JPH052507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of printing plastic bags. In more detail, we mainly focus on finished plastic bags, including those with handles and gussets, as well as vinyl films with designs, store names, and other characters.
Concerning a method for printing symbols in small batches.

[Prior Art] Printing on conventional plastic bags is carried out by continuous printing that is performed before bag manufacturing.

Continuous printing is as shown in Figure 16.
In this method, a vinyl film 81 wound around a single roll 80 is passed between printing machines 82 as a continuous body and printed. The printed vinyl film 81 is then wound onto the winding body 83 again. Afterwards, the vinyl film 81 is unwound from the printed roll 83, put through a special bag-making machine, and processed into a bag by following the steps of folding, gluing the handle, heat-sealing, and cutting. It is. In this case, the same type of printing is applied to the finished plastic bag.

[Problems to be solved by the invention] In the case of the above continuous printing, one roll of roll 8
0 is usually 3000 to 5000 m, and the same printing will be done on all of this, so for example 6000 to 10000 m.
Although it is suitable for printing in large quantities, such as around 100 to 3,000 sheets, it is not cost-effective for printing small lots, such as 100 to 3,000 sheets, and the work efficiency is low, so it is currently not widely used. It is.

In view of the above circumstances, it is an object of the present invention to provide a printing method suitable for printing on plastic bags in small lots.

However, when printing on a plastic bag after the bag is completed, there are the following problems.

Completed plastic bags are usually folded and packaged in outer bags or cardboard boxes.
When a plastic bag is unpacked and taken out for printing, there are often wrinkles on the surface of the plastic bag. Such wrinkles may cause missing print or interfere with the normal operation of the printing press.

In view of the above circumstances, it is an object of the present invention to provide a printing method that can print on plastic bags with high quality and high efficiency.

[Means for Solving the Problems] The method of printing plastic bags of the present invention is a method of printing each independent plastic bag one by one, and includes (a) printing in a direction perpendicular to the feeding direction to the printing device; A plastic bag is placed on a transverse conveyor that is fed at high speed, and while the plastic bag is fed horizontally at high speed on the conveyor, a presser member placed on the top of the conveyor presses the plastic bag on the conveyor to remove wrinkles from the plastic bag. (b) A stopper provided at the intersection of the horizontal conveyor and the extension line of the advance conveyor that feeds the vinyl in the direction of the printing device, the vinyl conveyed by the horizontal conveyor is The bag is stopped, the printing position of the plastic bag is determined, and (c) the plastic bag is placed on the forward conveyor, and while the plastic bag is being forwarded by the conveyor, the presser member disposed on the upper surface of the conveyor While pressing the plastic bag on the conveyor to straighten the wrinkles in the bag, feed the plastic bag to the printing device, (d)
The method is characterized in that the plastic bag is then printed using a printing device.

Note that in this specification, a "plastic bag" refers to a bag made of synthetic resin such as polyethylene or polyvinyl chloride.

[Function] In the printing method of the present invention, when a plastic bag is fed by a transverse conveyor, it is sandwiched between the conveyor and the holding member at high speed, thereby stretching the plastic bag and removing wrinkles. Furthermore, since the plastic bag is pressed from above by the pressing member when being fed on the advance conveyor, wrinkles are corrected. In this way, according to the present invention, the wrinkles in the vertical direction and the horizontal direction of the plastic bag are sequentially smoothed out, so that the printing process is carried out smoothly. Moreover, since wrinkles are removed at the same time during the supply process, printing efficiency is also high.

The stopper positions the plastic bags when they are transferred from the lateral conveyor to the front conveyor, so each individual plastic bag is individually positioned, making it easy to manage the printing position. becomes.

In the present invention, it is possible to print on a vinyl bag that has been subjected to continuous printing before bag making, or it is also possible to print on a plastic bag that has not been subjected to continuous printing.

In the former case, for example, plastic bags with a basic design printed on them can be produced in large quantities, and then plastic bags printed with store names, unique patterns, etc. can be produced in small batches. In the latter case, only the store name and one-point pattern will be printed, but of course it is also possible to print in small lots.

[Example] Next, embodiments of the present invention will be described.

Figure 1 is an explanatory diagram showing the printing method of the present invention, Figure 2 is an explanatory diagram showing the printing method of the present invention.
The figure is a block diagram showing the printing method of the present invention, FIG. 3 is a perspective view of a supply mechanism for carrying out the cross-feeding process and the forward-feeding process of the present invention, and FIG. 4 is a block diagram of a printing machine used in the printing method of the present invention. A schematic side view of the register mechanism, FIG. 5 is a plan view of the feed roller 27, and FIG.
The figure is a schematic side view of the inking device in the printing press, FIG. 7 is a perspective view showing the ink forming roller and doctor, FIG. 8 is a front view showing the plate cylinder and impression cylinder, and FIG. 9 is the elevating mechanism of the impression cylinder. Explanatory diagram, 10th ~
Figure 11 is a side view and rear view of the guide roller, the first
Fig. 2 is a perspective view of a typical type of plastic bag printed by the printing method of the present invention, Fig. 13 is an end view taken along the - line in Fig. 12, and Figs. 14 and 15 are perspective views of other plastic bags. be.

First, the printing method according to the present invention will be explained based on FIG. The continuous printing process and the bag making process are the same as the conventional ones, and then a small lot printing process is performed according to the present invention.

In the continuous printing process, the vinyl film 71 wound on the roll body 70 is passed as a continuous body through a printing machine 72, the desired printing is applied, and the printed vinyl film 71 is placed on the roll body 73 again. This is done by winding it up. In this case, a known printing machine is used as the printing machine 72, and one printing machine 72 is used for monochrome printing, and a plurality of printing machines are used for multicolor printing. Note that if printing is not necessary, the roll 70 may be directly applied to a bag making machine without passing it through the printing machine 72.

A dedicated bag-making machine is used in the bag-making process.

A printed roll 73 or an unprinted roll 71 is applied to this bag-making machine. The bag making process is normally performed in the following order: folding 74, forming handles 75, sealing 76 at required locations, and cutting 77 for each bag, but the steps may differ slightly depending on the type of bag making machine. In any case, in this process, the continuous vinyl film is made into an independent plastic bag 50 one by one, which has a completed bag form.

A small lot printing step is then performed according to the method of the present invention. In carrying out the printing method of the present invention, only one type of plate may be used depending on the printing content, or a large number of types may be prepared and an appropriate plate may be selected and used. The figure shows 4
Three types of versions are shown: a, 4b, and 4c,
Of course, four or more types cannot be used interchangeably. The plate is attached to the plate cylinder so that it can be easily replaced.
It is preferable that the plate is made of resin and bonded with an adhesive.
By changing the plates 4a, 4b, and 4c for each lot, it is possible to easily perform many types of printing Pa, Pb, and Pc.

Plastic bags suitable for printing according to the present invention include: Note that this is an example and is not limited to this.

The plastic bag 50 shown in FIGS. 12 and 13 has gussets 57 and 58 at the opening and the bottom.
A handle 55 is usually attached to the center of the opening. Such a plastic bag 50 has a gusset of 57,
58, the thickness is partially different,
Care must be taken to apply the appropriate printing pressure to the area to be printed (in most cases the body portion 51). Furthermore, the handle 55 must not interfere with the operation of the printing press.

The plastic bag 50 shown in FIG.
7 and 58 are attached to both sides, and the handle 55
is formed by drilling a hole 59. Furthermore, the plastic bag 50 shown in FIG.
5 is formed. In both cases, the store name and other information are printed on the main body.

Next, the small lot printing process, that is, the outline of the printing method of the present invention will be explained based on FIG. Generally speaking, in the cross-feeding process (), the plastic bag that is the printing material is fed horizontally while smoothing out the wrinkles, and then
3 and 14, the final positioning of the plastic bag during printing is performed in the register step (), and the ink on the plate 4 is transferred during one rotation of the plate cylinder 1 and the impression cylinder 2 in the printing step (). Printing is performed on the plastic bags, and the printed plastic bags are sent to the collection station S in the discharge process ( ).

Further, the above steps will be explained in detail with reference to FIGS. 3 to 11.

In the cross-feeding step (), as shown in FIG. 3, the plastic bags obtained in the previous bag-making step (shown in FIG. 2) are first transferred onto the workbench 5a on the left side of the cross-feed table 5 in the figure. placed in

The illustrated plastic bag 50 is the same as that shown in FIG. 12 earlier, and has a handle 55 and a gusset 5.
It has 7,58. In addition, 59 is a wrinkle formed when it was folded.

Now, the plastic bags 50 on the workbench 5a are manually fed one by one onto the transverse feed conveyor 7. Note that the air may be fed automatically using an appropriate air feeding mechanism. In that case, the plastic bags 50 can be extracted one by one from the bottom of the stacked plastic bags 50 and supplied.

The lateral conveyor 7 moves in the direction of arrow T, and its speed is about three times that of the forward conveyor 9. A holding plate 11 is placed on each conveyor belt 7a. This holding plate 11 is a "holding member" referred to in the claims, and is an elongated steel plate curved in the longitudinal direction. The front end thereof is slightly raised and fixed to the support frame 12, and the rear end thereof is brought into contact with the conveyor belt 7a by its own weight. Therefore, the plastic bag 50 sent to the transverse conveyor 7 is sandwiched between the conveyor belt 7a and the presser plate 11 and is transversely fed at high speed, thereby removing the wrinkles 59 formed on the plastic bag 50. is stretched and flattened.

Furthermore, a stopper 13 and a stopper 14 are provided on the traverse conveyor 5 at right angles to the traverse conveyor 7, and in parallel to the traverse conveyor 7, respectively.

Since the installation positions of the stoppers 13 and 14 can be changed freely, the fixing positions may be changed depending on the size of the plastic bag 50. The plastic bag 50 sent by the horizontal conveyor 7 is stopped at the stopper 1.
3 and 14, and the printing position in the lateral feed direction is determined at that position.

Note that the lateral feed table 5 is attached to the tip of the front feed table 6 so as to be freely tiltable, and can be moved up and down in the direction of arrow T as a whole. By changing the inclination angle of the transverse feed table 5 in this manner, the transverse feed can be stabilized regardless of the size and weight of the plastic bag 50.

The material is sent from the lateral conveyor 7 to the forward conveyor 9 by a suction transfer device 8.

The suction transfer device 8 uses a suction cup 15 to pick up a plastic bag 50.
In the illustrated device 8, two suction cups 15 are fixed to a support frame 16. Then, repeat the reciprocating motion according to the trajectory shown by the chain line 17, removing one plastic bag 50 for each movement.
to be delivered.

When the plastic bag 50 is sent to the advance conveyor 9 by the suction transfer device 8, the advance step () begins. The advance conveyor 9 that executes the advance step ( ) is driven in the direction of arrow F, and four presser rollers 18 are in contact with its upper surface. Therefore, the plastic bag 50 sent by the conveyor 9 is held down from above and is sent reliably. The support structure for each of these presser rollers 18 is arbitrary and can be freely designed, but it is possible to freely move each presser roller 18 in the feeding direction of the conveyor 9 (i.e., the front and back direction), in the lateral direction, and even in the vertical direction. Preferably, the position can be adjusted. Further, although the illustrated presser rollers 18 are supported by a support shaft 19, each roller 18 may be supported independently by appropriate means without using the support shaft 19. In any case, the plastic bag 50 printed in this manner is pressed by each presser roller 18 in accordance with the position of the gussets 57 and 58, and is reliably fed.

Furthermore, a presser plate 22 is attached to a frame 21 that supports the support shaft 19 of the presser roller 18. This holding plate 22 is a "holding member" referred to in the claims, and is the same as the steel plate 11 used in the traverse conveyor 7. A wide resin sheet 23 is adhered to the lower surface of the sheet. The plastic bag 50 conveyed on the conveyor 9 is passed under the sheet 23 which is held down by the weight of the presser plate 22, so that it is sandwiched between the sheet 23 and the conveyor belt 9, and the wrinkles of the plastic bag 50 are pushed out. Since wrinkle smoothing in this step is performed in a direction perpendicular to that in the previous cross-feeding step, wrinkles on the plastic bag 50 are removed so as not to interfere with printing. Since the resin sheet 23 has a large area, it is possible to stably feed both large and small plastic bags without lifting them up.

The rear end of the forward conveyor 9 is connected to a register mechanism, and the plastic bags 50 conveyed by the forward conveyor 9 are then sent to the register mechanism.

When the plastic bag 50 is fed in this step, the plastic bag 50 is fed so that the handle 55 of the plastic bag 50 is positioned in the lateral direction (that is, in the direction perpendicular to the forward feeding direction). This is important in order to allow the handle 55 to pass through the notch 46 at one end of the plate cylinder 1 and the impression cylinder 2 so that it does not interfere with printing in the later printing process.

The register process () will be explained based on FIG. The register step () is to temporarily stop the feeding of the plastic bag 50 and correctly adjust the printing position of the plastic bag 50 before the printing step () begins. In the same figure, 25 is a pre-inspection, which is fixed to a roller 26. As the roller 26 rotates, the front check 25 is tilted in the direction of the stop mark G. A feed roller 27 is disposed above the roller 26 so as to be movable up and down, and when the feed roller 27 descends and rotates, the plastic bag 50 can be advanced. On the left side of the front detection 25 in the figure, a light emitting element 28 and a light receiving element 29 of a phototube are arranged vertically facing each other, so that it can be detected that the plastic bag 50 has advanced this far.

Note that the feed roller 27 is fitted onto a support shaft 32 as shown in FIG.
2 is fixed to the tip of an arm 33 that is swingably attached to a fixed shaft 34. By sliding the feed roller 27 on the spindle 32, the mounting position is changed between the plastic bag 50 which is the printing material, the gussets 57 and 58, and the main body 51.
It is designed so that it can be pressed separately.

Assuming that a plastic bag 50 is now being sent by the forward feed conveyor 9, the front edge of the bag 50 is at the front check 2.
5, the forward movement of the bag 50 stops. Then, when the feed roller 27 descends and rotates in the direction of the arrow,
At the same time, the rollers 26 rotate to tilt the front checker 25 forward and send the bag 50 forward while pinching the bag 50. When the plastic bag 50 moves forward slightly, it blocks the light beam between the light emitting element 28 and the light receiving element 29, and this is used as a detection signal to activate the solenoid 48 that drives the impression cylinder 2 to the printing position. In this way, the printing position of the plastic bag 50 in the forward feeding direction of the plastic bag 50 is determined, and at the same time, the printing devices 1 and 2
A plastic bag 50 is sent inside.

Next, the printing process () begins, but before that, the inking device will be explained based on FIGS. 6 and 7. The ink applicator roller 3 has a square pattern (hereinafter referred to as an anictic pattern 36) with minute depressions like a gravure cell on the entire surface.
It is an Anitskus roller with a The ink applicator roller 3 is in contact with the plate cylinder 1 and is directly immersed in ink 38 contained in an ink tray 37, to which ink 38 is supplied and discharged by a pump 39. ink 38
Liquid flexo inks such as pigment inks dispersed in solvents or dyes dissolved in alcohols are used, but inks with high quick-drying properties are particularly suitable. In this case, even if the printed plastic bags 50 are stacked one above the other, no printing stains will occur, so the printing speed can be increased.

A doctor 41 is in contact with the surface of the ink application roller 3, and the doctor 41 inks the ink 3.
8 is scraped off, and the ink 38 is left only in the aniculates 36. The amount of ink to be transferred to the plate 4 is basically determined by the cell volume of the anitic grid 36, so several ink applicator rollers 3 with different cell volumes are prepared, and the amount of ink to be transferred to the plate 4 is determined depending on the type of printed matter. It is recommended that you replace it as appropriate. Furthermore, since the amount of ink can be regulated using the doctor 41, quantification and uniformity of ink application can be achieved.

The ink applicator roller 3 rotates as the plate cylinder 1 rotates, and transfers the ink 38 adhering to its surface to the surface of the plate 4. This operation is performed every rotation of the plate cylinder 1.

The printing process () will be explained based on FIGS. 8 and 9. The printing process () is carried out by passing the plastic bags 50 one by one through a printing device consisting of a plate cylinder 1 and an impression cylinder 2. The plate cylinder 1 has a main body portion 42 to which the plate 4 is attached, and a relief portion 43 having a small diameter is formed at one end thereof. Similarly, the impression cylinder 2 has a main body portion 44 to be pressed against the plate 4, and a relief portion 45 having a small diameter is formed at one end thereof. Since the relief portion 43 of the plate cylinder 1 and the relief portion 45 of the impression cylinder 2 are both provided at the end of the same side, a cutout portion 46 is formed between the relief portions 43 and 45 facing each other. . This notch 4
6, when the plastic bag 50 to be printed is passed between the plate cylinder 1 and the impression cylinder 2, the handle 55 can pass through without getting caught on anything during printing.

A plate 4 is attached to the surface of the plate cylinder 1. A letterpress plate made of resin is used as the plate 4, and its dimensions and attachment position can be freely selected. By appropriately selecting the size and adhesion position of the plate 4, the main body portion 51 between the gussets 57 and 58 of the vinyl 50 is
It is possible to print only on the gussets 57 and 58 or only on the gussets 57 and 58.

The impression cylinder 2 is supported at one end by a crank 47, and the lower end of the crank 47 is connected to the solenoid 4.
It is connected to 8. This solenoid 48 is connected to the photocells 28 and 29 previously explained in the register process ().
It is activated by the detection signal and pushes the impression cylinder 2 upward. As a result, the plate cylinder 1 and the impression cylinder 2 are pressed together with an appropriate printing pressure. Therefore, the plastic bag 50 that has been positioned and fed in the register process () is correctly sandwiched between the plate cylinder 1 and the impression cylinder 2, and
It is pressed against the plate 4, and is printed and sent out while the plate cylinder 1 and impression cylinder 2 rotate once.

The printed plastic bags 50 are No. 10 to 11.
It is guided downward by guide rollers 61 and 62 as shown in the figure and sent out. Guide roller 61
and guide roller 62 are arms 63 and 64, respectively.
and is attached to a shaft 65. A tension spring 66 is stretched between the support shaft 61a of the roller 61 and the support shaft 62a of the roller 62, so that the rollers 61 and 62 are drawn to each other. The guide roller 61 is in contact with an obliquely upper portion of the impression cylinder 2, and the guide roller 62 is in contact with a portion slightly below the right side of the impression cylinder 2, supported by a stay 67. Therefore, the plastic bag 50, which is the printing material, sent out from between the plate cylinder 1 and the impression cylinder 2 is guided by guide rollers 61, 62 and sent downward.

The printed plastic bag 50 sent downward from the impression cylinder 2 in this way is transferred to the next discharge process ().
is sent to the collection station S by the . The discharge process () is carried out using a conveyor 68 disposed below the impression cylinder 2 and a roller conveyor 69 connected thereto.
It will be held in Note that a drying device H may be disposed above the roller conveyor 69 if necessary. When drying the ink on the printed plastic bags 50 sent on the roller conveyor 69 by the drying device H, printing stains will not occur even if the plastic bags 50 are stacked one on top of the other when stacking.

Next, the advantages of the printing method of this embodiment will be explained.

In the above embodiment, the printing plate 4 is a letterpress printing plate, and when it is attached to the surface of the printing cylinder 1, only the printing plate surface protrudes, so that the plastic bag 50, which has gussets 57, 58, etc., and whose thickness is not constant, is attached. Even in contrast, printing can be performed with appropriate printing pressure, resulting in high printing quality.
Further, by changing the size of the printing plate 4 and the adhesion position, it is possible to avoid or print on the gusset part of any type of plastic bag 50. In the normal printing method, the handle 55 of the bag gets caught between the plate cylinder and the impression cylinder or other mechanical parts and interferes with normal operation, but in the space between the plate cylinder 1 and the impression cylinder 2 46 eliminates any chance of jamming or the like, so even if the bag is a plastic bag with a handle 55 attached, it will not interfere with printing.

Furthermore, it is possible to print about 2,400 to 3,000 plastic bags 50 of various shapes with handles 55 and gussets 57 and 58 per hour, depending on the size. Therefore, it is ideal for so-called small lot printing, where the number of copies is too small to be printed using conventional continuous printing methods, but is too large for home printing machines, etc., and it is a low-cost printer that meets such demand. You can respond with

As described above, the printing method of this embodiment can print on various types of plastic bags, but it is of course possible to print on plastic bags in other forms as well. Furthermore, it is not limited to vinyl bags, but can also be printed on paper or canvas bags, and can also be printed on simple vinyl films that are not made into bags.

[Effects of the Invention] According to the printing method of the present invention, it is possible to print small lots of plastic bags, etc., which has not been achieved in the past, at low cost and with high efficiency.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the printing method of the present invention, Figure 2 is an explanatory diagram showing the printing method of the present invention.
The figure is a block diagram showing the printing method of the present invention, FIG. 3 is a perspective view of a supply mechanism for carrying out the cross-feeding process and the forward-feeding process of the present invention, and FIG. 4 is a block diagram of a printing machine used in the printing method of the present invention. A schematic side view of the register mechanism, FIG. 5 is a plan view of the feed roller 27, and FIG.
The figure is a schematic side view of the inking device in the printing press, FIG. 7 is a perspective view showing the ink forming roller and doctor, FIG. 8 is a front view showing the plate cylinder and impression cylinder, and FIG. 9 is the elevating mechanism of the impression cylinder. Explanatory diagram, 10th ~
Figure 11 is a side view and rear view of the guide roller, the first
Fig. 2 is a perspective view of a typical type of plastic bag printed by the printing method of the present invention, Fig. 13 is an end view taken along the - line in Fig. 12, and Figs. 14 and 15 are perspective views of other plastic bags. FIG. 16 is an explanatory diagram of a conventional continuous printing method and bag making method. (Main symbols in the drawing), 1: Plate cylinder, 2: Impression cylinder,
3: Ink application roller, 4: Plate.

Claims (1)

[Claims] 1. A method of printing individual plastic bags one by one, which includes: (a) placing the plastic bags on a transverse conveyor that feeds the bags at high speed in a direction perpendicular to the feeding direction to the printing device; (b) While the plastic bag is being conveyed horizontally at high speed on the conveyor, the plastic bag on the conveyor is pressed by a pressing member disposed on the top surface of the conveyor to straighten the wrinkles of the plastic bag while being conveyed horizontally; A stopper installed at the intersection of the transverse conveyor and the extension line of the advance conveyor that feeds the paper in the direction of the printing device stops the plastic bag being sent by the transverse conveyor, and changes the printing position of the plastic bag. (c) Then place the plastic bag on the forward conveyor,
While the plastic bag is being fed forward on the conveyor, the plastic bag on the conveyor is pressed down by a pressing member disposed on the upper surface of the conveyor to straighten the wrinkles of the plastic bag, and the plastic bag is fed to the printing device (d ) A printing method characterized in that the plastic bag is then printed using a printing device. 2. Claim 1, in which the plastic bag is fed by the advance conveyor with the handle of the plastic bag facing in a direction perpendicular to the feeding direction.
Printing method described in section. 3. Claims in which the printing device comprises a plate cylinder and an impression cylinder, and prints while passing a handle of a plastic bag through a notch formed at one end of each of the plate cylinder and the impression cylinder. The printing method described in item 1. 4. The printing method according to claim 1, wherein the printing position on the plastic bag is changed by changing the adhesion position of the resin letterpress plate on the plate cylinder.