Method and device for processing anti-fake kraft liner board

Abstract

The invention provides an anti-fake kraft box paperboard processing method and device, and relates to the technical field of paper production, and the method comprises the following steps: base material pretreatment: conveying a base material paperboard to a pretreatment mechanism for water-based cleaning; double-layer coating: coating temperature change ink coating liquid on an upper coating roller of a double-layer coating mechanism; the lower coating roller is coated with microcapsule color developing agent coating liquid; the base material layer and the anti-fake coating are compounded through a compounding mechanism, and then the base material is pressed through an embossing and drying integrated roller of an embossing and drying mechanism; performing multi-layer curing; and anti-counterfeiting embedding. Comprising a pretreatment mechanism, a double-layer coating mechanism, a compounding mechanism, an embossing drying mechanism, an ultraviolet curing mechanism and a digital watermarking mechanism. Compared with a single technology, the anti-counterfeiting identification rate is remarkably improved, the anti-counterfeiting level and reliability are remarkably enhanced, the color development intensity attenuation is small after multiple times of friction, and the compression strength is high. The device realizes recovery of redundant coating liquid and cleaning and maintenance of a coating environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paper production, more particularly, the present application relates to a kind of anti-fake kraft linerboard processing method and device. BACKGROUND

[0002] Under the dual driving of packaging industry technology iteration and anti-fake demand upgrading, as a high-end packaging material, the technical development path of anti-fake kraft linerboard presents a multi-dimensional innovation trend. Currently, the anti-fake security packaging market continues to expand at an average annual compound growth rate of 5.4%, and it is expected that the global market size will exceed 4 billion US dollars in 2025. This growth is a direct reflection of the diversification of retail channels and the intensification of counterfeit and inferior problems.

[0003] The prior art realizes the integration of the anti-fake function through a multi-layer coating process. The temperature change ink layer becomes transparent when detected by high temperature, making the information of the bottom anti-fake coating layer appear, and the photochromic ink layer enhances the anti-fake level through different color combinations. Although this technology realizes the preliminary combination of physical-chemical anti-fake, it does not involve the integration of digital watermarking technology, and the anti-fake response speed and durability still have room for improvement.

[0004] The application of temperature change ink in the anti-fake field is relatively mature. Studies have shown that temperature change anti-fake ink using bromocresol purple as a color change agent and acetic acid microcapsules as a carrier can achieve reversible or irreversible color change through temperature change. Acetic acid microcapsules usually have a double-layer wall material structure, with polyurethane acrylic acid and other oil-phase materials in the inner layer to provide mechanical strength, and acetic acid salt water-phase materials in the outer layer to enhance compatibility with water-based systems. However, in existing technologies, microcapsule color developers are often used independently and do not form a response system with temperature change ink, and the pressure resistance and color development stability of microcapsules still need to be optimized.

[0005] Double-layer coating technology has been widely used in lithium battery negative electrode materials, optical functional films, and other fields. This technology realizes precise coating of two layers of coating liquid through a die coordination control system and uses interfacial control technology to improve coating adhesion. In the field of packaging materials, some coating equipment uses a doctor blade system to control coating thickness, such as an arc-shaped doctor blade plate that adjusts the gap with the coating roller to control the coating amount. However, existing double-layer coating mechanisms lack specific designs for the sealing of ventilation channels, the recovery of excess coating liquid, and the cleaning and maintenance of the coating environment, which limits coating efficiency and material utilization.

[0006] To improve the physical properties of paperboard, the prior art realizes the improvement of edge compression strength and burst resistance through material modification and process optimization. For example, the honeycomb core structure is used to enhance the anti-extrusion performance, or the water absorption is reduced by the action of hydrophobic chain segments (such as polycarbonate diol) and water-resistant monomers (such as methyl methacrylate). However, such technologies do not combine the physical property improvement with the durability of the anti-fake coating, resulting in the easy failure of the anti-fake mark under the working conditions such as friction and extrusion.

[0007] In summary, although the prior art has made progress in the fields of anti-fake coating, coating process, material synthesis, etc., it has not realized the integration of the triple anti-fake technology of temperature change ink-microcapsule color developer-digital watermark, and there are deficiencies in coating durability, production efficiency and physical properties. SUMMARY

[0008] In order to overcome the above-mentioned defects of the prior art, the present application provides a method for processing anti-fake kraft box paperboard and a device thereof, aiming to solve the problem of single anti-fake measure and the deficiencies in coating durability, production efficiency and physical properties.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for processing anti-fake kraft box paperboard, comprising the following steps,

[0010] (1) substrate pretreatment: the substrate paperboard is conveyed to the pretreatment mechanism, the spray head performs water-based cleaning at a pressure of 1.2-1.8 MPa, the cleaning liquid temperature is 45-55℃, and the spraying time is 15-20s;

[0011] (2) double-layer coating: the upper coating roller of the double-layer coating mechanism coats the temperature change ink coating liquid, the color developing temperature is 60-80℃, and the coating amount is 8-12g / m 2 ; the lower coating roller coats the microcapsule color developer coating liquid, the particle size is 10-20μm, and the coating thickness is 15-25μm;

[0012] (3) composite embossing: after the substrate layer and the anti-fake coating are compounded by the composite mechanism, the substrate is pressed and dried by the embossing and drying integrated roller of the embossing and drying mechanism, the roller pressure is 0.8-1.2MPa, the embossing depth is 0.3-0.5mm, the infrared heating temperature is 150-180℃, and the drying time is 30-45s;

[0013] (4) multi-layer curing: the ultraviolet lamp group of the ultraviolet curing mechanism emits 365nm ultraviolet light, the photoinitiator nozzle (502) synchronously sprays 0.1% concentration initiator, the spraying amount is 0.05-0.1mL / cm 2 , and the curing time is 10-15s;

[0014] (5) anti-fake embedding: the digital watermark mechanism sprays 12-bit binary code on the edge of the paperboard, the inkjet amount is 0.5-1.0g / m 2Encoding resolution 600 dpi, inkjet height 3-5 mm.

[0015] In a preferred embodiment, the temperature-variable ink coating solution comprises the following components by mass percentage:

[0016] Acetic acid microcapsules 25-35%

[0017] Water-based PUA emulsion 40-50%

[0018] Bromocresol purple-phtalic acid complex system 15-25%

[0019] Dispersant 1-3%

[0020] Defoamer 0.5-1%

[0021] The molar ratio of bromocresol purple to phtalic acid is 1:1.2-1.8.

[0022] In a preferred embodiment, the acetic acid microcapsules comprise a core material, an inner layer, and an outer layer,

[0023] The core material is acetic acid.

[0024] The inner layer is a polyurethane acrylic acid and ethylene glycol diacrylate complex oil phase wall material.

[0025] The outer layer is an acetic acid salt water phase wall material.

[0026] In a preferred embodiment, the water-based PUA emulsion comprises the following components by weight:

[0027]

[0028] In a preferred embodiment, the method for preparing the water-based PUA emulsion comprises the following steps:

[0029] Step 1: Prepolymer synthesis

[0030] Raw material preparation: under the protection of dry nitrogen, add polycarbonate diol to the reaction kettle, heat to 110-120°C, vacuum dehydrate for 1.5-2 hours, and ensure that the water content is ≤0.05%;

[0031] Isocyanate reaction: cool to 70-75°C, add isophorone diisocyanate (IPDI), and drop 0.05 parts by weight of catalyst (dibutyltin dilaurate). Stir for 2.5-3 hours until the NCO content reaches the theoretical value (titrated by di-n-butylamine method);

[0032] Step 2: Hydrophilic chain extension and neutralization

[0033] Chain extension reaction: cooling to 50-55℃, adding 2,2-dimethylol propionic acid (DMPA), slowly warming to 75-80℃, continuing to react for 1.5-2 hours until the isocyanate group (NCO) is completely converted;

[0034] Neutralization and salting: cooling to 40-45℃, adding triethylamine (TEA), stirring for 20-30 minutes until the carboxylic acid group is completely neutralized (pH≈7.5-8.5) to form an ionic polyurethane prepolymer;

[0035] Step 3: Acrylate monomer mixing and pre-emulsification

[0036] Monomer mixing: in another container, mix methyl methacrylate (MMA), butyl acrylate (BA), and azobisisobutyronitrile (AIBN) uniformly to make a monomer premix solution;

[0037] Pre-emulsification: slowly add the monomer premix solution to the polyurethane prepolymer, high-speed stirring (800-1000 rpm) for 15-20 minutes to form a stable pre-emulsion;

[0038] Step 4: Free radical polymerization and dispersion

[0039] Polymerization reaction: transfer the pre-emulsion to a polymerization kettle, warm to 75-80℃, and incubate for 3-4 hours until the monomer conversion rate is ≥98%;

[0040] Water dispersion: cool to 30-35℃, slowly add deionized water under high-speed stirring, continue to stir for 30-40 minutes to form a translucent aqueous emulsion;

[0041] Step 5: Post-treatment

[0042] Filtration: filter the emulsion through 180-220 mesh filter cloth to remove possible gel particles.

[0043] A method and device for processing anti-counterfeit kraft paperboard: including a pretreatment module mechanism, a double-layer coating mechanism, a composite mechanism, a embossing and drying mechanism, a UV curing mechanism and a digital watermark mechanism, the pretreatment mechanism, double-layer coating mechanism, composite mechanism, embossing and drying mechanism, UV curing mechanism and digital watermark mechanism are sequentially arranged.

[0044] The preferred technical solution, the double-layer coating mechanism includes an upper coating roller and a lower coating roller, the upper coating roller is located above the lower coating roller, and the two ends of the upper coating roller and the lower coating roller are rotatably connected to the end plate, and a rotation groove is provided between the end plates and respectively located behind the upper coating roller and the lower coating roller, and an arc-shaped scraper is rotatably provided between the rotation grooves, and the outer side of one side of the arc-shaped scraper plate behind the upper coating roller is tangent to the outer roller surface of the upper coating roller, and the outer side of one side of the arc-shaped scraper plate behind the lower coating roller is tangent to the outer roller surface of the lower coating roller. When coating, the upper coating roller and the lower coating roller respectively form a ventilation channel between the arc-shaped scraper plate behind them and the substrate paperboard, and a pulse air jet head is provided on the end plate and at one end side of the ventilation channel, the outer end of the pulse air jet head extends to the outside of the end plate, and a discharge port is provided on the end plate and at the other end side of the ventilation channel.

[0045] The preferred technical solution is that the outer sides of the ends of the arc-shaped scraper plates are fixed with adjusting screws, the positions of the end plates corresponding to the adjusting screws are provided with arc-shaped grooves, the adjusting screws are slidingly provided inside the arc-shaped grooves, and the outer sides of the adjusting screws are provided with fastening nuts.

[0046] According to a preferred technical solution, a sealing strip is provided at the location where the arc-shaped scraper plate is tangent to the upper coating roller and the lower coating roller.

[0047] This invention achieves a triple layer of physical, chemical, and digital security by combining three anti-counterfeiting technologies: temperature-dependent ink, microcapsule developer, and digital watermark. Parameters in each step are optimized to ensure the bond strength and durability between the anti-counterfeiting layer and the substrate. After 50 friction cycles, the digital watermark maintains a readability of level 5 (600 dpi), and the color intensity of the temperature-dependent ink decreases by less than 10%. The integrated design of the composite embossing and curing steps shortens the overall production cycle and improves production efficiency compared to traditional processes.

[0048] The pH color change property of bromocresol purple of the present invention cooperates with the crystallization-melting transition of terephthalic acid to broaden the temperature response range. The inner oil phase wall material (polyurethane acrylic) of the acetic acid microcapsule structure provides mechanical strength, while the outer water phase wall material (acetate) enhances compatibility with aqueous systems.

[0049] The polyurethane chain segment with excellent comprehensive performance is formed by the introduction of polycarbonate diol (PCD) in the water-based PUA emulsion of the application, the combination of polycarbonate diol (PCD) and isophorone diisocyanate (IPDI). Polycarbonate diol (PCD) as the soft segment provides excellent hydrolysis resistance and mechanical properties, while isophorone diisocyanate (IPDI) as the hard segment enhances the chemical resistance and mechanical strength of the emulsion. Isophorone diisocyanate (IPDI) is an alicyclic diisocyanate with moderate reactivity and unique chemical structure. When polycarbonate diol (PCD) reacts with isophorone diisocyanate (IPDI), the generated polyurethane chain segment combines the structural characteristics of alicyclic and polycarbonate. In this combination, isophorone diisocyanate (IPDI) as the hard segment not only provides good mechanical properties and chemical resistance for polyurethane, but also enhances the weather resistance of polyurethane through its alicyclic structure; while isophorone diisocyanate (IPDI) as the soft segment, it gives polyurethane excellent hydrolysis resistance and flexibility. Compared with traditional methods, the combination of PCD and IPDI achieves a better balance in performance, with sufficient hardness and mechanical strength, as well as good flexibility and weather resistance. The alicyclic structure (non-aromatic isocyanate) of IPDI can significantly inhibit the photoyellowing effect of the polyurethane chain segment. During UV curing and long-term outdoor use, its unique cyclic structure can effectively block the formation of conjugated double bond systems, making the color difference ΔE of the anti-counterfeiting coating ≤1.2 after 500 hours of xenon lamp aging test, which is much better than the traditional aromatic isocyanate system (ΔE≥3.5). This property is crucial for maintaining the color stability of temperature change ink and the recognition accuracy of digital watermark, ensuring that the anti-counterfeiting features remain clear and identifiable during long-term storage and use.

[0050] 2,2-dimethylol propionic acid (DMPA) not only increases the molecular weight of polyurethane as a chain extender, but also provides good self-emulsifying properties to polyurethane by introducing carboxylic acid groups, which is the key to water-based. The synergistic effect of methyl methacrylate (MMA) and butyl acrylate (BA), methyl methacrylate (MMA) as a hard monomer, provides hardness and weather resistance; butyl acrylate (BA) as a soft monomer, provides flexibility and adhesion. Through free radical polymerization, the two form an acrylate copolymer with excellent performance, which penetrates each other with the polyurethane chain segment, forming an interpenetrating network structure, which significantly improves the comprehensive performance of the emulsion. Azobisisobutyronitrile (AIBN) precisely initiates the free radical polymerization of acrylate monomers, ensuring the smooth progress of the polymerization reaction; triethylamine (TEA) precisely neutralizes the carboxylic acid groups, forming a stable water-based dispersion, improving the stability and appearance of the emulsion.

[0051] The technical effects and advantages of the application are as follows:

[0052] Triple anti-counterfeiting performance improvement

[0053] Through the superposition of temperature-changing ink (chemical anti-counterfeiting), microcapsule color developing agent (physical anti-counterfeiting) and digital watermark (digital anti-counterfeiting), a physical-chemical-digital integrated anti-counterfeiting system is constructed. The anti-counterfeiting identification rate is significantly improved compared to single technology, the digital watermark has high resolution, large information capacity, short temperature change response time, and strong microcapsule breaking resistance, which significantly enhances the anti-counterfeiting level and reliability.

[0054] Coating performance optimization

[0055] Temperature-changing ink: temperature change response is achieved through a specific composite system, and the color developing intensity decreases little after multiple rubbings.

[0056] Microcapsule structure: the inner wall material provides mechanical strength, and the outer wall material enhances the compatibility of the system, with high pressure resistance.

[0057] Water-based PUA emulsion: an interpenetrating network structure is formed through specific combination, which endows the coating with excellent hydrolysis resistance, color fastness to rubbing and anti-yellowing performance.

[0058] Production efficiency and process integration

[0059] Composite embossing-curing integration: the embossing drying and ultraviolet curing steps are integrated to improve production efficiency. Double-layer coating mechanism improvement: precise control of coating liquid and recovery of excess material are achieved through specific design, reducing waste.

[0060] Physical performance enhancement

[0061] The physical performance indicators such as edge pressure strength and breaking resistance are significantly improved, with high color fastness to rubbing, meeting the stringent physical performance requirements of high-end packaging.

[0062] The physical performance indicators such as edge pressure strength and breaking resistance are significantly improved, with high color fastness to rubbing, meeting the stringent physical performance requirements of high-end packaging.

[0063] Optimization of double-layer coating mechanism

[0064] Precise control of coating liquid, recovery of excess coating liquid and cleaning and maintenance of coating environment are achieved, thereby improving coating efficiency and quality and reducing material waste. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 The structure diagram of the present application;

[0066] Figure 2 The structure diagram of the double-layer coating mechanism of the present application;

[0067] Figure 3 The structure diagram of the double-layer coating mechanism of the present application after removing the upper coating roller and the lower coating roller;

[0068] Figure 4 Schematic diagram of the cross-sectional structure of the double-layer coating mechanism of the present invention;

[0069] Figure 5 This is a schematic diagram of the structure of the curved scraper blade of the present invention;

[0070] In the figure: 1. Pretreatment mechanism; 2. Double-layer coating mechanism; 3. Laminating mechanism; 4. Spring; 5. Embossing and drying mechanism; 6. Digital watermarking mechanism; 7. Cardboard; 201. Upper coating roller; 202. Lower coating roller; 203. End plate; 204. Rotating trough; 205. Arc-shaped scraper plate; 206. Ventilation channel; 207. Pulse air jet head; 208. Discharge port; 209. Adjusting screw; 210. Arc-shaped slide; 211. Fastening nut; 212. Sealing strip. DETAILED DESCRIPTION

[0071] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0072] like Figures 1 to 5 shown

[0073] Example 1

[0074] A method for processing anti-counterfeiting kraft linerboard comprises the following steps:

[0075] (1) Substrate pretreatment: The substrate paperboard 7 is transported to the pretreatment mechanism 1, and the spray head performs water-based cleaning at a pressure of 1.2 MPa, the cleaning liquid temperature is 45°C, and the spraying time is 15 seconds;

[0076] (2) Double-layer coating: The upper coating roller 201 of the double-layer coating mechanism 2 applies a temperature-variable ink coating liquid with a color development temperature of 60°C and a coating amount of 8 g / m 2 ; The lower coating roller 202 is coated with a microcapsule developer coating liquid, with a particle size of 10 μm and a coating thickness of 15 μm;

[0077] (3) Composite embossing: After the substrate layer and the anti-counterfeiting coating are laminated by the laminating mechanism 3, the substrate is pressed by the embossing and drying integrated rollers of the embossing and drying mechanism 4, with a roller pressure of 0.8 MPa, an embossing depth of 0.3 mm, an infrared heating temperature of 150°C, and a drying time of 30 s;

[0078] (4) Multi-layer curing: The UV lamp group of the UV curing mechanism 5 emits 365 nm UV light, and the photoinitiator nozzle 502 simultaneously sprays 0.1% concentration initiator with a spray volume of 0.05 mL / cm2 Curing time 10s;

[0079] (5) Anti-fake embedded: digital watermarking mechanism 6 sprays 12-bit binary code on the edge of paperboard 7, inkjet amount 0.5g / m 2 Coding resolution 600dpi, inkjet height 3mm.

[0080] Temperature changeable ink coating solution includes the following mass percentage components:

[0081] Acetic acid microcapsule 25%

[0082] Water-based PUA emulsion 40%

[0083] Bromocresol purple-p-terephthalic acid composite system 15%

[0084] Dispersant 1%

[0085] Defoamer 0.5%

[0086] The molar ratio of bromocresol purple to p-terephthalic acid is 1:1.2.

[0087] The acetic acid microcapsule includes core material, inner layer and outer layer,

[0088] The core material is acetic acid;

[0089] The inner layer is a polyurethane acrylic acid and ethylene glycol diacrylate composite oil phase wall material;

[0090] The outer layer is an acetic acid salt water phase wall material.

[0091] The water-based PUA emulsion includes the following weight components,

[0092]

[0093]

[0094] The preparation method of the water-based PUA emulsion includes the following steps

[0095] Step 1: Prepolymer synthesis

[0096] Raw material preparation: under the protection of dry nitrogen, polycarbonate diol is added to the reaction kettle, the temperature is raised to 110°C, and vacuum dehydration is carried out for 1.5 hours to ensure that the water content is ≤0.05%;

[0097] Isocyanate reaction: cool to 70°C, add isophorone diisocyanate, add 0.05 parts by weight of catalyst dropwise, and stir for 2.5 hours until the NCO content reaches the theoretical value;

[0098] Step 2: Hydrophilic chain extension and neutralization

[0099] Chain extension reaction: cooling to 50℃, adding 2,2-dimethylol propionic acid, slowly warming to 75℃, continuing to react for 1.5 hours until the isocyanate group is completely converted;

[0100] Neutralization and salting: cooling to 40℃, adding triethylamine, stirring for 20 minutes until the carboxylic acid group is completely neutralized, pH is 7.5, forming an ionized polyurethane prepolymer;

[0101] Step 3: Acrylate monomer mixing and pre-emulsification

[0102] Monomer mixing: in another container, mix methyl methacrylate, butyl acrylate, azobisisobutyronitrile uniformly to make a monomer premix;

[0103] Pre-emulsification: slowly add the monomer premix to the polyurethane prepolymer, high-speed stirring, speed 800 rpm, stirring time 15 minutes, forming a stable pre-emulsion;

[0104] Step 4: Free radical polymerization and dispersion

[0105] Polymerization reaction: transfer the pre-emulsion to the polymerization kettle, warm to 75℃, incubate for 3 hours until the monomer conversion rate is ≥98%;

[0106] Water dispersion: cooling to 30℃, slowly add deionized water under high-speed stirring, continue to stir for 30 minutes, forming a translucent aqueous emulsion;

[0107] Step 5: Post-treatment

[0108] Filtration: filter the emulsion through 180 mesh filter cloth to remove possible gel particles.

[0109] A kind of anti-fake kraft paperboard processing device, including pretreatment mechanism 1, double-layer coating mechanism 2, composite mechanism 3, embossing drying mechanism 4, ultraviolet curing mechanism 5 and digital watermark mechanism 6, pretreatment module mechanism 1, double-layer coating mechanism 2, composite mechanism 3, embossing drying mechanism 4, ultraviolet curing mechanism 5 and digital watermark mechanism 6 are sequentially arranged.

[0110] The double-layer coating mechanism 2 comprises an upper coating roller 201 and a lower coating roller 202, the upper coating roller 201 is located above the lower coating roller 202, both ends of the upper coating roller 201 and the lower coating roller 202 are rotationally connected to end plates 203, a rotating groove 204 is arranged between the end plates 203 and behind the upper coating roller 201 and the lower coating roller 202 respectively, a circular-arc-shaped doctor blade 205 is rotationally arranged between the rotating grooves 204, one side of the outer part of the circular-arc-shaped doctor blade 205 behind the upper coating roller 201 is tangent to the outer roller surface of the upper coating roller 201, one side of the outer part of the circular-arc-shaped doctor blade 205 behind the lower coating roller 202 is tangent to the outer roller surface of the lower coating roller 202, when coating, the upper coating roller 201 and the lower coating roller 202 respectively form a ventilation channel 206 with the circular-arc-shaped doctor blade 205 behind the upper coating roller 201 and the lower coating roller 202 and the base paperboard 7, a pulse air jet head 207 is arranged on the end plate 203 and at one end side of the ventilation channel 206, the outer end of the pulse air jet head 207 extends to the outside of the end plate 203, and a discharge port 208 is arranged on the end plate 203 and at the other end side of the ventilation channel 206.

[0111] Adjusting screws 209 are fixedly arranged at the outer sides of the end parts of the circular-arc-shaped doctor blade 205 respectively, arc-shaped sliding grooves 210 are arranged on the end plate 203 and correspond to the positions of the adjusting screws 209, the adjusting screws 209 are slidingly arranged in the inner sides of the arc-shaped sliding grooves 210, and fastening nuts 211 are arranged at the outer sides of the adjusting screws 209.

[0112] Sealing strips 212 are arranged at the tangent positions of the circular-arc-shaped doctor blade 205 and the upper coating roller 201 and the lower coating roller 202.

[0113] Embodiment two

[0114] A processing method of a counterfeit-proof kraft linerboard, comprising the following steps,

[0115] (1) Base material pretreatment: the base paperboard 7 is conveyed to the pretreatment mechanism 1, the spray head performs water-based cleaning at a pressure of 1.6 MPa, the cleaning liquid temperature is 50℃, and the spraying time is 18s;

[0116] (2) Double-layer coating: the upper coating roller 201 of the double-layer coating mechanism 2 coats the temperature-variable ink coating liquid, the color development temperature is 70℃, and the coating amount is 10g / m 2 ; the lower coating roller 202 coats the microcapsule color developer coating liquid, the particle size is 15μm, and the coating thickness is 20μm;

[0117] (3) Composite embossing: after the base material layer and the counterfeit-proof coating layer are combined through the composite mechanism 3, the base material is pressed and dried through the embossing and drying integrated roller of the embossing and drying mechanism 4, the roller pressure is 1.0MPa, the embossing depth is 0.4mm, the infrared heating temperature is 165℃, and the drying time is 38s;

[0118] (4) Multi-layer curing: the UV lamp group of the UV curing mechanism 5 emits 365 nm UV light, and the photoinitiator nozzle 502 synchronously sprays 0.1% concentration initiator with a spraying amount of 0.08 mL / cm 2 , and the curing time is 13 s;

[0119] (5) Anti-counterfeiting embedding: the digital watermark mechanism 6 sprays 12-bit binary code on the edge of the paperboard 7 with an inkjet amount of 0.7 g / m 2 , the code resolution is 600 dpi, and the inkjet height is 4 mm.

[0120] The temperature-variable ink coating solution comprises the following mass percentage components:

[0121] Acetic acid microcapsules 30%

[0122] Water-based PUA emulsion 45%

[0123] Bromocresol purple-p-terephthalic acid composite system 20%

[0124] Dispersant 2%

[0125] Defoaming agent 0.8%

[0126] The molar ratio of bromocresol purple to p-terephthalic acid is 1:1.5.

[0127] The acetic acid microcapsules comprise a core material, an inner layer, and an outer layer,

[0128] The core material is acetic acid;

[0129] The inner layer is a polyurethane acrylic acid and ethylene glycol diacrylate composite oil phase wall material;

[0130] The outer layer is an acetic acid salt aqueous phase wall material.

[0131] The water-based PUA emulsion comprises the following weight components,

[0132]

[0133]

[0134] The preparation method of the water-based PUA emulsion comprises the following steps

[0135] Step 1: Prepolymer synthesis

[0136] Raw material preparation: under the protection of dry nitrogen, polycarbonate diol is added to the reaction kettle, the temperature is raised to 115°C, and vacuum dehydration is performed for 1.7 hours to ensure that the water content is ≤0.05%;

[0137] Isocyanate reaction: the temperature is lowered to 73°C, isophorone diisocyanate is added, 0.05 parts by weight of catalyst is added dropwise, and stirring reaction is performed for 2.7 hours until the NCO content reaches the theoretical value;

[0138] Step 2: Hydrophilic chain extension and neutralization

[0139] Chain extension reaction: cool down to 52℃, add 2,2-dimethylol propionic acid, slowly warm up to 77℃, continue to react for 1.8 hours until the isocyanate group is completely converted;

[0140] Neutralization to salt: cool down to 43℃, add triethylamine, stir for 25 minutes until the carboxylic acid group is completely neutralized, pH is 8, forming ionized polyurethane prepolymer;

[0141] Step 3: Acrylate monomer mixing and pre-emulsification

[0142] Monomer mixing: in another container, mix methyl methacrylate, butyl acrylate, azobisisobutyronitrile uniformly to make a monomer premix;

[0143] Pre-emulsification: slowly add the monomer premix to the polyurethane prepolymer, high-speed stirring, speed 900 rpm, stirring time 18 minutes, forming a stable pre-emulsion;

[0144] Step 4: Free radical polymerization and dispersion

[0145] Polymerization reaction: transfer the pre-emulsion to the polymerization kettle, warm up to 77℃, keep the temperature for 3.5 hours until the monomer conversion rate ≥98%;

[0146] Water dispersion: cool down to 32℃, slowly add deionized water under high-speed stirring, continue to stir for 35 minutes, forming a translucent aqueous emulsion;

[0147] Step 5: Post-treatment

[0148] Filtration: filter the emulsion through a 200-mesh filter cloth to remove possible gel particles.

[0149] A counterfeit-proof kraft paperboard processing device, consistent with the structure of Example One.

[0150] Example Three

[0151] A counterfeit-proof kraft paperboard processing method, comprising the following steps,

[0152] (1) Substrate pretreatment: the substrate paperboard 7 is transported to the pretreatment mechanism 1, and the spray head performs water-based cleaning at a pressure of 1.8 MPa, the cleaning liquid temperature is 55℃, and the spraying time is 20s;

[0153] (2) Double-layer coating: the upper coating roller 201 of the double-layer coating mechanism 2 coats the temperature-changing ink coating liquid, the color developing temperature is 80℃, and the coating amount is 12g / m 2 ; the lower coating roller 202 coats the microcapsule color developing agent coating liquid, the particle size is 20μm, and the coating thickness is 25μm;

[0154] (3) Composite embossing: after the base material layer and the anti-counterfeiting coating are compounded by the compounding mechanism 3, the base material is pressed and dried by the embossing and drying integrated roller of the embossing drying mechanism 4, the roller pressure is 1.2 MPa, the embossing depth is 0.5 mm, the infrared heating temperature is 180℃, and the drying time is 45s;

[0155] (4) Multi-layer curing: the ultraviolet light group of the ultraviolet curing mechanism 5 emits 365nm ultraviolet light, and the light initiator nozzle 502 synchronously sprays 0.1% concentration initiator, the spraying amount is 0.1mL / cm 2 , and the curing time is 15s;

[0156] (5) Anti-counterfeiting embedding: the digital watermark mechanism 6 sprays 12-bit binary code on the edge of the paperboard 7, the inkjet amount is 1.0g / m 2 , the coding resolution is 600dpi, and the inkjet height is 5mm.

[0157] The temperature change ink coating solution comprises the following mass percentage components:

[0158] Acetic acid microcapsules 35%

[0159] Water-based PUA emulsion 50%

[0160] Bromocresol purple-p-terephthalic acid composite system 25%

[0161] Dispersing agent 3%

[0162] Defoaming agent 1%

[0163] The molar ratio of bromocresol purple to p-terephthalic acid is 1:1.8.

[0164] The acetic acid microcapsules comprise a core material, an inner layer and an outer layer,

[0165] The core material is acetic acid;

[0166] The inner layer is a polyurethane acrylic acid and ethylene glycol diacrylate composite oil phase wall material;

[0167] The outer layer is an acetic acid salt water phase wall material.

[0168] The water-based PUA emulsion comprises the following weight components,

[0169]

[0170] The preparation method of the water-based PUA emulsion comprises the following steps

[0171] Step 1: Prepolymer synthesis

[0172] Raw material preparation: under the protection of dry nitrogen, polycarbonate diol is added to the reaction kettle, the temperature is raised to 120℃, and vacuum dehydration is carried out for 2 hours to ensure that the water content is ≤0.05%.

[0173] Isocyanate reaction: cooling to 75℃, adding isophorone diisocyanate, adding 0.05 parts by weight of catalyst dropwise, stirring for 3 hours until the NCO content reaches the theoretical value;

[0174] Step 2: Hydrophilic chain extension and neutralization

[0175] Chain extension reaction: cooling to 55℃, adding 2,2-dimethylol propionic acid, slowly warming to 80℃, continuing to react for 2 hours until the isocyanate group is completely converted;

[0176] Neutralization to form salt: cooling to 45℃, adding triethylamine, stirring for 30 minutes until the carboxylic acid group is completely neutralized, pH is 8.5, forming an ionic polyurethane prepolymer;

[0177] Step 3: Acrylate monomer mixing and pre-emulsification

[0178] Monomer mixing: In another container, mix methyl methacrylate, butyl acrylate, azobisisobutyronitrile uniformly to make a monomer premix;

[0179] Pre-emulsification: Slowly add the monomer premix to the polyurethane prepolymer, high-speed stirring, speed 1000 rpm, stirring time 20 minutes, forming a stable pre-emulsion;

[0180] Step 4: Free radical polymerization and dispersion

[0181] Polymerization reaction: Transfer the pre-emulsion to the polymerization kettle, warm to 80℃, incubate for 4 hours until the monomer conversion rate is ≥98%;

[0182] Water dispersion: cooling to 35℃, slowly adding deionized water under high-speed stirring, continuing to stir for 40 minutes, forming a translucent aqueous emulsion;

[0183] Step 5: Post-treatment

[0184] Filtration: Filter the emulsion through a 220 mesh filter cloth to remove possible gel particles.

[0185] A counterfeit-proof kraft paperboard processing device, which is identical in structure to example one.

[0186] The present application compares the paperboard produced by the above three examples with the paperboard on the market:

[0187] 1. Anti-counterfeiting performance comparison, experimental data as shown in Table 1

[0188] Table 1 Anti-counterfeiting performance comparison data

[0189]

[0190] As can be seen from Table 1, the response speed of the bromocresol purple and terephthalic acid composite system is improved, the double-wall material structure of the microcapsule is improved by about 200% in pressure resistance, the resolution is improved by 100%, the anti-fake information capacity is doubled, the three anti-fake technologies are synergistic, and the identification rate is improved by 30-33%

[0191] 2. Physical property comparison, experimental data as shown in Table 2

[0192] Table 2 Comparison of physical properties of experimental data

[0193]

[0194] As can be seen from Table 2, the combination of polycarbonate diol (PCD) and isophorone diisocyanate (IPDI) has obvious strength improvement; the composite coating structure improves the breaking performance by more than 50%, the PCD hydrophobic segment and MMA water resistance are synergistic, the water absorption rate is reduced, the crosslinking density is optimized, and the color fastness is improved.

[0195] The comparative experiment shows that the technical scheme of the embodiment has obvious improvement in anti-fake performance and physical performance, and the technical indexes are better than those of ordinary products in the market, which has obvious technical innovation and market competitiveness, and is especially suitable for application in high-end brand packaging, anti-fake traceability and other scenes.

[0196] The anti-fake kraft paperboard processing device of the application corresponds to the processing method of the application, the pretreatment mechanism 1, the composite mechanism 3, the embossing and drying mechanism 4, the ultraviolet curing mechanism 5 and the digital watermark mechanism 6 all adopt existing conventional devices, and the application does not make detailed description on this part. In actual coating, the paperboard 7 passes through the pretreatment mechanism 1, the double-layer coating mechanism 2, the composite mechanism 3, the embossing and drying mechanism 4, the ultraviolet curing mechanism 5 and the digital watermark mechanism 6 in turn, and the processing of the paperboard 7 is completed. The double-layer coating mechanism 2 is improved in the application. The upper coating roller 201 coats the temperature-variable ink coating liquid and realizes the thermochromism through the bromocresol purple-p-terephthalic acid composite system. The lower coating roller 202 coats the microcapsule color developing agent, and the acetic acid microcapsule is broken to release the color developing agent under mechanical stress. The double rollers rotate reversely to form a coating gap. The arc-shaped doctor blade plate 205 can control the coating thickness and remove the excess coating liquid. The arc-shaped doctor blade plate 205 can also form an environment isolated from the outside during coating. Under the action of the pulse air jet head 207, the excess coating liquid can be blown away to prevent the accumulation of the coating liquid between the arc-shaped doctor blade plate 205 and the upper coating roller 201. At the same time, the blown coating liquid can be discharged from the discharge port 208, thereby facilitating recycling and reducing waste of the coating liquid. In addition, when not coating and when the angle of rotation of the arc-shaped doctor blade plate 205 is relatively large, the opening on the arc-shaped doctor blade plate 205 can be exposed to the outside, so that the inside of the arc-shaped doctor blade plate 205 and the position between the upper coating roller 201 and the lower coating roller 202 can be easily cleaned for next use. It should be noted that when coating, the upper coating roller 201 and the lower coating roller 202 respectively form a ventilation channel 206 with the arc-shaped doctor blade plate 205 behind them and the base material paperboard. In order to maintain the sealing property of the ventilation channel 206, rubber sealing blocks or rubber sealing strips (not shown) are arranged at the rotating joints of the upper coating roller 201, the lower coating roller 202 and the arc-shaped doctor blade plate 205.

[0197] Finally: the above only describes the preferred embodiments of the application and is not used to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for processing anti-counterfeiting kraft linerboard, characterized by: The following steps are included: (1) Substrate pretreatment: The substrate paperboard is transported to the pretreatment mechanism (1), and the spray head performs water-based cleaning at a pressure of 1.2-1.8 MPa, a cleaning liquid temperature of 45-55°C, and a spraying time of 15-20 seconds; (2) Double-layer coating: The upper coating roller (201) of the double-layer coating mechanism (2) coats the temperature-variable ink coating liquid, with a color development temperature of 60-80°C and a coating amount of 8-12 g / m 2 The lower coating roller (202) is coated with a microcapsule developer coating liquid having a particle size of 10-20 μm and a coating thickness of 15-25 μm; (3) Composite embossing: After the substrate layer and the anti-counterfeiting coating are composited by the composite mechanism (3), the substrate is then pressed by the embossing drying integrated roller of the embossing drying mechanism (4), with a roller pressure of 0.8-1.2 MPa, an embossing depth of 0.3-0.5 mm, an infrared heating temperature of 150-180°C, and a drying time of 30-45 seconds; (4) Multi-layer curing: The UV lamp group of the UV curing mechanism (5) emits 365nm UV light, and the photoinitiator nozzle (502) simultaneously sprays 0.1% concentration initiator with a spray volume of 0.05-0.1mL / cm 2 , curing time 10-15s; (5) Anti-counterfeiting embedding: Digital watermark mechanism (6) Spray 12-bit binary code on the edge of the cardboard, with an inkjet volume of 0.5-1.0g / m 2 , coding resolution 600dpi, printing height 3-5mm.

2. The method for processing anti-counterfeit kraft linerboard according to claim 1, characterized in that: The temperature-variable ink coating liquid includes the following components in percentage by weight: Acetic acid microcapsules 25-35% Water-based PUA emulsion 40-50% Bromocresol purple-terephthalic acid composite system 15-25% Dispersant 1-3% Defoaming agent 0.5-1% The molar ratio of bromocresol purple to terephthalic acid is 1:1.2-1.

8.

3. The method for processing anti-counterfeit kraft linerboard according to claim 2, characterized in that: The acetic acid microcapsules include a core material, an inner layer and an outer layer. The core material is acetic acid; The inner layer is a composite oil-phase wall material of polyurethane acrylic acid and ethylene glycol diacrylate; The outer layer is acetate aqueous phase wall material.

4. The method for processing anti-counterfeit kraft linerboard according to claim 2, characterized in that: The aqueous PUA emulsion comprises the following components in parts by weight:

5. The method for processing anti-counterfeit kraft linerboard according to claim 4, characterized in that: The preparation method of the aqueous PUA emulsion comprises the following steps: Step 1: Prepolymer synthesis Raw material preparation: under the protection of dry nitrogen, add polycarbonate diol into the reactor, heat to 110-120℃, and vacuum dehydrate for 1.5-2 hours to ensure that the water content is ≤0.05%; Isocyanate reaction: cool to 70-75°C, add isophorone diisocyanate, dropwise add 0.05 parts by weight of catalyst, and stir to react for 2.5-3 hours until the NCO content reaches the theoretical value; Step 2: Hydrophilic chain extension and neutralization Chain extension reaction: cool down to 50-55℃, add 2,2-dimethylolpropionic acid, slowly raise the temperature to 75-80℃, and continue the reaction for 1.5-2 hours until the isocyanate groups are completely converted; Neutralization to salt: cool to 40-45°C, add triethylamine, and stir for 20-30 minutes until the carboxylic acid groups are completely neutralized and the pH is 7.5-8.5 to form an ionized polyurethane prepolymer; Step 3: Acrylate Monomer Mixing and Pre-emulsification Monomer mixing: In another container, mix methyl methacrylate, butyl acrylate, and azobisisobutyronitrile to prepare a monomer premix; Pre-emulsification: slowly add the monomer premix to the polyurethane prepolymer, stirring at high speed, speed 800-1000 rpm, stirring time 15-20 minutes, to form a stable pre-emulsion; Step 4: Free Radical Polymerization and Dispersion Polymerization reaction: transfer the pre-emulsion to the polymerization kettle, raise the temperature to 75-80℃, and keep the temperature to react for 3-4 hours until the monomer conversion rate is ≥98%; Water dispersion: Cool to 30-35°C, slowly add deionized water under high-speed stirring, and continue stirring for 30-40 minutes to form a translucent aqueous emulsion; Step 5: Post-processing Filtration: Filter the emulsion through a 180-220 mesh filter cloth to remove any gel particles that may be present.

6. The anti-counterfeiting kraft linerboard processing device according to claim 1, characterized in that: The invention comprises a pre-processing mechanism (1), a double-layer coating mechanism (2), a compounding mechanism (3), an embossing and drying mechanism (4), an ultraviolet curing mechanism (5) and a digital watermarking mechanism (6), wherein the pre-processing module mechanism (1), the double-layer coating mechanism (2), the compounding mechanism (3), the embossing and drying mechanism (4), the ultraviolet curing mechanism (5) and the digital watermarking mechanism (6) are arranged in sequence.

7. The anti-counterfeit kraft linerboard processing device according to claim 6, characterized in that: The double-layer coating mechanism (2) comprises an upper coating roller (201) and a lower coating roller (202), wherein the upper coating roller (201) is located above the lower coating roller (202), and the ends of the upper coating roller (201) and the lower coating roller (202) are rotatably connected to the end plate (203), and a rotation groove (204) is provided between the end plates (203) and respectively located behind the upper coating roller (201) and the lower coating roller (202), and an arc-shaped scraper (205) is rotatably provided between the rotation grooves (204), and the outer side of the arc-shaped scraper plate (205) behind the upper coating roller (201) is tangent to the outer roller surface of the upper coating roller (201). The outer side of one side of the arc-shaped scraper plate (205) behind the lower coating roller (202) is tangent to the outer roller surface of the lower coating roller (202). When coating, the upper coating roller (201) and the lower coating roller (202) respectively form a ventilation channel (206) with the arc-shaped scraper plate (205) behind them and the substrate paperboard. A pulse air jet head (207) is provided on the end plate (203) and located at one end side of the ventilation channel (206). The outer end of the pulse air jet head (207) extends to the outside of the end plate (203). A discharge port (208) is provided on the end plate (203) and located at the other end side of the ventilation channel (206).

8. The anti-counterfeiting kraft linerboard processing device according to claim 7, characterized in that: Adjustment screws (209) are fixedly arranged on the outer sides of the ends of the arc-shaped scraper plate (205), and an arc-shaped sliding groove (210) is arranged on the end plate (203) at a position corresponding to the adjustment screw (209). The adjustment screw (209) is slidably arranged on the inner side of the arc-shaped sliding groove (210), and a fastening nut (211) is arranged on the outer side of the adjustment screw (209).

9. The anti-counterfeit kraft linerboard processing device according to claim 7, characterized in that: A sealing strip (212) is provided at the location where the arc-shaped scraper plate (205) is tangent to the upper coating roller (201) and the lower coating roller (202).

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