A method for manufacturing a low-grammage solventless silicone oil release paper

Abstract

The application discloses a kind of low gram weight's solvent-free silicone oil release paper manufacturing method, belong to release paper manufacturing technical field, including the steps of papermaking, primer, drying primer, coating release agent, drying release agent, water recovery, release paper is wound, the application is based on thermoplastic fiber silk heating to certain temperature can be repeatedly reshaped and the characteristics of setting, the process of papermaking is stretched by the speed difference of conveying before paper forming to obtain low gram weight base paper, then primer is carried out to base paper, after coating release agent, low gram weight release paper is obtained, since thermoplastic fiber silk has higher strength and toughness than plant fiber after solidification, the release paper of the application has better mechanical strength than the release paper of same gram weight or even higher gram weight, the release paper of the application can reduce the addition amount of pulp in the process of papermaking, realize higher environmental protection, and the gram weight and thickness of release paper are lower, can reduce the cost of release paper transportation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of release paper manufacturing, in particular to a manufacturing method of low-grammage solvent-free silicone oil release paper. BACKGROUND

[0002] Release paper is a kind of paper with special coating, which mainly plays the role of isolating objects with adhesion. It is usually manufactured by coating a layer of film layer on the base paper and then coating a layer of release agent. The traditional release paper has a large thickness and low softness, which affects the user experience of consumers. With the emphasis on environmental protection, the use of thinner paper to manufacture low-grammage release paper has gradually been valued, as paper is the main component of release paper. The use of less raw material for manufacturing paper to some extent makes low-grammage release paper more environmentally friendly. At present, most low-grammage release papers use paper with a grammage of about 60gsm as base paper. Although some low-grammage release papers use thin paper with a grammage as low as 16gsm or ultra-thin paper with a grammage below 10gsm as base paper, the mechanical strength of thin paper and ultra-thin paper is low and the manufacturing difficulty is high. The low mechanical strength of paper also increases the manufacturing difficulty of release paper and the mechanical strength of the manufactured release paper is generally low, which leads to the fact that release paper using thin paper or ultra-thin paper has not been widely used.

[0003] Patent document: Preparation method of high-clean release paper (publication number: CN114808540A, publication date: 2022-07-29), discloses a preparation method of high-clean release paper, including the following steps: selecting a thin paper material made by mixing nanofiber material and short fiber in a mass ratio of 3:4, then putting it into a drying chamber for moisture drying operation, hot-pressing the dried paper, and finally obtaining the original paper. The original paper obtained by using a film coating machine is coated with a layer of isolation film, and the film-coated original paper is put into a drying chamber for drying operation. The paper material forming a glue layer is transferred to a silicone oil application equipment for silicone oil application operation. The silicone oil application equipment coats a layer of silicone oil on the glue layer. The original paper coated with silicone oil film is dried and edge sealed, and then a high-clean release paper body is prepared. The moisture-proof release paper body that passes quality inspection is stored in the warehouse.

[0004] In the preparation method of the above-mentioned high-cleanliness release paper, thin paper material is used as the base paper for manufacturing release paper, which can reduce the thickness of the release paper. Since the thin paper is thin and has a smooth surface, a polypropylene and polyethylene mixture is used as the coating layer and PVA glue needs to be added to increase the adhesion. Although the polypropylene and polyethylene mixture can improve the toughness of the release paper after film formation, the thickness of the coating layer accounts for a small proportion in the release paper and cannot significantly improve the toughness of the release paper. In addition, both polypropylene and polyethylene are difficult to degrade naturally, resulting in low environmental protection of the release paper. In addition, although increasing the thickness of the coating layer can significantly improve the toughness of the release paper, it violates the original intention of low-weight release paper and increases the manufacturing cost. Therefore, there is still room for improvement. Summary of the Invention

[0005] In view of the technical defects existing in the background technology, the present invention proposes a method for manufacturing low-weight solvent-free silicone oil release paper, which solves the above technical problems and meets practical needs. The specific technical solution is as follows:

[0006] A method for manufacturing low-weight solvent-free silicone oil release paper comprises the following steps:

[0007] S1. Papermaking, wherein a plant material is beaten with a pulper to obtain plant pulp, the plant pulp is then mixed with dispersed thermoplastic fiber filaments in water and stirred to obtain a mixed slurry, the mixed slurry is then passed through a papermaking device to make paper, the water in the mixed slurry is then squeezed out to obtain primary paper, the primary paper is then conveyed through an assembly line to a stretching device, the primary paper is preheated by spraying hot water in the stretching device, heated, and then stretched by a conveying speed difference, the stretched primary paper is conveyed to a first drying device for drying, and calendered by a calender to obtain a base paper;

[0008] S2 primer, the base paper is transported to the primer device for primer operation, the primer device evenly coats a layer of primer on the surface of the base paper;

[0009] S3 drying primer, the base paper coated with primer after leaving the primer equipment immediately after transporting 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;

[0010] S4. Coating the release agent. After the intermediate paper leaves the adhesive drying device, it is transported to the release agent coating device. The release agent coating device coats a layer of release agent on the surface of the bottom glue of the intermediate paper.

[0011] S5 drying release agent, the intermediate paper surface is coated with a layer of release agent and then transported to the second drying device for drying operation, after drying the release agent solidifies to form a release layer to obtain release paper, the release paper weight is 15-30gsm;

[0012] S6. Rehydration and rewetting: the cured release paper is rehydrated and rewetted in a non-contact manner during transportation;

[0013] S7. Rewind the release paper. After replenishing water and rewetting, the release paper is rewound by a rewinding device.

[0014] As a further technical solution of the present invention, the stretching equipment is sequentially provided with a spraying mechanism, a heating mechanism, a differential roller, and at least one pressing roller, the spraying mechanism is composed of a plurality of spray heads with ports facing downward, a guide roller is provided at the bottom of the differential roller close to the heating mechanism, the differential roller and the bottom of the pressing roller are jointly abutted against a conveying mechanism, the conveying direction of the conveying mechanism is opposite to the direction of rotation of the differential roller along the axis, the pressing roller and the differential roller rotate in the same direction along their respective axes, the linear speed of the pressing roller along the axis is the same as the conveying speed of the conveying mechanism, the guide roller and the differential roller rotate in opposite directions along their respective axes and have the same linear speed, and the ratio of the linear speed of the differential roller to the pressing roller along their respective axes is 1:1.2-1:2.

[0015] As a further technical solution of the present invention, the conveying speed of the assembly line equipment is 0.5-1m / s, the linear speeds of the differential roller and the guide roller rotating along their respective axes are both 0.5-2.5m / s, and the linear speed of the roller rotating along the axis and the conveying speed of the conveying mechanism are both 1-3m / s.

[0016] As a further technical solution of the present invention, the temperature of the hot water sprayed by the spraying mechanism is 80-100°C, and the operating temperature of the heating mechanism is 110-150°C.

[0017] As a further technical solution of the present invention, the plant pulp is selected from at least one of broadleaf pulp and coniferous pulp, the thermoplastic fiber yarn is selected from at least one of phenolic resin fiber and polybutylene succinate fiber, and the dry weight ratio of the plant pulp to the thermoplastic fiber yarn is 1:0.5-1:2.

[0018] As a further technical solution of the present invention, the operating temperature of the first drying equipment is 80-120°C.

[0019] As a further technical solution of the present invention, the base glue includes PVA glue and latex, and the dry coating weight of the base glue is 0.8-1.3gsm.

[0020] As a further technical solution of the present invention, the working temperature of the glue drying equipment is 70-120°C.

[0021] As a further technical solution of the present invention, the release agent is solvent-free silicone oil, and the dry coating weight of the release agent is 0.6-1 gsm.

[0022] As a further technical scheme of the present application, the working temperature of the second drying device is 80-140 DEG C.

[0023] The present application has the beneficial effects in that:

[0024] The present application adopts plant pulp and thermoplastic fiber to mix and make paper, based on the characteristics that the thermoplastic fiber can be repeatedly reshaped and shaped after being heated to a certain temperature, the base paper with low grammage is obtained by stretching the paper before forming through the speed difference in the process of papermaking, then the base paper is coated with a primer and a release agent to obtain a low-grammage release paper, and the release paper of the present application has better mechanical strength than the release paper with the same or even higher grammage due to the higher strength and toughness of the thermoplastic fiber after solidification, the present application can reduce the amount of pulp added in the papermaking process, and achieve higher environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a process flow chart of a manufacturing method of a low-grammage solvent-free silicone oil release paper.

[0026] Figure 2 It is a structure schematic diagram of a stretching mechanism of a manufacturing method of a low-grammage solvent-free silicone oil release paper.

[0027] Among them: stretching device 1, spraying mechanism 2, spraying head 21, heating mechanism 3, differential roller 4, roller 5, guide roller 6, conveying mechanism 7. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described below in conjunction with the drawings and related examples, and the embodiments of the present application are not limited to the following examples, and the present application relates to the necessary components in the related technical field, which should be regarded as the known technology in the technical field, and can be known and mastered by the person skilled in the art.

[0029] As Figure 1 shown, a manufacturing method of a low-grammage solvent-free silicone oil release paper, comprising the following steps:

[0030] S1. Papermaking, the plant raw material is beaten by a beater to obtain plant pulp, then the plant pulp and dispersed thermoplastic fiber are mixed and stirred uniformly in water to obtain mixed pulp, then the mixed pulp is papered by a papermaking device, then the water in the mixed pulp is squeezed out by extrusion to obtain a primary paper, then the primary paper is conveyed to the stretching device 1 by a flow line device, the primary paper is preheated by spraying hot water, heated, and then stretched by the speed difference, the stretched primary paper is conveyed to the first drying device for drying and calendering by a calender to obtain a base paper;

[0031] S2 primer, the base paper is transported to the primer device for primer operation, the primer device evenly coats a layer of primer on the surface of the base paper;

[0032] S3 drying primer, the base paper coated with primer after leaving the primer equipment immediately after transporting 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;

[0033] S4. Coating the release agent. After the intermediate paper leaves the adhesive drying device, it is transported to the release agent coating device. The release agent coating device coats a layer of release agent on the surface of the bottom glue of the intermediate paper.

[0034] S5 drying release agent, the intermediate paper surface is coated with a layer of release agent and then transported to the second drying device for drying operation, after drying the release agent solidifies to form a release layer to obtain release paper, the release paper weight is 15-30gsm;

[0035] S6. Rehydration and rewetting: the cured release paper is rehydrated and rewetted in a non-contact manner during transportation;

[0036] S7. Rewind the release paper. After replenishing water and rewetting, the release paper is rewound by a rewinding device.

[0037] It should be noted that after completing steps S1-S5, the release paper obtained can repeat the relevant operations of steps S2-S5 on the side not coated with the release agent, and then perform steps S6 and S7 to form double-sided release paper, which can meet more usage and processing requirements.

[0038] In order to cooperate with the implementation of the release paper manufacturing method of the present invention, it is necessary to adopt several release paper manufacturing equipment compatible with the manufacturing method, including the following equipment arranged in sequence according to each step of the release paper manufacturing method: a pulping machine for grinding plant raw materials into plant pulp, a papermaking equipment for making primary paper, an assembly line equipment connected to the papermaking equipment and conveying the primary paper, a stretching equipment 1 for stretching the primary paper conveyed by the assembly line equipment, a first drying equipment for drying the stretched primary paper, a calender for calendering the dried primary paper, a first winding equipment for winding the base paper, an unwinding equipment for unwinding the base paper, a primer coating equipment for primer coating the surface of the base paper, a glue drying equipment for heating and drying the intermediate paper after primer coating, a release agent coating equipment for coating a release agent on the primer side of the intermediate paper, a second drying equipment for drying the release agent, a steam humidification equipment or a centrifugal humidification equipment for replenishing water and rehumidifying the release paper, and a winding equipment for winding the release paper after replenishing water and rehumidifying.

[0039] like Figure 2As shown, as one of the preferred embodiments of the present application, the stretching device 1 is sequentially provided with a spraying mechanism 2, a heating mechanism 3, a differential roller 4, and at least one rolling roller 5. The spraying mechanism 2 is composed of a plurality of downward spraying heads 21. The differential roller 4 is provided with a guide roller 6 at the top near the side of the heating mechanism 3. The differential roller 4 and the bottom of the rolling roller 5 are jointly abutted by a conveying mechanism 7. The conveying direction of the conveying mechanism 7 is opposite to the direction of the differential roller 4 rotating along the axis. The rolling roller 5 and the differential roller 4 rotate along the respective axes in the same direction. The linear speed of the rolling roller 5 rotating along the axis is the same as the conveying speed of the conveying mechanism 7. The guide roller 6 and the differential roller 4 rotate along the respective axes in opposite directions with the same linear speed. The ratio of the linear speed of the differential roller 4 rotating along the axis to the linear speed of the rolling roller 5 rotating along the axis is 1:1.2-1:2.

[0040] The heating mechanism 3 of the present application preferably adopts an infrared radiator. The differential roller 4, the rolling roller 5, and the guide roller 6 all preferably adopt rubber rollers. The conveying mechanism 7 preferably adopts a rubber conveying belt. The spraying head 21 preferably adopts an atomizing spraying head. A plurality of spraying heads 21 are jointly connected to an external heating water boiler through a water pipe. The primary paper enters the stretching device 1 from the side near the spraying mechanism 2, and then sequentially passes through the lower part of the spraying mechanism 2 and the heating mechanism 3, the top of the guide roller 6, the bottom of the differential roller 4, and the top of the conveying mechanism 7, and then passes through the bottom of the rolling roller 5 and the conveying mechanism 7, and then leaves the stretching device 1. The top of the guide roller 6 is located above the horizontal plane of the bottom of the differential roller 4, so that the primary paper can be inclined downward to enter the space between the bottom of the differential roller 4 and the top of the conveying mechanism 7. The primary paper contacts the differential roller 4 before entering the space between the bottom of the differential roller 4 and the top of the conveying mechanism 7, thereby avoiding the primary paper being stretched between the guide roller 6 and the differential roller 4. Since the surface of the conveying mechanism 7 is elastic, the primary paper can enter the space between the bottom of the differential roller 4 and the top of the conveying mechanism 7, and the space between the bottom of the rolling roller 5 and the conveying mechanism 7, thereby being conveyed by the conveying mechanism 7.

[0041] In step S1, according to the papermaking method and using common papermaking equipment, a primary paper is obtained after papermaking and extrusion. Then, the primary paper is preheated by the hot water sprayed by the spraying mechanism 2 in the stretching device 1, so that the primary paper is kept moist while the thermoplastic fiber filaments inside are preliminarily softened. Then, the thermoplastic fiber filaments are further heated to a state close to or molten by the heating mechanism 3. Then, the primary paper is guided by the guide roller 6 into the space between the differential roller 4 and the conveying mechanism 7. Due to the speed difference between the differential roller 4 and the conveying mechanism 7 and the fact that the conveying mechanism The speed of 7 is higher, and the primary paper will be stretched due to the speed difference. Since the thermoplastic fiber filaments are thermoplastic and the primary paper is still in a wet state, the thermoplastic fiber filaments will be stretched and the plant fibers will be displaced under the lubrication of water, so that the primary paper is stretched without being broken. Then, the primary paper is rolled by the rolling roller 5 to restore the loose structure of the primary paper after stretching to a tight structure. In this process, some thermoplastic fiber filaments fill the loose position, so that the stretched primary paper is restored to a flat state, and the thickness of the stretched primary paper will become thinner.

[0042] It should be noted that adjusting the speed difference between the differential roller 4 and the conveying mechanism 7 can control the stretching ratio of the primary paper. For example, when the speed ratio of the differential roller 4 to the conveying mechanism 7 is 1:1.2, the length of the primary paper will be stretched to 1.2 times the original length, thereby reducing the thickness by 10%. In order to avoid the primary paper being broken due to excessive speed difference between the differential roller 4 and the conveying mechanism 7, the speed ratio of the differential roller 4 to the conveying mechanism 7 is up to 1:2. A stretching device 1 can stretch the primary paper to twice its original length and reduce the thickness by 50%.

[0043] The primary paper manufactured by the papermaking equipment in the present invention has a minimum grammage of 60gsm after being shaped by a roller shaping device and dried by a first drying device without being stretched by the stretching device 1. Then, the base paper obtained by stretching, shaping and drying by a stretching device 1 and a first drying device has a minimum grammage of 30gsm. The current common thin paper has a grammage of 16-20gsm, and the grammage of this base paper is still quite different from that of thin paper. The applicant then connects two stretching devices 1 in series, allowing the primary paper that has undergone one stretching and shaping to enter the second stretching device 1 for secondary stretching. Since the thickness of the primary paper becomes thinner after the first stretching and it is difficult to withstand a larger ratio of stretching, the speed ratio of the differential roller 4 and the conveying mechanism 7 in the second stretching device 1 is set to 1:1.5, so that the primary paper can be stretched for the second time smoothly. After the primary paper is stretched twice, its length is 3 times the original length and its thickness is reduced by 66.67%. The secondary stretched base paper obtained after drying by the first drying device has a minimum grammage of 20gsm.

[0044] The applicant then continued to connect multiple stretching devices 1 in series to achieve five stretching devices 1 connected in series to stretch the primary paper five times. The speed ratios of the differential roller 4 and the conveying mechanism 7 in the five stretching devices 1 were set to 1:2, 1:1.5, 1:1.33, 1:1.25, and 1:1.2 respectively. After five stretchings, the length of the primary paper was 6 times the original length and the thickness was reduced by 83.33%. The five-times stretched base paper obtained after drying in the first drying device had a minimum grammage of 10 gsm. After five stretchings, the thickness of the primary paper was very thin. Although it can still be stretched, it can only withstand extremely low stretching ratios, and each stretching will increase the manufacturing cost of the base paper. Based on cost considerations, the present invention uses a maximum of five stretching devices 1 connected in series to stretch the primary paper five times, and preferably uses two stretching devices 1 connected in series to stretch the primary paper twice.

[0045] As a further preferred embodiment of the present invention, the conveying speed of the assembly line equipment is 0.5-1m / s, the linear speeds of the differential roller 4 and the guide roller 6 rotating along their respective axes are both 0.5-2.5m / s, and the linear speed of the roller 5 rotating along its axis and the conveying speed of the conveying mechanism 7 are both 1-3m / s.

[0046] The running speed of each device and component in the present application needs to be adjusted according to the stretching times of the primary paper, so that the primary paper keeps a speed of 2-3 m / s when entering the first drying device for drying. When stretching once, the conveying speed of the assembly line device is preferably set to 1 m / s, the linear speed of the differential roller 4 and the guide roller 6 rotating along their respective axes is set to 1 m / s, and the linear speed of the roller pressing roller 5 rotating along the axis and the conveying speed of the conveying mechanism 7 are both set to 2 m / s, and the speed of the primary paper when entering the first drying device is 2 m / s. When stretching twice, the conveying speed of the assembly line device is preferably set to 0.8 m / s, in the first stretching device 1, the linear speed of the differential roller 4 and the guide roller 6 rotating along their respective axes is set to 0.8 m / s, and the linear speed of the roller pressing roller 5 rotating along the axis and the conveying speed of the conveying mechanism 7 are both set to 1.6 m / s, in the second stretching device 1, the linear speed of the differential roller 4 and the guide roller 6 rotating along their respective axes is set to 1.6 m / s, and the linear speed of the roller pressing roller 5 rotating along the axis and the conveying speed of the conveying mechanism 7 are both set to 2.4 m / s, and the speed of the primary paper when entering the first drying device is 2.4 m / s. Since the conveying speed of the primary paper is improved after each stretching through the stretching device 1, the conveying speed of the primary paper during the first stretching needs to be adjusted appropriately according to the stretching times, so as to avoid the conveying speed of the primary paper after completing the stretching being too fast, which makes it difficult for the first drying device to dry the primary paper. At the same time, since the more the stretching times of the primary paper, the thinner the primary paper and the shorter the drying time required, the increase of the conveying speed of the primary paper with the increase of the stretching times can reduce the drying time, so that the first drying device can be suitable for primary papers with different stretching times. When stretching five times, the conveying speed of the assembly line device is preferably set to 0.5 m / s, and the speed of the final primary paper when entering the first drying device is 3 m / s.

[0047] As one of the preferred embodiments of the present application, the temperature of the hot water sprayed by the spraying mechanism 2 is 80-100℃, and the working temperature of the heating mechanism 3 is 110-150℃.

[0048] The temperature of the hot water sprayed by the spraying mechanism 2 of the present invention needs to be adjusted according to the number of stretching processes of the stretching equipment 1 in which it is located. Since the primary paper is mainly heated by the heating mechanism 3, the temperature of the hot water sprayed by the spraying mechanism 2 in the first stretching process is preferably 90°C, which ensures that the primary paper is moistened and quickly preheated while reducing unnecessary energy consumption. The temperature of the hot water sprayed by the spraying mechanism 2 in each subsequent stretching process is preferably 100°C. Since the primary paper has been heated to a higher temperature after the first stretching, spraying 100°C hot water can keep the primary paper moist while maintaining a high temperature, which can reduce the working temperature of the heating mechanism 3; the working temperature of the heating mechanism 3 It needs to be adjusted according to the number of stretching processes the stretching equipment 1 is in. The working temperature of the heating mechanism 3 in the first stretching process is preferably 150°C. The primary paper before the first stretching is at room temperature. Even if it is preheated with hot water, its temperature can only reach about 60°C at most. Therefore, during the first stretching, the heating mechanism 3 needs to use a higher working temperature to quickly heat up the thermoplastic fiber filaments in the primary paper to avoid being unable to stretch. As the number of stretching times increases and the stretching ratio decreases, the primary paper has been heated to a higher temperature after one stretching. In each subsequent stretching process, the working temperature of the heating mechanism 3 needs to be gradually reduced to reduce unnecessary energy consumption.

[0049] Furthermore, after the base paper is dried, it needs to be calendered immediately by a calender. Calendering can improve the surface flatness of the base paper and reduce the amount of primer in the process of manufacturing release paper. Calendering can shape the thermoplastic fiber filaments inside the base paper and increase the tightness inside the base paper.

[0050] As one of the preferred embodiments of the present invention, the plant pulp is selected from at least one of broadleaf pulp and coniferous pulp, the thermoplastic fiber yarn is selected from at least one of phenolic resin fiber and polybutylene succinate fiber, the dry weight ratio of the plant pulp to the thermoplastic fiber yarn is 1:0.5-1:2, and the operating temperature of the first drying equipment is 80-120°C.

[0051] The broadleaf wood pulp and coniferous wood pulp selected from the plant pulp of the present invention are both lightweight wood pulps and are preferred raw materials for making lightweight paper. The thermoplastic fiber filaments are preferably polybutylene succinate fibers. Polybutylene succinate has good biocompatibility and biodegradability in the soil and can be completely degraded by microorganisms in nature. It is a green and environmentally friendly material. The melting temperature of polybutylene succinate is 114°C. When the hot water sprayed by the spraying mechanism 2 penetrates into the interior of the primary paper, the thermoplastic fiber filaments will produce heat exchange with the hot water and soften, and then the heating mechanism 3 is used to heat the thermoplastic fiber filaments. The thermoplastic fiber filaments are further heated to a state close to or in a molten state, so that the thermoplastic fiber filaments can be stretched, thereby increasing the length of the primary paper while reducing the thickness; the ratio of the dry weight of the plant pulp to the thermoplastic fiber filaments needs to be determined according to the number of stretching times. When two stretching times are used, the ratio of the dry weight of the plant pulp to the thermoplastic fiber filaments is preferably 1:1. As the number of stretching times increases, the proportion of thermoplastic fiber filaments added needs to be appropriately increased. The operating temperature of the first drying equipment is preferably 105°C to ensure drying efficiency while preventing the thermoplastic fiber filaments from being heated to a molten state.

[0052] Furthermore, since the melting temperature of phenolic resin is lower and it can be heated to a molten state faster, when the thermoplastic fiber filaments are a mixture of phenolic resin and polybutylene succinate or phenolic resin, the proportion of thermoplastic fiber filaments added can be appropriately reduced, and the operating temperature of the first drying equipment also needs to be appropriately reduced.

[0053] As one of the preferred embodiments of the present invention, the base glue includes PVA glue and latex, and the dry coating weight of the base glue is 0.8-1.3 gsm.

[0054] In step S2, PVA glue has high strength and high adhesion, while latex has good flexibility and weather resistance. The mixture of PVA glue and latex can obtain higher strength and weather resistance while maintaining good flexibility and adhesion. At the same time, due to the better adhesion between thermoplastic fiber filaments and primer, the coating dry weight of primer can be reduced. When the content of thermoplastic fiber filaments in the base paper is high, the coating dry weight of primer can be as low as 0.8gsm. The primer equipment includes a traction mechanism, which allows the base paper to be coated with primer through a glue-coating anilox roller and a glue-coating silicon pressure roller. The primer equipment is suitable for white latex and PVA. After the primer is applied, the base paper is immediately transferred to the glue drying equipment for drying. An online glue quantity detection device is provided between the primer coating equipment and the glue drying equipment to monitor the primer coating quantity 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 primer coating quality of the release paper is improved. During the transmission of the base paper, the tension roller can make real-time compensation according to the fluctuation situation during the transmission process, thereby ensuring the stability of the tension during the primer coating and avoiding the fluctuation of the primer coating quantity caused by the tension fluctuation.

[0055] As one of the preferred embodiments of the present application, the working temperature of the glue drying device is 70-120 DEG C.

[0056] In step S3, the glue drying device comprises four relatively independent and serial glue drying box assemblies arranged in sequence, i.e., a first glue drying box, a second glue drying box, a third glue drying box and a fourth glue drying box.

[0057] In the present application, the working temperature of the first glue drying box is 70-95 DEG C, the working temperature of the second glue drying box is 90-110 DEG C, the working temperature of the third glue drying box is 100-120 DEG C, and the working temperature of the fourth glue drying box is 80-105 DEG C.

[0058] The working temperature of the four glue drying boxes gradually increases and then decreases in sequence, which can make the base paper gradually absorb heat and stably increase in temperature during the transmission process, so that the water, solvent and volatile substances in the base paper gradually evaporate.

[0059] After drying, the intermediate paper can be optionally roller-shaped using a structure similar to that of the roller 5 and the conveying mechanism 7. Since the thermoplastic fiber filaments soften again during the drying process and the thermoplastic fiber filaments account for a relatively high proportion in the base paper, the softening of the thermoplastic fiber filaments may cause the base paper structure to become loose. Although this does not affect the grammage of the release paper product, it may reduce the mechanical strength of the release paper product. Rolling the intermediate paper can reshape the thermoplastic fiber filaments inside the base paper, keeping the base paper tight to improve the mechanical strength of the release paper product. In addition, although the uniformity of the primer coating is improved by adjusting the spraying speed and nozzle distance of the primer coating equipment, the PVA glue and white latex cannot be reshaped after curing, resulting in uneven defects in the coating layer. During the roller-shaped reshaping process of the base paper, the coating layer has a certain tensile elasticity and can deform as the base paper is reshaped. The uneven areas on the surface of the coating layer can be formed into a flatter surface after the roller deformation, thereby improving the flatness of the release paper product.

[0060] As one of the preferred embodiments of the present invention, the release agent is solvent-free silicone oil, and the dry coating weight of the release agent is 0.6-1 gsm, preferably 0.8 gsm.

[0061] In step S4, compared with solvent-based silicone oil, solvent-free silicone oil has the advantages of being more environmentally friendly, more stable, more lubricated, more resistant to high temperatures, and lower cost. It can improve the performance of release paper while reducing the production cost of release paper. The release agent coating equipment preferably adopts a device for coating the release agent based on the film transfer method. A correction mechanism, a tension isolation mechanism, and a cooling mechanism are provided between the glue baking equipment and the release agent coating equipment. The intermediate paper passes through the above-mentioned mechanisms in sequence and enters the release agent coating equipment for coating the release agent. The release agent coating equipment includes a glue roller, a metering roller, a first transfer roller, a second transfer roller, a coating roller, and a silicon pressure roller that are arranged in sequence in the order of material advancement. The paper passes through the pressure zone between the coating roller and the silicon pressure roller to achieve release agent coating. The present invention uses a lower dry amount of release agent coating, which can avoid the release layer from being too thick after the release agent is cured, thereby affecting the softness of the release paper.

[0062] As one of the preferred embodiments of the present invention, the operating temperature of the second drying equipment is 80-140°C.

[0063] In step S5, the second 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 suspended silicon oven assemblies; wherein the operating temperature of the first silicon oven is 85-100°C, the operating temperature of the second silicon oven is 95-120°C, the operating temperature of the third silicon oven is 110-130°C, the operating temperature of the fourth silicon oven is 120-140°C, the operating temperature of the fifth silicon oven is 110-125°C, the operating temperature of the sixth silicon oven is 100-115°C, the operating temperature of the seventh silicon oven is 90-105°C, and the operating temperature of the eighth silicon oven is 80-95°C.

[0064] The working temperatures of the eight suspended silicon ovens are gradually increased and then decreased in sequence. The eight suspended silicon ovens can also allow the intermediate paper coated with the release agent to be transported at a uniform speed while extending the drying time. In addition, the temperature is increased in a step-by-step manner so that the release agent gradually absorbs heat during the transmission of the intermediate paper and the temperature is increased steadily, causing the surfactant in the release agent to gradually evaporate. This can also avoid the problem of unevenness or even cracking of the release layer 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 a release paper.

[0065] The dried release paper needs to be rolled and shaped using a structure similar to that of a rolling roller 5 and a conveying mechanism 7. Since the thermoplastic fiber filaments soften again during the drying process and the thermoplastic fiber filaments account for a high proportion in the base paper, the softening of the thermoplastic fiber filaments may cause the base paper structure to become loose. Although it will not affect the grammage of the release paper, it may reduce the mechanical strength of the release paper. Rolling the middle paper can allow the thermoplastic fiber filaments inside the base paper to reshape, keeping the inside of the base paper tight to improve the mechanical strength of the release paper.

[0066] The dried release paper needs to be rolled and shaped using a structure similar to that of the rolling roller 5 and the conveying mechanism 7 to prevent the thermoplastic fiber filaments in the base paper from softening during the drying process and causing the base paper structure to become loose. Although this will not affect the thickness of the release paper, it will reduce the mechanical strength of the finished release paper.

[0067] In step S6, after the release paper is dried by the second 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, which makes it easy to wrinkle, turn over, and break during transportation. Therefore, after cooling, the release paper needs to be rehumidified by a non-contact steam rehumidification box or a centrifugal humidification device 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 S7. The release paper cannot be completely soaked by replenishing water once, and 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 water replenishment and rehumidification process, and the non-contact water replenishment and rehumidification can improve the uniformity of rewetting.

[0068] The present invention preferably adopts the method of manufacturing a base paper with a grammage of 13-28 gsm based on step S1, and finally manufacturing a release paper with a grammage of 15-30 gsm.

[0069] The present invention is further described below by way of examples and comparative examples.

[0070] Example

[0071] The hardwood pulp and the dispersed polybutylene succinate fiber are mixed in water in a dry weight ratio of 1:1 and stirred evenly to obtain a mixed pulp, and then the mixed pulp is papermade and extruded through a papermaking equipment to obtain primary paper, and then the primary paper is transported to the first stretching equipment 1 through an assembly line equipment for the first stretching, and then the primary paper that has completed the first stretching is stretched for the second time through a second stretching equipment 1, and the primary paper after the two stretchings is transported to the first drying equipment for drying and calendered by a calender to obtain a base paper with a grammage of 20gsm, and then the base paper is evenly coated with a layer of primer on its surface through a primer coating equipment, and after the base paper is coated with the primer, it is dried through a glue baking equipment to obtain an intermediate paper, and then a layer of release agent is coated on the primer surface of the intermediate paper through a release agent coating equipment, and after the intermediate paper is coated with the release agent, it is dried through a second drying equipment to obtain a first release paper.

[0072] Comparative Example 1

[0073] The difference from the embodiment is that the base paper adopts a thin paper with a grammage of 20 gsm commonly available on the market, and the second release paper is finally prepared.

[0074] Comparative Example 2

[0075] The difference from the embodiment is that the base paper adopts the common full-wood pulp paper with a grammage of 60gsm on the market, and the third release paper is finally prepared.

[0076] Comparative Example 3

[0077] The difference from the embodiment is that the base paper adopts the common full-wood pulp paper with a grammage of 100 gsm on the market, and the fourth release paper is finally produced.

[0078] The mechanical strength of the release paper is now tested. According to the standard for release paper for sanitary products (GB / T27731-2011), the first release paper, the second release paper, the third release paper, and the fourth release paper are tested for tensile strength and tear index. The results are shown in Table 1:

[0079]

[0080] Table 1

[0081] Analysis of the data in Table 1 shows that although the first release paper and the second release paper 1 both use a base paper with a gram weight of 20 gsm, the base paper in the first release paper is added with polybutylene succinate fiber, and the mechanical strength of the final release paper is significantly higher. The mechanical strength of the first release paper and the fourth release paper is similar. It can be seen that the mechanical strength of the base paper with a gram weight of 20 gsm manufactured by the present invention is comparable to that of all-wood pulp paper with a gram weight of 100 gsm.

[0082] The present invention uses a mixture of thermoplastic fiber filaments and plant pulp to make paper. Based on the characteristic that the thermoplastic fiber filaments can be repeatedly reshaped and shaped after being heated to a certain temperature, the paper is stretched before being formed by the speed difference of the conveying during the papermaking process, thereby reducing the thickness of the formed paper and obtaining a low-weight base paper. At the same time, since the thermoplastic fiber filaments have higher strength and toughness than plant fibers after curing, the base paper has better mechanical strength than all-wood pulp paper of the same or even higher weight. The release paper manufactured by the present invention can reduce the amount of pulp added in the papermaking process, achieve higher environmental protection, and the gram weight and thickness of the release paper are both lower, which can reduce the cost of transporting the release paper.

[0083] 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 method for producing low-weight solvent-free silicone oil release paper, characterized in that: The following steps are included: S1. Papermaking, wherein a plant material is beaten with a pulper to obtain plant pulp, the plant pulp is then mixed with dispersed thermoplastic fiber filaments in water and stirred to obtain a mixed slurry, the mixed slurry is then passed through a papermaking device to make paper, the water in the mixed slurry is then squeezed out to obtain primary paper, the primary paper is then conveyed through an assembly line to a stretching device, the primary paper is preheated by spraying hot water in the stretching device, heated, and then stretched by a conveying speed difference, the stretched primary paper is conveyed to a first drying device for drying, and calendered by a calender to obtain a base paper; The stretching equipment is sequentially provided with a spraying mechanism, a heating mechanism, a differential roller, and at least one pressing roller, wherein the spraying mechanism is composed of a plurality of spray heads with ports facing downwards, a guide roller is provided on the top of the differential roller near the heating mechanism, the differential roller and the pressing roller are abutted against a conveying mechanism at the bottom, the conveying direction of the conveying mechanism is opposite to the direction of rotation of the differential roller along the axis, the pressing roller and the differential roller rotate in the same direction along their respective axes, the linear speed of the pressing roller along the axis is the same as the conveying speed of the conveying mechanism, the guide roller and the differential roller rotate in opposite directions along their respective axes and at the same linear speed, and the ratio of the linear speeds of the differential roller and the pressing roller along their respective axes is 1:1.2-1:2; The temperature of the hot water sprayed by the spraying mechanism is 80-100°C, and the operating temperature of the heating mechanism is 110-150°C; The plant pulp is selected from at least one of hardwood pulp and softwood pulp, the thermoplastic fiber is selected from polybutylene succinate fiber, and the dry weight ratio of the plant pulp to the thermoplastic fiber is 1:0.5-1:2; S2 primer, the base paper is transported to the primer device for primer operation, the primer device evenly coats a layer of primer on the surface of the base paper; S3 drying primer, the base paper coated with primer after leaving the primer equipment immediately after transporting 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. Coating the release agent. After the intermediate paper leaves the adhesive drying device, it is transported to the release agent coating device. The release agent coating device coats a layer of release agent on the surface of the bottom glue of the intermediate paper. S5 drying release agent, the intermediate paper surface is coated with a layer of release agent and then transported to the second drying device for drying operation, after drying the release agent solidifies to form a release layer to obtain release paper, the release paper weight is 15-30gsm; S6. Rehydration and rewetting: the cured release paper is rehydrated and rewetted in a non-contact manner during transportation; S7. Rewind the release paper. After replenishing water and rewetting, the release paper is rewound by a rewinding device.

2. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The conveying speed of the assembly line equipment is 0.5-1m / s, the linear speeds of the differential roller and the guide roller rotating along their respective axes are both 0.5-2.5m / s, and the linear speed of the pressing roller rotating along its axis and the conveying speed of the conveying mechanism are both 1-3m / s.

3. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The operating temperature of the first drying equipment is 80-120°C.

4. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The dry coating weight of the primer is 0.8-1.3 gsm.

5. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The working temperature of the glue drying equipment is 70-120°C.

6. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The release agent is solvent-free silicone oil, and the coating dry weight of the release agent is 0.6-1gsm.

7. The method for producing solvent-free silicone oil release paper according to claim 1, wherein: The operating temperature of the second drying equipment is 80-140°C.

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