Aqueous coated fine paper and method for its production

Abstract

The application discloses a kind of water-based coating framing paper and preparation method thereof, the water-based coating framing paper of the application, including base paper and water-based slurry coating on the one side of base paper;Water-based slurry coating is printed with water-based ink layer, and there is recessed surface and protruding surface after embossing on water-based ink layer and water-based slurry layer.The water-based coating framing paper of the application is uniform, with the skin texture paper.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a water-based coated binding paper and its preparation method. Background Technology

[0002] Currently, imitation leather binding and packaging coated paper generally uses a PVC coating combined with water-based inks, relying on the PVC foam layer to achieve the embossed imitation leather effect, and its application is widespread. PVC coating production requires high-temperature plasticization, resulting in high energy consumption; the plasticizers in the system are prone to volatilization and migration during high-temperature processing and long-term use. Furthermore, the migration of plasticizers easily forms an oil film on the coating surface, causing the finished product to gradually become sticky to the touch over long-term use, making it difficult to replicate the dry and warm texture of genuine leather, resulting in a poor leather simulation effect.

[0003] To make bookbinding paper both environmentally friendly and have the feel of genuine leather, the industry urgently needs to develop a method for preparing bookbinding paper to overcome the shortcomings of existing specialty papers, meet the current environmental development needs of low VOC, halogen-free, and biodegradable materials, reduce production energy consumption, reduce VOC emissions during the preparation process, and give the finished product a delicate and realistic leather feel. Summary of the Invention

[0004] Based on improvements to the above-mentioned problems, the present invention provides a water-based coated binding paper and a method for preparing the same.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a water-based coated binding paper, comprising a base paper and a water-based slurry coating applied to one side of the base paper; a water-based ink layer is printed on the water-based slurry coating, and the water-based slurry coating and the water-based ink layer have recessed and raised surfaces.

[0006] Furthermore, the water-based slurry coating comprises the following components by weight: 60 parts of pure acrylic copolymer emulsion, 28-35 parts of white paste, 11-13 parts of foam stabilizer, and 1.8-2.2 parts of crosslinking agent; the water-based slurry coating also includes ammonia and a thickener. Ammonia is a pH adjuster to achieve the set pH value as the addition endpoint; the thickener is a viscosity adjusting component, and its dosage is limited by the final viscosity index of the slurry system, and the actual addition ratio is determined through viscosity closed-loop control.

[0007] Furthermore, the pure acrylate copolymer emulsion is a mixture of pure acrylate copolymer emulsion 358 and pure acrylate copolymer emulsion 351 in parts by weight, with the ratio controlled within the range of 1.5:1 to 2:1.

[0008] Furthermore, the base paper is non-woven paper with a thickness of 0.12mm to 0.16mm, and the thickness of the water-based slurry coating is 0.02mm to 0.36mm.

[0009] Furthermore, the method for preparing the water-based coated bookbinding paper is characterized by comprising the following steps: (1) Add 60 parts of pure acrylic copolymer emulsion, 28-35 parts of white paste, 11-13 parts of foam stabilizer and 1.8-2.2 parts of crosslinking agent to a mixing tank and mix evenly. Add ammonia water dropwise to adjust the pH value to between 8.0 and 9.5. Then add viscosity regulator and stir evenly to form a mixture with a viscosity between 3300 mPa·s and 4000 mPa·s.

[0010] (2) The mixture obtained in step (1) is added to a coating machine and coated on non-woven paper with a thickness of 0.12 mm to 0.16 mm. After drying, printing, embossing, and finally winding, water-based coated binding paper is obtained. The non-woven paper enters the coating machine at a speed of 20 m / min to 35 m / min.

[0011] Furthermore, the coating machine is a rotary screen coating machine, and the mesh size of the rotary screen coating machine is in the range of 105 mesh to 140 mesh. The rotary screen coating machine coats the water-based slurry onto the base paper to form a wet coating of 0.03 mm to 0.40 mm.

[0012] Furthermore, the drying process described in step (2) uses a hot air oven with a length of 3m and a temperature set at 140℃~155℃.

[0013] Furthermore, the printing described in step (2) is done using a flexographic printing press.

[0014] Furthermore, the embossing process described in step (2) adopts a roller-type cold embossing assembly, which is equipped with an upper roller and a bottom roller, and the upper roller is decorated with patterns.

[0015] Furthermore, the bottom roller of the roller-type cold-press embossing assembly is a wool bottom roller.

[0016] This invention prepares water-based coated bookbinding paper with a uniform coating and a leather-like feel by adjusting the formula and process for preparing water-based coated bookbinding paper, including controlling the viscosity range, selecting the mesh number of the rotary screen printing machine, selecting the printing machine and printing ink, and selecting the cold pressing embossing components and bottom roller. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the water-based coated binding paper before embossing according to the present invention.

[0018] Figure descriptions: 1. Base paper; 2. Water-based paste coating; 3. Water-based ink layer. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] The present invention provides a water-based coated binding paper, comprising a base paper 1, one side of which is coated with a water-based slurry coating 2, and a water-based ink layer 3 is printed on the water-based slurry coating 2. After embossing, the water-based ink layer 3 and the water-based slurry coating 2 have certain concave and convex surfaces. Figure 1 It is water-based coated binding paper before embossing.

[0021] The present invention also provides a method for preparing the water-based coated binding paper described in the above technical solution, comprising the following steps: (1) Slurry preparation: Weigh each component of the water-based slurry according to the formula, put them into the mixing tank and mix evenly, add ammonia water in a quantitative manner to adjust the pH value to the specified range, then add viscosity regulator and stir evenly to adjust the viscosity of the water-based slurry to the specified viscosity range.

[0022] (2) Coating: The unwinding frame releases the base paper at a constant linear speed and feeds it into the coating machine at a specified linear speed. The feed pump pressurizes and delivers the aqueous slurry obtained in step (1) into the cylindrical screen, uniformly coating the aqueous slurry onto one side of the base paper. The aqueous slurry forms a continuous wet coating with uniform thickness on the surface of the base paper. The thickness of the wet coating is calculated according to the target dry film thickness.

[0023] (3) Drying: The paper obtained in step (2) is continuously drawn into the hot air oven by the guide roller. Inside the hot air oven, multiple sets of air knives alternately blow high-temperature hot air up and down to dry the wet pulp layer on the paper surface in a segmented gradient. After the moisture has fully evaporated, it is smoothly sent out by the paper output traction roller. The forced convection of hot air carries away the free moisture inside the water-based coating, so that the water-based coating is dehydrated and cured, and the adhesion between the water-based coating and the base paper is enhanced.

[0024] (4) Printing: The paper obtained in step (3) is fed into the printing press by the paper guide roller. The rubber roller of the printing press transfers the ink to the water-based coating surface to form the specified color and pattern.

[0025] (5) Embossing: The paper obtained in step (4) is fed into the embossing assembly after the tension roller stabilizes the paper's flow. The upper and lower rollers of the embossing assembly roll and squeeze against each other to emboss the paper surface, pressing out the preset concave and convex patterns and compacting the coating. The mechanical pressure of the rollers causes the coating to undergo plastic deformation and set, producing concave and convex surfaces in the water-based ink layer and water-based paste coating; at the same time, the coating pores are closed, improving the three-dimensionality of the pattern and the wear resistance of the coating.

[0026] (6) Winding: The paper obtained in step (5) is wound by the winding machine core under constant tension by the tension sensor to obtain a regular roll of water-based coated binding paper.

[0027] In this invention, the base paper is non-woven paper, and the thickness of the base paper is in the range of 0.12mm to 0.16mm.

[0028] In this invention, the preferred slurry formulation is: 60 parts by weight of pure acrylate copolymer emulsion, 28-35 parts by weight of white paste, 11-13 parts by weight of foam stabilizer, and 1.8-2.2 parts by weight of crosslinking agent. The aqueous slurry formulation also includes ammonia and a thickener. Ammonia is a pH adjuster to achieve the set pH value as the addition endpoint; the thickener is a viscosity adjusting component, and its dosage is limited by the final viscosity index of the slurry system, with the actual addition ratio determined through viscosity closed-loop control.

[0029] In this invention, the pure acrylate copolymer emulsion is preferably a mixture of pure acrylate copolymer emulsion 358 and pure acrylate copolymer emulsion 351 in a weight ratio controlled within the range of 1.5:1 to 2:1.

[0030] In this invention, the white paste is a white, high-solids-content mineral pigment water dispersion paste, which is a commercially available conventional raw material. Its main components are heavy calcium carbonate, washed kaolin, titanium dioxide, deionized water, and a small amount of additives.

[0031] In this invention, the foam stabilizer is one of a nonionic surfactant, a polymer colloid, or anionic surfactant, and is particularly preferred to be a fatty acid alkanolamide among nonionic surfactants.

[0032] In this invention, the crosslinking agent is preferably an externally added crosslinking agent, and is particularly preferably one of polycarbodiimide or epoxy silane coupling agent.

[0033] In this invention, the thickener is one of polyurethane thickener, hydroxyethyl cellulose or acrylic thickener, preferably a polyurethane thickener.

[0034] In this invention, the viscosity range of the aqueous slurry is 3300 mPa·s to 4000 mPa·s.

[0035] In this invention, the speed at which the nonwoven paper enters the coating machine is 20 m / min to 35 m / min. The coating machine of this invention is preferably a rotary screen coating machine, wherein the mesh count of the rotary screen ranges from 105 mesh to 140 mesh.

[0036] In this invention, the length of the hot air oven is 3m, the temperature range is 140℃~155℃, and the power of the hot air oven is preferably 233KW.

[0037] In this invention, the printing press is preferably a flexographic printing press, and the water-based ink is preferably one of acrylic water-based ink or PU-modified acrylic water-based ink. The initial coating thickness of the water-based ink formed in this process is relatively low. After embossing, the ink penetrates into the interior of the water-based paste coating, and the ink and the water-based paste coating are tightly bonded. The thickness of the independent thin layer formed by the ink after embossing was not measured separately.

[0038] In this invention, the embossing component is preferably a roll-type cold-press embossing component, the upper roller of the cold-press embossing component is preferably a carved steel upper roller, and the bottom roller is preferably a polyurethane bottom roller or a wool bottom roller, with a wool bottom roller being particularly preferred.

[0039] To further illustrate the present invention, the following embodiments are provided for detailed description. All raw materials used in the following embodiments of the present invention are commercially available products. Example 1

[0040] (1) Weigh the following water-based slurry raw materials according to weight: 40 parts pure acrylate copolymer emulsion 358, 20 parts pure acrylate copolymer emulsion 351, 28 parts white paste, and 12 parts foam stabilizer. After stirring the above water-based slurry evenly, add ammonia to adjust the pH to 8.0, then add 1.9 parts crosslinking agent and an appropriate amount of thickener to adjust the viscosity of the water-based slurry to about 3500 mPa·s.

[0041] (1) The non-woven paper with a thickness of 0.14 mm is fed into the rotary screen coating machine at a linear speed of 25 m / min. The feed pump pressurizes and delivers the water-based slurry obtained in step (1) into the rotary screen cylinder, and the slurry is evenly coated on one side of the base paper to form a continuous wet coating with uniform thickness on the surface of the base paper. The rotary screen mesh number is 125 mesh, and the thickness of the wet coating is controlled to be 0.13 mm.

[0042] (3) The paper obtained in step (2) is continuously pulled into the hot air oven by the guide roller for drying. The hot air oven is 3m long, the temperature is set to 150℃, and the power is 233KW.

[0043] (4) The paper obtained in step (3) is fed into the printing press via the guide roller. The printing press rubber roller transfers the ink onto the water-based coating surface to form the specified color and pattern. The average amount of water-based ink used is 3g / m². 2 .

[0044] (5) The paper obtained in step (4) is fed into the cold pressing embossing assembly after the tension roller stabilizes the paper's flow force. The cold pressing embossing assembly uses a carved steel upper roller and a wool bottom roller.

[0045] (6) The paper obtained in step (5) is wound by the winding machine core under constant tension by the tension sensor to obtain water-based coated binding paper with a thickness of 0.25mm, wherein the non-woven paper thickness is 0.14mm and the water-based pulp coating thickness is 0.11mm. The water-based coated binding paper in this embodiment has a rich color. Example 2

[0046] The difference between this embodiment and Embodiment 1 is that the weight parts of the water-based slurry formulation are: 36 parts of pure acrylic copolymer emulsion 358, 24 parts of pure acrylic copolymer emulsion 351, 35 parts of white pulp, and 12 parts of foam stabilizer. After the water-based slurry is stirred evenly, ammonia is added to adjust the pH value to 9.5, and then 1.9 parts of crosslinking agent and an appropriate amount of thickener are added to adjust the viscosity of the water-based slurry to approximately 3500 mPa·s. The cold pressing embossing assembly uses a carved steel upper roller and a polyurethane bottom roller. This embodiment produces a water-based coated binding paper with a thickness of 0.25 mm, wherein the non-woven paper thickness is 0.14 mm and the water-based coating thickness is 0.11 mm. Example 3

[0047] The difference between this embodiment and Embodiment 1 is as follows: the pH of the water-based slurry is adjusted to 9.0, the crosslinking agent is 2.0 parts, the viscosity is adjusted to 3600 mPa·s, the base paper thickness is 0.12 mm, and the base paper linear speed is 30 m / min; in the coating process, the rotary screen coating machine uses a 140-mesh screen, and the wet coating thickness is 0.10 mm; in the drying process, the hot air oven temperature is set to 145℃. The water-based coated binding paper obtained in this embodiment has a thickness of 0.20 mm, of which the non-woven paper thickness is 0.12 mm and the water-based slurry coating thickness is 0.08 mm. Example 4

[0048] The difference between this embodiment and Embodiment 1 is as follows: the base paper thickness is 0.12 mm, the base paper linear speed is 20 m / min; 11 parts of foam stabilizer, 1.8 parts of crosslinking agent, the viscosity of the water-based slurry is adjusted to 3300 mPa·s, the mesh count of the rotary screen coating machine in the coating process is 105 mesh, and the coating thickness is controlled at 0.40 mm; the temperature of the hot air oven in the drying process is set to 155℃. The thickness of the water-based coated binding paper obtained in this embodiment is 0.52 mm, of which the non-woven paper thickness is 0.12 mm and the water-based slurry coating thickness is 0.36 mm. Example 5

[0049] The difference between this embodiment and Embodiment 1 is as follows: the base paper thickness is 0.16 mm, the base paper linear speed is 35 m / min; 13 parts of foam stabilizer, 2.2 parts of crosslinking agent, the viscosity of the water-based slurry is adjusted to 4000 mPa·s, the mesh count of the rotary screen coating machine in the coating process is 140 mesh, and the wet coating thickness is 0.03 mm; the temperature of the hot air oven in the drying process is set to 140℃. The thickness of the water-based coated binding paper obtained in this embodiment is 0.18 mm, of which the non-woven paper thickness is 0.16 mm and the water-based coating thickness is 0.02 mm. Example 6

[0050] The difference between this embodiment and Embodiment 1 is as follows: the base paper thickness is 0.16 mm, the base paper linear speed is 20 m / min; 11 parts of foam stabilizer, 1.8 parts of crosslinking agent, the viscosity of the water-based slurry is adjusted to 3400 mPa·s, the mesh count of the rotary screen coating machine in the coating process is 105 mesh, and the wet coating thickness is controlled at 0.22 mm; the temperature of the hot air oven in the drying process is set to 155℃. The thickness of the water-based coated binding paper obtained in this embodiment is 0.35 mm, of which the non-woven paper thickness is 0.16 mm and the water-based coating thickness is 0.19 mm. Comparative Example 1

[0051] The difference between this comparative example and Example 1 is that the printing process in this comparative example uses gravure printing, and the average amount of water-based ink used is 3g / m². 2 The color of the finished paper is significantly lighter and less saturated compared to Example 1. Comparative Example 2

[0052] The difference between this comparative example and Example 1 is that the printing process in this comparative example uses gravure printing, and the average amount of water-based ink used is 8g / m². 2 The color of the finished paper is similar to that of Example 1. Comparative Example 3

[0053] The difference between this comparative example and Example 1 is that the coating process in this comparative example uses a doctor blade coater, and the drying process uses a 15m long hot air oven with temperature settings of 120℃, 125℃, and 125℃, and a power of 233KW. This example produces water-based coated binding paper with a thickness of 0.25mm, of which the non-woven paper thickness is 0.14mm and the water-based slurry coating thickness is 0.11mm. Because the hot air oven in the drying process is 15m long, the energy consumption of the drying process is significantly higher than that of Example 1. Comparative Example 4

[0054] This comparative example uses PVC slurry to coat non-woven paper, which is then dried, printed, and embossed to obtain PVC slurry coated paper.

[0055] (1) Weigh the following PVC slurry according to the following weight parts: 340 parts PVC resin powder, 230 parts plasticizer, 350 parts calcium carbonate, 24 parts foaming agent, and 50 parts titanium dioxide. Add viscosity reducer to adjust the viscosity to 1500 mPa·s-2000 mPa·s.

[0056] (2) Feed the base paper with a thickness of 0.14 mm into the scraper coating machine at a linear speed of 45 m / min. Pump the PVC slurry obtained in step (2) into the scraper coating machine. The scraper coating machine coats the PVC slurry onto the base paper. The thickness of the PVC wet coating is controlled to be 0.12 mm.

[0057] (3) The paper obtained in step (2) is fed into a hot air oven. The hot air oven in this comparative example is a three-section hot air oven with a total length of 15m. The temperature settings are 175℃, 195℃ and 192℃ respectively, and the power is 233KW.

[0058] (4) Feed the paper obtained in step (3) into a gravure printing press and print the PVC coating with water-based ink. The average amount of water-based ink used is 2 g / m. 2 .

[0059] (5) Feed the paper obtained in step (4) into the hot pressing embossing assembly. The hot pressing embossing assembly uses a carved steel upper roller and a silicone rubber bottom roller. The temperature of the hot pressing embossing assembly is set to 200℃.

[0060] (6) The paper obtained in step (5) is wound by the winding machine core under constant tension by the tension sensor to obtain PVC coated paper with a thickness of 0.25mm, of which the non-woven paper thickness is 0.14mm and the PVC pulp layer thickness is 0.11mm.

[0061] Thickness tests, appearance quality evaluations, and faux leather feel tests were performed on the products corresponding to Examples 1-6 and Comparative Examples 1-4. The testing methods are as follows: 1. Thickness test: Tested according to GB / T 451.3-2026 "Paper and paperboard - Part 3: Determination of thickness", taking 10 points and calculating the average value.

[0062] 2. Appearance quality evaluation: Evaluate the coating surface and embossed appearance in accordance with GB / T 10335.1-2017 Coated Paper and Paperboard Coated Art Printing Paper.

[0063] 3. Imitation leather feel test: 3 inspectors conducted a blind test, requiring the leather to feel soft and elastic, with a smooth and non-gritty surface, and a sufficiently three-dimensional embossed texture to meet the requirements of imitation leather feel.

[0064] The test results are shown in Table 1.

[0065] From the test results and color saturation of Example 1, Comparative Example 1, and Comparative Example 2, it can be seen that, under the same ink formulation and average usage conditions, the water-based coated binding paper printed using flexographic printing has a deeper color than the water-based coated binding paper printed using gravure printing. To achieve the same color saturation for the water-based coated binding paper, the average ink usage for gravure printing is approximately 2.7 times that of flexographic printing. Comparative Example 2 shows slight blurring at the printing edges, which is analyzed to be caused by the larger ink usage in gravure printing and the lateral diffusion of ink during embossing.

[0066] As can be seen from the test results and production process of Example 1 and Comparative Example 3, the water-based slurry of the present invention can be coated onto the base paper using a doctor blade coating machine. The length of the hot air oven required for drying the coating using a doctor blade coating machine is 15m, which is 12m longer than the 3m hot air oven for drying the coating using a rotary screen coating machine. The drying energy consumption is significantly higher than that of the rotary screen coating machine.

[0067] The test results from Example 1 and Comparative Example 4 show that the feel of PVC coated paper differs somewhat from that of leather. After a period of time, the plasticizer in the PVC coated paper slowly leaches out, resulting in a sticky surface. During the production of PVC coated paper, the length and temperature of the hot air oven are higher than in Example 1, and the energy consumption of the hot-press embossing assembly is significantly higher than that of the cold-press embossing assembly used in Example 1. After multiple implementations and statistical analysis, the average energy consumption of PVC coated paper production is twice that of water-based coated binding paper. PVC pulp typically contains more than 20% plasticizer by weight. The plasticizer volatilizes to some extent during the drying and embossing processes, resulting in significantly higher VOC emissions than water-based coated binding paper.

[0068] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-based coated binding paper, characterized in that, It includes base paper and an aqueous slurry coating applied to one side of the base paper; an aqueous ink layer is printed on the aqueous slurry coating, and the aqueous slurry coating and the aqueous ink layer have recessed and raised surfaces.

2. The water-based coated binding paper according to claim 1, characterized in that, The water-based slurry coating comprises the following components by weight: 60 parts of pure acrylic copolymer emulsion, 28-35 parts of white paste, 11-13 parts of foam stabilizer, and 1.8-2.2 parts of crosslinking agent. The water-based slurry coating also includes ammonia and a thickener. Ammonia is a pH adjuster to achieve the set pH value as the addition endpoint. The thickener is a viscosity adjusting component, and its dosage is limited by the final viscosity index of the slurry system. The actual addition ratio is determined through viscosity closed-loop control.

3. The water-based coated binding paper according to claim 2, characterized in that, The pure acrylate copolymer emulsion is a mixture of pure acrylate copolymer emulsion 358 and pure acrylate copolymer emulsion 351 in parts by weight, with the ratio controlled within the range of 1.5:1 to 2:

1.

4. The water-based coated binding paper according to claim 3, characterized in that, The base paper is non-woven paper with a thickness of 0.12mm to 0.16mm, and the thickness of the water-based slurry coating is 0.02mm to 0.36mm.

5. The method for preparing water-based coated binding paper according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Add 60 parts by weight of pure acrylic copolymer emulsion, 28-35 parts by weight of white paste, 11-13 parts by weight of foam stabilizer, and 1.8-2.2 parts by weight of crosslinking agent to a mixing tank and mix evenly. Add ammonia water dropwise to adjust the pH value to between 8.0 and 9.

5. Then add viscosity modifier and stir evenly to form a mixture with a viscosity between 3300 mPa·s and 4000 mPa·s. (2) The mixture obtained in step (1) is added to a coating machine and coated on non-woven paper with a thickness of 0.12 mm to 0.16 mm. After drying, printing, embossing, and finally winding, water-based coated binding paper is obtained. The non-woven paper enters the coating machine at a speed of 20 m / min to 35 m / min.

6. The method for preparing water-based coated binding paper according to claim 5, characterized in that, The coating machine is a rotary screen coating machine, and the mesh size of the rotary screen coating machine is in the range of 105 mesh to 140 mesh. The rotary screen coating machine coats the water-based slurry onto the base paper to form a wet coating of 0.03 mm to 0.40 mm.

7. The method for preparing water-based coated binding paper according to claim 5, characterized in that, The drying process described in step (2) uses a 3m long hot air oven with a temperature set at 140℃~155℃.

8. The method for preparing water-based coated binding paper according to claim 5, characterized in that, The printing described in step (2) is done using a flexographic printing press.

9. The method for preparing water-based coated binding paper according to claim 5, characterized in that, The embossing process described in step (2) uses a roller-type cold embossing assembly. The cold embossing assembly is equipped with an upper roller and a bottom roller, and the upper roller is decorated with patterns.

10. The method for preparing water-based coated binding paper according to claim 9, characterized in that, The bottom roller of the roller-type cold pressing embossing assembly is a wool bottom roller.

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