Production process of plastic packaging bag easy to tear

Abstract

The invention provides a production process of an easy-to-tear plastic packaging bag, and belongs to the technical field of easy-to-tear plastic packaging bags, the production process of the easy-to-tear plastic packaging bag comprises the following steps: preparing three layers of materials, namely an upper base material, a lower base material and a tearable induction layer; the tearable induction layer is unreeled and enters an online punching station for punching after tension control; the upper base material, the induction layer and the lower base material are overlapped in sequence and then enter a hot-pressing compounding unit to be subjected to hot-pressing compounding; after being cooled and shaped, the compounded three-layer membrane material enters a laser scribing station to be subjected to laser scribing; the punched and marked composite film material is fed into a bag making unit, a single packaging bag is formed after heat sealing and cutting, and guide lines on the two sides of a bag body are parallel to a sealing opening; the problems that in existing easy-to-tear plastic packaging bag production, easy-to-tear strips are additionally pasted or notches are mechanically punched, the material and labor cost is increased, secondary machining is needed in a production line, and the efficiency is low can be solved.

Description

Technical Field

[0001] This invention belongs to the technical field of easy-tear plastic packaging bags, and more specifically, relates to a production process for easy-tear plastic packaging bags. Background Technology

[0002] Plastic packaging bags are bags made primarily of plastics (such as polyethylene, polypropylene, polyester, nylon, etc.) and are widely used for packaging food, daily necessities, pharmaceuticals, cosmetics, electronic products, and industrial products. Their production process typically includes multiple stages such as film blowing, printing, slitting, bag making, sealing, and rewinding. The tear propagation path of ordinary PE / PP films is uncontrollable and easily deviates from the intended direction, resulting in uneven tears, affecting user experience, and even causing leakage of contents. Existing "easy-tear" solutions mostly involve additional easy-tear strips or mechanical punching, increasing material and labor costs and requiring secondary processing, reducing production efficiency. If the cut material needs to be manually stretched and flattened, wrinkles are likely to occur during rewinding. Rewinding before the ink is dry after printing can lead to smeared patterns, affecting automation and product quality. Hot-pressing flattening equipment struggles to achieve precise temperature and pressure control, and sealing equipment lacks flattening functions, easily causing sealing wrinkles or failures. Edge material accumulation during melting and cutting requires manual cleaning, easily causing contamination. Summary of the Invention

[0003] In view of this, the present invention provides a production process for easy-tear plastic packaging bags, which can solve the problems of existing easy-tear plastic packaging bag production, which mostly involves attaching easy-tear strips or mechanically punching notches, increasing material and labor costs, and requiring secondary processing on the production line, resulting in low efficiency.

[0004] This invention is implemented as follows: This invention provides a manufacturing process for easy-tear plastic packaging bags, wherein the specific steps include: S10: Prepare three layers of material, namely the upper substrate, the lower substrate, and the tear-inducing layer; S20: The tearable induction layer is unwound and, after tension control, enters the online punching station for punching; S30: The upper substrate, the inducing layer and the lower substrate are stacked in sequence and then put into the hot pressing composite unit for hot pressing composite; S40: After the composite three-layer film material is cooled and shaped, it enters the laser scribing station for laser scribing. S50: The perforated and marked composite film material is fed into the bag making unit, and after heat sealing and cutting, it forms a single packaging bag. The guide lines on both sides of the bag are parallel to the seal.

[0005] Based on the above technical solution, the production process of the easy-tear plastic packaging bag of the present invention can be further improved as follows: The upper substrate and the lower substrate are both made of PE or PP film with a thickness of 20-80 μm; the tear-inducing layer is made of PET, PA or modified PE film with a thickness of 5-25 μm; the thickness of the tear-inducing layer is less than 1 / 2 of the thickness of the upper substrate or the lower substrate, and the total thickness of the upper substrate, the lower substrate and the tear-inducing layer after lamination is 60-90 μm; the upper substrate and the lower substrate are corona-treated on the side closest to the tear-inducing layer.

[0006] Furthermore, during the hot-pressing process of sequentially stacking the upper substrate, the inducing layer, and the lower substrate into the hot-pressing composite unit, a bump array is set on the surface of the hot-pressing roller, with a bump diameter of 0.3~1mm and a distribution density of 5~20 points / cm²; the hot-pressing temperature is 90~130℃, the pressure is 0.1~0.5MPa, and the time is 0.1~0.5s; only the area corresponding to the bumps forms a weak point bond, while the remaining areas remain loosely bonded; The upper roller of the hot press roller is made of φ320mm steel roller with hard chrome plating on the surface and 6-head spiral heat-conducting oil circulation in the inner cavity; the lower roller is made of φ320mm silicone rubber roller with a thickness of 20mm; the roller surface width is set to 650mm and the effective composite area is 550mm; hydraulic cylinders are configured at both ends, and the pressure is linearly adjustable from 0 to 1.0MPa.

[0007] Furthermore, the specific steps of sequentially stacking the upper substrate, the inducing layer, and the lower substrate before hot-pressing them into the hot-pressing composite unit include: The first step is to stack the upper substrate, the induction layer, and the lower substrate in sequence to form a three-layer composite blank. The second step is to set the steel roller temperature to 90-130℃, the rubber roller temperature to ≤45℃, and the linear speed to 80 mm / min⁻¹. The third step is to adjust the linear pressure to 25~40 Nmm⁻¹, so that the local pressure at the protrusion is 3~5 MPa; In the fourth step, in the bumped area, the PE surface layer of the upper substrate and the lower substrate melts to a depth of 5~8µm and forms a dotted heat seal with the TI surface; the non-bumped area remains unbonded or peelable. The fifth step is to immediately pass the film through a 25°C cooling roller after it exits the pressure zone to reduce the surface temperature of the composite film to ≤45°C, thus completing the shaping process.

[0008] Furthermore, in the specific steps of laser scribing after the composite three-layer film material is cooled and shaped, a CO2 or UV laser with a power of 10~50W is used to scribble straight guide lines on both sides of the film material at a distance of 5~15mm from the bag seal; the scribing depth is 10~30% of the total thickness of the film material, and the scribing speed is 50~200m / min; The cooling and shaping process is carried out using a main cooling roller and an auxiliary cooling roller. The main cooling roller is a φ300mm double-layer spiral flow channel steel roller, and the auxiliary cooling roller is a φ150mm silicone rubber roller. The cooling is carried out by circulating ethylene glycol-water at 5℃, with a volume ratio of ethylene glycol to water of 3:7. The specific steps for cooling and shaping the composite three-layer membrane are as follows: The first step is to immediately introduce the hot-pressed composite three-layer film into the cooling zone, where it will remain for 0.4 to 0.6 seconds. The second step is to use a vortex fan to assist in heat dissipation on the non-contact surface, ensuring that the film surface temperature is ≤25℃ before leaving the cooling zone; The third step involves using an infrared thermometer to provide closed-loop feedback to the frequency converter pump, enabling real-time adjustment of the roller temperature. The fourth step is to install an electrostatic eliminator at the outlet of the cooling section to prevent dust from adhering and causing laser energy scattering.

[0009] Furthermore, the specific steps for the composite three-layer film material to undergo laser scribing after cooling and shaping include: The first step is to introduce the cooled three-layer composite film into the laser scribing station, maintaining a tension of 25±2N. The second step is to set the laser power to 20-35W, the scanning speed to 1000-2000 mms⁻¹, and the pulse duty cycle to 40-60%. The third step involves drawing two straight guide lines along the machine direction using the Galvo scanning head, with a line width of 120±20μm. The fourth step involves using a coaxial vision system to collect the depth of the scribing groove in real time. When the depth deviation exceeds ±3μm, the power is automatically adjusted by ±2% or the speed by ±5%. The fifth step is to immediately blow and cool the groove after marking it, so that the surface temperature of the groove is ≤40℃, and then put it into the storage rack.

[0010] Furthermore, the specific steps of feeding the perforated and marked composite film material into the bag-making unit, and forming individual packaging bags after heat sealing and cutting, with the guide lines on both sides of the bag body parallel to the seal, include: Step 1, Material Storage and Transition: The swing roller storage rack supplies film to the bag making machine with a tension of 25±2N and a linear speed of 120m / min, ensuring 15s continuous material supply during zero-speed roll change; The second step is to correct and position the deviation: the edge control accuracy of EPC is ±0.2mm, and the bag is centered in the width direction; the guide line is 8mm away from the seal, and the CCD detection offset is ≤0.1mm; Step 3, longitudinal sealing: servo traction speed = film linear speed, heat sealing knife temperature 125±3℃, pressure 0.3MPa, sealing width 10mm, cooling pressure roller ≤30℃.

[0011] Step 4, horizontal sealing of top and bottom: double set of rotating horizontal sealing blades, temperature 130±2℃, pressure 0.35MPa, sealing time 0.25s, cooling blade ≤35℃; Step 5, guide line alignment: the parallelism between the center line of the horizontal sealing knife and the laser guide line is ≤0.2mm, and the servo phase adjustment step is 0.1°; Step 6, online cutting: The servo flying shear is synchronized with the film speed, the cutting speed ratio is 1:1, the straightness of the cut is ≤0.1mm, and there is no stringing; Step 7, Finished Product Output: The vacuum conveyor belt delivers the single bags at 120m / min, counts and stacks them, and the parallelism deviation between the guide lines on both sides of the bag and the seal is ≤0.3mm; Furthermore, in the specific step of unwinding the tearable induction layer, an ultrasonic sensor is used to monitor the roll diameter in real time, and the target tension range is 20±2N. During the online drilling process after tension control, a φ50mm exhaust port is set at the bottom of the equipment, with a wind speed of 20ms⁻¹. It is equipped with a 3-stage filter, and the filter element is automatically replaced when the differential pressure sensor reaches >300Pa.

[0012] Furthermore, in the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, CO2 or UV is used for punching to form an intermittent micropore array on the surface of the inducing layer; the micropore diameter is 50~300μm, the hole spacing is 0.5~2mm, and they are arranged linearly or staggered; the punching speed is 50~200m / min. When using a CO2 laser, the wavelength is set to 10.6 μm, the rated power is 30 W, and the TEM... 00 The beam quality M² is less than 1.2; a ZnSe lens with a focal length of 63mm is used, and the theoretical spot diameter after focusing is approximately 80μm; the coaxial red indicator light is less than 1mW for easy adjustment; the drilling process is performed by scanning line by line in a staggered hexagonal array with a line spacing of 0.87mm and a phase offset of 0.5mm between adjacent lines to ensure uniform tearing stress; the drilling process uses a coaxial CCD to acquire the hole shape, and the image algorithm extracts the hole area A; when |A−A0| / A0>5% (A0 is the calibration value), the laser power is automatically adjusted by ±2% to ensure that the hole diameter CV value is less than 3%.

[0013] Furthermore, in the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, a mechanical micro needle roller is used for punching. The outer diameter of the needle roller is set to 120mm, the needle length is set to 250μm, the tip angle is 30°, the material is tungsten carbide, and the hardness is >1800HV. The pressing depth is adjusted to match the thickness of the substrate. The surface of the needle roller is coated with 0.5μm DLC to reduce adhesion. The speed of the needle roller is kept at a tangential speed of 1:1 with the film line speed to reduce tailing deformation. The needle roller is equipped with an anti-static copper wire brush on the side, with a bristle diameter of 0.1mm and a speed of 1500rpm, to guide PET debris into the dust collection box.

[0014] Compared with existing technologies, the beneficial effects of the easy-tear plastic packaging bag production process provided by this invention are: The upper and lower substrates are selected as 20~80μm PE / PP, and the induction layer is made of 5~25μm PET / PA / m-PE with a thickness <1 / 2 of the substrate. The total thickness of the composite is compressed to 60~90μm, which maintains stiffness and reduces tear resistance. The corona surface faces the induction layer and has a surface tension ≥48dyncm⁻¹, which provides an activated surface for subsequent dot heat sealing.

[0015] 20±2N constant tension + EPC±0.2mm ensures a wrinkle-free and unbiased film surface; ultrasonic roll diameter feedforward ensures zero-speed film splicing during roll changes, allowing the production line to operate without interruption.

[0016] Laser mode: 30W CO2, 80μm focal spot, misaligned hexagonal scanning, aperture 50~300μm, aperture spacing 0.5~2mm, aperture area occupancy 3~8%, tear force pre-reduction 25~35%; coaxial CCD closed loop ensures aperture CV <3%, ensuring uniform tear stress.

[0017] Microneedle mode: 1800HV tungsten carbide needle, DLC coating, 1:1 cutting speed, consistent hole shape, no trailing; side copper brush + negative pressure dust collection to avoid debris contamination of the composite surface.

[0018] A φ320mm steel roller (90~130℃) and a rubber roller (≤45℃) form an 8% convex contact area with a local pressure of 3~5MPa. Only 5~8μm of surface layer melts, achieving a "point-like weak adhesion" area ratio of 6~10%. The peel strength is 0.5~0.8N / 15mm, which not only ensures that the bag does not delaminate, but also reduces the tearing force by 30~40%.

[0019] The 25℃ cooling roller cools the film surface to ≤45℃ within 0.4~0.6s, ensuring that the pore shape remains unchanged after setting, there is no backflow of adhesive layer, and the induction layer remains continuous.

[0020] With 5℃ ethylene glycol-water circulation and vortex air assistance, the membrane surface temperature is ≤25℃ when entering the scribing zone, and the HAZ shrinks to ≤120μm.

[0021] 20~35W CO2, 1000~2000mms⁻¹Galvo scanning, etch guide lines with 10~30% residual thickness at 5~15mm from the seal, line width 120±20μm; coaxial vision ±3μm closed loop, depth CV≤4%, tear path straightness≤0.5mm.

[0022] The storage rack has a tension of 25N and a continuous film supply of 120m / min. Zero-speed roll changing has a 15s buffer, and the production line does not stop.

[0023] EPC ±0.2mm + CCD guide line offset ≤0.1mm, ensuring that the parallelism between the subsequent longitudinal / transverse sealing knife and the guide line is ≤0.2mm.

[0024] Longitudinal seal 125±3℃, 0.3MPa, transverse seal 130±2℃, 0.35MPa, 0.25s, cooling blade ≤35℃, sealing strength ≥25N / 15mmyet does not interfere with tearing.

[0025] The servo flying shear is synchronized with the film speed at a 1:1 ratio, with a cut straightness of ≤0.1mm and no stringing; the parallelism deviation between the guide lines on both sides of the finished bag and the seal is ≤0.3mm, and when the user tears along the guide lines, the tear is straight, without debris, and the contents do not splash.

[0026] Different thicknesses of film materials are selected to form the base of the packaging bag. The outer and bottom substrates are made of PE or PP film with a thickness between 20 and 80 μm, serving as the upper and lower substrates of the packaging bag. The middle layer is a tear-inducing layer, usually made of PET, PA, or modified PE film with a thickness of 5–25 μm, placed between the upper and lower substrates as an easily tearable intermediary layer.

[0027] The tearable induction layer is unwound, and tension control ensures the material maintains a stable shape during production, preventing deformation. The tension control range is 20±2 N, and the roll diameter is monitored in real time using an ultrasonic sensor to ensure consistency of material in each roll.

[0028] The three layers of material are laminated using hot press rollers. The hot pressing conditions are set as follows: temperature 90–130℃, pressure 0.1–0.5MPa, and lamination time 0.1–0.5 seconds. The hot press rollers, with their surface array of raised dots, form a dotted weak bond, ensuring a non-firm adhesion between the middle layer and the upper and lower substrates, thus achieving an easy-tear effect.

[0029] After cooling and setting, the film material enters the laser scribing station. A CO2 or UV laser is used for scribing, with the power set between 20–35W, a scanning speed of 1,000–2,000 mm / s, and a scribing depth of 10–30% of the total film thickness. The purpose of laser scribing is to create guide lines on both sides of the film material, 5–15 mm from the bag seal.

[0030] The laser-marked composite film is fed into the bag-making unit for heat sealing. The longitudinal heat sealing temperature is set at 125±3℃, and the seal width is 10mm. The horizontal sealing of the top and bottom uses a double-set rotating horizontal sealing blade, with a sealing temperature of 130±2℃ and a sealing time of 0.25 seconds. Afterward, a servo flying shear is used for online cutting to ensure that the straightness of the cut is ≤0.1mm and there is no stringing.

[0031] The membrane material is cooled by cooling rollers, employing a combination of double-layer spiral flow channel steel rollers and silicone rubber rollers, using a 5°C ethylene glycol-water circulating liquid. Auxiliary heat dissipation is achieved by a vortex fan, ensuring the membrane surface temperature does not exceed 25°C.

[0032] Drilling can be performed using a CO2 laser, with a hole diameter range of 50–300 μm and a hole spacing of 0.5–2 mm, ensuring consistent hole diameter and spacing for improved tearability. Alternatively, drilling can be performed using a tungsten carbide needle roller to ensure hole precision and uniformity.

[0033] Both the upper and lower substrates are PE or PP films with a thickness between 20 and 80 μm. The thickness of the middle induction layer film is less than half that of the upper and lower substrates, ensuring that the final composite film thickness is 60–90 μm.

[0034] The upper roller is a hard chrome-plated steel roller, and the lower roller is a silicone rubber roller, ensuring a more stable hot-pressing composite effect.

[0035] Real-time feedback from the laser system and visual monitoring system ensures the accuracy of marking and punching, further optimizing the tear-off effect. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the production process of an easy-tear plastic packaging bag. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0038] like Figure 1 The diagram shows the operation flow chart of an easy-tear plastic packaging bag production process provided by the present invention. The specific steps in the diagram include: S10: Prepare three layers of material, namely the upper substrate, the lower substrate, and the tear-inducing layer; S20: The tearable induction layer is unwound and, after tension control, enters the online punching station for punching; S30: The upper substrate, the inducing layer and the lower substrate are stacked in sequence and then put into the hot pressing composite unit for hot pressing composite; S40: After the composite three-layer film material is cooled and shaped, it enters the laser scribing station for laser scribing. S50: The perforated and marked composite film material is fed into the bag making unit, and after heat sealing and cutting, it forms a single packaging bag. The guide lines on both sides of the bag are parallel to the seal.

[0039] In the above technical solution, both the upper substrate and the lower substrate are made of PE or PP film with a thickness of 20~80μm; the tear-inducing layer is made of PET, PA or modified PE film with a thickness of 5~25μm; the thickness of the tear-inducing layer is less than 1 / 2 of the thickness of the upper substrate or the lower substrate, and the total thickness of the upper substrate, the lower substrate and the tear-inducing layer after lamination is 60~90μm; the side of the upper substrate and the lower substrate close to the tear-inducing layer is subjected to corona treatment.

[0040] Furthermore, in the above technical solution, after the upper substrate, the inducing layer, and the lower substrate are sequentially stacked and then placed into the hot-pressing composite unit for hot-pressing composite process, a bump array is set on the surface of the hot-pressing roller, with a bump diameter of 0.3~1mm and a distribution density of 5~20 points / cm²; the hot-pressing temperature is 90~130℃, the pressure is 0.1~0.5MPa, and the time is 0.1~0.5s; only the area corresponding to the bumps forms a weak point bond, while the remaining areas remain loosely bonded; The upper roller of the hot press roller is made of φ320mm steel roller with hard chrome plating on the surface and 6-head spiral heat-conducting oil circulation in the inner cavity; the lower roller is made of φ320mm silicone rubber roller with a thickness of 20mm; the roller surface width is set to 650mm and the effective composite area is 550mm; hydraulic cylinders are configured at both ends, and the pressure is linearly adjustable from 0 to 1.0MPa.

[0041] Furthermore, in the above technical solution, the specific steps of sequentially stacking the upper substrate, the inducing layer, and the lower substrate before hot-pressing composite unit include: The first step is to stack the upper substrate, the induction layer, and the lower substrate in sequence to form a three-layer composite blank. The second step is to set the steel roller temperature to 90-130℃, the rubber roller temperature to ≤45℃, and the linear speed to 80 mm / min⁻¹. The third step is to adjust the linear pressure to 25~40 Nmm⁻¹, so that the local pressure at the protrusion is 3~5 MPa; In the fourth step, in the bumped area, the PE surface layer of the upper substrate and the lower substrate melts to a depth of 5~8µm and forms a dotted heat seal with the TI surface; the non-bumped area remains unbonded or peelable. The fifth step is to immediately pass the film through a 25°C cooling roller after it exits the pressure zone to reduce the surface temperature of the composite film to ≤45°C, thus completing the shaping process.

[0042] Furthermore, in the above technical solution, in the specific steps of laser scribing after the composite three-layer film material is cooled and shaped, a CO2 or UV laser with a power of 10~50W is used to scribble straight guide lines on both sides of the film material at a distance of 5~15mm from the bag seal; the scribing depth is 10~30% of the total thickness of the film material, and the scribing speed is 50~200m / min; Cooling and shaping are carried out using a main cooling roller and an auxiliary cooling roller. The main cooling roller is a φ300mm double-layer spiral flow channel steel roller, and the auxiliary cooling roller is a φ150mm silicone rubber roller. 5℃ ethylene glycol-water is used for circulating cooling, and the volume ratio of ethylene glycol to water is 3:7. The specific steps for cooling and shaping the composite three-layer membrane are as follows: The first step is to immediately introduce the hot-pressed composite three-layer film into the cooling zone, where it will remain for 0.4 to 0.6 seconds. The second step is to use a vortex fan to assist in heat dissipation on the non-contact surface, ensuring that the film surface temperature is ≤25℃ before leaving the cooling zone; The third step involves using an infrared thermometer to provide closed-loop feedback to the frequency converter pump, enabling real-time adjustment of the roller temperature. The fourth step is to install an electrostatic eliminator at the outlet of the cooling section to prevent dust from adhering and causing laser energy scattering.

[0043] Furthermore, in the above technical solution, the specific steps for the composite three-layer film material to undergo laser scribing after cooling and shaping include: The first step is to introduce the cooled three-layer composite film into the laser scribing station, maintaining a tension of 25±2N. The second step is to set the laser power to 20-35W, the scanning speed to 1000-2000 mms⁻¹, and the pulse duty cycle to 40-60%. The third step involves drawing two straight guide lines along the machine direction using the Galvo scanning head, with a line width of 120±20μm. The fourth step involves using a coaxial vision system to collect the depth of the scribing groove in real time. When the depth deviation exceeds ±3μm, the power is automatically adjusted by ±2% or the speed by ±5%. The fifth step is to immediately blow and cool the groove after marking it, so that the surface temperature of the groove is ≤40℃, and then put it into the storage rack.

[0044] Furthermore, in the above technical solution, the specific steps of feeding the perforated and marked composite film material into the bag-making unit, and forming individual packaging bags after heat sealing and cutting, with the guide lines on both sides of the bag body parallel to the seal, include: Step 1, Material Storage and Transition: The swing roller storage rack supplies film to the bag making machine with a tension of 25±2N and a linear speed of 120m / min, ensuring 15s continuous material supply during zero-speed roll change; The second step is to correct and position the deviation: the edge control accuracy of EPC is ±0.2mm, and the bag is centered in the width direction; the guide line is 8mm away from the seal, and the CCD detection offset is ≤0.1mm; Step 3, longitudinal sealing: servo traction speed = film linear speed, heat sealing knife temperature 125±3℃, pressure 0.3MPa, sealing width 10mm, cooling pressure roller ≤30℃.

[0045] Step 4, horizontal sealing of top and bottom: double set of rotating horizontal sealing blades, temperature 130±2℃, pressure 0.35MPa, sealing time 0.25s, cooling blade ≤35℃; Step 5, guide line alignment: the parallelism between the center line of the horizontal sealing knife and the laser guide line is ≤0.2mm, and the servo phase adjustment step is 0.1°; Step 6, online cutting: The servo flying shear is synchronized with the film speed, the cutting speed ratio is 1:1, the straightness of the cut is ≤0.1mm, and there is no stringing; Step 7, Finished Product Output: The vacuum conveyor belt delivers the single bags at 120m / min, counts and stacks them, and the parallelism deviation between the guide lines on both sides of the bag and the seal is ≤0.3mm; Furthermore, in the above technical solution, in the specific steps of unwinding the tearable induction layer, an ultrasonic sensor is used to monitor the roll diameter in real time, and the target tension range is 20±2N. After tension control, the equipment enters the online drilling station for drilling. A φ50mm exhaust port is set at the bottom of the equipment, with a wind speed of 20ms⁻¹. It is equipped with a 3-stage filter and automatically alarms and replaces the filter element when the differential pressure sensor reaches >300Pa.

[0046] Furthermore, in the above technical solution, in the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, CO2 or UV is used for punching to form an intermittent micropore array on the surface of the inducing layer; the micropore diameter is 50~300μm, the hole spacing is 0.5~2mm, and they are arranged linearly or staggered; the punching speed is 50~200m / min; When using a CO2 laser, the wavelength is set to 10.6 μm, the rated power is 30 W, and the TEM... 00 The beam quality M² is less than 1.2; a ZnSe lens with a focal length of 63mm is used, and the theoretical spot diameter after focusing is approximately 80μm; the coaxial red indicator light is less than 1mW for easy adjustment; the drilling process is performed by scanning line by line in a staggered hexagonal array with a line spacing of 0.87mm and a phase offset of 0.5mm between adjacent lines to ensure uniform tearing stress; the drilling process uses a coaxial CCD to acquire the hole shape, and the image algorithm extracts the hole area A; when |A−A0| / A0>5% (A0 is the calibration value), the laser power is automatically adjusted by ±2% to ensure that the hole diameter CV value is less than 3%.

[0047] Furthermore, in the above technical solution, in the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, a mechanical micro needle roller is used for punching. The outer diameter of the needle roller is set to 120mm, the needle length is set to 250μm, the tip angle is 30°, the material is tungsten carbide, and the hardness is >1800HV. The pressing depth is adjusted to match the thickness of the substrate. The surface of the needle roller is coated with 0.5μm DLC to reduce adhesion. The speed of the needle roller and the film line speed are kept at a tangential speed of 1:1 to reduce tailing deformation. The needle roller is equipped with an anti-static copper wire brush on the side, with a bristle diameter of 0.1mm and a speed of 1500rpm, to guide PET debris into the dust collection box.

[0048] Example 1 (laser punching + laser marking, 120mm wide stand-up pouch, production capacity 10,000 bags / h⁻¹) Step 1, Raw Materials and Pretreatment: The upper substrate is 30µm LDPE with 500ppm erucamide added to reduce the coefficient of friction to 0.18, ensuring a smooth tear. The lower substrate has the same formulation, with an outer surface corona discharge of 42dyncm⁻¹, which meets the requirements for subsequent printing.

[0049] The 12µm PET induction layer was pre-baked at 85℃ and a vacuum of -0.09MPa for 2 hours to reduce the moisture content to 0.2%, preventing the water film from absorbing energy and causing blind holes during laser drilling.

[0050] Step 2: Real-time closed-loop online drilling: The 30W CO2 laser is equipped with a 2bar positive pressure air seal, and the lens contamination alarm threshold is set to power drop >3%, achieving 24-hour maintenance-free operation; after drilling, the weight of the molten bead in a single hole is <0.1µg, which is removed by electrostatic neutralization and negative pressure, leaving no visible dust on the film surface.

[0051] The third step is the integration of point-compounding and cooling: Immediately after hot pressing, the film enters an 18°C ​​cooling roller with an internal flow rate of 1.5 ms⁻¹, ensuring the film exits the roller at 22°C. Simultaneously, a micro-pressure of 0.05 MPa is applied to bond the film to the cooling roller, eliminating heat shrinkage ripples (longitudinal unevenness <10µm).

[0052] The online peel strength tester samples every 50m. If the peel strength is less than 0.5N / 15mm, an alarm is immediately triggered and an additional 2N / mm⁻¹ is applied to ensure stable interlayer bonding.

[0053] Step 4: Laser scribing depth closed loop: The coaxial CCD measures the groove depth every 20mm and the data is transmitted back to the PLC. If the residual thickness is >22µm (tear force is too high), the system automatically increases the power by 1W. If it is <14µm (easily melted), the power is reduced by 1W and the speed is increased by 100mms⁻¹ to maintain a depth of 18±2µm.

[0054] Immediately after marking, air cool (20℃, 0.3MPa) is applied to ensure the groove surface temperature is <35℃, preventing the adhesive layer from sticking back.

[0055] Step 5, Bag Making - Tear Verification: Before inserting the accordion at the bottom of the stand-up pouch, fold it in half at a 30° angle, with the guide line in the center of the crease, to ensure that the bottom remains parallel to the seal after it is formed.

[0056] Online sampling is conducted on every 500 bags for a manual tear test: tearing speed 200mms⁻¹, tear offset <0.5mm, no interlayer separation; seal strength 28N / 15mm, no seal breakage after a 1.2m drop.

[0057] The machine has a speed of 120 mm / min⁻¹, a bag length of 250 mm, a theoretical capacity of 10,000 bags / h⁻¹, an actual operating efficiency of 97%, and a scrap rate of <0.8%.

[0058] Example 2 (micro-needle punching + UV marking, 90mm wide three-side seal bag, production capacity 8500 bags·h⁻¹) Step 1: Precision machining of the micro needle roller: After grinding, the outer cylindrical surface of the needle roller is coated with 0.5µm DLC, reducing the coefficient of friction to 0.1 and increasing the service life from 500h to 2000h; the needle tip radius is ≤2µm, reducing fiber pull-out and preventing fuzzing at the PA membrane pore edges.

[0059] The needle pressure depth is servo-adjusted with a resolution of 1µm and is closed-loop with the thickness gauge. When the thickness of the induced layer fluctuates by ±1µm, the pressure depth is compensated in real time to ensure the pore diameter is 80±5µm.

[0060] The second step, low-temperature point composite process: The steel roller temperature is 105℃, which is 10℃ lower than the conventional temperature to prevent PA from softening and clogging the holes; the rubber roller is circulated with 12℃ cold water, and the surface temperature difference is less than 2℃ to avoid uneven pressure caused by local expansion of the roller surface.

[0061] After lamination, online infrared temperature measurement is performed. Once the film surface temperature is ≤45℃, the film enters the cooling section to reduce lateral relaxation caused by thermal shrinkage (width shrinkage <1mm).

[0062] Step 3, UV laser cold scribing: With high energy of 355nm ultraviolet photons, the absorption coefficient of PET / PA is 8 times higher than that of 10.6µm CO2, and the same depth of processing can be achieved with 15W. The heat-affected zone is only 65µm, resulting in fewer and more brittle molten beads and straighter tearing.

[0063] The scanning head is equipped with a 40kHz ultrapulse with a single-point energy of 0.2mJ, and the groove bottom roughness Ra≤2µm, reducing tear resistance by 15%.

[0064] Step 4: Align the three-side sealed bag: A 0.1mm thick "positioning lip" is added to the outside of the horizontal sealing knife and embedded in the guide line groove. The line position is mechanically fixed during sealing, with a parallelism error of 0.15mm. The lip plate pops up 0.2s after the sealing knife leaves, without sticking.

[0065] The sealing temperature is 132℃, which is 7℃ higher than that of PE bags, but the residence time is shortened to 0.22s, the total heat is reduced, the residual thickness near the guide line is maintained at 15µm, and the tear force is 0.6Nmm⁻¹.

[0066] Application testing The bag is filled with 200mL of water and vacuumed at -0.08MPa for 10s without leakage; the manual tearing speed is 300mms⁻¹, and the tear reaches the bottom in a straight line without deviation; it is dropped 1.5m × 3 times and the seal remains intact.

[0067] With a line speed of 90 mm / min⁻¹, a bag length of 200 mm, a production capacity of 8500 bags / h⁻¹, and power consumption reduced by 12% compared to laser punching solutions, it is suitable for heat-sensitive contents.

[0068] Example 3 (High-speed laser punching + low-power scribing, 160mm wide back seal bag, production capacity 12,000 bags / h⁻¹) Step 1, high-speed laser drilling: A 40W CO2 laser with a 4000mms⁻¹ Galvo was used, with a single-hole time of 40µs and a maximum film speed of 200mmin⁻¹ when the hole spacing was 1.2mm. Nitrogen side blowing (0.4MPa) was used to suppress PET oxidation, and the yellowing index ΔYI at the hole edge was <1.

[0069] Flying Drilling Algorithm: Galvo superimposes the offset in the same direction as the membrane velocity in the MD direction to achieve "stationary-drilling", ensuring roundness >90% without the need to reduce speed.

[0070] The second step is the high thermal conductivity cooling roller: The inner wall of the φ300mm steel roller is plated with copper, which increases the thermal conductivity by 3 times. The flow rate of ethylene glycol water at 5℃ is adjusted to 100Lmin⁻¹, and the film surface temperature is 21℃, leaving sufficient thermal budget for subsequent low-power scribing.

[0071] The cooling section is equipped with an ion air knife with ±8kV and surface static electricity <100V to prevent dust adsorption and laser scattering during high-speed operation.

[0072] Step 3, low-power high-speed line drawing: The 20W CO2 laser was scanned at 1800mms⁻¹, with a residual thickness of 20µm and a linear energy density of only 11Jm⁻¹, which is 40% lower than that of Example 1, and the HAZ was reduced to 98µm; the coaxial vision closed-loop period was 10ms, and the depth fluctuation was ±2µm.

[0073] Immediately after marking, apply 0.35MPa of cold air to keep the groove surface temperature below 30℃ to prevent the low-melting-point modified PE from becoming sticky again.

[0074] Step 4: Forming the back-sealed bag: The back seal width is 10mm, the distance between the center of the longitudinal sealing knife and the guide line is fixed at 8mm, the servo phase adjustment step is 0.05°, ensuring a parallelism of 0.25mm under a width of 160mm; the sealing temperature is 131℃ for 0.25s, the cooling knife is 28℃, and the seal is smooth and wrinkle-free.

[0075] Before sealing, a "micro-vacuum suction hole" is added to remove air from the bag, reducing the impact of a drop on the seal. The back seal strength is 30N / 15mm.

[0076] Production capacity and quality Linear speed 160 mmin⁻¹, bag length 400 mm, theoretical peak 12000 bags·h⁻¹, actual operating 11700 bags·h⁻¹ (efficiency 97.5%); laser head runs continuously for 8 hours without cleaning, power attenuation <2%.

[0077] Tear test: 200mms⁻¹ Manually torn, the tear extends straight to the bottom along the guide line with an offset of <0.3mm; Fully loaded with 2kg of granules, dropped 1.8m × 5 times without breaking the bag, meeting logistics and transportation requirements.

[0078] Specifically, the principle of this invention is as follows: In use, three layers of material are prepared, namely an upper substrate, a lower substrate, and a tearable induction layer; the tearable induction layer is unwound and, after tension control, enters the online punching station for punching; the upper substrate, induction layer, and lower substrate are stacked in sequence and then enter the hot-pressing composite unit for hot-pressing composite; the composite three-layer film is cooled and shaped and then enters the laser marking station for laser marking; the punched and marked composite film is sent to the bag making unit, and after heat sealing and cutting, it forms a single packaging bag, with the guide lines on both sides of the bag body parallel to the seal.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A manufacturing process for easy-tear plastic packaging bags, characterized in that, The specific steps include: S10: Prepare three layers of material, namely the upper substrate, the lower substrate, and the tear-inducing layer; S20: The tearable induction layer is unwound and, after tension control, enters the online punching station for punching; S30: The upper substrate, the inducing layer and the lower substrate are stacked in sequence and then put into the hot pressing composite unit for hot pressing composite; S40: After the composite three-layer film material is cooled and shaped, it enters the laser scribing station for laser scribing. S50: The perforated and marked composite film material is fed into the bag making unit, and after heat sealing and cutting, it forms a single packaging bag. The guide lines on both sides of the bag are parallel to the seal.

2. The manufacturing process for an easy-tear plastic packaging bag according to claim 1, characterized in that, Both the upper substrate and the lower substrate are made of PE or PP film with a thickness of 20~80μm; the tear-inducing layer is made of PET, PA or modified PE film with a thickness of 5~25μm; the thickness of the tear-inducing layer is less than 1 / 2 of the thickness of the upper substrate or the lower substrate, and the total thickness of the upper substrate, the lower substrate and the tear-inducing layer after lamination is 60~90μm; the upper substrate and the lower substrate are corona treated on the side closest to the tear-inducing layer.

3. The manufacturing process for an easy-tear plastic packaging bag according to claim 2, characterized in that, During the hot-pressing process of stacking the upper substrate, the inducing layer, and the lower substrate in sequence and then entering the hot-pressing composite unit, a convex array is set on the surface of the hot-pressing roller. The diameter of the convex dots is set to 0.3~1mm, and the distribution density is set to 5~20 dots / cm². The hot-pressing temperature is set to 90~130℃. Only the area corresponding to the convex dots forms a weak point bond, while the other areas remain loosely bonded. The upper roller of the hot press roller is made of steel with hard chrome plating on the surface and is equipped with a 6-head spiral heat-conducting oil circulation in the inner cavity; the lower roller is made of silicone rubber with a silicone thickness of 20mm; the roller surface width is 650mm; and hydraulic cylinders are configured at both ends.

4. The manufacturing process for an easy-tear plastic packaging bag according to claim 3, characterized in that, The specific steps for hot-pressing the upper substrate, the inducing layer, and the lower substrate in sequence into the hot-pressing composite unit include: The first step is to stack the upper substrate, the induction layer, and the lower substrate in sequence to form a three-layer composite blank. The second step is to set the temperature of the steel roller to 90-130℃ and the temperature of the rubber roller to ≤45℃. The third step is to adjust the linear pressure so that the local pressure at the protrusion is 3~5MPa. In the fourth step, the PE surface layer of the upper and lower substrates is melted in the bumped area, with a melt depth of 5~8µm, and a dotted heat seal is formed with the TI surface; the non-bumped area remains unbonded or peelable. The fifth step is to immediately pass the film through a 25°C cooling roller after it exits the pressure zone to reduce the surface temperature of the composite film to ≤45°C, thus completing the shaping process.

5. The manufacturing process for an easy-tear plastic packaging bag according to claim 4, characterized in that, After the composite three-layer membrane material is cooled and shaped, it enters the laser scribing station for laser scribing. In this process, a CO2 or UV laser is used to scribing straight guide lines on both sides of the membrane material at a distance of 5-15 mm from the bag seal. The scribing depth is 10-30% of the total thickness of the membrane material. The cooling and shaping process is carried out using a main cooling roller and an auxiliary cooling roller. The main cooling roller is a double-layer spiral flow channel steel roller, and the auxiliary cooling roller is a silicone rubber roller. It is cooled by circulating ethylene glycol-water at 5°C, with a volume ratio of ethylene glycol to water of 3:

7. The specific steps for cooling and shaping the composite three-layer membrane are as follows: The first step is to immediately introduce the hot-pressed composite three-layer film into the cooling zone, where it will remain for 0.4 to 0.6 seconds. The second step is to use a vortex fan to assist in heat dissipation on the non-contact surface, ensuring that the film surface temperature is ≤25℃ before leaving the cooling zone; The third step involves using an infrared thermometer to provide closed-loop feedback to the frequency converter pump, enabling real-time adjustment of the roller temperature. The fourth step is to install an electrostatic eliminator at the outlet of the cooling section to prevent dust from adhering and causing laser energy scattering.

6. The manufacturing process for an easy-tear plastic packaging bag according to claim 5, characterized in that, The specific steps for laser scribing of the composite three-layer film material after cooling and shaping include: The first step is to introduce the cooled three-layer composite film into the laser scribing station while maintaining the tension on the surface. The second step is to set the laser power and scanning speed; The third step involves continuously drawing two straight guide lines along the scanning head; The fourth step is to use a coaxial vision system to collect the depth of the scribing groove in real time; The fifth step is to immediately blow and cool the groove after marking it, so that the surface temperature of the groove is ≤40℃, and then put it into the storage rack.

7. The manufacturing process for an easy-tear plastic packaging bag according to claim 6, characterized in that, The specific steps of feeding the perforated and marked composite film into the bag-making unit, and forming individual packaging bags after heat sealing and cutting, with the guide lines on both sides of the bag body parallel to the seal, include: Step 1, Material Storage and Transition: The swing roller type material storage rack supplies film to the bag making machine, ensuring 15 seconds of continuous material supply during zero-speed roll change; The second step is correction and positioning: the accuracy is controlled by the edge of the EPC, and the bag is centered in the width direction; The third step is longitudinal sealing: the servo traction speed is equal to the film linear speed, the heat sealing knife temperature is set to 125±3℃, the sealing width is set to 10mm, and the cooling pressure roller is set to ≤30℃. Step 4, horizontal sealing of top and bottom: adopt double-set rotating horizontal sealing blades, with temperature set at 130±2℃, pressure set at 0.35MPa, and cooling blade temperature ≤35℃; Step 5, guide line alignment: ensure that the parallelism between the center line of the horizontal sealing knife and the laser guide line is ≤0.2mm; Step 6, online cutting: The servo flying shear is synchronized with the film speed, and the cutting speed ratio is 1:1; Step 7, Finished Product Output: The vacuum conveyor belt delivers the single bags, which are counted and stacked. The parallelism deviation between the guide lines on both sides of the bag and the seal is ≤0.3mm.

8. The manufacturing process for an easy-tear plastic packaging bag according to claim 7, characterized in that, In the specific steps of unwinding the tearable induction layer, an ultrasonic sensor is used to monitor the roll diameter in real time, and the target tension range is set to 20±2N. During the online drilling process after tension control, an exhaust vent is installed at the bottom of the equipment, which is equipped with a 3-stage filter. When the differential pressure sensor reaches >300Pa, an alarm is triggered and the filter element needs to be replaced.

9. The manufacturing process for an easy-tear plastic packaging bag according to claim 8, characterized in that, In the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, CO2 or UV is used for punching to form an intermittent micropore array on the surface of the inducing layer; the micropore diameter is 50~300μm, the spacing between the pores is 0.5~2mm, and they are arranged linearly or staggered. When using a CO2 laser, the wavelength is set to 10.6 μm; a ZnSe lens with a focal length of 63 mm is used; the drilling process is performed by scanning line by line in a staggered hexagonal array with a line spacing of 0.87 mm to ensure uniform tearing stress; the hole shape is acquired by a coaxial CCD during the drilling process, and the hole area A is extracted by an image algorithm; when |A−A0| / A0>5%, the laser power is automatically adjusted to ensure that the hole diameter CV value is <3%.

10. The manufacturing process for an easy-tear plastic packaging bag according to claim 9, characterized in that, In the step of unwinding the tearable inducing layer and, after tension control, entering the online punching station for punching, a mechanical micro needle roller is used for punching. The outer diameter of the needle roller is set to 120mm, the needle length to 250μm, the tip angle to 30°, and the material to be tungsten carbide. The pressing depth is adjusted to match the thickness of the substrate. The surface of the needle roller is coated with 0.5μm DLC to reduce adhesion. The rotation speed of the needle roller is kept at a tangential speed of 1:1 with the film linear speed to reduce tailing deformation. The needle roller is equipped with an anti-static copper wire brush on the side, with a bristle diameter of 0.1mm and a rotation speed of 1500rpm, to guide PET debris into the dust collection box.

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