Release paper with composite multilayer structure and manufacturing process of release paper

Abstract

The invention relates to the technical field of release paper, in particular to release paper with a composite multilayer structure, which comprises a base material paper layer, a first bonding layer arranged at the top of the base material paper layer, a first surface functional layer arranged at the top of the first bonding layer, and a second bonding layer arranged at the bottom of the base material paper layer, and a second surface functional layer is arranged at the bottom of the second bonding layer. According to the release paper with the composite multi-layer structure and the manufacturing process of the release paper, the base material paper layer is impregnated and modified to form the microscopic expansion holes, and the interlayer physical occlusion and binding force are strengthened in cooperation with the negative pressure adsorption spraying film; a PMP-PA66 composite system is subjected to high-temperature lamination to form a compact barrier structure, water vapor and oxygen permeation is effectively blocked, a temperature-sensitive microcapsule containing a PMMA wall material and a stripping regulator core material is utilized to realize adaptive intelligent regulation of stripping force temperature, and meanwhile, the bonding resin is grafted and modified to form a bonding enhanced structure, so that the stripping strength is improved. And the interlayer bonding stability and the environment-resistant characteristic are improved.

Description

Technical Field

[0001] This invention relates to the field of release paper technology, specifically to a composite multilayer release paper and its manufacturing process. Background Technology

[0002] Release paper, also known as release paper or anti-stick paper, is a functional paper whose surface has been specially treated to have low surface energy and anti-stick properties. Its core feature is that it can be easily peeled off after contact with adhesive substances without leaving any adhesive residue. It has excellent value in protecting adhesive surfaces, maintaining adhesive stability, and serving as a carrier substrate for adhesive products, facilitating subsequent processing such as die-cutting, lamination, and printing.

[0003] A search revealed a release paper manufacturing process and the release paper produced therein, disclosed in Chinese Patent Publication No. CN111218850A. This release paper manufacturing process involves two coating processes on the smooth surface of the paper, forming an adhesive layer and a release agent layer sequentially. Then, a back coating is applied to the rough surface of the paper to form an anti-curling layer. The process layout is tailored to the characteristics of the paper, adhesive, silicone oil, and anti-curling adhesive, with optimized coating and drying processes to achieve a thinner, more uniform, smoother, and more resilient release paper. The back coating on the rough surface forms an anti-curling layer, and steam humidification further enhances the release paper's toughness, preventing edge curling and preventing the release paper from folding up.

[0004] However, the release paper designed by this release paper manufacturing process only achieves basic anti-sticking and anti-rolling functions. Its structure is relatively simple and its functions are relatively limited, and it cannot effectively improve the interlayer bonding force. Based on the existing technical shortcomings, a release paper with a composite multilayer structure and its manufacturing process are proposed. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a composite multilayer release paper and its manufacturing process, which has the advantages of enhancing functional properties through a multilayer composite structure and improving the bonding strength between layers through a modification process. This solves the problems of simple structure, weak functionality, and weak interlayer bonding strength in release paper produced by existing release paper manufacturing processes.

[0007] (II) Technical Solution

[0008] To achieve the above-mentioned goal of enhancing functional characteristics through a multi-layer composite structure and improving the bonding force between layers through modification processes, the present invention provides the following technical solution: a release paper with a composite multi-layer structure, comprising a substrate paper layer, a first bonding layer disposed on the top of the substrate paper layer, a first surface functional layer disposed on the top of the first bonding layer, a second bonding layer disposed on the bottom of the substrate paper layer, and a second surface functional layer disposed on the bottom of the second bonding layer.

[0009] Preferably, the first bonding layer is a PMP and PA66 composite system, which includes an outer PMP structure and an inner PA66 structure, forming a dense barrier coating structure. The first surface functional layer is a silicone oil release coating containing temperature-sensitive microcapsules, with the outer wall material of the microcapsules being PMMA and the inner core material being a release modifier.

[0010] Preferably, the second bonding layer is an adhesive-reinforced structure composed of an adhesive resin, and the second surface functional layer is a polyvinyl alcohol coating, incorporating a filler layer into the polyvinyl alcohol coating.

[0011] A process for manufacturing release paper with a composite multilayer structure includes the following steps: S1. The substrate paper layer is impregnated in an impregnation tank and then dried to form a micro-expansion pore structure in the inner core, thus obtaining a modified substrate; S2. The composite coating material is simultaneously extruded on both the upper and lower surfaces of the substrate paper layer using a dual coating head-synchronous coating method, and after cooling and molding, the first bonding layer and the second bonding layer are obtained. S3. The temperature-sensitive microcapsules are uniformly dispersed in a release agent, coated onto a barrier coating structure layer, and dried and cured to form the first surface functional layer. S4. Apply a PVA coating to the adhesive reinforcement layer, and after curing, form a second surface functional layer to obtain a release paper composite structure.

[0012] Preferably, in step S1, the modifier in the impregnation tank is a solvent-free high-temperature resistant resin, and in step S2, the dual-coating head-simultaneous coating method includes: 1) A high-temperature coating head of a coating machine is used to coat the top surface of the substrate paper layer with PMP-PA66 composite coating at 280~300℃ to form a high-barrier coating structure. 2) Apply an adhesive resin coating at 210~230℃ to the bottom surface of the substrate paper layer using a medium-temperature coating head of a coating machine. Modify the adhesive resin by incorporating maleic anhydride-grafted polyolefin to form an adhesive reinforcement layer structure.

[0013] Preferably, the film is heated and melted at the coating outlet of the coating machine, and the molten film is adsorbed onto the expansion pore structure of the base paper by negative pressure control to enhance the bonding force.

[0014] Preferably, in step S3, a filler layer is incorporated into the polyvinyl alcohol coating, including one of conductive particles, antistatic masterbatch, and fluorescent marking material.

[0015] Preferably, after forming the release paper composite layer in step S4, ultraviolet laser technology is used to laser ablate the preset area of ​​the composite layer to form a micron-level air-permeable pore array. Ultraviolet irradiation technology ensures that the active components in the release layer and adhesive layer undergo in-situ cross-linking reaction to improve temperature resistance and interlayer bonding.

[0016] Compared with the prior art, the present invention provides a composite multilayer release paper and its manufacturing process, which has the following beneficial effects: 1. The composite multilayer release paper and its manufacturing process achieve a five-layer functional synergy structure by using a base paper layer, a double bonding layer, and a double surface functional layer. Each layer functions synergistically. The base paper layer is impregnated and modified to form micro-expansion pores. Combined with negative pressure adsorption coating, the physical interlocking and bonding force between layers are strengthened.

[0017] 2. The release paper with this composite multilayer structure and its manufacturing process form a dense barrier structure through high-temperature lamination of the PMP-PA66 composite system, which effectively blocks the penetration of water vapor and oxygen. It also utilizes temperature-sensitive microcapsules containing PMMA wall material and peel modifier core material to achieve intelligent adjustment of peel force temperature adaptability. At the same time, the adhesive resin is grafted and modified to form an adhesive reinforcement structure, which improves the interlayer adhesion stability and environmental resistance.

[0018] 3. The composite multilayer release paper and its manufacturing process form a nanoscale air-permeable pore array through ultraviolet laser ablation and achieve in-situ cross-linking reaction by ultraviolet irradiation, which simultaneously improves air permeability, temperature resistance and mechanical properties, and ensures the stability of the overall performance of the release paper. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the composite multilayer release paper structure of the present invention; Figure 2 This is a flowchart of the release paper manufacturing process of the present invention.

[0020] In the figure: 1. Substrate paper layer; 2. First bonding layer; 3. First surface functional layer; 4. Second bonding layer; 5. Second surface functional layer. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and 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. Example 1

[0022] In this embodiment, the base paper is impregnated and modified with solvent-free bisphenol A type epoxy resin to form a uniform micro-expansion pore structure in the core of the substrate paper layer, thereby improving the adhesion to the subsequent bonding layer. The specific steps are as follows: 1) Start the impregnation equipment and preheat it to 45~50℃. Add solvent-free high-temperature resistant resin and start the circulating filtration system to run for 30 minutes to remove impurities from the resin. 2) Adjust the paper force controller to 15N, install the paper roll onto the unwinding frame, and pull the paper through the guide roller, impregnation tank and extrusion roller in sequence at a speed of 6~8m / min. The impregnation time is 35~40s and the impregnation pressure is 0.12~0.15MPa. 3) Control the length of the impregnation path by arranging guide rollers, apply uniform pressure by pressure rollers to ensure resin penetration, control the amount of resin adhering to the extrusion rollers, and recycle excess resin. 4) The impregnated base paper is drawn into a three-stage drying oven and dried sequentially according to preset temperature and air speed parameters to ensure resin curing and the formation of micro-expansion pores in the paper core. The drying parameters are as follows: First stage drying: temperature 80~85℃, wind speed 2.5m / s, drying time 2min; Second stage drying: temperature 110~125℃, wind speed 3.0m / s, drying time 3min; The third stage of drying: temperature is 130℃, wind speed is 3.5m / s, and drying time is 1~2min; 5) After drying, the paper is cooled to room temperature by a cooling roller and then wound up to obtain the modified substrate paper layer. The winding tension is controlled at 20N to avoid damaging the expansion pore structure. The modified substrate index is as follows: the moisture content is controlled at 5%±0.5%, the micro-expansion pore diameter is 10-20μm, and the porosity is 18%±2%. Example 2

[0023] In this embodiment, according to asynchronous coating technology, a high-barrier first bonding layer and an adhesive-enhanced second bonding layer are formed on the upper and lower surfaces of the modified substrate, respectively, to ensure strong interlayer bonding. The specific steps include: 1) Add the PMP-PA66 mixture, ethylene-vinyl acetate copolymer (EVA), and maleic anhydride grafted polyolefin to the hoppers of two extruders respectively, start the drying device, control the temperature at 120~130℃, and dry for 4 hours. 2) Start the dual-station coating unit, raise the temperature of the high-temperature coating head to 295°C, raise the temperature of the medium-temperature coating head to 225°C, and raise the temperature of the extruder to the corresponding process temperature; The temperatures of each zone of the extruder used for processing the first bonding layer are as follows: Zone 1 of the barrel 240~250℃, Zone 2 260~270℃, Zone 3 280~290℃, and Die head 295℃. The temperatures of each zone of the extruder for processing the second bonding layer are as follows: Zone 1 of the barrel 180~190℃, Zone 2 200~210℃, Zone 3 215~220℃, and the die head 225℃, and the temperature is maintained for 30 minutes. 3) Install the modified substrate paper layer onto the unwinding rack of the coating machine, adjust the tension to 25N, start the substrate running system, and set the speed to 11~13m / min; 4) When the substrate reaches the coating area, start two extruders. The high-temperature coating head extrudes the PMP-PA66 composite coating onto the top layer of the substrate, and the medium-temperature coating head extrudes the adhesive resin coating onto the bottom layer of the substrate. At the same time, turn on the negative pressure adsorption device and set the vacuum degree to 0.07~0.10MPa to adsorb the molten film into the micro-expansion pores on the surface of the substrate. 5) After coating, the composite substrate is cooled and formed by a cooling roller group at a controlled temperature of 15~20℃. The thickness of the two bonding layers is monitored in real time by a thickness detector. After cooling, the winding tension is controlled at 30N to obtain a preliminary product with the first bonding layer and the second bonding layer. Example 3

[0024] In this embodiment, the specific steps for forming a temperature-responsive first surface functional layer by quantitative coating with a release agent include: 1) Weigh out hydroxyl silicone oil, methyltriacetoxysilane, dibutyltin dilaurate and ethyl acetate according to the formula ratio of 95% hydroxyl silicone oil, 3% curing agent, 0.5% catalyst and 1.5% diluent, add them to the disperser and stir at 2000 r / min for 10 min to mix evenly. 2) Slowly add the temperature-sensitive microcapsules to the mixture in 1), adjust to 8000 r / min, disperse at 25~30℃ for 30 min, take a sample every 5 min, and use a laser particle size analyzer to check the uniformity of microcapsule dispersion. After dispersion, use a viscometer to check the viscosity of the system to ensure that the viscosity range is 800 mPa•s±50 mPa•s. If the viscosity is too high, add an appropriate amount of ethyl acetate to adjust it. 3) Install the product with the first bonding layer onto the unwinding rack of the quantitative coating machine, adjust the tension to 20N, set the coating speed to 8~10m / min and the doctor blade gap to 0.12mm, and start the coating machine to evenly coat the well dispersed release agent system onto the surface of the first bonding layer. 4) Place the coated product into a hot air circulating drying oven and dry and cure it at 110℃ and 2.0m / s for 2~3 minutes to ensure that the release agent is completely cured and the microcapsules are evenly attached to the surface. After curing, cool to room temperature to obtain a product with the first surface functional layer. Example 4

[0025] In this embodiment, the adhesive resin is modified by grafting maleic anhydride onto polyolefin to improve the adhesion strength between the second bonding layer and the substrate paper layer and the second surface functional layer. The specific steps include: 1) Weigh out EVA resin, maleic anhydride, dicumyl peroxide and triallyl isocyanurate according to the formula ratio of 93% base resin, 4% grafting monomer, 0.8% initiator and 2.2% grafting agent, add them to a high-speed mixer, set the speed to 800~1000 r / min and mix for 15 min to ensure uniform mixing of raw materials. 2) Start the twin-screw extruder and heat it up according to the preset temperature parameters. After the temperature of each zone reaches the set value, keep it at the temperature for 20 minutes to ensure the equipment temperature. The temperature of each zone of the barrel is: Zone 1 120~130℃, Zone 2 150~165℃, Zone 3 170~175℃, Zone 4 185℃, Zone 5 190℃ and the die head 185℃. 3) The mixed raw materials are fed into the twin-screw extruder at a uniform speed of 25 kg / h and a screw speed of 450~600 r / min. The raw materials undergo a melt grafting reaction under the shearing and mixing action of the screw, and the volatiles are discharged through the exhaust section. The vacuum degree is controlled at 0.08~0.10 MPa. 4) The grafted and modified resin is extruded through the die head to form a strip melt, which is cooled to below 60°C at 25°C in a water cooling tank. The cooled resin strip is then fed into a granulator, and the pellet length is controlled to be 2.5mm ± 0.3mm to obtain grafted and modified adhesive resin granules. 5) After sampling, the grafting rate was detected using a Fourier transform infrared spectrometer, and the MFR was detected using a melt flow rate meter. Example 5

[0026] In this embodiment, a uniform array of micron-sized air-permeable pores is formed in a predetermined area of ​​the composite layer by ultraviolet laser ablation to improve the air permeability of the release paper. The specific steps include: 1) Start the UV laser marking machine and high-precision motion platform. After preheating for 30 minutes, calibrate the laser power to 20W using a laser power meter. Install the product after the second surface functional layer coating onto the motion platform. Determine the processing area using a vision positioning system, exclude the 5cm edge area, and set the opening area to 40% of the surface. 2) Input the micro-hole parameters into the equipment control system, including the hole diameter of 60μm, the hole spacing of 250μm, and the regular hexagonal arrangement, and the laser processing parameters, including the pulse frequency of 50kHz and the scanning speed of 600mm / s, and generate the processing path; 3) Start the motion platform. The composite release paper moves at a constant speed of 5~7m / min. The laser ablates the composite layer according to the preset path to form a micropore array. 4) During the processing, samples are taken every 1m, and the aperture, spacing and depth of the micropores are observed with a microscope. If there is a deviation in aperture, the laser power is adjusted. At this time, the power is reduced by 1W when the deviation is +5μm, and the power is increased by 1W when the deviation is -5μm. 5) After processing, the composite release paper is dusted by blowing with compressed air, and the blowing pressure is controlled at 0.3MPa. Example 6

[0027] In this embodiment, ultraviolet irradiation technology is used to induce in-situ crosslinking reactions of the active components in the release layer and adhesive layer, thereby improving the temperature resistance and interlayer bonding strength of the release paper. The specific steps include: 1) Start the ultraviolet irradiator and the environmental temperature and humidity control system, adjust the ambient temperature to 60℃ and the humidity to 40%, preheat for 20 minutes, and use an irradiance intensity detector to calibrate the irradiance intensity of the ultraviolet irradiator to ensure that it is 90mW / cm² and its wavelength is 254nm. 2) Place the composite release paper formed by laser micropores into a conveyor belt system, adjust the conveyor belt speed to 10~12m / min, and ensure that the composite release paper stays in the irradiation area for 45s. 3) Start the conveyor belt and pass the composite release paper through the ultraviolet irradiation area at a uniform speed to receive ultraviolet irradiation with a wavelength of 254nm. The siloxane active groups in the release layer and the grafted resin active groups in the adhesive layer undergo an in-situ cross-linking reaction. 4) After irradiation, samples are taken and detected using an infrared spectrometer. The crosslinking degree of the release layer and adhesive layer is detected by comparing the intensity of the Si-O-Si characteristic peaks before and after crosslinking. If the crosslinking degree of the release layer is <90%, the irradiation time is extended by 5s; if the crosslinking degree of the adhesive layer is <85%, the irradiation intensity is increased by 5mW / cm². The crosslinked composite release paper is naturally cooled to room temperature and then wound up and stored with a winding tension of 25N. Example 7

[0028] In this embodiment, the performance tests for composite release paper include: 1. Peel test 1) Lay the first surface functional layer (release layer) of the composite release paper with the standard pressure-sensitive tape (acrylic pressure-sensitive tape, 0.1mm thick), and roll it back and forth twice with a 2kg roller at a speed of 300mm / min to ensure a tight bond; 2) Install the bonded sample into the electronic universal tensile testing machine, set the peel angle to 180°, the tensile speed to 270~300mm / min, and test the peel force between the release layer and the pressure-sensitive adhesive tape; 3) Test each sample 3 times and take the average value as the final peel strength.

[0029] 2. High temperature resistance test 1) Place the sample in a constant temperature oven, set the test temperature to 160~180℃, and keep it at that temperature for 24 hours; 2) After the heat preservation is completed, turn off the oven and allow it to cool naturally to room temperature before removing the sample; 3) Observe whether the sample appearance is deformed, delaminated, or yellowed, and measure the sample size change rate (length and width directions).

[0030] 3. Bending tensile strength test 1) Install the sample onto the bending test machine, set the bending angle to 180°, the bending speed to 10 times / min, and the number of bends to 100; 2) After bending, install the sample into an electronic universal tensile testing machine, set the tensile speed to 45~50mm / min, and test the tensile strength and elongation at break of the sample. 3) Test each sample twice and take the average value.

[0031] 4. Anti-curling test 1) Place the sample flat on a horizontal platform in a constant temperature and humidity chamber with a temperature of 23℃±2℃ and a humidity of 50%±5%. Press the center of the sample with a 100g weight and leave it for 2 hours. 2) Remove the weights and continue to place the sample in a constant temperature and humidity environment for 24 hours. Use a laser rangefinder to measure the curling height of the four corners of the sample, that is, the vertical distance between the curled corners and the table surface.

[0032] The beneficial effects of the present invention are: the composite multilayer release paper and its manufacturing process achieve a five-layer functional synergistic structure by using a base paper layer, a double bonding layer, and a double surface functional layer. Each layer functions synergistically. The base paper layer is impregnated and modified to form micro-expansion pores. Combined with negative pressure adsorption coating, the physical interlocking and bonding force between layers are strengthened. The PMP-PA66 composite system forms a dense barrier structure through high-temperature lamination, effectively blocking the penetration of water vapor and oxygen. The temperature-sensitive microcapsules containing PMMA wall material and peel modifier core material enable intelligent adjustment of peel force based on temperature. At the same time, the adhesive resin is grafted and modified to form an adhesive reinforcement structure, improving the interlayer adhesion stability and environmental resistance. The release paper is formed by forming a nanoscale air-permeable pore array through ultraviolet laser ablation and then using ultraviolet irradiation to achieve an in-situ cross-linking reaction, which simultaneously improves air permeability, temperature resistance and mechanical properties, ensuring the overall stability of the release paper.

[0033] 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 composite multilayer release paper, comprising a substrate paper layer (1), characterized in that, A first bonding layer (2) is provided on the top of the substrate paper layer (1), a first surface functional layer (3) is provided on the top of the first bonding layer (2), a second bonding layer (4) is provided on the bottom of the substrate paper layer (1), and a second surface functional layer (5) is provided on the bottom of the second bonding layer (4).

2. The composite multilayer release paper according to claim 1, characterized in that, The first bonding layer (2) is a PMP and PA66 composite system, which includes a PMP structure on the outer layer and a PA66 structure on the inner layer, and forms a dense barrier coating structure. The first surface functional layer (3) is a silicone oil release coating containing temperature-sensitive microcapsules, with PMMA as the outer wall material of the microcapsules and a release modifier as the inner core material.

3. The release paper with a composite multilayer structure according to claim 1, characterized in that, The second bonding layer (4) is an adhesive reinforcement structure composed of adhesive resin, and the second surface functional layer (5) is a polyvinyl alcohol coating with a filler layer incorporated into the polyvinyl alcohol coating.

4. A process for manufacturing release paper with a composite multilayer structure, characterized in that, Includes the following steps: S1. The substrate paper layer (1) is impregnated in an impregnation tank and then dried to form a micro-expansion pore structure in the inner core, thereby obtaining a modified substrate; S2. The composite coating material is extruded simultaneously on both the upper and lower surfaces of the substrate paper layer (1) using a double coating head-synchronous coating method, and after cooling and molding, the first bonding layer (2) and the second bonding layer (4) are obtained. S3. The temperature-sensitive microcapsules are uniformly dispersed in the release agent, coated on the barrier coating structure layer, and dried and cured to form the first surface functional layer (3). S4. Apply a PVA coating to the adhesive reinforcement layer and cure it to form a second surface functional layer (5) to obtain a release paper composite structure.

5. The composite multilayer release paper and its manufacturing process according to claim 4, characterized in that, In step S1, the modifier in the impregnation tank is a solvent-free, high-temperature resistant resin. In step S2, the dual-coating head-simultaneous coating method includes the following steps: 1) A high-temperature coating head of a coating machine is used to coat PMP-PA66 composite coating at 280~300℃ on the top surface of the substrate paper layer (1) to form a high-barrier coating structure. 2) Apply a medium-temperature coating head of a coating machine to the bottom surface of the substrate paper layer (1) at 210~230℃ to coat an adhesive resin coating. The adhesive resin is modified by grafting maleic anhydride onto a grafted polyolefin to form an adhesive reinforcement layer structure.

6. The composite multilayer release paper and its manufacturing process according to claim 5, characterized in that, The film is heated and melted at the coating outlet of the coating machine, and the molten film is adsorbed onto the expansion pore structure of the base paper by negative pressure control to enhance the bonding force.

7. The composite multilayer release paper and its manufacturing process according to claim 4, characterized in that, In step S3, a filler layer is incorporated into the polyvinyl alcohol coating, including one of conductive particles, antistatic masterbatch, and fluorescent marking material.

8. The composite multilayer release paper and its manufacturing process according to claim 4, characterized in that, After the release paper composite layer is formed in step S4, the preset area of ​​the composite layer is laser-ablated using ultraviolet laser technology to form a micron-level air-permeable pore array. Ultraviolet irradiation technology is used to ensure that the active components in the release layer and adhesive layer undergo in-situ cross-linking reaction to improve temperature resistance and interlayer bonding.

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