Water-based inkjet printing machine capable of automatic operation

Abstract

To achieve an aqueous inkjet printer which enables automatic operation.SOLUTION: An aqueous inkjet printer enabling automatic operation has a printing database 5 for storing attribute data and printing data of a film, means 6 for supplying a film that is an object to be printed, and means of a print execution program for storing one or a plurality of printing commands composed of the attribute data and the printing data of the film that is the object to be printed, and a printing start, which is instructed by an operator, calls the specified printing data from the printing database according to the printing execution program, supplies a specified film that is the object to be printed, automatically sets an optimal dry condition and an optimal tension condition corresponding to the attribute data and the printing data of the film, automatically sets the discharge position that is registered according to expansion and contraction of the film when moving among the respective discharge heads, and executes all the printing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an aqueous inkjet printing apparatus capable of automatic operation, and more particularly to an aqueous inkjet printing apparatus capable of automatically printing on a film instead of paper.

Background Art

[0002] The applicant of the present application has already invented an invention capable of aqueous inkjet printing on a plastic film used for food packaging materials.

[0003] Unlike paper, a plastic film is a substrate that is difficult to absorb liquid. Therefore, at the time of printing, gravure printing using gravure ink with high coating film adhesion or flexographic printing using flexo ink has been adopted.

[0004] By the way, inkjet printing that does not require plate making and can generate a printing image from digital data is excellent in on-demand properties and should originally be useful for food packaging materials that must print various designs etc. at any time, but it could not be adopted.

[0005] The reason is that aqueous inkjet ink that can be used for inkjet printing lacks various physical properties such as abrasion resistance, alcohol resistance, oil resistance, and water resistance, and the ink easily falls off, resulting in weak coating film adhesion. In this case, gravure ink or flexo ink with high coating film adhesion has too high viscosity, so it is impossible to smoothly eject ink from the nozzle in inkjet printing where ink is ejected from the nozzle and adhered, and thus it could not be used.

[0006] In food packaging materials that are not fixed durable consumer goods with fixed types of designs etc. and are consumed in the short term, and moreover, various designs etc. must be printed at any time according to the contents, it is essential to increase the printing speed in order to improve production efficiency.

[0007] However, gravure printing and flexographic printing, which require preparing a printing plate for each new design and setting it up on the production line each time, require time for the printing process, limiting how much speed can be increased.

[0008] For example, in the case of food packaging materials printed with designs using gravure printing, the necessary pre-printing work (submission of artwork + plate making) and printing itself took a total of 12 days, and other post-processing (film lamination, finishing) took another 6 days, for a total of 18 days.

[0009] Furthermore, as mentioned above, gravure printing requires color separation and plate-making time, which inevitably results in a larger minimum order quantity. This forces customers to purchase more packaging materials than necessary, leading to waste.

[0010] On the other hand, while it is easy to choose to use inkjet printing, this requires a process of laminating a plastic film on the side of the printed layer to prevent the printed layer from coming into contact with the food when printing on the front side of the packaging material, which presents problems in terms of cost and time.

[0011] In relation to this, the present inventor has created the following invention. The first invention is characterized in that, when printing a pattern and / or characters on the front surface of a plastic film to be made up of food packaging material, the pattern and / or characters are inkjet printed using inkjet ink, and then a transparent inkjet ink is overprinted onto the printed area by inkjet printing (Patent Document 1).

[0012] Furthermore, the second invention is characterized in that, when printing a design and / or text on the front surface of a plastic film that is to constitute a food packaging material, the design and / or text are inkjet printed using inkjet ink, and then a transparent UV ink is overprinted (Patent Document 2).

[0013] Furthermore, the third invention is characterized in that, when printing a design and / or text on the front surface of a plastic film that is to constitute a food packaging material, the design and / or text are inkjet printed using inkjet ink, and then transparent EB ink is overprinted (Patent Document 3).

[0014] According to the invention of the present inventor, when printing a design or the like on the surface located on the front side of a packaging bag or the lid of a food container, even if inkjet printing is performed using water-based inkjet ink, a transparent inkjet ink, transparent UV ink, or transparent EB ink is overprinted on the printing area to protect the printed layer of the design or the like, so that the printed layer of the design or the like is not exposed.

[0015] Therefore, friction that can cause the printed layer of the design to become blurred or generate debris when it comes into contact with the back of the film during the printing process on packaging bags and lids and when the film is wound up, or when it comes into contact with other packaging materials, items, or people's fingers during distribution or display, is prevented.

[0016] On the other hand, since printing is completed using inkjet printing, which excels in on-demand capabilities, there is no need for the time required for the process of starting printing, such as gravure printing or flexographic printing, which require preparing plates for new designs and setting them up on the production line. This allows for faster production and can dramatically improve the production efficiency of food packaging materials, which require printing a wide variety of designs on demand depending on the contents.

[0017] The aforementioned invention breaks with the conventional technical wisdom that, in printing plastic films, water-based inkjet inks lack various physical properties such as abrasion resistance, alcohol resistance, oil resistance, and water resistance, causing the ink to easily rub off and resulting in poor coating adhesion, making them unsuitable for use. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] Japanese Patent Publication No. 2021-88171 [Patent Document 2] Japanese Patent Publication No. 2021-88410 [Patent Document 3] Japanese Patent Publication No. 2021-88409 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0019] As described above, the present invention addresses the technical challenge of automatically operating a water-based inkjet printing system that offers excellent on-demand capabilities and enables the printing of small batches of diverse products.

[0020] To handle small-lot, high-mix production with extremely short lead times, water-based inkjet printing machines need to operate 24 hours a day. This makes it particularly difficult to secure workers for night shifts. To solve this problem, automated operation of water-based inkjet printing machines that can operate unattended is desirable.

[0021] Automating the operation of a printing apparatus is something that can be easily conceived by those skilled in the art. However, the inventor of the present invention, who performed water-based inkjet printing on plastic film—a feat no one had attempted before—faced a new problem in this regard.

[0022] In water-based inkjet printing, where the inkhead (printing unit) is non-contact, the tension of the printing inkhead and the film traveling through the drying path are under the same conditions. As a result, thermal expansion and contraction of the film occurs due to the influence of the drying temperature and the tension in the drying path, making it impossible to control the registration and dimensions.

[0023] Since the printing designs have different coverages depending on the individual printing density and range, the drying temperature and speed of the printing conditions vary each time. Although printing is possible by fixing the drying temperature and speed within a safe range, for example, when the coverage is low, the speed can be increased according to the drying capacity of the printing machine. To confirm this, trial printing must be performed each time printing is done, and the drying limit must be confirmed. At the very limit, ink adheres to the guide rolls in the drying oven, so this cannot be confirmed before printing. Therefore, even in printing where the speed can be increased, printing can only be done at the low safe speed.

[0024] Furthermore, even if the optimal conditions for the drying temperature and speed are known in advance, even if the types of various films used as the printing substrate, their thicknesses, and the paper widths are different, it will affect the printing alignment and the finished dimensions. Therefore, at the time of the first printing, it is necessary to select the optimal tension under the drying temperature and speed conditions determined in advance. Here too, trial printing is required many times for this purpose. This trial printing involves adjusting the alignment many times and stopping the printing to take samples, so it is not suitable for printing automation.

[0025] Figure 4 is a conceptual diagram showing the flow of film F in an aqueous inkjet printing apparatus. In an aqueous inkjet printing apparatus, achromatic inks such as white will mix with chromatic inks such as KCMY if printed simultaneously. Therefore, after printing the chromatic ink (Figure A in the figure), the ink is dried in the drying path, and then the achromatic ink is printed (Figure B in the figure) and dried. As is clear here, the film will expand and contract due to heating while moving between the ejection heads that print the ink. Therefore, the position of the ejection head for the achromatic ink must be set in anticipation of this expansion and contraction. If this is not done, misalignment of each color will occur in the printing result.

[0026] The expansion and contraction of the film while moving between the respective ejection heads vary depending on the attributes of the film, the drying temperature, the running speed, and the tension. Therefore, even if all the drying temperature, speed, and tension suitable for the coverage regarding the film attributes and the printing design are prepared in advance, the aiming position starting from the standard position of the head will cause misalignment of each color in the printing result, so it is difficult to align the aiming from the first time and multiple trial prints are required.

[0027] As described above, aqueous inkjet printing has become much more complicated compared to gravure printing machines. That is, the printing conditions vary for each printing pattern, and appropriate conditions need to be set each time, and trial printing is required before starting. Similarly, settings are required each time the film type, brand, and thickness are different. These have been obstacles to the automatic operation of an aqueous inkjet printing apparatus that continuously and unmannedly performs printing of a plurality of types with small lot sizes and many varieties, that is, different film attributes and printing designs.

Means for Solving the Problems

[0028] The present invention was created for the purpose of providing an aqueous inkjet printing apparatus capable of automatic operation by solving the above problems.

[0029] That is, the aqueous inkjet printing apparatus capable of automatic operation of the present invention is In an aqueous inkjet printing apparatus in which a film to be printed passes through an ink ejection head portion while being given a constant tension and travels through a hot air drying path, A printing database that stores the attribute data and printing data of the film to be printed, Means for supplying the film to be printed, It has means for storing one or more printing commands including the attribute data, printing data, and printing start of the film to be printed instructed by an operator in a printing execution program. The system is characterized by the following: following the print execution program, it retrieves specified print data from the print database, supplies the specified film to be printed, automatically sets the optimal drying conditions and optimal tension conditions corresponding to the film's attribute data and print data, and automatically sets the ejection position in accordance with the expansion and contraction of the film as it moves between each ejection head, thereby executing all printing.

[0030] Furthermore, the invention described in claim 2 relates to the aforementioned water-based inkjet printing apparatus capable of automatic operation, and uses the coverage of the attributes of the film to be printed and the print design as factors, It is possible to determine the optimal drying conditions, consisting of a drying temperature and running speed that allow for stable running without the film flapping or meandering due to the hot air during hot air drying, while minimizing shrinkage, and the optimal tension conditions that take into account the thermal shrinkage of the film under those drying conditions. An initial preset database that can obtain information on the ejection position, aligned with the expansion and contraction of the film as it moves between each ejection head, under optimal drying conditions and optimal tension conditions, which are determined by the drying temperature and running speed obtained according to the coverage of the film to be printed and the print design. A method for calculating print design coverage from print data. Referencing an initial preset database for each attribute of the film to be printed and coverage information related to the print design, printing speed, drying temperature, tension, Discharge position A print control means that automatically calculates and prints based on these values. It is characterized by having the following features.

[0031] Furthermore, the invention described in claim 3 is characterized in that, in the aforementioned water-based inkjet printing apparatus capable of automatic operation, the attributes of the film to be printed are defined as film type, brand name, thickness, and paper width. [Effects of the Invention]

[0032] According to the aqueous inkjet printing apparatus of the present invention, by providing information on the attributes of the film to be printed and the coverage of the print design in the printing execution program, the printing speed, drying temperature, and tension are automatically calculated even when the coverage, film type, brand, and thickness differ. This allows for stable movement during hot air drying, preventing the film from flapping or meandering due to the hot air, and automatically adjusts to prevent shrinkage. Furthermore, the ejection position is automatically adjusted to match the expansion and contraction of the film as it moves between each ejection head. As a result, multiple types of printing with different film attributes and print designs can be performed automatically and unattended. In other words, according to the present invention, scheduled operation of the aqueous inkjet printing apparatus becomes possible. [Brief explanation of the drawing]

[0033] [Figure 1] Block diagram of the aqueous inkjet printing apparatus of the present invention [Figure 2] The same as above, conceptual diagram of the film supply device. [Figure 3] Conceptual diagram of a water-based inkjet printing device. [Figure 4] Conceptual diagram of a water-based inkjet printing device. [Figure 5] Graph showing the height and depth dimensions of printed pages. [Figure 6] Graph showing left and right dimensions of printed product [Best Mode for Carrying Out the Invention]

[0034] Specific embodiments of the present invention will be described below based on the attached drawings. Figure 3 is a conceptual diagram of the aqueous inkjet printing apparatus that the present invention is based on. In the figure, reference numeral F denotes the film to be printed on, which passes through the ink head unit 20 and travels through the hot air drying path 30 while being subjected to a constant tension. Since the ink head unit 10 is a non-contact type, it is under the same tension conditions as the drying path 30. In the drying path 30, hot air is blown from a nozzle onto the ink surface inside a drying oven to dry it.

[0035] In the present invention, the printing speed, drying temperature, and tension are automatically calculated according to the attributes of the film, and these are automatically adjusted to ensure stable movement during hot air drying so that the film does not flap or meander due to the hot air, and also to prevent shrinkage. The following has been found to be the optimal printing conditions for automatic adjustment.

[0036] In other words, when using water-based inkjet printing on OPP (biaxially oriented polypropylene), a film that generally has low heat resistance, the heat generated during the drying of the water-based ink causes the printed dimensions to expand and contract, resulting in misregistration and product dimensions that deviate significantly from the standard, making printing impossible.

[0037] Since the ink head (printing section) is a non-contact type, it is subject to the same tension conditions as inside a drying oven. However, in general, hot air drying dries the ink surface by applying hot air from a nozzle, so a tension is required that allows the film to run stably without flapping or meandering due to the wind.

[0038] In other words, in water-based inkjet printing, where the film to be printed passes through the inkhead and travels along a hot air drying path while being subjected to a constant tension, it is necessary to consider the heat resistance and other attributes of the film and apply a tension to the film that allows for stable travel so that the film does not flap or meander due to the hot air during hot air drying. Furthermore, it is necessary to adjust the tension and drying temperature to a range in which the film to be printed does not shrink due to the tension and temperature.

[0039] In relation to the above, the inventors of this application have found optimal conditions for water-based inkjet printing even on OPP (biaxially oriented polypropylene), a general-purpose film with low heat resistance, which is used in water-based inkjet printing. By reproducing these optimal conditions, it is possible to maintain a temperature condition that allows the water-based ink to dry sufficiently, while also ensuring a stable running state without fluttering or meandering caused by the hot air in the drying oven. This prevents the OPP (biaxially oriented polypropylene) film with low heat resistance from thermally expanding or contracting, allowing for registration control during printing and ensuring that the product dimensions are within the standard range.

[0040] In this case, the goal is to suppress the thermal expansion and contraction that becomes a problem when using general-purpose film OPP (biaxially oriented polypropylene): heat shrinkage rate at 150°C for 5 minutes: MD (vertical) 8-30%, TD (horizontal) 5-35%, thereby enabling accurate print registration and dimensional reproduction.

[0041] For general-purpose OPP (biaxially oriented polypropylene) film: under the conditions of a heat shrinkage rate of 150°C for 5 minutes, when using MD (vertical) 8-30% and TD (horizontal) 5-35%, and using a drying apparatus with a length of 5.5 m in which the specified water-based ink can be sufficiently dried, by reducing the tension inside the drying oven to 20 N (10 N to 30 N for a width of 760 mm) under the conditions of a drying temperature of 85°C and a speed of 80 m / min, the printed dimensions of the printed film will be within the standard (vertical ±0.2%, horizontal ±0.2%).

[0042] On the other hand, when using high heat-resistant OPP (biaxially oriented polypropylene) with a heat shrinkage rate of 150°C for 5 minutes, MD (vertical) 3-8% and TD (horizontal) 2-6%, the tension inside the drying oven should be reduced to 50N (40N-60N for a width of 760mm).

[0043] With the aforementioned water-based inkjet printer, when using high heat-resistant OPP (biaxially oriented polypropylene) with a heat shrinkage rate of 150°C for 5 minutes, the printed finished dimensions will be within the standard range (vertical ±0.2%, horizontal ±0.2%).

[0044] Based on the above premise, the inventor of the present invention conducted experiments using typical films used in water-based inkjet printing, combining temperature, tension, and heating time. Through these experiments, the inventor discovered the optimal conditions for water-based inkjet printing, considering the temperature required for drying, the tension necessary for stable operation in the drying oven, and the heating time corresponding to the printing speed. By reproducing these optimal conditions, an automated water-based inkjet printing machine can be designed. The details of these experiments are described below.

[0045] <Experiment details> ·Constant temperature and humidifier Yamato Scientific Co., Ltd. Model IG401 Equilibrium Temperature and Humidity Control System (GTHC System) (performance) Temperature and humidity range: +5℃ to +85℃ (87℃ possible) / 40% to 95% Temperature fluctuation: ±1.0℃, Temperature gradient: 5℃, Spatial temperature deviation: 5℃ Humidity fluctuation: ±596 rh, Humidity gradient: 10% rh, Ambient humidity deviation: 1096 rh ·Base material used OPP: Tosei Cello (U-1, 20μm), Futamura Chemical (FOR-AQ, 20μm) Special OPP: Toyobo (P2161, 20μm) PET: Toyobo (E5100, 12μm) ·jig Hanging clip (145mm wide) Weight clips (width 145mm): 350g, 950g, 1,500g Water-based inkjet printing machine: Experimental results with a 760mm width, converted to a sample size of 140mm. *Actual machine 20N = 350g, actual machine 50N = 950g, actual machine 80N = 1,500g specimen Size: Height (film TD direction) 200mm, Width (film MD direction) 140mm ·measurement 300mm JLS1 Grade Metal Ruler + Tokai Sangyo PEAK10x Magnifying Glass (0.1mm increments) • Temperature (each temperature setting + constant humidity of 40%) and heating time 75℃ (4 seconds = 76℃, 11 seconds = 76.5℃, 18 seconds = 77℃) 80℃ (4 seconds = 81℃, 11 seconds = 81.5℃, 18 seconds = 82℃) 85℃ (4 seconds = 86℃, 11 seconds = 86.5℃, 18 seconds = 87℃) The set temperature is adjusted for each heating time to account for the temperature drop in the constant temperature bath. Actual water-based inkjet printing machine: Heating time calculated from speed and drying oven. Drying oven 5.5m, speed 80m / min = 4 seconds, 30m / min = 11 seconds, 0.3m / min = 18 seconds The heating temperature is determined by combining the conditions under which water-based ink dries in the actual machine. *Actual machine speeds of 30m / min = 75℃, 80m / min = 85℃, no actual machine experiments were conducted for 0.3m / min.

[0046] ◎Experimental Method Samples were taken from three locations on the film substrate: both sides and the center, from the horizontal direction (film MD direction). Cut to a size of 200mm (height) x 140mm (width). Make holes with a needle at 100mm intervals both vertically and horizontally in the center of the sample. Before heating, measure both the length and width by 100mm using a metal ruler and magnifying glass (to one decimal place) and record the result. Choose the specified weight for the weight clip. Attach a hanging clip to the top of the specimen and a weight clip to the bottom. Confirm that the constant temperature bath is at the specified temperature (±1°C) and then suspend the specimen in the bath. Close the door of the constant temperature bath and heat for the specified time. After the designated time has elapsed, open the door and remove the sample. Remove the clips from the top and bottom. After heating, measure both the length and width by 100mm using a metal ruler and magnifying glass (to one decimal place) and record. Subtract the difference between the dimensions before heating and the dimensions after heating and record. The graph plots the net dimensions (+ indicates expansion, 1 indicates contraction). Confirm the thermal expansion of each sample.

[0047] <Experimental Results> [Table 1] This indicates the hanging weight that results in a print control range of 0.296 or less. (1) OPP: Tosei Cello: U-1 passes when the vertical temperature is 85° in 4 seconds and the vertical temperature is 75°, 80°, 85°, and horizontal temperature is 85° in 11 seconds, with a tension of 350g. Since printing is done vertically and horizontally simultaneously, low tension is required so that all sides are 350g. (2) OPP: Futamura Chemical: FOR-AQ, like Tosei Cello, requires low tension to be 350g in all cases. (3) Special OPP: Toyobo: P2171 is a film with higher heat resistance than general OPP, so it can be printed in 11 seconds at a vertical temperature of 80°C or 85°C with a tension of 950g. (4) PET: Unlike OPP, Toyobo E5100 is a high heat-resistant film, so it can be printed even at a normal tension of 1,500g.

[0048] <Detailed graph of experimental results> (1) 75℃: OPP vertical heat shrink liner <Tohsero U-1#20> [Table 2]

[0049] (1) 75℃: OPP lateral heat shrinkage <Tohsero U-1#20> [Table 3] (1) At 75℃, water-based ink dries in 11 seconds at a speed of 30m / min on the actual machine, so the printable range is: vertical and horizontal expansion of 0.2% or less. With a tension of 950g for 11 seconds, the vertical tension slightly exceeds the limit; 350g would be acceptable.

[0050] (1) 80℃: OPP vertical heat shrink liner <Tohsero U-1#20> [Table 4]

[0051] (1) 80℃: OPP lateral heat shrinkage <Tohsero U-1#20> [Table 5] (1) At 80℃, the drying limit for water-based ink in the actual machine is 80m / min = 4 seconds, but Printable range: Vertical and horizontal stretching of 0.2% or less With a tension of 950g for 4 seconds, both vertical and horizontal measurements passed.

[0052] (1) 85℃: OPP vertical heat shrink liner <Tohsero U-1#20> [Table 6]

[0053] (1) 85℃: OPP lateral heat shrinkage <Tohsero U-1#20> [Table 7] (1) At 85℃, water-based ink dries in 4 seconds at a speed of 80 m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.2% or less A tension of 950g over 4 seconds slightly exceeds the limit vertically; 350g would be acceptable.

[0054] (2) 75℃: OPP vertical heat shrinkage <Futamura Chemical FOR-AQ#20> [Table 8]

[0055] (2) 75℃: OPP lateral thermal expansion <Futamura Chemical FOR-AQ#20> [Table 9] (2) At 75℃, the water-based ink dries in 11 seconds at a speed of 30m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.2% or less With a tension of 950g for 11 seconds, the vertical tension exceeds the limit; 350g would be acceptable.

[0056] (2) 80℃: OPP vertical heat shrinkage <Futamura Chemical: FOR-AQ#20> [Table 10]

[0057] (2) 80℃: OPP lateral thermal expansion <Futamura Chemical: FOR-AQ#20> [Table 11] (2) At 80℃, the drying limit for water-based ink in the actual machine is 80m / min = 4 seconds, but Printable range: Vertical and horizontal stretching of 0.2% or less With a tension of 950g for 4 seconds, the vertical tension slightly exceeds the limit; 350g would be acceptable.

[0058] (2) 85℃: OPP vertical heat shrinkage <Futamura Chemical: FOR-AQ#20> [Table 12]

[0059] (2) 85℃: OPP lateral thermal expansion <Futamura Chemical: FOR-AQ#20> [Table 13] (2) At 85℃, the water-based ink dries in 4 seconds at a speed of 80 m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.296 or less With a tension of 950g for 4 seconds, the vertical tension slightly exceeds the limit; 350g would be acceptable.

[0060] (3) 75℃: Special OPP vertical heat shrinkage <Toyobo P2171 20μ> [Table 14]

[0061] (3) 75℃: Special OPP transverse heat shrinkage <Toyobo P2171 20μ > [Table 15] (3) At 75℃, the water-based ink dries in 11 seconds at a speed of 30m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.296 or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 11 seconds.

[0062] (3) 80℃: Special OPP vertical heat shrinkage <Toyobo P2171 20μ> [Table 16]

[0063] (3) 80℃: Special OPP transverse heat shrinkage <Toyobo P2171 20μ> [Table 17]

[0064] (3) At 80℃, the drying limit for water-based ink in the actual machine is 80m / min = 4 seconds, but Printable range: Vertical and horizontal stretching of 0.2% or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 4 seconds.

[0065] (3) 85℃: Special OPP vertical heat shrinkage <Toyobo P2171 20μ> [Table 18]

[0066] (3) 85℃: Special OPP transverse heat shrinkage <Toyobo P2171 20μ> [Table 19] (3) At 85℃, the water-based ink dries in 4 seconds at a speed of 80 m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.2% or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 4 seconds.

[0067] (4) 75℃: PET vertical heat shrinkage <Toyobo E5100 12μ> [Table 20]

[0068] (4) 75℃: PET transverse heat shrinkage <Toyobo E5100 12μ> [Table 21]

[0069] (4) At 75℃, the water-based ink dries in 11 seconds at a speed of 30m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.2% or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 11 seconds.

[0070] (4) 80℃: PET vertical heat shrinkage <Toyobo E5100 12μ> [Table 22]

[0071] (4) 80℃: PET transverse thermal expansion <Toyobo E5100 12μ> [Table 23] (4) At 80℃, the drying limit for water-based ink in the actual machine is 80m / min = 4 seconds, but Printable range: Vertical and horizontal stretching of 0.2% or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 4 seconds.

[0072] (4) 85℃: PET vertical heat shrinkage <Toyobo E510012μ> [Table 24]

[0073] (4) 85℃: PET transverse thermal expansion <Toyobo E510012μ> [Table 25] (4) At 85℃, the water-based ink dries in 4 seconds at a speed of 80 m / min in the actual machine. Printable range: Vertical and horizontal stretching of 0.2% or less Because it's a heat-resistant type, it passed both the vertical and horizontal tests even with a tension of 1,500g for 4 seconds.

[0074] One of the features of the present invention is the inclusion of an initial preset function that, as a prerequisite for automatic operation, allows users to input the attributes of the film to be used (film type, brand, thickness, paper width) and the coverage related to the design just before printing. This function automatically sets the optimal drying conditions for water-based ink (drying temperature and speed) and the optimal tension conditions for the substrate being used (the tension of each drive roll for various conditions), making it easy to set the optimal printing conditions.

[0075] In other words, an initial preset database is created containing the optimal drying conditions (drying temperature, speed) derived from the drying condition factors (film type, brand, thickness, paper width, and design coverage) obtained in preliminary tests, and the optimal tension conditions (the tension of each drive roll for each condition) that take into account the thermal shrinkage of the film under those drying conditions. When printing, by selecting the film type, brand, thickness, and paper width from the initial preset settings screen and entering the percentage value for design coverage, the optimal drying temperature and speed, as well as the optimal tension conditions (the tension of each drive roll for each condition) that take into account the thermal shrinkage of the film under those drying conditions, can be automatically and simultaneously set from the first edition without the need for test prints.

[0076] Next, for print registration, the four chromatic colors and the achromatic white are aligned under the optimal printing conditions automatically set by the initial preset during the first printing. In this case, since the initial preset automatically sets the optimal drying and tension conditions, the position where the film is registered when it has heat-shrinkn under those conditions is determined through prior testing and saved in the initial preset database.

[0077] In other words, the optimal drying conditions (drying temperature, speed) obtained from the drying condition factors (film type, brand, thickness, paper width, and design coverage) acquired in preliminary tests, and the optimal tension conditions (pull ratio of each drive roll under various conditions) that take into account the thermal shrinkage of the film under those drying conditions, are added to the initial preset database, along with information on the head ejection position that is properly registered under those conditions. This ensures that the first print run is properly registered without the need for multiple test prints. Since registration can be achieved from the very first print run in the first edition, losses are virtually eliminated, enabling mass production printing. The following is a specific example.

[0078] The initial preset function allows you to easily set optimal printing conditions by first inputting the factors of the substrate to be used (film type, brand, thickness, paper width = example: OPP, Tosei Cello, U-1, #20, 760mm) and the coverage related to the design (example: 4-color coverage = 100%, white 2-color coverage = 140%) just before printing. The function then automatically sets the optimal drying conditions for water-based inks (drying temperature 88℃, speed 80m / min) and the optimal tension conditions for the substrate being used (pull ratio of each drive roll for various conditions: ultra-low pattern = tension 20~25N).

[0079] Figures 3 and 6 are graphs related to print-finished dimensions and print registration. Based on the initial preset database determined through pre-testing, under the conditions shown in Figure 5, for example, the print-finished dimensions would be 0.00 ± 0.1% vertically (as shown in the graph in Figure 3) and 0.30 ± 0.1% horizontally (as shown in the graph in Figure 5). If the horizontal dimensions are not within the standard, the design dimensions are enlarged before printing to bring them within the standard. In other words, this can be addressed with pre-adjustment work, ensuring that the print is completed correctly from the very first print run.

[0080] Print registration is affected by the optimal drying conditions shown in Figures 5 and 6 (drying temperature 88°C, speed 80 m / min) and the optimal tension conditions for the substrate used (pull ratio of each drive roll for various conditions: ultra-weak pattern = tension 20-25N). During drying, the film undergoes thermal shrinkage, which can cause misalignment, especially in the four CMYK colors and the two white colors printed afterward. A database of initial preset registration data, determined through pre-testing, is necessary. This database contains head position information data for all four colors and two white colors (e.g., CMYK 4 colors x 7 heads, white x 2 = position information for all 7 heads) when the registration is correct (e.g., the difference in deviation from the K (black) position (top, bottom, left, right) is within ±0.2 mm of the standard).

[0081] Figure 1 is a block diagram of an automated water-based inkjet printing apparatus according to the present invention. Reference numeral 1 in the figure indicates a print control device that creates and executes a print execution program which stores one or more print commands consisting of attribute data of the film to be printed, print data, and a print start command instructed by an operator, and the print execution program is stored in the storage device 2.

[0082] In the diagram, reference numeral 3 denotes a control panel from which an operator issues print commands to the print control device. Print commands may also be issued from an external terminal 9 via the Internet N. The terminal 9 also serves as a means of receiving abnormality notifications in the event of trouble or errors during unmanned automatic operation.

[0083] In the diagram, reference numeral 5 denotes the print database, which stores print data called according to the print execution program. Here, print data refers to print original data created by the print contractor based on the print design received from the print orderer and information specifying the attributes of the film to be printed, such as film type, brand, thickness, and paper width. This data is created by a wired or wirelessly connected print original creation device 8 and stored in the print database 5 via the print control device of the printing apparatus.

[0084] In the figure, reference numeral 4 denotes the initial preset database. Here, using the attributes of the film to be printed and the coverage of the print design as factors, it is possible to determine the optimal drying conditions consisting of a drying temperature and running speed that allow for stable running without the film flapping or meandering due to the hot air during hot air drying, and that minimize shrinkage, as well as the optimal tension conditions that take into account the thermal shrinkage of the film that changes under those drying conditions. Furthermore, it stores data that allows for the determination of information on the discharge position that is aligned according to the expansion and contraction of the film as it moves between each discharge head, under the optimal drying conditions and optimal tension conditions consisting of the drying temperature and running speed obtained according to the attributes of the film to be printed and the coverage of the print design. For each piece of information regarding the attributes of the film to be printed and the coverage of the print design, this initial preset database is referenced. printing speed, drying temperature, tension, Discharge position This is calculated automatically.

[0085] In the figure, reference numeral 7 denotes a ejection head driven by a control command from the printing execution program, and reference numeral 6 denotes a film supply device that supplies film and runs it at a specified speed, tension, and drying device.

[0086] In the film supply device 6, it is necessary to select and supply multiple types of film F according to control commands from the printing execution program. Although the raw material rolls used for printing can be transported to the printing device by an automated conveyor, all preparation work at the unwinding and winding sections required human intervention. Specifically, tasks such as setting the next raw material roll to be used in the unwinding section and taping the film onto the previous roll, and unwinding the finished printed roll from the winding section, attaching a new paper core, cutting the film, and connecting it to the new paper core were difficult to automate. Furthermore, when the previous roll of raw material was running low, the process of connecting it to a new roll and passing it through the printing press was difficult to automate.

[0087] By the way, while guaranteeing print quality is necessary when accepting printing orders, it has been difficult to automate the process because quality inspection samples must be taken at the time of print completion to check the print quality and guarantee it. Furthermore, while it was necessary to set up the visual inspection machine for each print run, it was difficult to have the visual inspection machine and the inkjet printer work together for unmanned, automated inspection, so it was necessary for an operator to set it up manually.

[0088] Figure 2 is a conceptual diagram of an embodiment of a film supply device for realizing the automation described above, where reference numeral 10 indicates an inkjet printing device on which the film F travels. Reference numeral 12 indicates an automatic transporter 12 that transports a raw roll of film F wound up before printing to a predetermined position, and reference numeral 14 indicates an automatic transporter 14 that transports a printed roll of film F wound up after printing to a predetermined position. In this embodiment, the automatic transporters and the unwinding and winding sections of the inkjet printing device 10 are linked for automatic operation.

[0089] In this embodiment, the unwinding and winding sections use a turret system. When the raw material roll used on axis A is running low, the next raw material roll to be used on axis B (the raw material specified in the printing execution program) is brought close to the set position by the automatic transporter 12 and automatically chucking is performed by the inkjet printing device. This raw material roll has been pre-applied with tape by an operator and is set with the tape-applied part facing upwards. After the inkjet printing device stops, the turret 11 rotates to automatically attach the film F of the A-axis raw material roll to the tape position of the next B-axis raw material roll in the correct position, and then the A-axis film F is automatically cut. The remaining film F of the cut A-axis raw material is automatically wound up. At this time, the automatic transporter 12 is waiting below axis A, and the turret 11 moves automatically to place the remaining A-axis raw material roll onto the automatic transporter. When the raw material roll is removed, the inkjet machine automatically rotates the turret 11 back to its original position. The automated conveyor, carrying the remaining roll of raw material on axis A, moves it to the designated position. At the tape splice of the raw material, the inkjet printing device automatically feeds the material to the winding section, winds it up, and stops. Once these operations are completed without errors, the system automatically enters print start mode.

[0090] This section describes the winding operation after the automatic unwinding process is complete and printing is finished. The winding section also uses a turret system. The printed finished film F is wound onto axis A. A new paper tube (pre-taped by an operator) to be used next is brought to the B axis by an automatic transporter, which approaches the B axis's set position and is automatically chucked by the inkjet printer. The inkjet printer automatically rotates turret 13 to attach the printed finished film from axis A to the tape on the new paper tube on axis B. After that, the blank film F on the printed side of axis A is automatically cut. The remaining blank film F on the printed side of axis A is automatically wound up. At this time, an automatic transporter 14 is waiting below axis A, and turret 13 moves automatically to place the printed finished film from axis A onto the automatic transporter. Once the printed finished film is removed, the inkjet printer automatically rotates turret 13 back to its original position. The automatic transporter carrying the printed finished roll from axis A is then moved to the designated position.

[0091] In this embodiment, when the remaining portion of the raw material roll is nearly depleted, it is connected to a new roll and automatically passed through the printing press. Specifically, the tape connection point between the remaining portion of the raw material roll and the next new roll is detected at the unwinding section, and the inkjet printer automatically runs at a low speed. The printer then detects the position where the tape is wrapped around the winding section and automatically stops. Upon receiving a signal that this automatic operation is complete, the inkjet printer enters automatic printing mode.

[0092] In this embodiment, in order to rationally carry out the process of taking quality inspection samples at the time of print completion to check and guarantee print quality, a system is employed that can guarantee quality if the color difference between the finished print and the color of the printed material is △E=3 or less using a digitized color matching method with a 2D colorimeter. As a result, print samples produced overnight by unmanned automated operation are collected together in a later process the following day. This is done to store and manage the samples that will be kept for the quality assurance period.

[0093] Furthermore, while it is necessary to set up the visual inspection machine for each print run, in this embodiment, the visual inspection machine and the inkjet printing device work together to perform unmanned automatic inspection. That is, the visual inspection machine performs 100% inspection while the inkjet printing device is running. In the present invention, the inkjet printing device is operated automatically and unmanned by the print execution program, and the visual inspection machine is also operated in conjunction with this function.

[0094] Furthermore, the database of initial presets and the print control device for automatic operation described above may be integrated with the printing device, or they may be integrated with a print original creation device used by the printing orderer to create print original data and attribute specification data for the film to be printed, and data may be exchanged with a separate printing device via wired or wireless connections.

[0095] According to the water-based inkjet printing apparatus capable of automatic operation of the present invention, nighttime printing schedules, i.e., printing reservations, are confirmed during daytime shifts. Printing reservations can be made by having the person in charge create a printing execution program in advance in the order in which printing will be done at night. First, on the reservation screen, using the initial preset function, the user selects the film type, brand, thickness, width, and coverage (10% to 150%) as print design information and completes the input. Then, the screen is switched to link the image data. When the image data that has been prepared in advance is selected and clicked on the screen, the name of the image data is written on the reservation screen. After completing these tasks, when the reservation button is pressed, all the information is set in advance in the order of reservation. Occasionally, there are last-minute scheduling issues, and if a nighttime reservation has already been completed or is already made, there is an interrupt function. In the same way, all the input is completed and the "Interrupt" button is pressed, and the reservation becomes the first one to be made.

[0096] Day shift workers, once they have finished all their manual daytime printing tasks, can press the "Start Reservation" button and then the "OK" button. All subsequent print jobs will then enter unattended automatic operation mode and begin automatic operation. If any trouble or error occurs during the process, the machine will remotely transmit information to alert the operator of the abnormality. The machine will remain stopped until it is restored. The operator is responsible for resolving any problems. Once all errors are resolved, the remaining reserved tasks can be restarted. Alternatively, all remaining tasks can be reset. [Explanation of Symbols]

[0097] F Film 1 Printing control device 2 Storage device 3 Control panel 4. Initial Preset Database 5 Printing Database 6. Film feeding device 7 Discharge head 8. Print manuscript preparation device 9 terminals 10. Inkjet printing equipment 11 Turrets 12. Automated transport machines 13 Turrets 14. Automated guided vehicles 20. Inkhead section 30 Hot air drying path

Claims

1. In an aqueous inkjet printing apparatus in which a film to be printed passes through multiple ink ejection heads while being subjected to a constant tension, and is transported via a hot air drying means provided between each ejection head, A print database that stores attribute data and print data of the film to be printed, A print execution program that performs a printing process based on the attribute data of the film and the print data instructed by the operator, A coverage calculation means for calculating the coverage of the print design based on the aforementioned print data, A condition determination means for determining optimal drying conditions, consisting of drying temperature and transport speed, and optimal tension conditions, based on the attribute data of the film and the coverage. An aqueous inkjet printing apparatus comprising a discharge position determining means for determining the discharge position, taking into account the thermal shrinkage of the film that occurs under the aforementioned optimal drying conditions and optimal tension conditions.

2. Further comprising an initial preset database that stores the discharge position, film attribute data, coverage, optimal drying conditions, and optimal tension conditions in association with each other, The aqueous inkjet printing apparatus according to claim 1, characterized in that it obtains the optimal drying conditions, the optimal tension conditions, and the ejection position by referring to the initial preset database based on the attribute data of the film and the coverage.

3. The aqueous inkjet printing apparatus according to claim 1 or 2, characterized in that the attribute data of the film includes film type, brand name, thickness and paper width.

Images