Production process of two-component in-situ reaction heat and ionic crosslinking moisture-proof carton

Abstract

The invention relates to the technical field of paper product processing, and discloses a two-component in-situ reaction heat and ionic crosslinking moisture-proof carton production process which comprises the following steps: performing compression molding on corrugated base paper; the method comprises the following steps: coating an acidic high-solid-content slurry containing citric acid, calcium chloride and corn starch as a component A on a corrugation peak of the corrugating medium paper; coating the inner surface of the cardboard paper with an alkaline initiation solution containing sodium hydroxide and sodium alginate as a component B; and converging and pressing the two, initiating an acid-base neutralization reaction and an ionic cross-linking reaction on a contact interface, and curing, cutting and forming to obtain the finished product of the moisture-proof carton. According to the method, starch in-situ gelatinization is driven by chemical enthalpy heat instantly released by reaction, external steam heating is replaced, energy consumption is reduced, and buckling deformation of the paperboard caused by high-temperature baking is eliminated; and meanwhile, the starch matrix is wrapped by the calcium alginate gel network generated in situ, so that the moisture resistance and the wet bonding strength of the carton are improved.

Description

Technical Field

[0001] This invention relates to the field of paper product processing technology, specifically to a two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process. Background Technology

[0002] Corrugated cardboard boxes are common packaging containers in the logistics and transportation industry. The manufacturing process of corrugated cardboard relies on starch adhesive to bond the corrugated core paper to the linerboard. Traditional starch adhesives require a specific gelatinization temperature to produce adhesion. Corrugated cardboard production lines use steam hot plate systems to heat the cardboard. This external heat source conduction heating method consumes a large amount of steam and electricity, which not only increases production costs but also causes the cardboard fibers to be in a state of high temperature and dehydration for a long time. Excessive drying of the cardboard fibers will generate internal stress. The release of internal stress makes the finished corrugated cardboard prone to warping and deformation, reducing the flatness of the cardboard and affecting the processing accuracy of subsequent printing and forming processes.

[0003] Starch molecules are rich in hydrophilic groups, which makes starch adhesives prone to absorbing moisture and swelling in humid environments. The strength of the adhesive layer decreases after absorbing moisture, making corrugated boxes prone to collapse or delamination in high humidity environments. Although increasing the concentration of crosslinking agent can enhance the water resistance of starch adhesive layers, high concentrations of crosslinking agent react rapidly when mixed with starch, shortening the pot life of the adhesive. In actual production, in order to prevent the adhesive from solidifying prematurely in the glue tank or conveying pipeline, it is necessary to reduce the content or activity of the active ingredients, which limits the application of high-strength, fast-drying formulations on high-speed automated production lines.

[0004] Therefore, this invention proposes a two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process to overcome the shortcomings of the prior art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process, which solves the problems of high energy consumption, easy warping and deformation of cardboard due to high-temperature baking, and poor moisture resistance of starch adhesives in existing corrugated cardboard box production processes.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A two-component in-situ reactive thermal and ionic crosslinking moisture-proof cardboard box manufacturing process includes the following steps:

[0008] S1. The corrugated base paper is introduced into the corrugated roller group for pressing to obtain corrugated core paper;

[0009] S2. Apply the acidic high-solids latent slurry as component A to the top of the flute of the corrugated core paper to obtain corrugated core paper with component A coating.

[0010] S3. Apply the alkaline initiating film-forming solution as component B to the inner surface of the linerboard to obtain linerboard with component B coating.

[0011] S4. Combine and press the corrugated core paper with component A coating with the linerboard with component B coating to make component A and component B react at the interface to obtain wet corrugated cardboard.

[0012] S5. The wet corrugated cardboard is cured, cut and shaped to obtain the finished moisture-proof cardboard box.

[0013] By adopting the above technical solution, the present invention utilizes the principle of converting chemical energy into heat energy and rapid ion cross-linking to achieve a low-temperature, rapid, and moisture-resistant bonding effect.

[0014] Preferably, in step S2, the raw materials of component A include the following parts by weight:

[0015] Deionized water: 50.0-65.0 parts;

[0016] Citric acid monohydrate: 0.8-2.5 parts;

[0017] Anhydrous calcium chloride: 3.0-8.0 parts;

[0018] Corn starch: 28.0-42.0 parts.

[0019] By employing the above technical solution, citric acid monohydrate serves as a proton donor, providing an acidic environment and enthalpy potential for the neutralization reaction; anhydrous calcium chloride acts as a crosslinking agent source, remaining dissolved in the acidic environment to store calcium ions for subsequent gel skeleton formation; and a high proportion of corn starch maintains low viscosity in its ungelatinized state, increasing the solid content of component A. This high-solids-content formulation design reduces the amount of free water in the system, lowers the drying load of the subsequent curing process, and improves initial adhesion.

[0020] Preferably, in step S3, the raw materials for component B include the following parts by weight:

[0021] Deionized water: 85.0-95.0 parts;

[0022] Polyvinyl alcohol: 0.5-1.5 parts;

[0023] Sodium hydroxide: 3.0-7.0 parts;

[0024] Sodium tetraborate decahydrate: 0.5-1.5 parts;

[0025] Sodium alginate: 1.5-4.0 parts.

[0026] By adopting the above technical solution, sodium hydroxide acts as an initiator, neutralizing citric acid monohydrate and releasing heat upon contact; sodium alginate acts as a framework building agent, combining with diffused calcium ions to form a dense three-dimensional network gel layer; polyvinyl alcohol and sodium tetraborate decahydrate work synergistically to regulate the rheological properties of component B and improve the film-forming properties of component B on the surface of linerboard, preventing excessive penetration of the adhesive into the paper fibers and ensuring that the reaction occurs at the bonding interface.

[0027] Preferably, the preparation steps of component A include:

[0028] While stirring, mix deionized water, citric acid monohydrate and anhydrous calcium chloride until the solid particles dissolve. Add corn starch and disperse at 400-1000 rpm for 20-30 minutes to form a suspension.

[0029] Component A has a pH of 3.0-4.0 and a Stormer viscosity of 16-24 seconds at 25 degrees Celsius.

[0030] By adopting the above technical solution, controlling the pH value to 3.0-4.0 can inhibit the swelling of starch granules at room temperature and ensure that component A is in a stable latent state; using a dispersion speed of 400-1000 rpm can prevent starch sedimentation or agglomeration in high solid content systems, obtain a uniformly dispersed suspension, and ensure the uniformity of coating amount.

[0031] Preferably, the preparation steps of component B include:

[0032] Heat deionized water to 85-95 degrees Celsius, add polyvinyl alcohol, keep warm and stir until dissolved, then cool to below 40 degrees Celsius, add sodium hydroxide to dissolve and cool to room temperature, then add sodium tetraborate decahydrate to dissolve.

[0033] Finally, sodium alginate was added and stirred until no particulate agglomerates were found. The resulting component B had a pH of 12.5-13.5 and a Brookfield viscosity of 180-850 mPa·s at 25 degrees Celsius.

[0034] By adopting the above technical solutions, the stepwise dissolution process avoids competitive dissolution or agglomeration between components; controlling the pH value to 12.5-13.5 ensures that component B has sufficient chemical potential energy to trigger a vigorous neutralization exothermic reaction; controlling the viscosity in the range of 180-850 mPa·s makes component B suitable for both spraying and roller coating, and can maintain good surface retention.

[0035] Preferably, in step S1, the temperature at which the corrugated rollers press is 110-130 degrees Celsius.

[0036] By adopting the above technical solution, a pressing temperature of 110-130 degrees Celsius is sufficient to complete the physical shaping of the corrugated base paper. At the same time, combined with the subsequent cold bonding process, the paper is prevented from becoming brittle due to continuous exposure to high temperatures.

[0037] Preferably, in step S2, the wet adhesive coating amount of component A is 8-12 g / m², and in step S3, the wet adhesive coating amount of component B is 2-5 g / m².

[0038] By adopting the above technical solution, the total coating amount of component A and component B is controlled at a low level. At the same time, by utilizing the high solids content, the moisture introduced into the paperboard is minimized, thereby shortening the time for the paperboard to reach moisture equilibrium and improving production efficiency.

[0039] Preferably, in step S4, the production line speed for merging and pressing is 150-300 m / min, and the composite line pressure for merging and pressing is 3-7 kgf / cm².

[0040] By adopting the above technical solution, at a high speed of 150-300m / min, the composite line pressure of 3-7kgf / cm² can ensure that component A and component B fully penetrate, mix and complete the interface reaction in a very short contact time, thus ensuring the establishment of instantaneous initial tack and meeting the needs of modern high-speed corrugated board production lines.

[0041] Preferably, in step S3, the coating method for component B includes atomized spraying or roller coating.

[0042] By adopting the above technical solutions, atomized spraying or roller coating can uniformly cover the inner surface of the linerboard with component B, forming a continuous alkaline initiation layer. This ensures that the reaction points are evenly distributed when in contact with component A on the corrugated peaks, avoiding local non-bonding or fluctuations in bonding strength.

[0043] This invention provides a two-component in-situ reactive thermal and ionic crosslinking process for manufacturing moisture-proof cardboard boxes. It offers the following advantages:

[0044] 1. This invention initiates an acid-base neutralization reaction at the bonding interface, using the enthalpy heat released instantaneously by the chemical reaction as a heat source to drive in-situ gelatinization of starch. This endogenous heating method replaces the external conduction heating link of the steam hot plate in the traditional corrugated cardboard production line, reducing steam and electricity consumption in the production process, eliminating the high-temperature baking process to avoid internal stress caused by excessive water loss of cardboard fibers, solving the problem of warping and deformation of cardboard produced by traditional processes, and improving the flatness of the finished cardboard.

[0045] 2. This invention utilizes the ion exchange reaction between calcium chloride and sodium alginate at the bonding interface to construct a water-insoluble calcium alginate gel network. The calcium alginate gel network coats and supports the gelatinized starch molecular chains, blocking the erosion of the starch bonding layer by environmental moisture. The dual mechanism of in-situ thermal gelatinization and ion cross-linking curing improves the retention rate of the adhesive strength of corrugated boxes in humid environments, ensuring the structural stability of the boxes under high humidity storage and transportation conditions.

[0046] 3. This invention employs an off-site coating mode that physically isolates the acidic slurry from the alkaline initiating liquid, allowing the two components to come into contact and react only at the moment of pressing. The off-site coating mode prevents the problem of glue solidification or reduced activity caused by pre-mixing of high-activity formulations, ensuring the continuity and stability of the production process. The high-solids content formulation design reduces the total amount of moisture introduced into the paperboard during production, shortens the time required for the paperboard to reach moisture balance, and improves the operating efficiency of the production line. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, examples, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] Preparation Examples 1-6:

[0049] Preparation Example 1:

[0050] This preparation example provides an optimally proportioned acidic high-solids latent slurry, denoted as Component A1. During preparation, 60.0 kg of deionized water was added to a reactor equipped with a mechanical stirrer. The stirrer was started and the speed was set to 400 rpm. 1.5 kg of citric acid monohydrate and 5.0 kg of anhydrous calcium chloride were added sequentially, and stirring was continued for 10 minutes until the solid particles were completely dissolved. At this point, the pH of the solution was measured to be 3.5. Subsequently, while maintaining stirring, 35.0 kg of corn starch was slowly added, and the stirring speed was adjusted to 800 rpm to prevent starch settling. Dispersion was continued for 20 minutes until a uniform milky white suspension was formed. The theoretical solids content of the prepared slurry Component A1 was approximately 40.9%, the pH was 3.5, the Stormer viscosity at 25 degrees Celsius was 18 seconds, it was in a latent state of unswelled raw starch, and the calcium ions were evenly distributed.

[0051] Preparation Example 2:

[0052] This preparation example provides an acidic, high-solids latent slurry with high solids content and high ionic strength, denoted as Component A2. During preparation, 50.0 kg of deionized water, 2.5 kg of citric acid monohydrate, and 8.0 kg of anhydrous calcium chloride were added to a reactor. After stirring and dissolving, the pH of the bottom solution was measured to be 3.0. Subsequently, 42.0 kg of corn starch was added and dispersed for 30 minutes under high-speed stirring at 1000 rpm. The resulting slurry Component A2 has a theoretical solids content of approximately 51.2%, a pH of 3.0, and a Stormer viscosity of 24 seconds at 25 degrees Celsius. It exhibits extremely high crosslinking agent reserves and starch filling density, making it suitable for high-strength paperboard production.

[0053] Preparation Example 3:

[0054] This preparation example provides a low-solids, weakly acidic, high-solids latent slurry, denoted as Component A3. During preparation, 65.0 kg of deionized water, 0.8 kg of citric acid monohydrate, and 3.0 kg of anhydrous calcium chloride were added to a reaction vessel. After stirring and dissolving, the pH of the bottom solution was measured to be 4.0. Subsequently, 28.0 kg of corn starch was added, and the mixture was stirred and dispersed for 20 minutes. The theoretical solids content of the prepared slurry Component A3 was approximately 32.8%, the pH was 4.0, and the Stormer viscosity at 25°C was 16 seconds, exhibiting excellent flow and penetration properties, suitable for rapid penetration into low-basis-weight corrugated paper.

[0055] Preparation Example 4:

[0056] This preparation example provides an optimally formulated alkaline initiating film-forming solution, denoted as Component B1. During preparation, 90.0 kg of deionized water was added to a stirred tank equipped with a heating mantle, and the temperature was raised to 85-95 degrees Celsius. 1.0 kg of polyvinyl alcohol was added, and the mixture was stirred and kept at this temperature for 30 minutes until completely dissolved. The temperature was then lowered to below 40 degrees Celsius. 5.0 kg of sodium hydroxide was added, stirred until dissolved, and allowed to cool naturally to room temperature, where the pH was measured to be 13.0. Next, 1.0 kg of sodium tetraborate decahydrate was added and stirred until completely dissolved. Finally, the stirring speed was adjusted to 600 rpm, and 2.5 kg of sodium alginate was slowly and evenly added, with continuous stirring for 60 minutes until no particulate agglomerates remained. The resulting film-forming solution, Component B1, was a pale yellow, transparent, viscous liquid with a Brookfield viscosity of 350 mPa·s at 25 degrees Celsius, exhibiting suitable rheological properties.

[0057] Preparation Example 5:

[0058] This preparation example provides an alkaline initiating film-forming solution with high alkalinity and high skeleton strength, denoted as component B2. During preparation, 85.0 kg of deionized water is added to a stirred tank, and 1.5 kg of polyvinyl alcohol is dissolved at 85-95 degrees Celsius according to the above process. After cooling, 7.0 kg of sodium hydroxide is added, and after cooling to room temperature, 1.5 kg of sodium tetraborate decahydrate is added to dissolve. Finally, 4.0 kg of sodium alginate is added for dissolution and dispersion. The obtained film-forming solution, component B2, has a pH of 13.5 and a Brookfield viscosity of 850 mPa·s at 25 degrees Celsius, exhibiting extremely high chemical reaction potential and film-forming strength, making it suitable for high-pressure spraying or transfer roller coating processes.

[0059] Preparation Example 6:

[0060] This preparation example provides a low-alkalinity and low-viscosity alkaline initiating film-forming solution, denoted as component B3. During preparation, 95.0 kg of deionized water is added to a stirred tank, and 0.5 kg of polyvinyl alcohol is dissolved according to the above process. After cooling, 3.0 kg of sodium hydroxide is added, followed by further cooling and the addition of 0.5 kg of sodium tetraborate decahydrate. Finally, 1.5 kg of sodium alginate is added for dissolution. The resulting film-forming solution, component B3, has a pH of 12.5 and a Brookfield viscosity of 180 mPa·s at 25°C, exhibiting excellent atomization performance and is suitable for economical production modes with low coating weights.

[0061] Examples 1-5:

[0062] Example 1:

[0063] This embodiment provides a two-component in-situ reaction thermal and ionic crosslinking moisture-proof cardboard box manufacturing process, including the following steps:

[0064] S1, the quantitative amount is 120g / m 2 High-strength corrugated base paper is introduced into the corrugated roll group of a single-face corrugating machine and pressed at a physical shaping temperature of 120 degrees Celsius to obtain corrugated core paper with a continuous wavy structure.

[0065] S2. Using a coating roller, apply the acidic high-solids latent slurry (component A 1) prepared in Example 1 to the top of the flute peaks of the corrugated core paper obtained in step S1, controlling the coating gap to ensure a wet adhesive coating amount of 10 g / m². 2 Corrugated core paper with component A coating was obtained;

[0066] S3. Using a high-pressure atomizing spraying device, the alkaline initiating film-forming solution (component B1) prepared in Example 4 is uniformly sprayed onto a substrate with a quantitative amount of 175 g / m³. 2 The inner surface of the kraft linerboard is coated with wet adhesive at a rate of 3 g / m². 2 Corrugated board with component B coating was obtained;

[0067] S4. At the pressure roller, the corrugated core paper with component A coating obtained in step S2 is combined with the linerboard with component B coating obtained in step S3. The production line speed is set to 200 m / min, and the pressure is 5 kgf / cm². 2 Under the composite line pressure, the acidic high solids latent slurry (component A 1) and the alkaline initiating film-forming liquid (component B 1) undergo an interfacial contact reaction. The contact reaction time is 20 milliseconds. The enthalpy heat released by the reaction initiates in-situ gelatinization of starch and forms a calcium alginate gel network, resulting in a wet corrugated cardboard with strong initial adhesion.

[0068] S5. The initially bonded wet corrugated cardboard obtained in step S4 is naturally balanced and cured through a room temperature conveyor. Then it is cut and creasing by a longitudinal and transverse cutter. After folding, gluing and packing, the finished moisture-proof cardboard box is obtained.

[0069] Example 2:

[0070] This embodiment provides a two-component in-situ reaction thermal and ionic crosslinking moisture-proof cardboard box manufacturing process, including the following steps:

[0071] S1, the quantitative amount is 120g / m 2 High-strength corrugated base paper is introduced into the corrugated roll assembly and pressed at a temperature of 130 degrees Celsius to obtain corrugated core paper with a continuous wavy structure.

[0072] S2. Using a coating roller, the acidic high-solids latent slurry (component A 2) prepared in Example 2 is coated onto the top of the flute peaks of the corrugated core paper obtained in step S1, with the wet coating amount set to 12 g / m². 2 Corrugated core paper with component A coating was obtained;

[0073] S3. Using a micro-transfer roller, the alkaline initiating film-forming solution (component B2) prepared in Example 5 is coated onto a substrate with a basis weight of 175 g / m³. 2 The inner surface of the kraft linerboard is coated with a wet adhesive at a rate of 4 g / m². 2 Corrugated board with component B coating was obtained;

[0074] S4. The corrugated core paper with component A coating obtained in step S2 and the linerboard with component B coating obtained in step S3 are combined at the pressure roller. The production line speed is set to 300 m / min, and the pressure is 7 kgf / cm. 2 Under high composite line pressure, instantaneous pressing is achieved, utilizing high concentrations of acid and alkali components to rapidly release a large amount of reaction heat and form a high-density cross-linked network, resulting in high-strength initially bonded wet corrugated cardboard.

[0075] S5. The high-strength initially bonded wet corrugated cardboard obtained in step S4 is dried using an auxiliary micro-wind drying device, followed by cutting, creasing, folding and joining to obtain a high-strength finished moisture-proof cardboard box.

[0076] Example 3:

[0077] This embodiment provides a two-component in-situ reaction thermal and ionic crosslinking moisture-proof cardboard box manufacturing process, including the following steps:

[0078] S1, the quantitative amount is 120g / m 2 High-strength corrugated base paper is introduced into the corrugated roll assembly and pressed at a temperature of 110 degrees Celsius to obtain corrugated core paper with a continuous wavy structure.

[0079] S2. Using a coating roller, the acidic high-solids latent slurry (component A 3) prepared in Example 3 is coated onto the top of the corrugated core paper obtained in step S1, with the wet coating amount set to 8 g / m². 2 Corrugated core paper with component A coating was obtained;

[0080] S3. Using a spraying device, the alkaline initiating film-forming solution (component B 3) prepared in Example 6 is sprayed onto a surface with a quantitative amount of 175 g / m³. 2 The inner surface of the kraft linerboard is coated with a wet adhesive at a rate of 2 g / m². 2 Corrugated board with component B coating was obtained;

[0081] S4. The corrugated core paper with component A coating obtained in step S2 and the linerboard with component B coating obtained in step S3 are combined at the pressure roller. The production line speed is set to 150 m / min, and the pressure is 3 kgf / cm. 2 The composite line pressure is used for pressing to obtain a wet corrugated cardboard with a strong initial bond;

[0082] S5. The initially bonded wet corrugated cardboard obtained in step S4 is naturally cured at room temperature via a conveyor belt. Then, it is cut, shaped and packaged in a conventional manner to obtain an economical finished moisture-proof cardboard box.

[0083] Example 4:

[0084] This embodiment provides a two-component in-situ reactive thermal and ionic crosslinking moisture-proof cardboard box production process to verify the cross-compatibility of high-calcium, low-skeleton formulations, including the following steps:

[0085] S1. The corrugated base paper is pressed into shape at high temperature to obtain corrugated core paper with a continuous wavy structure.

[0086] S2. Using a coating roller, the acidic high-solids latent slurry (component A 2) prepared in Example 2 is coated onto the top of the flute peaks of the corrugated core paper obtained in step S1. The wet coating amount is 11 g / m². 2 Corrugated core paper with component A coating was obtained;

[0087] S3. Using a spraying device, the alkaline initiating film-forming solution (component B 3) prepared in Example 6 is coated onto the inner surface of kraft linerboard, with a wet coating amount of 3 g / m². 2 Corrugated board with component B coating was obtained;

[0088] S4. The corrugated core paper with component A coating obtained in step S2 and the linerboard with component B coating obtained in step S3 are subjected to a speed of 200 m / min and a pressure of 5 kgf / cm². 2 Pressing under pressure and using excess calcium ions to gel the sodium alginate layer resulted in rapidly shaped wet corrugated cardboard.

[0089] S5. The quick-setting wet corrugated cardboard obtained in step S4 is processed through subsequent conventional processes to obtain the finished moisture-proof cardboard box.

[0090] Example 5:

[0091] This embodiment provides a two-component in-situ reactive thermal and ionic crosslinking moisture-proof cardboard box production process for verifying the cross-compatibility of low-calcium, high-skeleton formulations, including the following steps:

[0092] S1. The corrugated base paper is pressed into shape at high temperature to obtain corrugated core paper with a continuous wavy structure.

[0093] S2. Using a coating roller, the acidic high-solids latent slurry (component A 3) prepared in Example 3 is coated onto the top of the corrugated core paper obtained in step S1. The wet coating amount is 9 g / m². 2 Corrugated core paper with component A coating was obtained;

[0094] S3. Using a roller coating device, the alkaline initiating film-forming solution (component B2) prepared in Example 5 is coated onto the inner surface of kraft linerboard, with a wet coating amount of 5 g / m². 2 Corrugated board with component B coating was obtained;

[0095] S4. The corrugated core paper with component A coating obtained in step S2 and the linerboard with component B coating obtained in step S3 are subjected to a speed of 200 m / min and a pressure of 6 kgf / cm². 2 High-toughness wet corrugated cardboard was obtained by pressing under pressure and forming a dense film layer with calcium ions using a high-viscosity sodium alginate layer.

[0096] S5. The high-toughness wet corrugated cardboard obtained in step S4 is processed through subsequent conventional processes to obtain the finished moisture-proof cardboard box.

[0097] Comparative Examples 1-5:

[0098] Comparative Example 1:

[0099] Compared to Example 1, the difference lies in the change of the adhesive system and curing process:

[0100] The acidic high-solids latent slurry (component A1) in S2 was replaced with an oxidized starch adhesive (22% solids content, pH 11.0) prepared using a conventional one-component starch adhesive process, and the wet coating weight was increased to 28 g / m². 2 ;

[0101] Eliminate step S3 and do not perform any coating operations on the linerboard;

[0102] In step S4, instead of using the heat of chemical reaction, the composite cardboard is introduced into a steam hot plate drying tunnel with a temperature set at 175 degrees Celsius for forced heating and drying. The length of the drying tunnel is 15 meters. The remaining steps are the same as in Example 1.

[0103] Comparative Example 2:

[0104] The difference compared to Example 1 is the removal of the key raw material that generates the in-situ reaction enthalpy:

[0105] When preparing component A, citric acid monohydrate was not added; starch and calcium chloride were directly dispersed in deionized water to obtain neutral component A (pH 7.0).

[0106] When preparing component B, sodium hydroxide was not added; only polyvinyl alcohol, borax, and sodium alginate were dissolved to obtain neutral component B (pH 7.5).

[0107] In the S4 step of the composite process, when component A comes into contact with component B, an acid-base neutralization exothermic reaction cannot occur. The bonding is achieved solely through room temperature physical penetration and ionic cross-linking. The remaining steps are the same as in Example 1.

[0108] Comparative Example 3:

[0109] Compared to Example 1, the difference lies in the removal of the key raw material for generating the ionic crosslinking framework:

[0110] When preparing component A, no anhydrous calcium chloride is added; only acidic starch slurry is prepared.

[0111] When preparing component B, sodium alginate is not added; only an alkaline initiation solution is prepared.

[0112] In the S4 step of the compounding process, although the contact between component A and component B can generate heat of acid-base reaction and gelatinize starch, it cannot form a calcium alginate gel network skeleton. The remaining steps are the same as in Example 1.

[0113] Comparative Example 4:

[0114] Compared to Example 1, the difference lies in the change of the off-site coating process:

[0115] Instead of the independent spraying in step S3, we attempted to premix the acidic high-solids latent slurry (component A 1) of Preparation Example 1 and the alkaline initiating film-forming liquid (component B 1) of Preparation Example 4 in a glue bath at a mass ratio of 10:3 before step S2. After mixing, we applied the mixture directly to the corrugated core paper using a coating roller.

[0116] In actual operation, violent gelation occurs instantly upon mixing, causing the adhesive to lose its fluidity and making it impossible to coat normally. This comparative example is used to demonstrate the necessity of the off-site process. The remaining steps are the same as in Example 1.

[0117] Comparative Example 5:

[0118] Compared to Example 1, the difference is that the starch matrix was removed, and only the gel component was retained:

[0119] In step S2, the acidic high-solids latent slurry (component A1) is replaced with an equal mass of acidic calcium chloride aqueous solution (without corn starch), attempting to achieve adhesion solely by the calcium alginate gel layer. The remaining steps are the same as in Example 1.

[0120] Test Example 1-2:

[0121] Test Example 1:

[0122] This test case mainly verifies the enthalpy effect and reaction rate of the acid-base in situ reaction described in this invention. By simulating actual contact conditions, the peak temperature rise and the initial adhesion establishment time of the system are measured.

[0123] A polyurethane foam container with good thermal insulation properties was used, and a high-sensitivity K-type thermocouple probe was pre-placed inside the container. 10.0 grams of component A corresponding to Examples 1, 2, and 3 were weighed and placed into the container. Then, 3.0 grams of the corresponding component B were rapidly injected using a syringe, while simultaneously starting a magnetic stirrer at 500 rpm. The highest temperature value of the mixture from the moment of contact until the temperature dropped was recorded. For Comparative Example 2, neutral components A and B were mixed in the same proportion for testing.

[0124] The pressing process on a simulated production line was conducted in a laboratory environment at a constant temperature of 25 degrees Celsius. An automatic coating machine was used to coat component A onto a corrugated paper sample strip (coating amount as in the previous example), and component B onto a linerboard sample strip. The two paper samples were then bonded together under a set pressure. After bonding, a T-shaped peel test was performed at four time points: 0.5 seconds, 1.0 seconds, 2.0 seconds, and 5.0 seconds. The peel failure interface was observed; if more than 85% of the paper fibers were torn, it was considered completely broken, and the shortest time required to reach this state was recorded.

[0125] The test data is as follows:

[0126] Table 1. Raw material ratios of components A and B in each embodiment and comparative example.

[0127] Group Initial temperature of component A (degrees Celsius) Peak temperature after mixing (degrees Celsius) Temperature rise ΔT (degrees Celsius) Time required for the paper to completely break (s) Remark Example 1 25.1 82.4 57.3 0.5 The reaction was rapid, with a small amount of water vapor escaping. Example 2 25.0 91.6 66.6 <0.5 It solidifies instantly and feels noticeably warm to the touch. Example 3 25.2 74.3 49.1 1.0 The temperature rise is moderate, and the curing is relatively fast. Comparative Example 2 25.1 26.8 1.7 >60.0 There is no obvious heat release; the adhesive is fluid and does not dry for a long time.

[0128] The test results are analyzed as follows:

[0129] As shown in Table 1, in Examples 1, 2, and 3, the temperature of the mixing system increased by 57.3°C, 66.6°C, and 49.1°C respectively at the instant of contact between component A and component B. The peak temperatures all exceeded the gelatinization initiation temperature of corn starch (approximately 62°C to 72°C). The measured peak mixing temperatures of 74.3°C to 91.6°C directly confirm that the chemical enthalpy heat released by acid-base neutralization is sufficient to drive in-situ gelatinization of starch without an external heat source. Conversely, Comparative Example 2, which removed the acid and base components, only experienced a temperature rise of 1.7°C (due to physical mixing heat or environmental error), resulting in a paper breakage time exceeding 60 seconds. Correspondingly, the dry adhesive strength of Comparative Example 2 in Table 2 was only 42 N / m, indicating complete adhesive failure. This demonstrates that the heat of chemical reaction is the energy basis for achieving cold bonding in this technical solution.

[0130] The experimental results of Comparative Example 4 show that the premixing operation directly led to the curing and scrapping of the adhesive. This proves that the ex-situ coating process, which isolates the active components until they come into contact at the pressing interface, is the path to achieve the engineering application of highly reactive formulations.

[0131] Test Example 2:

[0132] This test case evaluates the physical properties and energy consumption of the corrugated cardboard prepared in each embodiment and comparative example according to national standards and industry-standard methods.

[0133] According to GB / T6548-2011 "Determination of Bonding Strength of Corrugated Board", the bonding strength between the flute peaks and the face paper was determined using a compressive strength tester. Ten samples were cut for each sample, and the average value was taken.

[0134] The cut samples were placed in a constant temperature and humidity chamber, with the temperature set at 30 degrees Celsius and the relative humidity at 90%. After 24 hours of treatment, the samples were removed and the adhesive strength test was completed within 30 seconds. The specific wet adhesive strength retention rate is the percentage ratio of the wet adhesive strength value to the dry adhesive strength value.

[0135] Take a 1m x 1m cardboard sample and place it flat on a horizontal surface. Measure the maximum warpage height at the four corners and center of the cardboard. The smaller the value, the better the flatness.

[0136] The amount of steam and electricity consumed by the production line to produce 10,000 square meters of cardboard under stable operating conditions was statistically analyzed. Using the energy consumption of Comparative Example 1 (traditional hot plate heating process) as a baseline of 100%, the relative energy consumption percentages for other groups were calculated.

[0137] The test data is as follows:

[0138] Table 2: Performance test results of finished cartons for each embodiment and comparative example.

[0139] Group Dry bond strength (N / m) Wet bond strength retention rate (%) Cardboard warpage height (mm) Relative energy consumption index (%) Remark Example 1 583 76.4 2.1 8.5 The cardboard has good stiffness and no buckling. Example 2 642 81.2 3.5 11.2 Extremely strong, the cardboard is sturdy. Example 3 515 68.9 1.8 6.4 Meets basic requirements and has extremely low energy consumption. Example 4 608 72.5 2.6 9.1 Good adaptability Example 5 576 79.8 2.3 9.8 Good toughness Comparative Example 1 540 12.3 18.6 100.0 The cardboard was over-dried and warped significantly. Comparative Example 2 42 0.0 -- 7.2 The adhesive failed, the glue naturally detached, and it could not be molded. Comparative Example 3 488 18.5 5.2 8.3 The glue came unglued quickly after getting damp. Comparative Example 4 -- -- -- -- The adhesive solidifies in the glue tank and cannot be applied to the machine. Comparative Example 5 215 35.6 4.1 8.8 Insufficient strength, cardboard is soft

[0140] Note: The symbol "--" in the table indicates no data.

[0141] The test results are analyzed as follows:

[0142] As can be seen from the data of Comparative Example 1 and Comparative Example 3, both exhibit acid-base reaction heat, resulting in little difference in dry adhesive strength (583 N / m vs. 488 N / m). However, after 24 hours of high-humidity treatment, the wet adhesive strength retention rate of Example 1 reached 76.4%, while that of Comparative Example 3 was only 18.5%. Comparative Example 3 lacked the gel network formed by calcium ions and sodium alginate, making the gelatinized starch prone to disintegration after absorbing moisture. The examples demonstrated that the calcium alginate gel network coated and supported the starch particles, preventing moisture erosion of the starch molecular chains and confirming the crucial role of the dual curing mechanism in improving moisture resistance.

[0143] Compared with Comparative Example 1, the relative energy consumption index of each embodiment is below 12%, achieving an energy saving effect of nearly 90%. At the same time, since the embodiments abandon high-temperature baking, the cardboard fibers do not generate internal stress due to excessive water loss. The warpage height of Embodiment 1 in Table 2 is only 2.1 mm, which is much lower than 18.6 mm of Comparative Example 1, solving the technical problems of easy warping and bursting of cardboard in traditional processes.

[0144] In summary, this invention achieves low-energy, high-strength, and moisture-resistant production of corrugated boxes by constructing an acidic high-solids latent system and an alkaline initiation system, utilizing the dual mechanisms of instantaneous reaction enthalpy heat gelatinization and ionic cross-linking curing.

Claims

1. A two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box manufacturing process, characterized in that, Includes the following steps: S1. The corrugated base paper is introduced into the corrugated roller group for pressing to obtain corrugated core paper; S2. Apply the acidic high-solids latent slurry as component A to the top of the flute peaks of the corrugated core paper to obtain corrugated core paper with component A coating. S3. Apply the alkaline initiating film-forming solution as component B to the inner surface of the linerboard to obtain linerboard with component B coating. S4. The corrugated core paper with component A coating and the linerboard with component B coating are combined and pressed together, so that component A and component B undergo an interfacial contact reaction to obtain wet corrugated cardboard. S5. The wet corrugated cardboard is cured, cut and shaped to obtain the finished moisture-proof cardboard box.

2. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S2, component A is made from raw materials comprising the following parts by weight: Deionized water: 50.0-65.0 parts; Citric acid monohydrate: 0.8-2.5 parts; Anhydrous calcium chloride: 3.0-8.0 parts; Corn starch: 28.0-42.0 parts.

3. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S3, component B is made from raw materials comprising the following parts by weight: Deionized water: 85.0-95.0 parts; Polyvinyl alcohol: 0.5-1.5 parts; Sodium hydroxide: 3.0-7.0 parts; Sodium tetraborate decahydrate: 0.5-1.5 parts; Sodium alginate: 1.5-4.0 parts.

4. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 2, characterized in that, Component A is prepared in advance through the following steps: Under stirring, the deionized water, the citric acid monohydrate and the anhydrous calcium chloride are mixed until the solid particles dissolve. The corn starch is then added and dispersed at 400-1000 rpm for 20-30 minutes to form a suspension. The pH value of component A is 3.0-4.0, and the Stormer viscosity at 25 degrees Celsius is 16-24 seconds.

5. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 3, characterized in that, Component B is prepared in advance through the following steps: The deionized water is heated to 85-95 degrees Celsius, the polyvinyl alcohol is added, and the mixture is kept warm and stirred until dissolved. Then the temperature is lowered to below 40 degrees Celsius, the sodium hydroxide is added to dissolve, and the mixture is cooled to room temperature. Then the sodium tetraborate decahydrate is added to dissolve. Finally, add the sodium alginate and stir until there are no particulate agglomerates. The resulting component B has a pH of 12.5-13.5 and a Brookfield viscosity of 180-850 mPa·s at 25 degrees Celsius.

6. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S1, the temperature at which the corrugated roller assembly is pressed is 110-130 degrees Celsius.

7. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S2, the wet coating amount of component A is 8-12 g / m². 2 In step S3, the wet coating amount of component B is 2-5 g / m³. 2 .

8. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S4, the speed of the production line for merging and pressing is 150-300 m / min.

9. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S4, the composite linear pressure of the merging and pressing is 3-7 kgf / cm. 2 .

10. The two-component in-situ reaction thermal and ion crosslinking moisture-proof cardboard box production process according to claim 1, characterized in that, In step S3, the coating method of component B includes either atomized spraying or roller coating.