High-weather-resistance ink for reflective film printing

Abstract

The invention discloses high-weather-resistance printing ink for reflective film printing. The printing ink is prepared from the following raw materials: a modified oligomer of urethane acrylate, a reactive diluent, an additive and water, the reactive diluent has a two-layer structure and comprises a shell layer and a core layer respectively; the shell layer is formed by taking polyvinyl alcohol as a protective colloid; the raw material of the core layer comprises one of a seed emulsion formed by isobornyl acrylate with a monofunctional group and a seed emulsion formed by tricyclodecane dimethyl alcohol diacrylate with a bifunctional group; and each seed emulsion also comprises butyl acrylate and methyl methacrylate. On the premise of improving the adhesion of the UV ink, the weather resistance of the UV ink is improved, and the service life of the UV ink in the using process is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of inks, in particular to a highly weather-resistant ink for printing on reflective films. Background Art

[0002] Reflective film is a thin film material made by applying the principle of retro-reflection. It can be widely used in the field of safety protection, including road traffic signs, reflective signs of vehicles, special work clothing, fire signs, railway signs, mining signs and other fields.

[0003] Many reflective films on the market are formed by spraying UV inks. UV printing technology is a new green digital printing technology developed in the late 1970s. The ultraviolet curing ink produced by this technology, referred to as UV ink, has the advantages of no volatile organic compounds (VOC), less environmental pollution, fast curing rate, energy saving, good performance of cured products, and suitable for high-speed automated production. In addition, because UV ink contains photosensitizers and has high viscosity, it can be cured by ultraviolet rays and can be sprayed and dried immediately.

[0004] However, when spraying patterns or logos on the reflective film, the UV ink becomes matte after curing, which is not smooth enough. This is because the reflective film has low interfacial free energy, poor surface affinity, and poor wettability of the ink on its surface, resulting in poor adhesion of the printed layer, shedding of the printed layer, and poor weather resistance. Therefore, most of today's UV inks use acrylic resin as a binder, and the primer is pre-coated on the surface of the reflective film, thereby solving the practical application problems of UV printing technology in the process of UV printing on reflective film, such as poor adhesion and easy shedding of the printed layer. However, in order to improve the weather resistance of UV ink based on the premise of improving the adhesion of the ink, the present application provides a solution. Summary of the invention

[0005] The present application provides a highly weather-resistant ink for printing on reflective film, which improves the weather resistance of UV ink and increases the life of UV ink during use while improving the adhesion of UV ink.

[0006] The present application provides a highly weather-resistant ink for printing on reflective film, wherein the raw materials of the ink include modified oligomers of polyurethane acrylate, active diluents, additives and water; the active diluent has a two-layer structure, including a shell layer and a core layer respectively; the shell layer is formed with polyvinyl alcohol as a protective colloid; the raw material of the core layer includes one of a seed emulsion formed with isobornyl acrylate having a monofunctional group and a seed emulsion formed with tricyclodecane dimethanol diacrylate having a difunctional group; each of the seed emulsions also includes butyl acrylate and methyl methacrylate.

[0007] By adopting the above technical scheme, the present application makes improvements in the preparation process of the active diluent in the process of improving the weather resistance of UV ink. Active diluent is a functional monomer. In UV catalytic ink, the diluting monomer dilutes and disperses the resin, reducing the viscosity of the resin to meet the requirements of the printing process. The present application uses polyvinyl alcohol to protect the shell of the colloid, and prepares the core layer of the active diluent of acrylate by seed emulsion polymerization. Polyvinyl alcohol has good compatibility with the resin during the preparation of UV ink, and can be efficiently processed to ensure that the reaction achieves a high conversion rate and reduce the amount of residual monomers in the system. And the seed emulsion in the seed emulsion of the present application has a monofunctional acrylate isobornyl ester or a difunctional tricyclodecane dimethanol diacrylate. The more reactive functional groups the active diluent contains, the faster the speed of the photocuring reaction, but due to the conversion of carbon-carbon double bonds into single bonds, the more serious the volume shrinkage of the cured film will be. The less functional the active diluent is, the lower its viscosity is, the stronger its dilution ability is, the fewer cross-linking points are, and the shrinkage of the cured film is reduced. Selecting a suitable active diluent according to the reflective film can further improve the weather resistance of the UV ink.

[0008] Preferably, the raw materials of the modified oligomer of polyurethane acrylate include polyurethane acrylate and a modification agent for polyurethane acrylate; the raw materials of the polyurethane acrylate include dicyclohexylmethane diisocyanate and polytetrahydrofuran.

[0009] Preferably, the modifying agent includes one or more of polydimethylsiloxane, polydiethylsiloxane, and dimethylphenylsilane.

[0010] By adopting the above technical scheme, the present application modifies polyurethane acrylate during the synthesis process through a modification reagent; since the isocyanate is first capped by the acrylate and then the long-chain diol is chain extended, the obtained oligomer has a narrow molecular weight and low viscosity, and the acrylate is easily polymerized if it is kept in the reactor for too long. To prevent the acrylate from being kept in the reactor for too long, the present application uses polydimethylsiloxane, polydiethylsiloxane, and dimethylphenylsilane as modification reagents, through silicone modification, and cooperates with polytetrahydrofuran as a polyether long-chain diol, which has high flexibility, thereby facilitating the synthesis of modified oligomers of polyurethane acrylate.

[0011] Preferably, the additives include a pigment, a thermal curing agent, a wetting agent and a photoinitiator; the thermal curing agent is aziridine, and the wetting agent is acetylene glycol.

[0012] By adopting the above technical solution, the thermal curing agent aziridine and the wetting agent acetylene glycol are coated on the reflective film coating. In the present application, aziridine and acetylene glycol are added to the UV ink as additives, wherein aziridine can improve the adhesion of the UV ink to the substrate; acetylene glycol helps leveling during the printing process, reduces bubbles, improves the adhesion durability and service life of the UV ink, and thus improves its weather resistance.

[0013] Preferably, the photoinitiator includes one or more of hydroxycyclohexane phenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone.

[0014] By adopting the above technical solution, the photoinitiator is a substance that can absorb light radiation energy, undergo chemical changes after excitation, and then produce an active intermediate with the ability to initiate polymerization. The present application obtains a photoinitiator suitable for UV ink adhesion by screening the photoinitiator, thereby improving the adhesion and weather resistance of the UV ink.

[0015] Preferably, a highly weather-resistant ink for reflective film printing comprises the following preparation steps: S1, one-step synthesis of active diluent: dissolving a certain amount of ammonium persulfate in deionized water, and mixing a certain amount of butyl acrylate and methyl methacrylate in proportion and stirring evenly, adding isobornyl acrylate with a monofunctional group to form an A emulsion, or adding tricyclodecane dimethanol diacrylate with a bifunctional group to form a B emulsion; S2, two-step synthesis of active diluent: adding a certain amount of polyvinyl alcohol and deionized water in a reaction kettle, heating to a certain temperature until the polyvinyl alcohol is dissolved in the water, adding a certain amount of A emulsion or B emulsion, and adding sodium dihydrogen phosphate and nonylphenol polyoxyethylene ether for emulsification, and controlling the temperature to maintain for a certain time; and cooling, adding a certain amount of tert-butyl hydroperoxide, continuing the reaction for a certain time, and adding a certain amount of ammonia solution, adjusting the pH within a certain range, and obtaining the active diluent by spray drying; S3, Synthesis of modified oligomers of polyurethane acrylate: After the air in the reactor is evacuated and nitrogen is introduced, a certain amount of dicyclohexylmethane diisocyanate and polytetrahydrofuran are added, and the mixture is mixed and heated for a certain time; then a certain amount of modifying reagent and catalyst di-n-butyltin dilaurate are added to carry out a chain extension reaction, and titration is carried out using di-n-butylamine titration method, and then a certain amount of acrylic acid-2-hydroxyethyl ester is added dropwise for titration under a certain temperature control until the isocyanate reaction is complete and polyurethane acrylate is obtained, which is stored in a light-proof environment; S4, synthesis of highly weather-resistant ink: the photoinitiator and the active diluent are mixed and dissolved in deionized water, and placed in a drying oven for drying and heating for a certain time, and the modified oligomer of polyurethane acrylate is added, mixed and stirred at a certain temperature for a certain time, and then pigment, thermal curing agent, and wetting agent are added in turn for mixing and stirring for a certain time until no dry powder appears in the ink, that is, the highly weather-resistant ink is completed.

[0016] By adopting the above technical solution,

[0017] Preferably, in the one-step synthesis step of the active diluent, 0.5-1.0 parts by weight of ammonium persulfate is dissolved in 8.0-12.0 parts by weight of deionized water, and 5.0-6.0 parts by weight of butyl acrylate and 2.0-3.0 parts by weight of methyl methacrylate are mixed and stirred evenly; and isobornyl acrylate with a monofunctional group or tricyclodecane dimethanol diacrylate with a difunctional group is added; wherein in emulsion A, isobornyl acrylate with a monofunctional group accounts for 1-5% of the total weight of emulsion A; and in emulsion B, tricyclodecane dimethanol diacrylate with a difunctional group accounts for 1-5% of the total weight of emulsion B.

[0018] Preferably, in the two-step synthesis step of the active diluent, 1.0-2.0 parts by weight of polyvinyl alcohol and 30.0-50.0 parts by weight of deionized water are added to a reaction kettle, the temperature is raised to 50°C-90°C until the polyvinyl alcohol is dissolved in the water, and 3.0-5.0 parts by weight of the A emulsion or B emulsion are added; sodium dihydrogen phosphate and nonylphenol polyoxyethylene ether are added for emulsification, and the temperature is controlled to be maintained at 70°C-90°C for 2-12 hours; and after cooling to 30°C-50°C, 0.5-1.5 parts by weight of tert-butyl hydroperoxide are added, the reaction is continued for 0.5-2.5 hours, and 10wt%-20wt% of ammonia solution is added at the same time, the pH is adjusted to 7-9, and finally the active diluent is obtained by spray drying for 0.5-1.5 hours;

[0019] Preferably, in the synthesis process of the modified oligomer of polyurethane acrylate, the weight ratio of dicyclohexylmethane diisocyanate, polytetrahydrofuran and modifying agent is 1-2:5-8:0.1-0.5.

[0020] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0021] 1. By adopting the above technical scheme, the present application makes improvements in the preparation process of the active diluent in the process of improving the weather resistance of UV ink, wherein the active diluent has good compatibility with the resin by using polyvinyl alcohol as a protective colloid as a shell, can be efficiently processed to ensure a high conversion rate of the reaction, and reduce the amount of residual monomers in the system.

[0022] 2. This application uses monofunctional isobornyl acrylate or difunctional tricyclodecane dimethanol diacrylate to form a seed emulsion, and prepares it into a core layer of active diluent. A suitable active diluent is selected according to the reflective film to further improve the weather resistance of the UV ink.

[0023] 3. The present application modifies polyurethane acrylate during the synthesis process by using a modification reagent; polydimethylsiloxane, polydiethylsiloxane or dimethylphenylsilane is used as a modification reagent, modified by silicone, and combined with polytetrahydrofuran as a polyether long carbon chain diol, which has high flexibility and thus helps in the synthesis of modified oligomers of polyurethane acrylate.

[0024] 4. In the present application, aziridine and acetylene glycol are added to UV ink as additives, wherein aziridine can improve the adhesion between UV ink and substrate; acetylene glycol helps leveling during the printing process, reduces bubbles, improves the adhesion durability and service life of UV ink, and thus improves its weather resistance. DETAILED DESCRIPTION

[0025] The present application provides a highly weather-resistant ink for printing on reflective film, which improves the weather resistance of UV ink and increases the life of UV ink during use while improving the adhesion of UV ink.

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] It should be noted that the terms "A", "B", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or server comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] raw material

[0029] Polyvinyl alcohol CAS number: 9002-89-5 Molecular weight: 44.053 Purity: 99.5%

[0030] Isobornyl acrylate CAS number: 5888-33-5 Molecular weight: 208.297 Purity: 99.5%

[0031] Tricyclodecane dimethanol diacrylate CAS number: 43048-08-4 Molecular weight: 332.434 Purity: 99.5%

[0032] Butyl acrylate CAS number: 141-32-2 Molecular weight: 128.169 Purity: 99.5%

[0033] Methyl methacrylate CAS number: 80-62-6 Molecular weight: 100.116 Purity: 99.5%

[0034] Dicyclohexylmethane diisocyanate CAS number: 5124-30-1 Molecular weight: 262.350 Purity: 99.5%

[0035] Polytetrahydrofuran CAS number: 25190-06-1 Molecular weight: 146.227 Purity: 99.5%

[0036] Polydimethylsiloxane CAS No.: 130169-63-0 Molecular weight: 460.82 Purity: 99.5%

[0037] Polydiethylsiloxane CAS No.: 63148-61-8 Molecular weight: 120.222 Purity: 99.5%

[0038] Dimethylphenylsilane CAS number: 766-77-8 Molecular weight: 136.266 Purity: 99.5%

[0039] Aziridine CAS number: 151-56-4 Molecular weight: 43.068 Purity: 99.5%

[0040] Alkynediol CAS number: 110-65-6 Molecular weight: 86.089 Purity: 99.5%

[0041] Example

[0042] Example 1

[0043] S1. One-step synthesis of active diluent: dissolve 1.0 kg of ammonium persulfate in 10.0 kg of deionized water, and mix and stir 5.0 kg of butyl acrylate and 2.0 kg of methyl methacrylate; and add 0.5 kg of monofunctional isobornyl acrylate to obtain emulsion A, and keep the monofunctional isobornyl acrylate accounting for 1-5% of the total weight of the emulsion A.

[0044] S2, two-step synthesis of active diluent: add 1.0 kg of polyvinyl alcohol and 30.0 kg of deionized water into a reaction kettle, heat to 80°C until the polyvinyl alcohol is dissolved in the water, and add 3.0 kg of A emulsion; add 0.5 kg of sodium dihydrogen phosphate and 0.8 kg of nonylphenol polyoxyethylene ether for emulsification, and control the temperature to maintain at 80°C for 8 hours; cool to 40°C, add 1.0 kg of tert-butyl hydroperoxide, continue to react for 2.0 hours, add 10 wt% ammonia solution, adjust the pH to 7-9, and finally spray dry for 1.0 hour to obtain the active diluent;

[0045] S3. Synthesis of modified oligomers of polyurethane acrylate: After the air in the reactor is evacuated and nitrogen is introduced, 10.0 kg of dicyclohexylmethane diisocyanate and 50.0 kg of polytetrahydrofuran are mixed and heated to 60° C. for 3 hours; then 1.0 kg of polydimethylsiloxane and 1.0 kg of 0.5 wt% catalyst di-n-butyltin dilaurate are added to carry out a chain extension reaction, and titration is performed using a di-n-butylamine titration method. Then, a certain amount of 2-hydroxyethyl acrylic acid is added dropwise for titration while controlling the temperature at 50° C.-60° C. until the isocyanate reaction is complete, thereby obtaining a modified oligomer of polyurethane acrylate, which is stored in a light-proof environment;

[0046] S4. Synthesis of highly weather-resistant ink: Mix 1.0 kg of 1 wt% hydroxycyclohexane phenone and 1.0 kg of active diluent and dissolve them in 2.0 kg of deionized water, place them in a drying oven and dry and heat for 30 minutes, add 3.0 kg of modified oligomer of polyurethane acrylate, mix and stir at 70°C for 3 hours, then add the required pigment, 0.1 kg of aziridine, and 0.2 kg of acetylene glycol in turn and mix and stir for 5 hours until there is no dry powder in the ink, that is, the highly weather-resistant ink is ready.

[0047] Example 2

[0048] The difference between Example 2 and Example 1 is that, during the one-step synthesis of the active diluent, 0.5 kg of seed emulsion formed by difunctional tricyclodecane dimethanol diacrylate is added to obtain emulsion B, and the seed emulsion formed by difunctional tricyclodecane dimethanol diacrylate accounts for 1-5% of the total weight of emulsion B.

[0049] Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 1 is that, in the process of synthesizing the active diluents of S1 and S2, polyvinyl alcohol is not used to form a protective colloid as the shell of the active diluent. Only in the step of synthesizing the S4 high weather resistance ink, a seed emulsion formed by monofunctional isobornyl acrylate, butyl acrylate and methyl methacrylate is added.

[0051] Comparative Example 2

[0052] The difference between Comparative Example 2 and Example 1 is that, in the active diluent synthesis process of S1 and S2, the main component of the active diluent is polyvinyl alcohol, and in the step of synthesizing the S4 high weather resistance ink, the seed emulsion formed by monofunctional isobornyl acrylate, butyl acrylate and methyl methacrylate is not added.

[0053] Comparative Example 3

[0054] The difference between Comparative Example 3 and Example 1 is that, during the synthesis of the active diluents of S1 and S2, the active diluent is synthesized by a one-step method, butyl acrylate and methyl methacrylate are mixed and stirred evenly; and isobornyl acrylate having a monofunctional group is added to obtain emulsion A; and polyvinyl alcohol is directly added to react directly with emulsion A, that is, polyvinyl alcohol does not form a protective colloid in the seed emulsion.

[0055] Performance testing

[0056] In order to further study the performance parameters of weather-resistant ink on reflective film, this application further carried out the following experimental verification.

[0057] 1. Ink performance testing

[0058] (1) Carry out ink viscosity test according to the method specified in the national standard GB / T 13217.4-2008.

[0059] (2) Carry out ink tinting strength test according to the method specified in the national standard GB / T 13217.6-2008.

[0060] (3) Carry out ink anti-adhesion test according to the method specified in the national standard GB / T 13217.8-2009.

[0061] 2. Reflective film performance test

[0062] The reflective film is UV printed using a UV printer, and after printing, the obtained UV printed reflective film product is subjected to an ink test.

[0063] (1) Refer to the national standard GB / T 6739-2006 "Paint Film Hardness Pencil Determination Method" as the test standard to test the surface hardness of the reflective film with a pencil. Place the sample on a horizontal table, and use the pencil to push the coating at a 45° angle, with a speed of about 1 cm / s and a pushing length of about 1 cm. The hardness of the pencil when it is scratched or abraded is the hardness of the plate.

[0064] (2) Perform artificial accelerated aging test according to the method specified in GB / T 16422.2. Set the blackboard temperature of the aging box to 65℃±3℃ and the relative humidity to 50%±5%. The irradiance between the spectral wavelength of 290nm~800nm ​​is 550W / ㎡, and the total irradiance between the spectral wavelength of 290nm~2450nm does not exceed 1000W / ㎡±100W / ㎡. The irradiance difference between any two points on the surface of the sample should not be greater than 10%. The test process uses continuous illumination and periodic water spraying. The water spraying cycle is 120min, of which 18min is water spraying and 102min is no water spraying. The test time is 600 hours, and the retroreflection coefficient of the reflective film is sampled and tested to obtain the following table.

[0065] (3) Test according to the method specified in the national standard GB / T 3512-2001. The air replacement frequency in the aging box is 4 times / hour, the temperature of the aging box is 50℃, the distance between samples is not less than 5mm, and the test time is 10 days and 100 days. Samples are taken and the transmittance and haze index are tested, and the following table is obtained.

[0066] Table 1. Performance test of inks of Examples 1-2 and Comparative Examples 1-3 Weatherability test experimental table

[0067]

[0068] Table 2. Performance test of reflective film of Examples 1-2 and Comparative Examples 1-3 Weather resistance performance test experimental table

[0069]

[0070] Through the combined analysis of Table 1 and Table 2, it can be obtained that from the data analysis of Comparative Example 1 and Example 1, it can be obtained that improvements are made in the preparation process of the active diluent, wherein the active diluent has good compatibility with the resin by using polyvinyl alcohol as a protective colloid as a shell, thereby increasing the viscosity of the ink and reducing adhesion. Printing the UV ink on the reflective film has better resistance to ultraviolet aging and thermal oxygen aging, thereby effectively improving its weather resistance. And from Comparative Example 2, it can be obtained that polyvinyl alcohol itself does not have the effect of improving the active diluent. In addition, it can be obtained from Comparative Example 3 that the two-step synthesis of the active diluent used in this application can make polyvinyl alcohol as a protective colloid as a shell, and at the same time, the monofunctional acrylate isobornyl ester forms a seed emulsion, thereby improving the performance of the UV ink.

[0071] In addition, from the analysis of Example 1 and Example 2, it can be obtained that the active diluent isobornyl acrylate, which can significantly reduce the internal stress of the coating and reduce the volume shrinkage of the coating, thereby significantly improving the adhesion and weather resistance of the radiation-cured coating without reducing its hardness and flexibility. The bifunctional diluent is tricyclodecane dimethanol diacrylate because it has good film toughness and weather resistance, but has large volume shrinkage, large internal stress, and is not easy to spread, so it is not suitable for reflective film with folding effect. It is necessary to select a suitable active diluent according to the reflective film and the cost of use to further improve the weather resistance of UV ink.

[0072] In addition, from the data analysis of Comparative Example 1 and Example 1, it can be obtained that improvements are made in the preparation process of the active diluent, wherein the active diluent has good compatibility with the resin by using polyvinyl alcohol as a protective colloid as a shell, and has better resistance to ultraviolet aging and thermal oxidation aging when printed on the reflective film from UV ink. In the accelerated aging test, after 600 hours of accelerated aging, the retroreflection coefficients of yellow, green and blue light are greatly reduced; at the same time, through the analysis of Comparative Example 2 and Comparative Example 3, after 600 hours of accelerated aging, the retroreflection coefficients of yellow, green and blue light are also greatly reduced in Comparative Example 2 and Comparative Example 3. It can also be obtained that polyvinyl alcohol itself does not have the effect of improving the active diluent; and the two-step synthesis of the active diluent is satisfied, so that polyvinyl alcohol is used as a protective colloid as a shell, and the monofunctional acrylate isobornyl ester forms a seed emulsion, which can improve the performance of UV ink. In summary, Example 1 is the best embodiment.

[0073] Example 3

[0074] The difference between Example 3 and Example 1 is that, in the process of synthesizing the polyurethane acrylate by using the modifying agent, polydiethylsiloxane is used as the modifying agent.

[0075] Example 4

[0076] The difference between Example 4 and Example 1 is that dimethylphenylsilane is used as a modifying agent during the synthesis of polyurethane acrylate.

[0077] Example 5

[0078] The difference between Example 5 and Example 1 is that, in the synthesis process of the highly weather-resistant ink, the photoinitiator used is 2-hydroxy-2-methyl-1-phenylpropanone.

[0079] Example 6

[0080] The difference between Example 6 and Example 1 is that, in the synthesis process of the highly weather-resistant ink, the photoinitiator used is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0081] Example 6

[0082] The difference between Example 7 and Example 1 is that, in the synthesis process of the highly weather-resistant ink, the photoinitiator used is 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone.

[0083] Performance testing

[0084] In order to further study the performance parameters of weather-resistant ink on reflective film, the present application further carried out the above-mentioned experimental verification, and sorted the data into the following two tables.

[0085] Table 3. Performance test of inks in Examples 1, 3-7 Weathering resistance test test table

[0086]

[0087]

[0088] Table 4. Performance test of reflective film of Examples 1, 3-7 Weathering performance test experimental table

[0089]

[0090] Through the combined analysis of Table 3 and Table 4, in the process of exploring weather resistance, as time changes, the hydrogen bonds of the hard segment of polyurethane acrylate decrease, the gap between molecules becomes larger, water molecules are more likely to enter, the degree of hydrolysis of urethane groups is greater, and the hydrophobic layer formed on the surface by the migration of silicone effectively reduces the entry of water molecules. The introduction of silicone makes the hard segment more dispersed, the hydrogen bonds of the hard segment are reduced, the phase separation degree of the soft and hard segments is lower, and the material has better flexibility. However, the introduction of low-polar silicone strengthens the phase separation degree due to its incompatibility, so its hardness and flexibility are worse. In the process of selecting the modifying agent, by using polydiethylsiloxane as the modifying agent, the obtained UV ink has better performance and can make the reflective film have more beneficial weather resistance.

[0091] In the process of selecting the photoinitiator, since the initiator molecule transitions from the ground state to the excited singlet state, it jumps to the excited triplet state through intersystem crossing; after the excited singlet state or triplet state undergoes unimolecular or bimolecular chemical action, active fragments that can initiate monomer polymerization are generated. Among them, these fragments include free radicals, cations, anions, etc. Free radical photoinitiators are used in this application. In the synthesis process of high weather-resistant ink, polymerization with the shell of polyvinyl alcohol can be reduced, and polymerization will not be initiated even if mixed with monomers and heated. Among them, in Example 7, the photoinitiator is 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, which has better weather resistance. However, considering the environmental issues, on the premise that Example 3 and Example 7 have similar weather resistance, Example 3 will be more friendly to the environment.

[0092] In addition, the present application also makes improvements on additives, wherein the additives include pigments, thermosetting agents, and wetting agents in addition to photoinitiators. Aziridine and acetylene glycol are added to UV ink as additives. In the prior art, aziridine as a thermosetting agent and acetylene glycol as a wetting agent directly act on the reflective film. In the present application, when both are added during the ink preparation process, aziridine can improve the adhesion between the UV ink and the reflective film; acetylene glycol helps leveling during the printing process, reduces bubbles, improves the adhesion durability and service life of the UV ink, and thus improves its weather resistance.

[0093] In addition, the pigment in the additive is a fine powder colored substance that is insoluble in water or solvents, but can be evenly dispersed in the base of paint and ink. In addition, by adding fillers to the pigment, in order to reduce the cost of paint and ink, but at the same time play an important role in the rheological properties and physical and mechanical properties of the pigment, the wear resistance and durability of the coating can be improved by increasing the thickness of the coating. Specifically, the fillers include inorganic substances such as calcium carbonate, barium sulfate, aluminum hydroxide, kaolin, etc., and their refractive index is close to that of polyurethane acrylate oligomers and active diluents, which makes the pigment have better tinting power.

[0094] It should be noted that the above-mentioned sequence of the embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0095] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0096] This specification is merely an exemplary description of the present application and is deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, those skilled in the art may make various modifications and variations to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalents, the present application is intended to include these modifications and variations.

Claims

1. A highly weather-resistant ink for printing reflective film, characterized in that: The raw materials of the ink include modified oligomer of polyurethane acrylate, active diluent, additive and water; the active diluent has a two-layer structure, including a shell layer and a core layer; The shell layer is formed by using polyvinyl alcohol as a protective colloid; the raw material of the core layer includes a seed emulsion formed by isobornyl acrylate having a monofunctional group and a seed emulsion formed by tricyclodecane dimethanol diacrylate having a bifunctional group; Each of the seed emulsions also includes butyl acrylate and methyl methacrylate.

2. The highly weather-resistant ink for printing on reflective film according to claim 1, characterized in that: The raw materials of the modified oligomer of polyurethane acrylate include polyurethane acrylate and a modification agent for polyurethane acrylate; the raw materials of the polyurethane acrylate include dicyclohexylmethane diisocyanate and polytetrahydrofuran.

3. The highly weather-resistant ink for printing on reflective film according to claim 2, characterized in that: The modifying agent includes one or more of polydimethylsiloxane, polydiethylsiloxane, and dimethylphenylsilane.

4. The highly weather-resistant ink for printing on reflective film according to claim 1, characterized in that: The additives include pigment, thermal curing agent, wetting agent and photoinitiator; the thermal curing agent is aziridine, and the wetting agent is acetylene glycol.

5. The highly weather-resistant ink for printing on reflective film according to claim 4, characterized in that: The photoinitiator includes one or more of hydroxycyclohexane phenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone.

6. The highly weather-resistant ink for printing reflective film according to any one of claims 1 to 5, characterized in that: The method comprises the following preparation steps: S1. One-step synthesis of active diluent: dissolving a certain amount of ammonium persulfate in deionized water, and mixing a certain amount of butyl acrylate and methyl methacrylate in proportion and stirring evenly, adding isobornyl acrylate having a monofunctional group to form emulsion A, or adding tricyclodecane dimethanol diacrylate having a difunctional group to form emulsion B; S2, two-step synthesis of active diluent: adding a certain amount of polyvinyl alcohol and deionized water into a reaction kettle, heating to a certain temperature until the polyvinyl alcohol is dissolved in the water, adding a certain amount of A emulsion or B emulsion, adding sodium dihydrogen phosphate and nonylphenol polyoxyethylene ether for emulsification, and controlling the temperature to maintain for a certain time; cooling, adding a certain amount of tert-butyl hydroperoxide, continuing the reaction for a certain time, adding a certain amount of ammonia solution, adjusting the pH within a certain range, and spray drying to obtain the active diluent; S3. Synthesis of modified oligomers of polyurethane acrylate: After the air in the reaction kettle is evacuated and nitrogen is introduced, a certain amount of dicyclohexylmethane diisocyanate and polytetrahydrofuran are added, and the mixture is mixed and heated for a certain period of time; then a certain amount of modifying reagent and catalyst di-n-butyltin dilaurate are added to carry out a chain extension reaction, and titration is performed using a di-n-butylamine titration method. Then, under a certain temperature, a certain amount of 2-hydroxyethyl acrylate is added dropwise for titration until the isocyanate reaction is complete and polyurethane acrylate is obtained, which is then stored in a light-proof environment; S4. Synthesis of highly weather-resistant ink: The photoinitiator and the active diluent are mixed and dissolved in deionized water, and placed in a drying oven for drying and heating for a certain period of time, and the modified oligomer of polyurethane acrylate is added, and mixed and stirred at a certain temperature for a certain period of time, and then the pigment, thermal curing agent, and wetting agent are added in turn and mixed and stirred for a certain period of time until no dry powder appears in the ink, that is, the production of highly weather-resistant ink is completed.

7. The highly weather-resistant ink for printing on reflective film according to claim 6, characterized in that: In the one-step synthesis step of the active diluent, 0.5-1.0 parts by weight of ammonium persulfate is dissolved in 8.0-12.0 parts by weight of deionized water, and 5.0-6.0 parts by weight of butyl acrylate and 2.0-3.0 parts by weight of methyl methacrylate are mixed and stirred evenly; and isobornyl acrylate with a monofunctional group or tricyclodecane dimethanol diacrylate with a difunctional group is added; wherein in the A emulsion, the isobornyl acrylate with a monofunctional group accounts for 1-5% of the total weight of the A emulsion; and in the B emulsion, the tricyclodecane dimethanol diacrylate with a difunctional group accounts for 1-5% of the total weight of the B emulsion.

8. The highly weather-resistant ink for printing on reflective film according to claim 6, characterized in that: In the two-step synthesis step of the active diluent, 1.0-2.0 parts by weight of polyvinyl alcohol and 30.0-50.0 parts by weight of deionized water are added to a reaction kettle, the temperature is raised to 50°C-90°C until the polyvinyl alcohol is dissolved in the water, and 3.0-5.0 parts by weight of the A emulsion or the B emulsion are added; sodium dihydrogen phosphate and nonylphenol polyoxyethylene ether are added for emulsification, and the temperature is controlled to be maintained at 70°C-90°C for 2-12 hours; and after cooling to 30°C-50°C, 0.5-1.5 parts by weight of tert-butyl hydroperoxide are added, the reaction is continued for 0.5-2.5 hours, and 10wt%-20wt% of ammonia solution is added at the same time, the pH is adjusted to be in the range of 7-9, and finally the active diluent is obtained by spray drying for 0.5-1.5 hours.

9. The highly weather-resistant ink for printing on reflective film according to claim 6, characterized in that: In the synthesis process of the modified oligomer of polyurethane acrylate, the weight ratio of dicyclohexylmethane diisocyanate, polytetrahydrofuran and the modifying agent is 1-2:5-8:0.1-0.5.

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