A method for preparing a waterproof and oil-proof coated paper

Abstract

The application discloses a preparation method of waterproof and oil-proof coated card paper and belongs to the technical field of coated paper. The preparation method comprises the following steps: a beating step, a wire dewatering step, a compounding step, a pressing step, a pre-drying step, a surface sizing step, a post-drying step, a hard calendering step, a coating step, a soft calendering step and a winding step. The waterproof and oil-proof coated card paper prepared by the method has the advantages of high waterproofness and oil-proofness, low preparation cost, recyclability, reduced waste paper loss, reduced coating amount and improved uniformity of coating thickness.

Description

Technical Field

[0001] This invention relates to the field of coated paper technology, and more specifically, to a method for preparing waterproof and oil-resistant coated cardboard. Background Technology

[0002] Paper tableware, such as paper cups, paper bowls, and paper lunch boxes, is widely used in takeout and dine-in services and represents a promising alternative to plastic. However, to achieve barrier properties against water and oil, a plastic film (coating) needs to be deposited onto the base paper. Currently, the vast majority of these films on the market are made of polyethylene (PE). However, PE coated products have drawbacks such as being non-degradable, non-re-sizing, and difficult to recycle. While biodegradable bioplastic (PLA, Bio-PBS) coated products are biodegradable, they face challenges due to insufficient domestic production capacity and high prices. Furthermore, biodegradable plastic coated products also present recycling difficulties.

[0003] In response to the industry's demand for green and environmentally friendly products, water-based coating products for food packaging are a new type of environmentally friendly material that uses water-based biodegradable coatings to coat the base paper. Compared with traditional lamination processes, water-based coatings have the advantages of saving resources, being re-sizing, and being recyclable, while meeting the requirements for use.

[0004] However, existing methods of using water-based biodegradable coatings to produce waterproof and oil-resistant coated cardboard involve a separate post-coating process outside the paper machine, resulting in low operating efficiency and a large amount of paper waste. In addition, the off-machine coating process uses conventional doctor blade coating technology, which results in relatively uneven coating thickness. To achieve the required water and oil resistance, it is necessary to increase the coating load.

[0005] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing waterproof and oil-resistant coated cardboard, which addresses the above-mentioned shortcomings and achieves the following objectives: improving the waterproof and oil-resistant properties of the prepared waterproof and oil-resistant coated cardboard while reducing the preparation cost, achieving the recyclability of the waterproof and oil-resistant coated cardboard, reducing paper waste, reducing the coating amount, and improving the uniformity of the coating thickness.

[0007] To solve the above technical problems, the present invention adopts the following technical solution:

[0008] A method for preparing waterproof and oil-resistant coated cardboard includes the following steps: pulping, web-to-web dewatering, lamination, pressing, pre-drying, surface sizing, post-drying, hard calendering, coating, soft calendering, and winding.

[0009] The pulping process is divided into pulping of the surface layer pulp, the lining pulp, the core layer pulp, and the bottom layer pulp;

[0010] The composition of the surface layer slurry is: 0-30% bleached hardwood pulp + 70-100% bleached softwood pulp;

[0011] The composition of the lining slurry is: 15-30% bleached softwood pulp + 70-85% chemimechanical pulp;

[0012] The composition of the core pulp is: 0-30% bleached softwood pulp + 70-100% chemimechanical pulp + 0-20% waste paper;

[0013] The composition of the underlying pulp is: 0-50% bleached hardwood pulp + 50-100% bleached softwood pulp;

[0014] The bleached hardwood pulp has a tensile index ≥ 50 N·m / g and a bursting index ≥ 5.0 kPa·m. 2 / g, flexural endurance index ≥40 times, brightness ≥88%;

[0015] The bleached softwood pulp has a tensile index ≥ 80 N·m / g and a bursting index ≥ 8.0 kPa·m. 2 / g, flexural endurance index ≥700 times, brightness ≥88%;

[0016] The chemimechanical pulp has a freeness of 300, a brightness of 75%, a bulk of >2.0 cm3 / g, a tensile index ≥30 N.m / g, a fiber bundle content <0.10%, and a pH value of 6.0-8.0.

[0017] The raw materials for the chemimechanical pulp are one or more of poplar, eucalyptus, and acacia.

[0018] The waste paper is pulp after being decomposed, screened, and refined by the waste paper treatment system;

[0019] The sizing agent used in the surface layer, lining layer, core layer, and bottom layer slurry is one or more of ASA sizing agent, aluminum sulfate, and rosin sizing agent;

[0020] The oven-dry dosage of the ASA sizing agent is 1-8 kg / ton of paper;

[0021] The amount of aluminum sulfate used is 10-30 kg / ton of paper;

[0022] The oven-dry dosage of the rosin sizing agent is 10-30 kg / ton of paper;

[0023] The composite step involves combining the surface layer slurry, the lining slurry, the core layer slurry, and the bottom layer slurry.

[0024] The surface sizing agent used in the surface sizing step is a combination of enzymatically hydrolyzed starch solution and a base surface sizing agent;

[0025] The base surface sizing agent is one or more of styrene-acrylic surface sizing agents, acrylic surface sizing agents, and AKD sizing agents;

[0026] The oven-dry dosage of the enzymatically hydrolyzed starch solution is 10-50 kg / ton of paper;

[0027] When the base surface sizing agent is a styrene-acrylic surface sizing agent, the dosage of the styrene-acrylic surface sizing agent concentrate is 2-4 kg / ton of paper.

[0028] The manufacturer of the styrene-acrylic surface sizing agent is Solis Chemical Co., Ltd., and the model is imPress™ST-737.

[0029] When the base surface sizing agent is an acrylic surface sizing agent, the dosage of the acrylic surface sizing agent concentrate is 2-4 kg / ton of paper.

[0030] The acrylic surface sizing agent is manufactured by Solis Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0031] When the base surface sizing agent is AKD sizing agent, the dosage of AKD sizing agent concentrate is 2-10 kg / ton of paper.

[0032] The AKD sizing agent was provided by Weifang Tianfang Shenghong Chemical Co., Ltd., and its model is SA-301.

[0033] The preparation method of the surface sizing agent is as follows: the original starch is hydrolyzed by α-amylase, the hydrolysis temperature is controlled at 65-95℃ and the hydrolysis time is 10-30min to obtain cooked starch, which is diluted to a solid content concentration of 12%-20% and pumped to the feeding tank of the feeding station. After adding an appropriate ratio of surface sizing agent at the pump inlet of the feeding tank, the starch sizing solution is filled into the cloth chamber of the film transfer sizing machine through the pump and filter screen, and a layer of starch sizing solution is evenly coated on the surface of the sizing roller through the metering rod. Then, the starch sizing solution is evenly coated onto the paper surface through the squeezing action of the sizing roller to complete the film transfer sizing.

[0034] The linear pressure of the sizing machine is 20-40 KN / m, and the sizing amount per side of the paper is 2-8 g / m. 2 The temperature of the adhesive solution is 50-70℃;

[0035] The post-drying step involves passing the paper sheet through a single-mounted cylinder and then through a double-mounted cylinder, evaporating the bound water in the paper sheet according to the temperature curve of the drying cylinder, and drying the paper sheet to the required process value. A paper stabilizer is set in the bag area between the drying cylinders to stabilize the movement of the paper web.

[0036] The moisture content of the paper obtained after the post-drying step is 5-8%;

[0037] In the hard calendering step, the paper sheet undergoes surface calendering and cross-sectional thickness modification treatment by a hard calendering machine before coating; the hard calendering line pressure is 10-120KN / m, and the lower roll temperature is 140-200℃.

[0038] The coating process is divided into a first coating, a second coating, a third coating, and a fourth coating.

[0039] The first coating is a pre-coating applied to the front side, using a scraper coating method;

[0040] The first coating is pre-coated on the front side of the paper using a spray-type doctor blade. After the coating liquid is evenly sprayed onto the paper surface, the doctor blade scrapes a coating with uniform thickness and basis weight on the paper surface. Then, the coating is dried non-contactly by hot air drying, with the hot air drying temperature controlled at 300-420℃. Finally, it is dried in a conditioning cylinder to correct paper warping issues.

[0041] The first coating liquid is either a ready-made coating liquid or a self-made coating liquid;

[0042] When the first coating liquid is a finished coating liquid, the manufacturer of the finished coating liquid is Solis Chemical Co., Ltd., and the model is imPress™ ST-737;

[0043] When the first coating liquid is a self-made coating liquid, the composition of the self-made coating liquid, by weight, includes: 100 parts of acrylic emulsion, 0-50 parts of mineral emulsion, and 0-20 parts of wax emulsion.

[0044] Among them, the minerals are one or more of kaolin, talc powder, and mica powder;

[0045] The wax emulsion is composed of one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene wax, and polyethylene wax, with a solid content of 20-60%.

[0046] The solid content of the first coating solution is 30-70%, and the coating weight is 6-15 g / m². 2 ;

[0047] The second coating is a first functional coating applied to the front side, and the coating method is curtain coating;

[0048] The second coating involves applying the first functional coating on the front side of the paper. The functional coating is uniformly coated onto the paper surface using a curtain coating method. After coating, the coating undergoes non-contact drying with hot air at a controlled temperature of 280-400℃, followed by non-contact cooling with cold air at a controlled temperature of 25-35℃. Finally, the paper warping is calibrated using a conditioning cylinder.

[0049] The second coating liquid is a finished coating liquid, manufactured by Solis Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0050] The second coating solution has a solid content of 30-70% and a coating weight of 6-15 g / m². 2 ;

[0051] The third coating is a pre-coating on the reverse side, and the coating method is spray-type blade coating.

[0052] The third coating involves spraying the coating liquid evenly onto the paper surface, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. The coating is then dried non-contactly with hot air, with the temperature controlled at 320-360℃. After drying to the process set dryness, the paper is further dried and the warping problem is calibrated in a conditioning cylinder.

[0053] The third coating solution is either a ready-made coating solution or a homemade coating solution;

[0054] When the third coating liquid is a finished coating liquid, the manufacturer of the finished coating liquid is Solis Chemical Co., Ltd., and the model is imPress™ ST-737;

[0055] When the third coating liquid is a self-made coating liquid, the composition of the self-made coating liquid, by weight, includes: 100 parts of acrylic emulsion, 0-50 parts of mineral emulsion, and 0-20 parts of wax emulsion.

[0056] Among them, the minerals are one or more of kaolin, talc powder, and mica powder;

[0057] The wax emulsion is composed of one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene wax, and polyethylene wax, with a solid content of 20-60%.

[0058] The third coating solution has a solid content of 30-70% and a coating weight of 6-15 g / m². 2 ;

[0059] The fourth coating is the first functional coating on the reverse side, and the coating method is spray-type blade coating.

[0060] The fourth coating process involves uniformly spraying the coating liquid onto the back of the paper, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. After coating, the coating undergoes non-contact drying with hot air, controlling the temperature at 280-400℃. Once the dryness is set to the process limit, it is then cooled by non-contact cold air drying, controlling the temperature at 25-35℃. Finally, the paper warping is calibrated using a conditioning cylinder.

[0061] The fourth coating liquid is either a ready-made coating liquid or a self-made coating liquid;

[0062] When the fourth coating liquid is a finished coating liquid, the manufacturer of the finished coating liquid is Solis Chemical Co., Ltd., and the model is Basoplast™ 8903AP;

[0063] When the fourth coating liquid is a homemade coating liquid, the composition of the homemade coating liquid, by weight, includes: 100 parts acrylic emulsion, 0-50 parts mineral emulsion, and 0-20 parts wax emulsion.

[0064] Among them, the minerals are one or more of kaolin, talc powder, and mica powder;

[0065] The wax emulsion is composed of one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene wax, and polyethylene wax, with a solid content of 20-60%.

[0066] The fourth coating solution has a solid content of 30-70% and a coating weight of 6-15 g / m². 2 ;

[0067] The coating step also includes a fifth coating;

[0068] The fifth coating is a second functional coating on the front side, applied by a spray-type doctor blade coating. The functional coating material is applied a second time to the front side of the paper to give the paper special functional requirements. After the coating liquid is evenly sprayed onto the paper surface, a doctor blade is used to spread a coating of uniform thickness and basis weight on the paper surface. After coating, the coating is dried non-contactly by hot air drying, with the temperature controlled at 200-450℃. After drying to the process set dryness, it is cooled by non-contact cold air drying, with the temperature controlled at 25-35℃. Finally, the paper warping is calibrated by a conditioning cylinder.

[0069] The fifth coating liquid is manufactured by Solis Chemical Co., Ltd., and its model is Basoplast™ 8903AP.

[0070] The fifth coating has a liquid-solid content of 30-70% and a coating weight of 4-10 g / m². 2 .

[0071] In the soft calendering step, the coated base paper is fed into a soft calendering machine to perform calendering and finishing treatment on the coating; the soft calendering line pressure is 20-120KN / m, and the roller surface temperature is 120-160℃.

[0072] The winding process controls the paper temperature within the range of 30-50℃, employs constant tension winding control, and ensures constant tension and consistent tightness of the master roll.

[0073] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages:

[0074] (1) The method for preparing waterproof and oil-proof coated cardboard of the present invention adopts in-machine coating and paper forming in one step during the preparation process. Compared with the current out-of-machine coating, it can reduce paper waste and reduce production costs.

[0075] (2) The method for preparing waterproof and oil-proof coated cardboard of the present invention adopts non-contact high-efficiency hot air drying for coating and drying, which has high drying efficiency and low roughness of paper coating.

[0076] (3) In the preparation method of the waterproof and oil-proof coated cardboard of the present invention, cold air drying is used after the second and fourth hot air drying, which reduces coating problems and avoids the influence of high temperature on the performance of waterproof and oil-proof coating.

[0077] (4) The method for preparing waterproof and oil-proof coated cardboard of the present invention applies functional coating to the surface of paper during the paper machine production process, eliminating the need for subsequent PE coating or waterproof and oil-proof coating processing, greatly improving production efficiency, and producing no paper damage, reducing production waste. The coating is a water-soluble biodegradable coating, which can realize pulp recycling, reduce carbon emissions, and has no pollution to the environment.

[0078] (5) The method for preparing waterproof and oil-proof coated cardboard of the present invention improves production and operation stability and makes the coating thickness more uniform by adopting non-contact coating, and significantly reduces production costs.

[0079] (6) The method for preparing the waterproof and oil-resistant coated cardboard of the present invention can improve the waterproof and oil-resistant properties of the waterproof and oil-resistant coated cardboard, and the Cobb value (60s) of the front side of the prepared waterproof and oil-resistant coated cardboard is 0-3.8 g / m. 2 The Cobb value (60s) on the reverse side is 0.2-3.5 g / m³. 2 The kit value for the front side is 10-12, and the kit value for the back side is 10-12. Detailed Implementation

[0080] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0081] Example 1

[0082] This embodiment provides a method for preparing waterproof and oil-resistant coated cardboard, including the following steps: pulping step, wire-on dewatering step, lamination step, pressing step, pre-drying step, surface sizing step, post-drying step, hard calendering step, coating step, soft calendering step, and winding step.

[0083] The pulping process is divided into pulping of the surface layer pulp, the lining pulp, the core layer pulp, and the bottom layer pulp;

[0084] The composition of the surface layer slurry is: 10% bleached hardwood pulp + 90% bleached softwood pulp;

[0085] The composition of the lining slurry is: 15% bleached softwood pulp + 85% chemimechanical pulp;

[0086] The core layer slurry is composed of 100% chemimechanical slurry;

[0087] The composition of the underlying pulp is: 50% bleached hardwood pulp + 50% bleached softwood pulp;

[0088] The bleached hardwood pulp has a tensile index ≥ 50 N·m / g and a bursting index ≥ 5.0 kPa·m. 2 / g, flexural endurance index ≥40 times, brightness ≥88%;

[0089] The bleached softwood pulp has a tensile index ≥ 80 N·m / g and a bursting index ≥ 8.0 kPa·m. 2 / g, flexural endurance index ≥700 times, brightness ≥88%;

[0090] The chemimechanical pulp has a freeness of 300, a brightness of 75%, a bulk of >2.0 cm3 / g, a tensile index ≥30 N.m / g, a fiber bundle content <0.10%, and a pH value of 6.0-8.0.

[0091] The raw materials for the chemical pulp are a combination of poplar, eucalyptus and acacia, wherein the mass ratio of poplar, eucalyptus and acacia is 1:2:3.

[0092] The waste paper is pulp after being decomposed, screened, and refined by the waste paper treatment system;

[0093] The sizing agent used in the surface layer, liner layer, core layer and bottom layer pulp is ASA sizing agent, and the oven-dry dosage of ASA sizing agent is 2 kg / ton of paper.

[0094] The composite step involves combining the surface layer slurry, the lining slurry, the core layer slurry, and the bottom layer slurry.

[0095] The surface sizing step uses a combination of enzymatically hydrolyzed starch solution and styrene-acrylic surface sizing agent, wherein the oven-dry amount of enzymatically hydrolyzed starch solution is 10 kg / ton of paper, and the amount of styrene-acrylic surface sizing agent stock solution is 3 kg / ton of paper.

[0096] The manufacturer of the styrene-acrylic surface sizing agent is Solis (Shanghai) Chemical Co., Ltd., and the model is imPress™ ST-737.

[0097] The surface sizing step involves enzymatically hydrolyzing the original starch with α-amylase at a controlled temperature of 70°C for 15 minutes to obtain cooked starch. This starch is then diluted to a concentration of 12% solids and pumped to the feeding trough of the feeding station. After the styrene-acrylic surface sizing agent is introduced into the pump inlet of the feeding trough, the surface sizing solution is filled into the fabric chamber of the film transfer sizing machine through a pump and a filter screen. A layer of surface sizing solution is then uniformly coated onto the surface of the sizing roller using a metering rod. Finally, the surface sizing solution is uniformly coated onto the paper surface through the squeezing action of the sizing roller, thus completing the film transfer sizing.

[0098] The surface sizing machine has a linear pressure of 20 KN / m; the sizing amount per side of the paper is 2 g / m. 2 The temperature of the surface adhesive solution is 50℃;

[0099] The post-drying step involves passing the paper sheet through a single-mounted cylinder and then through a double-mounted cylinder. Following the cylinder temperature curve, the bound water in the paper sheet is evaporated, drying it to the required process values. A paper stabilizer is installed in the bag area between the cylinders to stabilize the paper web's movement. A sealed hood carries the evaporated moisture out of the hood via hot air, and the heat is recovered through a heat recovery system. After drying in the drying section, the moisture content of the pre-drying paper sheet is controlled at 6%.

[0100] Evaporating and removing the bound moisture in the paper sheet can achieve the required paper dryness and give the paper sheet suitable physical strength indicators. In the post-drying process, a paper stabilizer is used to stabilize the paper web running, improve the paper machine operating efficiency, and reduce paper breakage waste. At the same time, a closed air hood is used to reduce heat loss, recover heat energy, improve evaporation efficiency, and reduce the consumption of fresh steam.

[0101] The basis weight of the base paper obtained after the post-drying step is 170 g / m³. 2 The surface smoothness is 8s, the surface roughness is 4.45μm, and the Cobb value (60s) is 22g / m². 2 The Cobb value (60s) on the reverse side is 23 g / m³. 2 ;

[0102] In the hard calendering step, the paper sheet undergoes surface calendering and cross-width thickness modification treatment by a hard calendering machine before coating; the hard calendering line pressure is designed to be within the range of 60kN / m, and the lower roll temperature is 150℃.

[0103] After hard calendering, the paper surface smoothness is improved, which facilitates the subsequent doctor blade coating process. The paper thickness is more uniform in the transverse direction, which improves the subsequent rewinding and slitting and the performance for later customer use.

[0104] The hard calender improves the paper pressing effect by heating the lower roller; it also enables controllable zoning of the upper roller, and the local position can be adjusted according to the paper thickness detection data to achieve a base paper with uniform width thickness.

[0105] The coating process is divided into a first coating, a second coating, a third coating, and a fourth coating.

[0106] The first coating is a pre-coating on the front side, which is done by a doctor blade coating. Specifically, the coating liquid is sprayed evenly onto the paper surface, and then the doctor blade is used to scrape a coating of uniform thickness and basis weight onto the paper surface. The coating is then dried non-contactly by hot air drying, with the hot air drying temperature controlled at 380°C. Finally, the coating is dried in a conditioning cylinder to correct paper warping.

[0107] The composition of the first coating liquid, by weight, includes: 100 parts acrylic emulsion, 30 parts mineral emulsion, and 15 parts wax emulsion.

[0108] The minerals are composed of kaolin, talc powder, and mica powder in a 1:1:1 ratio; the wax emulsion is composed of polyethylene oxide wax with a solid content of 40%.

[0109] The first coating has a liquid-solid content of 50% and a coating weight of 10 g / m². 2 ;

[0110] The second coating is a first functional coating applied to the front side, and the coating method is curtain coating;

[0111] The second coating involves applying the first functional coating on the front side of the paper. The functional coating is uniformly coated onto the paper surface using a curtain coating method. After coating, the coating undergoes non-contact drying with hot air at a controlled temperature of 280°C, followed by non-contact cooling with cold air at a controlled temperature of 35°C. Finally, the paper warping is calibrated using a conditioning cylinder.

[0112] The second coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0113] The second coating solution has a solid content of 50% and a coating weight of 6 g / m². 2 ;

[0114] The third coating is a pre-coating on the reverse side, and the coating method is spray-type blade coating.

[0115] The third coating involves spraying the coating liquid evenly onto the paper surface, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. The coating is then dried non-contactly with hot air, with the temperature controlled at 320°C. After drying to the process set dryness, it is further dried in a conditioning cylinder to address paper warping issues.

[0116] The third coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is imPress™ ST-737;

[0117] The third coating solution has a solid content of 50% and a coating weight of 6 g / m². 2 ;

[0118] The fourth coating is the first functional coating on the reverse side, and the coating method is spray-type blade coating.

[0119] The fourth coating process involves uniformly spraying the coating liquid onto the back of the paper, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. After coating, the coating undergoes non-contact drying with hot air, controlling the temperature at 280°C. After drying to the process set dryness, it is then cooled by non-contact cold air drying, controlling the temperature at 35°C. Finally, the paper warping is calibrated using a conditioning cylinder.

[0120] The fourth coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0121] The fourth coating solution has a solid content of 50% and a coating weight of 4 g / m². 2 ;

[0122] In the soft calendering step, the coated base paper is fed into a soft calendering machine to perform calendering finishing treatment on the coating; the soft calendering line pressure is 40KN / m, and the roller surface temperature is 125℃.

[0123] After soft calendering, the smoothness of the paper coating and the PPS index are improved, which makes it easier to improve the subsequent printing quality for customers.

[0124] The winding process controls the paper temperature within a range of 40°C, employs constant tension winding control, and ensures constant tension and consistent tightness of the master roll.

[0125] Three paper samples were taken from the waterproof and oil-resistant coated cardboard prepared in this embodiment, namely paper sample 1, paper sample 2, and paper sample 3. The Cobb value (60s) of the front side of paper sample 1 is 3.3 g / m. 2The Cobb value (60s) on the reverse side is 3.4 g / m³. 2 The kit value on the front is 10, and the kit value on the back is 11; the Cobb value (60s) on the front of pattern 2 is 2.7 g / m². 2 The Cobb value (60s) on the reverse side is 3g / m³. 2 The kit value on the front is 11, and the kit value on the back is 10; the Cobb value (60s) on the front of pattern 1 is 3.8 g / m². 2 The Cobb value (60s) on the reverse side is 3.5 g / m³. 2 The kit value is 10 on the front and 10 on the back.

[0126] Example 2

[0127] This embodiment provides a method for preparing waterproof and oil-resistant coated cardboard, including the following steps: pulping step, wire-on dewatering step, lamination step, pressing step, pre-drying step, surface sizing step, post-drying step, hard calendering step, coating step, soft calendering step, and winding step.

[0128] The pulping process is divided into pulping of the surface layer pulp, the lining pulp, the core layer pulp, and the bottom layer pulp;

[0129] The composition of the surface layer slurry is: 15% bleached hardwood pulp + 85% bleached softwood pulp;

[0130] The composition of the lining slurry is: 20% bleached softwood pulp + 80% chemimechanical pulp;

[0131] The core pulp composition is: 10% bleached softwood pulp + 80% chemimechanical pulp + 10% waste paper;

[0132] The composition of the underlying pulp is: 40% bleached hardwood pulp + 60% bleached softwood pulp;

[0133] The bleached hardwood pulp has a tensile index ≥ 50 N·m / g and a bursting index ≥ 5.0 kPa·m. 2 / g, flexural endurance index ≥40 times, brightness ≥88%;

[0134] The bleached softwood pulp has a tensile index ≥ 80 N·m / g and a bursting index ≥ 8.0 kPa·m. 2 / g, flexural endurance index ≥700 times, brightness ≥88%;

[0135] The chemimechanical pulp has a freeness of 300, a brightness of 75%, a bulk of >2.0 cm3 / g, a tensile index ≥30 N.m / g, a fiber bundle content <0.10%, and a pH value of 6.0-8.0.

[0136] The raw materials for the chemical pulp are a combination of poplar, eucalyptus and acacia, wherein the mass ratio of poplar, eucalyptus and acacia is 1:2:3.

[0137] The waste paper is pulp after being decomposed, screened, and refined by the waste paper treatment system;

[0138] The sizing agent used in the surface slurry is ASA sizing agent + aluminum sulfate + rosin; wherein, the oven-dry dosage of ASA sizing agent is 1 kg / ton of paper, the dosage of aluminum sulfate is 10 kg / ton of paper, and the oven-dry dosage of rosin is 10 kg / ton of paper.

[0139] The sizing agent used in the lining slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 10 kg / ton of paper, and the amount of rosin in the oven-dry state is 20 kg / ton of paper.

[0140] The sizing agent used in the core layer slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 15 kg / ton of paper, and the amount of rosin is 30 kg / ton of paper when dry.

[0141] The sizing agent used in the bottom slurry is ASA sizing agent, and the oven-dry dosage of ASA sizing agent is 2 kg / ton of paper.

[0142] The composite step involves combining the surface layer slurry, the lining slurry, the core layer slurry, and the bottom layer slurry.

[0143] The surface sizing step uses a combination of enzymatically hydrolyzed starch solution and styrene-acrylic surface sizing agent, wherein the oven-dry amount of enzymatically hydrolyzed starch solution is 30 kg / ton of paper, and the amount of acrylic surface sizing agent stock solution is 4 kg / ton of paper.

[0144] The acrylic surface sizing agent is manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0145] The surface sizing step involves enzymatically hydrolyzing the original starch with α-amylase at a controlled temperature of 80°C for 20 minutes to obtain cooked starch. This starch is then diluted to a concentration of 16% solids and pumped to the feeding trough of the feeding station. After the styrene-acrylic surface sizing agent is introduced into the pump inlet of the feeding trough, the surface sizing solution is filled into the fabric chamber of the film transfer sizing machine through a pump and a filter screen. A layer of surface sizing solution is then uniformly coated onto the surface of the sizing roller using a metering rod. Finally, the surface sizing solution is uniformly coated onto the paper surface through the squeezing action of the sizing roller, thus completing the film transfer sizing.

[0146] The surface sizing machine has a linear pressure of 30 KN / m; the sizing amount per side of the paper is 4 g / m. 2 The temperature of the surface adhesive solution is 65℃;

[0147] The post-drying step involves passing the paper sheet through a single-mounted cylinder and then through a double-mounted cylinder. Following the cylinder temperature curve, the bound water in the paper sheet is evaporated, drying it to the required process values. A paper stabilizer is installed in the bag area between the cylinders to stabilize the paper web's movement. A sealed hood carries the evaporated moisture out of the hood via hot air, and the heat is recovered through a heat recovery system. After drying in the drying section, the moisture content of the pre-drying paper sheet is controlled at 6.5%.

[0148] Evaporating and removing the bound moisture in the paper sheet can achieve the required paper dryness and give the paper sheet suitable physical strength indicators. In the post-drying process, a paper stabilizer is used to stabilize the paper web running, improve the paper machine operating efficiency, and reduce paper breakage waste. At the same time, a closed air hood is used to reduce heat loss, recover heat energy, improve evaporation efficiency, and reduce the consumption of fresh steam.

[0149] The basis weight of the base paper obtained after the post-drying step is 235 g / m³. 2 The surface smoothness is 8s, the surface roughness is 4.42μm, and the Cobb value (60s) is 21g / m². 2 The Cobb value (60s) on the reverse side is 23 g / m³. 2 ;

[0150] In the hard calendering step, the paper sheet undergoes surface calendering and cross-width thickness modification treatment by a hard calendering machine before coating; the hard calendering line pressure is designed to be within the range of 90kN / m, and the lower roll temperature is 180℃.

[0151] After hard calendering, the paper surface smoothness is improved, which facilitates the subsequent doctor blade coating process. The paper thickness is more uniform in the transverse direction, which improves the subsequent rewinding and slitting and the performance for later customer use.

[0152] The hard calender improves the paper pressing effect by heating the lower roller; it also enables controllable zoning of the upper roller, and the local position can be adjusted according to the paper thickness detection data to achieve a base paper with uniform width thickness.

[0153] The coating process is divided into a first coating, a second coating, a third coating, and a fourth coating.

[0154] The first coating is a pre-coating on the front side, which is done by a doctor blade coating. Specifically, the coating liquid is sprayed evenly onto the paper surface, and then the doctor blade is used to scrape a coating of uniform thickness and basis weight onto the paper surface. The coating is then dried non-contactly by hot air drying, with the hot air drying temperature controlled at 380°C. Finally, the coating is dried in a conditioning cylinder to correct paper warping.

[0155] The composition of the first coating liquid, by weight, includes: 100 parts acrylic emulsion, 30 parts mineral emulsion, and 15 parts wax emulsion.

[0156] The minerals are composed of kaolin, talc powder, and mica powder in a 1:1:1 ratio; the wax emulsion is composed of polyethylene oxide wax with a solid content of 40%.

[0157] The first coating has a liquid-solid content of 50% and a coating weight of 10 g / m². 2 ;

[0158] The second coating is a first functional coating applied to the front side, and the coating method is curtain coating;

[0159] The second coating involves applying the first functional coating on the front side of the paper. The functional coating is uniformly coated onto the paper surface using a curtain coating method. After coating, the coating undergoes non-contact drying with hot air at a controlled temperature of 350°C, followed by non-contact cooling with cold air at a controlled temperature of 30°C. Finally, the paper warping is calibrated using a conditioning cylinder.

[0160] The second coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0161] The second coating solution has a solid content of 50% and a coating weight of 8 g / m². 2 ;

[0162] The third coating is a pre-coating on the reverse side, and the coating method is spray-type blade coating.

[0163] The third coating involves spraying the coating liquid evenly onto the paper surface, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. The coating is then dried non-contactly with hot air, with the temperature controlled at 360°C. After drying to the process set dryness, it is further dried in a conditioning cylinder to address paper warping issues.

[0164] The composition of the third coating liquid, by weight, includes: 100 parts acrylic emulsion, 50 parts mineral emulsion, and 20 parts wax emulsion.

[0165] The minerals are composed of kaolin, talc powder, and mica powder in a 1:1:1 ratio; the wax emulsion is composed of paraffin wax, microcrystalline wax, carnauba wax, polyethylene oxide wax, and polyethylene wax in a 1:2:1:2:3 ratio, with a solid content of 30%.

[0166] The third coating solution has a solid content of 50% and a coating weight of 12 g / m². 2 ;

[0167] The fourth coating is the first functional coating on the reverse side, and the coating method is spray-type blade coating.

[0168] The fourth coating process involves uniformly spraying the coating liquid onto the back of the paper, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. After coating, the coating undergoes non-contact drying with hot air at a controlled temperature of 350°C. Once the dryness is set to the process limit, it is cooled by non-contact cold air drying at a controlled temperature of 30°C. Finally, the paper is calibrated using a conditioning cylinder to address any warping issues.

[0169] The fourth coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0170] The fourth coating solution has a solid content of 50% and a coating weight of 6 g / m². 2 .

[0171] In the soft calendering step, the coated base paper is fed into a soft calendering machine to perform calendering finishing treatment on the coating; the soft calendering line pressure is 70KN / m, and the roller surface temperature is 140℃;

[0172] After soft calendering, the smoothness of the paper coating and the PPS index are improved, which makes it easier to improve the subsequent printing quality for customers.

[0173] The winding process controls the paper temperature within a range of 35°C, employs constant tension winding control, and ensures constant tension and consistent tightness of the master roll.

[0174] Three paper samples were taken from the waterproof and oil-resistant coated cardboard prepared in this embodiment, namely paper sample 1, paper sample 2, and paper sample 3. The Cobb value (60s) of the front side of paper sample 1 is 2.5 g / m³. 2 The Cobb value (60s) on the reverse side is 2.3 g / m³. 2 The kit value on the front is 12, and the kit value on the back is 12; the Cobb value (60s) on the front of pattern 2 is 2.3 g / m². 2 The Cobb value (60s) on the reverse side is 2.6 g / m³. 2 The kit value is 12 on both the front and back sides; the Cobb value (60s) on the front of pattern 1 is 2.7 g / m². 2 The Cobb value (60s) on the reverse side is 2 g / m³. 2 The kit value is 12 on the front and 12 on the back.

[0175] Example 3

[0176] This embodiment provides a method for preparing waterproof and oil-resistant coated cardboard, including the following steps: pulping step, wire-on dewatering step, lamination step, pressing step, pre-drying step, surface sizing step, post-drying step, hard calendering step, coating step, soft calendering step, and winding step.

[0177] The pulping process is divided into pulping of the surface layer pulp, the lining pulp, the core layer pulp, and the bottom layer pulp;

[0178] The composition of the surface layer slurry is: 30% bleached hardwood pulp + 70% bleached softwood pulp;

[0179] The composition of the lining slurry is: 30% bleached softwood pulp + 70% chemimechanical pulp;

[0180] The core pulp composition is: 20% bleached softwood pulp + 60% chemimechanical pulp + 20% waste paper;

[0181] The composition of the underlying pulp is: 30% bleached hardwood pulp + 70% bleached softwood pulp;

[0182] The bleached hardwood pulp has a tensile index ≥ 50 N·m / g and a bursting index ≥ 5.0 kPa·m. 2 / g, flexural endurance index ≥40 times, brightness ≥88%;

[0183] The bleached softwood pulp has a tensile index ≥ 80 N·m / g and a bursting index ≥ 8.0 kPa·m. 2 / g, flexural endurance index ≥700 times, brightness ≥88%;

[0184] The chemimechanical pulp has a freeness of 300, a brightness of 75%, a bulk of >2.0 cm3 / g, a tensile index ≥30 N.m / g, a fiber bundle content <0.10%, and a pH value of 6.0-8.0.

[0185] The raw materials for the chemical pulp are a combination of poplar, eucalyptus and acacia, wherein the mass ratio of poplar, eucalyptus and acacia is 1:2:3.

[0186] The waste paper is pulp after being decomposed, screened, and refined by the waste paper treatment system;

[0187] The sizing agent used in the surface slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 15 kg / ton of paper, and the amount of rosin in the oven-dry state is 25 kg / ton of paper.

[0188] The sizing agent used in the lining slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 10 kg / ton of paper, and the amount of rosin in the oven-dry state is 20 kg / ton of paper.

[0189] The sizing agent used in the core layer slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 15 kg / ton of paper, and the amount of rosin is 30 kg / ton of paper when dry.

[0190] The sizing agent used in the bottom slurry is aluminum sulfate + rosin; wherein, the amount of aluminum sulfate is 20 kg / ton of paper, and the amount of rosin is 30 kg / ton of paper when dry.

[0191] The composite step involves combining the surface layer slurry, the lining slurry, the core layer slurry, and the bottom layer slurry.

[0192] The surface sizing step uses a combination of enzymatically hydrolyzed starch solution and AKD sizing agent, wherein the oven-dry amount of enzymatically hydrolyzed starch solution is 50 kg / ton of paper, and the amount of AKD sizing agent concentrate is 8 kg / ton of paper.

[0193] The AKD sizing agent was provided by Weifang Tianfang Shenghong Chemical Co., Ltd., and its model is SA-301.

[0194] The surface sizing step involves enzymatically hydrolyzing the original starch with α-amylase at a controlled temperature of 90°C for 25 minutes to obtain cooked starch. This starch is then diluted to a concentration of 20% solids and pumped to the feeding trough of the feeding station. After the styrene-acrylic surface sizing agent is introduced into the pump inlet of the feeding trough, the surface sizing solution is filled into the fabric chamber of the film transfer sizing machine through a pump and a filter screen. A layer of surface sizing solution is then uniformly coated onto the surface of the sizing roller using a metering rod. Finally, the surface sizing solution is uniformly coated onto the paper surface through the squeezing action of the sizing roller, thus completing the film transfer sizing.

[0195] The surface sizing machine has a linear pressure of 30 KN / m; the sizing amount per side of the paper is 8 g / m. 2 The temperature of the surface adhesive solution is 70℃;

[0196] The post-drying step involves passing the paper sheet through a single-mounted cylinder and then through a double-mounted cylinder. Following the cylinder temperature curve, the bound water in the paper sheet is evaporated, drying it to the required process values. A paper stabilizer is installed in the bag area between the cylinders to stabilize the paper web's movement. A sealed hood carries the evaporated moisture out of the hood via hot air, and the heat is recovered through a heat recovery system. After drying in the drying section, the moisture content of the pre-drying paper sheet is controlled at 7.5%.

[0197] Evaporating and removing the bound moisture in the paper sheet can achieve the required paper dryness and give the paper sheet suitable physical strength indicators. In the post-drying process, a paper stabilizer is used to stabilize the paper web running, improve the paper machine operating efficiency, and reduce paper breakage waste. At the same time, a closed air hood is used to reduce heat loss, recover heat energy, improve evaporation efficiency, and reduce the consumption of fresh steam.

[0198] The basis weight of the base paper obtained after the post-drying step is 300 g / m³. 2 The surface smoothness is 7s, the surface roughness is 4.38μm, and the Cobb value (60s) is 23g / m². 2The Cobb value (60s) on the reverse side is 22 g / m³. 2 ;

[0199] In the hard calendering step, the paper sheet undergoes surface calendering and cross-width thickness modification treatment by a hard calendering machine before coating; the hard calendering line pressure is designed to be within the range of 110 kN / m, and the lower roller temperature is 200℃.

[0200] After hard calendering, the paper surface smoothness is improved, which facilitates the subsequent doctor blade coating process. The paper thickness is more uniform in the transverse direction, which improves the subsequent rewinding and slitting and the performance for later customer use.

[0201] The hard calender improves the paper pressing effect by heating the lower roller; it also enables controllable zoning of the upper roller, and the local position can be adjusted according to the paper thickness detection data to achieve a base paper with uniform width thickness.

[0202] The coating process is divided into a first coating, a second coating, a third coating, and a fourth coating.

[0203] The first coating is a pre-coating on the front side, which is done by a doctor blade coating. Specifically, the coating liquid is sprayed evenly onto the paper surface, and then the doctor blade is used to scrape a coating with uniform thickness and basis weight on the paper surface. The coating is then dried non-contactly by hot air drying, with the hot air drying temperature controlled at 420°C. Finally, the coating is dried in a conditioning cylinder to correct paper warping.

[0204] The first coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is imPress™ ST-737;

[0205] The first coating has a liquid-solid content of 50% and a coating weight of 10 g / m². 2 ;

[0206] The second coating is a first functional coating applied to the front side, and the coating method is curtain coating;

[0207] The second coating involves applying the first functional coating on the front side of the paper. The functional coating is uniformly coated onto the paper surface using a curtain coating method. After coating, the coating undergoes non-contact drying with hot air at a controlled temperature of 400°C, followed by non-contact cooling with cold air at a controlled temperature of 25°C. Finally, the paper warping is calibrated using a conditioning cylinder.

[0208] The second coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0209] The second coating solution has a solid content of 50% and a coating weight of 12 g / m². 2 ;

[0210] The third coating is a pre-coating on the reverse side, and the coating method is spray-type blade coating.

[0211] The third coating involves spraying the coating liquid evenly onto the paper surface, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. The coating is then dried non-contactly with hot air, with the temperature controlled at 360°C. After drying to the process set dryness, it is further dried in a conditioning cylinder to address paper warping issues.

[0212] The third coating liquid is a finished coating liquid, manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is imPress™ ST-737;

[0213] The third coating solution has a solid content of 50% and a coating weight of 12 g / m². 2 ;

[0214] The fourth coating is the first functional coating on the reverse side, and the coating method is spray-type blade coating.

[0215] The fourth coating process involves uniformly spraying the coating liquid onto the back of the paper, then scraping it onto the paper surface with a doctor blade to create a coating of uniform thickness and basis weight. After coating, the coating undergoes non-contact drying with hot air, controlling the temperature at 400°C. After drying to the process set dryness, it is then cooled by non-contact cold air drying, controlling the temperature at 25°C. Finally, the paper warping is calibrated using a conditioning cylinder.

[0216] The fourth coating liquid, by weight, comprises: 100 parts acrylic emulsion, 30 parts mineral emulsion, and 15 parts wax emulsion.

[0217] The minerals are composed of kaolin, talc powder, and mica powder in a 1:1:1 ratio; the wax emulsion is composed of polyethylene oxide wax with a solid content of 40%.

[0218] The fourth coating layer has a liquid-solid content of 50% and a coating weight of 10 g / m². 2 ;

[0219] The fifth coating is a second functional coating on the front side, applied by spray-type doctor blade coating. The functional coating material is applied to the front side of the paper for a second functional coating, giving the paper special functional requirements. After the coating liquid is evenly sprayed onto the paper surface, a doctor blade is used to scrape a coating of uniform thickness and basis weight onto the paper surface. After coating, the coating is dried by hot air drying in a non-contact manner, with the hot air drying temperature controlled at 400℃. After drying to the process set dryness, it is cooled by non-contact cold air drying, with the cold air drying temperature controlled at 25℃. Finally, the paper warping problem is calibrated by a conditioning cylinder.

[0220] The fifth coating liquid is manufactured by Solis (Shanghai) Chemical Co., Ltd., and its model is Basoplast™ 8903AP;

[0221] The fifth coating has a liquid-solid content of 50% and a coating weight of 4 g / m². 2 ;

[0222] In the soft calendering step, the coated base paper is fed into a soft calendering machine to perform calendering and finishing treatment on the coating; the soft calendering line pressure is 110KN / m, and the roller surface temperature is 150℃;

[0223] After soft calendering, the smoothness of the paper coating and the PPS index are improved, which makes it easier to improve the subsequent printing quality for customers.

[0224] The winding process controls the paper temperature within a range of 30°C, employs constant tension winding control, and ensures constant tension and consistent tightness of the master roll.

[0225] Three paper samples were taken from the waterproof and oil-resistant coated cardboard prepared in this embodiment, namely paper sample 1, paper sample 2, and paper sample 3. The Cobb value (60s) of the front side of paper sample 1 is 0.2 g / m. 2 The Cobb value (60s) on the reverse side is 0.3 g / m³. 2 The kit value on the front is 12, and the kit value on the back is 12; the Cobb value (60s) on the front of pattern 2 is 0 g / m. 2 The Cobb value (60s) on the reverse side is 0.4 g / m³. 2 The kit value is 12 on both the front and back sides; the Cobb value (60s) on the front side of pattern 1 is 0.1 g / m². 2 The Cobb value (60s) on the reverse side is 0.2 g / m³. 2 The kit value is 12 on the front and 12 on the back.

[0226] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A method for producing a water- and oil-repellent coated paper, characterized by, It comprises the following steps: a beating step, a wire dewatering step, a compounding step, a pressing step, a pre-drying step, a surface sizing step, a post-drying step, a hard calendering step, a coating step, a soft calendering step, and a winding step; the surface sizing agent used in the surface sizing step is a combination of an enzymatic starch solution and a base surface sizing agent; the base surface sizing agent is one or more of a styrene-acrylic surface sizing agent, an acrylic surface sizing agent, and an AKD sizing agent; the coating step is divided into a first coating, a second coating, a third coating, and a fourth coating; the first coating uses a spraying doctor blade to pre-coat the front side of the paper, and the coating liquid is sprayed onto the paper surface, and then the coating layer with uniform thickness and basis weight is scraped off by the doctor blade, and then the coating layer is dried by hot air drying for non-contact drying, with the hot air drying temperature controlled at 300-420℃, and then a conditioning cylinder is used to dry and correct the paper curling problem; the first coating liquid is one of a finished coating liquid or a self-made coating liquid; when the first coating liquid is a finished coating liquid, the production manufacturer of the finished coating liquid is Solvay Chemical Co., Ltd., and the model is imPress™ ST-737; when the first coating liquid is a self-made coating liquid, the composition of the self-made coating liquid, by weight, comprises: 100 parts of acrylic emulsion, 0-50 parts of mineral, and 0-20 parts of wax emulsion; the second coating is the first functional coating on the front side of the paper, and the functional coating is applied on the paper surface by curtain coating to form a uniform functional barrier coating, and then the coating layer is dried by hot air drying for non-contact drying, with the hot air drying temperature controlled at 280-400℃, and then the coating layer is cooled by non-contact cold air drying, with the cold air drying temperature controlled at 25-35℃, and finally the conditioning cylinder is used to correct the paper curling problem; the second coating liquid is a finished coating liquid, and the production manufacturer is Solvay Chemical Co., Ltd., and the model is Basoplast™ 8903AP; the third coating uniformly sprays the coating liquid onto the paper surface, and then the coating layer with uniform thickness and basis weight is scraped off by the doctor blade, and then the coating layer is dried by hot air drying for non-contact drying, with the hot air drying temperature controlled at 320-360℃, and then the conditioning cylinder is used to further dry and correct the paper curling problem after drying to the process set dryness; the third coating liquid is one of a finished coating liquid or a self-made coating liquid; when the third coating liquid is a finished coating liquid, the production manufacturer of the finished coating liquid is Solvay Chemical Co., Ltd., and the model is imPress™ ST-737; when the third coating liquid is a self-made coating liquid, the composition of the self-made coating liquid, by weight, comprises: 100 parts of acrylic emulsion, 0-50 parts of mineral, and 0-20 parts of wax emulsion. The fourth coating, the coating liquid is uniformly sprayed to the back of the paper, and then the thickness and the uniformity of the coating layer are scraped by the scraper, after the coating, the coating layer is dried by hot air for non-contact drying, the temperature of the hot air drying is controlled at 280-400℃, after drying to the process setting dryness, the coating layer is cooled by non-contact cold air drying, the temperature of the cold air drying is controlled at 25-35℃, and then the calibration of the paper page warping problem is carried out by the conditioning cylinder; The fourth coating liquid is one of the finished coating liquid or the self-made coating liquid; When the fourth coating liquid is the finished coating liquid, the production manufacturer of the finished coating liquid is Solvay Chemical Industry Co., Ltd., and the model is BasoplastTM 8903AP; When the fourth coating liquid is the self-made coating liquid, the composition of the self-made coating liquid includes, by weight: 100 parts of acrylic emulsion, 0-50 parts of mineral, and 0-20 parts of wax emulsion; The fifth coating is the second functional coating on the front side, the coating method is spraying scraper coating, the functional coating is coated on the front side of the paper for the second time, the coating liquid is uniformly sprayed to the paper, and then the thickness and the uniformity of the coating layer are scraped by the scraper, after the coating, the coating layer is dried by hot air for non-contact drying, the temperature of the hot air drying is controlled at 200-450℃, after drying to the process setting dryness, the coating layer is cooled by non-contact cold air drying, the temperature of the cold air drying is controlled at 25-35℃, and then the calibration of the paper page warping problem is carried out by the conditioning cylinder.

2. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The beating step is divided into surface layer pulp, lining layer pulp, core layer pulp and bottom layer pulp; The composition of the surface layer pulp is: 0-30% bleached broadleaf wood pulp + 70-100% bleached coniferous wood pulp; The composition of the lining layer pulp is: 15-30% bleached coniferous wood pulp + 70-85% chemi-mechanical pulp; The composition of the core layer pulp is: 0-30% bleached coniferous wood pulp + 70-100% chemi-mechanical pulp + 0-20% broke paper; The composition of the bottom layer pulp is: 0-50% bleached broadleaf wood pulp + 50-100% bleached coniferous wood pulp; The raw material of the chemi-mechanical pulp is one or more of poplar, eucalyptus and acacia; The pulp of the broke paper after the broke paper treatment system is loosened, screened and milled.

3. The method of producing a water and oil repellent coated paper according to claim 2, characterized by, The pulp internal sizing agent used in the surface layer, lining layer, core layer and bottom layer is one or more of ASA sizing agent, aluminum sulfate and rosin sizing agent; The absolute dry amount of the ASA sizing agent is 1-8 kg / ton of paper; The amount of aluminum sulfate is 10-30 kg / ton of paper; The absolute dry amount of the rosin sizing agent is 10-30 kg / ton of paper; The compounding step is to compound the surface layer pulp, the lining layer pulp, the core layer pulp and the bottom layer pulp.

4. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The absolute dry amount of the enzymatic starch liquid used in the surface sizing step is 10-50 kg / ton of paper; When the basic surface sizing agent is a phenylpropyl surface sizing agent, the amount of the raw solution of the phenylpropyl surface sizing agent is 2-4 kg / ton of paper; When the basic surface sizing agent is an acrylic surface sizing agent, the amount of the raw solution of the acrylic surface sizing agent is 2-4 kg / ton of paper; When the base surface sizing agent is AKD sizing agent, the dosage of the AKD sizing agent stock solution is 2-10 kg / ton of paper; The preparation method of the surface sizing agent is as follows: original starch is subjected to enzymolysis by an alpha-amylase, the enzymolysis temperature is controlled to be 65-95 DEG C, and the enzymolysis time is controlled to be 10-30 min, so as to obtain cooked starch; the cooked starch is diluted to a concentration of 12%-20% solid content, pumped to a feeding tank of a feeding station, and after adding a suitable ratio of the surface sizing agent at the pump inlet of the feeding tank, the starch sizing solution is filled in a cloth transfer sizing machine through a pump and a filter screen, and a layer of the starch sizing solution is uniformly coated on the surface of a sizing roller through a metering rod, and then the starch sizing solution is uniformly coated on the surface of the paper sheet through the extrusion of the sizing roller, so as to complete the film transfer sizing; The line pressure of the sizing machine is 20-40 KN / m, and the single-side sizing amount of the paper sheet is 2-8 g / m 2 The temperature of the sizing liquid is 50-70℃.

5. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The post-drying step is as follows: the paper sheet is subjected to a single cylinder, then subjected to a double cylinder, and then subjected to a drying cylinder temperature curve, so as to evaporate the combined water in the paper sheet, and dry the paper sheet to a process requirement value; a bag area between the drying cylinders is provided with a paper stabilizer to stabilize the running of the paper web; The hard calendering step is as follows: the paper sheet is subjected to surface calendering and cross profile thickness modification treatment by a hard calendering machine before coating; the hard calendering line pressure is 10-120 KN / m, and the lower roller temperature is 140-200 DEG C.

6. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The first coating is pre-coating on the front side by using a doctor blade coating method; The second coating is the first functional coating on the front side by using a curtain coating method; The third coating is pre-coating on the back side by using a spraying doctor blade coating method; The fourth coating is the first functional coating on the back side by using a spraying doctor blade coating method.

7. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, When the first coating liquid is a self-made coating liquid, the composition of the self-made coating liquid contains one or more of kaolin, talcum powder and mica powder; The composition of the wax emulsion contains one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene oxide wax and polyethylene wax, and the solid content is 20-60%; The solid content of the first coating liquid is 30-70%, and the coating amount is 6-15 g / m 2 ; The solid content of the second coating liquid is 30-70%, and the coating amount is 6-15 g / m 2 ; When the third coating liquid is a self-made coating liquid, the composition of the self-made coating liquid contains one or more of kaolin, talcum powder and mica powder; The composition of the wax emulsion contains one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene oxide wax and polyethylene wax, and the solid content is 20-60%; The solid content of the third coating liquid is 30-70%, and the coating amount is 6-15 g / m 2 ; When the fourth coating liquid is a self-made coating liquid, the composition of the self-made coating liquid contains one or more of kaolin, talcum powder and mica powder; The composition of the wax emulsion contains one or more of paraffin wax, microcrystalline wax, carnauba wax, polyethylene oxide wax and polyethylene wax, and the solid content is 20-60%; The solid content of the fourth coating liquid is 30-70%, and the coating amount is 6-15 g / m 2 .

8. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The coating step further includes a fifth coating; The fifth coating liquid is produced by SOKOAN CO., LTD., and the model is BasoplastTM 8903AP; The fifth coating liquid has a solid content of 30-70% and a coating amount of 4-10 g / m 2 .

9. The method of producing a water and oil repellent coated paper according to claim 1, characterized by, The soft calendering step is as follows: the coated base paper is added to a soft calendering machine, and the coating layer is subjected to calendering modification treatment; the soft calendering line pressure is 20-120 KN / m, and the roller surface temperature is 120-160 DEG C. The winding is as follows: the temperature of the paper sheet is controlled to be in the range of 30-50 DEG C, constant tension winding control is performed, the parent roller tension is constant, and the tightness is consistent.