Preparation process and application of environment-friendly release paper

Abstract

The invention relates to the technical field of release paper material preparation, and discloses an environment-friendly release paper preparation technology and application thereof.The environment-friendly release paper is prepared from an alkyl ketene dimer and sodium lignin sulfonate according to the ratio of 1: 1, the alkyl ketene dimer and the sodium lignin sulfonate cooperate to form an anchoring network, migration of a release agent can be effectively avoided, and it is ensured that release force is stable; a metal-free photocuring catalyst is matched with an LED-ultraviolet curing process to replace a heavy metal catalyst used in traditional thermocuring, the beneficial effect of thoroughly eliminating the risk of heavy metal residue in the release paper is achieved, meanwhile, the photocuring process has the advantages that compared with traditional thermocuring, energy consumption is reduced, VOC emission is avoided, heavy metal detection is avoided, and the service life of the release paper is prolonged. The environment-friendly superiority of the release paper is fully embodied, the release paper can be safely applied to the high-end field of food packaging and electronic device packaging, in addition, through the composite reinforcing filler containing the fly ash extract, resource utilization of industrial solid waste is achieved, and therefore the strength of the release paper is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of release paper material preparation technology, specifically to an environmentally friendly release paper preparation process and its application. Background Technology

[0002] Release paper, also known as anti-stick paper, is a type of paper that prevents prepreg from sticking together and protects it from contamination. It is widely used in self-adhesive labels, food packaging, electronic component assembly, and industrial die-cutting. With increasingly stringent environmental regulations (such as the EU RoHS directive's restrictions on heavy metals) and rising consumer demand for green packaging, the drawbacks of traditional release paper production processes are becoming increasingly apparent. On the one hand, traditional processes often use purely chemical additives and non-renewable fillers in pulp modification, and the release layer curing often employs thermal curing, requiring catalysts containing heavy metals such as tin and lead. This leads to the risk of heavy metal residues in the finished product, failing to meet the environmental requirements of food contact materials and high-end electronic packaging. On the other hand, release paper prepared using existing technologies often suffers from uneven release agent coating, easy migration and penetration leading to large fluctuations in release force, and insufficient paper strength. Furthermore, traditional processes consume significant water resources and have low waste recycling rates, making it difficult to achieve green manufacturing throughout the entire process. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an environmentally friendly release paper preparation process and its application. It has the advantages of no heavy metal residue throughout the entire process, stable and excellent release performance, high physical strength, and recyclability. It effectively solves the problems of heavy metal pollution risk, unstable performance due to easy migration of the release layer, and low utilization rate of industrial solid waste and water resources in traditional release paper.

[0004] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly release paper preparation process, comprising the following steps: Step 1: Raw material preparation and pretreatment: Prepare pulp substrate, composite reinforcing filler, environmentally friendly additives, environmentally friendly defoamer, metal-free photocuring catalyst, bio-based antistatic agent, preservative, sodium bicarbonate, hydroxyethyl cellulose and deionized water as raw materials according to the formula specific gravity. During pretreatment, the pulp substrate is crushed into powder. Step 2, Pulp Modification: Add pulp base powder to deionized water, stir and disperse to form a uniform pulp suspension, then add composite reinforcing filler and hydroxyethyl cellulose, and adjust the system temperature to carry out modification; Step 3, System Adjustment: Add environmentally friendly additives, bio-based antistatic agents, preservatives and sodium bicarbonate to the modified pulp suspension, stir and mix evenly, and then add environmentally friendly defoamer to eliminate bubbles; Step 4: Forming and papermaking: The adjusted pulp system is fed into the papermaking machine for forming and dewatering to form the paper base prototype; Step 5, Release Layer Curing: Mix water-based release agent, metal-free photocuring catalyst and deionized water in a set mass ratio to prepare a coating liquid, coat it evenly on the surface of the paper base prototype, and use LED-ultraviolet light for photocuring treatment to form a uniform release layer; Step 6, Post-processing and Finished Product: The coated and cured paper base is dried, calendered and cut. After passing inspection, the environmentally friendly release paper product is obtained.

[0005] Preferably, the raw materials and their proportions in step one are as follows: pulp substrate 58.0%-73.0%; composite reinforcing filler 8.0%-15.0%; environmentally friendly additives 2.5%-5.5%; environmentally friendly defoamer 0.1%-0.5%; metal-free photocuring catalyst 0.3%-0.5%; bio-based antistatic agent 0.4%-0.8%; preservative 0.1%-0.3%; water-based release agent 2.5%-7.5%; sodium bicarbonate 0.1%-0.5%; hydroxyethyl cellulose 0.5%-1.5%; and the remaining component is deionized water.

[0006] Preferably, the pulp base material is made by mixing FSC-certified bleached sulfate softwood pulp and bleached sulfate hardwood pulp in a mass ratio of 75:25 to 85:15, and incorporating 5%-15% of post-consumer recycled fiber by mass of the total pulp base material; the composite reinforcing filler is composed of modified bentonite, corn cationic starch and fly ash solid waste extract, wherein the mass ratio of modified bentonite to corn cationic starch is 3:1-5:1, and the calcium silicate in the fly ash solid waste extract accounts for 0.5%-2.0% of the total mass of the composite reinforcing filler.

[0007] Preferably, the environmentally friendly additive is composed of a 1:1 ratio of alkyl ketene dimer and sodium lignosulfonate; the water-based release agent is preferably a silicone-modified acrylate emulsion certified by the USDA for bio-based use; the environmentally friendly defoamer is polyether-modified silicone oil; the metal-free photocuring catalyst is an acylphosphine oxide photoinitiator; and the bio-based antistatic agent is a nonionic glycerol fatty acid ester.

[0008] Preferably, in step one, the raw material pretreatment involves crushing the pulp substrate into 80-100 mesh powder and mixing the composite reinforcing filler evenly for later use. The pulp modification process in step two: S1.1 First, add deionized water to the reactor and control the water temperature to 38-45℃. Then add pulp base powder and stir at a speed of 250-300r / min for 25-35min to form a uniform suspension. S1.2. Then add composite reinforcing filler and hydroxyethyl cellulose, adjust the stirring speed to 400-500 r / min, and continue stirring for 60-80 min to complete the pulp modification.

[0009] Preferably, the system adjustment in step three is as follows: S2.1 First, add the environmentally friendly additives, bio-based antistatic agents, and preservatives to the pulp suspension in sequence, and stir at 300-400 r / min for 20-30 min; S2.2 Add sodium bicarbonate to adjust the pH of the system to 7.0-7.5, and finally add environmentally friendly defoamer. Stir at a low speed of 30-50 r / min for 10-15 min.

[0010] Preferably, in step four, the forming process involves controlling the paper machine speed to 15-20 m / min, employing a vacuum dewatering process, a dewatering temperature of 50-55℃, a dewatering time of 13-19 min, and controlling the thickness of the paper base prototype to be between 0.08-0.25 mm.

[0011] Preferably, in step five, the release layer curing process involves: mixing an aqueous release agent with a metal-free photocurable catalyst and deionized water at a mass ratio of 100:0.5–2:10–30 to prepare a coating solution; uniformly applying the coating solution to the surface of the paper substrate using a doctor blade coating method, controlling the coating thickness to be 0.012–0.028 mm; and then placing the coated substrate into a UV curing machine at a UV light intensity of 350–400 mJ / cm². 2 Under these conditions, light curing is performed for 5-9 minutes to form a uniform release layer.

[0012] Preferably, the post-processing and finished product in step six are as follows: S3.1 First, put the paper base into the dryer, control the drying temperature at 60-70℃, the drying time at 20-30min, and control the moisture content of the paper base at 5%-7%; S3.2, Next, perform calendering treatment at a temperature of 70-80℃ and a pressure of 0.3-0.5MPa; S3.3 Finally, cut to the specified size according to requirements. After passing the inspection of appearance, release force and environmental protection indicators, package and put into storage. Cutting waste can be recycled and reused.

[0013] An application of an environmentally friendly release paper preparation process: the environmentally friendly release paper prepared according to the above process method is used in food packaging, electronic device packaging, industrial die-cutting and composite material fields.

[0014] Compared with existing technologies, this invention provides an environmentally friendly release paper preparation process and its application, which has the following beneficial effects: 1. This invention uses a metal-free photocuring catalyst (acylphosphine oxide photoinitiator) in conjunction with an LED-UV curing process to replace the tin- and lead-containing heavy metal catalysts used in traditional thermal curing. This achieves the beneficial effect of completely eliminating the risk of heavy metal residues in release paper. At the same time, this photocuring process consumes less energy than traditional thermal curing and has no VOC emissions. Combined with the verification of the examples, no heavy metals were detected, fully demonstrating the environmental advantages of this invention and enabling it to be safely applied in the high-end field of food packaging.

[0015] 2. This invention utilizes a composite reinforcing filler composed of modified bentonite, corn cationic starch, and fly ash solid waste extract (active calcium silicate), and takes advantage of the porous honeycomb structure of calcium silicate to achieve a significant improvement in the bonding strength and tensile strength of paper fibers. This design not only enhances the physical properties of paper but also enables the resource utilization of industrial solid waste (fly ash), ultimately reducing production costs.

[0016] 3. This invention utilizes an environmentally friendly additive composed of a 1:1 ratio of alkyl ketene dimer (AKD) and sodium lignosulfonate. The two work synergistically to form an anchoring network, achieving the beneficial effects of significantly improving the adsorption uniformity of water-based release agents on the paper substrate surface and effectively preventing release agent migration. Attached Figure Description

[0017] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0018] The technical solutions of 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.

[0019] Please see Figure 1 An environmentally friendly release paper preparation process includes the following steps: Step 1: Raw material preparation and pretreatment: Prepare pulp substrate, composite reinforcing filler, environmentally friendly additives, environmentally friendly defoamer, metal-free photocuring catalyst, bio-based antistatic agent, preservative, sodium bicarbonate, hydroxyethyl cellulose and deionized water as raw materials according to the formula specific gravity. Ensure that the purity of all raw materials meets the requirements of environmentally friendly preparation. During pretreatment, the pulp substrate is crushed into powder. Step 2, Pulp Modification: Add pulp base powder to deionized water, stir and disperse to form a uniform pulp suspension, then add composite reinforcing filler and hydroxyethyl cellulose, and adjust the system temperature to carry out modification; Step 3, System Adjustment: Add environmentally friendly additives, bio-based antistatic agents, preservatives and sodium bicarbonate to the modified pulp suspension, stir and mix evenly, and then add environmentally friendly defoamer to eliminate bubbles; Step 4: Forming and papermaking: The adjusted pulp system is fed into the papermaking machine for forming and dewatering to form the paper base prototype; Step 5, Release Layer Curing: Mix water-based release agent, metal-free photocuring catalyst and deionized water in a set mass ratio to prepare a coating liquid, coat it evenly on the surface of the paper base prototype, and use LED-ultraviolet light for photocuring treatment to form a uniform release layer; Step 6, Post-processing and Finished Product: The coated and cured paper base is dried, calendered and cut. After passing inspection, the environmentally friendly release paper product is obtained.

[0020] Specifically, the raw materials and their proportions in step one are as follows: pulp substrate 58.0%-73.0%; composite reinforcing filler 8.0%-15.0%; environmentally friendly additives 2.5%-5.5%; environmentally friendly defoamer 0.1%-0.5%; metal-free photocuring catalyst 0.3%-0.5%; bio-based antistatic agent 0.4%-0.8%; preservative 0.1%-0.3%; water-based release agent 2.5%-7.5%; sodium bicarbonate 0.1%-0.5%; hydroxyethyl cellulose (HEC) 0.5%-1.5%; and the remaining component is deionized water.

[0021] Specifically, the pulp base material is made by mixing FSC-certified bleached sulfate softwood pulp and bleached sulfate hardwood pulp in a mass ratio of 75:25 to 85:15, that is, softwood pulp accounts for 75%-85% and hardwood pulp accounts for 15%-25%, and post-consumer recycled (PCR) fiber is added, accounting for 5%-15% of the total mass of the pulp base material. This combination can support recycling while ensuring fiber strength. Specifically, the composite reinforcing filler consists of modified bentonite, corn cationic starch, and fly ash solid waste extract (the main component is active calcium silicate, with a calcium silicate content ≥86%, whiteness ≥86%, and specific surface area >150m²). 2 The composition consists of modified bentonite and corn cationic starch in a mass ratio of 3:1 to 5:1, while calcium silicate derived from fly ash solid waste accounts for 0.5% to 2.0% of the total mass of the composite reinforcing filler. This combination consists of natural mineral and plant-based materials. Its core advantage lies in using the porous honeycomb structure of calcium silicate to improve the bonding strength between the filler and the fiber, while realizing the resource utilization of industrial solid waste. When modified bentonite and corn starch are mixed, they have good compatibility due to their physical bonding mechanism, and ideal bonding strength can be obtained at different proportions. The introduction of fly ash forms a complementary relationship through a chemical bonding mechanism. Calcium silicate is used as a reinforcing component rather than the main filler, which differentiates it from existing technologies.

[0022] Specifically, the environmentally friendly additive consists of a 1:1 ratio of alkyl ketene dimer (AKD) and sodium lignosulfonate. The two work together to form an anchoring network, which can significantly improve the adsorption uniformity of water-based release agents on paper substrates and prevent migration. The water-based release agent is selected from one of acrylic monomers, silicone-modified acrylates or polyurethane curing agents, preferably silicone-modified acrylate emulsions that have passed USDA bio-based certification and are VOC-free. Its glass transition temperature is designed to be between -20°C and 10°C, taking into account both film-forming properties and release force. The environmentally friendly defoamer uses polyether-modified silicone oil, which meets FDA food contact standards; the metal-free photocuring catalyst uses acylphosphine oxide photoinitiators, which are compatible with low-energy LED UV curing processes, reducing curing energy consumption by more than 50% compared to traditional thermal curing, and eliminating the risk of heavy metal residues; the bio-based antistatic agent uses non-ionic glycerol fatty acid esters derived from vegetable oils, which are environmentally friendly; the natural preservative uses food-grade potassium sorbate; sodium bicarbonate acts as a pH stabilizer, maintaining the system's pH in a slightly neutral range of 6.5-7.5, thus preventing degradation of bio-based materials by strong alkalis; hydroxyethyl cellulose (HEC) is derived from renewable resources and effectively enhances coating stability.

[0023] Specifically, in step one, the raw material pretreatment involves crushing the pulp substrate into 80-100 mesh powder and mixing the composite reinforcing filler evenly for later use. The above pretreatment process ensures that the pulp substrate can be uniformly dispersed in deionized water and that the components of the composite reinforcing filler are fully integrated, laying the foundation for subsequent pulp modification, system stability and the uniformity of the final product performance. At the same time, it ensures that all raw materials meet environmental protection preparation standards and avoids pollution risks from the source.

[0024] Specifically, the pulp modification process in step two: S1.1 First, add deionized water to the reactor and control the water temperature to 38-45℃. Then add pulp base powder and stir at a speed of 250-300r / min for 25-35min to form a uniform suspension. S1.2 Add composite reinforcing filler and hydroxyethyl cellulose, adjust the stirring speed to 400-500 r / min, and continue stirring for 60-80 min to complete the pulp modification, improve the stiffness and binding force of the pulp. The whole process uses a water-based system with no harmful volatiles.

[0025] Through the above pulp modification process, the dispersibility and bonding properties of pulp fibers can be effectively improved. The composite reinforcing filler and hydroxyethyl cellulose work synergistically to significantly improve the stiffness, tensile strength and bonding strength with subsequent coating liquid of the pulp. At the same time, the design of the water-based system eliminates the generation of harmful volatile substances, which is in line with the concept of environmentally friendly preparation.

[0026] Specifically, in step three, the system is adjusted as follows: S2.1 First, add the environmentally friendly additives, bio-based antistatic agents, and preservatives to the pulp suspension in sequence, and stir at 300-400 r / min for 20-30 min to ensure that each component is evenly dispersed; S2.2 Add sodium bicarbonate to adjust the pH of the system to 7.0-7.5. Finally, add an environmentally friendly defoamer and stir at a low speed of 30-50 r / min for 10-15 min to completely eliminate bubbles in the system and avoid defects in subsequent molding. Since all additives are environmentally friendly, no pollutants are generated in this process.

[0027] Through the above system adjustment operations, the environmentally friendly additives can be evenly dispersed in the pulp suspension. The slightly neutral pH environment effectively protects the bio-based materials from degradation, while completely eliminating air bubbles in the system. This avoids defects such as pores and damage in the paper base after molding, ensuring the molding quality of the paper base prototype. Moreover, no pollutants are generated throughout the process, further enhancing the environmental friendliness of the process.

[0028] Specifically, in step four, the paper forming process involves controlling the paper machine speed to 15-20 m / min, using a vacuum dewatering process, a dewatering temperature of 50-55℃, and a dewatering time of 13-19 min to ensure that the thickness of the paper base is between 0.08-0.25 mm. The wastewater generated during the dewatering process can be recycled after simple filtration. This process meets environmental protection requirements and effectively reduces water waste.

[0029] Through the above-mentioned forming and papermaking operations, a paper base prototype with uniform thickness and dense structure can be obtained. The vacuum dehydration process is highly efficient and energy-saving, and the wastewater can be recycled, which greatly reduces water consumption. At the same time, the thickness of the paper base prototype is strictly controlled, providing a good base for subsequent release layer coating and curing, and ensuring the dimensional accuracy and performance stability of the final product.

[0030] Specifically, in step five, the release layer curing process involves mixing an aqueous release agent with a metal-free photocuring catalyst and deionized water at a mass ratio of 100:0.5–2:10–30 to prepare a coating solution. This solution is then evenly applied to the surface of the paper substrate using a doctor blade coating method, controlling the coating thickness to be 0.012–0.028 mm. After coating, the substrate is placed in a UV curing machine at a UV light intensity of 350–400 mJ / cm². 2 Under these conditions, a light-curing process is performed, with a curing time of 5-9 minutes, to form a uniform release layer. The absence of a metal-based light-curing catalyst effectively avoids heavy metal residues, resulting in no harmful gas emissions during the light-curing process. This makes it environmentally friendly and efficient, ensuring strong adhesion and excellent release performance of the release layer.

[0031] Specifically, in step six, post-processing and finished product: S3.1 First, send the paper base into the dryer, control the drying temperature at 60-70℃, and the drying time at 20-30 minutes to ensure that the moisture content of the paper base is controlled at 5%-7%; S3.2, Next, perform calendering treatment at a temperature of 70-80℃ and a pressure of 0.3-0.5MPa to improve the smoothness of the paper base surface; S3.3 Finally, the material is cut to the specified size according to requirements. After passing the inspection of appearance, release force and environmental protection indicators, it is packaged and stored. There are no harmful emissions during the drying process, and the cutting waste can be recycled and reused, achieving environmental protection throughout the entire process.

[0032] Through the above post-processing operations, the coated and cured paper base can be adjusted to the optimal state, the moisture content can be controlled to ensure that the paper base is not easily deformed or moldy, the calendering process improves the surface smoothness to meet the release requirements, and after cutting, it undergoes strict inspection to ensure that the finished product meets the usage standards of food packaging and other fields. At the same time, the cutting waste can be recycled and reused, realizing a closed-loop environmental protection process.

[0033] An application of an environmentally friendly release paper preparation process: the environmentally friendly release paper prepared according to the above process method is used in food packaging, electronic device packaging, industrial die-cutting and composite material fields.

[0034] The environmentally friendly release paper prepared by the above process was applied to the food packaging field (such as self-adhesive label backing paper), and commercially available ordinary release paper (containing organotin catalyst) was used as the main reference group to verify its release performance and heavy metal residue.

[0035] Example 1 This embodiment is prepared according to steps one through six. In step one, the components are as follows by weight: pulp substrate 65.0% (coniferous wood:broadleaf wood = 80:20, with 10% PCR fiber added); composite reinforcing filler 12.0% (modified bentonite:corn starch = 4:1, calcium silicate accounting for 1.5% of the total filler mass); environmentally friendly additives 4.0%; environmentally friendly defoamer 0.3%; metal-free photocuring catalyst 0.4%; bio-based antistatic agent 0.6%; preservative 0.2%; water-based release agent (organosilicon-modified acrylate emulsion) 5.0%; sodium bicarbonate 0.3%; hydroxyethyl cellulose 1.0%; and deionized water to 100%. In step five, the ratio of water-based release agent, metal-free photocuring catalyst, and deionized water is 100:1:20.

[0036] Example 2 This embodiment is basically the same as Example 1, except that the release layer curing formulation ratio was adjusted in step five to verify the effect of catalyst dosage on release performance. The ratio of water-based release agent, metal-free photocuring catalyst and deionized water is 100:0.5:10 (lower limit of catalyst, low curing rate).

[0037] Example 3 This embodiment is basically the same as embodiment 1, except that the release layer curing formula ratio is adjusted in step five. The ratio of water-based release agent, metal-free photocuring catalyst and deionized water is 100:2:30 (catalyst upper limit, high curing rate).

[0038] Comparative Example 1 This comparative example uses the preparation process of commercially available ordinary release paper as a reference. The pulp base material is 100% virgin wood pulp without the addition of PCR fiber; the reinforcing filler is only ordinary calcium carbonate, without the combination of calcium silicate and modified bentonite; the release layer curing adopts the traditional thermosetting process and uses a tin-containing catalyst (dibutyltin dilaurate).

[0039] Comparative Example 2 This comparative example serves as the control group for Example 1, used to verify the role of fly ash extract (calcium silicate) in the composite reinforcing filler. Its preparation process is basically the same as that of Example 1, except that in step two, fly ash solid waste extract (calcium silicate) was not added to the composite reinforcing filler, and the mass deficiency was filled by modified bentonite.

[0040] Comparative Example 3 This comparative example serves as the control group for Example 1, used to verify the synergistic effect of AKD and sodium lignosulfonate in the environmentally friendly additive. Its preparation process is basically the same as that of Example 1, except that only alkyl ketene dimer (AKD) is added in step three, and sodium lignosulfonate is not added.

[0041] The application effects of the examples and comparative examples are compared, and the specific data are shown in Table 1 below: Table 1 Comparison of the performance of environmentally friendly release paper

[0042] From Table 1, we can obtain: (1) Environmental protection: Compared with Comparative Example 1 which uses a tin-containing catalyst, no heavy metal residues were detected in any of the embodiments of the present invention, which fully demonstrates the core environmental protection value of metal-free photocuring catalysts. At the same time, Example 1 achieves the resource utilization of industrial solid waste (fly ash) and post-consumer recycled fiber (PCR) while ensuring high performance.

[0043] (2) Relationship between release performance and formulation: Example 1 uses a medium catalyst ratio to obtain the best balance between release force and residual adhesion rate (12.5g, 92.5%), with the best overall performance; Example 2 (low catalyst ratio) has a high release force and a low residual adhesion rate due to insufficient curing and crosslinking; Example 3 (high catalyst ratio) has a fast curing speed and the lowest release force, but the excessively high crosslinking density has a slight impact on the residual adhesion rate; Comparative Example 3 lacks sodium lignosulfonate for synergistic anchoring, resulting in severe migration of the release agent, a sharp increase in release force and a significant decrease in residual adhesion rate, which proves the key role of the two in forming an "anchoring network" in environmentally friendly additives.

[0044] (3) Physical strength and antistatic properties: The tensile strength of Examples 1-3 is better than that of Comparative Examples 1 and 2. This is due to the synergistic reinforcing effect of modified bentonite, corn starch and porous calcium silicate in the composite reinforcing filler, as well as the stabilizing effect of hydroxyethyl cellulose. Comparative Example 2 has a lower fiber bonding strength and is significantly lower than that of Example 1 due to the lack of porous honeycomb structure of calcium silicate. Examples with added bio-based antistatic agents and Comparative Examples 2 and 3 have significantly lower surface resistivity than the commercially available product without added bio-based antistatic agents (Comparative Example 1), which proves that they have good antistatic properties and are suitable for packaging electronic devices.

[0045] In summary, this invention successfully prepared a high-performance release paper that is environmentally friendly and recyclable throughout the entire process by using a metal-free photocuring system, a composite reinforcing filler containing industrial solid waste (fly ash extract), and bio-based functional additives. The data in Table 1 confirms that this process (especially Example 1) not only completely eliminates the risk of heavy metal residue in traditional processes, but also outperforms or significantly outperforms commercially available ordinary products and the control group in key indicators such as release force, residual adhesion rate, and tensile strength. It solves the quality pain point caused by release agent migration, making it extremely valuable for high-end applications such as food packaging and electronic device packaging.

[0046] 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. An environmentally friendly release paper preparation process, characterized in that, Includes the following steps: Step 1: Raw material preparation and pretreatment: Prepare the following raw materials according to the formula: pulp substrate, composite reinforcing filler, environmentally friendly additives, environmentally friendly defoamer, metal-free photocuring catalyst, bio-based antistatic agent, preservative, water-based release agent, sodium bicarbonate, hydroxyethyl cellulose and deionized water. During pretreatment, the pulp substrate is crushed into powder. Step 2, Pulp Modification: Add pulp base powder to deionized water, stir and disperse to form a uniform pulp suspension, then add composite reinforcing filler and hydroxyethyl cellulose, and adjust the system temperature to carry out modification; Step 3, System Adjustment: Add environmentally friendly additives, bio-based antistatic agents, preservatives and sodium bicarbonate to the modified pulp suspension, stir and mix evenly, and then add environmentally friendly defoamer to eliminate bubbles; Step 4: Forming and papermaking: The adjusted pulp system is fed into the papermaking machine for forming and dewatering to form the paper base prototype; Step 5, Release Layer Curing: Mix water-based release agent, metal-free photocuring catalyst and deionized water in a set mass ratio to prepare a coating liquid, coat it evenly on the surface of the paper base prototype, and use LED-ultraviolet light for photocuring treatment to form a uniform release layer; Step 6, Post-processing and Finished Product: The coated and cured paper base is dried, calendered and cut. After passing the inspection, the environmentally friendly release paper product is obtained.

2. The environmentally friendly release paper preparation process according to claim 1, characterized in that: The raw materials and their proportions in step one are as follows: pulp substrate 58.0%-73.0%; composite reinforcing filler 8.0%-15.0%; environmentally friendly additives 2.5%-5.5%; environmentally friendly defoamer 0.1%-0.5%; metal-free photocuring catalyst 0.3%-0.5%; bio-based antistatic agent 0.4%-0.8%; preservative 0.1%-0.3%; water-based release agent 2.5%-7.5%; sodium bicarbonate 0.1%-0.5%; hydroxyethyl cellulose 0.5%-1.5%; and the remaining component is deionized water.

3. The environmentally friendly release paper preparation process according to claim 2, characterized in that: The pulp base material is made by mixing FSC-certified bleached sulfate softwood pulp and bleached sulfate hardwood pulp in a mass ratio of 75:25 to 85:15, and incorporating 5%-15% of post-consumer recycled fiber by mass of the total pulp base material. The composite reinforcing filler is composed of modified bentonite, corn cationic starch and fly ash solid waste extract, wherein the mass ratio of modified bentonite to corn cationic starch is 3:1-5:1, and the calcium silicate in the fly ash solid waste extract accounts for 0.5%-2.0% of the total mass of the composite reinforcing filler.

4. The environmentally friendly release paper preparation process according to claim 2, characterized in that: The environmentally friendly additives consist of a 1:1 ratio of alkyl ketene dimer and sodium lignosulfonate; the water-based release agent is selected from one of acrylic monomers, silicone-modified acrylates, or polyurethane curing agents; the environmentally friendly defoamer is polyether-modified silicone oil; the metal-free photocuring catalyst is an acylphosphine oxide photoinitiator; and the bio-based antistatic agent is a nonionic glycerol fatty acid ester.

5. The environmentally friendly release paper preparation process according to claim 1, characterized in that, In step one, the raw material pretreatment involves crushing the pulp substrate into 80-100 mesh powder and mixing the composite reinforcing filler evenly for later use. The pulp modification process in step two: S1.1 First, add deionized water to the reactor and control the water temperature to 38-45℃. Then add pulp base powder and stir at a speed of 250-300r / min for 25-35min to form a uniform suspension. S1.

2. Then add composite reinforcing filler and hydroxyethyl cellulose, adjust the stirring speed to 400-500 r / min, and continue stirring for 60-80 min to complete the pulp modification.

6. The environmentally friendly release paper preparation process according to claim 1, characterized in that: The system adjustment in step three: S2.1 First, add the environmentally friendly additives, bio-based antistatic agents, and preservatives to the pulp suspension in sequence, and stir at 300-400 r / min for 20-30 min; S2.2 Add sodium bicarbonate to adjust the pH of the system to 7.0-7.5, and finally add environmentally friendly defoamer. Stir at a low speed of 30-50 r / min for 10-15 min.

7. The environmentally friendly release paper preparation process according to claim 1, characterized in that: In step four, the paper forming process involves controlling the paper machine speed to 15-20 m / min, using a vacuum dewatering process, a dewatering temperature of 50-55℃, a dewatering time of 13-19 min, and controlling the thickness of the paper base prototype to be between 0.08-0.25 mm.

8. The environmentally friendly release paper preparation process according to claim 1, characterized in that: In step five, the release layer curing process involves mixing an aqueous release agent with a metal-free photocuring catalyst and deionized water at a mass ratio of 100:0.5–2:10–30 to prepare a coating solution. This solution is then uniformly applied to the surface of the paper substrate using a doctor blade coating method, controlling the coating thickness to be 0.012–0.028 mm. After coating, the substrate is placed in a UV curing machine at a UV light intensity of 350–400 mJ / cm². 2 Under these conditions, light curing is performed for 5-9 minutes to form a uniform release layer.

9. The environmentally friendly release paper preparation process according to claim 1, characterized in that: Post-processing and finished product in step six: S3.1 First, put the paper base into the dryer, control the drying temperature at 60-70℃, the drying time at 20-30min, and control the moisture content of the paper base at 5%-7%; S3.2, Next, perform calendering treatment at a temperature of 70-80℃ and a pressure of 0.3-0.5MPa; S3.3 Finally, cut to the specified size according to requirements. After passing the inspection of appearance, release force and environmental protection indicators, package and put into storage. Cutting waste can be recycled and reused.

10. The application of an environmentally friendly release paper preparation process, characterized in that, The environmentally friendly release paper prepared by the process described in claim 1 can be used in food packaging, electronic device packaging, industrial die-cutting and composite materials.

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