An anti-counterfeiting watermark paper and its manufacturing method

Abstract

The present invention discloses an anti-counterfeiting watermark paper and a manufacturing method thereof, comprising the following steps: After processing the anti-counterfeiting film, it is added into the pulp through a directional release device, and is directionally distributed in a certain corner of the paper or evenly distributed in the paper. The application amount of the anti-counterfeiting film is 0.3-1% of the paper area; By directly applying the anti-counterfeiting film directionally in the paper, no new pulping, papermaking and other steps are added, reducing the pressure on the environment caused by traditional processes. Moreover, the anti-counterfeiting film endows excellent anti-counterfeiting performance by enhancing the excellent fluorescence quantum efficiency of molybdenum disulfide quantum dots and improving the fluorescence intensity. And by using cellulose nanofibers as a carrier, molybdenum disulfide quantum dots can be loaded more evenly, preventing the phenomenon of uneven fluorescence from occurring.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-counterfeiting paper, and particularly relates to an anti-counterfeiting watermark paper and a manufacturing method thereof. Background Art

[0002] Watermark paper is one of the commonly used anti-counterfeiting papers at present. Watermark paper includes two-level watermarks with obvious bright and dark effects and multi-level watermarks with a soft transition between bright and dark. Among multi-level watermarks, the most typical one is represented by a three-dimensional convex structure.

[0003] The preparation methods of watermark paper include traditional watermarks and color watermarks. Traditional watermarks mainly use a pre-made watermark roller with a watermark pattern to perform fiber stacking or wet paper embossing on the paper surface to obtain the required black watermark or white watermark. However, since the color of the watermark is the same as that of the paper in traditional watermarks, it does not have a visual color discrimination function. Color watermarks are mainly prepared by introducing an intermediate color layer during the production process of traditional watermarks, combining traditional watermark methods, or by spray-printing and transfer-printing methods. However, the watermark paper prepared by this method usually adds new pulping, papermaking and other steps, increasing the pressure of environmental pollution brought about in the pulp papermaking process. Therefore, it is an urgent technical problem to provide an anti-counterfeiting watermark paper with good anti-counterfeiting effect and low environmental pollution during the preparation process. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an anti-counterfeiting watermark paper and a manufacturing method thereof.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] An anti-counterfeiting watermark paper, comprising base paper and an anti-counterfeiting film, wherein the anti-counterfeiting film is prepared by the following steps:

[0007] Step S1: After bleaching jute fibers, disperse them in deionized water, add sodium bromide and an oxidizing agent, stir evenly, then add a 15% sodium hypochlorite solution by mass fraction, stir evenly and react at a constant speed. During the reaction process, add a 10% sodium hydroxide solution by mass fraction to maintain pH = 10.5 until the pH value does not decrease, and add anhydrous ethanol to terminate the reaction to obtain a slurry. Centrifuge and wash with deionized water until the washing liquid is neutral, and homogenize to obtain a cellulose nanofiber hydrogel;

[0008] In step S1, a cellulose nanofiber hydrogel is prepared by oxidizing with an oxidizing agent and combining with a high-pressure homogenization method;

[0009] Step S2, adding sodium molybdate to deionized water, stirring at a uniform speed until dissolved, adding a 10% mass fraction sodium hydroxide aqueous solution to adjust the pH until the pH = 6, and then adding a 1% mass fraction L-cysteine ​​aqueous solution to the reactor, heating to 200 ° C, keeping the reaction for 12 hours, cooling to room temperature after the reaction is completed, taking out, centrifuging at 10000r / min for 15min, collecting the supernatant, dialyzing through a dialysis bag with a molecular weight cutoff of 3600 for 6 hours, and then vacuum drying at 55 ° C for 6 hours to obtain molybdenum disulfide quantum dots;

[0010] In step S2, sodium molybdate is used as a molybdenum source and L-cysteine ​​is used as a sulfur source to synthesize molybdenum disulfide quantum dots by a hydrothermal method;

[0011] Step S3, adding the prepared molybdenum disulfide quantum dots into deionized water, stirring at a constant speed for 30 minutes, then dropping a tryptophan solution with a concentration of 0.5 mmol / L, magnetically stirring for 30 minutes, sealing and heating to 80° C., continuing stirring and reacting for 12 hours, to obtain enhanced molybdenum disulfide quantum dots;

[0012] In step S3, tryptophan is used to improve the fluorescence quantum efficiency of molybdenum disulfide quantum dots. Tryptophan contains amino and carboxyl groups. Molybdenum disulfide quantum dots are similar to tryptophan and have similar six-membered ring structures. They can be compounded by π-π stacking. On the one hand, the fluorescence quantum efficiency of molybdenum disulfide quantum dots is improved, and on the other hand, they can enter the molybdenum disulfide quantum dot layer to prevent the agglomeration of molybdenum disulfide quantum dots.

[0013] Step S4, add cellulose nanofiber hydrogel to deionized water, stir at a uniform speed for 30 minutes, then add reinforcing molybdenum disulfide quantum dots, continue stirring for 30 minutes, add 30% gelatin aqueous solution, stir evenly to form a mixed solution, evenly coat it on the template surface, and dry it to form an anti-counterfeiting film.

[0014] Furthermore: in step S4, a texture pattern is engraved on the surface of the template, and the texture depth is 0.01-0.03 mm.

[0015] Further: in step S1, the dosage ratio of jute fiber, sodium bromide, oxidant, sodium hypochlorite solution and anhydrous ethanol is controlled to be 5-8 g: 0.5-0.6 g: 0.1-0.15 g: 40.5-42.8 g: 2-3 mL.

[0016] Furthermore, in step S2, the dosage ratio of sodium molybdate to deionized water is controlled to be 0.12-0.15 g:12-15 mL, and the weight ratio of sodium molybdate to L-cysteine ​​is controlled to be 1:2.

[0017] Further: in step S3, the dosage ratio of molybdenum disulfide quantum dots, deionized water and tryptophan solution is controlled to be 0.05-0.08 g: 0.5 mL: 3 mL.

[0018] Further: In step S4, the weight ratio of the cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots and gelatin is controlled to be 2-3∶100∶0.2-0.5∶10-15.

[0019] A method for manufacturing an anti-counterfeiting watermark paper, comprising the following steps:

[0020] After processing the anti-counterfeiting film, it is added to the pulp through a directional release device and is directionally distributed in a certain corner of the paper or evenly distributed in the paper. The application amount of the anti-counterfeiting film is 0.3-1% of the paper area.

[0021] Advantages of the present invention:

[0022] The present invention prepares an anti-counterfeiting watermark paper, which endows the paper with excellent anti-counterfeiting performance by preparing an anti-counterfeiting film. Moreover, it is directly directionally applied to the paper through the anti-counterfeiting film, without adding new pulping, papermaking and other steps, reducing the pressure on the environment caused by traditional processes. And the anti-counterfeiting film improves the fluorescence intensity by enhancing the excellent fluorescence quantum efficiency of molybdenum disulfide quantum dots, endowing the anti-counterfeiting film with excellent anti-counterfeiting performance. Moreover, by using cellulose nanofibers as a carrier, molybdenum disulfide quantum dots can be more evenly loaded, preventing the phenomenon of uneven fluorescence. Specific embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Example 1

[0024] An anti-counterfeiting watermark paper, comprising a base paper and an anti-counterfeiting film, wherein the anti-counterfeiting film is prepared through the following steps:

[0025] Step S1: After bleaching jute fibers, disperse them in deionized water, add sodium bromide and TEMPO oxidant, stir evenly, then add a 15% sodium hypochlorite solution by mass fraction, stir evenly and react. During the reaction, a 10% sodium hydroxide solution by mass fraction is added dropwise to maintain pH = 10.5 until the pH value does not decrease, and anhydrous ethanol is added dropwise to terminate the reaction, obtaining a slurry. The slurry is centrifugally washed with deionized water until the washing liquid is neutral, and homogenized to obtain a cellulose nanofiber hydrogel. The dosage ratio of jute fibers, sodium bromide, TEMPO oxidant, sodium hypochlorite solution and anhydrous ethanol is controlled to be 5g∶0.5g∶0.1g∶40.5g∶2mL;

[0026] Step S2: Add sodium molybdate into deionized water, stir evenly until it dissolves, add 10% sodium hydroxide aqueous solution by mass fraction dropwise to adjust the pH until pH = 6, then add it and 1% L-cysteine aqueous solution into the reaction kettle, heat up to 200 °C, keep the temperature for reaction for 12 h, after the reaction ends, cool it to room temperature, take it out, centrifuge at 10000 r / min for 15 min, collect the supernatant, dialyze it through a dialysis bag with a molecular weight cut-off of 3600 for 6 h, and then vacuum dry it at 55 °C for 6 h to obtain molybdenum disulfide quantum dots. Control the dosage ratio of sodium molybdate to deionized water as 0.12 g∶12 mL, and the weight ratio of sodium molybdate to L-cysteine as 1∶2;

[0027] Step S3: Add the obtained molybdenum disulfide quantum dots into deionized water, stir evenly for 30 min, then add 0.5 mmol / L tryptophan solution dropwise, stir magnetically for 30 min, then seal and heat up to 80 °C, continue to stir and react for 12 h to obtain enhanced molybdenum disulfide quantum dots. Control the dosage ratio of molybdenum disulfide quantum dots, deionized water and tryptophan solution as 0.05 g∶0.5 mL∶3 mL;

[0028] Step S4: Add cellulose nanofiber hydrogel into deionized water, stir evenly for 30 min, then add enhanced molybdenum disulfide quantum dots, continue to stir for 30 min, add 30% gelatin aqueous solution by mass fraction, stir evenly to form a mixed solution, evenly coat it on the surface of the template, and make a security film after drying. Control the weight ratio of cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots and gelatin as 2∶100∶0.2∶10.

[0029] The surface of the template described in Step S4 is engraved with a texture pattern, and the texture depth is 0.01 mm. Example 2

[0030] A security watermark paper, comprising base paper and a security film, and the security film is made by the following steps:

[0031] Step S1: Disperse bleached jute fibers in deionized water, add sodium bromide and TEMPO oxidant, stir evenly, then add 15% sodium hypochlorite solution by mass fraction, stir evenly and react. During the reaction process, add 10% sodium hydroxide solution by mass fraction dropwise to maintain pH = 10.5 until the pH value does not decrease, add anhydrous ethanol dropwise to terminate the reaction, obtain a slurry, wash it with deionized water by centrifugation until the washing liquid is neutral, and homogenize it to obtain cellulose nanofiber hydrogel. Control the dosage ratio of jute fibers, sodium bromide, TEMPO oxidant, sodium hypochlorite solution and anhydrous ethanol as 6 g∶0.55 g∶0.12 g∶41.5 g∶2 mL;

[0032] Step S2: Add sodium molybdate into deionized water, stir evenly until dissolved, add 10% sodium hydroxide aqueous solution by mass fraction to adjust the pH until pH = 6, then add 1% L-cysteine aqueous solution by mass fraction into the reaction kettle, heat up to 200 °C, keep the temperature for reaction for 12 h, cool to room temperature after the reaction, take out, centrifuge at 10000 r / min for 15 min, collect the supernatant, dialyze through a dialysis bag with a molecular weight cut-off of 3600 for 6 h, and then vacuum dry at 55 °C for 6 h to obtain molybdenum disulfide quantum dots. Control the dosage ratio of sodium molybdate to deionized water as 0.14 g∶14 mL, and the weight ratio of sodium molybdate to L-cysteine as 1∶2;

[0033] Step S3: Add the obtained molybdenum disulfide quantum dots into deionized water, stir evenly for 30 min, then add tryptophan solution with a concentration of 0.5 mmol / L, stir magnetically for 30 min, seal and heat up to 80 °C, continue to stir and react for 12 h to obtain enhanced molybdenum disulfide quantum dots. Control the dosage ratio of molybdenum disulfide quantum dots, deionized water and tryptophan solution as 0.06 g∶0.5 mL∶3 mL;

[0034] Step S4: Add cellulose nanofiber hydrogel into deionized water, stir evenly for 30 min, then add enhanced molybdenum disulfide quantum dots, continue to stir for 30 min, add 30% gelatin aqueous solution by mass fraction, stir evenly to form a mixed solution, evenly coat it on the surface of the template, and make a security film after drying. Control the weight ratio of cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots and gelatin as 2.5∶100∶0.4∶14.

[0035] The surface of the template described in Step S4 is engraved with a texture pattern, and the texture depth is 0.02 mm. Example 3

[0036] A security watermark paper, comprising base paper and a security film, and the security film is made by the following steps:

[0037] Step S1: Bleach jute fibers and disperse them in deionized water, add sodium bromide and TEMPO oxidant, stir evenly, then add 15% sodium hypochlorite solution by mass fraction, stir evenly and react. During the reaction, add 10% sodium hydroxide solution by mass fraction to maintain pH = 10.5 until the pH value does not decrease, add absolute ethanol to terminate the reaction, obtain a slurry, centrifuge and wash with deionized water until the washing liquid is neutral, and homogenize to obtain cellulose nanofiber hydrogel. Control the dosage ratio of jute fibers, sodium bromide, TEMPO oxidant, sodium hypochlorite solution and absolute ethanol as 7 g∶0.58 g∶0.14 g∶42.5 g∶2.5 mL;

[0038] Step S2: Sodium molybdate is added to deionized water and stirred evenly until dissolved. An aqueous sodium hydroxide solution with a mass fraction of 10% is added dropwise to adjust the pH until pH = 6. Then, an aqueous L-cysteine solution with a mass fraction of 1% is added to the reaction kettle, the temperature is raised to 200 °C, and the reaction is kept for 12 h. After the reaction, it is cooled to room temperature, taken out, centrifuged at 10000 r / min for 15 min, the supernatant is collected, dialyzed through a dialysis bag with a molecular weight cut-off of 3600 for 6 h, and then vacuum dried at 55 °C for 6 h to obtain molybdenum disulfide quantum dots. The dosage ratio of sodium molybdate to deionized water is controlled to be 0.14 g∶14 mL, and the weight ratio of sodium molybdate to L-cysteine is 1∶2;

[0039] Step S3: The obtained molybdenum disulfide quantum dots are added to deionized water, stirred evenly for 30 min, then a tryptophan solution with a concentration of 0.5 mmol / L is added dropwise, magnetically stirred for 30 min, then sealed and heated to 80 °C, and continuously stirred and reacted for 12 h to obtain enhanced molybdenum disulfide quantum dots. The dosage ratio of molybdenum disulfide quantum dots, deionized water, and tryptophan solution is controlled to be 0.07 g∶0.5 mL∶3 mL;

[0040] Step S4: The cellulose nanofiber hydrogel is added to deionized water, stirred evenly for 30 min, then the enhanced molybdenum disulfide quantum dots are added, and stirring is continued for 30 min. An aqueous gelatin solution with a mass fraction of 30% is added and stirred evenly to form a mixed solution, which is evenly coated on the surface of the template and dried to make a security film. The weight ratio of cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots, and gelatin is controlled to be 2.8∶100∶0.4∶14.

[0041] The surface of the template is engraved with a texture pattern, and the texture depth is 0.03 mm. Example 4

[0042] A security watermark paper includes a base paper and a security film. The security film is made by the following steps:

[0043] Step S1: The jute fibers are bleached and dispersed in deionized water, sodium bromide and TEMPO oxidant are added, and stirred evenly. Then, an aqueous sodium hypochlorite solution with a mass fraction of 15% is added, and stirred evenly and reacted. During the reaction, an aqueous sodium hydroxide solution with a mass fraction of 10% is added dropwise to maintain pH = 10.5 until the pH value does not decrease. Anhydrous ethanol is added dropwise to terminate the reaction, and a slurry is obtained. It is centrifuged and washed with deionized water until the washing liquid is neutral, and homogenized to obtain a cellulose nanofiber hydrogel. The dosage ratio of jute fibers, sodium bromide, TEMPO oxidant, sodium hypochlorite solution, and anhydrous ethanol is controlled to be 8 g∶0.6 g∶0.15 g∶42.8 g∶3 mL;

[0044] Step S2: Add sodium molybdate into deionized water, stir evenly until it dissolves, add 10% sodium hydroxide aqueous solution by mass fraction dropwise to adjust the pH until pH = 6, then add it into the reaction kettle together with 1% L-cysteine aqueous solution by mass fraction, heat up to 200 °C, keep the temperature for reaction for 12 h, cool to room temperature after the reaction ends, take out, centrifuge at 10000 r / min for 15 min, collect the supernatant, dialyze through a dialysis bag with a molecular weight cut-off of 3600 for 6 h, and then dry in vacuum at 55 °C for 6 h to obtain molybdenum disulfide quantum dots. Control the dosage ratio of sodium molybdate to deionized water as 0.15 g∶15 mL, and the weight ratio of sodium molybdate to L-cysteine as 1∶2;

[0045] Step S3: Add the obtained molybdenum disulfide quantum dots into deionized water, stir evenly for 30 min, then add 0.5 mmol / L tryptophan solution dropwise, stir magnetically for 30 min, seal and heat up to 80 °C, continue stirring and reacting for 12 h to obtain enhanced molybdenum disulfide quantum dots. Control the dosage ratio of molybdenum disulfide quantum dots, deionized water and tryptophan solution as 0.08 g∶0.5 mL∶3 mL;

[0046] Step S4: Add cellulose nanofiber hydrogel into deionized water, stir evenly for 30 min, then add enhanced molybdenum disulfide quantum dots, continue stirring for 30 min, add 30% gelatin aqueous solution by mass fraction, stir evenly to form a mixed solution, evenly coat it on the surface of the template, and make a security film after drying. Control the weight ratio of cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots and gelatin as 3∶100∶0.5∶15.

[0047] In step S4, the surface of the template is engraved with a texture pattern, and the texture depth is 0.03 mm. Example 5

[0048] A method for making a security watermark paper, comprising the following steps:

[0049] Process the security film and add it into the pulp through a directional release device to distribute it evenly in the paper in a directional manner. The application amount of the security film is 0.3% of the paper area. Example 6

[0050] A method for making a security watermark paper, comprising the following steps:

[0051] Process the security film and add it into the pulp through a directional release device to distribute it evenly in the paper in a directional manner. The application amount of the security film is 0.8% of the paper area. Example 7

[0052] A method for making a security watermark paper, comprising the following steps:

[0053] After processing the anti-counterfeiting film, it is added to the pulp through a directional release device and evenly distributed in the paper in a directional manner. The application amount of the anti-counterfeiting film is 1% of the paper area.

[0054] Performance test:

[0055] Cut the anti-counterfeiting watermark paper to be tested into a size of 60mm×60mm. Use the reel device on the IGT crease resistance tester to roll the square specimen into a cylindrical shape, place it in a sleeve, cover the cap, and press the heavy weight once; take out the specimen, and under the condition of not touching the anti-counterfeiting feature part, flatten the specimen, observe the loss of anti-counterfeiting features and record the crease times of the specimen in sequence; then rotate the specimen by 90 degrees and repeat step b. After the four sides of the front are completed, repeat the above steps on the reverse side of the specimen, and alternate like this until the end point of the crease operation. To meet the usage performance requirements of the paper, the present invention requires that the crease resistance times should be higher than 18 times. After testing, the anti-counterfeiting watermark papers prepared in Examples 5-7 all meet the above requirements.

[0056] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

Claims

1. An anti-counterfeiting watermark paper, characterized in that: It includes base paper and an anti-counterfeiting film, and the anti-counterfeiting film is made through the following steps: Step S1: After bleaching jute fibers, disperse them in deionized water, add sodium bromide and an oxidant, stir evenly, then add a 15% sodium hypochlorite solution by mass fraction, stir evenly at a constant speed and react. During the reaction process, add a 10% sodium hydroxide solution by mass fraction dropwise to maintain pH = 10.5 until the pH value no longer decreases, and add absolute ethanol dropwise to terminate the reaction. Obtain a slurry, wash it by centrifugation with deionized water until the washing liquid is neutral, and homogenize it to obtain a cellulose nanofiber hydrogel. Control the dosage ratio of jute fibers, sodium bromide, oxidant, sodium hypochlorite solution and absolute ethanol to be 5 - 8 g∶0.5 - 0.6 g∶0.1 - 0.15 g∶40.5 - 42.8 g∶2 - 3 mL; Step S2: Add sodium molybdate to deionized water, stir evenly until it dissolves, add a 10% sodium hydroxide aqueous solution by mass fraction dropwise to adjust the pH until pH = 6, then add it and a 1% L-cysteine aqueous solution by mass fraction to a reaction kettle, heat up to 200 °C, keep the temperature for reaction for 12 h, cool to room temperature after the reaction ends, take it out, centrifuge at 10000 r / min for 15 min, collect the supernatant, dialyze it through a dialysis bag with a molecular weight cut-off of 3600 for 6 h, and then dry it in vacuum at 55 °C for 6 h to obtain molybdenum disulfide quantum dots. Control the dosage ratio of sodium molybdate and deionized water to be 0.12 - 0.15 g∶12 - 15 mL, and the weight ratio of sodium molybdate and L-cysteine to be 1∶2; Step S3: Add the obtained molybdenum disulfide quantum dots to deionized water, stir evenly for 30 min, then add a 0.5 mmol / L tryptophan solution dropwise, stir magnetically for 30 min, then seal and heat up to 80 °C, continue to stir and react for 12 h to obtain enhanced molybdenum disulfide quantum dots. Control the dosage ratio of molybdenum disulfide quantum dots, deionized water and tryptophan solution to be 0.05 - 0.08 g∶0.5 mL∶3 mL; Step S4: Add the cellulose nanofiber hydrogel to deionized water, stir evenly for 30 min, then add the enhanced molybdenum disulfide quantum dots, continue to stir for 30 min, add a 30% gelatin aqueous solution by mass fraction, stir evenly to form a mixed solution, uniformly coat it on the surface of a template, and dry it to make an anti-counterfeiting film. Control the weight ratio of cellulose nanofiber hydrogel, deionized water, enhanced molybdenum disulfide quantum dots and gelatin to be 2 - 3∶100∶0.2 - 0.5∶10 - 15.

2. The manufacturing method of an anti-counterfeiting watermark paper according to claim 1, characterized in that: It includes the following steps: After processing the anti-counterfeiting film, add it to the pulp through a directional release device to distribute it directionally in the paper. The application amount of the anti-counterfeiting film is 0.3 - 1% of the paper area.