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CN-121975370-A - Preparation method of printing ink with high water resistance

CN121975370ACN 121975370 ACN121975370 ACN 121975370ACN-121975370-A

Abstract

The invention relates to the technical field of printing ink preparation, in particular to a preparation method of high-water-resistance printing ink, which comprises the steps of taking 50-80 parts of self-crosslinking aqueous polyurethane resin, adding 3-8 parts of silane coupling agent and 2-5 parts of hydroxyl-terminated polydimethylsiloxane, stirring for 1.5-3 hours, adding 1-4 parts of amino modified nano silicon dioxide, performing ultrasonic dispersion to obtain amphiphilic modified resin, adding 15-30 parts of pigment, adding 1-3 parts of titanate coupling agent, stirring, adding mica powder and dispersing agent to obtain core-shell pigment filler dispersion liquid, adding 5-12 parts of polyvinylidene fluoride emulsion, adding 2-6 parts of perfluoroalkyl ethyl acrylate copolymer, stirring, adding an antifoaming agent and an ultraviolet absorbent to obtain interpenetrating network function auxiliary agent liquid, adding pigment filler dispersion liquid into the amphiphilic modified resin, stirring at 60-80 ℃ and introducing nitrogen, adding auxiliary agent liquid for crosslinking in a plurality of times, dripping thickener, and filtering to obtain the high-water-resistance printing ink. The ink prepared by the invention has excellent water resistance, stable storage, small viscosity change, suitability for multiple scenes, chemical corrosion resistance and ultraviolet aging resistance, smooth printing, uniform film formation, environmental protection and convenient industrial production, and is not easy to fall off and swell.

Inventors

  • FENG MINGJIE

Assignees

  • 宁波市菲比印务有限公司

Dates

Publication Date
20260505
Application Date
20260402

Claims (10)

  1. 1. The preparation method of the printing ink with high water resistance is characterized by comprising the following steps of: S1, preparing amphiphilic modified resin, namely taking 50-80 parts of self-crosslinking aqueous polyurethane resin, adding 3-8 parts of silane coupling agent and 2-5 parts of hydroxyl-terminated polydimethylsiloxane into the resin, placing a mixed system in a 70-90 ℃ environment, stirring for 1.5-3 hours, reacting double bonds in molecules of the silane coupling agent with hydroxyl groups in the aqueous polyurethane resin during the period, then adding 1-4 parts of amino modified nano silicon dioxide, wherein the particle size of the nano silicon dioxide is 10-30nm, the amino content is 3-5mmol/g, reacting amino in molecules of the nano silicon dioxide with carboxyl in the aqueous polyurethane resin, placing the mixed system into ultrasonic equipment, and performing ultrasonic dispersion for 20-40 minutes through power of 300-500W to obtain the amphiphilic modified resin; S2, preparing pigment filler with a core-shell structure, namely taking 15-30 parts of pigment, wherein the pigment is carbon black or titanium white, adding 1-3 parts of titanate coupling agent into the pigment, stirring for 1 hour, adding 5-15 parts of mica powder, adding 2-6 parts of polycarboxylate dispersing agent, adding the mixed system into deionized water, stirring for 30-60 minutes, and then transferring the mixed system to a sand mill to obtain core-shell pigment filler dispersion liquid; S3, preparing an interpenetrating network function auxiliary agent, namely taking 5-12 parts of polyvinylidene fluoride emulsion with the solid content of 30-50%, adding 2-6 parts of perfluoroalkyl ethyl acrylate copolymer with the fluorine content of 20-40%, placing the mixed system in a 40-60 ℃ environment, stirring for 1 hour, adding 1-3 parts of polyether modified silicone oil defoamer and 0.5-2 parts of benzotriazole ultraviolet absorbent UV-327, and continuing stirring for 30-60 minutes, wherein the perfluoroalkyl ethyl acrylate copolymer and polyvinylidene fluoride form an interpenetrating network structure, so as to obtain the interpenetrating network function auxiliary agent liquid; S4, crosslinking and mixing an ink main body, namely adding the core-shell pigment and filler dispersion liquid prepared by S2 into the amphiphilic modified resin prepared by S1, placing the mixed system in an environment of 60-80 ℃, stirring for 2-4 hours, continuously introducing nitrogen in the stirring process, and adding the interpenetrating network function auxiliary liquid prepared by S3 into the mixed system for 3-5 times, wherein each time, the adding interval is 20-30 minutes, so as to obtain an ink premix; S5, post-treatment and performance regulation, namely placing the ink premix into ultrasonic equipment, performing ultrasonic defoaming for 15-30 minutes at the power of 200-400W, preparing 5-10% aqueous solution by using a hydroxyethyl cellulose thickener, dropwise adding the aqueous solution into the ink premix at the speed of 5-10mL/min, stirring while dropwise adding, measuring the pH value of an ink system, adding 0.1-0.5 part of triethanolamine or acetic acid for regulation if the pH value deviates from the range of 6.5-7.5, and filtering the regulated ink system through a filter membrane with the aperture of 0.1-0.5 mu m to obtain the high-water-resistance printing ink.
  2. 2. The method for preparing the high water-resistant printing ink according to claim 1, further comprising a step of S1-1 modified resin post-crosslinking, wherein the amphiphilic modified resin prepared in the step S1 is transferred to an oven, the temperature of the oven is set to be 60-70 ℃, and the amphiphilic modified resin is subjected to heat preservation treatment for 1-1.5 hours.
  3. 3. The method for preparing the high water-resistant printing ink according to claim 1, further comprising the step of regulating and controlling the surface hydroxyl groups of the S2-1 pigment and filler, wherein after the core-shell pigment and filler dispersion liquid is prepared in the step S2, 0.5-2 parts of gamma-glycidoxypropyl trimethoxysilane KH-560 is added into the dispersion liquid, and the mixed system is placed in an environment of 40-50 ℃ and stirred for 30 minutes.
  4. 4. The preparation method of the high water resistance printing ink according to claim 1, wherein the perfluoroalkyl ethyl acrylate copolymer in S3 is subjected to pretreatment, wherein the perfluoroalkyl ethyl acrylate copolymer is mixed with deionized water according to a mass ratio of 1:5 of the perfluoroalkyl ethyl acrylate copolymer, 0.1-0.3 part of acetic acid is added into the mixed solution, the pH value of the mixed solution is regulated to 4.0-5.0, the regulated mixed solution is placed in a room temperature environment and stirred for 30 minutes, and after the pretreatment is completed, the water contact angle of the interpenetrating network function auxiliary agent liquid on the surface of the PET substrate is measured.
  5. 5. The preparation method of the high water-resistant printing ink according to claim 1, wherein the nitrogen protection process in the step S4 is to strictly control the oxygen content, the nitrogen purity of the mixed system is monitored in real time through a nitrogen purity detector, and the prepared printing ink is stored for 6 months under the sealing condition of 25 ℃ after the nitrogen protection treatment.
  6. 6. The method for preparing the high water-resistant printing ink according to claim 1, wherein the dripping process of the hydroxyethyl cellulose thickener in the step S5 is matched with online viscosity monitoring, wherein a rotational viscometer is used for monitoring the viscosity change of an ink premix in real time, after each 1mL of hydroxyethyl cellulose aqueous solution is dripped, the dripping is stopped, the viscosity is measured, the dripping is continued after the viscosity data are stabilized, and finally the prepared ink is detected by a laser particle sizer.
  7. 7. The method for preparing the high water-resistant printing ink according to claim 1, wherein the amino content of the amino modified nano-silica in S1 is precisely controlled, if the amino content of the amino modified nano-silica exceeds 5mmol/g, 0.1-0.3 part of acetic acid is added into the mixed system, and after the neutralization reaction of the acetic acid and excessive amino is completed, the ph value of the mixed system is measured.
  8. 8. The method for preparing the printing ink with high water resistance according to claim 1, wherein the grinding parameters are optimized in the grinding process of S2, wherein a grinding mill adopts zirconium beads as a grinding medium, the particle size of the zirconium beads is selected to be 0.5-1mm, the rotating speed of the grinding mill is controlled to be 2000-3000rpm, the sample is sampled every 10 minutes in the grinding process, and the particle size of the sample is measured by using a laser particle sizer.
  9. 9. The preparation method of the high water resistance printing ink according to claim 1, wherein the benzotriazole ultraviolet absorbent UV-327 in S3 is subjected to pre-dispersion treatment, namely mixing and stirring the benzotriazole ultraviolet absorbent UV-327 and ethanol in a mass ratio of 1:10 until the ultraviolet absorbent is completely dissolved to obtain an ultraviolet absorbent ethanol solution, adding the solution into interpenetrating network function auxiliary liquid, and placing the solution into ultrasonic equipment to be dispersed for 10 minutes under 200W power.
  10. 10. The method for preparing the printing ink with high water resistance according to claim 1, wherein the step of adding water resistance pre-test is carried out after the step of S5 is carried out, wherein 10mL of the filtered printing ink is taken, the printing ink is uniformly printed on the surface of a PET substrate by using an applicator, the printing thickness is controlled to be 5-10 mu m, the printed substrate is put into an 80 ℃ oven for drying for 1 hour, the adhesive force of an ink layer is measured by a cross-cut method according to the GB/T9286-1998 standard after the drying, the adhesive force grade is required to be more than or equal to 4B, if the adhesive force grade is lower than 4B, 0.5-1 part of silane coupling agent is added to the residual printing ink, the step of stirring of the step of S4 is repeated, and the water resistance pre-test is carried out again after the filtering until the water resistance of the printing ink reaches the standard.

Description

Preparation method of printing ink with high water resistance Technical Field The invention relates to the technical field of printing ink preparation, in particular to a preparation method of high-water-resistance printing ink. Background The water resistance of the printing ink which is used as a key material in the fields of packaging, labels, publications and the like directly determines the service scene and service life of the product. Along with the expansion of application requirements of food packaging, outdoor advertising, daily chemical product labels and the like, the requirements of the market on the water resistance of the ink are more severe, namely, the ink layer is not required to be separated and is not subjected to halation after being soaked in the warm water, and the ink layer is required to be resistant to long-term storage and friction in a humid environment. However, the existing printing ink still faces a plurality of technical bottlenecks in improving the water resistance, and is difficult to meet the high-end application requirements. The current mainstream water-resistant printing ink mostly adopts water-based resin as a matrix, and organic fluorine or organic silicon waterproofing agents are added to realize the water-resistant function. Meanwhile, the traditional waterproof agent is mostly of a small molecular structure, has poor compatibility with a resin matrix, is easy to agglomerate in an ink system, cannot form a continuous and compact waterproof film, and can influence the printing smoothness and film forming uniformity of the ink. For example, after the organic fluorine waterproof agent is added into the conventional aqueous polyurethane ink, the water resistance can be temporarily improved, but the waterproof agent is easy to migrate to the surface of the ink layer after long-term soaking, so that the ink layer is cracked, and the problems of screen blocking, color difference and the like are easy to occur in the printing process. In the aspect of pigment and filler application, the traditional ink mostly directly uses unmodified pigment and filler, and the surface of the traditional ink contains a large number of hydrophilic groups such as hydroxyl groups and the like, is easy to combine with water molecules, and aggravates moisture absorption of an ink layer. Part of the technology attempts to carry out surface modification on the pigment and filler through the coupling agent, but the single coupling agent has limited modification effect, can only cover part of hydrophilic groups, has weak interfacial bonding force between the modified pigment and filler and a resin matrix, and is easy to peel under water soaking or external force friction, so that the ink layer is peeled off. In addition, the dispersibility of the pigment and filler also affects the water resistance, if not uniformly dispersed, pores are easily formed, and the pigment and filler become channels for water penetration, so that the water resistance of the ink layer is further reduced. Insufficient synergy of the functional auxiliary agents is also a key factor for restricting the water resistance. In the prior art, most of assistants such as waterproofing agents, defoaming agents, ultraviolet absorbers and the like are added independently, and the molecular-level cooperative design is lacked, so that the functions of the assistants are mutually interfered. For example, when an organofluorine waterproof agent is mixed with a polyether defoamer, delamination is likely to occur due to a difference in surface tension, and the waterproof effect is affected, and at the same time, if the ultraviolet absorber is unevenly dispersed, the ageing resistance of the ink layer is reduced, and the erosion of the ink layer by water is indirectly accelerated. In addition, the process control in the ink preparation process has defects, such as easy oxidation and bond breakage of the resin during high-temperature stirring, reduced crosslinking degree, large viscosity change during storage and further weakening of water resistance. From the application scene, the existing water-resistant ink has the problem of insufficient suitability, namely that when the water-resistant ink is used for food packaging, partial waterproofing agents possibly have migration risks and do not meet food safety standards, when the water-resistant ink is used for outdoor advertising, the water resistance and the ultraviolet resistance are difficult to be compatible, fading and skinning are easy to occur after long-term exposure, when the water-resistant ink is used for flexible packaging, the bending resistance of the ink layer is poor, cracks are easy to occur after bending, and moisture permeates through the cracks to cause the failure of the ink layer. The core of the problems is that the prior art can not construct a complete water-resistant system from multiple dimensions such as resin modification, pigment and filler structural design, auxil