Substrate and method of making, coating removal method, and security structure

Abstract

The application discloses a substrate and a preparation method thereof, a coating removal method and an anti-fake structure. The substrate comprises a base layer and a removable layer which are arranged in a stack. The removable layer comprises a film-forming substance. The film-forming substance can be thermally dissociated under a specific environment. After the film-forming substance is thermally dissociated, the removable layer can be removed. The substrate described above, the film-forming substance in the removable layer can be degraded by heating under a specific humidity environment, and after the film-forming substance is degraded, the removable layer can be removed. When the substrate is used for proofing printing, after the removable layer is removed, the base layer can be reused, thereby greatly reducing the proofing cost of a printing enterprise. The preparation method of the substrate is used for preparing the substrate, and the coating removal method is used for removing the removable layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a substrate and a preparation method thereof, a coating removal method and an anti-counterfeiting structure. BACKGROUND

[0002] In the prior art, coating containing water-based film-forming substances (such as water-based varnish) is widely used in the surface treatment of printed matter, and a coating layer is formed on the surface of printed graphics to protect the printed graphics layer. Since the printed matter may be subjected to a high-temperature and high-humidity environment in a summer warehouse or container, the coating needs to have high stability, including excellent high-temperature dissociation resistance and moisture resistance. If the above properties do not meet the standards, it will lead to serious quality accidents. To verify the stability, it is usually required to do a reverse adhesion test in a high-temperature and high-humidity environment of 70°C and 90% humidity. Therefore, how to prevent the coating containing water-based film-forming substances from thermal dissociation at high temperatures is a technical problem that must be overcome by those skilled in the art.

[0003] In the prior art, foamed materials are widely used in the preparation of foamed graphics in the field of clothing. Since the clothing needs to be in contact with water for a long time during washing and is subjected to a large amount of friction, the foamed graphics are required to have good adhesion and water resistance. If the above properties do not meet the standards, it will lead to quality accidents.

[0004] In the offset printing, intaglio printing, silk printing or flexographic printing process, the graphics layer formed by the printing ink is in direct contact with the substrate, and the ink has the characteristics of permeability, thin ink layer and high adhesion. Therefore, the graphics layer on the substrate cannot be removed, which leads to the fact that a large amount of substrate used in the printing process cannot be reused, thereby increasing the cost pressure on the printing enterprise.

[0005] Therefore, it is necessary to provide a substrate and a preparation method thereof, a coating removal method and an anti-counterfeiting structure to solve the above problems. SUMMARY

[0006] The first aspect of the present application provides a substrate.

[0007] A substrate comprises:

[0008] a base layer; and

[0009] a removable layer, which is stacked on the base layer, the removable layer comprising a film-forming substance, the film-forming substance being capable of thermal dissociation in a specific environment, the film-forming substance having reduced adhesion after thermal dissociation, and the removable layer being removable.

[0010] In one embodiment, the specific environment is a wet heating environment, and the thermal dissociation is thermal swelling dissociation.

[0011] In one embodiment, the removable layer comprises a foamed material, the specific environment is a dry heating environment, and the thermally induced dissociation is a thermally induced rupturing dissociation.

[0012] In one embodiment, the film-forming material is an aqueous film-forming material.

[0013] In one embodiment, the aqueous film-forming material is selected from at least one of polyurethane resin, acrylic resin, polyvinyl alcohol and modified resin thereof, polyethylene oxide-based resin, starch and derivatives thereof, polyvinylpyrrolidone, and environmentally responsive block copolymer.

[0014] In one embodiment, the removable layer comprises a foamed material.

[0015] In one embodiment, the specific environment is a wet heating environment, and the thermally induced dissociation is a thermally induced swelling dissociation and a thermally induced rupturing dissociation.

[0016] In one embodiment, the wet heating environment is a steam heating environment, and the thermally induced dissociation is a moderate thermally induced swelling dissociation and a full thermally induced rupturing dissociation.

[0017] In one embodiment, the specific environment comprises a dry heating environment and a wet heating environment in sequence, and the thermally induced dissociation comprises a thermally induced rupturing dissociation and a thermally induced swelling dissociation in sequence.

[0018] In one embodiment, the removable layer further comprises a water-containing material, the specific environment is a dry heating environment, and the thermally induced dissociation is a thermally induced rupturing dissociation and a low thermally induced swelling dissociation.

[0019] In one embodiment, the side of the removable layer away from the base layer is provided with a barrier layer.

[0020] In one embodiment, the foamed material is a hybrid foamed material.

[0021] In one embodiment, the foamed material is selected from at least one of a physical foamed material, a chemical foamed material, an inorganic foamed material, an environmentally friendly foamed material, and a composite foamed material.

[0022] In one embodiment, the physical foaming material is selected from any one of a volatile liquid, a compressed gas, a supercritical fluid, a foaming microsphere, expanded graphite, vermiculite powder, and expanded hexagonal boron nitride; the chemical foaming material is selected from any one of an azo-based foaming material, a sulfonhydrazide-based foaming material, a carbonate-based foaming material, a hydrazine-based / acrid hydrazide-based foaming material, a hydrazine-based / acrid hydrazide-based foaming material, and a reaction-type foaming material; the inorganic foaming material is selected from any one of a carbonate-based foaming material, a metal hydride foaming material, and a silicate-based foaming material; the environmentally friendly foaming material is selected from any one of a bio-based foaming material, an HFOs foaming material, and a natural product foaming material; and the composite foaming material is selected from any one of an endothermic-exothermic composite foaming material, an acid-base reaction-type foaming material, and a metal-organic composite foaming material.

[0023] In one embodiment, the foaming material has a specific heuristic temperature, and the heuristic temperature is 60-200℃.

[0024] In one embodiment, the thickness of the removable layer is 0.001-1mm.

[0025] In one embodiment, the substrate layer is paper, a polymer sheet, a metal sheet, or a composite material.

[0026] The substrate described above comprises a film-forming substance in the removable layer, the film-forming substance can be thermally dissociated under a specific environment, the film-forming substance is thermally dissociated, the adhesion is greatly reduced, and the removable layer can be removed. When the substrate is used for proofing printing, after the removable layer is removed, the substrate layer can be reused, thereby greatly reducing the proofing cost of the printing enterprise.

[0027] The second aspect of the present application provides a preparation method of a substrate.

[0028] The preparation method of a substrate comprises:

[0029] Step S1: disposing a removable layer on a substrate layer;

[0030] The removable layer comprises a film-forming substance, the film-forming substance can be thermally dissociated under a specific environment, the film-forming substance is thermally dissociated, the adhesion is greatly reduced, and the removable layer can be removed.

[0031] In one embodiment, after the step S1, further comprising:

[0032] Step S2: the removable layer 20 comprises a foaming material, and the foaming material is thermally dissociated by dry heating.

[0033] The third aspect of the present application provides a coating removal method.

[0034] A coating removal method, implemented on a substrate according to any one of the first aspects of the present invention, includes the following steps:

[0035] The film-forming substance undergoes thermal dissociation under specific conditions;

[0036] Remove the movable layer.

[0037] In one embodiment, the removal method is selected from any one of scraping removal, brush removal, vibration peeling, negative pressure suction or airflow blowing.

[0038] A fourth aspect of the present invention provides an anti-counterfeiting structure.

[0039] An anti-counterfeiting structure includes a substrate, on which a printed graphic layer is disposed, wherein the substrate is the substrate described in any one of the first aspects of the present invention. Attached Figure Description

[0040] Figure 1 A schematic diagram of the layered structure of a substrate according to one embodiment;

[0041] Figure 2 A flowchart illustrating a method for preparing a substrate according to one embodiment;

[0042] Figure 3 A flowchart illustrating a method for preparing a substrate according to another embodiment;

[0043] Figure 4 A flowchart illustrating one embodiment of a coating removal method;

[0044] Figure 5 Here is a flowchart of a coating removal method according to another embodiment; Detailed Implementation

[0045] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] It is to be understood that where an element such as a layer, region or substrate is described as being "on" another element, it can be directly on the other element or intervening elements can also be present. Where an element such as a layer, region or substrate is described as being "connected" or "coupled" to another element, it can be directly connected to the other element or intervening elements can also be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0047] The substrate and the method for manufacturing the same and the coating removal method will be further described in detail below mainly in conjunction with the drawings and specific embodiments.

[0048] Referring to Figure 1 The substrate of an embodiment includes a base layer 10 and a removable layer 20 arranged in a stack.

[0049] The base layer 10 is used to carry the removable layer 20. Generally, the base layer 10 has a higher purchase cost and has a higher value for repeated use. When the purchase cost of the base layer 10 is greater than the removal cost and the arrangement cost of the removable layer 20, it is economical to use the base layer 10 as the base layer 10.

[0050] Optionally, the material of the base layer 10 includes but is not limited to paper, polymer sheet, metal sheet or composite material.

[0051] In the embodiment, the base layer 10 is paper. Paper is often used as a printing material for packaging boxes and picture albums.

[0052] Optionally, the paper is copper paper, white cardboard, gray cardboard, gold cardboard or silver cardboard.

[0053] Preferably, the paper has a grammage greater than or equal to 150 g / m2.

[0054] Preferably, when the base layer 10 is paper, a first protective material is arranged on the first surface of the base layer 10 close to the removable layer 20. The first protective material is used to protect the first surface of the base layer 10. On the one hand, it can prevent moisture from entering the base layer 10 through the first surface. On the other hand, it can prevent the first surface from being damaged by a removal tool in the subsequent process of removing the removable layer 20, thereby prolonging the service life of the base layer 10.

[0055] Optionally, the first protective material includes but is not limited to water-based varnish, UV varnish, polymer film, aluminum foil and aluminum plastic composite film.

[0056] Preferably, a second protective material is arranged on the second surface of the substrate layer 10 away from the movable layer 20. By arranging the second protective material, water vapor can be prevented from entering the substrate layer 10 through the second surface, so as to prevent the substrate layer 10 from being deformed due to water absorption, thereby protecting the substrate layer 10 and prolonging the service life thereof.

[0057] Optionally, the second protective material includes but is not limited to water-based varnish, UV varnish, paraffin, polymer film, aluminum foil and aluminum plastic composite film.

[0058] Preferably, a third protective material is arranged on the four sections of the substrate layer 10. By arranging the third protective material, water vapor can be prevented from entering the substrate layer 10 through the four sections, thereby greatly prolonging the service life of the substrate layer 10. The third protective material can be arranged by means of brushing or spraying.

[0059] Optionally, the third protective material includes but is not limited to UV varnish, paraffin or other waterproof paint.

[0060] In another embodiment, the substrate layer 10 is a polymer sheet. The polymer sheet has a high procurement cost and is often used as a printing material for cosmetic packaging boxes.

[0061] Optionally, the polymer sheet includes but is not limited to PP sheet, PET sheet, PS sheet, PE sheet, OPS sheet and PVC sheet.

[0062] In another embodiment, the substrate layer 10 is a metal sheet. The metal sheet has a high procurement cost and is often used as a printing material for container packaging or ointment packaging.

[0063] Optionally, the metal sheet includes but is not limited to iron sheet, aluminum sheet, copper sheet and stainless steel sheet.

[0064] In another embodiment, the substrate layer 10 is an aluminum plastic composite material. The aluminum plastic composite material has a high procurement cost and is widely used in medical packaging materials, food packaging and daily chemical packaging.

[0065] Optionally, the composite material includes but is not limited to paper-plastic composite material, aluminum-plastic composite material and composite material between different polymer materials.

[0066] Optionally, the shape of the substrate layer 10 is quadrilateral.

[0067] Preferably, the shape of the substrate layer 10 is pentagonal or hexagonal. The pentagonal or hexagonal shape can be obtained by cutting one or two right angles of the substrate layer 10. When the substrate is used for color proofing printing, the substrate can be quickly identified by the shape difference.

[0068] It should be understood that the base layer 10 can be in a single sheet form or a roll form, both of which are common forms of printed materials.

[0069] The removable layer 20 is laminated on the base layer 10, and is obtained by drying a coating or ink containing a film-forming material. During the drying process, the film-forming material is physically fused or chemically cross-linked to form a dense removable layer 20, so that the removable layer 20 can be firmly attached to the surface of the base layer 10. However, in a specific environment, the film-forming material that has been physically fused or chemically cross-linked can undergo thermal-induced dissociation. After thermal-induced dissociation, the molecular weight of the film-forming material is greatly reduced, and the adhesion is greatly reduced, so that the removable layer 20 can be removed.

[0070] In the present application, the specific environment includes a dry heating environment and a wet heating environment, and the thermal-induced dissociation includes thermal-induced rupture dissociation and thermal-induced swelling dissociation.

[0071] In the present embodiment, the specific environment is a wet heating environment, and the thermal-induced dissociation is thermal-induced swelling dissociation, which is manifested as the film-forming material with a three-dimensional network structure swelling or even dissolving in a high-temperature liquid in a wet heating environment.

[0072] Specifically, during the drying of the film, on the one hand, the hydrophobic groups (such as long-chain alkyl groups, fluorine / silicon modified groups) in the aqueous film-forming material are closely arranged after the evaporation of water, forming a dense cross-linked network structure, which can effectively block the penetration of water. On the other hand, the aqueous film-forming material contains a small amount of hydrophilic groups (such as carboxylic acid groups, hydroxyl groups), but these hydrophilic groups will be wrapped by hydrophobic segments or fixed by cross-linking reaction during the film-forming process, and cannot fully contact with water molecules, so the removable layer 20 exhibits strong water resistance at room temperature.

[0073] Surprisingly, it is found that some waterborne film-forming materials which have been physically fused or chemically cross-linked can be thermally induced to swell and dissociate in a wet heating environment, because: (1) high temperature can activate and destroy the cross-linking structure of the film-forming material. Specifically, the energy provided by the wet heating environment can destroy the secondary forces such as hydrogen bonds, van der Waals forces, etc. between the waterborne film-forming material molecules, resulting in the loosening of the cross-linked network. If the waterborne film-forming material contains thermosensitive groups such as ester groups and ether bonds, the wet heating environment can also cause chemical bond rupture, leading to the collapse of the film structure. (2) Exposure of hydrophilic groups and swelling. The chain segment movement of the waterborne film-forming material is intensified in the wet heating environment, and the originally wrapped hydrophilic groups are exposed again to form hydrogen bonds with water molecules, triggering the thermally induced swelling and dissociation of the removable layer 20. When the thermally induced swelling and dissociation is moderate, the removable layer 20 softens, and the adhesion is greatly reduced; when the thermally induced swelling and dissociation is sufficient, the removable layer 20 is colloidal; when the swelling degree exceeds the bearing limit of the cross-linked network, the removable layer 20 can even gradually dissolve in hot water, so the removable layer 20 after thermally induced swelling and dissociation can be removed by scraping or directly removed by dissolving the removable layer 20.

[0074] It should be noted that thermally induced swelling and dissociation only causes the hydrogen bonds of the film-forming material molecules to break, so the thermally induced swelling and dissociation is partially reversible. When the water is dried, the removable layer 20 can recover the film structure, but the adhesion will be greatly reduced, so it can be removed.

[0075] Alternatively, the material of the waterborne film-forming material includes but is not limited to polyurethane resin, acrylic resin, polyvinyl alcohol and modified resin thereof, polyethylene oxide-based resin, starch and its derivatives, polyvinylpyrrolidone, and environmentally responsive block copolymer.

[0076] Further, the waterborne film-forming material containing ester groups includes but is not limited to polyurethane resin, acrylic resin, polyvinyl alcohol and modified resin thereof, starch and its derivatives. The waterborne film-forming material containing ether bonds includes but is not limited to polyurethane resin, polyvinyl alcohol and modified resin thereof, polyethylene oxide-based resin, starch and its derivatives.

[0077] Further, the waterborne paint is waterborne varnish, waterborne gloss oil or waterborne ink. The waterborne varnish, waterborne gloss oil and waterborne ink usually use polyurethane resin or acrylic resin as the film-forming material, so they can be directly used to prepare the removable layer 20.

[0078] Alternatively, the wet heating is water bath heating, steam heating or liquid film heating.

[0079] Preferably, the wet heating is steam heating, which can cause the removable layer 20 to undergo moderate thermally induced swelling and dissociation within 2-4 seconds, so that the removable layer 20 can be efficiently removed by scraping.

[0080] In another embodiment, the specific environment is a dry heating environment, and the thermal-induced dissociation is a thermal-induced rupture dissociation, which is internally manifested as the molecular chain rupture of the film-forming substance under the action of internal stress, and externally manifested as the appearance of a large number of micro-pores in the removable layer 20, the substantial volume expansion, and the substantial reduction of the adhesive force, so that the removable layer 20 can be removed by an external force.

[0081] Specifically, the removable layer 20 contains a foaming material, and the foaming material generates internal stress in the removable layer 20 during the foaming process. The three-dimensional network molecular structure of the film-forming substance is ruptured under the action of the internal stress, so that the molecular weight of the film-forming substance is substantially reduced, and the adhesive force is substantially reduced, so that the removable layer 20 can be removed from the base layer 10.

[0082] The foaming material contains a heat-sensitive component. When the ambient temperature is higher than the trigger temperature of the heat-sensitive component, the heat-sensitive component releases a large amount of gas through decomposition, evaporation or sublimation. The gas directly or indirectly generates internal stress in the removable layer 20. The internal stress can cause the molecular chain of the film-forming substance in the removable layer 20 to rupture, the molecular weight is substantially reduced, and a large number of pores are generated in the removable layer 20, the volume is expanded, so that the adhesive force between the removable layer 20 and the base layer 10 is substantially reduced, and the removable layer 20 can be removed from the base layer 10.

[0083] It should be noted that the thermal-induced rupture dissociation causes the chemical bond rupture of the molecules of the film-forming substance, and therefore, the damage caused by the thermal-induced rupture dissociation is irreversible.

[0084] In some embodiments, the foaming material is in the form of particles. During the process of releasing gas by the heat-sensitive component, the gas causes the volume of the foaming material particles to expand, and the internal stress is indirectly provided by the outer surface of the foaming material particles. In some other embodiments, the foaming material is dissolved and dispersed in the base layer 10, and the internal stress is directly provided by the gas molecules released.

[0085] Optionally, the foaming material can be classified into: physical foaming material, chemical foaming material, inorganic foaming material, environmentally friendly foaming material, and composite foaming material.

[0086] Specifically, the physical foaming material includes but is not limited to: volatile liquid, compressed gas, supercritical fluid, foaming microsphere, expanded graphite, vermiculite powder, and expanded hexagonal boron nitride.

[0087] Optionally, the volatile liquid foaming material includes but is not limited to: pentane (C5H 21 ), butane (C4H 10), dichloromethane (CH2Cl2), HFC-134a. Compressed gas blowing materials include but are not limited to: nitrogen (N2), carbon dioxide (CO2), air. Supercritical fluid blowing materials include but are not limited to: supercritical carbon dioxide (scCO2), supercritical nitrogen (scN2), supercritical argon (scAr).

[0088] Chemical blowing materials include but are not limited to: azo-based blowing materials, sulfonyl hydrazide-based blowing materials, carbonate-based blowing materials, hydrazine-based / acetylhydrazine-based blowing materials, hydrazine-based / acetylhydrazine-based blowing materials, reaction-type blowing materials.

[0089] Specifically, azo-based blowing materials include but are not limited to: azodicarbonamide (AC), azobisisobutyronitrile (AIBN), barium azodicarboxylate (BAB), and azodicarbonic ester (ADC). Sulfonyl hydrazide-based blowing materials include but are not limited to: p-toluenesulfonyl hydrazide (TSH), benzene sulfonyl hydrazide (BSH), and diphenyl sulfone-3,3'-disulfonyl hydrazide (DPSH). Carbonate-based blowing materials include but are not limited to: sodium bicarbonate (NaHCO3), ammonium bicarbonate (NH4HCO3), and ammonium carbonate ((NH4)2CO3). Nitro / nitroso-based blowing materials include but are not limited to: nitrosopentamethylene tetramine (blowing material H), nitroguanidine (NG), 2,2'-dinitrobenzene (DNB). Hydrazine-based / acetylhydrazine-based blowing materials include but are not limited to: 4,4'-oxobisbenzenesulfonyl hydrazide (OBSH), trihydrazinotriazine (THT), 5-phenyltetrazole (5-PT). Reaction-type blowing materials include but are not limited to: water (H2O, polyurethane), hydrogen peroxide (H2O2, rubber blowing), isocyanate self-reaction system.

[0090] Inorganic blowing materials include but are not limited to: carbonate-based blowing materials, metal hydride blowing materials, and silicate-based blowing materials.

[0091] Specifically, carbonate-based blowing materials include but are not limited to: magnesium carbonate (MgCO3), calcium carbonate (CaCO3), zinc carbonate (ZnCO3). Metal hydride blowing materials include but are not limited to: aluminum hydride (AlH3), magnesium hydride (MgH2), sodium borohydride (NaBH4). Silicate-based blowing materials include but are not limited to: water glass (Na2SiO3), bentonite.

[0092] Environmentally friendly blowing materials include but are not limited to: bio-based blowing materials, HFOs blowing materials, natural product blowing materials.

[0093] Specifically, the bio-based foaming material includes, but is not limited to, polylactic acid (PLA) microspheres, starch-based particles, and cellulose foaming material. The HFOs foaming material includes, but is not limited to, HFO-1234ze, HFO-1336mzz, and HFO-1233zd. The natural product foaming material includes, but is not limited to, coconut oil derivatives and soybean oil-based polyols.

[0094] The composite foaming material includes, but is not limited to, heat-absorbing and heat-releasing composite foaming material, acid-base reaction foaming material, and metal-organic composite foaming material.

[0095] Specifically, the heat-absorbing and heat-releasing composite foaming material includes, but is not limited to, sodium bicarbonate and azodicarbonamide, citric acid and sodium bicarbonate. The acid-base reaction foaming material includes, but is not limited to, calcium carbonate and stearic acid, zinc oxide and stearic acid. The metal-organic composite foaming material includes, but is not limited to, aluminum hydride and polysiloxane, magnesium carbonate and azo.

[0096] In one embodiment, the foaming material is foaming microspheres having a core-shell structure of a high-molecular outer shell and a foaming agent inner core. When the temperature is higher than the trigger temperature of the foaming agent inner core, on the one hand, the high-molecular outer shell softens, and on the other hand, the foaming agent inner core releases a large amount of gas. Under the pressure of the inner core, the volume of the foaming microspheres expands sharply, thereby generating indirect internal stress in the removable layer 20 through the outer shell and causing the removable layer 20 to undergo thermal-induced break-up dissociation. The foamed foaming microspheres are in the form of hollow spheres.

[0097] In another embodiment, the foaming material is expanded graphite. The graphite molecules have a parallel hierarchical structure, and the molecules between the hierarchies are combined by van der Waals force. The expanded graphite is expanded by inserting an expanding agent between the hierarchical molecules. When the ambient temperature is higher than the trigger temperature of the expanding agent, the expanding agent decomposes and releases a large amount of gas. The pressure generated by the gas pushes the graphite molecules between the hierarchies to expand sharply along the axial direction, thereby generating internal stress in the removable layer 20 and causing the removable layer 20 to undergo thermal-induced break-up dissociation. The expanded expanded graphite is in the form of popcorn.

[0098] It should be understood that when the foaming material is expanded graphite, the removable layer 20 is gray or black due to the black appearance of the expanded graphite. Before performing the proofing printing, a base color layer can be arranged on the surface of the removable layer 20, so that the substrate has the correct color.

[0099] In another embodiment, the foaming material is modified sodium bicarbonate. The outer surface of the modified sodium bicarbonate particles is coated with a hydrophobic layer. When the ambient temperature is higher than the trigger temperature of 60°C, the modified sodium bicarbonate particles can decompose to generate a large amount of carbon dioxide gas, thereby generating internal stress in the removable layer 20 and causing the removable layer 20 to undergo thermal-induced break-up dissociation.

[0100] In another embodiment, the foaming material is azobisisobutyronitrile, the azobisisobutyronitrile particles are insoluble in water, and the azobisisobutyronitrile particles have an activation temperature of 90-115°C. When the ambient temperature is higher than the activation temperature, the azobisisobutyronitrile particles can decompose to generate a large amount of nitrogen gas, and a large amount of gas can be generated in the removable layer 20, thereby generating internal stress in the removable layer 20, and causing the removable layer 20 to undergo thermal-induced fracture dissociation.

[0101] In another embodiment, the foaming material is p-toluenesulfonyl hydrazide, the p-toluenesulfonyl hydrazide particles are insoluble in water, and the p-toluenesulfonyl hydrazide particles have an activation temperature of 110-130°C. When the ambient temperature is higher than the activation temperature, the p-toluenesulfonyl hydrazide particles can decompose to generate a large amount of nitrogen gas, and a large amount of gas can be generated in the removable layer 20, thereby generating internal stress in the removable layer 20, and causing the removable layer 20 to undergo thermal-induced fracture dissociation.

[0102] In another embodiment, the foaming material is 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH), the OBSH particles are insoluble in water, and the OBSH particles have an activation temperature of 150-160°C. When the ambient temperature is higher than the activation temperature, the OBSH particles can decompose to generate a large amount of nitrogen gas and water vapor, and a large amount of gas can be generated in the removable layer 20, thereby generating internal stress in the removable layer 20, and causing the removable layer 20 to undergo thermal-induced fracture dissociation. OBSH particles are widely used in TPU and shoe material foaming process. It is worth noting that the water vapor generated during the OBSH foaming process can trigger the thermal-induced swelling dissociation of the water-based film-forming material, and the double dissociation helps to promote the removal of the removable layer 20.

[0103] In another embodiment, the foaming material is azobisisobutyronitrile, the azobisisobutyronitrile particles are insoluble in water, and the azobisisobutyronitrile particles have an activation temperature of 90-115°C. When the ambient temperature is higher than the activation temperature, the azobisisobutyronitrile particles can decompose to generate a large amount of nitrogen gas, and a large amount of gas can be generated in the removable layer 20, thereby generating internal stress in the removable layer 20, and causing the removable layer 20 to undergo thermal-induced fracture dissociation.

[0104] In another embodiment, the foaming material is a mixed foaming material, the mixed foaming material includes a first foaming material and a second foaming material, the first foaming material has a first activation temperature, the second foaming material has a second activation temperature, and the second activation temperature is higher than the first activation temperature. When the ambient temperature is higher than the first activation temperature, the first foaming material foams, allowing the removable layer 20 to generate pores while still maintaining a relatively high adhesive force, allowing ordinary offset ink to penetrate and dry in the removable layer 20, but not allowing the removable layer 20 to fall off during printing. When the ambient temperature is higher than the second activation temperature, the second foaming material foams, greatly reducing the adhesive force of the removable layer 20, so that the removable layer 20 can be removed.

[0105] Optionally, the foamed material has a particle size of 1 micron to 50 microns. The foamed material having a particle size in this range is used to prepare the water-based coating, which can be applied by offset printing, intaglio printing, silk printing or coating.

[0106] Optionally, the foamed material has an onset temperature of 60°C to 200°C. The onset temperature in this range is relatively low, and the substrate layer 10 is less likely to be deformed when the foamed material is initiated.

[0107] Preferably, the foamed material has an onset temperature of 70°C to 130°C. On the one hand, when the substrate layer 10 is made of paper, the deformation of the substrate layer 10 can be controlled within a lower range at this temperature. On the other hand, the foamed material is prevented from initiating foaming when the high-temperature anti-sticking test is performed.

[0108] It should be understood that when the thermal-induced dissociation is thermal-induced fracture dissociation, the removable layer 20 is only subjected to internal stress to achieve thermal-induced fracture dissociation, and therefore, the property of the film-forming substance is not limited, and the film-forming substance can be a water-based film-forming substance, an oil-based film-forming substance or other types of film-forming substances.

[0109] Optionally, the dry heating environment includes, but is not limited to, infrared heating, ironing heating, ultrasonic heating and plasma heating.

[0110] However, it should be noted that during the dry heating process, the temperature has both positive and negative effects on the adhesion of the removable layer 20. On the one hand, high temperature promotes the full cross-linking and curing of the film-forming substance in the removable layer 20, so that a dense three-dimensional network structure is formed, thereby increasing the adhesion of the removable layer 20 to a certain extent. On the other hand, the foamed material is tightly wrapped by the highly cross-linked film-forming substance in the removable layer 20, and the foaming of the foamed material generates internal stress in the removable layer 20, which can have two possible results:

[0111] (1) When the high-temperature strengthening effect is greater than the internal stress destruction effect, the internal stress has limited damage to the hierarchical structure of the removable layer 20, and therefore, the removable layer 20 still maintains a high adhesion. It is found through experiments that when the environmental temperature is higher than 130°C in the dry heating environment, the high-temperature strengthening effect is greater than the internal stress destruction effect, and the removable layer 20 still maintains a high adhesion. Although the removable layer 20 can be removed, it is difficult to remove.

[0112] (2) When the high-temperature strengthening effect is less than the internal stress destruction effect, the internal stress will directly destroy the hierarchical structure of the removable layer 20, cause the molecular chains of the water-based film-forming substance in the removable layer 20 to break, greatly reduce the molecular weight, and generate a large number of pores in the removable layer 20, thereby greatly reducing the adhesion between the removable layer 20 and the base layer 10, but the removable layer 20 still maintains the integrity of the hierarchical structure. At this time, the removable layer 20 can be removed, but the removal efficiency is relatively low. Experiments have found that, in a dry heating environment, when the ambient temperature is lower than 130°C, the high-temperature strengthening effect is less than the internal stress destruction effect.

[0113] It should be noted that, in order to maintain the adhesion of the foaming process, the prior art usually adopts a pressing and heating method belonging to dry heating to heat the foaming coating. On the one hand, the pressing temperature is usually higher than 130°C, the high-temperature strengthening effect is less than the internal stress destruction effect, and therefore the foaming coating can maintain relatively high adhesion. On the other hand, the pressure applied by the pressing plate can inhibit the degree of thermal-induced rupture dissociation of the foaming coating, thereby ensuring that the foaming coating has relatively high adhesion.

[0114] In another embodiment, the specific environment is a dry heating environment, and the thermal-induced dissociation includes two forms of thermal-induced rupture dissociation and thermal-induced swelling dissociation.

[0115] Specifically, the removable layer 20 contains both foaming material and water-containing material. When the ambient temperature is higher than the foaming temperature, the internal stress generated by the foaming of the foaming material can cause the removable layer 20 to undergo thermal-induced rupture dissociation. The water-containing material contains free water or crystal water, and the water-containing material can release water molecules at high temperature. The water molecules can undergo low-intensity thermal-induced swelling dissociation with the water-based film-forming substance. Under the synergistic effect of thermal-induced rupture dissociation and low-intensity thermal-induced swelling dissociation, the adhesion of the removable layer 20 can be greatly reduced, thereby making the removable layer 20 removable.

[0116] The application scenario of this embodiment is: in the field of traditional tinplate printing, the ink is a thermosetting ink, and after printing, it needs to be baked at a high temperature environment of 130-170°C for 10-15 minutes. When the removable layer 20 only contains the foaming material, the heating time required for foaming of the foaming material is much less than the drying time of the thermosetting ink. When the foaming material is completely foamed, the thermosetting ink has not yet dried, and it still has good flexibility. The layered ink layer can maintain an intact hierarchical structure through tensile deformation, and external water vapor cannot penetrate the ink layer to reach the removable layer 20, so the removable layer 20 only undergoes thermal-induced fracture dissociation. At the same time, since the drying temperature is higher than 130°C, the high temperature will promote the crosslinking of the film-forming material. Overall, the internal stress generated by the foaming material will be less than the chemical bond energy of the three-dimensional network structure, so the removable layer 20 still maintains a relatively high adhesion. Although the removable layer 20 can be removed, it is difficult to remove and has low removal efficiency. However, when the removable layer 20 contains both the foaming material and the water-containing material, under the blocking effect of the substrate layer 10 and the thermosetting ink, the removable layer 20 is in a sealed state. In a sealed environment, the large amount of water molecules released by the water-containing material under high temperature can convert the external dry heating environment into an internal wet heating environment, causing the removable layer 20 to simultaneously undergo thermal-induced fracture dissociation and low-level thermal-induced swelling dissociation, thereby greatly reducing the adhesion of the removable layer 20 and making it removable.

[0117] Optionally, the water-containing material includes but is not limited to: sulfate hydrate, carbonate hydrate, water-containing chloride, water-containing silicate, water-containing organic acid salt, and water-containing phosphate.

[0118] Optionally, the sulfate hydrate includes but is not limited to: copper sulfate pentahydrate, ferrous sulfate heptahydrate, sodium sulfate decahydrate, zinc sulfate heptahydrate, magnesium sulfate heptahydrate, nickel sulfate hexahydrate, potassium aluminum sulfate dodecahydrate, cobalt sulfate heptahydrate, magnesium sulfate hexahydrate, chromium sulfate nonahydrate, calcium sulfate dihydrate, and manganese sulfate pentahydrate.

[0119] Optionally, the carbonate hydrate includes but is not limited to: magnesium carbonate pentahydrate, magnesium carbonate trihydrate, sodium carbonate decahydrate, basic copper carbonate, calcium carbonate dihydrate, cobalt carbonate hydrate, nickel carbonate hydrate, zinc carbonate hydrate, barium carbonate hydrate, strontium carbonate hydrate, lithium carbonate monohydrate, potassium carbonate monohydrate.

[0120] Optionally, the water-containing chloride includes but is not limited to: magnesium chloride hexahydrate, calcium chloride dihydrate, cobalt chloride hexahydrate, manganese chloride tetrahydrate, nickel chloride hexahydrate, copper chloride dihydrate, iron chloride hexahydrate, aluminum chloride hexahydrate, stannous chloride tetrahydrate, and strontium chloride hexahydrate.

[0121] Optionally, the water-containing silicate includes but is not limited to: water-containing silica gel, water-containing sodium silicate, water-containing zeolite, water-containing bentonite, and water-containing sepiolite.

[0122] Optionally, the water-containing organic acid salt includes, but is not limited to, sodium acetate trihydrate, sodium citrate dihydrate, ferrous ammonium sulfate heptahydrate, potassium antimonyl tartrate tetrahydrate, sodium tartrate dihydrate.

[0123] Optionally, the water-containing phosphate salt includes, but is not limited to, sodium phosphate dibasic dihydrate, potassium phosphate dibasic monohydrate, ammonium phosphate dibasic hydrate, disodium hydrogen phosphate dodecahydrate, dipotassium hydrogen phosphate trihydrate, trisodium phosphate dodecahydrate, sodium pyrophosphate decahydrate, copper pyrophosphate dihydrate, sodium hexametaphosphate hydrate, calcium hydrogen phosphate dihydrate, and sodium tripolyphosphate hexahydrate.

[0124] In a preferred embodiment, a barrier layer is provided on the side of the removable layer 20 away from the base layer, which is used to prevent the water vapor from penetrating, on the one hand, to prevent the water-containing material from deliquescing in a humid environment, and on the other hand, to prevent the water-containing material from weathering in a dry environment.

[0125] Optionally, the material used for the barrier layer of paper includes, but is not limited to, water-based gloss oil, UV gloss oil, and polymer film.

[0126] In another preferred embodiment, the specific environment is a wet heating environment, and the thermal-induced dissociation includes both thermal-induced swelling dissociation and thermal-induced rupture dissociation.

[0127] Specifically, the removable layer 20 is obtained by coating with a water-based paint containing a water-based film-forming material and a foaming material. When wet heating is applied to the removable layer 20, both thermal-induced swelling dissociation and thermal-induced rupture dissociation can be generated.

[0128] Optionally, the wet heating is water bath heating or steam heating.

[0129] Preferably, the wet heating is steam heating, which can produce the following beneficial effects:

[0130] (1) When high-temperature steam acts on the removable layer 20, condensation occurs and a large amount of heat is released, so that the temperature of the removable layer 20 reaches 120-150°C in a very short time, which is exactly in the optimal foaming temperature range of most foaming materials, and this temperature can cause the foaming material to generate extreme internal stress and make the removable layer 20 fully thermally-induced rupture dissociation. In addition, when the foaming material is foaming microspheres, the condensed water droplets can also protect the foaming microspheres from melting due to excessive temperature of the shell material. It should be noted that after the base material is finished with proofing printing, a graphic layer is provided above the removable layer 20, especially when the graphic layer is a solid color block, the graphic layer will prevent the water vapor from contacting the removable layer 20, but the thermal-induced rupture dissociation can make the rigid graphic layer generate a large number of pores together with the removable layer 20, thereby creating conditions for thermal-induced swelling dissociation.

[0131] (2) The high-temperature steam provided by the steam heating environment can enter the inside of the removable layer 20 through the pores, and the high-temperature steam can cause thermal swelling dissociation of the water-based film-forming material in the removable layer 20. The thermal swelling dissociation can break the original hydrogen bonds between the water-based film-forming material molecules and combine with water molecules to form new hydrogen bonds, thereby causing the molecular chain of the water-based film-forming material with a three-dimensional network structure to break, and the molecular weight to be greatly reduced. The removable layer 20 has a greatly reduced adhesion, rigidity and strength while maintaining the hierarchical structure. The greatly reduced adhesion, rigidity and strength of the removable layer 20 help to further improve the effect of thermal cracking dissociation. By controlling the heating time, the degree of thermal dissociation can be controlled. When the thermal swelling dissociation is moderate thermal swelling dissociation and the thermal cracking dissociation is sufficient thermal cracking dissociation, the removable layer 20 is finally disintegrated into a powder that is polymerized by low adhesion under the synergistic action of the double dissociation. The powder that is polymerized by low adhesion can be easily removed by scraping or adsorption, thereby greatly improving the removal efficiency of the removable layer 20.

[0132] It is worth noting that when the steam heating time is excessive, the liquid water produced by the condensation of water vapor continues to increase, and therefore, the removable layer can also be fully thermally swelled and dissociated. Therefore, the ideal steam heating time is 2-4 seconds.

[0133] It is pointed out that the disintegration phenomenon produced by moderate thermal swelling dissociation and sufficient thermal cracking dissociation cannot be achieved by dry heating, and cannot be achieved by other forms of wet heating. At the same time, the disintegration phenomenon is also something that the existing foaming process needs to avoid.

[0134] (3) Steam heating has fast heat conduction, short time consumption, and can greatly reduce the degree of deformation of the substrate layer 10. Comparative experiments show that, in order to cause the removable layer 20 to have moderate thermal dissociation, steam heating needs to consume 2-4 seconds, water bath heating needs to consume 3-5 seconds, pressing and heating needs to consume 6-8 seconds, and infrared heating needs to consume 30-120 seconds.

[0135] (4) The powder of the removable layer 20 obtained by steam heating has a high water content and is polymerized by low adhesion, and therefore, dust pollution of the working environment will not occur during the removal operation.

[0136] (5) Steam heating does not produce wastewater, and has good environmental protection.

[0137] In another embodiment, the specific environment includes a dry heating environment and a wet heating environment in sequence, and the thermal dissociation includes thermal cracking dissociation and thermal swelling dissociation in sequence.

[0138] Specifically, the foaming material in the removable layer 20 is first foamed by dry heating, the internal stress generated by the foaming of the foaming material can cause the removable layer 20 to have thermal-induced cracking, the thermal-induced cracking can reduce the molecular weight of the film-forming material, reduce the adhesion, and generate a large number of pores on the removable layer 20, but the removable layer 20 still maintains the integrity of the hierarchical structure. After the proofing printing is completed, the film-forming material in the removable layer 20 is subjected to thermal-induced swelling and dissociation by wet heating, thereby greatly reducing the adhesion of the removable layer 20. It is worth noting that the film-forming material undergoes chemical bond breaking during the thermal-induced cracking and dissociation, and this process is irreversible.

[0139] Preferably, the thermal-induced cracking is low-limit thermal-induced cracking, which can cause the removable layer 20 to have a large number of pores while still maintaining relatively strong adhesion, thereby preventing the removable layer 20 from producing powder drop phenomenon due to low adhesion during printing, affecting the printing quality.

[0140] Specifically, the degree of thermal-induced cracking can be controlled by controlling the temperature and time of dry heating, thereby controlling the size and number of pores.

[0141] It should be noted that the upper limit of the temperature needs to be controlled during dry heating to prevent the film-forming material in the removable layer 20 from being fully cross-linked and solidified due to high temperature.

[0142] Preferably, the dry heating is infrared or hot air heating, and the heating temperature is 70-130°C.

[0143] Further, the dry heating is infrared heating, and the heating temperature is 70-100°C.

[0144] Preferably, the wet heating is steam heating, and the thermal-induced swelling and dissociation is moderate-limit thermal-induced swelling and dissociation.

[0145] One optional application scenario of this embodiment is that in the field of ordinary offset printing, the drying method of ordinary offset ink is penetration drying and oxidation film drying, and after the removable layer 20 is subjected to low-limit thermal-induced cracking by dry heating, the removable layer 20 will generate a large number of microscopic pores, which can create conditions for the penetration drying of ordinary offset ink. After the printing process is completed, only wet heating is needed to make the removable layer 20 have moderate-limit thermal-induced swelling and dissociation, and the removable layer 20 can be easily removed.

[0146] Optionally, the thickness of the removable layer 20 is 0.001-1 mm, and the removable layer 20 with the above thickness can be realized by offset printing, intaglio printing, flexographic printing, screen printing, coating or spraying.

[0147] Preferably, the thickness of the removable layer 20 is 0.01mm-0.1mm, when the foamed microspheres are arranged in the removable layer 20, the particle size of most foamed materials is in this range, and this thickness is just enough to cover the foamed material, so that the removable layer 20 has a flat surface. In addition, by limiting the thickness of the removable layer 20, the overall thickness of the substrate is as close as possible to the thickness of the base layer 10, thereby reducing the pressure difference between the proofing and the actual printing, and further reducing the deformation of the screen dot caused by the pressure difference.

[0148] Optionally, the thickness of the removable layer 20 is greater than or equal to 0.1mm, when the specific environment is a dry heating environment, the removable layer 20 is more difficult to remove, by limiting the thickness of the removable layer 20, the stress during the removal process can be improved, thereby helping to improve the removal effect of the removable layer 20.

[0149] It should be understood that in the present application, the removable layer 20 is a kind of adherable printing ink, and finally needs to be removed from the base layer 10, so under the premise that the coating can be removed, the thinner the thickness is, the more conducive to reducing the material cost.

[0150] In another embodiment, the removable layer 20 is also provided with an adsorbing material, by adding the adsorbing material, the adsorptivity of the removable layer 20 can be increased, thereby facilitating the improvement of the permeation drying and oxidation film-forming drying effect of the ink during the proofing.

[0151] Optionally, the adsorbing material includes but is not limited to: zeolite powder, titanium dioxide powder and silicon dioxide powder.

[0152] The above substrate, the removable layer 20 contains a film-forming material, the film-forming material can be thermally dissociated in a specific environment, after the film-forming material is thermally dissociated, the adhesion is greatly reduced, and the removable layer 20 can be removed. When the above substrate is used for proofing, after the removable layer 20 is removed, the base layer 10 can be reused, thereby greatly reducing the proofing cost of the printing enterprise.

[0153] It should be noted that the degree description terms such as "low limit", "medium limit" and "sufficient" used in the specification are relative divisions based on the implementation gradient of the technical solution, and do not constitute an absolute quantitative standard, which can be divided by the following technical indexes:

[0154] (1) "Low limit" refers to the minimum necessary implementation degree to achieve the basic function of the technical solution, such as when the water-based film-forming material is low-limit thermally dissociated, the water content of the removable layer is 5%-40%(not included); when the water-based film-forming material is low-limit thermally dissociated, the volume of the foamed material in the removable layer is increased by 5%-40%(not included).

[0155] (2) "moderate" refers to a typical degree in the conventional implementation conditions in the art, such as when the water-based film-forming material is subjected to moderate thermal-induced swelling dissociation, the water content of the removable layer is 40% to 80% (not included); when the water-based film-forming material is subjected to moderate thermal-induced cracking dissociation, the volume of the foamed material in the removable layer increases by 40% to 80% (not included).

[0156] (3) "sufficient" refers to a degree that reaches or exceeds the optimal implementation effect, such as when the water-based film-forming material is subjected to sufficient thermal-induced swelling dissociation, the water content of the removable layer reaches more than 80%; when the water-based film-forming material is subjected to sufficient thermal-induced cracking dissociation, the volume of the foamed material in the removable layer increases by more than 80%.

[0157] Please refer to Figure 2 , a method for preparing a substrate of an embodiment, the method comprising the following steps:

[0158] Step S1: providing a removable layer 20 on a substrate layer 10, the film-forming material being capable of thermal-induced dissociation under a specific environment, and the removable layer 20 being removable after the film-forming material is subjected to thermal-induced dissociation.

[0159] The removable layer 20 can be provided by coating, silk printing, intaglio printing, flexographic printing, jet printing or spraying.

[0160] Optionally, the thickness of the removable layer 20 is 0.001 mm to 1 mm, and when the removable layer 20 contains foamed material, the thickness of the removable layer 20 can increase by 3 to 5 times after the foamed material is foamed. By limiting the thickness of the removable layer 20, the thickness of the removable layer 20 after the film-forming material is subjected to thermal-induced cracking dissociation can be determined, thereby ensuring that it can be stably stressed and removed.

[0161] Preferably, the thickness of the removable layer 20 is 0.01 mm to 0.1 mm, and the coating amount of the coating corresponding to the removable layer 20 with this thickness range is 3 g / m2 to 30 g / m2, which is easy to control and has a lower material cost.

[0162] In another embodiment, please refer to Figure 3 , after step S1, further comprising:

[0163] Step S2: the removable layer 20 contains foamed material, and the foamed material is subjected to thermal-induced cracking dissociation by dry heating.

[0164] After the thermally induced disintegration of the removable layer 20, a large number of micro-pores will be generated on the surface of the removable layer 20, but the removable layer 20 still maintains strong adhesion, and thus will not fall off from the base layer 10. Due to the existence of the micro-pores, the removable layer 20 has strong adsorption. Since the drying method of ordinary offset ink is penetration drying and oxidation film drying, the substrate after dry heating can be used for the proofing printing of ordinary offset printing.

[0165] It should be noted that the number of micro-pores can be controlled by controlling the temperature and time of dry heating, and thus the adsorption and adhesion of the removable layer 20 can be controlled.

[0166] The substrate prepared by the above substrate preparation method has color, thickness, gloss and flatness close to the surface of a normal substrate, and can make the dot rendering effect of proofing printing close to the dot rendering effect of actual printing.

[0167] Please refer to Figure 4 A coating removal method according to an embodiment is based on the above substrate, and the coating removal method comprises the following steps:

[0168] Step S20: causing the film-forming substance to undergo thermal disintegration in a specific environment.

[0169] When the removable layer 20 contains a water-based film-forming substance and does not contain a foaming material, the specific environment is wet heating. When the removable layer 20 does not contain a water-based film-forming substance and contains a foaming material, the specific environment is dry heating. When the removable layer 20 contains a water-based film-forming substance and contains a foaming material, the specific environment is wet heating and / or dry heating.

[0170] Step S30: removing the removable layer 20.

[0171] The removal method of the removable layer 20 includes but is not limited to scraper scraping removal, brush rubbing removal, vibration peeling, negative pressure suction or air flow blowing, etc.

[0172] Preferably, when the removable layer 20 is disintegrated into powder by low adhesion polymerization through steam heating, the removal method of the removable layer 20 can be negative pressure suction or high-speed air flow blowing, which has the characteristics of high removal efficiency and low cost.

[0173] In another embodiment, please refer to Figure 5 Before step S20, it further comprises the following step:

[0174] Step S10: setting a printed image on the removable layer 20.

[0175] The setting method of the printed image can be offset printing, intaglio printing, screen printing, flexographic printing, inkjet printing, transfer printing or hot stamping.

[0176] A security structure, comprising a substrate, a printed image layer arranged above the substrate, wherein the substrate is any of the substrates described above.

[0177] After the printed image is arranged on the substrate, the printed image layer is visible to the naked eye. When authentication is required, the heat-induced dissociation of the removable layer 20 occurs in a specific environment, and after the removable layer is removed, the security information arranged on the base layer 10 can be seen, thereby distinguishing true from false.

[0178] The following is a specific embodiment.

[0179] Embodiment 1

[0180] The first aspect of this embodiment provides a substrate, please refer to Figure 1 The substrate includes a base layer 10 and a removable layer 20 arranged in layers. The base layer 10 is a PVC sheet, and the removable layer 20 is obtained by drying the water-based varnish.

[0181] The above-mentioned substrate, the water-based film-forming material contained in the removable layer 20 can undergo heat-induced swelling dissociation in a water bath heating environment. After the water-based film-forming material undergoes heat-induced swelling dissociation, the removable layer 20 is in a colloidal state, and the adhesion is greatly reduced, so the removable layer 20 can be removed by scraping. When the above-mentioned substrate is used for proofing printing, after the removable layer 20 is removed, the base layer 10 can be reused, thereby greatly reducing the proofing cost of printing enterprises.

[0182] The second aspect of this embodiment provides a method for preparing a substrate, which is used to prepare the substrate of the first aspect of this embodiment, please refer to Figure 2 The method comprises the following steps:

[0183] Step 1: arranging a removable layer 20 on the base layer 10.

[0184] The removable layer 20 is obtained by drying the water-based varnish, and the water-based film-forming material is contained in the water-based varnish.

[0185] The substrate prepared by the embodiment contains water-based film-forming material in the removable layer 20, which can undergo heat-induced swelling dissociation in a water bath heating environment. After the water-based film-forming material undergoes heat-induced swelling dissociation, the removable layer 20 is in a colloidal state, so the removable layer 20 can be removed by scraping. When the above-mentioned substrate is used for proofing printing, after the removable layer 20 is removed, the base layer 10 can be reused, thereby greatly reducing the proofing cost of printing enterprises.

[0186] The third aspect of this embodiment provides a coating removal method, please refer to Figure 4 The method comprises the following steps:

[0187] Step 1: causing the water-based film-forming material to undergo heat-induced swelling dissociation in a water bath heating environment.

[0188] The length of heating time determines the process of thermal-induced swelling and dissociation of the water-based film-forming substance. When the water bath heating time is insufficient, the water-based film-forming substance swells into a colloid. When the water bath heating time is sufficient, the water-based film-forming substance completely dissolves in water.

[0189] Step 2: removing the removable layer 20.

[0190] When the water-based film-forming substance partially thermally swells and dissociates, the removable layer 20 is in a colloidal state, and the removable layer 20 can be removed by scraping with a scraper. When the water-based film-forming substance completely thermally swells and dissociates, the water-based film-forming substance can be directly dissolved in the water bath. After removing the removable layer 20, the base layer 10 can be reused, thereby greatly reducing the cost of proofing for printing enterprises.

[0191] The fourth aspect of the embodiment provides a security structure. The security structure comprises a substrate, and a printed image layer is arranged above the substrate, wherein the substrate is the substrate provided in the first aspect of the embodiment.

[0192] After the printed image is arranged on the substrate, the image layer can be seen by the naked eye. When authentication is required, the removable layer 20 is caused to thermally dissociate in a specific environment, and after the removable layer is removed, the security information arranged on the base layer 10 can be seen, thereby distinguishing true from false.

[0193] Embodiment 2

[0194] The first aspect of the embodiment provides a substrate, please refer to Figure 1 The substrate comprises a base layer 10 and a removable layer 20 arranged in layers. The base layer 10 is a paper sheet, and the paper sheet is provided with a PP film protective layer. The removable layer 20 comprises an oily film-forming substance and a foamed material, and the foamed material is expanded graphite.

[0195] The above-mentioned substrate, the removable layer 20 comprises the foamed material expanded graphite, and the expanded graphite is inserted with an expanding agent between the intermolecular levels. When the environmental temperature is higher than the initiation temperature of the expanding agent, the expanding agent decomposes and releases a large amount of gas. The pressure generated by the gas drives the graphite molecules between the levels to expand along the axial direction, thereby generating internal stress in the removable layer 20. The internal stress can cause the removable layer 20 to thermally dissociate and rupture. Specifically, the molecular chain of the film-forming substance is broken, the molecular weight is greatly reduced, and a large number of pores are generated in the removable layer 20, thereby expanding the volume. As a result, the adhesion between the removable layer 20 and the base layer 10 is greatly reduced, and the removable layer 20 can be removed from the base layer 10.

[0196] The second aspect of the embodiment provides a preparation method of a substrate, which is used to prepare the substrate of the first aspect of the embodiment, please refer to Figure 2 The method comprises the following steps:

[0197] First step: setting the removable layer 20 on the substrate layer 10.

[0198] Wherein, the removable layer 20 contains oily film-forming material and foaming material, and the foaming microspheres are foamed in a dry heating environment, and the internal stress generated in the foaming process can cause the thermal-induced breakage dissociation of the removable layer 20, so that the adhesion of the removable layer 20 is greatly reduced.

[0199] The third aspect of the embodiment provides a coating removal method, please refer to Figure 5 The method comprises the following steps:

[0200] First step: setting the printed graphics on the surface of the removable layer 20;

[0201] Second step: causing the thermal-induced breakage dissociation of the removable layer 20 in a dry heating environment;

[0202] Third step: removing the removable layer 20.

[0203] After the removable layer 20 is removed, the substrate layer 10 can be reused, so that the proofing cost of the printing enterprise can be greatly reduced.

[0204] Embodiment 3

[0205] The first aspect of the embodiment provides a substrate, please refer to Figure 1 The substrate comprises a substrate layer 10 and a removable layer 20 which are stacked. The substrate layer 10 is a tinplate sheet, and the removable layer 20 contains water-based film-forming material and foaming material. The water-based film-forming material is water-based acrylic resin, and the foaming material is low-temperature foaming microspheres with an initiation temperature of 80℃.

[0206] In the above-mentioned substrate, the film-forming material in the removable layer 20 is water-based acrylic resin, and the removable layer 20 contains low-temperature foaming material. When steam heating is used, the removable layer 20 can simultaneously generate sufficient thermal-induced breakage dissociation and moderate thermal-induced swelling dissociation. Under the synergistic effect of the double dissociation, the removable layer 20 is finally disintegrated into powder polymerized by low adhesion, which can be easily removed by scraping or adsorption, thereby greatly enhancing the removal efficiency of the removable layer 20.

[0207] Embodiment 4

[0208] The first aspect of the embodiment provides a substrate, please refer to Figure 1 The substrate comprises a substrate layer 10 and a removable layer 20 which are stacked. The substrate layer 10 is a tinplate sheet, and the removable layer 20 contains water-based film-forming material, foaming material and water-containing material. The water-based film-forming material is water-based polyurethane resin, the foaming material is high-temperature foaming microspheres with an initiation temperature of 160℃, and the water-containing material is magnesium carbonate pentahydrate.

[0209] The film-forming substance in the removable layer 20 is a water-based polyurethane resin, and the removable layer 20 contains a low-temperature foaming material and a water-containing material. When a thermosetting ink is provided above the removable layer 20 and dry heating at 160°C is used, on the one hand, the high temperature can cause internal stress in the foaming microspheres in the removable layer 20, and the internal stress can cause the removable layer 20 to undergo thermal cracking dissociation and generate a large number of pores; on the other hand, at high temperature, the water-containing material can generate a large number of water molecules, which can undergo low-limit thermal swelling dissociation with the film-forming substance. Under the synergistic effect of the thermal cracking dissociation and the low-limit thermal swelling dissociation, the adhesion of the removable layer 20 is greatly reduced, so that it can be removed.

[0210] Example 5

[0211] The substrate provided in this example is similar to the substrate provided in Example 3, except that the foaming material is azobisisobutyronitrile.

[0212] When the substrate is heated by dry heating, the azobisisobutyronitrile particles can decompose to generate a large amount of nitrogen gas, and the internal stress generated by the nitrogen gas can cause the removable layer 20 to undergo thermal cracking dissociation.

[0213] Example 6

[0214] The substrate provided in this example is similar to the substrate provided in Example 3, except that the foaming material is 4,4'-oxybisbenzenesulfonylhydrazide (OBSH).

[0215] When the substrate is heated by dry heating, the OBSH particles can decompose to generate a large amount of nitrogen gas and water vapor, and the internal stress generated by the nitrogen gas and water vapor can cause the removable layer 20 to undergo thermal cracking dissociation. At the same time, the water vapor generated by OBSH can cause the water-based film-forming substance to undergo thermal swelling dissociation, and the double dissociation helps to improve the removal efficiency of the removable layer 20.

[0216] The above-described examples only express several embodiments of the present application, which are described in more detail and in more detail, but cannot be construed as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application patent should be subject to the appended claims.

[0217] The above-mentioned terms should be understood in conjunction with the description of the examples, and the specific numerical range does not constitute a limitation on the scope of protection of the claims. In the infringement judgment, the technical features recorded in the claims should be used as the criterion, and the description is only used to help understand the implementation flexibility of the technical solution.

Claims

1. A substrate, characterized in that, include: The base layer is selected from any one of paper, metal sheet or composite material, wherein the composite material is paper-plastic composite material or aluminum-plastic composite material; as well as A movable layer is stacked on the base layer. The movable layer contains an aqueous film-forming substance and a foaming material. The aqueous film-forming substance undergoes moderate thermal swelling dissociation and full thermal rupture dissociation under a steam heating environment. Under the synergistic effect of the dual dissociation, the movable layer disintegrates into a powder polymerized by low binding force, which can be removed from the movable layer. When the aqueous film-forming substance undergoes moderate thermal swelling and dissociation, the water content of the movable layer is greater than or equal to 40% and less than 80%; when the aqueous film-forming substance undergoes full thermal rupture and dissociation, the volume of the foaming material in the movable layer increases by more than 80%; the aqueous film-forming substance is selected from at least one of polyurethane resin, acrylic resin, polyvinyl alcohol and its modified resin, polyethylene oxide resin, starch and its derivatives, and polyvinylpyrrolidone; the foaming material is selected from at least one of physical foaming materials, chemical foaming materials, and inorganic foaming materials; the physical foaming material is selected from any one of foamed microspheres, expanded graphite, vermiculite powder, and expanded hexagonal boron nitride; the chemical foaming material is selected from any one of azo foaming materials, carbonate foaming materials, and hydrazine foaming materials; the inorganic foaming material is selected from any one of metal hydride foaming materials and silicate foaming materials.

2. The substrate according to claim 1, characterized in that, The steam heating time is 2-4 seconds.

3. The substrate according to claim 1, characterized in that, The initiation temperature of the foaming material is 60℃-200℃.

4. The substrate according to claim 1, characterized in that, The thickness of the movable layer is 0.001mm-1mm.

5. The substrate according to claim 1, characterized in that, The base layer is quadrilateral, pentagonal, or hexagonal.

6. A method for preparing a substrate, wherein the substrate is the substrate according to any one of claims 1-5, characterized in that, include: Step S1: Set a movable layer on the base layer; The removable layer comprises an aqueous film-forming substance and a foaming material. The aqueous film-forming substance undergoes moderate thermal swelling dissociation and full thermal rupture dissociation under a steam heating environment. Under the synergistic effect of the dual dissociation, the removable layer disintegrates into a powder polymerized by low binding force, which can be removed from the removable layer.

7. A coating removal method, implemented on a substrate as described in any one of claims 1-5, characterized in that, Includes the following steps: The aqueous film-forming material is subjected to moderately limited thermal swelling and dissociation and fully thermal rupture dissociation under a steam heating environment. Under the synergistic effect of the dual dissociation, the mobile layer disintegrates into powder that is polymerized by low binding force. Remove the movable layer.

8. The coating removal method according to claim 7, characterized in that, The removal method can be selected from any one of the following: scraping removal with a scraper, brush removal, vibration peeling, negative pressure suction removal, or airflow blowing removal.

9. An anti-counterfeiting structure, characterized in that, The substrate includes a printed graphic layer disposed on the substrate, wherein the substrate is the substrate according to any one of claims 1-5.

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