A light and thin solvent-free silicone oil release paper manufacturing process

Abstract

The application discloses a kind of light and thin solvent-free silicone oil release paper manufacturing process, belong to release paper manufacturing technical field, package following steps: paper selection, primer, drying primer, spraying release agent, scanning and scraping release layer, flatten release layer, drying release layer, water recovery, release paper winding, select low, thin base paper of grammage, then lower coating dry weight is used to primer to base paper is carried out primer and drying is formed to form film layer to obtain intermediate paper, when spraying release agent, atomizer will release agent atomization into particle and be sprayed to the surface of film layer of intermediate paper, let release agent particle be evenly attached to the surface of film layer of intermediate paper, then through scraper and two flatten rollers destroy the surface tension of release agent particle, let all release agent particles be fused together, the particle size of release agent particle after atomization is smaller, can reduce the thickness of release layer, then release layer is dried, water recovery is obtained after getting light and thin release paper of low grammage, low thickness.

Description

Technical Field

[0001] The invention relates to the technical field of release paper manufacturing, and in particular to a manufacturing process of light and thin solvent-free silicone oil release paper. Background Art

[0002] Release paper is a smooth coated paper with a layer of laminating layer on the base paper and then coated with a layer of release agent. When used, it can be peeled off with a certain force, which plays a role in protection and prevention of adhesion. As release paper can be applied in more and more fields, the demand for release paper is increasing and the market competition is becoming more and more fierce. Therefore, various release paper manufacturers have improved the performance of release paper or reduced production costs by improving the production process. Improving the production process of release paper requires optimizing the corresponding production equipment at the same time to make the entire production process more rational.

[0003] Patent document 1: A flame-retardant release paper and its production process (publication number: CN104250945B publication date: 2016-08-24), discloses a flame-retardant release paper and its production process, the release paper is composed of base paper and a flame-retardant primer and a silicone oil layer coated on its outer surface in sequence. The production process is to use an in-machine double-sided film coating machine to evenly coat a high-solid content flame-retardant primer coating with an inorganic flame retardant on both sides of the base paper, after drying, dehydration and shaping treatment, appropriate paper surface calendering treatment, and then apply a solvent-free silicone oil solution on the surface of the above-mentioned primer paper, and then heat cure, regain moisture at room temperature, and then finish, slit, and rewind into a finished product.

[0004] Patent document 2: A silicone oil coating machine for release paper (publication number: CN214782920U, publication date: 2021-11-19), discloses a silicone oil coating machine for release paper, including: a coating frame, a horizontally arranged paint collecting trough is installed at the bottom of the coating frame, a slide rail is provided on the end edge of the paint collecting trough, a first movable mounting seat is installed on the slide rail, a metering roller and a cleaning roller are installed side by side on the first movable mounting seat, a feeding roller is installed on the left side of the metering roller, a feeding nozzle is installed on the upper right side of the metering roller, a film transfer roller is installed on the upper left of the feeding roller, a vertically arranged second movable mounting seat is installed on the left side of the coating frame, the coating roller is installed on the second movable mounting seat and is located directly above the film transfer roller, the coating pressure roller is installed directly above the coating roller, and a coating pressure roller adjustment cylinder is installed above the coating pressure roller.

[0005] The release paper production process in Patent Document 1 uses solvent-free silicone oil as the release layer of the release paper. Compared with solvent-based silicone oil, solvent-free silicone oil has the advantages of being more environmentally friendly, more stable, more lubricating, more resistant to high temperatures, and lower cost. It can improve the performance of the release paper while reducing the production cost of the release paper. However, the coating amount of the solvent-free silicone oil in this process is 0.8-1.0gsm, and the large coating amount of the release agent leads to a high production cost of the release paper. Currently, in the production process of release paper, a silicone oil coating machine such as that in Patent Document 2 is usually used to coat the release agent on the laminating layer or the primer layer. The silicone oil coating machine adopts a six-roller film transfer structure to apply the release agent. Although the film transfer method can evenly apply the release agent on the laminating layer or the primer layer, in order to ensure that the release paper does not slip or fall off during the production process, a release agent with a higher viscosity needs to be used. At the same time, a high-viscosity release agent tends to form a thicker release layer during the coating process, thereby increasing the thickness of the release paper. A thicker release layer means that more release agent needs to be applied, which makes it difficult to reduce the production cost of the release paper. At the same time, a thicker release layer will reduce the softness of the release paper.

[0006] Therefore, there is still room for improvement in the release agent coating process and equipment of release paper. However, most of the steps in the release paper production process are not independent of each other. While improving the release agent coating process of release paper, it is also necessary to adapt other processes to make the entire release paper production process more reasonable. Summary of the Invention

[0007] In view of the technical defects existing in the background technology, the present invention proposes a production process for a thin and light solvent-free silicone oil release paper, which solves the above technical problems and meets the actual needs. The specific technical solution is as follows:

[0008] A process for producing a thin solvent-free silicone oil release paper, characterized in that it comprises the following steps:

[0009] S1. Select paper with a weight of 13-28gsm and a thickness of 30-50μm;

[0010] S2. Primer: The base paper is unwound through the unwinding device and unwound to the primer device for primer operation. The primer device evenly coats a layer of primer on the glossy surface of the base paper.

[0011] S3 drying primer, the base paper coated with primer after leaving the primer equipment is then transferred to the glue drying equipment for drying operation, after drying the base paper surface primer solidifies to form a coating layer to obtain the middle paper;

[0012] S4. Spraying a release agent, conveying the intermediate paper to the atomized coating device for coating the release agent, the atomized coating device atomizes and uniformly sprays the release agent on the surface of the intermediate paper, and a plurality of atomized release agent particles adhere to the surface of the intermediate paper to form a release layer;

[0013] S5. Scrape the release layer, the intermediate paper after forming the release layer continues to be conveyed in the atomized coating device and the release layer is scraped by the scraper to destroy the surface tension of the release agent;

[0014] S6. Flatten the release layer, the release layer of the intermediate paper is scraped and continues to be conveyed in the atomized coating device, and the release layer is rolled to be uniform by two flattening rollers;

[0015] S7. Dry the release layer, after the release layer is rolled, it is conveyed to the floating drying device for drying operation, and the release layer after drying is solidified on the surface of the intermediate paper to obtain a release paper, the release paper has a grammage of 15-30 gsm;

[0016] S8. Water replenishment and humidification, the solidified release paper is subjected to non-contact water replenishment and humidification;

[0017] S9. Roll the release paper, the release paper after water replenishment and humidification is rolled by the rolling device;

[0018] The atomizer is provided outside the atomized coating device, a plurality of spray nozzles are provided on the outside of the atomizer, each of the spray nozzles faces one side of the intermediate paper, and the atomizer, the scraper and the two flattening rollers are arranged in sequence along the conveying direction of the intermediate paper in the atomized coating device.

[0019] As a further technical solution of the present application, the grammage tolerance of the base paper is ±1%-2%.

[0020] As a further technical solution of the present application, the bottom glue is a PVA glue and latex mixed solution, and the coating dry weight of the bottom glue is 1-1.5 gsm.

[0021] As a further technical solution of the present application, the working temperature of the glue drying device is 60-90°C.

[0022] As a further technical solution of the present application, the release agent uses a solvent-free silicone oil, and the coating dry weight of the release agent is 0.3-0.5 gsm.

[0023] As a further technical solution of the present application, a surfactant is added to the release agent, the surfactant uses polyoxyethylene ether, and the addition amount of the surfactant is 3-5 g / L.

[0024] As a further technical solution of the present application, the speed of the atomized coating device conveying the intermediate paper is 1-2 m / s.

[0025] As a further technical solution of the present invention, the operating frequency of the atomizer is 2-2.5 MHz and the output power is 100-150 W.

[0026] As a further technical solution of the present invention, the suspension drying equipment includes a first silicon oven, a second silicon oven, a third silicon oven, a fourth silicon oven, a fifth silicon oven, a sixth silicon oven, a seventh silicon oven, and an eighth silicon oven arranged in sequence, totaling eight relatively independent and serially connected suspension silicon oven assemblies.

[0027] As a further technical solution of the present invention, the operating temperature of the first silicon oven is 80-100°C, the operating temperature of the second silicon oven is 95-115°C, the operating temperature of the third silicon oven is 110-130°C, the operating temperature of the fourth silicon oven is 125-140°C, the operating temperature of the fifth silicon oven is 120-130°C, the operating temperature of the sixth silicon oven is 110-125°C, the operating temperature of the seventh silicon oven is 100-115°C, and the operating temperature of the eighth silicon oven is 90-100°C.

[0028] The beneficial effects of the present invention are:

[0029] The present invention uses an atomizer to atomize the release agent into micron-sized particles and then sprays them onto the surface of the coating layer of the intermediate paper, allowing the release agent particles to evenly adhere to the surface of the coating layer of the intermediate paper. Subsequently, a scraper and two flattening rollers are used to destroy the surface tension of the release agent particles, and the release agent particles are fused together under the intermolecular interaction force. After atomization, the release agent particles adhere to the surface of the coating layer and form a release layer with a thickness reaching the micron level. At the same time, a base paper with low grammage and thickness and a low dry amount of primer coating are selected, and finally a light and thin release paper with low grammage and thickness is produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a process flow chart for the production of thin, solvent-free silicone release paper.

[0031] Figure 2 The diagram is a structural diagram of an atomizing coating device for the production process of a thin, solvent-free silicone oil release paper.

[0032] Among them: atomizing coating equipment 1, atomizer 2, spray nozzle 3, scraper 4, flattening roller 5. DETAILED DESCRIPTION

[0033] The following describes the implementation of the present invention in conjunction with the accompanying drawings and relevant embodiments. The implementation of the present invention is not limited to the following embodiments, and the present invention relates to the relevant necessary components in this technical field, which should be regarded as the common knowledge in this technical field and can be known and mastered by technical personnel in this technical field.

[0034] like Figure 1 As shown, the present invention discloses a process for producing a thin and light solvent-free silicone oil release paper, comprising the following steps:

[0035] S1. Select paper with a weight of 13-28gsm and a thickness of 30-50μm;

[0036] S2. Primer: The base paper is unwound through the unwinding device and unwound to the primer device for primer operation. The primer device evenly coats a layer of primer on the glossy surface of the base paper.

[0037] S3 drying primer, the base paper coated with primer after leaving the primer equipment is then transferred to the glue drying equipment for drying operation, after drying the base paper surface primer solidifies to form a coating layer to obtain the middle paper;

[0038] S4. Spraying the release agent: The intermediate paper is transferred to an atomizing coating device for coating. The atomizing coating device atomizes the release agent and evenly sprays it onto the surface of the laminated layer of the intermediate paper. Several atomized release agent particles adhere to the surface of the laminated layer of the intermediate paper to form a release layer.

[0039] S5. Scrape the release layer, and the intermediate paper after forming the release layer continues to be transported in the atomizing coating device and the surface tension of the release agent is destroyed by scraping the release layer;

[0040] S6. Flatten the release layer. After scraping the release layer of the middle paper, continue to transfer it in the atomizing coating equipment and pass through two flattening rollers to roll the release layer until it is evenly distributed.

[0041] S7 drying release layer, the release layer is rolled and then transferred to a suspension drying device for drying. After drying, the release layer is cured on the surface of the intermediate paper to obtain a release paper having a gram weight of 15-30gsm.

[0042] S8. Rehydration and rewetting: non-contact rehydration and rewetting of the cured release paper;

[0043] S9. Rewind the release paper. After replenishing water and rewetting, the release paper is rewound by the rewinding equipment.

[0044] It should be pointed out that after completing the S1-S7 processes, the release paper obtained can repeat the relevant steps of S2-S7 on the side not coated with the release agent, and then perform the operations of steps S8 and S9 to form double-sided release paper, which can meet more usage and processing requirements.

[0045] At the same time, in order to cooperate with the production process of release paper, several release paper manufacturing equipment compatible with the production process are also required, including an unwinding device arranged in sequence according to the release paper manufacturing process, a primer coating device connected to the unwinding device and used to primer the smooth surface of the base paper, a glue drying device connected to the primer coating device and used to heat and dry the intermediate paper after primer coating, an atomizing coating device connected to the glue drying device and used to spray, smooth and press silicone oil on the dried intermediate paper, a suspension drying device connected to the atomizing coating device and used to dry the release layer of the intermediate paper, a steam humidification device or a centrifugal humidification device connected to the suspension drying device and used to replenish water and rehumidify the release paper, and a winding device.

[0046] The base paper selected in step S1 has a grammage of 13-28 gsm and a thickness of 25-50 μm. It is a relatively light and thin paper. This paper has good softness due to its lightness and thinness, thereby ensuring that the release paper produced is sufficiently light and thin and has good softness. The grammage tolerance of the base paper is ±1%-2%. The lower grammage tolerance can ensure that the weight and thickness of the base paper are more stable and consistent, thereby allowing subsequent processes to proceed more smoothly and the resulting release paper product to be more stable and consistent.

[0047] When implementing step S2, the unwinding equipment includes a placement rack and a paper cutting knife, and the unwinding equipment adopts a double-station fully automatic non-stop unwinding equipment. In the process of unwinding the base paper to the primer coating equipment, the unwinding equipment is also provided with an unwinding traction equipment, a dust removal equipment and a process correction equipment arranged in sequence, so that the base paper remains straight and enters the primer coating equipment for primer coating. The primer coating equipment includes a traction device, so that the base paper is coated with primer through the glue coating anilox roller and the glue coating silicon pressure roller. The primer coating equipment can be suitable for white latex or PVA glue. After the primer coating is completed, the base paper is immediately transferred to the glue drying equipment for baking.

[0048] Among them, an online glue quantity detection device is installed between the primer coating equipment and the glue drying equipment to monitor the primer coating amount in real time, so as to facilitate the adjustment and warning of abnormal primer coating process at any time, so that the primer coating process of the primer coating equipment is stable and controlled, and the quality of the release paper primer coating is improved; during the transmission process of the base paper, the tension roller is used to make real-time compensation for the base paper according to the fluctuation situation during the transmission process, thereby ensuring the stability of the tension during the primer coating and avoiding fluctuations in the primer coating amount caused by tension fluctuations.

[0049] When implementing step S3, in this embodiment, the glue drying equipment includes a first glue oven, a second glue oven, a third glue oven, a fourth glue oven, and a fifth glue oven arranged in sequence, a total of five relatively independent and serially connected glue drying box assemblies. The glue drying equipment preferably adopts a suspended oven. The suspended oven has the advantages of high drying efficiency and uniform drying. It can dry the base glue quickly and evenly and form a coating layer, which can avoid problems such as bubbling, delamination, and warping of the coating layer.

[0050] Among them, the working temperature of the first glue drying box is 60-75℃, the working temperature of the second glue drying box is 70-85℃, the working temperature of the third glue drying box is 80-90℃, the working temperature of the fourth glue drying box is 75-85℃, and the working temperature of the fifth glue drying box is 65-80℃. The working temperatures of the five glue drying boxes gradually increase and then decrease in sequence. The temperature is increased in a step-by-step manner, so that the base glue gradually absorbs heat during the transmission of the base paper and the temperature is increased steadily, so that the moisture, solvent and volatile substances in the base glue gradually evaporate. It can also avoid problems such as bubbling, delamination and warping of the coating layer. The base glue on the surface of the base paper is dried in the glue drying equipment to form a coating layer and obtain the intermediate paper.

[0051] After the base paper is coated with primer, it must be immediately placed in the glue drying oven for drying. Otherwise, the moisture in the primer will penetrate into the paper, causing the fibers of the base paper to absorb water, swell and deform. Ultimately, the base paper will be severely deformed after drying in the glue drying oven, making it impossible to proceed with subsequent processes and resulting in the product being scrapped.

[0052] When implementing steps S4-S6, in this embodiment, a correction mechanism, a tension isolation mechanism, and a cooling mechanism are provided between the glue drying device and the atomizing coating device. The dried intermediate paper passes through the above mechanisms in sequence and then enters the atomizing coating device for spraying the release agent.

[0053] like Figure 2 As shown, an atomizer 2 is provided in the atomizing coating device 1, and a plurality of spray nozzles 3 are provided on the outside of the atomizer 2, each spray nozzle 3 faces one side of the coating layer of the intermediate paper, the atomizer 2, the scraper 4, and the two flattening rollers 5 are arranged in sequence along the transmission direction of the intermediate paper in the atomizing coating device; when the intermediate paper enters the atomizing coating device 1, the coating layer faces upward, the atomizer 2 and the scraper 4 are both located directly above the intermediate paper, the plurality of spray nozzles 3 are located at the bottom of the atomizer 2 and arranged along the width direction of the intermediate paper, each spray nozzle 3 is tilted toward the side where the intermediate paper enters the atomizing coating device 1, the top of the scraper 4 abuts against the top surface of the intermediate paper, the flattening roller 5 preferably adopts a rubber roller with hydrophobic modification, the surface flatness of the flattening roller 5 is 0.3-0.5μm, the two flattening rollers 5 are distributed up and down, and a gap matching the thickness of the base paper is provided between the two flattening rollers 5, and the intermediate paper leaves the atomizing coating device after passing through the gap.

[0054] The atomizer 2 of the present invention preferably adopts an ultrasonic atomizer. When the intermediate paper is transferred to the atomizing coating device 1, the atomizer 2 atomizes the release agent into microparticles and sprays them evenly onto the surface of the coating layer through a plurality of spray nozzles 3. The release agent microparticles contact the coating layer and adhere to the surface of the coating layer. A plurality of release agent microparticles fuse with each other on the surface of the coating layer under the intermolecular force, thereby causing the release agent to diffuse and infiltrate the surface of the coating layer. As the intermediate paper is transferred, the release agent attached to the surface of the coating layer will contact the bottom end of the scraper 4. Some of the release agent microparticles that have not been fused will break the surface tension under the contact of the scraper 4, thereby causing most of the release agent to be dispersed. The release agent particles are fused together, and then the two flattening rollers 5 roll the middle paper. The two flattening rollers 5 rotate in opposite directions to roll the middle paper while conveying it. The contact between the flattening rollers 5 and the release agent will further destroy the surface tension of the release agent. The hydrophobicity of the surface of the flattening roller 5 can prevent the release agent from sticking to the surface of the flattening roller. After being rolled by the two flattening rollers 5, all the release agents will be fused together, and after being rolled by the two flattening rollers 5, the release agent on the surface of the coating layer will be more evenly distributed. After being rolled by the two flattening rollers 5, the middle paper enters the suspension drying equipment to dry the release agent.

[0055] Furthermore, currently, high-speed mixers, sand mills, and high-pressure homogenizers can all atomize silicone oil into microparticles, and these three devices can atomize silicone oil into microparticles below 0.2 μm. In actual process tests, it was found that when any of the three devices was used to atomize the solvent-free silicone oil and then sprayed onto the surface of the coating layer and combined with a flattening roller 5 with a flatness of 0.1-0.2 μm, the thickness of the release layer after solidification was about 0.2 μm. However, under the influence of the surface tension of the solvent-free silicone oil and the surface flatness of the coating layer, the surface of the coating layer could not be completely atomized. The release paper is covered with solvent-free silicone oil, which leads to defects in the peeling performance of the release paper. If the amount of surfactant added is increased until the solvent-free silicone oil can evenly cover the surface of the coating layer, the release paper produced will have too low peeling force at room temperature and will be difficult to stick to the surface of sticky objects such as tape. Therefore, this release paper is only suitable for surface protection and other fields. However, the coating layer thickness of this release paper is relatively low. When used in the field of surface protection, the surface release layer is easily scratched and loses its surface protection effect. Therefore, the application of this release paper in the field of surface protection is not very meaningful.

[0056] It can be seen from this that although other means can be used to allow solvent-free silicone oil to form a thinner release layer on the surface of the coating layer, due to the properties of the silicone oil itself and the application scenarios of the release paper, the release paper with a thinner release layer currently does not have a better application prospect. Moreover, the efficiency of atomizing silicone oil by a high-speed mixer, a sand mill, and a high-pressure homogenizer is lower than that of an ultrasonic atomizer. Although the amount of silicone oil used is reduced, the use of the above three devices will increase the energy consumption of the release paper manufacturing process. Therefore, the atomizer 2 of the present invention preferably uses an ultrasonic atomizer.

[0057] When implementing step S7, the suspension drying equipment includes a first silicon oven, a second silicon oven, a third silicon oven, a fourth silicon oven, a fifth silicon oven, a sixth silicon oven, a seventh silicon oven, and an eighth silicon oven, which are arranged in sequence, a total of eight relatively independent and serially connected suspension silicon oven assemblies. Each suspension silicon oven is provided with two rollers identical to the flattening roller 5, and the intermediate paper runs through the gap between each two rollers. The suspension oven has the advantages of high drying efficiency and uniform drying. It can quickly and evenly dry the release agent and form a release layer, which can avoid problems such as cracking and delamination of the release layer. The use of rollers for rolling during the release agent drying process can allow the release layer to better adhere to the surface of the coating layer. In addition, the surfactant will volatilize during the release agent drying process, causing the viscosity of the release agent to increase. This process may cause the surface of the release layer after drying to be uneven or even cracked. The use of rollers for rolling during the release agent drying process can further flatten the release layer before the release agent is cured, thereby avoiding the problem of unevenness or even cracking of the release layer after drying and curing.

[0058] The operating temperature of the first silicon oven is 80-100°C, the second silicon oven is 95-115°C, the third silicon oven is 110-130°C, the fourth silicon oven is 125-140°C, the fifth silicon oven is 120-130°C, the sixth silicon oven is 110-125°C, the seventh silicon oven is 100-115°C, and the eighth silicon oven is 90-100°C. The operating temperatures of the eight suspended silicon ovens gradually increase and then decrease. The eight suspended silicon ovens can also maintain a uniform speed of conveying the intermediate paper while extending the drying time. The stepped temperature increase allows the release agent to gradually absorb heat during the conveying of the intermediate paper, resulting in a steady temperature increase and gradual volatilization of the surfactant in the release agent. This can also prevent the release layer from becoming uneven or even cracking after drying and curing. The release agent on the surface of the coating layer is dried in the suspended drying equipment to form a release layer and obtain release paper.

[0059] Prior to this, the release agent was mostly coated by the film transfer method when making release paper. This method can evenly coat the release agent and the coated release layer can be applied to substrates of various materials. However, in order to ensure that the release paper does not slip or fall off during the production process, a release agent with a higher viscosity needs to be used. At the same time, a high-viscosity release agent tends to form a thicker release layer during the coating process, thereby increasing the thickness of the release paper. A thicker release layer means that more release agent needs to be coated, resulting in difficulty in reducing the production cost of the release paper. At the same time, a thicker release layer will also affect the softness of the release paper. The current process of coating the release agent by the film transfer method has reached a bottleneck or limit state where it is difficult to reduce the thickness of the release layer. However, based on market demand and competition direction, it is urgent to improve the coating process of the release agent to improve the product competitiveness of the release paper.

[0060] In the present invention, according to steps S4-S7, the atomizer 2 atomizes the release agent into a number of particles with a diameter of 0.5-1 μm and attaches them to the surface of the coating layer. The release agents are fused and diffused by the scraper 4 and rolled by two flattening rollers 5. The thickness of the release agent attached to the surface of the coating layer is 0.5-1 μm. Then the release agent is dried in the suspension drying equipment and rolled by the rolling roller. Finally, the release layer thickness of the finished release paper is 0.5-0.8 μm. The traditional process of applying the release agent by film transfer has a release layer thickness of 1-3 μm. The present invention achieves the purpose of reducing the amount of release agent applied to reduce production costs. At the same time, the produced release paper has better softness.

[0061] The atomizer 2 of the present invention atomizes the release agent into microparticles and uniformly adheres them to the surface of the coating layer, thereby reducing the thickness of the release agent on the surface of the coating layer, thereby reducing the amount of release agent used without affecting the formation of a release layer with a release effect on the release paper. As the thickness of the release layer becomes thinner and the amount of release agent used decreases, the softness of the release paper is improved and the production cost of the release paper is reduced.

[0062] In order to ensure the quality of the final product, step S8 is executed. After the release paper is dried by the suspension drying equipment, it enters the cooling equipment for cooling. After being dried by the suspension drying equipment, the release paper becomes brittle and the coated surface curls severely. It is easy to wrinkle, turn over, and break during the transmission process. Therefore, after cooling, the release paper needs to be rehumidified by a non-contact steam rehumidification box or centrifugal humidification equipment to increase the moisture content of the paper to improve the flatness of the paper, thereby ensuring that the release paper can smoothly perform the winding operation of step S9. The release paper cannot be completely soaked by replenishing water once. It must be replenished with water in small amounts and multiple times to restore the humidity of the release paper to the level before the base paper is coated, especially the lower grammage base paper used in the present invention. Therefore, the release paper of the present invention needs to add a rehydration and rehumidification process, and the non-contact rehydration and rehumidification can improve the uniformity of rehydration.

[0063] The performance parameters of the release paper finally produced by the present invention are as follows: gram weight 15-30 gsm, dry coating amount of release agent 0.3-0.5 gsm, peel strength at room temperature 0.1-0.3 N / 25 mm, peel strength less than 0.6 N / 25 mm after aging at 70°C for 20 h, and residual adhesion rate >90%. It can be seen that even if the coating amount of release agent is reduced, the release paper product still has good performance and the softness of the release paper is improved.

[0064] As one of the preferred embodiments of the present invention, the primer is a mixture of PVA glue and latex, and the dry coating weight of the primer is 1-1.5 gsm.

[0065] The PVA glue can improve the water resistance, aging resistance and release performance of the release paper, the latex can make the primer more evenly and firmly adhere to the surface of the base paper, thereby avoiding the delamination and other problems of the release paper, and the coating amount of the primer needs to be adaptively adjusted according to the grammage of the base paper, preferably 1.5 gsm for the base paper with low grammage, which can ensure the strength of the finished release paper, and the coating dry amount of the primer is reduced for the base paper with high grammage.

[0066] As one of the preferred embodiments of the present application, the release agent is a solvent-free silicone oil, and the coating dry amount of the release agent is 0.3-0.5 gsm.

[0067] Compared with the solvent type silicone oil, the solvent-free silicone oil has the advantages of being more environmentally friendly, better stability, more lubrication, more high temperature resistance and lower cost, which can improve the performance of the release paper while reducing the production cost of the release paper, the release paper produced by the present application reduces the coating dry amount of the release agent to 0.3-0.5 gsm, preferably 0.3 gsm, which can ensure that the release paper has good softness and further reduce the production cost of the release paper.

[0068] As one of the preferred embodiments of the present application, a surfactant is added to the release agent, the surfactant is polyoxyethylene ether, and the addition amount of the surfactant is 3-5 g / L.

[0069] The polyoxyethylene ether of the present application preferably uses one of green and environmentally friendly propylene glycol polyoxyethylene ether or block polyoxyethylene ether as the surfactant of the release agent, which can reduce the viscosity and surface tension of the release agent and improve its dispersibility, permeability and other properties, so that the release agent can be more easily atomized into finer particles, and the release agent particles can more easily fuse and diffuse with each other after adhering to the surface of the coating layer. The higher volatility of the polyoxyethylene ether causes a certain volatilization during the drying of the release agent, thereby reducing its impact on the release performance of the release paper. Although increasing the addition amount of the surfactant can further reduce the viscosity and surface tension of the release agent and improve its dispersibility, permeability and other properties, based on the cost and release performance of the finished release paper, the addition amount of the surfactant is determined as 3-5 g / L after a large number of process test verifications and technical scheme demonstrations, thereby producing a light and thin release paper with a grammage of 15-30 gsm, a release agent coating dry amount of 0.3-0.5 gsm, a room temperature release force of 0.1-0.3 N / 25 mm, a release force of less than 0.6 N / 25 mm after aging at 70 DEG C for 20 hours, and a residual sticking rate of > 90%.

[0070] Among them, the amount of surfactant added needs to be adaptively adjusted according to the viscosity of each batch of release agent, so as to adjust the viscosity of the release agent to an appropriate range. During the drying process of the release layer, not all surfactants will evaporate. The residual surfactant in the release layer will reduce the peeling force of the release paper. Therefore, the peeling force of the release paper can be changed by appropriately adjusting the amount of surfactant added.

[0071] As one of the preferred embodiments of the present invention, the speed of the atomizing coating device 1 in transmitting the intermediate paper is 1-2 m / s, the operating frequency of the atomizer 2 is 2-2.5 MHz, and the output power is 100-150 W.

[0072] The present invention controls the speed of the atomized coating device 1 transmitting the intermediate paper in order to allow the release agent particles to be evenly attached to the surface of the coating layer. If the speed of the atomized coating device 1 transmitting the intermediate paper is too fast, the release agent particles will not be able to completely cover the surface of the coating layer. If the speed of the atomized coating device 1 transmitting the intermediate paper is too slow, too many release agent particles will be attached to the surface of the coating layer and the thickness of the release layer will increase. According to the high viscosity of the solvent-free silicone oil, the atomizer 2 adopts an operating frequency of 2-2.5MHz and an output power of 100-150W to transfer the solvent-free silicone oil. It is smoothly atomized into particles with a diameter of 0.5-1μm. When the internal temperature of the atomizer 2 is low at the beginning of operation, a higher operating frequency and output power are required to atomize the solvent-free silicone oil, and the operating frequency and output power of the atomizer 2 need to be adaptively adjusted according to the viscosity of each batch of solvent-free silicone oil. After a large number of process tests, the speed of the atomizing coating equipment 1 transmitting the intermediate paper and the operating frequency and output power of the atomizer 2 are set within a suitable range, so that the process of the atomizing coating equipment 1 coating the release agent meets the process requirements for making release paper.

[0073] In summary, after a large number of process tests and technical solutions were verified, the present invention optimized the process of coating release agent on release paper, and finally achieved the process goals of low release agent coating amount and thin release paper. The key lies in how to make the release agent adhere evenly and firmly to the surface of the coating layer after atomization, and meet the requirements of production and use. Therefore, in the selection, processing and subsequent steps of raw materials, different and targeted changes need to be made from the existing release paper production process, and finally the release paper production process of the present invention is obtained.

[0074] The above description is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for producing a thin, light, solvent-free silicone release paper, characterized by: The following steps are included: S1. Select paper with a weight of 13-28gsm and a thickness of 30-50μm; S2. Primer: The base paper is unwound through the unwinding device and unwound to the primer device for primer operation. The primer device evenly coats a layer of primer on the glossy surface of the base paper. S3 drying primer, the base paper coated with primer after leaving the primer equipment is then transferred to the glue drying equipment for drying operation, after drying the base paper surface primer solidifies to form a coating layer to obtain the middle paper; S4. Spraying the release agent: The intermediate paper is transferred to an atomizing coating device for coating. The atomizing coating device atomizes the release agent and evenly sprays it onto the surface of the laminated layer of the intermediate paper. Several atomized release agent particles adhere to the surface of the laminated layer of the intermediate paper to form a release layer. The release agent is solvent-free silicone oil, and the dry coating weight of the release agent is 0.3-0.5gsm; A surfactant is added to the release agent, wherein the surfactant is polyoxyethylene ether, and the addition amount of the surfactant is 3-5 g / L; S5. Scrape the release layer, and the intermediate paper after forming the release layer continues to be transported in the atomizing coating device and the surface tension of the release agent is destroyed by scraping the release layer; S6. Flatten the release layer. After scraping the release layer of the middle paper, it continues to be transferred in the atomizing coating equipment and rolled by two flattening rollers to make the release layer uniform; S7 drying release layer, the release layer is rolled and then transferred to a suspension drying device for drying. After drying, the release layer is cured on the surface of the intermediate paper to obtain a release paper having a gram weight of 15-30gsm. S8. Rehydration and rewetting: non-contact rehydration and rewetting of the cured release paper; S9. Rewinding the release paper. After rehydration and rewetting, the release paper is rewound by a rewinding device. The atomizing coating device is provided with an atomizer, and a plurality of spray nozzles are provided on the outside of the atomizer, each of the spray nozzles is directed toward the coating layer of the intermediate paper, and the atomizer, scraper, and two flattening rollers are arranged in sequence along the conveying direction of the intermediate paper in the atomizing coating device; When the intermediate paper enters the atomizing coating equipment, the coating layer faces upward. The atomizer and scraper are both located directly above the intermediate paper. Several spray nozzles are located at the bottom of the atomizer and arranged along the width of the intermediate paper. Each spray nozzle is tilted toward the side where the intermediate paper enters the atomizing coating equipment. The top of the scraper contacts the top surface of the intermediate paper. The flattening roller uses a rubber roller that has been modified for hydrophobicity. The surface flatness of the flattening roller is 0.3-0.5μm. The two flattening rollers are distributed vertically, and a gap matching the thickness of the base paper is set between the two flattening rollers. The intermediate paper passes through the gap and leaves the atomizing coating equipment. The atomizer uses an ultrasonic atomizer, which atomizes the release agent into particles with a diameter of 0.5-1μm and attaches them to the surface of the coating layer. The scraper makes the release agents merge and diffuse with each other and after being rolled by two flattening rollers, the thickness of the release agent attached to the surface of the coating layer is 0.5-1μm.

2. The process for producing the thin solvent-free silicone release paper according to claim 1, characterized in that: The tolerance of the base paper weight is ±1%-2%.

3. The process for producing the thin solvent-free silicone release paper according to claim 1, characterized in that: The dry coating weight of the primer is 1-1.5 gsm.

4. The process for producing the thin and light solvent-free silicone oil release paper according to claim 1, characterized in that: The working temperature of the glue drying equipment is 60-90°C.

5. The process for producing the thin and light solvent-free silicone oil release paper according to claim 1, characterized in that: The speed at which the atomizing coating device transmits the intermediate paper is 1-2 m / s.

6. The process for producing the thin and light solvent-free silicone oil release paper according to claim 1, characterized in that: The operating frequency of the atomizer is 2-2.5 MHz, and the output power is 100-150 W.

7. The process for producing the thin and light solvent-free silicone oil release paper according to claim 1, characterized in that: The suspension drying equipment includes a first silicon oven, a second silicon oven, a third silicon oven, a fourth silicon oven, a fifth silicon oven, a sixth silicon oven, a seventh silicon oven, and an eighth silicon oven arranged in sequence, a total of eight relatively independent and serially connected suspension silicon oven components.

8. The process for producing the thin and light solvent-free silicone oil release paper according to claim 7, characterized in that: The operating temperature of the first silicon oven is 80-100°C, the operating temperature of the second silicon oven is 95-115°C, the operating temperature of the third silicon oven is 110-130°C, the operating temperature of the fourth silicon oven is 125-140°C, the operating temperature of the fifth silicon oven is 120-130°C, the operating temperature of the sixth silicon oven is 110-125°C, the operating temperature of the seventh silicon oven is 100-115°C, and the operating temperature of the eighth silicon oven is 90-100°C.

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