Process for preventing ink from fading on a surface
By printing alkenylated magnetic ink on a thiol-functionalized polyolefin film substrate and performing an alkenyl-thiol click reaction, the problem of insufficient bonding strength of traditional surface printing inks is solved, and a surface printing process with high adhesion and magnetic anti-counterfeiting properties is achieved to prevent ink fading.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU ZIJIN PLASTIC
- Filing Date
- 2026-04-08
- Publication Date
- 2026-06-02
AI Technical Summary
The limited interfacial bonding strength between traditional surface printing inks and the substrate makes the image and text areas prone to quality defects such as scratches, ink fading, and color fading. Furthermore, the application needs of magnetic anti-counterfeiting inks in the anti-counterfeiting field have not been met.
Alkenylated magnetic ink is gravure printed onto a mercapto-functionalized polyolefin film substrate, and an alkenyl-mercapto-click reaction is carried out under ultraviolet light to achieve a chemical bond between the ink and the substrate.
It significantly improves the adhesion between ink and substrate, prevents discoloration, and has a magnetic anti-counterfeiting effect. The ink adhesion reaches over 98.0%, and it does not discolor after treatment with water, anhydrous ethanol, or rubbing.
Smart Images
Figure SMS_3 
Figure QLYQS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of ink surface printing technology, specifically to an ink fading prevention surface printing process. Background Technology
[0002] Surface printing (abbreviated as surface printing) is a process that directly prints ink onto the surface of a substrate to form graphic markings. It is widely used in the printing and processing of plastic flexible packaging materials such as BOPP film.
[0003] The main surface printing methods include offset printing, flexographic printing, gravure printing, screen printing, and inkjet printing. Among them, gravure printing has become one of the mainstream surface printing methods in the flexible packaging field due to its advantages such as high print quality, rich color reproduction, wide compatibility with printing materials, thick ink layer with strong weather resistance, and high production efficiency.
[0004] However, traditional surface printing inks typically adhere to the printing substrate through physical processes (mechanical bonding, hydrogen bonds, van der Waals forces, etc.). The interfacial bonding strength between the ink layer and the printing substrate is limited, which leads to quality defects such as scratches, ink fading, and color loss in the graphic areas during transportation, handling, and repeated handling by end consumers.
[0005] In addition, to protect brand rights, prevent the circulation of counterfeit and shoddy products, and safeguard consumer safety and market order, the application of magnetic anti-counterfeiting ink has become an important development trend in the packaging and printing industry. Summary of the Invention
[0006] This invention provides a surface printing process to prevent ink fading. It utilizes a gravure printing method to print a self-developed alkenylated magnetic ink onto a mercapto-functionalized polyolefin film substrate. Under ultraviolet light, the ink and substrate are chemically bonded together through an alkenyl-mercaptoclick reaction, achieving the beneficial technical effects of significantly improving the adhesion between the ink and the substrate and preventing ink fading.
[0007] A surface printing process to prevent ink fading: the process involves printing alkenylated magnetic ink onto a mercapto-functionalized polyolefin film substrate using gravure printing, and fixing the ink to the substrate through an alkenyl-mercapto click reaction under ultraviolet light to obtain an ink-fading resistant surface printed product.
[0008] The preparation method of the alkenylated magnetic ink is as follows: the alkenylated siloxane-type polyurethane binder is compounded with hydrophilic iron oxide magnetic pigment through silanol-hydroxyl condensation reaction, and a compounding agent and water are added to obtain the alkenylated magnetic ink.
[0009] The preparation method of the alkenyl siloxane type polyurethane binder is as follows: using isophorone diisocyanate and polycaprolactone diol as the basic reactive monomers, alkenyl siloxane type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine as composite chain extenders, the alkenyl siloxane type polyurethane binder is prepared through stepwise addition polymerization reaction and high-speed shear emulsification process;
[0010] Preferably, the preparation method of the alkenyl siloxane-type hydroxyl chain extender is as follows:
[0011] An intermediate is generated by an addition reaction between the phenolic hydroxyl functional group of 1 molar equivalent of p-hydroxyacetophenone and the isocyanate group of 1.01-1.05 molar equivalent of 3-isocyanopropyltrimethoxysilane.
[0012] An alkenyl siloxane-type hydroxyl chain extender is generated by reacting diethanolamine with an intermediate containing α-H and 10-undecenal via a Mannich condensation reaction, with the molar ratio of diethanolamine, intermediate and 10-undecenal controlled at 1:1:1.01-1.05.
[0013] Preferably, the molar ratio of isophorone diisocyanate, polycaprolactone diol, alkenylsiloxane-type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate, and ethylenediamine in the alkenylsiloxane-type polyurethane binder is 2.05:1:0.1-0.3:0.4-0.6:0.1:0.2.
[0014] Preferably, the composite additives include defoamers, leveling agents, and photoinitiators.
[0015] Preferably, the formulation of the alkenylated magnetic ink is: 30-45 parts by weight of alkenylated siloxane-type polyurethane binder, 5-15 parts by weight of hydrophilic iron oxide magnetic pigment, 0.1-1 parts by weight of defoamer, 0.5-2 parts by weight of leveling agent, 0.01-0.08 parts by weight of photoinitiator and 5-15 parts by weight of water.
[0016] Preferably, the average particle size of the hydrophilic iron oxide magnetic pigment is 100-200 nm.
[0017] Preferably, the method for preparing the thiol-functionalized polyolefin film substrate is as follows:
[0018] Plasma corona treatment was performed on the surface of a polyolefin film substrate with dimensions of 100mm×200mm and a thickness of 40-70μm. The treatment power was 70-90W, the treatment time was 15-25s, and the treatment distance was 5-10mm to obtain a polyolefin film substrate with a surface rich in hydroxyl groups.
[0019] The silanol functional group obtained by hydrolyzing 3-8 parts by weight of mercaptopropyltrimethoxysilane undergoes a dehydration condensation reaction with the hydroxyl functional group on the surface of a polyolefin membrane substrate rich in hydroxyl groups, thereby modifying the surface of the polyolefin membrane substrate with mercaptopropyltrimethoxysilane to obtain a mercaptofunctionalized polyolefin membrane substrate.
[0020] Preferably, the polyolefin film substrate is one of BOPP film, PP film, BOPE film, and PE film;
[0021] Preferably, the method for preparing the ink-resistant surface-printed product is as follows:
[0022] Alkenylated magnetic ink is injected into the ink trough of a gravure printing press and evenly coated onto the surface of the printing plate cylinder by the inking roller. The printing plate cylinder is rotated to the position of the doctor blade, and the doctor blade is used to scrape off the excess ink in the non-image areas, leaving only the ink in the recessed cells. The angle of the doctor blade is set to 30-50° and the pressure is set to 1.5-2.5 bar. A mercapto-functionalized polyolefin film substrate is installed, and the printing plate cylinder carrying the ink is rolled against the impression cylinder to form clear images on the surface of the substrate. The impression pressure is set to 5-8 bar to obtain the pre-printed mercapto-functionalized polyolefin film substrate.
[0023] The pre-printed mercapto-functionalized polyolefin film substrate was irradiated under ultraviolet light for 1 minute. The ultraviolet light wavelength was 360 nm and the power density was 10-20 mW / cm². 2 The irradiation distance is 8-12cm, and then the product is baked in a 70-90℃ electric constant temperature drying oven for 20-40 minutes to obtain anti-ink fading surface printing products.
[0024] Beneficial effects:
[0025] Based on the principle of molecular design, this invention uses p-hydroxyacetophenone, 3-isocyanate-propyltrimethoxysilane, diethanolamine and 10-undecenal as raw materials to prepare an alkenylated siloxane-type hydroxy chain extender through phenolic hydroxy-isocyanate group addition reaction and Mannich condensation reaction.
[0026] Using isophorone diisocyanate and polycaprolactone diol as basic reactive monomers, and alkenyl siloxane-type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine as composite chain extenders, alkenyl siloxane-type polyurethane binder was prepared through stepwise addition polymerization and high-speed shear emulsification process.
[0027] Alkenylated siloxane-type polyurethane binder is compounded with hydrophilic iron oxide magnetic pigment through silanol-hydroxyl condensation reaction, and then defoamer, leveling agent, photoinitiator and water are added to obtain alkenylated magnetic ink.
[0028] Using BOPP film as the polyolefin film substrate, the BOPP film is first surface-treated with corona treatment and mercaptopropyltrimethoxysilane to obtain a mercapto-functionalized BOPP film. Then, alkenylated magnetic ink is printed on the surface of the mercapto-functionalized BOPP film by gravure printing. Finally, under the action of ultraviolet light, the ink and the substrate are chemically bonded together through alkenyl-mercaptoclick reaction. After drying, an ink-resistant surface-printed product is obtained with an ink adhesion of >98.0%, and the ink does not fade after water treatment at 25°C for 24 hours, anhydrous ethanol treatment at 25°C for 24 hours, and 100 rubs.
[0029] The ink on the anti-ink fading surface-printed products prepared by this invention can detect magnetic signals, thus possessing a magnetic anti-counterfeiting effect. Detailed Implementation
[0030] Example 1:
[0031] The preparation process of alkenylated siloxane-type polyurethane binder I includes the following steps:
[0032] (1) Preparation of alkenyl siloxane-type hydroxyl chain extender, the preparation steps are as follows:
[0033] Step 1: An addition reaction occurs between the phenolic hydroxyl functional group of 1 molar equivalent of p-hydroxyacetophenone and the isocyanate group of 1.02 molar equivalent of 3-isocyanopropyltrimethoxysilane to generate an intermediate, the chemical structural formula of which is:
[0034] ;
[0035] Step 2: A Mannich condensation reaction is carried out between diethanolamine and an intermediate containing α-H and 10-undecenal, with the molar ratio of diethanolamine, intermediate, and 10-undecenal controlled at 1:1:1.03, to generate an alkenyl siloxane-type hydroxyl chain extender with the following chemical structure:
[0036] ;
[0037] The specific experimental steps for preparing alkenyl siloxane-type hydroxyl chain extenders are as follows:
[0038] Under nitrogen protection, 2.8 g of p-hydroxyacetophenone and 20 mL of anhydrous N,N-dimethylformamide were added to a three-necked flask and stirred at room temperature until completely dissolved. Then, 4.0 mL of 3-isocyanopropyltrimethoxysilane and 2 drops of dibutyltin dilaurate catalyst were added dropwise to the three-necked flask. The mixture was heated to 60 °C and stirred for 8 h. After cooling to room temperature, the mixture was rotary evaporated under reduced pressure, washed with anhydrous ethanol, and dried to obtain the intermediate.
[0039] Under nitrogen protection, 1.1 g of diethanolamine, 3.4 g of intermediate, 1.7 g of 10-undecenal and 50 mL of anhydrous N,N-dimethylformamide were added to a three-necked flask equipped with a water separator. The mixture was stirred at room temperature for 30 min, heated to 80 °C and stirred for 24 h, cooled to room temperature, evaporated under reduced pressure, and dried to obtain an alkenyl siloxane-type hydroxyl chain extender.
[0040] The 1H NMR characterization of alkenylsiloxane-type hydroxyl chain extenders is as follows: 1 H NMR (DMSO-d6, 400MHz) δ: 0.61-0.65 (t, 2H), 1.22-1.42 (m, 12H), 1.60-1.80 (m, 4H), 2.01-2.06 (m, 2H), 2.87-3.01 (m, 6H), 3.18-3.29 (m, 3H), 3.52(s, 9H), 3.59-3.65(m, 4H), 3.82-3.86(t, 2H), 4.95-5.10(dd, 2H), 5.74-5.84(m, 2H), 7.44-7.84(m, 4H);
[0041] (2) Preparation of alkenyl siloxane type polyurethane binder I: isophorone diisocyanate and polycaprolactone diol are used as basic reactive monomers, alkenyl siloxane type hydroxy chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine are used as composite chain extenders, and the molar ratio of isophorone diisocyanate, polycaprolactone diol, alkenyl siloxane type hydroxy chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine is controlled to be 2.05:1:0.1:0.6:0.1:0.2. Alkenyl siloxane type polyurethane binder I is obtained through stepwise addition polymerization reaction and high-speed shear emulsification process;
[0042] The specific experimental steps for preparing alkenyl siloxane-type polyurethane binder I are as follows:
[0043] Under nitrogen protection, 9.1 g of isophorone diisocyanate, 20 g of polycaprolactone diol (model Mw~1000 g / mol, vacuum dried at 120℃ for 12 h before use) and 100 mL of anhydrous acetone were added to a three-necked flask and stirred at room temperature (500 rpm) for 30 min to dissolve. Two drops of dibutyltin dilaurate catalyst were added dropwise to the three-necked flask, and the temperature was raised to 80℃ and stirred until the NCO content in the system reached the theoretical value (the theoretical residual value of NCO groups calculated according to the stoichiometric ratio), thus obtaining the prepolymer solution.
[0044] First, maintain the temperature at 80℃, and add 10mL of anhydrous acetone solution containing 1.2g of alkenyl siloxane-type hydroxyl chain extender and 10mL of anhydrous acetone solution containing 1.1g of 1,4-butanediol dropwise to the prepolymer solution. After the addition is complete, continue stirring at 80℃ until the NCO content in the system reaches the theoretical value. Then, cool down to 30℃, add 50mL of acetone to adjust the viscosity, and slowly add 1mL of aqueous solution containing 0.4g of sodium ethylenediamine ethanesulfonate to a three-necked flask under high-speed stirring (2000rpm). Maintain the temperature at 30℃ and stir for 10min. Then, add 100mL of deionized water for high-speed dispersion and emulsification for 20min. Finally, add 5mL of aqueous solution containing 0.3g of ethylenediamine and stir for 15min. Remove acetone by rotary evaporation to obtain alkenyl siloxane-type polyurethane binder I.
[0045] The NCO content was determined according to the standard HG / T 2409-1992 "Determination of Isocyanate Group Content in Polyurethane Prepolymer".
[0046] Example 2:
[0047] The preparation process of alkenylsiloxane-type polyurethane binder II was the same as that of alkenylsiloxane-type polyurethane binder I, with the only difference being that the molar ratio of isophorone diisocyanate, polycaprolactone diol, alkenylsiloxane-type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate, and ethylenediamine was 2.05:1:0.2:0.5:0.1:0.2 (i.e., 2.4g of alkenylsiloxane-type hydroxyl chain extender was used to replace 1.2g of alkenylsiloxane-type hydroxyl chain extender, and 0.9g of 1,4-butanediol was used to replace 1.1g of 1,4-butanediol).
[0048] Example 3:
[0049] The preparation process of alkenylsiloxane-type polyurethane binder III was the same as that of alkenylsiloxane-type polyurethane binder I, with the only difference being that the molar ratio of isophorone diisocyanate, polycaprolactone diol, alkenylsiloxane-type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate, and ethylenediamine was 2.05:1:0.3:0.4:0.1:0.2 (i.e., 3.6g of alkenylsiloxane-type hydroxyl chain extender was used to replace 1.2g of alkenylsiloxane-type hydroxyl chain extender, and 0.7g of 1,4-butanediol was used to replace 1.1g of 1,4-butanediol).
[0050] Example 4:
[0051] An alkenylated magnetic ink was prepared with the following formulation: 40 parts by weight of alkenylated siloxane-type polyurethane binder, 10 parts by weight of hydrophilic iron oxide magnetic pigment, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent, 0.05 parts by weight of photoinitiator, and 10 parts by weight of water. The preparation method was as follows: first, the silanol functional groups obtained by the hydrolysis reaction of the siloxane groups in the alkenylated siloxane-type polyurethane binder undergo a dehydration condensation reaction with the hydroxyl functional groups abundant on the surface of the hydrophilic iron oxide magnetic pigment, thereby achieving chemical bonding and composite formation between the alkenylated functionalized polyurethane binder and the iron oxide magnetic pigment; then, the defoamer, leveling agent, photoinitiator, and water were added to obtain the alkenylated magnetic ink.
[0052] The specific experimental steps for preparing alkenylated magnetic ink are as follows: 40g of alkenylated siloxane-type polyurethane binder and 10g of hydrophilic iron oxide magnetic pigment (average particle size of 150nm) are mixed and dispersed at 1500r / min for 20min. The mixture is then ground and dispersed using a sand mill for 1h. The speed is reduced to 500r / min, and 0.5g of defoamer (model BYK-024), 1g of leveling agent (model BYK-346), 0.05g of photoinitiator (model 2959) and 10g of water are added. The mixture is defoamed at low speed for 20min and stirred evenly to obtain alkenylated magnetic ink.
[0053] When the alkenylated siloxane polyurethane binders are alkenylated siloxane polyurethane binders I, II, and III respectively, alkenylated magnetic inks I, II, and III are prepared accordingly.
[0054] Example 5:
[0055] A surface printing process to prevent ink fading includes the following steps:
[0056] Step 1: Preparation of BOPP film with hydroxyl-rich surface: Using BOPP film (thickness of 50μm) as the printing substrate, the surface of the BOPP film is subjected to plasma corona treatment with a treatment power of 80W, a treatment time of 20s, and a treatment distance of 8mm to obtain BOPP film with hydroxyl-rich surface.
[0057] Step 2, preparation of mercapto-functionalized BOPP film: The silanol functional groups obtained by hydrolysis of mercaptopropyltrimethoxysilane (silane coupling agent KH-590) undergo a dehydration condensation reaction with the hydroxyl functional groups abundant on the surface of the BOPP film, thereby modifying the surface of the BOPP film with mercaptopropyltrimethoxysilane to obtain a mercapto-functionalized BOPP film. The preparation steps are as follows: 5g of mercaptopropyltrimethoxysilane (silane coupling agent KH-590), 45mL of anhydrous ethanol and 5mL of deionized water are mixed evenly and stirred at room temperature for 2h to obtain a hydrolysate of mercaptopropyltrimethoxysilane. Then, the BOPP film (size 100mm×200mm) with hydroxyl-rich surface is immersed in the hydrolysate of mercaptopropyltrimethoxysilane, heated to 40℃ and soaked for 5h. After removal, it is repeatedly washed with anhydrous ethanol and dried to obtain the mercapto-functionalized BOPP film.
[0058] Step 3: Preparation of the preliminarily printed thiol-functionalized BOPP film: Inject alkenylated magnetic ink into the ink trough of the gravure printing press, and evenly coat it on the surface of the printing plate cylinder through the inking roller. Rotate the printing plate cylinder to the position of the doctor blade, and use the doctor blade to scrape off the excess ink in the non-image areas, leaving only the ink in the recessed cells. The angle of the doctor blade is set to 40° and the pressure is set to 2.0 bar. Install the thiol-functionalized BOPP film (size 100mm×200mm), and roll the printing plate cylinder carrying the ink against the impression cylinder to form a clear image on the substrate surface. The impression pressure is set to 6 bar to obtain the preliminarily printed thiol-functionalized BOPP film.
[0059] Step 4, Preparation of Anti-Ink Fading Surface Printed Products: The magnetic ink is chemically bonded to the BOPP film surface through a click reaction between the alkenyl functional groups in the alkenylated magnetic ink and the thiol functional groups in the thiol-functionalized BOPP film under ultraviolet light. After drying, the anti-ink fading surface printed product is obtained. The preparation steps are as follows: The preliminarily printed thiol-functionalized BOPP film is irradiated under ultraviolet light for 1 minute. The ultraviolet light wavelength is 360 nm and the power density is 15 mW / cm². 2 The irradiation distance is 10cm, and then it is baked in an 80℃ electric heating constant temperature drying oven for 30 minutes to obtain the ink-resistant surface printing product.
[0060] When the alkenylated magnetic inks are alkenylated magnetic inks I, II, and III respectively, anti-ink fading surface printing products I, II, and III are prepared accordingly.
[0061] Comparative example:
[0062] A conventional ink surface printing process includes the following steps:
[0063] Step 1: Preparation of BOPP film with hydroxyl-rich surface: Using BOPP film (thickness of 50μm) as the printing substrate, the surface of the BOPP film is subjected to plasma corona treatment with a treatment power of 80W, a treatment time of 20s, and a treatment distance of 8mm to obtain BOPP film with hydroxyl-rich surface.
[0064] Step 2, Preparing the Preliminary Printed BOPP Film: Conventional magnetic ink is injected into the ink trough of the gravure printing press and evenly coated onto the surface of the printing plate cylinder via the inking roller. The printing plate cylinder is rotated to the position of the doctor blade, which scrapes away excess ink from non-image areas, leaving only the ink in the recessed cells. The doctor blade angle is set to 40° and the pressure to 2.0 bar. A BOPP film (100mm × 200mm) with hydroxyl-rich surfaces is then mounted. The ink-laden printing plate cylinder is rolled against the impression cylinder to form a clear image on the substrate surface. The impression pressure is set to 6 bar, resulting in the preliminary printed BOPP film.
[0065] Step 3, Preparation of conventional ink surface-printed products: Place the preliminarily printed BOPP film in an 80℃ electric heating constant temperature drying oven and bake for 30 minutes to obtain conventional ink surface-printed products;
[0066] The formula for the conventional magnetic ink is as follows: 40 parts by weight of conventional polyurethane binder, 10 parts by weight of hydrophilic iron oxide magnetic pigment, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent, and 10 parts by weight of water. The preparation steps are as follows: 40g of conventional polyurethane binder and 10g of hydrophilic iron oxide magnetic pigment (average particle size of 150nm) are mixed and dispersed at 1500r / min for 20min. The mixture is then ground and dispersed using a sand mill for 1h. The speed is reduced to 500r / min, and 0.5g of defoamer (model BYK-024), 1g of leveling agent (model BYK-346), and 10g of water are added. The mixture is defoamed at low speed for 20min and stirred evenly to obtain the conventional magnetic ink.
[0067] The conventional polyurethane binder is prepared by using isophorone diisocyanate and polycaprolactone diol as the basic reactive monomers, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine as composite chain extenders, and controlling the molar ratio of isophorone diisocyanate, polycaprolactone diol, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine to be 2.05:1:0.7:0.1:0.2. The conventional polyurethane binder is obtained through stepwise addition polymerization and high-speed shear emulsification.
[0068] The specific preparation steps of conventional polyurethane binders are the same as those of the preparation experiment of alkenyl siloxane type polyurethane binder I. The only difference is that 1.3g of 1,4-butanediol is used to replace 1.2g of alkenyl siloxane type hydroxyl chain extender and 1.1g of 1,4-butanediol.
[0069] Performance testing:
[0070] I. Adhesion performance test: The adhesion of the ink layer in the anti-fading ink surface-printed products was tested according to the disc peel method in GB / T 13217.7-2023 "Ink Adhesion Test Method".
[0071] II. Anti-fading performance test:
[0072] (1) Immerse half of the anti-ink fading surface printing product (size 100mm×200mm) in water (25℃) for 24 hours, take it out and air dry at room temperature, and observe whether the ink on the anti-ink fading surface printing product is fading.
[0073] (2) Immerse half of the anti-ink fading surface printing product (size 100mm×200mm) in anhydrous ethanol (25℃) for 24h, take it out and air dry at room temperature, and observe whether the ink on the anti-ink fading surface printing product is fading.
[0074] (3) Fix the anti-ink fading surface printed product (size 100mm×200mm) on the table of the arc abrasion tester, fix the unprinted BOPP film (size 60mm×100mm) on the grinding head as the friction material, set the number of friction times to 100 times and the friction speed to 30 times / min, place a 300g weight on the grinding head, and observe whether the ink on the anti-ink fading surface printed product is fading.
[0075] III. Magnetic Response Performance Test: A miniature magnetic banknote detector is used to test the magnetic response performance of the ink on the anti-fading ink printed product. The ink layer is rubbed with a magnetic head to detect whether there is a magnetic signal, thereby characterizing the magnetic anti-counterfeiting effect of the ink.
[0076] The test results are shown in Table 1 below.
[0077] Table 1. Performance test results of ink fading resistant printed products
[0078] The following conclusions can be drawn from a comprehensive analysis of the performance test results:
[0079] Conclusion 1: This invention utilizes independently developed alkenylated magnetic ink to perform surface printing treatment on polyolefin film substrate (BOPP film) through an ink-resistant fading surface printing process. The resulting ink-resistant fading surface-printed products have achieved significant improvements in both ink adhesion performance and fading resistance.
[0080] Conclusion 2: The ink on the anti-ink fading surface-printed products prepared by this invention can detect magnetic signals, thus possessing magnetic anti-counterfeiting effects.
Claims
1. A surface printing process to prevent ink fading, characterized in that, The process is as follows: alkenylated magnetic ink is printed onto a mercapto-functionalized polyolefin film substrate by gravure printing, and the ink and substrate are fixed by alkenyl-mercapto click reaction under ultraviolet light to obtain an ink-resistant surface-printed product. The preparation method of the alkenylated magnetic ink is as follows: the alkenylated siloxane-type polyurethane binder is compounded with hydrophilic iron oxide magnetic pigment through silanol-hydroxyl condensation reaction, and a compounding agent and water are added to obtain the alkenylated magnetic ink. The preparation method of the alkenyl siloxane type polyurethane binder is as follows: using isophorone diisocyanate and polycaprolactone diol as the basic reactive monomers, alkenyl siloxane type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate and ethylenediamine as composite chain extenders, the alkenyl siloxane type polyurethane binder is prepared through stepwise addition polymerization reaction and high-speed shear emulsification process; The chemical structural formula of the alkenyl siloxane-type hydroxyl chain extender is as follows: 。 2. The anti-ink fading surface printing process according to claim 1, characterized in that, The preparation method of the alkenyl siloxane-type hydroxyl chain extender is as follows: An intermediate is generated by an addition reaction between the phenolic hydroxyl functional group of 1 molar equivalent of p-hydroxyacetophenone and the isocyanate group of 1.01-1.05 molar equivalent of 3-isocyanopropyltrimethoxysilane. An alkenyl siloxane-type hydroxyl chain extender is generated by reacting diethanolamine with an intermediate containing α-H and 10-undecenal via a Mannich condensation reaction, with the molar ratio of diethanolamine, intermediate and 10-undecenal controlled at 1:1:1.01-1.
05.
3. The anti-ink fading surface printing process according to claim 1, characterized in that, The molar ratio of isophorone diisocyanate, polycaprolactone diol, alkenylsiloxane-type hydroxyl chain extender, 1,4-butanediol, sodium ethylenediamine ethanesulfonate, and ethylenediamine in the alkenylsiloxane-type polyurethane binder is 2.05:1:0.1-0.3:0.4-0.6:0.1:0.
2.
4. The anti-ink fading surface printing process according to claim 1, characterized in that, The composite additives include defoamers, leveling agents, and photoinitiators.
5. The anti-ink fading surface printing process according to claim 4, characterized in that, The formulation of the alkenylated magnetic ink is as follows: 30-45 parts by weight of alkenylated siloxane-type polyurethane binder, 5-15 parts by weight of hydrophilic iron oxide magnetic pigment, 0.1-1 parts by weight of defoamer, 0.5-2 parts by weight of leveling agent, 0.01-0.08 parts by weight of photoinitiator and 5-15 parts by weight of water.
6. The anti-ink fading surface printing process according to claim 5, characterized in that, The average particle size of the hydrophilic iron oxide magnetic pigment is 100-200 nm.
7. The anti-ink fading surface printing process according to claim 1, characterized in that, The method for preparing the mercapto-functionalized polyolefin film substrate is as follows: Plasma corona treatment was performed on the surface of a polyolefin film substrate with dimensions of 100mm×200mm and a thickness of 40-70μm. The treatment power was 70-90W, the treatment time was 15-25s, and the treatment distance was 5-10mm to obtain a polyolefin film substrate with a surface rich in hydroxyl groups. The silanol functional group obtained by hydrolyzing 3-8 parts by weight of mercaptopropyltrimethoxysilane undergoes a dehydration condensation reaction with the hydroxyl functional group on the surface of a polyolefin membrane substrate rich in hydroxyl groups, thereby modifying the surface of the polyolefin membrane substrate with mercaptopropyltrimethoxysilane to obtain a mercaptofunctionalized polyolefin membrane substrate.
8. The anti-ink fading surface printing process according to claim 7, characterized in that, The polyolefin film substrate is one of BOPP film, PP film, BOPE film, and PE film.
9. The anti-ink fading surface printing process according to claim 1, characterized in that, The preparation method of the anti-ink fading surface printing product is as follows: Alkenylated magnetic ink is injected into the ink trough of a gravure printing press and evenly coated onto the surface of the printing plate cylinder by the inking roller. The printing plate cylinder is rotated to the position of the doctor blade, and the doctor blade is used to scrape off the excess ink in the non-image areas, leaving only the ink in the recessed cells. The angle of the doctor blade is set to 30-50° and the pressure is set to 1.5-2.5 bar. A mercapto-functionalized polyolefin film substrate is installed, and the printing plate cylinder carrying the ink is rolled against the impression cylinder to form clear images on the surface of the substrate. The impression pressure is set to 5-8 bar to obtain the pre-printed mercapto-functionalized polyolefin film substrate. The pre-printed mercapto-functionalized polyolefin film substrate was irradiated under ultraviolet light for 1 minute. The ultraviolet light wavelength was 360 nm and the power density was 10-20 mW / cm². 2 The irradiation distance is 8-12cm, and then the product is baked in a 70-90℃ electric constant temperature drying oven for 20-40 minutes to obtain anti-ink fading surface printing products.