A flexible high-temperature-resistant retort-easy-to-tear cover sealing composite material and a preparation method thereof

Abstract

The present application relates to the technical field of easy-to-tear cover, and in particular to a flexible high-temperature-resistant cooking easy-to-tear cover sealing composite material and a preparation method, the preparation method comprising: performing pattern printing on a PET film to output a PET inner printing film; adjusting the glue application speed of the PET inner printing film and the immersion depth of a glue application roller in a glue tank based on the glue bubble density of the PET inner printing film; determining the drying machine temperature according to the bubble distribution length of the PET inner printing film and the distance between drying rollers; determining the compression temperature of a composite roller and the tension of a winding shaft according to the tension difference; performing actual dry compounding on the PET inner printing film and an aluminum foil according to the above adjustment parameters to output a PET inner printing-aluminum foil film; sequentially performing peel strength testing and PE heat sealing layer film compounding on the PET inner printing-aluminum foil film to output a target easy-to-tear cover film, and sequentially performing curing and slitting on the target easy-to-tear cover film to output a flexible high-temperature-resistant cooking easy-to-tear cover film. The present application improves the flatness and interlayer bonding strength of each layer of the flexible high-temperature-resistant cooking easy-to-tear cover film.

Description

Technical Field

[0001] This invention relates to the field of easy-tear cap sealing composite materials, and in particular to a flexible, high-temperature resistant, easy-tear cap sealing composite material and its preparation method. Background Technology

[0002] In the existing technology, aluminum foil easy-tear caps, as a packaging material, are widely used in the food, beverage, pharmaceutical, and cosmetic fields due to their advantages such as being non-toxic, odorless, aesthetically pleasing, easy to open, and recyclable. In the packaging industry, PET material, due to its printability, toughness, and puncture resistance, improves the wear resistance, appearance, and surface gloss of packaging. PE has excellent tearability, flatness, and heat-sealing properties, providing a guarantee for independent packaging of food and pharmaceutical products.

[0003] Chinese Patent Publication No. CN119820938A discloses a high-temperature retortable aluminum foil easy-tear lid and its preparation process. It includes a protective layer, a first reinforcing layer, an aluminum foil layer, a second reinforcing layer, and a heat-sealing layer. The protective layer is adhesively bonded to the first reinforcing layer, the first reinforcing layer is adhesively bonded to the aluminum foil layer, the aluminum foil layer is adhesively bonded to the second reinforcing layer, and the second reinforcing layer is adhesively bonded to the heat-sealing layer. The protective layer is made of modified polyvinyl alcohol, and both the first and second reinforcing layers are made of composite reinforcing materials. This invention uses gentian acid with antibacterial properties and inorganic nanoparticles cross-linked modified polyvinyl alcohol as the protective layer. Gentian acid contains phenolic hydroxyl groups, which extends its service life.

[0004] Therefore, the high-temperature cooking process for easy-tear aluminum foil caps has several drawbacks. Firstly, the process lacks a mechanism for detecting and adjusting adhesive bubbles. Secondly, the dry lamination process easily generates numerous bubbles in the adhesive layer, leading to cap film delamination and leaks at the sealing point. Furthermore, the process suffers from insufficient adhesive drying in wrinkled areas and excessive residual adhesive solvent. Summary of the Invention

[0005] Therefore, the present invention provides a flexible, high-temperature resistant, easy-tear cap sealing composite material and its preparation method, in order to overcome the problems in the prior art where the layers of the cap film separate after high-temperature sterilization, the ink is easy to fall off during the sterilization process, and the glue bubbles on the film after coating interfere with the composite effect of the film.

[0006] To achieve the above objectives, on the one hand, the present invention provides a method for preparing a flexible, high-temperature resistant, easy-tear cap sealing composite material, comprising: A gravure printing machine is used to print patterns on PET film to output PET back-printed film; The aluminum foil roll and the PET reverse-printed film were dry-laminated using a dry laminating machine. Obtain the bubble distribution area on the surface of the PET reverse-printed film; The density of adhesive bubbles in the bubble distribution area on the surface of the dried PET back-printed film was measured. The gluing speed of the PET back-printed film and the depth of the gluing screen roller immersed in the glue bath are adjusted based on the glue bubble density. The bubble distribution length is determined based on the bubble distribution region; The drying temperature for PET reverse-printed film is determined based on the bubble distribution length and the roller spacing of the drying rollers in the dry laminating machine. The first tension of the film before it enters the dryer in the bubble distribution area and the second tension of the film when the bubble distribution area is inside the dryer are obtained. The pressing temperature of the composite roller and the actual tension of the take-up shaft are determined based on the difference between the second tension and the first tension. The PET back-printed film and aluminum foil roll are actually dry-laminated according to the glue application speed of the PET back-printed film, the immersion depth in the glue bath, the drying temperature of the PET back-printed film, the pressing temperature of the composite roller, and the actual tension of the winding shaft, so as to output PET back-printed aluminum foil film. The PET-printed aluminum foil film is subjected to peel strength test and PE heat-sealing film composite to output the target easy-tear cap film. The target easy-tear cap film is then cured and cut to output a flexible, high-temperature resistant, easy-tear cap sealing composite material.

[0007] Furthermore, adjusting the adhesive application speed and immersion depth of the PET underprinted film based on the adhesive bubble density includes: The density of the glue bubbles is compared with the bubble density threshold. If the density of the glue bubbles is greater than or equal to the bubble density threshold, it is determined that the glue application speed and immersion depth of the PET back-printed film are abnormal. In this case, the glue application speed of the PET back-printed film is reduced and the immersion depth in the glue tank is increased.

[0008] Further, determining the drying temperature of the PET reverse-printed film based on the bubble distribution length and the roller spacing of the drying rollers in the dry laminating machine includes: The length of the bubble distribution is compared with the gap between the drying rollers; If the length of the bubble distribution is greater than the gap between the drying rollers, it is determined that the risk of wrinkling of the PET back-printed film in the dryer does not meet the requirements, and the drying temperature of the PET back-printed film is increased.

[0009] Further, determining the pressing temperature of the composite roller and the actual tension of the take-up shaft based on the actual tension difference between the second tension and the first tension includes: The actual tension difference is compared with the tension difference threshold. If the actual tension difference is greater than or equal to the tension difference threshold, it is determined that the risk of wrinkling of the PET back-printed film in the dryer and the degree of glue drying do not meet the requirements. Therefore, the pressing temperature of the composite roller is increased and the tension of the take-up shaft is increased. Wherein, the first tension is the tension of the bubble distribution area of ​​the film before entering the dryer; the second tension is the tension of the film between the dryer and the conveyor roller after the bubble distribution area of ​​the film enters the dryer.

[0010] Furthermore, the bubble distribution area is the largest planar area enclosed by the straight lines connecting the center point of each bubble on the film to the center point of the adjacent bubble.

[0011] Furthermore, the timing for adjusting the pressing temperature of the composite roller and the tension of the winding shaft is determined based on the position of the film in the pleated state in the dryer and the film conveying speed. The moment when the film is in a wrinkled state after a specific time is determined as the moment when the pressing temperature of the composite roller is adjusted. The specific duration is the ratio of the length of the film from the position where the film is in a wrinkled state to the pressing position to the film's conveying speed.

[0012] Furthermore, the moment when the film is in a wrinkled state is determined based on the first tension and the second tension.

[0013] Furthermore, the moment when the actual tension difference between the first tension and the second tension satisfies the tension condition is determined as the moment when the film is in a wrinkled state; The tension condition is that the difference between the first tension and the second tension is greater than a tension difference threshold.

[0014] Furthermore, the position of the folded state is determined based on the difference between the moving length of the bubble distribution area and the length of the inclined conveying section; The moving length of the bubble distribution area is the product of the interval between the moment when the film is in a wrinkled state and the moment when the bubble distribution area is monitored, and the film's conveying speed.

[0015] On the other hand, the present invention provides a flexible, high-temperature resistant, easy-tear cap sealing composite material prepared using a method for preparing a flexible, high-temperature resistant, easy-tear cap sealing composite material, comprising PET, ink, adhesive, aluminum foil, adhesive and PE arranged in the order from the outside to the inside.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: the preparation method of the present invention replaces the method of printing the pattern on the surface of aluminum foil with printing the pattern on PET film, and the side of the PET film with the pattern is laminated with the aluminum foil to ensure the integrity of the ink during high-temperature cooking and transportation; in the process of preparing the easy-tear cap, when the degree to which the gluing roller is immersed in the glue tank is not in accordance with the film gluing speed on the gluing unit, more air bubbles will be generated on the film surface. When pressed with the film on the other side, the quality of the output composite film is reduced. Adjusting the depth of the gluing roller immersed in the glue tank and the film gluing speed reduces the density of glue bubbles on the film, so as to output a composite film with tightness and strong adhesion; when When air bubbles appear on the film in the gluing unit, these bubbles reduce the film tension and cause wrinkles. When the film enters the dryer, the glue accumulates in the wrinkled areas, preventing it from drying properly and resulting in insufficient glue solvent residue. By adjusting the temperature inside the dryer, the glue solvent residue in the wrinkled areas is brought up to the standard. As the glue in the wrinkled areas dries and solidifies, when it passes through the composite roller and is laminated with the unwinding unit on the other side, wrinkles, gaps, and even glue overflow occur between the two layers of film. By adjusting the temperature of the composite roller, the glue in the wrinkled areas becomes more fluid as it passes through the composite roller, eliminating residual glue bubbles. At the same time, the winding speed of the take-up shaft is increased to restore the glued film to the preset tension.

[0017] Furthermore, during the film coating process, if the coating roller is immersed too shallowly in the glue tank, turbulence and splashing will occur in the glue tank when the coating roller rotates. Due to the low liquid level, the generated air bubbles are difficult to eliminate in a short time and are continuously carried up by the coating roller. Consequently, foamy glue containing air bubbles adheres to the film. When the film coating speed is high, the squeegee needs to increase its speed to scrape off the excess glue, resulting in more air being mixed into the glue tank and creating glue bubbles. By adjusting the depth of the coating roller immersed in the glue tank, the surface of the glue tank is kept calm, reducing violent turbulence and splashing. By adjusting the film coating speed and reducing the squeegee speed, the probability of air being mixed into the glue tank is reduced, ultimately ensuring that the density of glue bubbles on the film reaches the allowable range.

[0018] Furthermore, after the film is coated with adhesive, air bubbles are generated. Because the liquid adhesive has surface tension on the film surface, and there is less adhesive at the location of the air bubbles, a tensile force is generated due to the difference in surface tension, causing the film itself to wrinkle. Adhesive on both sides will accumulate at the wrinkles. After entering the dryer, the adhesive at the wrinkles cannot meet the drying requirements and there is a lot of adhesive solvent residue. By adjusting the temperature of the dryer, the adhesive at the wrinkles is finally dried and the adhesive solvent is fully evaporated.

[0019] Furthermore, due to the wrinkling in the bubble distribution area, the tension of the film decreases before entering the dryer. After the wrinkled part enters the dryer and dries the adhesive, a second tension change occurs. By calculating the tension difference between the two times and the wrinkle position, the timing for adjusting the temperature of the composite roller, the temperature of the composite roller, and the tension of the winding shaft are obtained, ultimately resulting in a tightly packed composite film. Attached Figure Description

[0020] Figure 1 This is an overall flowchart of the preparation method of the flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating step S1 of the method for preparing a flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating step S11 of the method for preparing a flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the microstructure of the flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the dry laminating machine working process in the preparation of the flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached drawings: 1-Glue tank, 2-Gluing screen roller, 3-Left unwinding unit, 4-Drying screen roller, 5-Dryer, 6-Right unwinding unit, 7-Pressing unit, 8-Rewinding unit. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0025] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Please see Figure 1 The diagram shown is an overall flowchart of the preparation method of the flexible, high-temperature resistant, easy-tear cap sealing composite material according to an embodiment of the present invention. The preparation method of this embodiment includes: Step S1: Use a gravure printing machine to print patterns on the PET film to output PET back-printed film; Step S2: Perform a dry lamination test on the aluminum foil roll and the PET back-printed film using a dry laminator; Step S3: Obtain the bubble distribution area on the surface of the PET printed film; Step S4: Detect the density of adhesive bubbles in the bubble distribution area on the surface of the dried PET back-printed film. Step S5: Adjust the gluing speed of the PET back-printed film and the depth of the gluing screen roller immersed in the glue tank based on the glue bubble density. Step S6: Determine the bubble distribution length based on the bubble distribution area; Step S7: Determine the drying temperature for the PET reverse printing film based on the bubble distribution length and the roller spacing of the drying rollers in the dry laminating machine. Step S8: Obtain the first tension of the film before it enters the dryer in the bubble distribution area and the second tension of the film when the bubble distribution area is inside the dryer; Step S9: Determine the pressing temperature of the composite roller and the actual tension of the take-up shaft based on the difference between the second tension and the first tension; Step S10: Perform actual dry lamination of the PET back-printed film and aluminum foil roll according to the glue application speed of the PET back-printed film, the immersion depth in the glue bath, the drying temperature of the PET back-printed film, the pressing temperature of the composite roller, and the actual tension of the winding shaft to output PET back-printed aluminum foil film. Step S11: The PET back-printed aluminum foil film is subjected to peel strength test and PE heat-sealing layer film composite to output target easy-tear cap film. The target easy-tear cap film is then cured and cut to output flexible, high-temperature resistant, easy-tear cap sealing composite material.

[0027] In this embodiment, step S1 includes: Step S11: Select ink and adjust the ink viscosity to within 30 mPa·s-80 mPa·s; Step S12: Set the PET film tension and control the PET film tension within the range of 98N-117N; Step S13: Start the main motor of the gravure printing machine, turn on the drying equipment and blower, and at the same time ensure that the hot air circulation system in the oven is working properly in preparation for the formal printing. Step S14: Perform longitudinal and transverse registration calibration between each printing color group; In step S15, the PET film is preheated to about 50°C by a heating roller before printing begins to improve the adhesion of the ink; after the pattern printing is completed, the PET film is put into an oven for drying to output the PET reverse-printed film.

[0028] In this embodiment, step S4 includes: Step S41: Compare the glue bubble density with the bubble density threshold. Step S42: If the density of the glue bubbles is greater than or equal to the bubble density threshold, it is determined that the glue application speed and the immersion depth of the PET back-printed film are abnormal. Then, the glue application speed of the PET back-printed film is reduced and the immersion depth in the glue tank is increased. Among them, the density of glue bubbles is obtained by monitoring the bubble distribution area using a high-speed vision sensor; In this embodiment, by increasing the immersion depth in the glue tank, the degree of tumbling and splashing of glue in the glue tank caused by the rotation of the glue application screen roller is reduced, thereby reducing the density of air bubbles in the glue tank and reducing the probability of glue bubbles adhering to the PET back-printed film. It is understandable that when adhesive-coated PET film is laminated with aluminum foil, the lower the interlayer peel strength, the higher the density of adhesive bubbles in the PET film; and the higher the interlayer peel strength, the lower the density of adhesive bubbles in the PET film. In this embodiment, the bubble distribution area is the largest planar area enclosed by the straight lines connecting the center point of each bubble on the film to the center point of the adjacent bubble; The bubble density threshold is determined based on the peel strength test results of the PET-aluminum foil film after lamination of the two films, to ensure that the peel strength test results of the PET-aluminum foil film meet the requirements. When the bubble density threshold is too small, although the peel strength can be guaranteed to meet the standard, it will increase the difficulty of controlling the adhesive application process, resulting in a decrease in production efficiency. When the bubble density threshold is too large, too many bubbles in the adhesive will damage the tightness of the composite layer, resulting in the PET-aluminum foil film peel strength not meeting the standard. After high-temperature cooking, problems such as delamination and leakage are likely to occur, failing to meet product quality requirements. Therefore, this embodiment sets the bubble density threshold within a range that can ensure both production efficiency and cost control, while ensuring that the peel strength of the laminated film meets the standard, in order to achieve a balance between process efficiency and product quality. The reduced adhesive application speed of the PET reverse printing film is determined based on the difference between the adhesive bubble density and the bubble density threshold. The adhesive application speed of the PET reverse printing film is positively correlated with the adhesive bubble density; for every 10 bubbles / m increase in the adhesive bubble density difference... 2 The gluing speed of the PET film is reduced to 1% of the original gluing speed.

[0029] In this embodiment, step S6 includes: Step S61: Compare the bubble distribution length with the roller spacing of the drying roller; In step S62, if the length of the bubble distribution is greater than the gap between the drying rollers, it is determined that the risk of wrinkling of the PET back-printed film in the dryer does not meet the requirements, and the drying temperature of the PET back-printed film is increased.

[0030] In this embodiment, by increasing the drying temperature of the dryer, the glue accumulated in the wrinkled areas of the PET back-printed film is fully dried, and the glue solvent is fully evaporated to ensure that the residual amount of glue solvent meets the requirements. Understandably, the greater the bubble distribution length compared to the drying roller spacing, the greater the wrinkles on the PET inner printing film surface and the more adhesive solvent residue; conversely, the smaller the bubble distribution length compared to the drying roller spacing, the less wrinkled the PET inner printing film surface and the less adhesive solvent residue. The method for determining the residual amount of adhesive solvent refers to GB 38508-2020 "Determination of Residual Solvents in Composite Packaging Materials and Products for Food Contact". Gas chromatography is used for detection. The operation procedure is as follows: Select the dried PET back-printed film as the sample, cut it into 10cm×10cm samples, put it into a headspace vial and seal it. Heat it at 80℃ for 30min to allow the adhesive solvent to fully evaporate. Then, use a gas chromatograph to determine the peak area of ​​the adhesive solvent in the headspace vial and calculate the residual amount of adhesive solvent. In this embodiment, the standard adhesive solvent residue threshold is set at 5 mg / m², which is determined based on the national standard for composite packaging materials for food contact. If the solvent residue is greater than 5 mg / m², the adhesive in the wrinkled area will not dry sufficiently, the adhesive will not cure completely, the peel strength between the PET printed film and the aluminum foil will decrease, and the risk of delamination during retort testing will increase. If the solvent residue is less than or equal to 5 mg / m², the adhesive will be fully cross-linked and cured, and there will be no unvolatile solvent isolation layer between the film layers to ensure that no secondary bubbles are generated during the high-temperature retort test. The residual amount of adhesive solvent in PET back-printed films is negatively correlated with the temperature of the dryer. That is, the higher the temperature of the dryer, the more fully the adhesive solvent evaporates and the lower the residual amount; conversely, the lower the temperature, the higher the residual amount of solvent. If the detected residual amount of adhesive solvent is higher than the standard adhesive solvent residual amount threshold, the temperature of the dryer needs to be further increased. For every 1 mg / m² of residual adhesive solvent exceeding the standard adhesive solvent residual amount threshold, the drying temperature should be increased by 3℃-5℃. In this embodiment, step S9 includes: Step S91: Obtain the first tension of the PET reverse printing film before entering the dryer in the bubble distribution area and the second tension of the PET reverse printing film between the dryer and the conveyor roller in the bubble distribution area of ​​the PET reverse printing film after entering the dryer. Step S92: Subtract the first tension from the second tension to obtain the actual tension difference value; Step S93: Compare the actual tension difference with the tension difference threshold; Step S94: If the actual tension difference is greater than the tension difference threshold, increase the pressing temperature of the composite roller and increase the tension of the take-up shaft. The tension difference threshold is determined by referring to the conventional parameter range of the dry lamination process and considering the compatibility of PET reverse-printed film with aluminum foil lamination. If the tension difference threshold is too small, the adjustment of the lamination roller's pressing temperature and the actual tension of the winding shaft will be insensitive, and the risk of wrinkles cannot be handled in a timely manner. If the tension difference threshold is too large, the adjustment of the lamination roller's pressing temperature and the actual tension of the winding shaft will be excessive, resulting in problems such as overly tight bonding and film stretching deformation during the film lamination process. Therefore, this embodiment sets the tension difference threshold within the range that distinguishes between normal film tension fluctuations and tension changes caused by abnormal wrinkles, ensuring timely and accurate adjustment of the lamination roller's pressing temperature and the actual tension of the winding shaft. The pressing temperature of the composite roller and the tension of the take-up shaft in the enlarged dry laminating machine are determined based on the actual tension difference. The actual tension difference is positively correlated with the pressing temperature of the composite roller and the tension of the take-up shaft. The higher the actual tension difference is compared to the tension difference threshold, the higher the pressing temperature of the composite roller and the actual tension of the take-up shaft. The composite roll pressing temperature adjustment range is 90℃-110℃, and the take-up shaft tension adjustment range is 60N-80N. For every 0.1N / m that the actual tension difference exceeds the tension difference threshold, the composite roll pressing temperature will increase by 3℃-5℃, and the take-up shaft tension will increase by 5N-8N. The first tension is the tension of the film's bubble distribution area before entering the dryer; the second tension is the tension of the film between the dryer and the conveyor rollers after entering the dryer, where the film's bubble distribution area is located. In this embodiment, by increasing the pressing temperature of the composite roller and the tension of the winding shaft, the adhesive at the wrinkled position of the PET reverse-printed film after passing through the dryer is activated by the composite roller to increase its fluidity. By increasing the tension of the winding shaft, the tension of the film at the wrinkled position is restored to the tension that meets the requirements of conventional dry lamination process and is suitable for the lamination of PET reverse-printed film and aluminum foil, thereby optimizing the peel strength test value after the PET reverse-printed film and aluminum foil are laminated.

[0031] In this embodiment, the timing for adjusting the pressing temperature of the composite roller and the tension of the winding shaft is determined based on the position of the film in the pleated state in the dryer and the film conveying speed. Among them, the moment after a specific time elapses when the PET back-printed film is in a wrinkled state is determined as the moment to adjust the pressing temperature of the composite roller; The specific duration is the ratio of the length of the PET back-printed film that it travels from the position where the PET back-printed film is in a wrinkled state to the position where the composite roller is pressed, to the conveying speed of the film. Specifically, the PET reverse printing film is in a wrinkled state based on the first tension and the second tension; the difference between the moving length of the bubble distribution area and the length of the inclined conveying section determines the position in the wrinkled state; wherein, the moving length of the bubble distribution area is the product of the interval between the moment when the film is in a wrinkled state and the monitoring moment of the bubble distribution area and the conveying speed of the PET reverse printing film. Specifically, the moment when the first tension and the second tension meet the tension condition is determined as the moment when the film is in a wrinkled state; the larger the tension difference is than the tension difference threshold, the more obvious the wrinkled state of the PET back-printed film is. The tension condition is that the actual tension difference is greater than the tension difference threshold.

[0032] In this embodiment, step S11 includes: Step S111: Test the PET back-printed aluminum foil film using a peel strength test; Step S112: The PET-aluminum foil film and PE film are laminated using the process of laminating PET-printed film and aluminum foil to output the target easy-tear cover film. Step S113: Perform a peel strength test on the target easy-tear film; Step S114: The target easy-tear cap film is sequentially cured and cut to output a flexible, high-temperature resistant, easy-tear cap sealing composite material.

[0033] In this embodiment, the test steps for the peel strength of the PET reverse-printed aluminum foil film include: Cut a sample 15mm wide and 200mm long from the PET back-printed aluminum foil film; Pre-peel the PET film and aluminum foil from one end of the sample, with a peeling length of ≥50mm; The sample was placed in an environmental control chamber at a temperature of 24℃ and a relative humidity of 50%±5% for 4 hours. Clamp the pre-peeled PET film end and aluminum foil end into the upper and lower clamps of the tensile testing machine respectively, so that the sample is pulled apart at a constant speed, and the effective peel length should be ≥100mm; The testing machine's sensors automatically record the force-displacement curve during the peeling process, select the section with relatively stable peeling force, remove the initial peak and the tail-end fluctuation, and calculate the average peeling force of the section with relatively stable peeling force.

[0034] This embodiment describes a flexible, high-temperature resistant, easy-tear sealing composite material, which consists of PET, ink, adhesive, aluminum foil, adhesive, and PE arranged in the order from the outside to the inside.

[0035] In this embodiment, the PET film is a polyester film, which serves as the pattern printing layer. It is transparent and has a thickness of 25μm-50μm. The aluminum foil serves as an oxygen and vapor barrier layer with a thickness of 40μm. The PE film is a polyethylene film, which serves as the heat-sealing layer with a thickness of 30μm-50μm.

[0036] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible, high-temperature resistant, easy-tear cap sealing composite material, characterized in that, include: A gravure printing machine is used to print patterns on PET film to output PET back-printed film; The aluminum foil roll and the PET reverse-printed film were dry-laminated using a dry laminating machine. Obtain the bubble distribution area on the surface of the PET reverse-printed film; The density of adhesive bubbles in the bubble distribution area on the surface of the dried PET back-printed film was measured. The gluing speed of the PET back-printed film and the depth of the gluing screen roller immersed in the glue tank are adjusted based on the glue bubble density. The bubble distribution length is determined based on the bubble distribution region; The drying temperature for PET reverse-printed film is determined based on the bubble distribution length and the roller spacing of the drying rollers in the dry laminating machine. The first tension of the film before it enters the dryer in the bubble distribution area and the second tension of the film when the bubble distribution area is inside the dryer are obtained. The pressing temperature of the composite roller and the actual tension of the take-up shaft are determined based on the difference between the second tension and the first tension. The PET back-printed film and aluminum foil roll are actually dry-laminated according to the glue application speed of the PET back-printed film, the immersion depth in the glue bath, the drying temperature of the PET back-printed film, the pressing temperature of the composite roller, and the actual tension of the winding shaft, so as to output PET back-printed aluminum foil film. The PET-printed aluminum foil film is subjected to peel strength test and PE heat-sealing film composite to output the target easy-tear cap film. The target easy-tear cap film is then cured and cut to output a flexible, high-temperature resistant, easy-tear cap sealing composite material.

2. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 1, characterized in that, The method of adjusting the adhesive application speed and immersion depth of the PET back-printed film based on the adhesive bubble density includes: The density of the glue bubbles is compared with the bubble density threshold. If the density of the glue bubbles is greater than or equal to the bubble density threshold, it is determined that the glue application speed and immersion depth of the PET back-printed film are abnormal. In this case, the glue application speed of the PET back-printed film is reduced and the immersion depth in the glue tank is increased.

3. The flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 2 and its preparation method, characterized in that, The step of determining the drying temperature of the PET reverse-printed film based on the bubble distribution length and the roller spacing of the drying rollers in the dry laminating machine includes: The length of the bubble distribution is compared with the gap between the drying rollers; If the length of the bubble distribution is greater than the gap between the drying rollers, it is determined that the risk of wrinkling of the PET back-printed film in the dryer does not meet the requirements, and the drying temperature of the PET back-printed film is increased.

4. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 3, characterized in that, Determining the pressing temperature of the composite roller and the actual tension of the take-up shaft based on the actual tension difference between the second tension and the first tension includes: The actual tension difference is compared with the tension difference threshold. If the actual tension difference is greater than or equal to the tension difference threshold, it is determined that the risk of wrinkling of the PET back-printed film in the dryer and the degree of glue drying do not meet the requirements. Therefore, the pressing temperature of the composite roller is increased and the tension of the take-up shaft is increased. Wherein, the first tension is the tension of the bubble distribution area of ​​the film before entering the dryer; the second tension is the tension of the film between the dryer and the conveyor roller after the bubble distribution area of ​​the film enters the dryer.

5. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 4, characterized in that, The bubble distribution area is the largest planar area enclosed by the straight lines connecting the center point of each bubble on the film to the center point of the adjacent bubble.

6. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 5, characterized in that, The timing for adjusting the pressing temperature of the composite roller and the tension of the winding shaft is determined based on the position of the film in the pleated state in the dryer and the film conveying speed. The moment when the film is in a wrinkled state after a specific time is determined as the moment when the pressing temperature of the composite roller is adjusted. The specific duration is the ratio of the length of the film from the position where the film is in a wrinkled state to the pressing position to the film's conveying speed.

7. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 6, characterized in that, The moment when the film is in a wrinkled state is determined based on the first tension and the second tension.

8. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 7, characterized in that, The moment when the actual tension difference between the first tension and the second tension satisfies the tension condition is defined as the moment when the film is in a wrinkled state. The tension condition is that the difference between the first tension and the second tension is greater than a tension difference threshold.

9. The method for preparing the flexible, high-temperature resistant, easy-tear cap sealing composite material according to claim 8, characterized in that, The position of the bubble in the folded state is determined by the difference between the moving length of the bubble distribution area and the length of the inclined conveying section. The moving length of the bubble distribution area is the product of the interval between the moment when the film is in a wrinkled state and the moment when the bubble distribution area is monitored, and the film's conveying speed.

10. A flexible, high-temperature resistant, easy-tear cap sealing composite material prepared using the method for preparing the flexible, high-temperature resistant, retortable, easy-tear cap sealing composite material according to any one of claims 1-9, characterized in that, This includes PET, ink, adhesive, aluminum foil, and PE arranged in order from the outside in.

Images