A method for sticking a film on a color box

Abstract

The present application relates to the technical field of carton processing, and particularly relates to a laminated color carton sticking box method, which comprises the following steps: applying water-based adhesive to the sticking part of the laminated color carton and making the sticking sheet overlap the sticking area; pre-pressing the sticking part by the first pressing member arranged at intervals at a first pressing pressure and keeping pressing; keeping the first pressing member pressing, pressing the sticking part by the second pressing member arranged between adjacent first pressing members at a second pressing pressure greater than the first pressing pressure; keeping the first pressing member and the second pressing member pressing together to complete the sticking box forming of the laminated color carton; and solidifying and shaping the laminated color carton after the sticking box forming. The problems of insufficient sticking effect of the adhesive on the laminated surface, easy position deviation of the sticking sheet, uneven pressing and sticking of the sticking area, and insufficient sticking stability after solidification in the process of sticking the box of the laminated color carton are solved.

Description

Technical Field

[0001] This invention relates to the field of cardboard box processing technology, and in particular to a method for gluing laminated color boxes. Background Technology

[0002] Laminated color boxes are packaging products formed by covering the surface of a printed paper box with a plastic film. They feature high surface gloss, wear resistance, water resistance, and good appearance, and are widely used in the packaging of electronic products, food, gifts, and other products. The laminating materials used in current laminated color boxes typically include BOPP film, etc. After the film is applied to the surface of the paper substrate, a relatively dense lamination layer is formed on the surface of the color box.

[0003] During the gluing process of laminated carton, adhesive needs to be applied between the adhesive sheet and the corresponding bonding area, and the adhesive sheet is fixed to the bonding area by pressing. However, compared with the uncoated paper surface, the laminated surface places higher demands on the wetting and adhesion performance of the adhesive. Ordinary adhesives are prone to insufficient spreading and inadequate interfacial bonding on the laminated surface. Especially after changes in ambient temperature and humidity, problems such as delamination and separation of the adhesive can easily occur at the bonding points, affecting the structural stability of the carton after molding.

[0004] Meanwhile, existing gluing and pressing methods often struggle to simultaneously ensure both the positioning stability of the adhesive sheet and the full adhesion of the bonding interface. When significant pressure is applied immediately after the adhesive sheet and bonding area have just overlapped, the adhesive sheet is prone to lateral slippage or positional displacement during pressing because the adhesive is still in a fluid state. Furthermore, the adhesive may concentrate and spread in localized pressure areas or even be squeezed outwards from the bonding area. Conversely, insufficient pressing pressure can lead to incomplete adhesion in some areas, uneven adhesive layer thickness, or gaps at the interface, thus affecting the consistency of the bond. Therefore, how to further improve the adhesion of the entire bonding area while maintaining the relative stability of the adhesive sheet is a problem that needs to be solved in the gluing process of laminated carton.

[0005] Furthermore, during the processing, transportation, and gluing of laminated cartons, dust, paper scraps, and other impurities easily adhere to the bonding areas and adjacent regions. When these impurities remain at the bonding interface, they occupy the effective contact area between the adhesive and the laminated surface, affecting the continuity of the bonding interface. When impurities are trapped between the laminated cartons and the processing components, they may also rub against the laminated surface during transportation and pressing, causing scratches on the laminated surface and thus affecting the appearance quality of the product.

[0006] Furthermore, the adhesive used for gluing laminated cartons requires a certain curing time to form a stable bond. If the temperature, humidity, or curing time during the curing process is unsuitable, the adhesive may not cure sufficiently, causing the bonded areas to separate during subsequent stacking, transportation, or use. Therefore, it is necessary to provide a method for gluing laminated cartons to improve the adhesive performance of the laminated surface, enhance the positional stability of the adhesive sheet during the pressing process, improve the uniformity of the bonding area, and increase the overall bonding stability after gluing.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] This invention provides a method for gluing laminated color boxes to solve the problems of insufficient adhesion of adhesives on the laminated surface, easy displacement of adhesive sheets during pressing, uneven pressure and bonding in the bonding area, and insufficient bonding stability after curing in existing laminated color box gluing processes.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for gluing laminated color boxes, the method comprising: Apply water-based adhesive to the bonding area of ​​the laminated carton and overlap the adhesive sheet with the bonding area; The bonding area is pre-pressed and maintained by a first pressing pressure using a first pressing member that is spaced apart; While the first pressing member remains pressed, the adhesive portion is pressed together by a second pressing member disposed between adjacent first pressing members with a second pressing pressure greater than the first pressing pressure. The first and second pressing components are pressed together to complete the gluing and forming of the laminated color box; The laminated color box after gluing and molding is cured and shaped.

[0010] More specifically, after applying a water-based adhesive to the bonding areas of the laminated carton, the adhesive sheet is overlapped with the corresponding bonding area according to the predetermined bonding position, so that the water-based adhesive is located between the adhesive sheet and the bonding area, thereby forming a bonding interface to be pressed. The water-based adhesive can spread along the bonding interface under the subsequent pressing action, establishing an adhesive bond between the adhesive sheet and the bonding area, and providing an adhesive foundation for the subsequent two-stage pressing.

[0011] More specifically, the first pressing members are spaced apart along the bonding area. After the adhesive sheet and the bonding area are overlapped, multiple first pressing members apply a small initial pressing pressure to multiple spaced positions of the bonding area. By applying multi-point pre-pressing to the bonding area, the adhesive sheet and the bonding area are initially bonded at several locations, thereby constraining the position of the adhesive sheet. Compared with applying a large pressure directly to the entire bonding area, the pre-pressing process can reduce the possibility of lateral slippage of the adhesive sheet while avoiding excessive compression of the water-based adhesive.

[0012] After the first pressing component completes its pre-pressing, it continues to maintain the pressed state, ensuring that the multiple pre-pressing positioning points that have been established continuously constrain the adhesive sheet during the subsequent operation of the second pressing component. Therefore, even before the water-based adhesive has fully cured, the first pressing component can provide mechanical positioning, preventing the adhesive sheet from shifting as a whole when the second pressing component applies greater pressure, thus improving the consistency of the adhesive sheet's position.

[0013] More specifically, the second pressing member is disposed between adjacent first pressing members, and applies a second pressing pressure greater than the first pressing pressure to the adhesive area while the first pressing members are kept pressed. The second pressing member mainly further presses the areas between the first pressing members that have not been fully pressed, so that the adhesive sheet in the corresponding area is close enough to the adhesive area, and promotes the further spreading of the water-based adhesive at the adhesive interface, thereby reducing the local difference in adhesive layer thickness and the gaps in the adhesive interface.

[0014] The first pressing member and the second pressing member are arranged in an alternating spatial configuration. On the one hand, the first pressing member can continuously play a positioning role during the operation of the second pressing member. On the other hand, the second pressing member can act on the interval area between the first pressing members, so that the action areas of the two types of pressing members complement each other and reduce the insufficiently compressed areas caused by the spacing of a single pressing member.

[0015] More specifically, once the second pressing component reaches the predetermined pressing state, the first and second pressing components are simultaneously pressed together. Through the combined action of these two types of pressing components, the pre-pressed area formed by the first pressing component and the main pressing area formed by the second pressing component together constitute a continuous or substantially continuous pressure area. This ensures the overall bonding of the adhesive area remains stable and adhered, facilitating the formation of a relatively uniform adhesive layer at the bonding interface and increasing the effective contact area between the water-based adhesive and the adhesive sheet and bonding area.

[0016] More specifically, after the above pressing is completed, the laminated color box after gluing and molding is cured and shaped, so that the film-forming component in the water-based adhesive and the resin component with adhesive effect further form a stable adhesive layer, thereby fixing the relative position between the adhesive sheet and the adhesive area, reducing the possibility of the adhesive part rebounding or subsequent delamination after the pressing is released.

[0017] Furthermore, the bonding areas of the laminated carton are air-cleaned before applying the water-based adhesive.

[0018] More specifically, by applying a clean airflow to the bonding area of ​​the laminated carton, dust, paper scraps, and other impurities adhering to the bonding surface are removed. This reduces localized isolation caused by impurities trapped between the water-based adhesive and the laminated surface, allowing the adhesive to maintain more continuous contact with the bonding area. Furthermore, it reduces friction between hard particles and the laminated surface during transport and pressing, lowering the likelihood of scratches and thus balancing bonding quality with the carton's appearance.

[0019] Furthermore, the waterborne adhesives include high glass transition temperature styrene-acrylic non-film-forming emulsions, solid acrylic alkali-soluble resins, waterborne leveling agents, ethanol, waterborne wetting agents, waterborne defoamers, waterborne abrasion resistant agents, waterborne slip agents, pure acrylic emulsions, and water.

[0020] More specifically, high glass transition temperature styrene-acrylic non-film-forming emulsions are mainly used to improve the initial tack and cohesive strength of the adhesive layer; solid acrylic alkali-soluble resins are used to improve the adhesive strength and heat resistance of the adhesive layer; pure acrylic emulsions have good film-forming ability and can form a synergy with high glass transition temperature styrene-acrylic non-film-forming emulsions, so that the resulting adhesive layer has both film-forming properties and cohesive strength, thereby improving the problem of insufficient film-forming performance when using high glass transition temperature emulsions alone.

[0021] Water-based leveling agents improve the spreading and leveling properties of water-based adhesives on bonding surfaces, resulting in a more uniform adhesive layer distribution after application. Water-based wetting agents improve the wetting properties of water-based adhesives on the coating surface, increasing the contact between the adhesive and the coating surface. Water-based defoamers suppress air bubbles generated during adhesive formulation and application, reducing localized bonding defects caused by residual bubbles. Water-based abrasion-resistant agents improve the abrasion resistance of the bonded areas. Water-based slip agents improve the processing properties of water-based adhesives. Ethanol regulates the drying process of the system and facilitates defoaming. Water serves as the solvent and diluent in the system. Through the combination of these components, the water-based adhesive simultaneously achieves good wetting and spreading properties on the coating surface, film-forming properties, and cohesive strength of the adhesive layer.

[0022] Furthermore, the preparation methods of high glass transition temperature styrene-acrylic non-film-forming emulsions, by mass parts, include: A mixture of 40-60 parts styrene, 10-20 parts butyl acrylate and 15-25 parts methyl methacrylate is used as the monomer phase. A mixture of 80-120 parts deionized water, 1-3 parts anionic emulsifier and 0.5-2 parts nonionic emulsifier is used as the aqueous phase. The monomer phase and the aqueous phase are then mixed to form a pre-emulsion. The preemulsion is divided into a first preemulsion and a second preemulsion, and the ammonium persulfate initiator, with a total dosage of 0.3 to 0.8 parts, is divided into a first initiator and a second initiator. The first preemulsion and the first initiator are added to the reaction system, and the temperature is raised to 75~85℃ to initiate polymerization to form a seed emulsion. Then, the second preemulsion and the second initiator are added dropwise, and the dropwise addition time is controlled to be 2~4h and the reaction temperature is 80±5℃. After the addition is complete, keep warm for 1-2 hours, cool down to below 40℃, adjust the pH to 7.5-8.5 with ammonia water, and filter to obtain a high glass transition temperature styrene-acrylic non-film-forming emulsion.

[0023] More specifically, by first polymerizing the first pre-emulsion under the action of the first initiator to form a seed emulsion, a foundation for latex particle growth can be established in the reaction system beforehand. Then, the second pre-emulsion and the second initiator are added dropwise, allowing subsequent monomers to continuously polymerize around the existing latex particles. This facilitates control of the polymerization process and avoids fluctuations caused by the concentrated addition of large amounts of monomers. Controlling the dropwise addition time to 2–4 hours and the reaction temperature to 80±5℃ ensures a relatively stable polymerization process. After the dropwise addition is completed, maintaining the temperature for another 1–2 hours allows the remaining monomers to further polymerize.

[0024] After polymerization, the system is cooled to below 40°C, and the pH is adjusted to 7.5–8.5 using ammonia water to maintain the resulting emulsion in a suitable state for storage and compounding. The high glass transition temperature styrene-acrylic non-film-forming emulsion prepared by the above method is mainly used to provide high cohesive strength. It does not primarily function as a standalone film-forming agent on the coating surface, but rather forms an adhesive layer with pure acrylic emulsion to balance the strength of the adhesive layer and continuous film-forming performance.

[0025] Furthermore, the preparation method of solid alkali-soluble acrylic resin, by mass parts, includes: Mix 25-35 parts of acrylic acid, 10-20 parts of methacrylic acid, 30-50 parts of styrene and 40-60 parts of isopropanol, and heat to 85-95°C under nitrogen protection; A solution of isopropanol containing 1-3 parts of benzoyl peroxide was added dropwise, and the mixture was refluxed for 3-5 hours until the acid value reached 80-120 mg KOH / g. The mixture was then cooled to below 60°C, and the reaction solution was added dropwise to deionized water to precipitate the product. After centrifugation, washing, vacuum drying, and pulverization, a solid alkali-soluble acrylic resin was obtained.

[0026] More specifically, acrylic acid and methacrylic acid provide acidic groups to the resulting resin, enabling it to form a soluble or dispersible state in an alkaline aqueous system; the styrene structural units help improve the cohesive strength and heat resistance of the resin after forming the adhesive layer. Isopropanol serves as the polymerization reaction medium, allowing the monomers to polymerize in a relatively homogeneous reaction system; the use of benzoyl peroxide as an initiator, added dropwise, helps control the free radical polymerization process.

[0027] The reaction was controlled until the acid value reached 80–120 mg KOH / g, ensuring that the resulting resin retained acidic groups capable of responding to pH changes in the system. The resulting solid acrylic alkali-soluble resin was soluble in alkaline aqueous solutions. During the drying process of the water-based adhesive, as the volatile alkaline components and moisture gradually decreased, the system state changed, allowing the resin to gradually participate in the formation of a more stable adhesive layer. This, in turn, improved the adhesive strength and heat resistance of the water-based adhesive after curing.

[0028] Furthermore, the preparation method of the water-based adhesive, by weight parts, includes: Add 8-15 parts of solid alkali-soluble acrylic resin to 20-30 parts of deionized water, stir and dissolve at 60-70℃, and adjust the pH to 8.0-9.0 with ammonia water to obtain a resin solution; 25-35 parts of a high glass transition temperature styrene-acrylic non-film-forming emulsion were mixed with 15-25 parts of a pure acrylic emulsion to obtain a mixed emulsion; The resin solution is added to the mixed emulsion and mixed, and then 0.3-0.8 parts of water-based leveling agent, 0.5-1.5 parts of water-based wetting agent, 0.2-0.5 parts of water-based defoamer, 1-3 parts of water-based abrasion-resistant agent and 0.5-1.5 parts of water-based slip agent are added in sequence. Then 3-8 parts of ethanol are added, mixed and filtered to obtain water-based adhesive.

[0029] More specifically, the solid alkali-soluble acrylic resin is first added to deionized water at 60-70°C, and the pH of the system is adjusted to 8.0-9.0 with ammonia water so that the solid alkali-soluble acrylic resin can be fully dissolved and form a uniform resin solution, thereby avoiding local agglomeration or uneven dispersion when the solid resin is directly mixed with the emulsion.

[0030] A high glass transition temperature styrene-acrylic non-film-forming emulsion is premixed with a pure acrylic emulsion to fully disperse the emulsion component with high cohesive strength and the emulsion component with film-forming effect, thereby forming a synergistic adhesive layer during the subsequent drying and curing process. Then, a resin solution is added to the mixed emulsion to uniformly distribute the alkali-soluble acrylic resin in the emulsion system, so as to jointly constitute the main adhesive system of the water-based adhesive.

[0031] After the main system is formed, water-based leveling agents, water-based wetting agents, water-based defoamers, water-based abrasion-resistant agents, and water-based slip agents are added sequentially. This ensures that each functional additive is fully dispersed in the system, avoiding excessively high local concentrations or uneven dispersion caused by adding them all at once. Ethanol is then added to regulate the defoaming and drying process. Finally, filtration removes any gel particles and other impurities that may have formed during the preparation process, resulting in a relatively uniform and stable water-based adhesive suitable for application to the bonding areas of laminated color boxes.

[0032] Furthermore, the first pressing pressure is 0.2~0.4MPa.

[0033] More specifically, the first pressing pressure is set to 0.2–0.4 MPa, enabling the first pressing component to exert a pre-pressure on the adhesive sheet sufficient to restrict its relative movement. This allows the adhesive sheet and the bonding area to form initial adhesion at multiple intervals, while avoiding concentrated compression of the adhesive with high pressure in the first stage. Thus, the first pressing stage primarily serves a pre-positioning function, providing a stable adhesive position basis for the subsequent application of higher pressure pressing by the second pressing component.

[0034] Furthermore, the second pressing pressure is 0.6~0.8MPa.

[0035] More specifically, the second pressing pressure is greater than the first pressing pressure. While the first pressing member remains positioned, the second pressing member applies a pressure of 0.6–0.8 MPa to the area between adjacent first pressing members, further compressing this area. This allows the water-based adhesive to spread fully at the bonding interface and improves the adhesion between the adhesive sheet and the bonding area. The graded pressure control achieved through the first and second pressing pressures separates the pre-positioning function from the main pressing function, which is beneficial for balancing the stability of the adhesive position and the full adhesion of the bonding interface.

[0036] Furthermore, the curing and shaping were carried out at a temperature of 25±5℃ and a relative humidity of 60±10%.

[0037] By controlling the curing environment within the range of temperature 25±5℃ and relative humidity 60±10%, a relatively stable environmental condition is provided for the gradual release of moisture and other volatile components in the water-based adhesive and the formation of a stable adhesive layer. This reduces the differences in drying speed caused by excessive fluctuations in ambient temperature or humidity, and keeps the adhesive parts in a relatively stable curing process, thereby improving the consistency of the gluing quality between different laminated boxes.

[0038] Furthermore, the curing and setting time shall not be less than 24 hours.

[0039] More specifically, the laminated carton should be allowed to cure for at least 24 hours after pressing, so that the water-based adhesive has enough time to dry, form a film, and stabilize the adhesive layer. This will allow a stable adhesive structure to be formed between the adhesive sheet and the bonding area, thereby reducing the problem of the adhesive parts separating when the product enters the stacking, packaging, or transportation process too early because the adhesive has not been fully cured.

[0040] The technical solution of this invention can achieve the following technical effects: 1. The present invention adopts a two-stage pressing method, which involves pre-pressing and positioning with the first pressing component, maintaining pressing with the first pressing component, and pressing with the second pressing component under greater pressure. In the second pressing stage, the first pressing component is still used to constrain the position of the adhesive sheet, which can reduce the possibility of lateral slippage and adhesive position deviation of the adhesive sheet under greater pressure. 2. The present invention arranges the first pressing component and the second pressing component alternately, and the two together maintain the pressing, so that the pre-pressing area and the main pressing area complement each other, which can improve the overall adhesion of the bonding area and facilitate the uniform spread of water-based adhesive and the formation of a more uniform adhesive layer. 3. The present invention uses an aqueous adhesive comprising components such as a high glass transition temperature styrene-acrylic non-film-forming emulsion, a solid acrylic alkali-soluble resin, and a pure acrylic emulsion. Through the synergy of the high glass transition temperature emulsion and the pure acrylic emulsion, and the coordination of the acrylic alkali-soluble resin, the adhesive possesses wetting and spreading properties on the film surface, film-forming properties, and cohesive strength of the adhesive layer, which is beneficial to improving the bonding stability of the film-coated color box. 4. Before applying the water-based adhesive, the present invention can clean the bonding area with airflow, which can reduce the impact of dust, paper scraps and other impurities on the bonding interface and reduce the possibility of impurities scratching the coating surface during processing. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart illustrating the process of gluing laminated color boxes. Figure 2 This is a schematic diagram showing the relative positions of the first pressing member and the second pressing member; Reference numerals: 1. First pressing member; 2. Second pressing member. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] The above description is merely an overview of the technical solution of this application. In order to make the technical means of this application clearer and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below.

[0046] Example 1:

[0047] This embodiment provides a method for preparing a high glass transition temperature styrene-acrylic non-film-forming emulsion, the specific steps of which are as follows: Weigh out 50 parts of styrene, 15 parts of butyl acrylate and 20 parts of methyl methacrylate by mass, mix the above raw materials evenly to obtain the monomer phase.

[0048] Weigh 100 parts of deionized water, 2 parts of anionic emulsifier, and 1 part of nonionic emulsifier, and mix the above raw materials evenly to obtain the aqueous phase.

[0049] The monomer phase is mixed with the aqueous phase and emulsified to obtain a pre-emulsion.

[0050] The preemulsion is divided into a first preemulsion and a second preemulsion, with the first preemulsion accounting for 30% and 70% of the total preemulsion mass, respectively.

[0051] Weigh 0.5 parts of ammonium persulfate as an initiator, and divide it into a first initiator and a second initiator according to 30% and 70% of the total mass of ammonium persulfate, respectively. The first initiator accounts for 30% of the total mass of ammonium persulfate, i.e., 0.15 parts; the second initiator accounts for 70% of the total mass of ammonium persulfate, i.e., 0.35 parts.

[0052] A first preemulsion and a first initiator are added to the reactor, and the reaction system is heated to 80°C to initiate the polymerization of the monomers in the first preemulsion to form a seed emulsion.

[0053] Keep the reaction system in a polymerization state, and gradually add the second preemulsion and the second initiator dropwise into the reactor. The dropwise addition time is controlled to be 3 hours, and the reaction temperature is maintained at 80±5℃ during the dropwise addition process.

[0054] After the addition is complete, the reaction is kept at the above-mentioned temperature for another 1.5 hours to allow the remaining monomers to further polymerize. Then the reaction system is cooled down, and when the temperature drops below 40°C, ammonia is added to adjust the pH of the system to 8.0.

[0055] After adjustment, the material is filtered out to obtain a high glass transition temperature styrene-acrylic non-film-forming emulsion.

[0056] The glass transition temperature of the obtained high glass transition temperature styrene-acrylic non-film-forming emulsion was controlled at 45–65℃, the solid content was controlled at 45±2%, and the latex particle size was controlled at 80–150 nm.

[0057] High glass transition temperature styrene-acrylic non-film-forming emulsions do not primarily function to form films independently on the coating surface. Instead, they are used in conjunction with pure acrylic emulsions in subsequent aqueous adhesive systems. The high glass transition temperature styrene-acrylic emulsions enhance the cohesive strength of the adhesive layer, while the pure acrylic emulsions improve the continuous film-forming properties, resulting in an adhesive layer that combines film-forming performance with structural strength.

[0058] Example 2:

[0059] This embodiment provides a method for preparing solid alkali-soluble acrylic resin, the specific steps of which are as follows: Weigh out 30 parts of acrylic acid, 15 parts of methacrylic acid, and 40 parts of styrene by mass, and add the monomers to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser.

[0060] Add 50 parts of isopropanol to a four-necked flask as a reaction solvent, and continuously purge the reaction system with nitrogen gas for 15 minutes to reduce the influence of oxygen on the free radical polymerization reaction.

[0061] After nitrogen protection is completed, the reaction system is heated to 90°C.

[0062] Weigh out 2 parts of benzoyl peroxide and dissolve it in isopropanol to form an initiator solution. Then, gradually add the obtained initiator solution dropwise to the reaction system, controlling the dropping rate to keep the reaction system stable.

[0063] After the initiator is added, the reaction system is kept at 85-95℃ for reflux reaction and the reaction is continued for 4 hours until the acid value of the reaction system is in the range of 80-120 mgKOH / g.

[0064] After the reaction is complete, the reaction solution is cooled to below 60°C, and while stirring, the reaction solution is slowly dripped into deionized water to precipitate the acrylic resin formed by polymerization.

[0065] The precipitated resin was centrifuged and washed sequentially, and then vacuum dried at 60°C. After drying, it was pulverized to obtain a white solid alkali-soluble acrylic resin.

[0066] The resulting solid acrylic alkali-soluble resin has alkali-soluble properties and can form a dissolved state in an alkaline water system with a pH of not less than 8. This allows for the pre-formation of a uniform resin solution during the subsequent preparation of water-based adhesives, reducing the possibility of agglomeration caused by directly adding solid resin.

[0067] Example 3:

[0068] This embodiment provides a method for preparing an aqueous adhesive, the specific steps of which are as follows: This embodiment uses the high glass transition temperature styrene-acrylic non-film-forming emulsion obtained in Example 1 and the solid acrylic alkali-soluble resin obtained in Example 2 to prepare an aqueous adhesive.

[0069] The following dosages are used for each component based on parts by mass: The composition includes 11.5 parts of solid acrylic alkali-soluble resin, 28.1 parts of deionized water, 30 parts of high glass transition temperature styrene-acrylic non-film-forming emulsion, 20 parts of pure acrylic emulsion, 0.55 parts of water-based leveling agent (polyether-modified polysiloxane leveling agent), 1 part of water-based wetting agent (acetylenol-based nonionic wetting agent), 0.35 parts of water-based defoamer (polyether-modified organosilicon defoamer), 2 parts of water-based abrasion-resistant agent (polyethylene wax emulsion), 1 part of water-based slip agent (polyether-modified polysiloxane-based water-based slip agent), and 5.5 parts of ethanol.

[0070] First, 11.5 parts of solid alkali-soluble acrylic resin were added to 28.1 parts of deionized water and stirred in a 65°C water bath. At the same time, ammonia was used to adjust the pH of the system to 8.5 to fully dissolve the solid alkali-soluble acrylic resin and obtain a uniform and transparent resin solution.

[0071] Subsequently, 30 parts of high glass transition temperature styrene-acrylic non-film-forming emulsion were mixed with 20 parts of pure acrylic emulsion, and stirred at low speed of 400 rpm for 18 minutes at room temperature to ensure thorough mixing of the two emulsions, thus obtaining a mixed emulsion.

[0072] The aforementioned resin solution was slowly added to the mixed emulsion, and the mixture was stirred at 500 rpm for 25 minutes to ensure that the solid alkali-soluble acrylic resin was evenly distributed in the emulsion system.

[0073] Subsequently, 0.55 parts of water-based leveling agent, 1 part of water-based wetting agent, 0.35 parts of water-based defoamer, 2 parts of water-based abrasion-resistant agent, and 1 part of water-based slip agent were added to the system in sequence.

[0074] After each additive is added, the mixture is stirred at 700 rpm for 8 minutes to ensure that the additive is fully dispersed before adding the next additive. This reduces the possibility of uneven concentration or insufficient dispersion caused by adding different additives at the same time.

[0075] After the above-mentioned additives are added, 5.5 parts of ethanol are added, and the mixture is stirred at 350 rpm for 10 minutes to adjust the defoaming state of the system and its subsequent drying performance.

[0076] After stirring, the resulting mixture is filtered through a 200-mesh filter to remove gel particles and other solid impurities that may be generated during the preparation process, thus obtaining an aqueous adhesive.

[0077] The resulting water-based adhesive has a pH controlled at 7.5–8.5, a solid content controlled at 40–50%, and a viscosity controlled at 25–40 s using a Forecast cup. It can be used for spraying or roller coating of the bonding parts of laminated color boxes.

[0078] Example 4:

[0079] This embodiment provides a method for gluing laminated color boxes, the specific steps of which are as follows: S1, Airflow Cleaning The laminated boxes to be glued are transported to the gluing station, and the gluing areas of the laminated boxes are cleaned with airflow before the water-based adhesive is applied.

[0080] Airflow cleaning is performed using multiple evenly distributed air columns, with the outlets of the multiple air columns facing the bonding area of ​​the laminated color box, so that the cleaning airflow is evenly applied to the surface of the bonding area through the multiple air columns.

[0081] Multiple evenly distributed air columns are used to impact the bonding area with airflow at multiple points, removing dust, paper scraps and other impurities adhering to the surface of the bonding area. This reduces the impact of impurities on the subsequent contact between the water-based adhesive and the coating surface, and also reduces the possibility of scratches caused by impurities rubbing against the coating surface during subsequent conveying and pressing.

[0082] After the airflow cleaning is completed, there is no visible dust or impurities on the adhesive surface of the laminated color box.

[0083] S2, Apply water-based adhesive The water-based adhesive obtained in Example 3 was uniformly applied to the bonding area of ​​the laminated carton using a roller coating method.

[0084] After the adhesive is applied, the adhesive sheet of the laminated color box is overlapped with the corresponding bonding area according to the predetermined bonding position, so that the water-based adhesive is located between the adhesive sheet and the bonding area.

[0085] By combining water-based leveling agents and water-based wetting agents, water-based adhesives can spread on the film surface and form a continuous bonding interface under subsequent pressing.

[0086] S3, First-stage pre-compression positioning Reference Figure 2 The color box is located directly below the first pressing member 1 and the second pressing member 2. After the adhesive sheet overlaps with the bonding area, the multiple spaced first pressing members 1 move toward the bonding area.

[0087] The first pressing member 1 is controlled to apply a first pressing pressure of 0.3 MPa to multiple spaced positions of the bonding area.

[0088] Under the first pressing pressure, the adhesive sheet and the bonding area are initially bonded at multiple locations, and the adhesive sheet is pre-positioned.

[0089] After the first pressing member 1 reaches the predetermined pressing position, it does not immediately lift up, but continues to remain in the pressing state, thereby constraining the position of the adhesive sheet while the water-based adhesive still has fluidity.

[0090] S4, Second Stage Main Pressing While the first pressing member 1 remains in a pressed state, the second pressing member 2, which is disposed between adjacent first pressing members, moves toward the bonding area.

[0091] The second pressing member 2 is controlled to apply a second pressing pressure of 0.7 MPa to the area between adjacent first pressing members.

[0092] Because the second pressing pressure is greater than the first pressing pressure, the second pressing component can further press the areas that were not fully pressed in the first stage, bringing the adhesive sheet and the bonding area closer together and promoting the spread of the water-based adhesive along the bonding interface.

[0093] Meanwhile, since the first pressing member 1 remains in a pressed state, it can continuously restrict the overall lateral movement of the adhesive sheet, thereby reducing the possibility of misalignment of the adhesive sheet during the application of greater pressure by the second pressing member 2.

[0094] S5, Combined Pressure Holding After the second pressing member 2 reaches the predetermined position, the first pressing member 1 and the second pressing member 2 are kept in a pressing state at the same time.

[0095] The first pressing member 1 and the second pressing member 2 are staggered along the bonding area, so that the pre-pressing area corresponding to the first pressing member 1 and the main pressing area corresponding to the second pressing member 2 complement each other, thereby forming a continuous or substantially continuous pressure area at the bonding part.

[0096] Combined pressing can further reduce the local gaps at the bonding interface and allow the water-based adhesive to form a relatively uniform adhesive layer between the adhesive sheet and the bonding area.

[0097] After the joint pressing is completed, the pressing effect of the second pressing component 2 and the first pressing component 1 on the laminated color box is released, and the laminated color box after gluing and molding is obtained.

[0098] S6, Curing and Shaping After the box is glued and formed, the laminated color box is transferred to an environment with a temperature of 25℃ and a relative humidity of 60% for curing and shaping. The curing time is 24 hours.

[0099] During the curing process, the water and ethanol in the water-based adhesive gradually evaporate, and the pure acrylic emulsion gradually forms a continuous film. The high glass transition temperature styrene-acrylic non-film-forming emulsion works with the film to improve the cohesive strength of the adhesive layer. At the same time, the solid acrylic alkali-soluble resin participates in the formation of a stable adhesive structure.

[0100] After curing, the laminated color box with adhesive bonding is obtained.

[0101] Example 5:

[0102] This embodiment is basically the same as embodiment 4, except that: The first pressing pressure of the first pressing component 1 is set to 0.2 MPa, and the second pressing pressure of the second pressing component 2 is set to 0.6 MPa; After the box is glued and formed, the laminated color box is cured and shaped in an environment with a temperature of 20℃ and a relative humidity of 50% for no less than 24 hours.

[0103] The remaining steps of airflow cleaning, application of water-based adhesive, first pressing member 1 maintaining pre-pressure, second pressing member 2 main pressing, and combined pressure holding are the same as in Example 4.

[0104] Example 6:

[0105] This embodiment is basically the same as embodiment 4, except that: The first pressing pressure of the first pressing component 1 is set to 0.4 MPa, and the second pressing pressure of the second pressing component 2 is set to 0.8 MPa; After the box is glued and formed, the laminated color box is cured and shaped in an environment with a temperature of 30℃ and a relative humidity of 70% for no less than 24 hours.

[0106] The remaining steps are the same as in Example 4.

[0107] Examples 4-6 specify the intermediate and boundary values ​​of the first pressing pressure, the second pressing pressure, and the curing environment, respectively. The first pressing component 1 first undertakes the pre-pressing and positioning function of the adhesive sheet. While the first pressing component maintains the pressing, the second pressing component 2 applies a larger main pressing pressure to the area between the first pressing components 1. Finally, the two types of pressing components work together to maintain the pressing, so that the adhesive area obtains a relatively continuous pressing state and forms a stable adhesive structure in the subsequent curing process.

[0108] Although this application has been described in conjunction with specific features and embodiments, it is apparent that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and accompanying drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for gluing laminated color boxes, characterized in that, The method includes: Apply water-based adhesive to the bonding area of ​​the laminated carton and overlap the adhesive sheet with the bonding area; The bonding portion is pre-pressed and held in place by a first pressing pressure applied by a first pressing member that is spaced apart; While the first pressing member remains pressed, the adhesive portion is pressed together by a second pressing member disposed between adjacent first pressing members with a second pressing pressure greater than the first pressing pressure. The first pressing component and the second pressing component are pressed together to complete the gluing and forming of the laminated color box; The laminated color box after gluing and molding is cured and shaped.

2. The method for gluing laminated color boxes according to claim 1, characterized in that, Before applying the water-based adhesive, the bonding area of ​​the laminated carton is cleaned with airflow.

3. The method for gluing laminated color boxes according to claim 1, characterized in that, The water-based adhesive comprises a high glass transition temperature styrene-acrylic non-film-forming emulsion, a solid acrylic alkali-soluble resin, a water-based leveling agent, ethanol, a water-based wetting agent, a water-based defoamer, a water-based abrasion resistant agent, a water-based slip agent, pure acrylic emulsion, and water.

4. The method for gluing laminated color boxes according to claim 3, characterized in that, The method for preparing the high glass transition temperature styrene-acrylic non-film-forming emulsion, by weight parts, includes: A monomer phase is prepared by mixing 40-60 parts of styrene, 10-20 parts of butyl acrylate and 15-25 parts of methyl methacrylate. An aqueous phase is prepared by mixing 80-120 parts of deionized water, 1-3 parts of anionic emulsifier and 0.5-2 parts of nonionic emulsifier. The monomer phase and the aqueous phase are then mixed to form a pre-emulsion. The preemulsion is divided into a first preemulsion and a second preemulsion, and the ammonium persulfate initiator, with a total dosage of 0.3 to 0.8 parts, is divided into a first initiator and a second initiator. The first preemulsion and the first initiator are added to the reaction system, and the temperature is raised to 75~85℃ to initiate polymerization to form a seed emulsion. Then the second preemulsion and the second initiator are added dropwise, and the dropwise addition time is controlled to be 2~4h and the reaction temperature is 80±5℃. After the addition is complete, keep warm for 1-2 hours, cool down to below 40°C, adjust the pH to 7.5-8.5 with ammonia, and filter to obtain the high glass transition temperature styrene-acrylic non-film-forming emulsion.

5. The method for gluing laminated color boxes according to claim 3, characterized in that, The preparation method of the solid acrylic alkali-soluble resin, by weight, includes: Mix 25-35 parts of acrylic acid, 10-20 parts of methacrylic acid, 30-50 parts of styrene and 40-60 parts of isopropanol, and heat to 85-95°C under nitrogen protection; A solution of isopropanol containing 1-3 parts of benzoyl peroxide was added dropwise, and the mixture was refluxed for 3-5 hours until the acid value reached 80-120 mg KOH / g. The mixture was then cooled to below 60°C, and the reaction solution was added dropwise to deionized water to precipitate the solid acrylic alkali-soluble resin. After centrifugation, washing, vacuum drying, and pulverization, the solid acrylic alkali-soluble resin was obtained.

6. The method for gluing laminated color boxes according to claim 3, characterized in that, The method for preparing the water-based adhesive, by weight parts, includes: Add 8-15 parts of solid alkali-soluble acrylic resin to 20-30 parts of deionized water, stir and dissolve at 60-70℃, and adjust the pH to 8.0-9.0 with ammonia water to obtain a resin solution; 25-35 parts of a high glass transition temperature styrene-acrylic non-film-forming emulsion were mixed with 15-25 parts of a pure acrylic emulsion to obtain a mixed emulsion; The resin solution is added to the mixed emulsion for mixing, and then 0.3-0.8 parts of water-based leveling agent, 0.5-1.5 parts of water-based wetting agent, 0.2-0.5 parts of water-based defoamer, 1-3 parts of water-based abrasion-resistant agent and 0.5-1.5 parts of water-based slip agent are added in sequence. Then 3-8 parts of ethanol are added, and the mixture is filtered to obtain the water-based adhesive.

7. The method for gluing laminated color boxes according to claim 1, characterized in that, The first pressing pressure is 0.2~0.4MPa.

8. The method for gluing laminated color boxes according to claim 1, characterized in that, The second pressing pressure is 0.6~0.8MPa.

9. The method for gluing laminated color boxes according to claim 1, characterized in that, The curing and shaping are carried out at a temperature of 25±5℃ and a relative humidity of 60±10%.

10. The method for gluing laminated color boxes according to claim 9, characterized in that, The curing and setting time shall not be less than 24 hours.

Images