Decorative paper production process based on water-based ink gravure printing

Abstract

The present invention discloses a decorative paper production process based on water-based ink gravure printing, and belongs to the technical field of decorative paper production. The decorative paper production process based on water-based ink gravure printing comprises the following steps: S1 pretreatment: the base paper is subjected to a water process by roller coating to obtain a wet base paper; S2 drying: the wet base paper is subjected to mirror roller drying to obtain a dry paper; S3 gravure printing: the configured water-based ink is added to the ink tank of a gravure printing machine, and the dry paper is mounted on the gravure printing machine for gravure printing to obtain gravure printing paper; S4 drying: the gravure printing paper is dried and rolled to obtain a decorative paper based on water-based ink gravure printing. The water-based ink gravure printing decorative paper prepared by the present invention has good adhesion, and at the same time, the aging resistance is enhanced, thereby extending the service life of the decorative paper.

Description

Technical Field

[0001] The invention relates to the technical field of decorative paper production, and in particular to a decorative paper production process based on water-based ink gravure printing. Background Art

[0002] In my country, gravure printing is widely used in food, medicine and tobacco packaging industries, and is closely related to people's lives and health. Traditional gravure printing inks use a large amount of volatile organic solvents, which not only pollute the environment, but also the residual organic solvents in the printed products are harmful to human health. In the actual production process of decorative paper printed products, due to printing machinery, process flow, personnel operation and environmental control, some printing defects and quality problems often occur, resulting in an increase in the scrap rate and affecting the company's benefits. The printing quality evaluation process should not only detect these scraps so that the decorative paper products meet the delivery requirements, but also help companies optimize the process flow and improve product quality.

[0003] As human civilization develops faster and faster, sustainable development and green environmental protection become social trends. The development and application of water-based inks can greatly improve the printing operating environment and enhance product quality and safety, thus attracting the attention and favor of the packaging and printing industry. Due to the large latent heat of evaporation and low evaporation rate of water-based inks, water-based inks have problems such as high energy consumption for drying, long drying time, and incomplete drying during application. At the same time, the adhesion of water-based inks in the prior art is not high, and it is easy to fall off after a long time of printing. Therefore, the study of the drying characteristics and adhesion properties of water-based gravure water-based inks has important practical significance for further promoting the application of water-based inks.

[0004] The use of water-based ink as raw material in gravure printing of decorative paper has the advantages of environmental protection, low VOC (volatile organic compound) emissions, and fast drying. Compared with traditional solvent-based inks, water-based inks are more in line with modern environmental protection requirements, reduce pollution to the environment, and are more friendly to the health of printing workers and end users.

[0005] Chinese invention patent: Application No. 202310278334.4 discloses a production process for highly wear-resistant and scratch-resistant wood grain decorative paper, comprising the following steps: S1, selecting paper; S2, printing; S3, first gluing; S4, drying; S5, first hot pressing; S6, second gluing; S7, second hot pressing. The invention has the beneficial effects of improving the convenience of wood grain decorative paper during use, hardening and resisting wear on both sides of the surface of the wood grain decorative paper through the film, making the surface of the wood grain original color kraft paper more resistant to friction and scratches, while avoiding the occurrence of moisture and mildew on the wood grain decorative paper during use, thereby improving the durability of the wood grain decorative paper. However, the adhesion and aging resistance of the decorative paper obtained in the invention are not good. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a decorative paper production process based on water-based ink gravure printing.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The production process of decorative paper based on water-based ink gravure printing includes the following steps:

[0009] S1 pretreatment: the base paper is subjected to a water-passing process by roller coating to obtain a wet base paper;

[0010] S2 drying: drying the wet base paper with a mirror roller to obtain dry paper;

[0011] S3 gravure printing: adding the prepared water-based ink into the ink tank of the gravure printing machine, and installing the above-mentioned dried paper on the gravure printing machine to perform gravure printing to obtain gravure printing paper;

[0012] S4 Drying: Drying the gravure printing paper and rolling it up to obtain decorative paper based on gravure printing with water-based ink.

[0013] The moisture content of the wet base paper in S1 is 35-45%.

[0014] The mirror roller drying temperature in S2 is 100-105° C., and the mirror roller drying time is 0.5-2 min.

[0015] The gravure printing mesh in S3 is 80-120 mesh, the printing pressure is 800-880N, the printing speed is 100-140m / min, and the amount of water-based ink is 2.5-4g / m 2 .

[0016] The water-based ink in S3 is prepared from the following raw materials in parts by weight: 15-30 parts by weight of water-based acrylic resin emulsion, 15-25 parts by weight of modified polyurethane emulsion, 0.5-2 parts by weight of silica, 5-10 parts by weight of pigment, 0.5-1 parts by weight of surfactant, 0.3-0.8 parts by weight of defoamer, 0.5-1.5 parts by weight of leveling agent, and 25-50 parts by weight of water are mixed, and stirred at 400-800 rpm for 20-50 minutes to obtain the ink.

[0017] The pigment is at least one of carbon black, permanent yellow GG, direct red 83, titanium chrome green and phthalocyanine blue.

[0018] The surfactant is at least one of sodium dodecyl sulfonate, ammonium polymethacrylate, glycerol polyoxyethylene ether, and OP emulsifier; the defoamer is at least one of tributyl phosphate, polyether-modified polysiloxane, and silicone emulsion; the leveling agent is at least one of polydimethylsiloxane, silicone polyether-modified resin, and polyether-modified polysiloxane BYK333.

[0019] Printing inks must first have good adhesion and aging resistance. Because decorative paper undergoes an impregnation process during the manufacturing process, the pigment in the ink must be firmly attached to the surface of the paper to prevent fading and dispersion in subsequent processes. If the ink's adhesion is too low, the pigment will enter the glue tank during the impregnation process and will also stick to the pad during hot pressing. Printing inks must have excellent aging resistance. Decorative paper is often exposed to the air and is greatly affected by the environment. Therefore, the ink used to print decorative paper is required to have good aging resistance to temperature, humidity, light, and ultraviolet rays.

[0020] Graphene oxide is easy to agglomerate in the water-based ink system, resulting in uneven dispersion, which affects the performance of the ink. Therefore, when using graphene oxide, it needs to be modified to improve its dispersion performance in the ink. Branched hydroxy silane has a very rich active group. Branched hydroxy silane can increase the reaction binding sites with graphene, improve the modification efficiency, and can also be effectively dispersed with other raw materials in the ink through the similar compatibility principle. Therefore, the present invention first improves the dispersibility of graphene in the polyurethane matrix through modification with branched hydroxy silane, ensures that the performance of the ink is uniform and consistent during the printing process, and obtains a higher quality printing effect.

[0021] Specifically, in M1, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is first stirred in trichloromethane, ammonium chloride, chloroethanol, sodium carbonate, and ethanol to synthesize branched hydroxysilane; M2 mixes graphene oxide and branched hydroxysilane, adds ethanol aqueous solution and heats to react, and obtains silane-modified graphene through condensation reaction; M3 mixes hexamethylene diisocyanate, polycarbonate diol and N,N-dimethylformamide and heats to react to obtain a polyurethane prepolymer; 1,4-butanediol, (E)-oct-4-ene-1,8-dioic acid, dibutyltin dilaurate and the above-mentioned silane-modified graphene are added, and through heating reaction, the silane-modified graphene and the polyurethane prepolymer are chemically bonded to obtain a modified polyurethane emulsion.

[0022] The preparation method of the modified polyurethane emulsion is as follows:

[0023] M1. Mix graphene oxide and water and perform ultrasonic treatment to obtain graphene oxide slurry; mix silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate and ethanol and stir to obtain branched hydroxy silane;

[0024] M2, mixing the graphene oxide and the branched hydroxysilane, adding ethanol aqueous solution and heating to react, to obtain silane-modified graphene;

[0025] M3. Hexamethylene diisocyanate, polycarbonate diol and N,N-dimethylformamide are mixed and heated to react to obtain a polyurethane prepolymer; 1,4-butanediol, (E)-oct-4-ene-1,8-dioic acid, dibutyltin dilaurate and the above-mentioned silane-modified graphene are added, heated to react, and a modified polyurethane emulsion is obtained.

[0026] Using branched hydroxysilane-modified graphene in modified polyurethane as the main raw material in water-based ink can improve the adhesion to ink and the dispersion performance of modified ink in gravure printing, while enhancing the heat resistance and aging resistance of decorative paper. Specifically: branched hydroxysilane can react chemically with the polyurethane matrix, thereby significantly improving the adhesion between the ink and the substrate, which can prevent the printed pattern from peeling or fading during use and extend the service life of the decorative paper; the introduction of branched hydroxysilane can improve the dispersion of graphene in polyurethane and avoid graphene agglomeration in the matrix, thereby ensuring the uniformity of the ink performance, which helps to improve the printing quality and obtain a more uniform and delicate pattern effect; the introduction of graphene can improve the heat resistance and aging resistance of polyurethane, delay the aging process of the material, and the printed pattern can still remain bright and clear under high temperature or exposure to sunlight. Therefore, using branched hydroxysilane-modified graphene in modified polyurethane water-based ink can significantly improve the performance of gravure decorative paper, including adhesion, dispersibility, chemical resistance and aging resistance, so that it can perform well in various application scenarios and meet higher quality and durability requirements.

[0027] Preferably, the preparation method of the modified polyurethane emulsion is as follows:

[0028] M1. Mix 8-15 parts by weight of graphene oxide and 80-150 parts by weight of water, and perform ultrasonic treatment for 20-50 min at an ultrasonic power of 200-400 W and an ultrasonic frequency of 50-80 kHz to obtain a graphene oxide slurry; uniformly mix silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate, and ethanol in a mass ratio of (2-6): (10-20): (2-5): (1-3): (0.5-1): (5-15), stir at 40-60° C. and 200-600 rpm for 6-20 h, and perform vacuum distillation to obtain a branched hydroxysilane;

[0029] M2, 40-80 parts by weight of the above-mentioned graphene oxide and 2-5 parts by weight of the above-mentioned branched hydroxysilane are mixed, 30-80 parts by weight of 20-40wt% ethanol aqueous solution are added, ultrasonic power is 200-400W, ultrasonic frequency is 50-80kHz, ultrasonic is carried out for 20-50min, at 80-100°C, 600-900rpm, react for 2-5h, filter, wash and dry to obtain silane-modified graphene;

[0030] M3. Mix 5-10 parts by weight of hexamethylene diisocyanate, 4-9 parts by weight of polycarbonate diol and 40-100 parts by weight of N,N-dimethylformamide, react at 75-90°C and 200-600rpm for 0.5-2h to obtain a polyurethane prepolymer; add 0.3-1 parts by weight of 1,4-butanediol, 0.1-0.5 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.02-0.1 parts by weight of dibutyltin dilaurate and 2-5 parts by weight of the above-mentioned silane-modified graphene, react at 90-115°C and 200-600rpm for 1-4h, remove the solvent by reduced pressure distillation, and obtain a modified polyurethane emulsion.

[0031] The present invention simultaneously adopts 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane to modify graphene, which has a synergistic effect in enhancing the dispersibility of graphene and the adhesion of ink: hydroxyl silane and carboxyl silane coupling agents can react with the surface of graphene through their different functional groups respectively, so that the surface of graphene has multiple active groups at the same time, further enhancing the dispersibility of graphene in the aqueous system, and such multi-functional group modification can reduce the agglomeration phenomenon of graphene in the ink, ensure the uniformity and stability of the ink, and thus improve the printing quality; silane containing hydroxyl and carboxyl groups can form strong hydrogen bonds or covalent bonds with carboxyl groups and other polar groups in a polyurethane matrix, thereby significantly enhancing the adhesion of the ink to the substrate, and the strong adhesion can ensure the firmness of the printed pattern on the decorative paper, reduce the shedding and peeling phenomena, and extend the service life of the decorative paper.

[0032] The silane is a mixture of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane in a mass ratio of (1.2-2):1; preferably, the silane is a mixture of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane in a mass ratio of 3:2.

[0033] The decorative paper based on gravure printing of water-based ink is prepared by adopting the production process described above.

[0034] Beneficial effects of the present invention: The present invention provides a decorative paper production process based on water-based ink gravure printing, and uses branched hydroxysilane-modified graphene to modify polyurethane as the main raw material in the water-based ink, which can improve the adhesion to the ink and the dispersion performance of the modified ink in gravure printing, while enhancing the heat resistance and aging resistance of the decorative paper to obtain a higher quality printing effect. DETAILED DESCRIPTION

[0035] The above content of the present invention is further described in detail below in conjunction with specific implementation modes, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments.

[0036] Introduction of some raw materials in this application:

[0037] Base paper, commercially available special base paper brown paper, purchased from Hangzhou Haixin Paper Co., Ltd., item number: 2023005, weight: 60-70g / m 2 .

[0038] Water-based acrylic resin emulsion was purchased from Beijing Dongfang Chennuo Chemical Technology Co., Ltd., model: PE-100.

[0039] Graphene oxide was purchased from Shenzhen Turing New Materials Co., Ltd., with a sheet size of 0.5-5um, a sheet size of 0.5-5um, and a specific surface area of ​​1000-1217m 2 / g, item number: 0002.

[0040] Polydimethylsiloxane was purchased from Shandong Huachen New Materials Co., Ltd., item number: HC05.

[0041] Polycarbonate diol was purchased from Hubei Darli Chemical Co., Ltd., model: Darl-1.

[0042] Embodiment 1 A process for producing decorative paper based on water-based ink gravure printing comprises the following steps:

[0043] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0044] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0045] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m2 , obtaining gravure printing paper;

[0046] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0047] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of modified polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0048] The preparation method of the modified polyurethane emulsion is as follows:

[0049] M1, take 10 parts by weight of graphene oxide and 90 parts by weight of water, mix them, and ultrasonicate them at an ultrasonic power of 300W and an ultrasonic frequency of 70kHz for 30 minutes to obtain a graphene oxide slurry; silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate, and ethanol are uniformly mixed in a mass ratio of 4:15:2.5:2:0.8:10, stirred at 50°C and 400rpm for 12h, and distilled under reduced pressure to obtain a branched hydroxysilane; the silane is a mixture of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane in a mass ratio of 3:2;

[0050] M2, 50 parts by weight of the above-mentioned graphene oxide and 3 parts by weight of the above-mentioned branched hydroxysilane were mixed, 50 parts by weight of a 30 wt% ethanol aqueous solution were added, ultrasonicated for 30 min at an ultrasonic power of 300 W and an ultrasonic frequency of 70 kHz, reacted at 90° C. and 800 rpm for 3 h, filtered, washed, and dried to obtain silane-modified graphene;

[0051] M3. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.05 parts by weight of dibutyltin dilaurate and 3 parts by weight of the above-mentioned silane-modified graphene, react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0052] Embodiment 2 A process for producing decorative paper based on water-based ink gravure printing comprises the following steps:

[0053] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0054] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0055] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m 2 , obtaining gravure printing paper;

[0056] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0057] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of modified polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0058] The preparation method of the modified polyurethane emulsion is as follows:

[0059] M1, take 10 parts by weight of graphene oxide and 90 parts by weight of water, mix them, and ultrasonicate them at an ultrasonic power of 300W and an ultrasonic frequency of 70kHz for 30 minutes to obtain a graphene oxide slurry; silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate, and ethanol are uniformly mixed in a mass ratio of 4:15:2.5:2:0.8:10, stirred at 50°C and 400rpm for 12h, and distilled under reduced pressure to obtain a branched hydroxysilane; the silane is 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane;

[0060] M2, 50 parts by weight of the above-mentioned graphene oxide and 3 parts by weight of the above-mentioned branched hydroxysilane were mixed, 50 parts by weight of a 30 wt% ethanol aqueous solution were added, ultrasonicated for 30 min at an ultrasonic power of 300 W and an ultrasonic frequency of 70 kHz, reacted at 90° C. and 800 rpm for 3 h, filtered, washed, and dried to obtain silane-modified graphene;

[0061] M3. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.05 parts by weight of dibutyltin dilaurate and 3 parts by weight of the above-mentioned silane-modified graphene, react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0062] Embodiment 3 A process for producing decorative paper based on water-based ink gravure printing comprises the following steps:

[0063] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0064] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0065] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m 2 , obtaining gravure printing paper;

[0066] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0067] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of modified polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0068] The preparation method of the modified polyurethane emulsion is as follows:

[0069] M1, take 10 parts by weight of graphene oxide and 90 parts by weight of water, mix them, and ultrasonicate them at an ultrasonic power of 300W and an ultrasonic frequency of 70kHz for 30 minutes to obtain graphene oxide slurry; silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate, and ethanol are uniformly mixed in a mass ratio of 4:15:2.5:2:0.8:10, stirred at 50°C and 400rpm for 12h, and distilled under reduced pressure to obtain branched hydroxy silane; the silane is 1.3-bis(3-carboxypropyl)tetramethyldisiloxane;

[0070] M2, 50 parts by weight of the above-mentioned graphene oxide and 3 parts by weight of the above-mentioned branched hydroxysilane were mixed, 50 parts by weight of a 30 wt% ethanol aqueous solution were added, ultrasonicated for 30 min at an ultrasonic power of 300 W and an ultrasonic frequency of 70 kHz, reacted at 90° C. and 800 rpm for 3 h, filtered, washed, and dried to obtain silane-modified graphene;

[0071] M3. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.05 parts by weight of dibutyltin dilaurate and 3 parts by weight of the above-mentioned silane-modified graphene, react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0072] Comparative Example 1 A production process for decorative paper based on water-based ink gravure printing comprises the following steps:

[0073] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0074] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0075] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m 2 , obtaining gravure printing paper;

[0076] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0077] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0078] The preparation method of the polyurethane emulsion is as follows:

[0079] M1. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, and 0.05 parts by weight of dibutyltin dilaurate, and react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0080] Comparative Example 2 A decorative paper production process based on water-based ink gravure printing comprises the following steps:

[0081] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0082] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0083] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m 2 , obtaining gravure printing paper;

[0084] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0085] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of modified polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0086] The preparation method of the modified polyurethane emulsion is as follows:

[0087] M1, take 10 parts by weight of graphene oxide and 90 parts by weight of water and mix them, and ultrasonicate them at an ultrasonic power of 300 W and an ultrasonic frequency of 70 kHz for 30 min to obtain a graphene oxide slurry;

[0088] M2, 50 parts by weight of the above-mentioned graphene oxide and 3 parts by weight of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane were mixed, 50 parts by weight of 30 wt% ethanol aqueous solution were added, ultrasonicated at an ultrasonic power of 300 W and an ultrasonic frequency of 70 kHz for 30 min, reacted at 90 ° C and 800 rpm for 3 h, filtered, washed and dried to obtain silane-modified graphene;

[0089] M3. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.05 parts by weight of dibutyltin dilaurate and 3 parts by weight of the above-mentioned silane-modified graphene, react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0090] Comparative Example 3 A decorative paper production process based on water-based ink gravure printing comprises the following steps:

[0091] S1 pretreatment: the base paper is subjected to a conventional water-passing process by roller coating to moisten the dry base paper to obtain a wet base paper, wherein the moisture content of the wet base paper is 40%;

[0092] S2 Drying: The wet base paper is placed at 110°C for mirror roller drying for 1 minute, and the top surface of the wet base paper is bonded to the mirror surface of the mirror roller to obtain a dried paper;

[0093] S3 gravure printing: add the prepared water-based ink into the ink tank of the gravure printing machine, and install the above-mentioned dry paper on the gravure printing machine for gravure printing. The gravure screen is 100 mesh, the printing pressure is 850N, the printing speed is 120m / min, and the amount of water-based ink is 3g / m 2 , obtaining gravure printing paper;

[0094] S4 Drying: Dry the gravure printing paper at 80° C. for 2 minutes, roll up the dried gravure printing paper, and obtain decorative paper based on gravure printing of water-based ink.

[0095] The water-based ink is prepared from the following raw materials in parts by weight: 20 parts by weight of water-based acrylic resin emulsion, 18 parts by weight of modified polyurethane emulsion, 1 part by weight of silicon dioxide, 8 parts by weight of carbon black, 0.8 parts by weight of sodium dodecyl sulfate, 0.5 parts by weight of tributyl phosphate, 1 part by weight of polydimethylsiloxane, and 30 parts by weight of water are mixed and stirred at 600 rpm for 30 minutes.

[0096] The preparation method of the modified polyurethane emulsion is as follows:

[0097] M1. Silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate and ethanol were mixed uniformly in a mass ratio of 4:15:2.5:2:0.8:10, stirred at 50°C and 400rpm for 12h, and distilled under reduced pressure to obtain branched hydroxy silane; the silane was a mixture of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane in a mass ratio of 3:2;

[0098] M2, mixing 5 parts by weight of graphene oxide and 3 parts by weight of the above-mentioned branched hydroxysilane to obtain a mixture of graphene oxide and branched hydroxysilane;

[0099] M3. Mix 8 parts by weight of hexamethylene diisocyanate, 7 parts by weight of polycarbonate diol and 50 parts by weight of N,N-dimethylformamide, and react at 80°C and 400rpm for 1h to obtain a polyurethane prepolymer; add 0.5 parts by weight of 1,4-butanediol, 0.2 parts by weight of (E)-oct-4-ene-1,8-dioic acid, 0.05 parts by weight of dibutyltin dilaurate and 3 parts by weight of the above-mentioned mixture of graphene oxide and branched hydroxysilane, react at 105°C and 400rpm for 2h, and remove the solvent by reduced pressure distillation to obtain a modified polyurethane emulsion.

[0100] Test Example 1 Adhesion and peeling force test of decorative paper: The test was carried out with reference to the adhesion test standard in the national standard GB / T13217.7-2023 "Ink Adhesion Test Method". Three different positions were tested in each group of samples, and the average value was taken. The results are shown in Table 1.

[0101] The peeling force test was carried out with reference to the national standard GB / T 26394-2011 "Water-based Thin Film Gravure Composite Ink". Three different positions were taken for testing in each group of samples, and the average value was taken. The results are shown in Table 1.

[0102] Table 1 Adhesion and peeling test results of decorative paper printed with water-based ink

[0103] Adhesion, % Peel force, N / 15mm Example 1 100% 2.8 Example 2 99% 2.6 Example 3 98% 2.5 Comparative Example 1 75% 0.8 Comparative Example 2 89% 2.0 Comparative Example 3 80% 1.2

[0104] Test Example 2 Aging resistance test: The aging resistance of the decorative paper was tested with reference to the national standard GB / T 7911-2013 "Thermosetting resin impregnated paper high pressure decorative laminate (HPL)" to see if there was any cracking. The results are shown in Table 2.

[0105] Whether it is cracked Example 1 no Comparative Example 1 yes Comparative Example 2 yes Comparative Example 3 yes

[0106] It can be seen from the above results that the decorative paper based on water-based ink gravure printing prepared in the present invention has good adhesion and aging resistance. Comparing Examples 1-3, it can be seen that the present invention simultaneously uses 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane to modify graphene, which has a synergistic effect in enhancing the dispersibility of graphene and the adhesion of ink: hydroxyl silane and carboxyl silane coupling agents can react with the graphene surface through their different functional groups, respectively, so that the graphene surface has multiple active groups at the same time, further enhancing the dispersibility of graphene in the aqueous system. This multi-functional group modification can reduce the agglomeration of graphene in the ink, ensure the uniformity and stability of the ink, and thus improve the printing quality; silane containing hydroxyl and carboxyl groups can form strong hydrogen bonds or covalent bonds with carboxyl and other polar groups in the polyurethane matrix, thereby significantly enhancing the adhesion of the ink to the substrate. The strong adhesion can ensure the firmness of the printed pattern on the decorative paper, reduce shedding and peeling, and extend the service life of the decorative paper.

[0107] Further comparison of Example 1 and Comparative Examples 1-3 shows that Example 1 uses branched hydroxysilane-modified graphene for modified polyurethane as the main raw material in water-based ink, which can improve the adhesion to ink and the dispersion performance of modified ink in gravure printing, and enhance the heat resistance and aging resistance of decorative paper. Specifically: branched hydroxysilane can react chemically with the polyurethane matrix, thereby significantly improving the adhesion between the ink and the substrate, which can prevent the printed pattern from peeling or discoloring during use and extend the service life of the decorative paper; the introduction of branched hydroxysilane can improve the dispersibility of graphene in polyurethane and avoid graphene agglomeration in the matrix, thereby ensuring that the performance of the ink is uniform, which helps to improve the printing quality and obtain a more uniform and delicate pattern effect; the introduction of graphene can improve the heat resistance and aging resistance of polyurethane, delay the aging process of the material, and the printed pattern can still remain bright and clear at high temperatures or exposed to sunlight. Therefore, using branched hydroxysilane-modified graphene in modified polyurethane water-based ink can significantly improve the performance of gravure decorative paper, including adhesion, dispersibility, chemical resistance and aging resistance, so that it can perform well in various application scenarios and meet higher quality and durability requirements.

Claims

1. A process for producing decorative paper based on water-based ink gravure printing, characterized in that: The steps include: S1 pretreatment: the base paper is subjected to a water-passing process by roller coating to obtain a wet base paper; S2 drying: drying the wet base paper with a mirror roller to obtain dry paper; S3 gravure printing: adding the prepared water-based ink into the ink tank of the gravure printing machine, and installing the above-mentioned dried paper on the gravure printing machine to perform gravure printing to obtain gravure printing paper; S4 drying: drying the gravure printing paper and rolling it to obtain decorative paper based on gravure printing of water-based ink; The water-based ink in S3 is prepared from the following raw materials in parts by weight: 15-30 parts by weight of water-based acrylic resin emulsion, 15-25 parts by weight of modified polyurethane emulsion, 0.5-2 parts by weight of silicon dioxide, 5-10 parts by weight of pigment, 0.5-1 parts by weight of surfactant, 0.3-0.8 parts by weight of defoamer, 0.5-1.5 parts by weight of leveling agent, and 25-50 parts by weight of water are mixed and stirred to obtain the ink; The preparation method of the modified polyurethane emulsion is as follows: M1. Mix graphene oxide and water and perform ultrasonic treatment to obtain graphene oxide slurry; mix silane, chloroform, ammonium chloride, chloroethanol, sodium carbonate and ethanol and stir to obtain branched hydroxy silane; M2, mixing the graphene oxide and the branched hydroxysilane, adding ethanol aqueous solution and heating to react, to obtain silane-modified graphene; M3. Hexamethylene diisocyanate, polycarbonate diol and N,N-dimethylformamide are mixed and heated to react to obtain a polyurethane prepolymer; 1,4-butanediol, (E)-oct-4-ene-1,8-dioic acid, dibutyltin dilaurate and the above-mentioned silane-modified graphene are added, heated to react, and a modified polyurethane emulsion is obtained.

2. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The moisture content of the wet base paper in S1 is 35-45%.

3. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The mirror roller drying temperature in S2 is 100-105° C., and the mirror roller drying time is 0.5-2 min.

4. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The mesh size of the gravure printing in S3 is 80-120 meshes, the printing pressure is 800-880N, the printing speed is 100-140m / min, and the amount of the water-based ink is 1.5-2g / m 2 .

5. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The pigment is at least one of carbon black, permanent yellow GG, direct red 83, titanium chrome green and phthalocyanine blue.

6. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The surfactant is at least one of sodium dodecyl sulfonate, ammonium polymethacrylate, glycerol polyoxyethylene ether, and OP emulsifier; the defoamer is at least one of tributyl phosphate, polyether-modified polysiloxane, and silicone emulsion; the leveling agent is at least one of polydimethylsiloxane, silicone polyether-modified resin, and polyether-modified polysiloxane BYK333.

7. The decorative paper production process based on water-based ink gravure printing according to claim 1, characterized in that: The silane is at least one of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane and 1.3-bis(3-carboxypropyl)tetramethyldisiloxane.

8. Decorative paper based on water-based ink gravure printing, prepared by the production process according to any one of claims 1 to 7.