Corona differentiated treatment anti-uncovering mark-remaining unsealing stay wire and preparation method thereof

Abstract

The invention belongs to the technical field of packaging anti-counterfeiting materials, and provides a corona differentiated treatment anti-uncovering mark-remaining unsealing pull wire and a preparation method thereof. The unsealing stay wire sequentially comprises a base film layer, a corona shielding layer, a selective corona enhancement layer, an adhesive layer and a printing ink layer from bottom to top. The corona shielding layer is coated in a full-breadth manner and contains organic silicon resin and nano silicon dioxide; and the selective electro-hydraulic reinforcing layer is coated on the anti-counterfeiting pattern area in a patterning manner and contains hydroxyl acrylic resin, maleic anhydride grafted polypropylene and nano aluminum oxide. Through two-stage gradient corona treatment, the corona value of the enhancement layer area reaches 48 dynes to 52 dynes, the corona value of the shielding layer area reaches 25 dynes to 28 dynes, and the difference between the corona values of the enhancement layer area and the shielding layer area is 20 dynes to 27 dynes. And spraying a Jinxi stabilizer to lock surface polar groups. When the anti-counterfeiting film is uncovered, a high-contrast yin-yang complementary anti-counterfeiting pattern is formed, the anti-counterfeiting effect is excellent, the corona stability is good, and the shelf life is long

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of packaging anti-counterfeiting materials, in particular to a corona differential treatment anti-removing trace opening pull thread and a preparation method thereof. BACKGROUND

[0002] The opening pull thread is widely used in the fields of express package, food package, medicine package, electronic product package and the like as a disposable anti-opening mark. In order to enhance the anti-counterfeiting function, the prior art forms an anti-counterfeiting pattern by coating a non-removing coating layer on a base film, utilizes the surface tension difference generated by corona treatment to make the adhesion of ink different in different areas, and thus forms an anti-counterfeiting pattern when being removed. A typical technical solution is to pre-coat a non-removing coating layer of the designed anti-counterfeiting pattern before corona processing, and the formula of the non-removing coating layer is 20% to 30% of epoxy resin, 2% to 4% of dispersing agent, 1% of wetting agent and 70% to 80% of No. 120 gasoline. After the corona treatment of the base film, the corona value of the coating layer part is 30 dynes, and the corona value of the non-coating layer part is 40 dynes, and the difference between the two is 10 dynes.

[0003] However, the prior art has the following problems: first, the corona value difference is small, only 10 dynes, which leads to an insignificant difference in ink adhesion, low contrast of the anti-counterfeiting pattern, blurred boundary and unsatisfactory anti-counterfeiting effect; second, the single-layer coating structure is difficult to accurately control the corona performance of different areas, and the uneven thickness of the coating layer affects the pattern definition; third, there is a lack of corona stability control measures, the corona value decays quickly with time, the product shelf life is short, and the anti-counterfeiting effective period is limited; fourth, the anti-counterfeiting dimension is single, relying only on visual anti-counterfeiting, lacking multiple verification means, and being easy to be imitated. Therefore, it is necessary to develop an opening pull thread with larger corona difference, better anti-counterfeiting effect and better stability and a preparation method thereof. SUMMARY

[0004] The present application aims to provide a corona differential treatment anti-removing trace opening pull thread and a preparation method thereof to solve the problems existing in the prior art.

[0005] The present application provides a corona differential treatment anti-removing trace opening pull thread, which comprises, from bottom to top, in sequence: a base film layer, the base film layer being a biaxially oriented polypropylene film or a polyethylene terephthalate film with a thickness of 25 microns to 50 microns; a corona shielding layer, the corona shielding layer being coated on the upper surface of the base film layer in full width, and the formula of the corona shielding layer comprises, by weight percentage, 35% to 45% of silicone resin, 5% to 8% of nano-silicon dioxide with a particle size of 20 nanometers to 50 nanometers, 3% to 5% of zinc stearate, 1% to 2% of coupling agent KH-550, and the balance of No. 120 solvent oil; the dry coating thickness of the corona shielding layer is 1.5 microns to 2.5 microns; The selective corona enhancement layer is coated on the preset anti-fake pattern area on the surface of the corona shielding layer in a patterned manner, and the formulation of the selective corona enhancement layer comprises, by weight percentage, 25% to 35% of hydroxy acrylic resin, 8% to 12% of isocyanate curing agent, 5% to 8% of maleic anhydride grafted polypropylene, 3% to 5% of nano-aluminum oxide with a particle size of 30 nanometers to 60 nanometers, 0.5% to 1% of leveling agent, and the rest of mixed solvent of ethyl acetate and butyl acetate, with a mass ratio of ethyl acetate to butyl acetate of 3:1; the dry coating thickness of the selective corona enhancement layer is 3 micrometers to 5 micrometers; The adhesive layer is coated on the surface of the selective corona enhancement layer and the corona shielding layer; The printing ink layer is coated on the surface of the adhesive layer; The corona value of the selective corona enhancement layer covering area is 48 dynes to 52 dynes, the corona value of the corona shielding layer covering area is 25 dynes to 28 dynes, and the difference between the corona values of the two areas is 20 dynes to 27 dynes.

[0006] Through the gradient corona treatment of the above technical solution, the corona value of the selective corona enhancement layer covering area reaches 48 dynes to 52 dynes, the corona value of the corona shielding layer covering area is 25 dynes to 28 dynes, and the difference between the corona values of the two areas reaches 20 dynes to 27 dynes. This large corona difference leads to a significant difference in the adhesion of the ink in different areas, and when the pull line body and the adherend surface are peeled off, clear complementary anti-fake patterns are formed, realizing a high-contrast anti-peeling effect. The corona value difference is 2 to 2.7 times that of the prior art, the anti-fake pattern has high contrast, clear boundaries, and high recognition rate, and through the corona stabilizer treatment, the corona value attenuation rate is less than 5% in 6 months, and the product stability is significantly improved.

[0007] Further, the hydroxyl value of the hydroxy acrylic resin is 80 mg KOH / g to 120 mg KOH / g; and the grafting rate of the maleic anhydride grafted polypropylene is 0.5% to 1.2%.

[0008] Further, the surface roughness Ra value of the selective corona enhancement layer covering area is 150 nanometers to 250 nanometers; and the surface roughness Ra value of the corona shielding layer covering area is 50 nanometers to 100 nanometers.

[0009] Further, the preset anti-fake pattern is one or a combination of two or more of a two-dimensional code, a bar code, a word, a company logo, or a pattern.

[0010] The preparation method of the corona differentiated anti-peeling and anti-removing sealable pull line comprises the following steps: Step one, a biaxially stretched polypropylene film or a polyethylene terephthalate film is used as a base film layer, and the surface dust and static electricity are removed through a dust removal roller and an electrostatic elimination device; Step two, coat the whole surface of the base film layer with a corona shielding layer coating, the formula of the corona shielding layer coating is composed of 35% to 45% of silicone resin, 5% to 8% of nano silicon dioxide with a particle size of 20 nanometers to 50 nanometers, 3% to 5% of zinc stearate, 1% to 2% of coupling agent KH-550, and the rest of 120# solvent oil; adopt the anilox roll coating method, the anilox roll line number is 180 lines per inch to 220 lines per inch, and the wet coating thickness is 3 microns to 5 microns; after coating, dry at 80 degrees Celsius to 90 degrees Celsius for 15 seconds to 20 seconds, and get a dry coating thickness of 1.5 microns to 2.5 microns of the corona shielding layer; Step three, pattern coating the selective corona enhancement layer coating on the surface of the corona shielding layer, the formula of the selective corona enhancement layer coating is composed of 25% to 35% of hydroxy acrylic resin, 8% to 12% of isocyanate curing agent, 5% to 8% of maleic anhydride grafted polypropylene, 3% to 5% of nano alumina with a particle size of 30 nanometers to 60 nanometers, 0.5% to 1% of leveling agent, and the rest of mixed solvent of ethyl acetate and butyl acetate with a mass ratio of 3 to 1; adopt the laser engraved microporous roller gravure printing method to coat in the preset anti-fake pattern area, the mesh depth is 18 microns to 25 microns, the mesh density is 60 lines per centimeter to 80 lines per centimeter, and the wet coating thickness is 6 microns to 10 microns; after coating, dry at 70 degrees Celsius to 80 degrees Celsius for 10 seconds to 15 seconds, and get a dry coating thickness of 3 microns to 5 microns of the selective corona enhancement layer; Step four, the area coated with the selective corona enhancement layer is subjected to the first stage pre-corona treatment, the corona power is 1.2 kilowatts to 1.5 kilowatts, the processing speed is 60 meters per minute to 80 meters per minute, and the electrode spacing is 1.5 millimeters to 2.0 millimeters, so that the corona value of the selective corona enhancement layer covered area reaches 48 dynes to 52 dynes; Step five, the entire surface is subjected to the second stage differential corona treatment, 0.3 kilowatts to 0.5 kilowatts of corona power is applied to the selective corona enhancement layer covered area, 0.8 kilowatts to 1.2 kilowatts of corona power is applied to the corona shielding layer covered area, the electrode spacing is 1.5 millimeters to 2.0 millimeters, and the processing speed is 60 meters per minute to 80 meters per minute, so that the selective corona enhancement layer covered area maintains a corona value of 48 dynes to 52 dynes, and the corona value of the corona shielding layer covered area reaches 25 dynes to 28 dynes; Step six, within 3 seconds to 5 seconds after completing step five, spray the corona stabilizer, the formula of the corona stabilizer is composed of 5% of polyvinyl alcohol, 2% of sodium chloride, and 93% of deionized water; the spraying amount is 0.5 grams per square meter to 0.8 grams per square meter; after spraying, dry at 50 degrees Celsius to 60 degrees Celsius for 8 seconds to 12 seconds; Step seven, after winding, aging in an environment with a temperature of 23 degrees Celsius plus or minus 2 degrees Celsius and a relative humidity of 50% plus or minus 5% for 24 hours to 48 hours; Step eight, coating an adhesive layer on the corona treated surface, with a coating amount of 20 grams per square meter to 30 grams per square meter; Step nine, printing an ink layer on the surface of the adhesive layer; Step ten, slitting and cutting into a tear-off pull line with a width of 5 millimeters to 25 millimeters.

[0011] Further, in step three, the roller material of the laser-engraved micro-hole roller cylinder intaglio is copper-based chromium-plated material, and the mesh hole shape is inverted conical.

[0012] Further, in step six, the polymerization degree of polyvinyl alcohol is 1700 to 2000; the corona stabilizer is sprayed through an ultrasonic atomizing nozzle, and the atomized particle size is 10 microns to 30 microns.

[0013] Further, in step four, a segmented electrode control system is used to selectively corona treat the selective corona enhancement layer coverage area, and precise positioning is achieved through a tension sensor and a pattern recognition system.

[0014] Further, in step five, a power zoning control module is used to apply different corona powers to different areas, and the power zoning control module controls the corona power of each area according to the pattern positioning information in step four.

[0015] The beneficial effects of the present application are: First, the present application realizes a difference of 20 to 27 dynes between the selective corona enhancement layer area and the corona shielding layer area through a double-layer coating system combined with gradient corona treatment, which is 2 to 2.7 times that of the prior art. The large corona difference makes the peel force of the ink in the high corona area greater than 10 N / 25mm, and the peel force in the low corona area is 1.5 N / 25mm to 3 N / 25mm, with a significant difference in adhesion. When peeled off, a positive anti-fake pattern is retained on the pull line body, and a negative anti-fake pattern is formed on the adherend surface, which are complementary to each other, with high pattern contrast and clear and sharp boundaries. The two-dimensional code recognition rate in Example 1 reaches 97%, which is much higher than 78% of Comparative Example 1 of the prior art, and the anti-fake effect is significantly better than the prior art.

[0016] Secondly, the present application adopts a double-layer structure of a corona shielding layer as a bottom layer and a selective corona enhancement layer as a surface layer. The bottom shielding layer contains silicone resin and nano-silicon dioxide to form a low surface energy coating, thereby reducing the sensitivity of the area to corona treatment. The surface enhancement layer contains hydroxyl acrylic resin, maleic anhydride grafted polypropylene and nano-aluminum oxide to improve the corona sensitivity of the area. The two layers of coating work together to accurately control the corona performance of different areas. At the same time, the nano-materials form a micro-nano structure in the coating. The surface roughness Ra value of the enhancement layer area is 150-250 nm, and the shielding layer area is 50-100 nm. The difference in surface morphology not only enhances the mechanical anchoring force of the ink, but also provides a tactile anti-counterfeiting and microscopic anti-counterfeiting dimension. Combined with visual anti-counterfeiting and instrument detection anti-counterfeiting, a multi-layer anti-counterfeiting system is formed, and the anti-counterfeiting level is significantly higher than the single visual anti-counterfeiting of the prior art.

[0017] Thirdly, the present application sprays a corona stabilizer within 3-5 seconds after completing the gradient corona treatment. The polyvinyl alcohol and sodium chloride in the stabilizer can lock the surface polarity groups to prevent the decay of the corona value. The test results of Example 1 show that after 6 months of storage at room temperature, the corona value of the enhancement layer area treated with the stabilizer decreases from 50 dynes to 48 dynes, with an attenuation rate of only 4%; the shielding layer area decreases from 26 dynes to 25 dynes, with an attenuation rate of 3.8%. In Comparative Example 2, the product without stabilizer has a corona value decay rate of 24% after 6 months, which is 6 times that of the present application. The significant improvement in corona stability extends the shelf life of the product from 6-9 months of the prior art to more than 18 months, significantly extends the effective period of anti-counterfeiting, reduces the risk of product failure, and improves the practical value and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only a part of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Fig. 1 Figure 1 is a schematic diagram of the unsealing pull wire structure of the present application; Fig. 2 Figure 2 is a schematic diagram of the microstructure of the double-layer coating and the difference in corona value of the present application; Fig. 3 Figure 3 is a flow chart of the key steps of the preparation method of the present application; Fig. 4 Figure 4 is a schematic diagram of the anti-uncovering trace effect of the present application. DETAILED DESCRIPTION

[0020] The application will be described in detail below with reference to the drawings and specific embodiments. It should be noted that the following embodiments are the best, preferred embodiments, and other alternative embodiments can also be implemented by those skilled in the art for some known technologies; and the drawings are only used to more specifically describe the embodiments, and are not intended to specifically limit the application.

[0021] It should be noted that in the specification, "one embodiment", "embodiment", "exemplary embodiment", "some embodiments" and the like indicate that the described embodiment can include a specific feature, structure or property, but not necessarily every embodiment includes the specific feature, structure or property. In addition, when a specific feature, structure or property is described in combination with an embodiment, it should be within the knowledge of those skilled in the related art to implement such a feature, structure or property in combination with other embodiments, whether or not it is explicitly described.

[0022] Generally, the terms can be understood at least in part from the context of their usage. For example, depending at least in part upon the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular or can be used to describe combinations of features, structures, or characteristics. In addition, the term "based on" can be understood as not necessarily requiring a set of exclusive factors, but, alternatively, allowing for existence of additional or even unrecited factors, depending at least in part on the context.

[0023] Referring to Figs. 1 to 4 as shown I. Overview of the overall technical solution The application provides a corona differential processing anti-removing trace and seal-off pull wire and a preparation method thereof. The seal-off pull wire forms a high and low corona value difference area on the surface of the pull wire by constructing a double-layer anti-removing coating system on the base film in combination with gradient corona processing technology, and the difference value reaches more than 20 dynes. When the pull wire is removed, different adhesion of ink is caused by the corona value difference of different areas, so that a positive and negative complementary anti-fake pattern is formed on the pull wire body and the surface of the adherend respectively, and the anti-removing trace anti-fake function is realized.

[0024] The seal-off pull wire of the application comprises, from bottom to top, a base film layer, a corona shielding layer, a selective corona enhancement layer, an adhesive layer and a printing ink layer.

[0025] II. Structure and material composition of each layer 1. Base film layer The base film layer is selected from biaxially oriented polypropylene film or polyethylene terephthalate film, and the thickness is 25 microns to 50 microns. Preferably, the thickness of the biaxially oriented polypropylene film is 38 microns. The initial surface tension value of the base film layer is 32 dynes to 36 dynes.

[0026] 2. Corona shield layer The corona shield layer is coated on the upper surface of the base film layer, which is full-width coating. The function of this coating is to reduce the corona sensitivity of the surface of the base film, so that this area maintains a lower corona value during subsequent corona treatment.

[0027] The formula composition of the corona shield layer is as follows in terms of weight percentage: Silicone resin: 35% to 45% Nano-silicon dioxide: 5% to 8%, particle size 20 nm to 50 nm Zinc stearate: 3% to 5% Coupling agent KH-550: 1% to 2% 120# solvent oil: balance The preferred formula is: silicone resin 40%, nano-silicon dioxide 6.5%, zinc stearate 4%, coupling agent KH-550 1.5%, 120# solvent oil 48%.

[0028] The corona shield layer is coated by using an anilox roll coating method, the anilox roll line number is 180 lines per inch to 220 lines per inch, preferably 200 lines per inch. The wet coating thickness is controlled at 3 microns to 5 microns, and the dry coating thickness is 1.5 microns to 2.5 microns. After coating, it immediately enters the drying area, the drying temperature is 80 degrees Celsius to 90 degrees Celsius, the drying time is 15 seconds to 20 seconds, and the oven length is 8 meters to 12 meters.

[0029] 3. Selective corona enhancement layer The selective corona enhancement layer is coated by using a patterned coating method, only in the preset anti-counterfeiting pattern area. The function of this coating is to improve the sensitivity of this area to corona treatment, so that it reaches a significantly higher corona value than the shield layer area after corona treatment.

[0030] The formula composition of the selective corona enhancement layer is as follows in terms of weight percentage: Hydroxy acrylic resin: 25% to 35%, hydroxyl value 80 mg KOH / g to 120 mg KOH / g Isocyanate curing agent: 8% to 12% Maleic anhydride grafted polypropylene: 5% to 8%, grafting rate 0.5% to 1.2% Nano-alumina: 3% to 5%, particle size 30 nm to 60 nm Leveling agent: 0.5% to 1% Mixed solvent of ethyl acetate and butyl acetate: balance, mass ratio 3:1 The preferred formula is: hydroxy acrylic resin 30%, isocyanate curing agent 10%, maleic anhydride grafted polypropylene 6.5%, nano-alumina 4%, leveling agent 0.8%, mixed solvent 48.7%.

[0031] The selective corona enhancement layer is coated by laser-engraved micro-hole roller gravure printing. The roller is made of copper-based chromium-plated material, and the micro-hole mesh is formed by laser engraving corresponding to the anti-counterfeiting pattern. The mesh depth is 18-25 microns, preferably 22 microns. The mesh density is 60-80 lines per centimeter, preferably 70 lines per centimeter. The printing speed is 50-80 meters per minute.

[0032] The wet film thickness of the coated enhancement layer is 6-10 microns, and the dry film thickness is 3-5 microns. The drying temperature is 70-80 degrees Celsius, and the drying time is 10-15 seconds.

[0033] 4. Adhesive layer and printed ink layer The adhesive layer uses pressure-sensitive adhesive, with a coating amount of 20-30 grams per square meter. The printed ink layer uses water-based or solvent-based ink, and is completed by flexographic printing or gravure printing.

[0034] III. Gradient corona treatment process Gradient corona treatment is one of the core technologies of the present application, and is divided into three stages of treatment.

[0035] First stage: pre-corona treatment Pre-corona treatment is only carried out on the area coated with the selective corona enhancement layer. A segmented electrode control system is used to achieve selective corona through mask or program control.

[0036] Process parameters are as follows: Corona power: 1.2-1.5 kW, preferably 1.35 kW Treatment speed: 60-80 meters per minute, preferably 70 meters per minute Electrode spacing: 1.5-2.0 mm, preferably 1.8 mm Electrode width: customized according to pattern width, with an accuracy of ±0.1 mm Number of treatments: 1-2 times Target corona value: 48-52 dynes Pre-corona treatment significantly increases the surface polarity of the enhancement layer area, forming a large number of hydroxyl, carbonyl and carboxyl groups.

[0037] Second stage: differential corona treatment Differential corona treatment is carried out on the entire web, but different corona powers are applied to different areas, forming a gradient of corona values.

[0038] For the enhancement layer area that has been pre-corona treated: Corona power: 0.3-0.5 kW, preferably 0.4 kW Effect: maintain and stabilize the existing high corona value Final corona value: 48 dynes to 52 dynes, preferably 50 dynes For the area with only the shielding layer: Corona power: 0.8 kW to 1.2 kW, preferably 1.0 kW Purpose: to perform a moderate corona treatment on the surface of the shielding layer Final corona value: 25 dynes to 28 dynes, preferably 26 dynes Through the above two-stage processing, a corona value difference of 20 dynes to 25 dynes, preferably 24 dynes, is formed between the reinforcing layer area and the shielding layer area.

[0039] The processing speed is maintained at 60 meters per minute to 80 meters per minute, and the electrode spacing is 1.5 mm to 2.0 mm.

[0040] Third stage: stabilization treatment Within 3 seconds to 5 seconds after completing the differential corona treatment, a corona stabilizer is sprayed on the surface of the film to lock the surface polar groups and prevent the corona value from decaying.

[0041] The corona stabilizer formula is as follows by weight percentage: Polyvinyl alcohol: 5%, degree of polymerization 1700 to 2000 Sodium chloride: 2% Deionized water: 93% The stabilizer is sprayed through an ultrasonic atomizing nozzle with an atomized particle size of 10 microns to 30 microns. The spraying amount is 0.5 grams per square meter to 0.8 grams per square meter, preferably 0.65 grams per square meter. After spraying, it immediately enters the drying area with a drying temperature of 50 degrees Celsius to 60 degrees Celsius and a drying time of 8 seconds to 12 seconds.

[0042] Four, complete preparation method Step one: substrate preparation The biaxially oriented polypropylene film or polyethylene terephthalate film is unwound, and the surface dust and static electricity are removed through dust removal rollers and static electricity elimination devices. The tension is controlled at 80 N to 120 N.

[0043] Step two: coating the corona shielding layer Add 40 parts of silicone resin, 6.5 parts of nano-silicon dioxide, 4 parts of zinc stearate, and 1.5 parts of coupling agent KH-550 to the mixing tank, and stir for 10 minutes to 15 minutes. Add 48 parts of 120# solvent oil, continue to stir for 20 minutes to 30 minutes, and make the nano-silicon dioxide fully dispersed. The mixed solution is filtered through a 200 mesh filter screen and transferred to the coating machine tank.

[0044] The anilox roller coating method is used, the anilox roller line number is 200 lines per inch, and the coating speed is 70 meters per minute. The wet coating thickness is controlled at 4 microns. After coating, the film enters the drying oven, which is divided into three sections, with temperatures of 75 degrees Celsius, 85 degrees Celsius and 90 degrees Celsius respectively, and the total drying time is 18 seconds. The dried coating thickness is 2 microns, and the surface is uniform without spots.

[0045] Step three: patterned coating of the selective corona enhancement layer Add 30 parts of hydroxy acrylic resin, 6.5 parts of maleic anhydride grafted polypropylene, 4 parts of nano aluminum oxide and 0.8 parts of leveling agent into a mixing tank, add 36.5 parts of ethyl acetate and 12.2 parts of butyl acetate, and stir for 30 minutes to 40 minutes. When in use, add 10 parts of isocyanate curing agent, stir quickly for 5 minutes to 8 minutes, and the mixing liquid has a pot life of 4 hours to 6 hours.

[0046] A laser engraved micro-hole roller cylinder gravure printing machine is used, and the roller cylinder has been engraved with a corresponding network hole of the anti-counterfeiting pattern. The network hole depth is 22 microns, and the density is 70 lines per centimeter. The printing speed is 70 meters per minute, the doctor blade angle is 55 degrees to 65 degrees, and the doctor blade pressure is 0.3 megapascals to 0.5 megapascals.

[0047] After printing, the film enters the drying oven, and the drying temperature is 75 degrees Celsius, and the drying time is 12 seconds. The dried enhancement layer thickness is 4 microns, the pattern edge is clear, and the overlaying accuracy is plus or minus 0.1 millimeter.

[0048] Step four: first stage pre-corona treatment The film enters the first corona treatment station. The treatment station is equipped with a segmented electrode control system, which realizes accurate positioning through a tension sensor and a pattern recognition system.

[0049] The corona electrode width corresponds to the enhancement layer pattern width, and the electrode spacing is set to 1.8 millimeters. The corona power is set to 1.35 kilowatts, and the processing speed is 70 meters per minute. The electrodes discharge the enhancement layer area, and the processing time is about 0.4 seconds to 0.6 seconds per pattern unit.

[0050] Immediately after treatment, the online corona value detection device is used for detection to ensure that the corona value of the enhancement layer area reaches 48 dynes to 52 dynes.

[0051] Step five: second stage differential corona treatment The film continues to enter the second corona treatment station. The treatment station uses full-width electrodes, but realizes differential treatment through power zoning control.

[0052] The control system applies 0.4 kilowatts of power to the enhancement layer area and 1.0 kilowatts of power to the shielding layer area according to the pattern positioning information of the first stage. The electrode spacing is 1.8 millimeters, and the processing speed is 70 meters per minute.

[0053] After treatment, the corona value of the two areas is detected simultaneously by an online double-channel corona value detection system. The area of the reinforcing layer is maintained at 50 dynes plus or minus 2 dynes, and the area of the shielding layer reaches 26 dynes plus or minus 2 dynes, with a difference of 24 dynes.

[0054] Step six: spraying of corona stabilizer Four seconds after the completion of the second-stage corona treatment, the film enters the stabilizer spraying area. The stabilizer formula is 5 parts of polyvinyl alcohol, 2 parts of sodium chloride, and 93 parts of deionized water. The polyvinyl alcohol is completely dissolved by stirring and heating to 70-80°C, and then cooled to room temperature for standby.

[0055] The stabilizer is sprayed through an ultrasonic atomizing nozzle with a frequency of 40-60 kHz and a particle size of 20 microns. The spraying amount is accurately controlled at 0.65 g / m2 by a flow control valve. After spraying, the film enters the drying area at a temperature of 55°C for 10 seconds.

[0056] Step seven: winding and aging The treated film is cooled to room temperature by a cooling roller and then wound. The winding tension is 60-80 N, and the winding diameter is controlled at 600-800 mm. After winding, the film is aged in an environment with a temperature of 23°C plus or minus 2°C and a relative humidity of 50% plus or minus 5% for 24-48 hours to completely cure the coating.

[0057] Step eight: adhesive layer coating The aged film is unwound and coated with pressure-sensitive adhesive on the side treated by corona. The pressure-sensitive adhesive is an acrylate-based pressure-sensitive adhesive with a solid content of 45-55%. The coating method is comma blade coating or micro-recess coating, and the coating amount is 25 g / m2. After coating, it is dried at 120°C for 15-20 seconds.

[0058] Step nine: printing of ink layer An ink layer is applied on the adhesive layer surface by flexographic printing or gravure printing. The ink can be single-color or multi-color, and can contain text, patterns, barcodes, and QR codes. The printing speed is 80-120 m / min. After printing, it is cured by UV light or dried by hot air.

[0059] Step ten: slitting and cutting The printed film is cut into the required width by a slitting machine, usually 300-1500 mm. Then it is cut into a thin strip by a cutting machine to form a tear-off pull tab, with a width of 5-25 mm. The cutting accuracy is plus or minus 0.1 mm, and the edge is free of burrs.

[0060] Step eleven: finished product winding The cut, unpacked, and pulled threads are then wound into finished rolls, with each roll ranging from 3,000 to 10,000 meters in length. The finished product needs to be covered with release paper or wound directly. After packaging, store in a cool, dry place, away from direct sunlight.

[0061] V. Anti-tampering and trace-retention mechanism When the user peels off the pull cord, the ink in the reinforcing layer area, with a corona value as high as 50 dynes, forms a strong adhesion between the ink and the base film, firmly adhering to the pull cord itself. However, the shielding layer area, with a corona value of only 26 dynes, has a weaker adhesion between the ink and the base film, leaving ink residue on the surface of the object being adhered to.

[0062] Therefore, after peeling off the backing, a positive anti-counterfeiting pattern appears on the pull cord itself, corresponding to the area coated with the reinforcing layer; a negative anti-counterfeiting pattern appears on the surface of the object being adhered to, corresponding to the area covered by the shielding layer. The two patterns complement each other, creating an anti-tampering and traceable anti-counterfeiting effect.

[0063] Because the difference in corona value is as high as 24 dynes, which is much greater than the 10 dynes of the existing technology, the pattern contrast is significantly improved, the boundaries are clear and sharp, and the anti-counterfeiting effect is excellent.

[0064] Example Example 1: QR code anti-counterfeiting pull tab Step 1: Substrate Selection The film used is a biaxially oriented polypropylene film with a thickness of 38 micrometers, a width of 1300 mm, and a surface tension of 34 dynes.

[0065] Step 2: Prepare the corona shielding layer coating Take 40g of methyl silicone resin, 6.5g of fumed silica (30nm particle size), 4g of zinc stearate, and 1.5g of coupling agent KH-550, add them to a mixing tank, and stir for 12 minutes. Add 48g of No. 120 solvent oil and continue stirring for 25 minutes. Filter the solution twice through a 200-mesh filter and transfer it to a coating tank.

[0066] Step 3: Applying the shielding layer An anilox roller coater was used, with an anilox roller line count of 200 lines per inch and a roller diameter of 120 mm. The coating speed was 70 meters per minute, and the coating tension was 100 Newtons. The wet coating thickness was 4 micrometers.

[0067] The film enters a three-stage drying tunnel: the first stage is 3 meters long and has a temperature of 75 degrees Celsius; the second stage is 4 meters long and has a temperature of 85 degrees Celsius; and the third stage is 3 meters long and has a temperature of 90 degrees Celsius. The total drying time is 18 seconds. After drying, the coating thickness is 2 micrometers, and the surface is smooth and free of particles.

[0068] Step 4: Prepare the corona-reinforced coating Into a mixing jar, add 30 grams of hydroxyl acrylate resin with hydroxyl value of 100 mg KOH per gram, 6.5 grams of maleic anhydride grafted polypropylene with grafting rate of 0.8%, 4 grams of nano alumina with particle size of 45 nanometers, and 0.8 grams of polyether modified silicone leveling agent. Add 36.5 grams of ethyl acetate and 12.2 grams of butyl acetate, and stir for 35 minutes until the solution is clear. Before use, add 10 grams of HDI trimer type isocyanate curing agent, stir quickly for 6 minutes, and use the mixture within 4 hours.

[0069] Fifth step: patterned coating of the enhancement layer A laser engraved gravure printing machine is used, with a plate roller diameter of 280 millimeters and a chrome-plated copper roller body. The plate roller is engraved with a two-dimensional code pattern, with a two-dimensional code size of 10 millimeters by 10 millimeters and a module size of 0.4 millimeters by 0.4 millimeters, consisting of 25 by 25 modules. The screen cell depth is 22 micrometers, and the screen cell shape is inverted conical with an opening diameter of 0.38 millimeters.

[0070] The printing speed is 70 meters per minute, the doctor blade angle is 60 degrees, the doctor blade material is Swedish SANDVIK steel, and the doctor blade pressure is 0.4 megapascals. After printing, the wet film thickness is 8 micrometers.

[0071] Enter the drying oven, with a temperature of 75 degrees Celsius, a hot air speed of 8 meters per second, and a drying time of 12 seconds. After drying, the film thickness is 4 micrometers, the pattern edges are clear, and the two-dimensional code module boundary error is less than 0.05 millimeters.

[0072] Sixth step: first stage pre-corona The film enters the first corona treatment station, which is equipped with segmented electrodes with a width of 12 millimeters, 100 groups of electrodes that can be independently controlled. The two-dimensional code position is located by a pattern recognition camera, and the control system starts the electrodes at the corresponding position.

[0073] The electrode material is stainless steel coated with ceramic, and the electrode spacing is 1.8 millimeters. The corona power is 1.35 kilowatts, the frequency is 15 kilohertz, and the processing speed is 70 meters per minute. The processing time for each two-dimensional code pattern is about 0.5 seconds.

[0074] After processing, the two-dimensional code pattern area corona value reaches 50 dynes through contact corona test pen detection.

[0075] Seventh step: second stage differential corona The film enters the second corona treatment station, which uses full-width electrodes with a width of 1400 millimeters. The electrodes achieve power differentiation through a zone power control module.

[0076] The control system receives the pattern positioning data from the first stage and applies a power of 0.4 kilowatts at the corresponding position of the two-dimensional code pattern and a power of 1.0 kilowatts at the background area. The electrode spacing is 1.8 millimeters, and the processing speed is 70 meters per minute.

[0077] After treatment, the film was tested by an on-line dual-probe corona tester. The first probe tested the area of the QR code and showed 50 dynes; the second probe tested the background area and showed 26 dynes. The difference between the two areas was 24 dynes.

[0078] Eighth step: spraying stabilizer Prepare the stabilizer: take 5 grams of polyvinyl alcohol with a degree of polymerization of 1800 and add it to 93 grams of deionized water. Heat to 75 degrees Celsius and stir until completely dissolved. Add 2 grams of sodium chloride and stir until dissolved. Cool to 25 degrees Celsius and reserve.

[0079] Four seconds after the completion of the second-stage corona, the film enters the spraying area. The stabilizer is atomized by an ultrasonic atomizing nozzle with a frequency of 50 kHz, and the atomized particle size is 20 microns. The spraying flow rate is controlled at a spraying amount of 0.65 grams per square meter.

[0080] Immediately after spraying, the film enters the drying area, with a temperature of 55 degrees Celsius and a hot air speed of 5 meters per second, and a drying time of 10 seconds. After drying, the surface is free of water marks and spots.

[0081] Ninth step: aging The film is wound at a tension of 70 Newtons, with a roll diameter of 700 millimeters. It is aged in a constant temperature and humidity chamber for 36 hours, at a temperature of 23 degrees Celsius and a relative humidity of 50%.

[0082] Tenth step: applying pressure-sensitive adhesive After aging, the film is unwound and coated with an acrylate pressure-sensitive adhesive on the corona-treated side. The pressure-sensitive adhesive has a solid content of 50% and a viscosity of 8000-12000 mPa·s.

[0083] A comma doctor blade is used for coating, with a coating amount of 25 grams per square meter and a coating speed of 80 meters per minute. After coating, the film is dried in a three-stage oven, with temperatures of 100, 120, and 130 degrees Celsius respectively, and a total drying time of 18 seconds.

[0084] Eleventh step: printing ink Black ink is printed on the pressure-sensitive adhesive side using a gravure printing machine. The ink is water-based, with a solid content of 40%. The printing speed is 100 meters per minute, and the printing pressure is 0.5-0.7 MPa. After printing, the film is dried with hot air at 80 degrees Celsius for 10 seconds.

[0085] Twelfth step: slitting and cutting The printed film is cut into a width of 500 millimeters by a slitting machine, and then cut into a width of 12 millimeters by a precision cutting machine. The cutting blade is a round knife with a blade angle of 30 degrees, and the cutting speed is 120 meters per minute. The cutting edge is neat and free of burrs.

[0086] Thirteenth step: finished product packaging The cut and opened pull-tab is 5000 meters in length per roll, coated with 40 grams per square meter of release paper, and then rolled up. The single roll is packaged with polyethylene film and stored in a cool and dry warehouse.

[0087] Performance test results: Corona value test: 50 dynes in the QR code area, 26 dynes in the background area, and a difference of 24 dynes Ink adhesion test: the peeling force in the QR code area is greater than 10 N / 25 mm, and the peeling force in the background area is 2-3 N / 25 mm Anti-removal mark effect: after the pull-tab is removed, the black modules of the QR code remain on the pull-tab body, and the white module ink is transferred to the adherend, forming a clear complementary pattern QR code recognition rate: the QR code remaining on the pull-tab body can be scanned and recognized, with a success rate of 97% Corona stability: after 6 months of storage at room temperature, the corona value in the QR code area is 48 dynes, with a decay of 4%; the background area is 25 dynes, with a decay of 3.8% Example 2: Company logo anti-fake opening pull-tab First step: substrate selection A polyethylene terephthalate film with a thickness of 50 microns and a width of 1000 mm is selected, and the surface tension is 35 dynes.

[0088] Second step: preparation of shielding layer coating Take 42 grams of hydroxyl-terminated polydimethylsiloxane, 7 grams of hydrolyzed nano-silicon dioxide with a particle size of 25 nanometers, 3.5 grams of zinc stearate, and 2 grams of coupling agent KH-550, and stir in a mixing tank for 15 minutes. Add 45.5 grams of 120# solvent oil and continue stirring for 30 minutes. After filtering the solution, transfer it to a coating machine.

[0089] Third step: coating the shielding layer Use a screen roller to coat, with a screen roller line number of 180 lines per inch. The coating speed is 60 meters per minute, and the wet coating thickness is 3.5 microns.

[0090] The drying temperature is 70 degrees Celsius in the first section, 80 degrees Celsius in the second section, and 85 degrees Celsius in the third section, with a total drying time of 20 seconds. The dry coating thickness is 1.8 microns.

[0091] Fourth step: preparation of the reinforcing layer coating Take 28 grams of hydroxyl acrylate resin with a hydroxyl value of 90 mg KOH / g, 7 grams of maleic anhydride grafted polypropylene with a grafting rate of 1.0%, 4.5 grams of nano-aluminum oxide with a particle size of 35 nanometers, and 1 gram of leveling agent, and add them to a mixing tank. Add 37.5 grams of ethyl acetate and 12.5 grams of butyl acetate, and stir for 40 minutes. Before use, add 9.5 grams of toluene diisocyanate curing agent and stir for 8 minutes.

[0092] Fifth step: patterned coating of the enhancement layer The laser engraved gravure printing company logo pattern, logo size 30mm by 15mm, contains Chinese and English words and graphics. The cell depth is 20 microns, and the density is 65 lines per centimeter.

[0093] The printing speed is 60 meters per minute, the doctor blade angle is 55 degrees, and the pressure is 0.35 megapascals. The drying temperature is 70 degrees Celsius, and the time is 15 seconds. The dry film thickness is 3.5 microns.

[0094] Sixth step: first stage pre-corona A segmented electrode with a width of 32 mm is used, and the electrode spacing is 1.6 mm. The corona power is 1.4 kW, and the processing speed is 60 meters per minute. The logo pattern area reaches a corona value of 51 dynes.

[0095] Seventh step: second stage differential corona The logo area is applied with a power of 0.35 kW, and the background area is applied with a power of 0.9 kW. The electrode spacing is 1.6 mm, and the processing speed is 60 meters per minute. The logo area is maintained at 51 dynes, the background area reaches 27 dynes, and the difference is 24 dynes.

[0096] Eighth step: spray stabilizer Stabilizer formula: polyvinyl alcohol 5 grams, sodium chloride 2 grams, deionized water 93 grams. Spray amount 0.7 grams per square meter. Drying temperature 58 degrees Celsius, time 11 seconds.

[0097] Ninth step: aging Tension 85 Newtons winding, aging 48 hours, temperature 23 degrees Celsius, humidity 50%.

[0098] Tenth step: coating pressure-sensitive adhesive Coating acrylate pressure-sensitive adhesive, coating amount 28 grams per square meter. Drying temperature 110 degrees Celsius to 125 degrees Celsius, time 20 seconds.

[0099] Eleventh step: printing ink Flexographic printing of blue and white ink to form a blue background with white lettering effect. Printing speed 90 meters per minute. Ultraviolet light curing, power 120 watts per centimeter.

[0100] Twelfth step: slitting and cutting Slitting into a width of 800 mm, and cutting into a width of 15 mm for the tear-off pull tab. The cut edge is flat and has no curling.

[0101] Performance test results: Corona value: logo area 51 dynes, background 27 dynes, difference 24 dynes Anti-peeling and marking effect: after peeling, the logo pattern is clearly identifiable, and the letter and graphic boundaries are sharp Weatherability test: after 72 hours of aging at 85 degrees Celsius, corona value decay 3.2% Adhesion strength: initial tack 12 Newton per 25 mm, hold tack 24 hours no fall off Example 3: Anti-counterfeit pattern tear-off pull-tab Step 1: Substrate selection A biaxially stretched polypropylene film with thickness of 32 microns was selected, with a width of 1500 mm.

[0102] Step 2: Formulation of the barrier layer coating Methylphenyl silicone resin 38 grams, nano-silica with particle size of 40 nm 6 grams, zinc stearate 4.5 grams, coupling agent KH-550 1.2 grams, 120# solvent oil 50.3 grams, stirring and mixing.

[0103] Step 3: Coating the barrier layer Anilox roll 210 lines per inch, coating speed 75 meters per minute, wet coating thickness 4.5 microns. Drying temperature 82-88 degrees Celsius, dry coating thickness 2.2 microns.

[0104] Step 4: Formulation of the reinforcing layer coating Hydroxy acrylate resin 32 grams, maleic anhydride grafted polypropylene 6 grams, nano-alumina 3.5 grams, leveling agent 0.7 grams, mixed solvent of ethyl acetate and butyl acetate 48.8 grams. Isocyanate curing agent 9 grams was added before use.

[0105] Step 5: Patterned coating of the reinforcing layer Print a complex pattern of curves and grid elements, with a repeating unit of 50 mm by 50 mm. The depth of the cells is 25 microns, with a density of 75 lines per centimeter. The printing speed is 75 meters per minute. The drying temperature is 78 degrees Celsius, and the dry film thickness is 4.5 microns.

[0106] Step 6: First stage pre-corona Electrode spacing 2.0 mm, corona power 1.25 kW, processing speed 75 meters per minute. Corona value in the pattern area is 49 dynes.

[0107] Step 7: Second stage differential corona 0.45 kW is applied to the pattern area, and 1.1 kW is applied to the background area. The pattern area is maintained at 49 dynes, and the background area reaches 28 dynes, with a difference of 21 dynes.

[0108] Step 8: Spray stabilizer Spray amount 0.6 grams per square meter, drying temperature 52 degrees Celsius, time 9 seconds.

[0109] Step 9: Post-processing Age for 24 hours. Apply pressure sensitive adhesive 22 grams per square meter. Print brown ink. Slit to 1000 mm width and thread to 10 mm width.

[0110] Performance test results: Corona value: 49 dynes on pattern area, 28 dynes on background, 21 dynes difference Pattern accuracy: curve edge smooth, grid line uniform, overprint error plus or minus 0.08 mm Anti-removal mark effect: after removal, the pattern on the pull line and the adherend forms a positive and negative contrast, with obvious visual effect Example 4: high corona difference unsealing pull line First step: substrate selection A 38-micron-thick biaxially stretched polypropylene film is selected.

[0111] Second step: preparation of shielding layer coating Take 45 grams of silicone resin, 8 grams of nano-silicon dioxide, 5 grams of zinc stearate, and 2 grams of coupling agent KH-550, and add 40 grams of solvent oil.

[0112] Third step: coating the shielding layer Anilox roll 220 lines per inch, coating speed 65 meters per minute, wet coating thickness 5 microns. Drying temperature 85-92 degrees Celsius, dry coating thickness 2.5 microns.

[0113] Fourth step: preparation of the reinforcing layer coating Take 35 grams of hydroxyl acrylate resin, 8 grams of maleic anhydride grafted polypropylene, 5 grams of nano-alumina, and 1 gram of leveling agent, and add 39 grams of mixed solvent. Add 12 grams of curing agent before use.

[0114] Fifth step: patterned coating of the reinforcing layer Print a barcode pattern, 0.3-1.0 mm wide. Net depth 18 microns, density 80 lines per centimeter. Dry film thickness 3 microns.

[0115] Sixth step: first stage pre-corona Corona power 1.5 kW, electrode spacing 1.5 mm, processing speed 65 m / min. Corona value of barcode area 52 dynes.

[0116] Seventh step: second stage differential corona Apply 0.3 kW to the barcode area and 1.2 kW to the background area. The barcode area maintains 52 dynes, the background area reaches 25 dynes, and the difference is 27 dynes. This is the largest corona difference among all examples.

[0117] Eighth step: spray stabilizer Spray amount 0.8 grams per square meter, drying temperature 60 degrees Celsius, time 12 seconds.

[0118] Ninth Step: Post Processing Aged for 48 hours. Coated with pressure sensitive adhesive at 30 grams per square meter. Printed with black ink. Slit into 8mm wide pull tabs.

[0119] Performance Test Results: Corona Value: 52 dynes on barcode area, 25 dynes on background, 27 dynes difference Ink Adhesion: Greater than 12 N / 25mm on barcode area, 1.5-2 N / 25mm on background area Anti-tamper residue effect: Maximum difference due to corona, high contrast after opening, barcode remains intact on pull tab, background completely transferred Barcode readability: Barcode can still be identified by a barcode scanner after opening, 98% identification rate Example 5: Low cost anti-tamper pull tab First Step: Substrate Selection A 25 micron biaxially oriented polypropylene film was selected. This is the thinnest substrate and lowest cost of all the examples.

[0120] Second Step: Formulation of Shielding Layer Coating Take 35 grams of silicone resin, 5 grams of nano-silica, 3 grams of zinc stearate, and 1 gram of coupling agent KH-550, and add 56 grams of solvent oil. The amount of silicone resin and nano-silica in this formulation is at the lower end of the range, reducing cost.

[0121] Third Step: Coating of Shielding Layer Anilox roll 180 lines per inch, coating speed 80 meters per minute, wet coating thickness 3 microns. Drying temperature 80 degrees Celsius, dry coating thickness 1.5 microns. The thin coating reduces material cost.

[0122] Fourth Step: Formulation of Reinforcing Layer Coating Take 25 grams of hydroxyl acrylic resin, 5 grams of maleic anhydride grafted polypropylene, 3 grams of nano-alumina, and 0.5 grams of leveling agent, and add 58.5 grams of mixed solvent. Add 8 grams of curing agent before use.

[0123] Fifth Step: Patterned Coating of Reinforcing Layer Print a simple line and number combination pattern. Anilox depth 18 microns, density 60 lines per centimeter. Dry film thickness 3 microns.

[0124] Sixth Step: First Stage Pre-corona Corona power 1.2 kilowatts, electrode spacing 2.0 millimeters, processing speed 80 meters per minute. Corona value on pattern area 48 dynes.

[0125] Seventh Step: Second Stage Differential Corona Pattern area applied 0.5 kW, background area applied 0.8 kW. Pattern area maintained 48 dynes, background area reached 28 dynes, difference 20 dynes. Although the difference value is at the lower end of the range, the anti-tamper requirements are still met.

[0126] Eighth step: spray stabilizer Spray amount 0.5 grams per square meter, which is the minimum spray amount. Drying temperature 50 degrees Celsius, time 8 seconds.

[0127] Ninth step: post-processing Aged for 24 hours. Coated with pressure sensitive adhesive 20 grams per square meter. Printed with single color ink. Cut into 12 millimeter width pull tabs.

[0128] Performance test results: Corona value: pattern area 48 dynes, background 28 dynes, difference 20 dynes Cost analysis: compared to example 1, the material cost is reduced by about 25%, mainly by thinning the substrate and reducing the coating thickness Anti-tamper trace effect: although the corona difference is at the minimum value, a clear pattern can still be formed after being peeled off, meeting the basic anti-tamper requirements Applicable scenarios: suitable for applications where anti-tamper requirements are not high but cost control is needed Comparative example Comparative example 1: prior art single layer coating scheme First step: substrate preparation A 38 micrometer thick biaxially stretched polypropylene film is selected.

[0129] Second step: preparation of anti-tamper coating According to the prior art formula: epoxy resin 25 grams, dispersing agent 3 grams, wetting agent 1 gram, 120 gasoline 71 grams, mix and stir.

[0130] Third step: patterned coating The anti-tamper coating is coated using screen printing to form a two-dimensional code pattern. After coating, dry the coating, the coating thickness is about 5 microns to 8 microns.

[0131] Fourth step: corona treatment The entire surface is treated with a single power corona. Corona power 1.0 kW, treatment speed 70 meters per minute.

[0132] Fifth step: test corona value The coating part measured a corona value of 30 dynes, and the uncoated part measured a corona value of 40 dynes, with a corona value difference of only 10 dynes.

[0133] Sixth step: post-processing Coated with pressure sensitive adhesive 25 grams per square meter. Printed with black ink. Cut into 12 millimeter width pull tabs.

[0134] Performance test results: Corona value difference: only 10 dynes, far lower than the 20 dynes to 27 dynes of the present application Ink adhesion difference: 6 N / mm in the coated area and 4 N / mm in the uncoated area, with a small difference Anti-removing trace effect: low pattern contrast after removal, blurred boundary, and incomplete ink transfer in some areas Two-dimensional code recognition rate: only 78%, far lower than 97% in Example 1 Corona stability: the corona value in the coated area decays to 26 dynes after 6 months, with a decay rate of 13.3%, poor stability Comparison with the present application: The prior art scheme used in this comparative example has a small corona value difference and unsatisfactory anti-counterfeiting effect. The main defects include: 1. Single-layer coating cannot achieve precise corona control, and the corona shielding effect of the coating area is limited; 2. Lack of corona stabilization treatment, with fast corona value decay; 3. The difference in ink adhesion is not obvious, resulting in low pattern contrast and unclear boundary; 4. Low recognition rate of anti-counterfeiting patterns, with limited practical value.

[0135] Comparative Example 2: No corona stabilizer scheme The double-layer coating system and gradient corona treatment of the present application are used, but the corona stabilizer spraying step is omitted.

[0136] First to seventh steps: The first to seventh steps of Example 1 are followed, including coating a double-layer coating and two-stage corona treatment.

[0137] Eighth step: omit stabilizer spraying Skip the stabilizer spraying step and directly wind and age.

[0138] Ninth to thirteenth steps: Complete the subsequent steps according to Example 1.

[0139] Performance test results: Initial corona value: 50 dynes in the two-dimensional code area and 26 dynes in the background area, with a difference of 24 dynes, the same as Example 1 Corona stability test: After 1 month of storage: 46 dynes in the two-dimensional code area and 25 dynes in the background area, with a decay rate of 8% After 3 months of storage: 42 dynes in the two-dimensional code area and 24 dynes in the background area, with a decay rate of 16% ​After 6 months of storage: 38 dynes in the QR code area, 23 dynes in the background area, decay rate 24% Anti-tamper trace effect change: Fresh sample: clear pattern, high contrast After 3 months of storage: pattern contrast decreased, partial area ink transfer incomplete After 6 months of storage: pattern blurred, border unclear, anti-counterfeiting effect decreased significantly QR code recognition rate: decreased to 82% after 6 months of storage Comparison with the present invention: Although this comparative example uses a double-layer coating and gradient corona treatment, it lacks a corona stabilizer, resulting in a significant decay in corona value over time. The corona value decay rate after 6 months is as high as 24%, which is 6 times that of Example 1. This shows that the corona stabilizer is crucial for locking surface polar groups and maintaining corona value stability. Without the stabilizing treatment, the anti-counterfeiting effect will quickly deteriorate over time, the shelf life will be significantly shortened, and the practical value will be reduced.

[0140] Comparative Example 3: Single-stage corona treatment scheme Use the double-layer coating system and corona stabilizer of the present invention, but only perform a single corona treatment, not a two-stage gradient corona.

[0141] First to fifth steps: Prepare the substrate, apply the double-layer coating according to Example 1.

[0142] Sixth step: single-stage corona treatment Perform a single corona treatment on the entire web without distinguishing between the enhancement layer and the shielding layer areas. The corona power is set to a medium value of 0.8 kilowatts, the electrode spacing is 1.8 millimeters, and the treatment speed is 70 meters per minute.

[0143] Seventh step: spray stabilizer Spray the stabilizer according to the method of Example 1.

[0144] Eighth to thirteenth steps: Complete the subsequent processing according to Example 1.

[0145] Performance test results: Corona value test: The corona value in the QR code area reaches 42 dynes due to the help of the enhancement layer coating The corona value in the background area is 32 dynes due to the inhibition of the shielding layer The difference in corona value is only 10 dynes, which is much lower than the 24 dynes of Example 1 Ink adhesion: 7 Newtons per 25 millimeters in the QR code area, 5 Newtons per 25 millimeters in the background area, with a small difference Anti-peeling and trace effect: after peeling, the pattern contrast is low, the boundary is not clear enough, and uneven ink distribution occurs in some areas Two-dimensional code recognition rate: 83%, significantly lower than 97% of Example 1 Comparison with the present application: This comparative example illustrates the importance of two-stage gradient corona treatment. The first stage of pre-corona applies high-power treatment to the enhancement layer area, achieving an extremely high corona value for this area; the second stage of differential corona applies different powers to different areas, maintaining a high corona value for the enhancement layer and moderately treating the shielding layer. The synergistic effect of the two-stage treatment can achieve a large corona difference of more than 20 dynes.

[0146] Single-stage treatment cannot meet the different needs of the two areas. If the power is too high, the corona value of the shielding layer area will also increase; if the power is too low, the corona value of the enhancement layer area will not be enough. Therefore, only a moderate difference value can be achieved, and the anti-counterfeiting effect is not ideal.

[0147] Comparative Example 4: No nano-materials scheme Use the double-layer coating structure and the entire process flow of the present application, but remove the nano-silicon dioxide and nano-aluminum oxide from the coating formula.

[0148] Shielding layer formula adjustment: Silicone resin 46 grams, zinc stearate 4 grams, coupling agent KH-550 1.5 grams, solvent oil 48.5 grams. Remove 6.5 grams of nano-silicon dioxide.

[0149] Enhancement layer formula adjustment: Hydroxy acrylate resin 34 grams, maleic anhydride grafted polypropylene 6.5 grams, leveling agent 0.8 grams, isocyanate curing agent 10 grams, mixed solvent 48.7 grams. Remove 4 grams of nano-aluminum oxide.

[0150] Other steps: Follow Example 1 exactly.

[0151] Performance test results: Corona value test: Two-dimensional code area 45 dynes, lower than 50 dynes of Example 1 Background area 29 dynes, higher than 26 dynes of Example 1 Corona value difference 16 dynes, lower than 24 dynes of Example 1 Surface roughness: Enhancement layer area Ra value about 80 nanometers, much lower than 150 to 250 nanometers of Example 1 Shielding layer area Ra value about 30 nanometers, lower than 50 to 100 nanometers of Example 1 Ink mechanical anchoring force: due to low surface roughness, ink mechanical embedding effect is weak, and adhesion mainly relies on chemical bonding Anti-removing trace effect: pattern contrast is lower than example 1, and boundary definition decreases Wear resistance: after 10 times of reciprocating friction, the enhanced layer area appears slight wear, and the ink adhesion decreases by about 15% Comparison with the present application: This comparative example illustrates the important role of nanomaterials in the present application. Nano-silica forms low-energy surfaces and micro-rough structures in the shielding layer, enhancing the corona shielding effect; nano-alumina provides active sites and nano-protrusions in the enhanced layer, improving corona sensitivity and ink anchoring force.

[0152] After removing the nanomaterials, although a certain corona difference can still be formed, the difference value is significantly reduced, the micro-nano structure disappears, leading to a decrease in anti-counterfeiting effect and poor wear resistance. This proves that micro-nano structure regulation is an indispensable part of the technical solution of the present application.

[0153] Comparative example 5: reverse coating scheme Reverse the coating sequence of the present application, first coat the enhanced layer, then coat the shielding layer.

[0154] First step to second step: Prepare the substrate according to example 1.

[0155] Third step: full-width enhanced layer coating Coat the enhanced layer formula in example 1 full-width, without patterning. After coating, dry, thickness 4 microns.

[0156] Fourth step: patterned shielding layer coating Coat the shielding layer formula in example 1 on the enhanced layer using intaglio printing to form a two-dimensional code pattern. After coating, dry, thickness 2 microns.

[0157] Fifth step to seventh step: Two-stage gradient corona treatment according to example 1.

[0158] Eighth step to thirteenth step: Complete subsequent processing according to example 1.

[0159] Performance test results: Corona value test: The two-dimensional code area has a shielding layer as the surface layer, and the corona value is only 35 dyne Although the background area has an enhanced layer as the bottom layer, the corona treatment mainly acts on the surface layer, and the corona value is 38 dyne The corona value difference is only 3 dyne, almost no difference; Anti-removing and trace-remaining effect: due to the small difference in corona value, the pattern contrast is hardly visible after being removed, and the anti-counterfeiting function is completely ineffective. Coating adhesion: the shielding layer is coated on the reinforcing layer, and the adhesion between the two layers is poor, and delamination occurs in some areas.

[0160] Comparison with the present application: This comparative example illustrates the criticality of coating sequence. In the present application, the shielding layer is used as the bottom layer and the reinforcing layer as the top layer. In this way, the different coatings on the surface layer are directly affected by the corona treatment, thereby forming a significant corona difference.

[0161] If the sequence is reversed, the corona treatment can only act on the outermost shielding layer, and the bottom reinforcing layer cannot function, resulting in the inability to form a corona difference. In addition, the low surface energy characteristics of the shielding layer also make it difficult to adhere well with the reinforcing layer, resulting in coating delamination problems.

[0162] This proves that the technical solution of "first coating the shielding layer, then patterning the reinforcing layer" in the present application is irreplaceable, and the coating sequence cannot be reversed.

[0163] Through the comparative analysis of the above examples and comparative examples, the technical advantages of the present application are as follows: The corona value difference of the embodiment of the present application reaches 20 to 27 dynes, which is 2 to 2.7 times of 10 dynes of the prior art comparative example 1. This large corona difference ensures the significant difference in ink adhesion, thereby realizing the high-contrast anti-removing and trace-remaining effect.

[0164] The combination of the bottom shielding layer and the top reinforcing layer realizes the precise control of the corona performance of different areas. Comparative example 5 proves that the coating sequence cannot be reversed, and comparative example 4 proves that the nano material is indispensable. The double-layer coating system is the core to achieve the technical effect.

[0165] Comparative example 3 shows that single-stage corona treatment cannot achieve a large corona difference. The two-stage gradient corona treatment of the present application makes the reinforcing layer reach an extremely high corona value in the first stage, and maintains a high value and makes the shielding layer reach a moderate corona value in the second stage. The two stages work together to achieve the optimal effect.

[0166] Comparative example 2 proves the key role of the corona stabilizer. The corona value of the embodiment of the present application has a decay rate of less than 5% in 6 months, while the comparative example 2 without stabilizer has a decay rate of up to 24%. The stability is improved by nearly 5 times, greatly extending the product shelf life and anti-counterfeiting validity period.

[0167] The present application not only realizes visual anti-counterfeiting, but also realizes tactile anti-counterfeiting and microscopic anti-counterfeiting through micro-nano structure regulation, realizes instrument detection anti-counterfeiting through precise corona value control, forms a multiple anti-counterfeiting system, and the anti-counterfeiting level is significantly higher than that of the prior art.

[0168] All examples adopt mature coating, printing and corona treatment equipment, process parameters are specific and good repeatability. Example 5 proves that the technology can realize cost control through parameter optimization, and is suitable for large-scale production.

[0169] In summary, the present application solves the problems of small difference, poor anti-counterfeiting effect and low stability in the prior art by the organic combination of material innovation, structure innovation and process innovation, realizes the technical effects of high contrast, high stability and multiple anti-counterfeiting, and has significant technical progress and application value.

[0170] The present application encompasses any substitution, modification, equivalent method and scheme made on the essence and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be fully understood without the description of these details for those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits are not described in detail.

[0171] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be regarded as the protection scope of the present application.

Claims

1. A corona differential treatment tamper-evident, tamper-proof, and reclosure pull, characterized in that, From bottom to top, sequentially comprising: a base film layer, which is a biaxially oriented polypropylene film or a polyethylene terephthalate film with a thickness of 25-50 microns; a corona shielding layer, which is coated on the upper surface of the base film layer, and the formula of the corona shielding layer comprises, by weight percentage, 35-45% of silicone resin, 5-8% of nano-silicon dioxide with a particle size of 20-50 nanometers, 3-5% of zinc stearate, 1-2% of coupling agent KH-550, and the balance of No. 120 solvent oil; the dry coating thickness of the corona shielding layer is 1.5-2.5 microns; a selective corona enhancement layer, which is coated on the preset anti-fake pattern area of the surface of the corona shielding layer in a patterned manner, and the formula of the selective corona enhancement layer comprises, by weight percentage, 25-35% of hydroxyl acrylic resin, 8-12% of isocyanate curing agent, 5-8% of maleic anhydride grafted polypropylene, 3-5% of nano-aluminum oxide with a particle size of 30-60 nanometers, 0.5-1% of leveling agent, and the balance of mixed solvent of ethyl acetate and butyl acetate with a mass ratio of 3:1; the dry coating thickness of the selective corona enhancement layer is 3-5 microns; an adhesive layer, which is coated on the surface of the selective corona enhancement layer and the corona shielding layer; a printing ink layer, which is coated on the surface of the adhesive layer; the corona value of the area covered by the selective corona enhancement layer is 48-52 dynes, the corona value of the area covered by the corona shielding layer is 25-28 dynes, and the difference between the corona values of the two areas is 20-27 dynes.

2. The corona differentiated treatment tamper-evident, tamper-proof, and evidence- leaving, tear-open, pull-ring of claim 1 wherein, The hydroxyl value of the hydroxyl acrylic resin is 80-120 mg KOH / g; the grafting rate of the maleic anhydride grafted polypropylene is 0.5-1.2%.

3. The corona differentiated treatment tamper-evident, tamper-proof, and evidence- leaving, tear-open, pull-wire of claim 1 wherein, The surface roughness Ra value of the area covered by the selective corona enhancement layer is 150-250 nanometers; the surface roughness Ra value of the area covered by the corona shielding layer is 50-100 nanometers.

4. The corona differentiated treatment tamper-evident, tamper-proof, and evidence- leaving, tear-open, pull-wire of claim 1 wherein, The preset anti-fake pattern is one or a combination of two or more of a two-dimensional code, a bar code, a word, a company logo, and a pattern.

5. A method of making a tamper-evident, process-differentiated, opening- revealing, tear-open pull strip according to any one of claims 1 to 4, characterized in that The method comprises the following steps: Step 1: the biaxially oriented polypropylene film or the polyethylene terephthalate film is used as the base film layer, and the surface dust and static electricity are removed through a dust removal roller and an electrostatic elimination device; Step 2: the corona shielding layer coating is applied on the upper surface of the base film layer in full width, and the formula of the corona shielding layer coating comprises, by weight percentage, 35-45% of silicone resin, 5-8% of nano-silicon dioxide with a particle size of 20-50 nanometers, 3-5% of zinc stearate, 1-2% of coupling agent KH-550, and the balance of No. 120 solvent oil; a screen roller coating method is adopted, the line number of the screen roller is 180-220 lines per inch, and the wet coating thickness is 3-5 microns; after coating, drying is performed at 80-90 degrees Celsius for 15-20 seconds to obtain the corona shielding layer with a dry coating thickness of 1.5-2.5 microns; Step three, patterned coating of a selective corona enhancement layer coating on the surface of the corona shielding layer, the selective corona enhancement layer coating has a formulation consisting of, by weight percentage: 25% to 35% of hydroxyl acrylic resin, 8% to 12% of isocyanate curing agent, 5% to 8% of maleic anhydride grafted polypropylene, 3% to 5% of nano alumina with a particle size of 30 nanometers to 60 nanometers, 0.5% to 1% of leveling agent, and the rest of mixed solvent of ethyl acetate and butyl acetate with a mass ratio of 3 to 1; the coating is applied by laser engraved micro-hole roller gravure printing method in the preset anti-fake pattern area, the cell depth is 18 microns to 25 microns, the cell density is 60 lines per centimeter to 80 lines per centimeter, and the wet coating thickness is 6 microns to 10 microns; After coating, drying at 70 degrees Celsius to 80 degrees Celsius for 10 seconds to 15 seconds to obtain a dry coating thickness of 3 microns to 5 microns of the selective corona enhancement layer; Step four, first stage pre-corona treatment is performed on the area coated with the selective corona enhancement layer, the corona power is 1.2 kilowatts to 1.5 kilowatts, the processing speed is 60 meters per minute to 80 meters per minute, and the electrode spacing is 1.5 millimeters to 2.0 millimeters, so that the corona value of the selective corona enhancement layer covered area reaches 48 dynes to 52 dynes; Step five, second stage differential corona treatment is performed on the entire web, 0.3 kilowatts to 0.5 kilowatts of corona power is applied to the selective corona enhancement layer covered area, 0.8 kilowatts to 1.2 kilowatts of corona power is applied to the corona shielding layer covered area, the electrode spacing is 1.5 millimeters to 2.0 millimeters, and the processing speed is 60 meters per minute to 80 meters per minute, so that the selective corona enhancement layer covered area maintains a corona value of 48 dynes to 52 dynes, and the corona value of the corona shielding layer covered area reaches 25 dynes to 28 dynes; Step six, within 3 seconds to 5 seconds after completing step five, spray a corona stabilizer, the corona stabilizer has a formulation consisting of, by weight percentage: 5% of polyvinyl alcohol, 2% of sodium chloride, and 93% of deionized water; the spraying amount is 0.5 grams per square meter to 0.8 grams per square meter; after spraying, drying at 50 degrees Celsius to 60 degrees Celsius for 8 seconds to 12 seconds; Step seven, after winding, aging in an environment with a temperature of 23 degrees Celsius plus or minus 2 degrees Celsius and a relative humidity of 50% plus or minus 5% for 24 hours to 48 hours; Step eight, coating an adhesive layer on the surface treated by corona; Step nine, printing an ink layer on the surface of the adhesive layer; Step ten, after slitting, cutting into a tear-off pull line with a width of 5 millimeters to 25 millimeters.

6. The production method according to claim 5, characterized by, The roller material of the laser engraved micro-hole roller gravure in step three is copper-based chromium plated material, and the cell shape is inverted conical.

7. The preparation method according to claim 5, characterized in that, The polyvinyl alcohol in step six has a degree of polymerization of 1700 to 2000; the corona stabilizer is sprayed through an ultrasonic atomizing nozzle with an atomized particle size of 10 microns to 30 microns.

8. The preparation method according to claim 5, characterized in that, In step four, a segmented electrode control system is used to perform selective corona treatment on the selective corona enhancement layer covered area, and precise positioning is achieved through a tension sensor and a pattern recognition system.

9. The preparation method according to claim 5, characterized in that, The power partition control module is used in step five to apply different corona power to different areas, and the power partition control module controls the corona power of each area according to the pattern positioning information in step four.

Images