plastic bag.

[0004]

According to a first aspect of the present invention, there is provided a method of printing a plastic container according to claim 1, which is a method of printing a blow-molded plastic container in which a body portion is easily dented, the method being provided on an intermittently rotating printing turret. The container is placed on a push-up tool having a push-up surface having a shape of a part of a cylindrical surface which is a revolving locus surface when the push-up tool is in a lowered state during a stop period, and the container is in a raised state. Both ends of the container are grasped, and as soon as the push-up tool revolves, the push-up tool is immediately raised to bring the two opposite wall portions of the body of the container into close contact with each other. By the method, the toner is transferred in the form of a powder image under a bias voltage applied to the push-up tool, and then the powder image is exposed to fix the toner.

The surface tension of the surface of the body of the plastic container to be printed is 36 dyn / cm or more, and the plastic constituting the container does not substantially absorb in the near infrared region. Contains a fixing resin and a colorant, and has a near-infrared absorbing property,
The exposure of the powder image is preferably performed by flash exposure with near infrared rays (claim 2).

A plastic container printing device according to a third aspect is a blow-molded plastic container printing device in which a body portion is easily dented, and the device has a holding device for the container; A plurality of push-up tools are provided at equal intervals in the circumferential direction, rotate intermittently, and are provided with a transfer station, a transfer station, and a fixing station in this order along the rotation direction, and the push-up surface is a cylindrical surface that is a revolution trajectory surface when it is in an ascending state. A printing turret in the form of a part of a container; a device for placing the body of the container gripped by the container gripping device on a push-up tool in a lowered state during a period when the printing turret is stopped at the transfer station; Device for holding both ends of the container placed on the push surface during the period; Device for separating the container holding device from the container during the stop period; Rotation of the printing turret Immediately after that, a device for raising the push-up tool to bring the two opposite wall parts of the body of the container into close contact with each other; a toner image printed on the body of the revolving body disposed so as to be able to contact the body of the transfer station. A photosensitive drum of an electrophotographic unit for transferring in the form of a powder image; a direct current power source for applying a bias voltage to the push-up tool, and a device for thermally fixing the powder image provided in the fixing station. .

The plastic container gripping device according to claim 3 is arranged at equal intervals in a plurality of circumferential directions on the transfer turret that rotates intermittently and stops at the same time as the printing turret at the transfer station. It is preferable to include a vacuum suction cup for holding the vacuum suction cup, and a device for advancing the vacuum suction cup during gripping and retracting the vacuum cup when separating from the container (claim 4).

[0008]

According to the first aspect of the present invention, the blow-molded plastic container, on which the body is easily dented, is placed on the push-up tool provided on the intermittently rotating printing turret during the stop period when the push-up tool is in the lowered state. The container is placed and grips both ends of the container, and immediately after the pusher revolves, the pusher is lifted to bring the two opposite wall portions of the body of the container into close contact with each other. It can be done automatically using the device numbered 0006. Therefore, productivity is high. While revolving the push-up tool, the toner is transferred in the form of powder image under the bias voltage applied to the push-up tool on the surface of the close contact part of the body by electrophotography, and then the powder image is exposed to expose the toner. Since it is fixed, no printing plate is required. When printing a new image, it is only necessary to switch the image data on the computer memory to the new image data, and the troublesome printing plate changing work as in the past is unnecessary. Therefore, many kinds,
Suitable for small quantity printing. Since the push-up surface of the push-up tool has a shape of a part of the cylindrical surface which is the orbital trajectory surface when the push-up tool is in the ascending state, the surface of the body part that is closely attached to the push-up surface is also the cylinder in the ascending state. It has a shape of a part of a cylindrical surface which is a revolution locus surface of the surface of the part. Therefore, at the time of transfer, the cylindrical photosensitive drum is brought into smooth contact with the entire surface of the intimate contact of the body portion, and transfer leakage does not occur. Since there is no gap between the two walls of the body that are in close contact with each other, the electric field is uniformly applied through the push-up tool, so that transfer leakage does not occur from this point as well.

In the invention according to claim 2, the surface tension of the surface to be printed of the body of the plastic container is 36 dy.
It is n / cm or more. As the experimental example described in paragraph 0031 shows, if the surface tension is lower than 36 dyn / cm, even if the toner melts and coalesces due to heating, it is difficult for the toner to flow to minute recesses on the plastic surface. However, the adhesive force to the plastic surface is reduced, and the printed image is easily peeled off by the action of a slight frictional force. However, when the surface tension is 36 dyn / cm or more, peeling of the printed image is unlikely to occur. The powder image is exposed by near-infrared flash exposure for an extremely short time, and the plastic forming the container does not substantially absorb in the near-infrared region. There is no risk of damage. Since the toner contains a fixing resin and a colorant and has a property of absorbing near infrared rays, the toner is melted and fixed in a short time of flash exposure (for example, about 1 msec.). Therefore, printing is performed with high productivity.

The device of the invention according to claim 3 is a printing device for a blow-molded plastic container, in which the body portion is easily dented, and the device is a gripping device for the container; Equipped with push-up tools at equal intervals in the circumferential direction, rotating intermittently, and provided with a transfer station, a transfer station, and a fixing station in this order along the rotational direction, and the push-up surface is a part of the cylindrical surface that is the revolution trajectory surface when it is in a raised state. A printing turret in the form of a device; a device for placing the body of the container gripped by the container gripping device on a push-up tool in a lowered state during the period when the printing turret stops at the transfer station; Device for holding both ends of the container placed on the push surface; Device for separating the container gripping device from the container during the stop period; Pushing up immediately when the printing turret rotates Since it is equipped with a device for ascending and bringing the opposite wall parts of the body of the container into close contact with each other, it is possible to automatically bring the opposite wall parts of the container body above the pushing surface of the push-up tool into close contact with each other. You can Therefore, productivity is high. A photosensitive drum of an electrophotographic unit, which is arranged in the transfer station so as to be contactable with the body and transfers a print image in the form of a toner powder image, a DC power supply for applying a bias voltage to the pushing tool, and Since it is equipped with a device for thermally fixing the powder image disposed in the fixing station, it does not require a printing plate, and is suitable for printing a wide variety of products in small quantities. Since the push-up surface of the push-up tool has a shape of a part of the cylindrical surface which is the orbital trajectory surface when the push-up tool is in the ascending state, the surface of the body part that is closely attached to the push-up surface is also the cylinder in the ascending state. It has a shape of a part of a cylindrical surface which is a revolution locus surface of the surface of the part. Therefore, at the time of transfer, the cylindrical photosensitive drum is smoothly brought into contact with the entire surface of the body portion that is in close contact, and transfer leakage does not occur.

According to a fourth aspect of the present invention, the plastic container gripping device according to the third aspect is arranged at equal intervals in the circumferential direction on the transfer turret that rotates intermittently and stops at the same time as the printing turret at the transfer station. The gripping device is provided with a vacuum suction cup for gripping the container, and is provided with a device for advancing the vacuum suction cup when gripping and retracting the vacuum cup when separating from the container. , The plastic container is automatically placed on the push-up tool of the printing turret, and after being placed, the gripping device can be automatically separated from the plastic container. Therefore, productivity is high.

[0012]

1 and 2 show an infusion solution storage bag 1 which is an example of a plastic container printed by the method of the present invention. The bag 1 is formed by blow molding from a parison (not shown) made of soft low density polyethylene, and has a mouth portion 1a, a body portion 1b and a hanging portion 1c.
It has. The mouth portion 1a is relatively thick and difficult to bend. The body 1b is flat, and most of the body is relatively thin except for the slightly thick upper end (mouth 1a side) and lower end (suspension 1c side).
Easy to bend or dent. Reference numeral 1a1 is a flange portion, and 1c1 is a hole for inserting a hanger. A printing unit 6 prints a print image 8 such as a product name, content type, weight, manufacturer, manufacturing date, and pattern. Before being sent to a delivery chute 2 described later, air is evacuated from the mouth portion 1a, and both walls of the body portion 1b are close to each other, and the body portion 1b is substantially flat.

FIG. 3 shows a bag printing apparatus 100 according to an embodiment of the present invention. The printing apparatus 100 includes an input chute 2, a transfer turret 3, a printing turret 4, and a delivery conveyor 5. The delivery chute 2 is inclined steeply and obliquely downward and rightward as a whole so that the bag 1 can naturally fall due to gravity. In the case of this embodiment,
The inclination angle θ is about 70 degrees, and the inclination angle θ is preferably 45 degrees or more. Inlet chute 2 is upper chute 1
0, 1 pair of corona treated rolls 11 and lower chute 1
2 is provided. The chutes 10 and 12 have a gap width slightly larger than the outer diameter of the mouth portion 1a of the bag 1,
Two parallel guide rods 10a, 1 that guide each other
2a, and has a gap width slightly larger than the thickness of the suspending portion 1c, and comprises two opposing parallel guide rods (not shown) that guide the suspending portion 1c. Upper shoot 1
0 and the lower chute 12, the upper part and the lower part of the corona-treated roll 11, and the lower chute 12, respectively.
The stoppers of the bag 1 are attached to the lower ends of the
a, 13b and 13c are provided. The stoppers 13a, 13b and 13c are the piston rods 1 of the fixed air cylinders 14a, 14b and 14c, respectively.
It is fixed to the tips of 4a1, 14b1 and 14c1 and can reciprocate in the direction of the arrow to open and close the chutes 10, 12. The reciprocating motion of the piston rods 14a1, 14b1 and 14c1 is based on a signal from the proximity switch 36 disposed at a fixed position in the vicinity of the transfer turret 3, and the air cylinders 14a, 14b and 14c.
It is performed by opening and closing an electromagnetic valve (not shown) of the air guide tube that operates the.

The corona treatment roll 11 including the roll 11x and the roll 11y is provided to improve the surface tension of the printing portion 6 of the bag 1 by corona discharge treatment. The corona treatment roll 11 is adapted to be rotated at a predetermined speed during operation by a drive mechanism (not shown). The gap width between the roll 11x and the roll 11y is set to be equal to or slightly larger than the sum of the thicknesses of both wall portions of the body portion 1b. Each roll 11x, 11y
Has a soft rubber layer 11a (for example, a hardness of 60) adhered onto a metal (for example, steel) pipe 11b whose both ends are closed.
And a height h of at least the printing portion 6 (see FIG. 1) of the body portion 1b of the bag 1 made of a silicon rubber layer having a thickness of 3 mm).
The roll 11x on the right side of the drawing has a width of
It is possible to contact the entire surface of. The soft rubber layer 11a is provided to ensure close contact between the roll 11 and the body portion 1b of the bag 1. On the roll 11x on the printing unit 6 side,
Shaft 11c fixed to both sides of the metal pipe 11b
High frequency power supply 15 for corona discharge treatment (for example, maximum 14 kV, 33 kHz) via a brush (not shown) that contacts a slip ring (not shown) provided on the
Connect to. The roll 11y is grounded via a similar brush (not shown). Power supply 15 is ON-OF
The F switch 15a is provided, and a sensor (not shown) senses a period during which the bag 1 passes the roll 11, and the switch 15a is turned on only while the bag 1 is passing. The corona discharge treatment is performed by output control (for example, 0.2 to 0.4 kw).

The lower end 12x of the lower chute 12 is a gripping station P in which the upper guide rod (12) is shortened by a length that is substantially close to the width of the bag 1.
A transfer turret 3 that intermittently rotates in the direction of arrow A is arranged near the upper surface side of the gripping station P, that is, on the right side in the drawing. The transfer turret 3 is provided with a plurality of (four in this embodiment) vacuum suction devices 17 at equal intervals in the circumferential direction, that is, around the central axis 18 every 90 degrees. The vacuum suction device 17 is attached near the four corners of the support plate 20, and is connected to a vacuum source (not shown) via a conduit (not shown) passing through the hole 18a of the central shaft 18 (4).
A vacuum cup 19 and an air cylinder 21 are provided. The air cylinder 21 is a side plate 22 of the turret 3.
It is fixed at a right angle to the center and is connected to a pressurized air source (not shown) through a conduit (not shown) passing through the hole 18a of the central shaft 18. Piston rod 21
A support plate 20 is fixed to the tip of a (see FIG. 4).

The transfer turret 3 includes an air cylinder 21.
The side plate 22 to which is fixed is the lower end 12x of the feeding chute 2.
When it reaches the gripping station P in parallel with
Immediately, the air cylinder 21 operates, the piston rod 21a that had been in the retracted position advances, and the vacuum cup 19 contacts the body 1b of the bag 1 that is stopped,
The body portion 1b is vacuum-sucked at four points and then rotated again, and then the piston rod 21a is retracted. The transfer turret 3 is further stopped when the side plate 22 reaches the transfer station Q located on the opposite side of the central axis 18 with respect to the gripping station P, and immediately the air cylinder 21 is operated and the piston rod 21a is advanced. , The suctioned body 1b of the bag 1 is placed on the push-up tool 25 of the printing turret 4 at the transfer station Q so that the height direction thereof is perpendicular to the revolution direction, and then the vacuum cup 19 is placed. The vacuum cup 19 is released, and the vacuum cup 19, that is, the piston rod 21a moves backward and then rotates (see FIG. 4). The piston rod 2
The forward / backward movement of 1a and the vacuum suction / release of the vacuum cup 19 are performed by a cam mechanism (not shown) provided on the central shaft 18 or the like, respectively, by an air conduit switching valve (not shown) and a vacuum conduit switching valve (not shown). Vacuum and air: (not shown)).

On the opposite side of the gripping station P with respect to the transfer turret 3, a central axis 23 having an axis in a virtual plane perpendicular to the lower end 12x and passing through the axis of the central axis 18.
And a printing turret 4 which is intermittently rotated in the direction of arrow B is disposed. The printing turret 4 includes a push-up device 24 having push-up tools 25, which is an integral multiple of the number of the air cylinders 21 of the transfer turret 3 (twice in this embodiment), and the central shaft 2 is provided.
3 are provided at equal intervals in the circumferential direction. The angular velocity of the printing turret 4 during rotation (for example, 2060 degrees / minute) is 1 / n of the angular velocity of the transfer turret 3, and both turrets 3 and 4 are rotated.
Are stopped at the same time (for example, 0.4 seconds), and the central portions of the vacuum suction device 17 and the push-up device 24 in the rotational direction reach the center of the transfer station Q (on the virtual plane) at the same time. ing.

Push-up device 2 located at transfer station Q
In FIG. 4 showing the state of No. 4, 25 is a push-up tool,
Upper layer 25a made of conductive rubber, intermediate layer 25b made of a conductor (usually metal such as aluminum, stainless steel, copper)
And electrical insulators (eg ceramic plates or Teflon plates)
It is composed of a lower layer 25c made of, and each layer is adhered by an adhesive (see FIG. 7). Note that the following description will be made assuming that the push-up device 24 is in the horizontal position (although actually, the push-up device 24 is inclined obliquely downward as shown in FIG. 3). The push-up tool 25 has a semi-cylindrical shape as a whole, and the main portion 25 excluding both end portions 25a2 facing diagonally downward of the upper layer 25a.
The push surface 16 which is the surface of a1 has a shape of a part of a cylindrical surface which is the revolution locus surface 7 (FIG. 3) in the push up (up) state. The length of the push surface 16 (horizontal length in FIG. 4) is slightly smaller than the height of the body portion 1b of the bag 1, and the width is set to be substantially equal to the width of the body portion 1b of the bag 1 (see FIG. 7). ). The intermediate layer 25b made of a conductor is provided with a conductive wire (not shown) connected to the slip ring 53 provided around the central axis 23 of the printing turret 4, a brush 54 contacting the slip ring 53, and a conductive wire 55 connected to the brush 54. Via a high voltage DC power supply 56 (eg +3 kV) for applying a bias voltage to the bag 1 (FIG. 3).

The push-up tool 25 is fixed on the support 26 with an adhesive. An air cylinder 28 fixed to the side plate 27 of the printing turret 4 via a perforated disc 27b.
Of the piston rod 28a is fixed to the lower surface of the support 26, and therefore the support 26, that is, the push-up tool 25.
Can be moved up and down with respect to the side plate 27 within a predetermined height range H (the distance between the upper surface of the flange portion 31a described later and the bottom surface 29a of the hollow column 29). As shown in FIG. 4, when the support body 26 is at the lowest position, two hollow support columns 29 containing the bushings 30 are fixed to the side plate 27 so as to come into contact with the lower peripheral edge projections 26a of the support body 26. Push-up tool 25
A guide rod 31 having a flange portion 31a serving as a stopper at the time of ascending and being fixed to the hole upper surface 26a1 of the lower peripheral edge projection 26a of the support 26 is inserted through the bushing 30. When the support body 26 rises due to the rise of the piston rod 28a, the guide rod 31 also rises at the same time, and the upper surface of the flange portion 31a has the concave portion 27 of the side plate 27.
a, contact the bottom surface 29a of the hollow column, and support the support 2
6, therefore the lifting of the push-up tool 25 stops.

The hanging portion 1 of the bag 1 placed on the push-up tool 25.
An L-shaped arm 32 is fixed to a side portion of the support body 26 on the c side. On the horizontal portion 32a of the arm 32, the suspension receiver 3
3 is fixed so that a slight gap is generated between the upper surface 33a and the hanging portion 1c (at the time of being placed). An L-shaped swing member 34 is pivotally attached to the upper portion of the forked vertical portion 32b of the arm 32. The upper portion 34a of the rocking member 34 has an upper body 34a to which a suspension portion retainer 34c is fixed,
The hanging portion retainer 34c and the horizontal portion 32a are pulled by the strong spring 35 in the state of FIG. Swing member 3
A pin 34d is fixed to an end of the lower body 34b of No. 4. The pin 34d is a retainer portion 38 of a dogleg-shaped swing retainer 38 pivotally attached to an upper portion of a column 37 fixed to the side plate 27.
It is pressed downward by a. Side plate 27
Piston rod 39 of air cylinder 39 fixed to
A swinging presser 38 is pivotally attached to the upper end of the connecting rod 40 pivotally attached to the upper end of the a. Therefore, the pin 34d is held by placing the piston rod 39a in the raised position.

The mouth portion 1 of the bag 1 placed on the push-up tool 25
A mouth receiver 43 having the same shape as the outer surface of the lower half portion of the mouth portion 1a is provided at a position where it comes into contact with a. The lower end of the mouth receiver 43 is a plate portion 43a (see FIGS. 6 and 8) having a small hole 43a1 extending in the direction perpendicular to the paper surface of FIG. 4 and fixed to the side plate 27 in the small hole 43a1. The upper small diameter portion 41a of the rod 41 is inserted. The spring 42 is provided between the plate portion 43 a and the lower end portion of the rod 41. The protruding portion 44 fixed to the side portion of the support body 26 and the protrusion 43b fixed to the side portion of the mouth portion receiving portion 43 engage with each other under the light pressure of the spring 42 to raise the height of the mouth portion receiving portion 43. Holds in a fixed direction. The L-shaped vertical portion 45a has a bifurcated arm 4 on a side portion of the mouth receiver 43 opposite to the push-up tool 25.
5 is fixed (see FIG. 8). A mouth retainer 47 is swingably pivotably attached to the upper end of the arm 45. On the upper part of the mouth retainer 47, a mouth retainer 47a whose inner surface is the same as the outer surface of the upper half of the mouth 1a is attached. A pin 47a is provided at the bottom of the mouth retainer 47, and the pin 47a is
It is pressed downward by a swing presser 48 corresponding to the swing presser 38. The mouth retainer 47 is pulled by the spring 46 with respect to the mouth receiver 43 in the state shown in FIG. Numerals 49, 50, 51 and 51a are columns, connecting rods, air cylinders and piston rods corresponding to the columns 37, connecting rod 40, air cylinder 39 and piston rod 39a, respectively. In addition, the air cylinders 28, 39, and 51 have the holes 2 of the central shaft 23.
It is connected to a source of pressurized air (not shown) via a conduit (not shown) running through 3a.

At the transfer station Q, the air cylinders 39 and 51 of the push-up device 24 operate and the piston rods 39a and 51a descend. As shown in FIG.
Along with this lowering, the pressing portions 38a and 48a ascend,
Separate from pins 34d and 47b, respectively. Immediately, the spring 35 contracts, and the hanging portion retainer 34c strongly presses and holds the hanging portion 1c against the upper surface 33a of the hanging portion receiver.
At the same time, the spring 46 is also contracted so that the mouth retainer 47a presses the upper half of the mouth 1a to lower it, and cooperates with the mouth receiver 43 to hold the mouth 1a. Immediately thereafter, when the vacuum of the vacuum cup 19 is released, the air cylinder 21 operates and the piston rod 21a rises, the transfer turret 3 rotates and the vacuum cup 19 moves to the bag 1 and the transfer station Q.
Move away from Immediately when the printing turret 4 rotates, the air cylinder 28 operates and the piston rod 28a rises in height H, and the bag 1 is pushed up by the push-up tool 25. At that time, the engagement between the protrusion 44 and the protrusion 43b is released,
The mouth portion 1 of the bag 1 in which the mouth portion 1a and the hanging portion 1c are held
a is the mouth retainer 47 due to the elastic resistance of the spring 42.
As a result of being pulled downward together with a and the mouth portion receiver 43, at least the upper and lower walls of the printing portion 6 of the body portion 1b come into close contact with each other without any slight gap as shown in FIG. If there is a gap, the electric field at that portion becomes low, which causes a defective print portion, which is not preferable. Shortly after the push-up device 24 passes below the fixing flash lamp 67 described later, the piston rod 28a descends (retracts) and the piston rods 39a and 51a rise (advance) to the position shown in FIG. It is configured to return. The piston rods 28a, 39a and 51a are raised and lowered, respectively, by a cam mechanism (not shown) provided on the central shaft 23 and the like, and a switching valve (not shown) of an air conduit connected to each air cylinder.
It is performed by opening and closing.

The electrophotographic unit 60 is arranged so that the photosensitive drum 61 is located in the section on the downstream side of the transfer station Q, that is, the upper portion of the printing turret 4 in FIG. The electrophotographic unit 60 is placed on the push-up tool 25 and surrounds the photosensitive drum 61 driven in the arrow direction at a peripheral velocity equal to the moving velocity of the upper surface of the bag 1 pushed up from below in the state of FIG. Printing turret 4
From the upstream side of the developing device 62, the laser exposure device 63,
A corona charger 64, a cleaner 65 (made of, for example, a brush) and a static eliminator 66 (made of, for example, a light emitting diode) are provided. The laser exposure device 63 includes a reflection mirror 63a and a polygon mirror 63b,
63c is a laser beam modulated by an image signal from an image memory stored in a memory of a computer (not shown).

Photosensitive layer 61a of the photosensitive drum 61 which is grounded
Is made of an organic photoconductor, selenium, amorphous silicon, or the like. The developing device 62 includes a fixing resin powder, a coloring agent,
A toner such as a charge control agent and a carrier such as ferrite powder are stored. As the fixing resin, a plastic having a softening point of 80 to 150 ° C. and a glass transition point of 50 to 80 ° C., for example, vinyl aromatic such as polystyrene satisfying these conditions, so that the below-described flash heat fixing can be satisfactorily performed. Resin, acrylic resin, olefin resin, epoxy resin, polyester resin and the like are preferably used. The toner particle size is 3 to 25 μm, preferably 5 to
12 μm is desirable to obtain good print quality.

On the downstream side of the photosensitive drum 61, a plurality of (three in this embodiment) fixing flash exposure lamps 67 and a reflection cover 68 thereof are arranged in proximity to the moving bag 1. Each exposure lamp 67 has its own ON-OF.
Power source 69 with built-in F switch 69a (eg DC15
00-1800 volts). Switch 69a
Is turned on at the moment when each push-up tool 25 comes directly under the exposure lamp 67 (for example, for a short time of 1 msec.) At the timing of intermittent rotation of the printing turret 4, and then until the next push-up tool 25 comes directly under. It is controlled by a control device (not shown) so as to be turned off. The flash exposure lamp 67 has a near infrared region (wavelength 0.7 to 1.
A lamp having an emission spectrum of 2 μm),
Particularly, a xenon lamp is preferably used from the viewpoint of availability. The exposure energy per unit area on the irradiation surface of the plurality of lamps 67 varies depending on the moving speed of the bag 1, but is usually 0.2 to 10 J / cm ² , particularly 1 to 3 J / cm ^2.
Are preferred. Total irradiation time is 0.1-10m
sec. Especially 0.5 to 3 msec. In a short time. For satisfactory thermal fixing by flash exposure,
As shown in the experimental example described later, the surface tension (according to the measuring method of JIS K6768) of the printing portion 6 of the bag 1 is 36 dy.
It is preferably n / cm or more and the plastic of the bag 1 does not substantially absorb in the near infrared region. This is because if the surface tension is smaller than 36 dyn / cm, the fixing property of the toner on the printing portion 6 is lowered and the printed image 8 is easily peeled off. Therefore, the original surface tension is 3
When printing on the bag 1 made of plastic smaller than 6 dyn / cm, flame treatment, corona discharge treatment,
It is desirable to preliminarily perform a surface treatment such as a primer treatment or a chemical treatment so that the surface tension becomes 36 dyn / cm or more. Examples of plastics that do not substantially absorb in the near infrared region include polyethylene, polyester, polypropylene and nylon.

Below the printing turret 4, a delivery conveyor 5 moving in the direction of arrow C is provided for placing the bag 1 in which the printing unit 6 is naturally dropped after fixing, and sending it to the next step after fixing. It is set up.

The bag 1 is printed by the above apparatus 100 as follows. The bag 1, which has been deflated in advance and whose body portion 1b is substantially flat, is placed and conveyed on a conveyor (not shown), and the printing portion 6 is moved to the position shown in FIG.
The upper chutes 10 are successively loaded so as to face the right side of the. When the air cylinder 14a operates based on a signal from the proximity switch 36 and the stopper 13a opens for a very short time in which only one bag 1 falls, the bag 1 naturally falls along the upper chute 10, After passing between the corona-treated rolls 11, the surface tension of the body portion 1b is 36 dyn /
After being surface-treated so as to be cm or more, the lowering is stopped by the stopper 13b of the lower chute 12 and stands by. When the stopper 13b is opened based on the signal from the proximity switch 36, the stopper 13b descends again, and is stopped by the stopper 13c and waits at the gripping station P at the lower end 12x of the lower chute 12.

When the vacuum suction device 17 of the transfer turret 3 reaches the gripping station P and stops, the air cylinder 21 operates, the piston rod 21a advances, and the vacuum cup 19 moves the upper surface of the body 1b of the bag 1 ( The surface on the right side in FIG. 3) is gripped by vacuum suction. After gripping, the piston rod 21a retracts, and in this state, the bag 1 moves in the direction of arrow A, reaches the transfer station Q, and stops. At the same time, the push-up device 25 of the push-up device 24 of the printing turret 4 in the state of FIG. 4, that is, in the lowered position comes to the transfer station Q and stops, and the body portion 1b of the bag 1 pushes the push-up device 25.
Then, it is placed so that the height direction thereof is perpendicular to the revolving direction of the push-up tool 25.

Immediately, the air cylinders 39 and 51 are actuated, the pressing portions 38a and 48a are raised, and are separated from the pins 34d and 47b, respectively.
Contracts and the suspending portion presser 34c presses the suspending portion 1c strongly against the upper surface 33a of the suspending portion receiver to grip the suspending portion 1c, and at the same time, the spring 46 also operates to lower the mouth retainer 47a to lower the mouth. The mouth portion 1a is gripped in cooperation with the portion receiver 43. The vacuum of the vacuum cup 19 is released, the air cylinder 21 operates, the piston rod 21a rises, the transfer turret 3 rotates, and the vacuum cup 19 separates from the bag 1. Immediately when the printing turret 4 rotates, the air cylinder 2
8 operates to raise the piston rod 28a. Then, the mouth portion 1a of the bag 1 in which the hanging portion 1c is gripped is pulled downward together with the mouth portion retainer 47a and the mouth portion receiver 43 by the elastic resistance of the spring 42, and at least the upper and lower walls of the printing portion 6 of the body portion 1b. However, as shown in FIG. 8, they come into close contact with each other without any slight gap (FIGS. 5 and 8).

In this state, the bag 1 moves in the direction of arrow B, the printing unit 6 moves and comes into contact with the photosensitive drum 61, and an image corresponding to the printed image 8 produced by the computer and stored in the memory is displayed. The toner image is transferred by the photosensitive drum 61 in the form of a toner powder image, and the powder image is formed on the printing unit 6. Bag 1 moves further and flash lamp 6
While moving toward 4, the powder image is heat-fixed and a printed image 8 is formed. The melted toner is absorbed by the bag 1 and immediately cooled and solidified. After that, the bag 1 drops onto the delivery conveyor 5 and is transferred to the next step.

Next, the experimental results of the influence of the surface tension of the bag 1 on the fixing property of the printed image 8 will be described. The bag 1 made of low-density polyethylene having a softening point (JIS K7206) of 107 ° C. was loaded into the upper chute 10 of the printing apparatus 100 shown in FIG. 3 while the transfer turret 3 and the printing turret 4 were stopped. Then, the corona-treated roll 11 was passed through to form five bags 1 each having various surface tensions. After that, the transfer turret 3 and the printing turret 4 are operated, and these bags 1 are passed through the chutes 10 and 12 with the power supply 15 of the corona treatment roll 11 being turned off, and the paragraph numbers 0023 to 002 are used.
As described in 5, transfer and fixing to the printing unit 6,
Fifteen 10 mm * 10 mm square figures were printed. The electrical corona treatment conditions of Samples 1, 2, 3, 4 and 5 are the same as the output of 0.25 kw and 33 kHz, and the speed of the corona treatment roll 11 is 0.5 m / min, 1 m / min and 4 m, respectively.
/ Min, 8 m / min and 12 m / min. The toner is mainly composed of a fixing resin (epoxy resin having a softening temperature of 128 ° C. and a glass transition point of 75 ° C.) and a black colorant (carbon black) and containing 90% by weight of the fixing resin. Using. The toner particle size was about 8.8 μm. A xenon lamp was used as the exposure lamp 67. The exposure energy per unit area on the irradiation surface of the three lamps 67 is ² J / cm ² , the moving speed of the bag 1 in the printing turret 4 is 10.8 m / min, and the stop time is 0.4 seconds. there were. Samples 1, 2, 3, 4 and 5
Surface tension of 50dyn / cm and 45dyn, respectively
/ Cm, 38 dyn / cm, 35 dyn / cm and 3
It was 0 dyn / cm. A commercially available cellophane tape was attached to each sample, and a tape peeling test was performed in which the tape was vigorously peeled in the direction of about 30 degrees. No peeling of the printed image was observed in Samples 1, 2, and 3, but slight peeling was observed in Sample 4, and completely peeled in Sample 5.

The present invention is not limited to the above embodiments, and for example, although not shown, a projection which can be inserted into the hole 1c1 of the suspension 1c is provided on the suspension receiver 33 and / or the suspension retainer 34c. Before pushing up the bag 1 placed on the push-up tool 24, insert this convex portion into the hole 1c1,
The hanging portion 1c may be gripped more west. The container may have a shape other than a bag. In this case, it is preferable to provide a fin-shaped portion corresponding to the hanging portion 1c on the bottom portion during blow molding from the viewpoint of gripping the bottom portion when pushing up the body portion. If unnecessary at the time of use, the fin-shaped part may be cut and removed after printing. The container material may be a thermoplastic such as polyester, polypropylene and nylon. The surface treatment of the printing portion may be performed by flame treatment, primer treatment, chemical treatment or the like.

[0033]

According to the first aspect of the present invention, it is possible to print a plastic container such as a plastic bag having a body portion that is soft and easily dented, and the two opposite wall portions are easily in close contact with high productivity. It also has the effect of being suitable for high-mix, low-volume printing. The invention according to claim 2 has an advantage that the printing portion is less likely to be peeled off, the container is not likely to be damaged by exposure to heat such as thermal deformation, and printing can be performed with high productivity. The invention according to claim 3 relates to an apparatus directly used for carrying out the invention according to claim 1, and has the same effect as the invention according to claim 1. In the gripping device of the invention according to claim 4, the plastic container is automatically placed on the push-up tool of the printing turret,
Further, since it can be automatically separated from the plastic container after being placed, it has an advantage that high productivity can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of an example of a plastic container that is the subject of the present invention.

FIG. 2 is a side view of the plastic container of FIG. 1 taken along line II-II.

FIG. 3 is an explanatory front view of an apparatus according to an embodiment of the present invention.

FIG. 4 is a partially cut front view taken along line IV-IV of FIG. 3, showing the push-up tool in a lowered state.

FIG. 5 is a partially cut front view taken along line VV of FIG. 3, showing the push-up tool in a raised state.

FIG. 6 is a plan view of FIG.

FIG. 7 is a longitudinal sectional view of an essential part taken along the line VII-VII of FIG.

FIG. 8 is a side view of the main part as seen from the line VIII-VIII in FIG.

[Explanation of symbols]

1 Plastic Bag (Plastic Container) 3 Transfer Turret 4 Printing Turret 7 Revolution Trajectory Surface 8 Printed Image 16 Pushing Surface 17 Vacuum Suction Device (Gripping Device) 19 Vacuum Cup (Gripping Device) 21 Air Cylinder (Mounting Container Body on Pushing Tool) Device for placing; device for separating gripping device from container; device for advancing and retracting vacuum suction cup 21a Piston rod (device for mounting container body on push-up tool; device for separating gripping device from container; vacuum suction Device for moving the cup forward and backward) 25 Push-up tool 28 Air cylinder (device for bringing both wall parts of the body into close contact) 28a Piston rod (device for bringing both wall parts of the body close together) 33 Suspended part receiver (both ends of container) 34c Suspension part retainer (device for grasping both ends of container) 39 Air cylinder (equipment for grasping both ends of container) 43) Mouth receiving part (device for holding both ends of the container) 47a Mouth holding part (device for holding both ends of the container) 51 Air cylinder (device for holding both ends of the container) 56 DC power supply ( Bias voltage) 60 Electrophotographic unit 61 Photosensitive drum 67 Flash exposure lamp (heat fixing device) 100 Printing device P gripping station Q transfer station R transfer station S fixing station

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Imaya 3-65 Otsucho, Yokosuka City, Kanagawa Prefecture

Claims (4)

[Claims] 1. A method for printing a blow-molded plastic container in which a body is easily dented, wherein a shape of a part of a cylindrical surface, which is a revolution locus surface in an ascending state, provided on an intermittently rotating printing turret is used. The container is placed on the push-up tool having the push-up surface, which is in the descent state while the push-up tool is in the lowered state, the both ends of the container are grasped, and the push-up tool is immediately raised when the push-up tool revolves. Then, the two opposite wall portions of the body of the container are brought into close contact with each other, and the toner is powdered under a bias voltage applied to the push-up tool by electrophotography on the surface of the close portion while revolving the push-up tool. A method for printing a plastic container, which comprises transferring the image in a form and then exposing the powder image to fix the toner. 2. The surface tension of the surface of the body of the plastic container to be printed is 36 dyn / cm or more, and the plastic constituting the container does not substantially absorb in the near infrared region. The method for printing a plastic container according to claim 1, wherein the toner contains a fixing resin and a colorant and has a near-infrared absorbing property, and the powder image is exposed by flashing in the near-infrared. . 3. A printing device for a blow-molded plastic container, in which the body portion is easily dented, the device comprising: a holding device for the container; a plurality of push-up tools having a push-up surface on the surface at equal intervals in the circumferential direction, A printing turret that is intermittently rotated and provided with a transfer station, a transfer station, and a fixing station in this order along the rotation direction, and the pressing surface has a shape of a part of a cylindrical surface that is the revolution trajectory surface when it is in an ascending state; In the station, a device for placing the body of the container gripped by the container gripping device on the push-up tool in the lowered state during the period when the printing turret is stopped; Device for gripping both ends; Device for separating the container gripping device from the container during the stop period; Immediately as the printing turret rotates, the push-up tool is lifted to A device for bringing the opposite wall parts into close contact with each other; arranged at the transfer station so as to be able to contact the body part,
A photosensitive drum of an electrophotographic unit that transfers a print image in the form of a toner powder image to the revolving body; a DC power supply for applying a bias voltage to the push-up tool, and heat the powder image provided at the fixing station. A printing device for a plastic container, comprising a fixing device. 4. The transfer turret, which intermittently rotates and stops at the same time as the printing turret at the transfer station, has a plurality of gripping devices for plastic containers arranged at equal intervals in the circumferential direction, and the gripping device grips the container. 4. The printing apparatus for a plastic container according to claim 3, further comprising a vacuum suction cup for moving the vacuum suction cup forward when gripping, and retracting the vacuum cup when moving away from the container.