Process for the preparation of a closure bag

Abstract

The application provides a preparation process of a sealing bag, which comprises the following steps: step one, film preparation; step two, printing, which comprises the following steps: step 21, pre-printing preparation, including adjusting a plate roller and a leading wheel of a printing machine, leading the obtained film in step one and color adjusting; step 22, normal printing, opening the plate roller and an ink wheel, transferring the pattern of the plate roller to the surface of the film to prepare a printed film; step 23, drying, drying the printed film through a tunnel type oven, the temperature of the oven is 60-75 DEG C, the pressure of the oven is 1.5-2.1 KPa, the air volume of the oven is 4000-4600 m 3 / h, the oven is slightly negative pressure, and a dried film is obtained; step three, compounding; step four, aging; and step five, bag preparation; in step 22, a plurality of atomizers are arranged on one side of the plate roller, the atomizers are connected with electromagnetic flow valves, and the electromagnetic flow valves are electrically connected to an electric control system of the printing machine. The application can sufficiently reduce the moisture content of the sealing bag product, improve the compounding effect, and enhance the peeling strength and printing effect of the sealing bag product.

Description

Technical Field

[0001] This invention relates to the field of flexible packaging technology, and in particular to a process for preparing a sealing bag. Background Technology

[0002] The standard "Technical Requirements for Gravure and Flexographic Inks for Environmental Labeling Products" (HJ 371-2018) presents new choices and challenges for the printing industry, which primarily uses solvent-based inks. Solvent-based inks contain aromatic compounds such as toluene, benzene, or xylene, which can easily lead to excessive emissions of volatile organic compounds (VOCs), hindering environmentally friendly production.

[0003] Currently, for the production and preparation of flexible packaging, such as resealable bags, there are generally two options for the treatment of volatile organic compounds (VOCs). One is end-of-pipe treatment, which involves the use of RTO or RCO devices for end-of-pipe treatment. This requires a large investment, fails to address the pollution source in the workshop, and is extremely ineffective, time-consuming, and labor-intensive. The other option is to treat the problem at its source by replacing solvent-based inks with water-based inks, thus blocking the source of VOC pollution and ultimately achieving the goal of green production.

[0004] For example, the invention patent CN201911203491.9, "A Low-Speed ​​Continuous Water-Based Ink Printing Process," discloses the following steps: Step 1: Adjusting the printing press: Adjust the operating mode of the printing roller gear and the take-up wheel in the printing press, and set the water-based ink wheel printing mode of the printing press. Then, turn on the blower to preheat for 5-15 minutes. Step 2: Taking the film: Fix the water-based ink tank and printing plate, which have been filled with water-based ink, on the printing press, and adjust the operating speed of the blown film machine and the printing roller gear to take the film onto the printing press. Step 3: Color adjustment: Turn on the printing roller gear and the water-based ink wheel so that the water-based ink wheel contacts the screen roller. After color registration correction, fix the screen roller, printing roller, and press roller. Printing roller; Step 4, Normal printing: Adjust the printing speed, use the lead-out pressure tension regulating valve to adjust the color registration, complete the printing process, and obtain the printed film; The water-based ink in Step 2 is a water-based ink containing 0.15-0.3 wt% fatty alcohol polyoxyethylene ether and 0.1-0.2 wt% rosin; The fatty alcohol polyoxyethylene ether is tetramethyldecynyl glycol polyoxyethylene ether; The rosin is disproportionated rosin; An atomizer is provided on the printing roller in Step 3; The screen roller is a screen roller with a mesh size of 400-500; The printing speed in Step 4 is 27.5 m / min; The initial drying speed of the water-based ink in Step 2 at 25℃ is 70-90 mm / 2 min.

[0005] This invention achieves stable printing by using a screen roller with a specific mesh count, a matching atomizer, and a suitable printing speed. However, the subsequent lamination process in flexible packaging printing, such as sealing bags, has extremely strict requirements for moisture content. Solvent-free lamination even requires the absence of water, which the above solution obviously cannot meet. In addition, the atomizer in the above solution cannot be controlled, and different atomization amounts produce different printing effects for different printing requirements, so the above solution cannot achieve the optimal state.

[0006] In view of this, the inventor has specifically designed a manufacturing process for sealing bags, which leads to this invention. Summary of the Invention

[0007] To solve the above problems, the technical solution of the present invention is as follows:

[0008] A process for preparing a sealing bag includes the following steps:

[0009] Step 1: Film preparation, obtaining raw material thin film through a blown film machine;

[0010] Step 2, printing, includes the following steps:

[0011] Step 21, Pre-press preparation, including adjusting the printing press plate rollers and take-up rollers, taking up the film obtained in Step 1, and color adjustment;

[0012] Step 22: Normal printing. Turn on the printing roller and ink roller to transfer the printing roller pattern to the film surface to obtain the printed film.

[0013] Step 23: Drying. The printed film is dried in a tunnel oven at a temperature of 60-75℃ and a pressure of [missing information].

[0014] 1.5-2.1 kPa, oven air volume 4000-4600 m³ / h 3 / h, the oven is under slight negative pressure to obtain a dry film;

[0015] Step 3: Composite film. The dried film obtained in Step 2 is composited with other protective film layers to obtain a composite film.

[0016] Step 4: Curing. The composite film obtained in Step 3 is cured to obtain a cured film product.

[0017] Step 5: Bag making. Seal the edges of the cured film product obtained in Step 4 to obtain the final sealed bag product.

[0018] In step 22, a number of atomizers are provided on one side of the printing roller, and each of the atomizers is connected to an electromagnetic flow valve, which is electrically connected to the printing press control system.

[0019] Preferably, in step three, the composite method is solvent-free composite.

[0020] Preferably, step three, compounding, includes:

[0021] Step 31: Pre-drying. The dried film obtained in step two is pre-dried by air-cooling drying, while the moisture content of the printed film is monitored by an online moisture detection system.

[0022] Step 32: Solvent-free lamination to obtain a composite film.

[0023] Preferably, in step 31, the online moisture detection system uses a MOSYE near-infrared paper moisture meter, model MS-A-580, manufactured by MOSYE in Germany.

[0024] Preferably, in step 22, the atomizer is a low-pressure fan-shaped atomizing nozzle, model PC2080, manufactured by Guangdong Boyuan Spray Technology Co., Ltd., and the electromagnetic flow valve is a Gems B-Cryo series electromagnetic valve from the United States. The output end of the printing press electrical control system is electrically connected to the input end of the electromagnetic flow valve.

[0025] Preferably, in step 23, the slightly negative pressure environment of the oven is achieved by setting an exhaust device and an exhaust channel. The exhaust device is located at the top of the oven and the air outlet faces the exhaust channel. The exhaust channel connects the inside of the oven and the external environment.

[0026] Preferably, the exhaust duct is equipped with a desiccant, which is a silica gel desiccant.

[0027] The present invention has the following advantages:

[0028] 1. The manufacturing process of the sealing bag described in this invention, by setting multiple atomizers in the printing step and controlling each atomizer individually through an electromagnetic flow valve, can increase or decrease the atomization flow according to different printing requirements, achieve relatively precise control of the water content in the water-based ink printing process, and improve the printing effect of the water-based ink printing process.

[0029] 2. The preparation process of the sealing bag described in this invention uses a tunnel oven to adjust the oven temperature, oven pressure, and oven air volume to adapt to different types of film materials, so as to achieve rapid drying after water-based ink printing, so that the subsequent lamination process can proceed smoothly. At the same time, by establishing a micro-negative pressure environment, the water vapor generated during the drying process can be discharged from the oven in time after the water-based ink printing is completed, preventing water vapor from remaining inside the oven and reaching saturated vapor pressure, so that the environment inside the oven is always conducive to the evaporation of residual water in the water-based ink.

[0030] 3. The preparation process of the sealing bag described in this invention involves pre-drying the printed film and monitoring its moisture content online before the solventless lamination step. This allows the oven parameters in the printing step to be adjusted based on the real-time monitored moisture content, so as to meet the conditions for lamination. Attached Figure Description

[0031] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0032] in:

[0033] Figure 1 This is a process flow diagram of the present invention;

[0034] Figure 2 This is a schematic diagram of the connection structure of the atomizer and the electromagnetic flow valve in this invention;

[0035] Figure 3 This is a schematic diagram illustrating the working principle of the atomizer in this invention.

[0036] Label Explanation:

[0037] 101. Step 1; 102. Step 2; 103. Step 3; 104. Step 4; 105. Step 5; 201. Printing roller; 202. Printing roller gear; 203. Atomizer; 204. Electromagnetic flow valve; 205. Water supply system; 26. Electrical control system. Detailed Implementation

[0038] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0039] Example 1:

[0040] like Figures 1-3 As shown, the present invention provides a process for preparing a sealing bag, comprising the following steps:

[0041] Step 1: Film preparation, obtaining raw material thin film through a blown film machine;

[0042] Step 2, printing, includes the following steps:

[0043] Step 21: Pre-press preparation. Adjust the operating mode of the plate roller gear 202 and the take-up wheel of the printing press 201. Set the printing press to water-ink roller printing mode. Fix the water-ink trough and printing plate to the printing press. Adjust the operating speed of the blown film machine and the plate roller gear 202 to take the film onto the printing press. Turn on the plate roller gear 202 and the water-ink roller so that the water-ink roller contacts the screen roller. After color registration correction, fix the screen roller, plate roller 201 and impression roller.

[0044] Step 22: Normal printing. Turn on the printing roller and ink roller to transfer the printing roller pattern to the film surface, thus obtaining the printed film. Step 23: Drying. The printed film obtained in Step 22 is dried in a tunnel oven at a temperature of 60°C, a pressure of 1.5 kPa, and an airflow of 4000 m³ / h. 3 / h, the oven is under slight negative pressure to obtain a dry film;

[0045] Step 3: Composite film. The dried film obtained in Step 2 is composited with other protective film layers to obtain a composite film.

[0046] Step 4: Curing. The composite film obtained in Step 3 is cured at a temperature of 55°C for 40 hours to obtain the cured film product.

[0047] Step 5: Bag making. The cured film product obtained in Step 4 is heat-sealed to obtain the final sealed bag product.

[0048] In step 22, a number of atomizers 203 are provided on one side of the printing roller. Each of the atomizers 203 is connected to an electromagnetic flow valve 204, which is electrically connected to the printing press control system 206.

[0049] Specifically, such as Figure 2 , 3 As shown, the atomizer 203 uses a low-pressure fan-shaped atomizing nozzle, model PC2080, manufactured by Guangdong Boyuan Spray Technology Co., Ltd., and the electromagnetic flow valve 204 uses a Gems B-Cryo series electromagnetic valve from the USA. The printing press electrical control system 206 is electrically connected to the input terminal of the electromagnetic flow valve 204, as shown. Figure 2 As shown, there are 5 atomizers 203 in this embodiment, and the atomization range of the atomizers 203 is fan-shaped. The water inlet of the electromagnetic flow valve 204 is connected to the same water supply system 205. The water required for atomization is pumped by a water pump. The atomization range of the 5 atomizers 203 evenly covers the length direction of the printing roller. The flow rate of each atomizer 203 is controlled by the electromagnetic flow valve 204. In this embodiment, all atomizers 203 are turned on and the atomization amount of a single atomizer 203 is 300mL / h.

[0050] Preferably, in step three, the composite method is solvent-free composite.

[0051] Preferably, step three, compounding, includes:

[0052] Step 31: Pre-drying. The dried film obtained in step two is pre-dried by air-cooling drying, while the moisture content of the printed film is monitored by an online moisture detection system.

[0053] Specifically, in step 31, the pre-drying process uses a direct air-cooled drying method with a cold fan, and the online moisture detection system uses a MOSYE near-infrared paper moisture meter manufactured by Moss in Germany, model MS-A-580.

[0054] Step 32: Solvent-free composite.

[0055] Preferably, in step 23, the slightly negative pressure environment of the oven is achieved by setting up an exhaust device and an exhaust duct. The exhaust device is located at the top of the oven with its air outlet facing the exhaust duct. The exhaust duct connects the inside of the oven to the external environment, and the exhaust volume of the exhaust device is slightly greater than 4000 m³ / h. 3 / h, specifically set to 4020m 3 / h This creates a slightly negative pressure environment inside the oven, thereby expelling residual moisture from the oven.

[0056] Preferably, a desiccant is installed in the exhaust duct. The desiccant is a silica gel desiccant, which absorbs the moisture discharged from the oven and prevents the air circulating back into the oven from carrying moisture, thereby improving the drying effect of the oven.

[0057] Example 2:

[0058] The difference from Example 1 is that in step 23, drying, the printed film obtained in step 22 is dried in a tunnel oven at a temperature of 75°C, a pressure of 2.1 kPa, and an air volume of 4600 m³ / h. 3 / h, the oven is under slight negative pressure to obtain a dried film.

[0059] Example 3:

[0060] The difference from Example 1 is that in step 23, drying, the printed film obtained in step 22 is dried in a tunnel oven at a temperature of 70°C, a pressure of 1.8 kPa, and an air volume of 4300 m³ / h. 3 / h, the oven is under slight negative pressure to obtain a dried film.

[0061] Example 4:

[0062] The difference from Example 1 is that in step 23, drying, the exhaust volume of the oven exhaust device is 4000m³. 3 / h, no micro-negative pressure environment.

[0063] Example 5:

[0064] The difference from Example 1 is that in step 23, drying, the exhaust volume of the oven exhaust device is 3980 m³ / h. 3 / h, no micro-negative pressure environment.

[0065] Example 6:

[0066] The difference from Example 1 is that there are 5 atomizers 203, and the atomization volume of each atomizer 203 is adjusted to 200mL / h.

[0067] Example 7:

[0068] The difference from Example 1 is that there are 5 atomizers 203 in total, with the middle 3 atomizers 203 being activated, and the atomization volume of each atomizer 203 being adjusted to 300mL / h.

[0069] Example 8:

[0070] The difference from Example 1 is that the pre-drying process and the online moisture content monitoring process in step 31 are omitted, and the atomization volume of a single atomizer 203 is 300 mL / h.

[0071] Example 9:

[0072] The difference from Example 1 is that the pre-drying process and the online moisture content monitoring process in step 31 are omitted, and the atomization volume of a single atomizer 203 is 150 mL / h.

[0073] Performance evaluation:

[0074] According to the preparation process of the sealing bag described in Examples 1 to 10, the same pattern is printed on the sealing bag film, wherein the extension length of the pattern along the axial direction of the printing roller is less than the atomization range of the three middle atomizers.

[0075] Evaluation indicators:

[0076] Image and text clarity is categorized as follows: extremely high clarity (3 points); high clarity (2 points); average clarity (1 point); and poor clarity (0 points). Calculate the average score and fill it in the table.

[0077] Coloring rate: 3 points for extremely high coloring rate; 2 points for relatively high coloring rate; 1 point for average coloring rate; 0 points for poor coloring rate. Calculate the average score and fill it in the table.

[0078] Peel strength: The final sealed bag product is cut into 15mm×200mm test strips, and the peel strength of the product is tested on a BLD computer-controlled peel tester. The unit of peel strength is N / 15mm.

[0079] Table 1 Performance Test Results

[0080] Examples Figure clarity Coloring rate Peeling strength (N / 15mm) Example 1 3.0 3.0 0.78 Example 2 3.0 3.0 0.82 Example 3 2.0 2.0 0.80 Example 4 1.5 1.7 0.62 Example 5 1.0 1.4 0.52 Example 6 2.8 2.7 0.80 Example 7 2.8 2.7 0.78 Example 8 1.9 2.0 0.26 Example 9 2.4 1.9 0.32

[0081] As shown in Examples 1-3, the air volume, pressure, and temperature of the drying oven are all within a range of 4600 m³ / h. 3 At 2.1 kPa and 75°C, the final sealed bag composite film product achieves the best performance. At this time, the moisture content is thoroughly dried in the oven and preheated before lamination, so that the final peel strength of the product also reaches the best.

[0082] As can be seen from Examples 4 and 5, the drying effect of the oven without a micro-negative pressure environment on the sealing bag composite film product is reduced. This is because water vapor gradually remains in the oven, which prevents the printed film obtained in step 22 from being completely dried in the oven. The moisture is partially removed in the preheating stage of step 3, but some moisture is still present in the final product, resulting in a poor composite effect and reduced peel strength.

[0083] As can be seen from Examples 6 and 7, the number and flow rate of atomizers can be controlled according to different printing ranges, and peel strength, image clarity and coloring rate close to the optimal performance can be achieved. At the same time, reducing the amount of atomized water is beneficial to improving the drying effect of the subsequent drying process, reducing the impact of water content in water-based ink on solvent-free lamination, promoting the application of water-based ink, and contributing to environmental protection.

[0084] As can be seen from Examples 8 and 9, without pre-drying, the atomized water sprayed to enhance the water-based ink printing effect has a significant impact on the final lamination of the sealing bag composite film product. Excessive moisture content greatly interferes with solvent-free lamination, and the lamination strength even drops to 0.26N / 15mm and 0.32N / 15mm, which does not meet the requirements. Therefore, the preheating process and online monitoring of moisture content have a promoting effect on the smooth lamination process and the improvement of product peel strength.

[0085] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A process for preparing a sealing bag, characterized in that, Includes the following steps: Step 1: Film preparation, obtaining raw material thin film through a blown film machine; Step 2, printing, includes the following steps: Step 21, Pre-press preparation, including adjusting the printing press plate rollers and take-up rollers, taking up the film obtained in Step 1, and color adjustment; Step 22: Normal printing. Turn on the printing roller and ink roller to transfer the printing roller pattern to the film surface to obtain the printed film. In step 22, the atomizer uses a low-pressure fan-shaped atomizing nozzle, model PC2080, manufactured by Guangdong Boyuan Spray Technology Co., Ltd., and the electromagnetic flow valve uses a Gems B-Cryo series electromagnetic valve from the United States. The output end of the printing press electrical control system is electrically connected to the input end of the electromagnetic flow valve. Step 23, Drying: The printed film obtained in step 22 is dried in a tunnel oven at a temperature of 60-75℃, a pressure of 1.5-2.1 kPa, an air volume of 4000-4600 m³ / h, and a slight negative pressure to obtain a dried film. In step 23, the oven's micro-negative pressure environment is achieved by setting up an exhaust device and an exhaust channel. The exhaust device is located at the top of the oven and its air outlet faces the exhaust channel. The exhaust channel connects the inside of the oven with the external environment. The exhaust duct is equipped with a desiccant, which is a silica gel desiccant pack. Step 3: Composite film. The dried film obtained in Step 2 is composited with other protective film layers to obtain a composite film. Step 31: Pre-drying. The dried film obtained in step two is pre-dried by direct air-cooling drying with a cooling fan, while the moisture content of the printed film is monitored by an online moisture detection system. Step 32: Solvent-free lamination to obtain a composite film; Step 4: Curing. The composite film obtained in Step 3 is cured to obtain a cured film product. Step 5: Bag making. Seal the edges of the cured film product obtained in Step 4 to obtain the final sealed bag product. In step 22, five atomizers are provided on one side of the printing roller, and the atomization range of the atomizers is fan-shaped. The atomization range of the five atomizers evenly covers the length direction of the printing roller, and each atomizer is connected to an electromagnetic flow valve. The flow rate of each atomizer is controlled by the electromagnetic flow valve, which is electrically connected to the printing press control system.

2. The manufacturing process of a sealing bag according to claim 1, characterized in that, In step 31, the online moisture detection system uses a MOSYE near-infrared paper moisture meter, model MS-A-580, manufactured by MOSYE in Germany.

Images