Disposable hand-torn garbage bobbin paper base formula and preparation method thereof

Abstract

The invention discloses a formula of a disposable hand-torn garbage bobbin paper base. The paper base comprises raw paper, and a latent hardening sizing layer and a micro-rough oil-proof layer which are sequentially coated on the surface of the raw paper, wherein the sizing layer is composed of a film-forming base material, ammonium bicarbonate, an ammonium zirconium carbonate solution and a volatile alkaline agent, and the pH value of the system is 9.0-9.8; the preparation method comprises the following steps: after sizing, maintaining an alkaline latent state in a low-temperature drying manner, coating the oil-proof layer for pre-curing, cutting and stacking, and then feeding into a mold for hot press molding. And hot-pressing high-temperature triggers decomposition of ammonium bicarbonate to drive the pH value of the system to reverse so as to promote crosslinking hardening of ammonium zirconium carbonate and a film-forming base material. A chemical latent mechanism is utilized to solve the contradiction between easy cracking of deep stamping forming and insufficient rigidity of a finished product, and interlayer friction is reduced through a surface micro-rough structure, so that the finished product has excellent rigidity and anti-adhesion performance, and easy hand tearing separation is realized.

Description

Technical Field

[0001] This invention relates to the field of paper product processing technology, specifically to the paper base formulation and preparation method of disposable tear-off waste trays. Background Technology

[0002] Disposable paper-based containers are widely used in household waste collection and catering packaging due to their good biodegradability and recycling value. In particular, tabletop trash cans based on high-temperature resistant silicone paper (commonly used in air fryers, baking, etc.) are usually provided to consumers in the form of multiple stacks. They are peeled off one sheet at a time and are required to have a certain structural strength to bear household waste such as fruit peels and paper scraps. At the same time, they need to meet the basic functions of oil resistance, water resistance, and seepage prevention to meet the needs of bearing wet household waste such as fruit peel juice.

[0003] In existing industrial production systems, the manufacturing of such products typically follows a process route of "coating the base paper, drying, cutting, and stamping." To impart the necessary barrier properties and physical strength to the paper, manufacturers coat the surface of the base paper with functional coatings. After removing moisture through hot air drying or oven drying, the paper is wound up, then slit into sheets, and finally fed into a metal mold to press the flat paper blank into a disc with a three-dimensional shape using mechanical pressure. This process requires the paper base material to possess surface characteristics suitable for coating and winding, as well as to withstand the physical deformation requirements of subsequent die stamping.

[0004] However, existing technologies face a challenge in manufacturing high-stiffness deep-drawn paper products: achieving a balance between molding performance and final rigidity. To ensure the waste tray doesn't collapse under load, high levels of crosslinking agents or hardening resins are typically added to the formulation to increase the paper's modulus. However, these reinforcing components often solidify and crosslink due to heat during the drying stage after coating, causing the paper to harden and lose its flexibility before entering the stamping process. When this pre-hardened paper undergoes deep stretching or complex folding in the mold, the fiber network cannot adapt to the intense deformation stress, easily leading to brittle fracture or visible cracks at the bottom edge or corners of the tray, severely impacting yield. Conversely, reducing the amount of hardener to avoid stamping cracks solves the molding problem but results in insufficient rigidity in the final product, leading to a poor user experience. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a paper base formula and preparation method for disposable tear-off garbage trays. This solves the problems that existing disposable paper base containers are prone to paper cracking or insufficient rigidity in the finished product due to mismatch between the timing of glue application and curing and the molding process during hot pressing. Furthermore, the finished products are prone to interlayer adhesion and are difficult to separate when stacked.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides a disposable tear-off waste tray paper base formula, employing the following technical solution: A disposable tear-off waste tray paper base formulation, wherein the paper base includes base paper, and a latent hardening sizing layer and a micro-roughened oil-resistant layer sequentially coated on the surface of the base paper.

[0007] The latent curing sizing layer is formed by curing a latent curing sizing solution containing the following components in parts by weight: 100 parts of film-forming substrate; 3.0-6.0 parts of ammonium bicarbonate; 10.0-15.0 parts of ammonium zirconium carbonate solution; and a volatile alkali agent for adjusting the pH of the system to 9.0-9.8.

[0008] The micro-roughened oil-resistant layer is formed by curing a micro-roughened oil-resistant coating liquid containing the following components in parts by weight: 100 parts vinyl silicone oil; 1.5-3.0 parts micro-roughness modifier; 1.2-2.0 parts hydrogen-containing silicone oil; 1.5-2.0 parts platinum catalyst solution; and 0.04-0.05 parts inhibitor.

[0009] By adopting the above technical solution, this invention utilizes the pH-controlled delayed crosslinking characteristics and the surface micro-roughness structure to synergistically solve the compatibility problem between the processing performance and the performance of paper-based materials. The specific mechanism is as follows: Chemical control of latent curing adhesive layers: Alkalinity suppression: Ammonium bicarbonate and a volatile alkali agent are introduced into the formulation to construct an alkaline buffer system with a pH of 9.0-9.8. Under this environment, the zirconium ions in ammonium zirconium carbonate exist stably in the form of zirconium carbonate anionic complexes, and their cross-linking reactivity with hydroxyl groups in the film-forming substrate is suppressed. This chemically latent state ensures that the sized paper maintains its flexibility during low-temperature drying and winding, preventing premature cross-linking and hardening that could lead to breakage during subsequent stamping.

[0010] Thermally initiated crosslinking: When hot-pressed into a high-temperature mold, ammonium bicarbonate decomposes to produce ammonia, carbon dioxide, and water. As ammonia and carbon dioxide escape, the pH value inside the sizing layer changes from alkaline to neutral or weakly acidic. The decrease in pH value disrupts the stability of ammonium zirconium carbonate, prompting it to release active zirconium species, which undergo polydentate coordination crosslinking reactions with the hydroxyl groups on the molecular chains of the film-forming substrate. This results in the in-situ formation of a three-dimensional network structure with high crosslinking density on the surface of the paper fibers, thereby improving the wet strength retention and rigidity of the finished product.

[0011] Gas-assisted release: The trace amounts of gas produced by the decomposition of ammonium bicarbonate during hot pressing form an air film between the paper fibers and the mold, which helps reduce adhesion and assists in the demolding of the finished product.

[0012] Surface modification of micro-roughened oil-resistant coating: Construction of roughness: By dispersing micro-roughness modifiers in a vinyl silicone oil system, a non-smooth surface is constructed using microscopic protrusions of particles on the coating surface. This micro-rough structure reduces the actual contact area between layers when paper trays are stacked, disrupting the closed adsorption state that easily forms between smooth surfaces.

[0013] Reduce the coefficient of friction: Combined with the low surface energy characteristics of the silicone coating, the micro-rough structure reduces the static friction coefficient between layers, enabling stacked paper trays to be separated into individual sheets with less external force, thus improving the anti-sticking performance of the finished product.

[0014] Preferably, the film-forming substrate is polyvinyl alcohol or oxidized starch; the effective component of the zirconium carbonate ammonium solution has a content of 19.0%-21.0% based on zirconium dioxide; and the volatile alkali agent is ammonia.

[0015] By adopting the above technical solution and selecting ammonia water as a regulator, its high volatility is utilized to ensure rapid discharge from the system during hot pressing, thereby achieving a rapid reduction in pH value and improving production efficiency.

[0016] Preferably, the micro-roughness modifier is hydrophilic fumed silica or calcined diatomaceous earth; the Si-H / Vi molar ratio of the hydrogen-containing silicone oil is 1.5:1-2.0:1.

[0017] By adopting the above technical solution, hydrophilic fumed silica or calcined diatomaceous earth has a suitable specific surface area and particle size, forming a physical support in the silicone oil coating, which not only ensures the anti-sticking effect, but also maintains the continuity of the anti-oil coating.

[0018] Preferably, the single-sided dry weight coating amount of the latent curing adhesive layer is 0.5-0.8 g / m². 2 The coating amount of the micro-roughened oil-resistant layer is 0.8-1.2 g / m². 2 .

[0019] By adopting the above technical solution, this coating amount range achieves optimization of performance and material consumption. Within this range, the adhesive application amount provides sufficient reinforcement without increasing the drying load; within this range, the oil-resistant coating amount ensures impermeability and prevents re-tack.

[0020] Preferably, the pH value of the paper surface of the finished product is 6.8-7.2, and the interlayer peel force is 0.14-0.19 N / 25 mm. By adopting the above technical solution, the finished product is neutral, indicating that alkaline volatiles have escaped, which meets the safety requirements of food contact materials; the above-mentioned interlayer peel force range ensures that the finished product has good tear-resistant properties.

[0021] Secondly, the present invention provides a method for preparing a disposable tear-off waste tray paper base formula, which adopts the following technical solution: The preparation method of the disposable tear-off waste tray paper base formula includes the following steps: S1. Form a wet paper web and dry it to obtain the base paper; S2. Apply the latent curing sizing solution to the surface of the base paper obtained in step S1, and dry it at a controlled temperature to make the sizing layer in an alkaline latent state, thus obtaining the sizing base paper. S3. Apply the slightly roughened oil-resistant coating liquid to the surface of the sizing base paper obtained in step S2, and pre-cur it under controlled temperature to obtain roll paper. S4. Cut the roll of paper obtained in step S3 into paper blanks and stack multiple sheets of paper blanks. S5. The stacked paper blanks obtained in step S4 are fed into the mold for hot pressing. The high temperature of the mold triggers the decomposition of ammonium bicarbonate to produce gas and the cross-linking and hardening of ammonium zirconium carbonate. The finished product is obtained by demolding.

[0022] By adopting the above technical solution, this invention establishes a staged temperature-controlled processing technology to regulate the chemical reaction process: Low-temperature latency and pre-curing (steps S2-S3): During the coating and intermediate processing stages, a low drying temperature is controlled. This stage only removes moisture and initially cures the silicone oil layer, while the ammonium bicarbonate in the sizing layer does not decompose significantly, and the system remains alkaline. This allows the paper web to maintain a low modulus of flexibility, adapting to mechanical processing operations such as winding and slitting.

[0023] High-temperature triggering and setting (step S5): High temperature and high pressure are applied in the final forming stage. The high temperature activates the latent cross-linking system, allowing the paper to complete the transformation from flexible to rigid within the mold; the high pressure ensures the bonding between the paper fibers and the cross-linking network. This process path, which separates the processing flexibility from the final hardening and reinforcement, solves the process requirement difference between hot pressing and high hardness indicators.

[0024] Preferably, the method for preparing the latent curing sizing solution is as follows: dissolve the film-forming substrate in water to prepare a base solution, add ammonium bicarbonate to dissolve, adjust the pH value of the system to 9.0-9.8 using a volatile alkali agent, and finally add ammonium zirconium carbonate solution and adjust the viscosity while stirring.

[0025] By adopting the above technical solution and using the feeding sequence of first adjusting the alkali and then adding the crosslinking agent, it is ensured that ammonium zirconium carbonate is in an inhibiting environment when it is added, preventing local gelation during the preparation process and ensuring the storage stability of the adhesive solution.

[0026] Preferably, the temperature control in steps S2 and S3 includes: in step S2, the drying temperature does not exceed 95°C; in step S3, the pre-curing temperature is 105-115°C; the temperature control is used to ensure that the ammonium bicarbonate in the adhesive layer does not completely decompose before hot pressing in step S5.

[0027] By adopting the above technical solution, the drying temperature below 95℃ effectively reduces the thermal decomposition loss of ammonium bicarbonate; the pre-curing temperature of 105-115℃ combined with short-term heating only triggers a slight reaction on the surface, which not only achieves rapid curing of silicone oil, but also retains most of the latent activity inside the adhesive layer, leaving room for reaction in subsequent hot pressing curing.

[0028] Preferably, the mold temperature is 140-170℃, the molding pressure is 3.0-5.0MPa, and the holding time is 2-5 seconds. By adopting the above technical solution, these process parameters provide sufficient energy to complete chemical cross-linking and physical shaping, while avoiding thermal degradation of the paper base.

[0029] This invention provides a formulation for disposable tear-off waste tray paper base and its preparation method. It has the following beneficial effects: 1. This invention introduces an alkaline latent system composed of ammonium bicarbonate and volatile alkali agents into a latent hardening sizing layer. The chemical inertness of ammonium zirconium carbonate in an alkaline environment at low temperatures effectively inhibits the cross-linking reaction, maintaining the excellent flexibility and elongation of the base paper during coating and winding processes. This prevents fiber breakage caused by premature hardening and brittleness of the paper during deep drawing. Furthermore, under the high-temperature stimulation of subsequent hot pressing, the rapid escape of volatile components drives the pH value of the system to change from alkaline to neutral, prompting ammonium zirconium carbonate to release active zirconium species and rapidly complete multidentate coordination cross-linking and curing with the film-forming substrate. This significantly improves the final rigidity and moisture resistance of the finished product while effectively solving the technical problem of poor adaptability of paper-based materials to deep drawing processes.

[0030] 2. This invention disperses a micro-roughness modifier in a micro-roughness-resistant layer and combines it with a specific proportion of hydrogen-containing silicone oil in a vinyl silicone oil system. By utilizing inorganic particles to construct a uniform micro-roughness structure on the coating surface, it effectively reduces the interlayer contact area when the finished products are stacked and stores, and disrupts the vacuum-sealed adsorption state that is easily formed between smooth surfaces. Combined with the low surface energy characteristics of organosilicon, it significantly reduces the interlayer static friction coefficient, enabling multiple stacked paper trays to maintain good looseness without the need for release paper. This ensures that users can easily tear and separate individual sheets with extremely low peeling force, avoiding the phenomenon that traditional coated paper trays cannot be properly separated and used due to tight interlayer adhesion.

[0031] 3. This invention employs a staged temperature-controlled preparation process. During the sizing, drying, and pre-curing stages of the anti-oil layer, the temperature is strictly controlled below the violent decomposition temperature of ammonium bicarbonate. This ensures that the sizing layer maintains sufficient latent chemical activity before entering the mold, avoiding the loss of crosslinking agent caused by the pre-reaction. In the hot pressing stage, the latent system is activated instantaneously by the high temperature of the mold, allowing gas generation and chemical crosslinking to proceed simultaneously. The expansion pressure generated by the gas assists in the paper's adhesion to the mold and promotes demolding. This achieves a precise match between the chemical reaction process and the physical processing steps, improving production efficiency while ensuring the consistency and stability of the finished product's physical properties.

[0032] 4. The finished product obtained by this invention inherits the hydrophobic properties and heat resistance stability of the silicone coating, and has excellent waterproof and anti-permeability capabilities. This allows the paper plate to not only effectively hold liquid kitchen waste (such as watermelon rinds and juicy fruit shells), but also safely hold high-temperature residues of freshly cooked food (such as hot bones) without being scalded or deformed, fully meeting the diverse needs for temperature resistance and waterproofing in desktop cleaning scenarios. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation process of the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0036] Both bleached sulfate softwood pulp and bleached sulfate hardwood pulp are commercially available general-purpose papermaking grade wood pulp boards; polyvinyl alcohol is commercially available PVA-1799 type, with a degree of alcoholysis of 98.0%~99.0% and an average degree of polymerization of 1700~1800; oxidized starch is commercially available papermaking grade, with a whiteness ≥90% and a viscosity of 20~50 mPa·s; ammonium zirconium carbonate solution is commercially available industrial grade product, with an effective component content of 19.0%~21.0% based on zirconium dioxide and a pH value of 9.0~10.0; ammonium bicarbonate is commercially available food grade, with a purity ≥99.5%; ammonia water is commercially available analytical grade, with a concentration of 25.0%~28.0%.

[0037] The vinyl silicone oil is a commercially available vinyl-terminated polydimethylsiloxane with a viscosity of 300-500 mPa·s and a vinyl content of 0.15%-0.25%; the hydrogen-containing silicone oil is a commercially available side-chain hydrogen-containing polymethylsiloxane with an active hydrogen content of 0.8%-1.2%; the platinum catalyst is a commercially available Karstedt catalyst xylene solution with a platinum content of 3000-5000 ppm; the inhibitor is 1-ethynyl-1-cyclohexanol with a purity ≥99.0%; the fumed silica is a commercially available hydrophilic type with a specific surface area of ​​150-200 m². 2 / g; Calcined diatomaceous earth is a commercially available product with an average particle size D50 of 3~6μm; Polyamide epichlorohydrin resin is a commercially available wet strength agent for papermaking with a solid content of 12.5%±0.5%.

[0038] Preparation Example Preparation Example 1: This preparation example provides a latent curing sizing agent, the preparation steps of which are as follows: (1) Add 940 parts of deionized water to a reactor equipped with a stirrer and a temperature control device, heat to 90°C, slowly add 60 parts of polyvinyl alcohol (PVA-1799) while stirring, continue stirring for 45 minutes until completely dissolved, then cool to 35°C to obtain a PVA base liquid with a solid content of 6%. (2) Add 1.8 parts of ammonium bicarbonate (3.0% of the mass of PVA) to the above base solution and stir until completely dissolved; (3) Adjust the pH of the system to 9.0 using ammonia; (4) Slowly add 6.0 parts of zirconium carbonate ammonium solution (AZC, the effective component is 20% zirconium dioxide, that is, the amount of AZC added is 10.0% of the mass of PVA) while stirring. After stirring evenly, add water to adjust the final viscosity to 18 mPa·s to obtain latent curing sizing solution A1.

[0039] Preparation Example 2: This preparation example provides a latent curing sizing agent, the preparation steps of which are as follows: (1) Add 940 parts of deionized water to the reactor, heat to 92°C, add 60 parts of polyvinyl alcohol (PVA-1799), stir to dissolve, and then cool to 35°C to obtain PVA base liquid; (2) Add 2.7 parts of ammonium bicarbonate (4.5% of the mass of PVA) to the above base solution and stir until completely dissolved; (3) Adjust the pH of the system to 9.4 using ammonia; (4) Slowly add 7.5 parts of zirconium carbonate solution (the amount of AZC stock solution added is 12.5% ​​of the mass of PVA) while stirring. After stirring evenly, add water to adjust the final viscosity to 20 mPa·s to obtain latent curing sizing solution A2.

[0040] Preparation Example 3: This preparation example provides a latent curing sizing agent, the preparation steps of which are as follows: (1) Add 940 parts of deionized water to the reactor, heat to 95°C, add 60 parts of polyvinyl alcohol (PVA-1799), stir to dissolve, and then cool to 35°C to obtain PVA base liquid; (2) Add 3.6 parts of ammonium bicarbonate (6.0% of the mass of PVA) to the above base solution and stir until completely dissolved; (3) Adjust the pH of the system to 9.8 using ammonia; (4) Slowly add 9.0 parts of zirconium carbonate solution (the amount of AZC stock solution added is 15.0% of the mass of PVA) while stirring. After stirring evenly, add water to adjust the final viscosity to 22 mPa·s to obtain the latent curing sizing solution A3.

[0041] Preparation Example 4: This preparation example provides a latent curing sizing agent (starch-based), and its preparation steps are as follows: (1) Add 920 parts of deionized water to the reactor, heat to 95°C, add 80 parts of oxidized starch, keep warm and stir for 60 minutes to gelatinize, cool to 40°C, and obtain starch base liquid with 8% solid content; (2) Add 3.6 parts of ammonium bicarbonate (4.5% of the starch mass) to the above base solution and stir until completely dissolved; (3) Adjust the pH of the system to 9.5 using ammonia; (4) Slowly add 10.0 parts of zirconium carbonate solution (the amount of AZC stock solution added is 12.5% ​​of the starch mass) while stirring, and after stirring evenly, the latent hardening sizing solution A4 is obtained.

[0042] Preparation Example 5: This preparation example provides a micro-roughened oil-resistant coating liquid, the preparation steps of which are as follows: (1) Add 100 parts of vinyl silicone oil to a dispersion tank and add 1.5 parts of fumed silica (accounting for 1.5% of the silicone oil mass). (2) Start the high shear disperser and disperse at 2500 rpm for 15 minutes until no visible agglomerated particles are visible; (3) Add 1.2 parts of hydrogen-containing silicone oil (Si-H / Vi molar ratio controlled at 1.5:1), 0.04 parts of inhibitor and 1.5 parts of platinum catalyst solution to the dispersion (to ensure an effective platinum content of about 50-70 ppm). (4) Stir at low speed to mix evenly, and degas under vacuum at -0.09MPa for 10 minutes to obtain micro-rough oil-proof coating liquid B1.

[0043] Preparation Example 6: This preparation example provides a micro-roughened oil-resistant coating liquid, the preparation steps of which are as follows: (1) Add 100 parts of vinyl silicone oil to a dispersion tank and add 2.2 parts of fumed silica (accounting for 2.2% of the silicone oil mass). (2) High-shear dispersion at 2500 rpm for 15 minutes; (3) Add 1.4 parts of hydrogen-containing silicone oil (Si-H / Vi molar ratio controlled at 1.7:1), 0.04 parts of inhibitor and 1.8 parts of platinum catalyst solution to the dispersion; (4) Mix evenly and degas under vacuum to obtain micro-rough oil-proof coating liquid B2.

[0044] Preparation Example 7: This preparation example provides a micro-roughened oil-resistant coating liquid, the preparation steps of which are as follows: (1) Add 100 parts of vinyl silicone oil to a dispersion tank and add 3.0 parts of calcined diatomaceous earth (accounting for 3.0% of the silicone oil mass). (2) Disperse at 2000 rpm for 15 minutes; (3) Add 1.6 parts of hydrogen-containing silicone oil (Si-H / Vi molar ratio controlled at 2.0:1), 0.05 parts of inhibitor and 2.0 parts of platinum catalyst solution to the dispersion; (4) Mix evenly and degas under vacuum to obtain micro-rough oil-proof coating liquid B3.

[0045] Example Example 1: This embodiment provides a method for preparing a disposable tear-off trash tray based on a pH thermal reversal mechanism, using the sizing solution A2 from Preparation Example 2 and the coating solution B2 from Preparation Example 6. The specific steps are as follows: (1) Using 35% softwood pulp and 65% hardwood pulp as raw materials, 1.0% PAE wet strength agent is added, and the basis weight is 40 g / m² on a fourdrinier paper machine. 2 The wet paper width of the base paper; (2) Apply latent curing sizing agent A2 to both sides of the base paper using a surface sizing machine. The sizing amount (dry weight) on one side is controlled at 0.6 g / m² (total 1.2 g / m² for both sides). 2 ); (3) The sized paper web is sent into a multi-stage drying cylinder for drying. The maximum surface temperature of the drying cylinder is strictly controlled to be 90°C. The paper is dried until the moisture content is 5% to obtain the base paper A. (4) Using a five-roll coater, the micro-roughened oil-resistant coating liquid B2 is coated on one side of the base paper A, with a coating amount of 1.0 g / m². 2 Then it is placed in a 110°C suspension oven for 20 seconds to cure, and then wound into a roll of paper; (5) Cut the roll of paper into circular blanks and stack them in groups of 20; (6) The stacked paper blanks are fed into the mold of the semi-automatic paper tray machine. The mold temperature is set to 160℃, the forming pressure is 4.0MPa, and the holding time is 3 seconds. The high temperature triggers the decomposition of ammonium bicarbonate to produce gas and the cross-linking and hardening of AZC. The finished product is obtained after demolding.

[0046] Example 2: This embodiment provides a method for preparing a disposable tear-off garbage tray, aiming to verify the lower limit of process parameters and low-ratio formulation. The sizing solution A1 from Preparation Example 1 and the coating solution B1 from Preparation Example 5 are used. The specific steps are as follows: (1) The amount of paper made according to the same proportions as in Example 1 is 38g / m 2 The base paper; (2) Apply latent curing sizing agent A1 to both sides of the base paper, with a total sizing amount of 1.0 g / m². 2 (3) Control the drying temperature of the drying cylinder to a maximum of 85℃ to prevent premature reaction; (4) Apply the slightly roughened oil-resistant coating liquid B1 to one side of the base paper, with a coating amount of 0.8 g / m. 2 Cured at 105℃ for 25 seconds; (5) Stack the cut paper blanks in groups of 10 sheets; (6) Set the mold temperature to 140℃, the molding pressure to 3.0MPa, and the holding time to 5 seconds for in-situ hot pressing molding.

[0047] Example 3: This embodiment provides a method for preparing a disposable tear-off garbage tray, aiming to verify the upper limit of process parameters and high-ratio formulation. It uses the sizing liquid A3 from Preparation Example 3 and the coating liquid B3 from Preparation Example 7. The specific steps are as follows: (1) The amount of paper made according to the same proportions as in Example 1 is 42 g / m 2 The base paper; (2) Apply latent curing sizing agent A3 to both sides of the base paper, with a total sizing amount of 1.5 g / m². 2 ; (3) The drying temperature of the drying cylinder should be controlled to a maximum of 95℃; (4) Apply the slightly roughened oil-resistant coating liquid B3 to one side of the base paper, with a coating amount of 1.2 g / m. 2 Cured at 115℃ for 15 seconds; (5) Stack the cut paper blanks in groups of 30 sheets; (6) Set the mold temperature to 170℃, the molding pressure to 5.0MPa, and the holding time to 2 seconds for in-situ hot pressing molding.

[0048] Example 4: This embodiment provides a method for preparing a disposable tear-off garbage tray, using a starch-based sizing solution system, employing sizing solution A4 from Preparation Example 4 and coating solution B2 from Preparation Example 6. The specific steps are as follows: (1) The papermaking quantity is 40g / m 2 The base paper; (2) Apply starch-based latent hardening sizing agent A4 to both sides of the base paper, with a total sizing amount of 1.2 g / m². 2 ; (3) The drying temperature of the drying cylinder should be controlled to a maximum of 90℃; (4) Apply the slightly roughened oil-resistant coating liquid B2 to one side of the base paper, with a coating amount of 1.0 g / m. 2 Cured at 110℃ for 20 seconds; (5) Stack the cut paper blanks in groups of 20 sheets; (6) Set the mold temperature to 155℃, the molding pressure to 4.0MPa, and the holding time to 3 seconds for in-situ hot pressing molding.

[0049] The following is a comparative example designed based on the aforementioned embodiments, aiming to comprehensively compare and verify the technical effects of the pH thermal reversal latent system and the micro-roughness oil-resistant system.

[0050] Comparative Example 1: This comparative example provides a conventional method for preparing silicone-based paper, serving as a blank control.

[0051] The difference compared to Example 1 is as follows: Replacement of sizing agent: Use a pure polyvinyl alcohol (PVA) solution (6% solid content) without zirconium carbonate (AZC) and ammonium bicarbonate to replace the latent curing sizing agent A2. It only provides basic film-forming properties and does not have thermosetting crosslinking function.

[0052] Coating liquid replacement: Replace the micro-roughening anti-oil coating liquid B2 with a pure vinyl silicone oil system that does not contain fumed silica, while keeping the other components and proportions unchanged.

[0053] The remaining preparation processes are the same as in Example 1.

[0054] Comparative Example 2: This comparative example aims to verify the necessity of a pH inhibitor (ammonium bicarbonate) in the latent mechanism.

[0055] The difference compared to Example 1 is as follows: In the preparation of the latent curing sizing solution, no ammonium bicarbonate was added, and only ammonia was used to adjust the pH value to 9.4. Due to the lack of a high-concentration buffer environment provided by ammonium bicarbonate, AZC underwent a cross-linking reaction prematurely during the heating process of drying the base paper (step 3) and curing the silicone oil (step 4) due to the rapid volatilization of ammonia.

[0056] The remaining preparation processes are the same as in Example 1.

[0057] Comparative Example 3: This comparative example aims to verify the effect of micro-roughness friction modifiers on interlayer separation performance.

[0058] The difference compared to Example 1 is as follows: In the preparation process of the micro-roughness oil-resistant coating liquid, no fumed silica was added, and the resulting coating surface was a smooth planar silicone oil layer.

[0059] The remaining preparation processes are the same as in Example 1.

[0060] Comparative Example 4: This comparative example aims to verify the uniqueness of the pH reversal mechanism triggered by volatile alkali agents.

[0061] The difference compared to Example 1 is as follows: In the preparation of the latent curing sizing solution, sodium hydroxide (NaOH) is used instead of ammonium bicarbonate to adjust the pH of the system to 9.4. Since sodium hydroxide is a non-volatile strong alkali, it cannot decompose and escape like ammonium bicarbonate during hot pressing molding, resulting in the system maintaining a strong alkaline environment at high temperature, inhibiting the crosslinking reaction of AZC and the negative transition of pH value.

[0062] The remaining preparation processes are the same as in Example 1.

[0063] Comparative Example 5: This comparative example aims to verify the importance of low-temperature control in the process flow.

[0064] The difference compared to Example 1 is as follows: Adjust the silicone oil curing process in step (4) and set the temperature of the suspension oven to 150℃ (the high-temperature curing condition for conventional silicone oil). At this temperature, the ammonium bicarbonate in the sizing layer has already undergone violent decomposition before entering the mold, causing the paper to harden prematurely during the coating process.

[0065] The remaining preparation processes are the same as in Example 1.

[0066] Test Example 1: Feasibility Verification of Chemical Latency Mechanism and In-situ Solidification This test case verifies the response characteristics of the pH thermal reversal and thermal release latent curing mechanism described in this invention during the processing, and examines the changes in surface acidity and alkalinity, physical crosslinking degree and mechanical rigidity of paper-based materials at different thermal history stages.

[0067] Three node samples from the preparation process of Example 1 were selected for testing: Node A is the semi-finished base paper after drying in step (3); Node B is the roll paper after silicone oil coating and low-temperature curing in step (4); Node C is the finished product after high-temperature hot pressing in step (6).

[0068] The experimental steps are as follows: The surface pH value was measured using a pH meter equipped with a planar composite electrode. 0.05 mL of distilled water was added to the surface of the sample to be tested, and the sample was allowed to stand for 30 seconds to allow a water film to form. The electrode probe was then placed against the wetted area, and the reading was recorded after it stabilized. Ten different locations were measured at each node, and the average value was taken.

[0069] According to GB / T 465.2-2008 standard, the wet strength retention rate was determined to characterize the degree of crosslinking curing. The sample was cut into strips 15 mm wide and long. The dry tensile strength after constant temperature and humidity equilibrium and the wet tensile strength after immersion in distilled water at 20℃ for 1 hour were measured. The ratio of wet tensile strength to dry tensile strength was calculated.

[0070] According to GB / T 23144-2008 standard, the longitudinal bending moment value of the sample was determined using a stiffness tester.

[0071] The content of residual ammonium ions was determined by ion chromatography. A quantitative sample was soaked in deionized water and ultrasonically extracted. The concentration of ammonium ions in the extract was measured and converted into the residual amount in the paper.

[0072] Table 1: Physicochemical properties of samples at different process stages: The conclusions drawn from the analysis of the data in Table 1 are as follows: Data shows that the surface pH value of node A is maintained in an alkaline range of about 9.3, indicating that the decomposition degree of ammonium bicarbonate is low during the low-temperature drying stage of the base paper. The system environment inhibits the cross-linking activity of ammonium zirconium carbonate. At this time, the wet strength retention rate of the sample is less than 5%, and the bending stiffness is about 2.1 mN·m, indicating that the paper is in a non-cross-linked flexible state.

[0073] The pH value at node B dropped to around 8.8, and the residual ammonium ion content decreased from about 860 mg / kg to about 610 mg / kg. This indicates that during the 110°C curing process of silicone oil coating, some ammonium bicarbonate decomposed, but the system remained alkaline. The wet strength retention rate only increased slightly to about 8%, and no large-scale cross-linking occurred. At this stage, the physical properties of the paper were suitable for winding and slitting, and no brittleness problem caused by premature curing occurred.

[0074] Data from node C shows that after hot pressing at 160℃, the surface pH value drops to a neutral level of 7.07, and the residual ammonium ion content drops to about 40 mg / kg, indicating that ammonium bicarbonate decomposes and escapes in the high-temperature mold. At the same time, the wet strength retention rate jumps to about 39%, and the flexural stiffness increases to over 12.4 mN·m. The sudden change in physical properties and the decrease in pH value are synchronous in the process, confirming that the crosslinking reaction is triggered in situ during the hot pressing step.

[0075] In summary, this technical solution utilizes temperature control to regulate the decomposition of ammonium bicarbonate and pH changes, achieving latent stability of the sizing agent during the coating and winding stages, as well as rapid cross-linking and hardening during the forming stage. This resolves the process contradiction between flexible paper processing and rigid shaping of the finished product. The low detection rate of residual ammonium ions also confirms that the reaction gas has been discharged during the hot pressing process.

[0076] Test Example 2: Comprehensive Product Performance Comparison Test This test case aims to compare the actual application performance of the paper discs prepared in each embodiment and comparative example, focusing on rigidity retention, interlayer separation characteristics and stacking stability.

[0077] 1. Testing Method Shape retention (springback test): The hot-pressed paper trays were placed in an environment with a relative humidity of 50% and a temperature of 23°C for 24 hours, and the change in the depth of the paper trays before and after placement was measured.

[0078] Calculation formula: Shape retention rate = (depth after 24 hours / depth just out of mold) × 100%. The higher the value, the better the shaping effect and the smaller the springback.

[0079] Bending stiffness (sturdiness): Select a flat area on the edge of the paper tray to cut a sample, and test the longitudinal stiffness according to GB / T 23144 standard, or use a simplified test method: fix one side of the paper tray and suspend it in the air, apply a 50g load to the suspended end, and measure the drooping displacement (mm). The smaller the displacement, the higher the stiffness.

[0080] Interlayer peel strength (tearability): Cut the stacked paper trays into 25mm wide strips and perform a 180-degree peel test using a universal testing machine. Record the average force (N / 25mm) required to separate a single layer of paper tray from the stack. Too much force indicates that the paper is stuck together and difficult to tear, while too little force indicates that the bond is not tight.

[0081] Stacking stability (anti-slip angle): Stack 10 paper trays on an adjustable inclined plane, slowly raise the angle of the inclined plane, and record the critical angle at which the upper layer of paper trays begins to slip relative to each other. The larger the angle, the better the anti-slip stability.

[0082] Oil resistance: Refer to the TAPPI T559 standard (Kit method), use mixed solvents of different grades to drop onto the coating surface, observe whether there is penetration or wetting, and record the highest non-penetration level (level 1-12).

[0083] 2. Test Results Table 2: Performance Comparison Data of Finished Products from Examples and Comparative Examples 3. Results Analysis The conclusions drawn from the analysis of the data in Table 2 are as follows: Regarding molding rigidity and shape retention: Examples 1-4 all exhibited shape retention rates above 97%, with edge sag displacement controlled within 2.5 mm, demonstrating excellent rigidity and shaping ability. In contrast, Comparative Example 1 (unmodified PVA) showed a shape retention rate of only about 45%, with severe sag, failing to meet the paper tray stiffness requirements. Comparative Example 2 (without ammonium bicarbonate inhibition) cracked prematurely due to paper embrittlement upon mold closure, resulting in an incomplete finished product. This conversely demonstrates the necessity of the latent inhibitor. Although Comparative Example 4 used an alkaline regulator (NaOH), its lack of thermal volatility hindered the pH environment required for subsequent crosslinking, leading to a finished product with significantly lower rigidity (sag of 8.6 mm) compared to the examples. The above data fully confirm that this invention utilizes chemical reinforcement methods to achieve low basis weight (such as the 38-42 g / m² used in the examples). 2 The thin base paper can achieve the stiffness of traditional high-grammage paperboard after hot pressing, thus significantly reducing raw material costs while ensuring product performance, achieving true low cost and disposableness.

[0084] Regarding interlayer separation and stacking stability: The interlayer peel force of the example group was stable between 0.14-0.19 N / 25 mm, and the anti-slip angle was greater than 30°, achieving a balance between easy tearing and stable stacking.

[0085] The peel force of Comparative Example 3 (without fumed silica) surged to 0.92 N / 25 mm, and the anti-slip angle was only 6°. This indicates that the lack of micro-rough structure leads to a vacuum adsorption effect between layers (making peeling difficult), while the insufficient coefficient of friction causes the stack to slip easily.

[0086] The peel force of Comparative Example 5 (high temperature pre-curing) is as high as 1.45 N / 25 mm. This is because the coating was completely cured before entering the mold, and lost the auxiliary separation effect of the gas micro-layer during the hot pressing process, resulting in thermal adhesion between the layers.

[0087] In summary, this invention, through specific component combinations and process control, ensures excellent oil resistance while solving core technical problems in the prior art, such as insufficient rigidity of paper trays, easy breakage during deep drawing, and difficulty in separating interlayer adhesion.

[0088] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A disposable tear-off waste tray paper base formula, characterized in that, The paper base includes a base paper, and a latent hardening sizing layer and a micro-roughened oil-resistant layer sequentially coated on the surface of the base paper; The latent curing sizing layer is formed by curing a latent curing sizing liquid containing the following components in parts by weight: 100 parts of film-forming substrate; 3.0-6.0 parts of ammonium bicarbonate; 10.0-15.0 parts of ammonium zirconium carbonate solution; And volatile alkali agents used to adjust the pH of the system to 9.0-9.8; The micro-roughened oil-resistant layer is formed by curing a micro-roughened oil-resistant coating liquid containing the following components in parts by weight: 100 parts vinyl silicone oil; Fine roughness modifier 1.5-3.0 parts; 1.2-2.0 parts of hydrogen-containing silicone oil; 1.5-2.0 parts of platinum catalyst solution; Inhibitor 0.04-0.05 parts.

2. The disposable tear-off waste tray paper base formula according to claim 1, characterized in that, The film-forming substrate is polyvinyl alcohol or oxidized starch; the effective component of the zirconium ammonium carbonate solution is 19.0%-21.0% based on zirconium dioxide; and the volatile alkali agent is ammonia.

3. The disposable tear-off waste tray paper base formula according to claim 1, characterized in that, The micro-roughness modifier is hydrophilic fumed silica or calcined diatomaceous earth; the Si-H / Vi molar ratio of the hydrogen-containing silicone oil is 1.5:1-2.0:

1.

4. The disposable tear-off waste tray paper base formula according to claim 1, characterized in that, The single-sided dry weight coating amount of the latent curing adhesive layer is 0.5-0.8 g / m². 2 The coating amount of the micro-roughened oil-resistant layer is 0.8-1.2 g / m². 2 .

5. The finished product prepared according to the disposable tear-off waste tray paper base formula according to any one of claims 1-4, characterized in that, The finished paper has a surface pH value of 6.8-7.2 and an interlayer peel strength of 0.14-0.19 N / 25 mm.

6. A method for preparing the disposable tear-off waste tray paper base formulation according to claim 1, characterized in that, Includes the following steps: S1. Form a wet paper web and dry it to obtain the base paper; S2. Apply the latent curing sizing solution to the surface of the base paper obtained in step S1, and dry it at a controlled temperature to make the sizing layer in an alkaline latent state, thus obtaining the sizing base paper. S3. Apply the slightly roughened oil-resistant coating liquid to the surface of the sizing base paper obtained in step S2, and pre-cur it under controlled temperature to obtain roll paper. S4. Cut the roll of paper obtained in step S3 into paper blanks and stack multiple sheets of paper blanks. S5. The stacked paper blanks obtained in step S4 are fed into the mold for hot pressing. The high temperature of the mold triggers the decomposition of ammonium bicarbonate to produce gas and the cross-linking and hardening of ammonium zirconium carbonate. The finished product is obtained by demolding.

7. The preparation method of the disposable tear-off waste tray paper base formula according to claim 6, characterized in that, The preparation method of the latent curing sizing agent is as follows: The film-forming substrate is dissolved in water to prepare a base solution. Ammonium bicarbonate is added to dissolve the substrate. The pH of the system is adjusted to 9.0-9.8 using a volatile alkali agent. Finally, ammonium zirconium carbonate solution is added while stirring and the viscosity is adjusted.

8. The preparation method of the disposable tear-off waste tray paper base formula according to claim 6, characterized in that, The preparation method of the micro-roughened oil-resistant coating liquid is as follows: Vinyl silicone oil was mixed with a micro-roughness modifier and dispersed under high shear, followed by the addition of hydrogen-containing silicone oil, inhibitor, and platinum catalyst solution, which were then mixed thoroughly and degassed.

9. The preparation method of the disposable tear-off waste tray paper base formula according to claim 6, characterized in that, The temperature control in steps S2 and S3 includes: In step S2, the drying temperature shall not exceed 95°C; In step S3, the pre-curing temperature is 105-115℃; The temperature control is used to prevent the ammonium bicarbonate in the adhesive layer from completely decomposing before hot pressing in step S5.

10. The preparation method of the disposable tear-off waste tray paper base formula according to claim 6, characterized in that, The temperature of the mold is 140-170℃, the molding pressure is 3.0-5.0MPa, and the holding time is 2-5 seconds.

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