Yellowing-resistant offset printing LED tin printing ink and preparation method thereof

Abstract

The invention provides yellowing-resistant offset printing LED (light-emitting diode) tin printing ink. The yellowing-resistant offset printing LED tin printing ink is prepared from an acrylate active monomer, silane coupling agent modified liquid rubber, a silane coupling agent modified acrylate monomer, a photoinitiator, a pigment, a dispersing agent, a flatting agent and a defoaming agent. The invention also provides a preparation method of the anti-yellowing offset printing LED tin printing ink. According to the yellowing-resistant offset printing LED tin printing ink provided by the invention, deep curing can be realized through an alkoxy hydrolytic condensation curing mode of the LED and the silane coupling agent. The silane coupling agent modified liquid rubber and the silane coupling agent modified acrylate monomer are introduced, so that the yellowing resistance, the flexibility, the plasticity, the cohesive strength and the adhesive force of an ink film are improved, and the tin printing ink has the characteristics of yellowing resistance and good deep drawing processing performance.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry and relates to the field of coatings and inks, and in particular to a yellowing-resistant offset LED tinplate ink and a preparation method thereof. Background Art

[0002] With the booming packaging industry, iron packaging or metal packaging is being used more and more due to its unique properties. The demand and application of corresponding tinplate inks are also very extensive. As people's requirements for packaging quality continue to increase, the performance requirements for tinplate inks are also getting higher and higher.

[0003] As people pay more attention to tinplate ink, more and more professions related to tinplate ink are also emerging. The invention patent with application number 201811553003.2 discloses an LED light-cured tinplate ink and its preparation method. The ink composition is in weight ratio (parts): 30-60 parts of prepolymer, 6-30 parts of active monomer diluent, 10-12 parts of photoinitiator, 20-40 parts of pigment, and 2-4 parts of additive. Through the design of the ink components, a mixture of high-functionality polyurethane acrylate, special modified acrylate, modified polyester acrylate and amine-modified polyether acrylate is selected as the main resin to provide the ink with a skeleton component on the surface of the ink layer. It dries quickly under LED light source, the surface hardness of the ink layer is high, it is scratch-resistant, and has good adhesion. For example, the invention patent with application number 202210538127.3 provides an offset LED tin printing ink capable of deep drawing and a preparation method thereof. In parts by weight, the offset LED tin printing ink includes the following components: 50-70 parts of alicyclic side chain modified polyurethane acrylate, 5-10 parts of epoxy soybean oil modified acrylate, 10-30 parts of active monomers, 20-30 parts of pigments, 10-30 parts of fillers, 3-8 parts of photoinitiators, 0.5-5 parts of leveling agents, 0.1-0.5 parts of defoaming agents, and 0.5-1 parts of dispersants.

[0004] After drying, tinplate ink generally involves stamping or re-plasticization, which places higher requirements on the toughness and adhesion of tinplate ink. In order to improve toughness, adhesion and deep drawing processability, the above patents all use polyurethane modified components. Due to their molecular structure characteristics, polyurethane substances have certain flexibility and good adhesion. However, due to the core molecular structure of polyurethane, the carbamate structure, it has poor yellowing resistance, heat resistance, hydrolysis resistance and other properties, which will bring other negative effects to the ink during actual use. For example, during the LED curing process or the thermal oxidation aging process, the coating containing the carbamate structure is prone to yellowing. Summary of the invention

[0005] In view of the above technical problems in the prior art, the present invention provides a yellowing-resistant offset LED tin printing ink and a preparation method thereof. The yellowing-resistant offset LED tin printing ink and the preparation method thereof are intended to solve the technical problem in the prior art that the offset LED tin printing ink is prone to yellowing during processing.

[0006] The present invention provides a yellowing-resistant offset LED tin printing ink, which is prepared from the following raw materials in parts by weight: 40-80 parts of acrylic acid ester active monomer; 10-30 parts of liquid rubber modified by silane coupling agent; 10-30 parts of silane coupling agent modified acrylate monomer; 8-10 parts of photoinitiator; Pigment 20-40 parts; 1-2 parts of dispersant; Leveling agent 0.5-2 parts; Defoaming agent 0.1-0.5 parts.

[0007] Furthermore, the acrylic ester active monomer is any one of ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, or a mixture of two or more thereof.

[0008] Furthermore, the silane coupling agent modified liquid rubber has a molecular weight in the range of 1000-50000 and contains more than two silane coupling agent grafted structures at both ends of the molecular chain or at the middle branch, and its rubber body is any one of polyisobutylene liquid rubber, styrene butadiene copolymer liquid rubber, polyisoprene liquid rubber, and polybutadiene liquid rubber, or a mixture of two or more thereof.

[0009] Furthermore, the silane coupling agent is any one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane, or a mixture of two or more thereof.

[0010] Specifically, the polybutadiene liquid rubber is selected from any one of Evonik's POLYVEST110 and POLYVEST130; the polyisoprene liquid rubber is selected from Rock Oil's ROCEOIL LIR50; the polyisobutylene liquid rubber is selected from Shandong Hongrui's HRDF350; the styrene butadiene copolymer liquid rubber is selected from Lufei Technology's LSBR-4.

[0011] Furthermore, the silane-grafted liquid rubber is prepared by the following method: 100 parts by weight of liquid rubber, 0.5-3 parts by weight of silane coupling agent, and 0.05-0.15 parts by weight of peroxide are weighed, and a twin-screw extrusion reaction technology is used for grafting reaction. The screw temperature is set as follows: 30°C in zones 1-3, 60°C in zone 4, 80°C in zone 5, 100°C in zone 6, 140°C in zone 7, 180°C in zone 8, 190°C in zones 9-12, and 150°C in zone 13. The die temperature is 120°C. After the materials come out, they are packaged in sealable stainless steel barrels for standby use. The peroxide is tert-amyl peroxy (2-ethylhexyl) carbonate (Arkema's peroxide product LuperoxTAEC).

[0012] Furthermore, the grafting rate of the silane coupling agent modified liquid rubber is evaluated by infrared absorption. When the grafting rate reaches 50% or more, it is considered to have reached the expected index. The remaining part of the silane coupling agent is mixed into the next step as a free added component.

[0013] Furthermore, the silane coupling agent-modified acrylate monomer has an acrylate structure at one end and a silane coupling agent grafted structure at the other end.

[0014] Specifically, the preparation method of the silane coupling agent-modified acrylate monomer comprises the following steps: 1) Add the difunctional acrylate monomer into a reaction kettle equipped with a thermometer and a dropping funnel; 2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; 3) Start stirring and heat to 70-80°C at the same time, and evenly add the solution of step 2) to the bifunctional acrylate monomer and react for 1-3 hours to obtain silane coupling agent modified acrylate.

[0015] Furthermore, the molar ratio of the bifunctional acrylate monomer to the silane coupling agent is 1.2-1.5:1, the thermal initiator accounts for 1‰-3‰ of the total mass of the reaction raw materials, and the silane coupling agent is any one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane, or a mixture of two or more thereof; the thermal initiator is any one of azobisisobutyronitrile or benzoyl peroxide.

[0016] Furthermore, the bifunctional acrylate monomer is one of diethylene glycol dimethacrylate, dipropylene glycol diacrylate, 2-methyl-1,3-propanediol diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, and polyethylene glycol (400) dimethacrylate, or a mixture of any of them.

[0017] Furthermore, the photoinitiator is any one of 2-isopropylthioxanthone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone and 2,4-diethylthioxanthone, or a mixture of two or more thereof.

[0018] Furthermore, the pigment is rutile titanium dioxide.

[0019] Furthermore, the dispersant is selected from any one of DISPERBYK-111 of BYK, DISPERBYK-2013 of BYK, and DISPERBYK-2030 of BYK, or a mixture of two or more thereof.

[0020] Furthermore, the leveling agent is BYK361N.

[0021] Furthermore, the defoaming agent is selected from any one of BYK1797 and BYK055, or a mixture of two or more thereof.

[0022] The present invention also provides a method for preparing yellowing-resistant offset LED tinplate ink, comprising the following steps: Weigh each reaction raw material according to weight; First, put the pigment, dispersant and acrylic ester active monomer into a sand mill and grind them in a sealed state for 30-40 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, filter and obtain the pigment paste. Put the liquid rubber modified by silane coupling agent, silane coupling agent modified acrylate monomer, photoinitiator, leveling agent, defoamer and ground color paste into a sealed planetary mixer for dispersion and stirring. After stirring evenly, filter the material and seal it for storage to obtain the yellowing-resistant offset LED tinplate ink.

[0023] In order to improve the processing performance of tinplate ink such as deep drawing or molding, improve the flexibility and adhesion of LED tinplate ink, and at the same time improve the yellowing resistance of tinplate ink, the present invention provides a tinplate ink with good adhesion on metal surfaces, flexibility, good yellowing resistance, heat resistance, water resistance and other physical properties, which can be deep drawn.

[0024] The liquid rubber modified by the silane coupling agent used in the present invention has flexibility, and the glass transition temperature of the liquid rubber is generally below zero. It can play the role of a toughening agent in the system during the deep drawing process. At the same time, the structure grafted with the silane coupling agent can undergo hydrolysis and polycondensation reaction of the siloxane structure after printing and contact with a small amount of moisture to form a cross-linked structure. At the same time, the silane coupling agent can also form a covalent bond with the metal surface to enhance the adhesion between the ink and the metal surface.

[0025] The silane coupling agent-modified acrylate monomer used in the present invention can react with the silane coupling agent-modified liquid rubber to form a linking bridge between the liquid rubber and the acrylate cross-linking resin to link the liquid rubber and the acrylate resin, thereby improving the overall strength of the ink binder resin. At the same time, the modified silane coupling agent structure also has the effect of improving the adhesion to the metal.

[0026] Since the invention does not contain the carbamate structure of polyurethane, the ink has good yellowing resistance after printing and is also better in water resistance than the product containing carbamate.

[0027] Compared with the prior art, the technical effect of the present invention is positive and obvious. The offset LED tin printing ink capable of deep drawing provided by the present invention can achieve deep curing by the alkoxy hydrolysis condensation curing of LED and silane coupling agent. The introduction of liquid rubber component, since the glass transition temperature of rubber is dozens of degrees below zero, can allow a certain displacement of the molecular chain during the deep drawing process, and eliminate the internal stress of the processing process through the conformational change of the molecular chain. At the same time, the liquid rubber modified by the silane coupling agent and the acrylate monomer modified by the silane coupling agent are used in combination, and the alkoxy hydrolysis condensation effectively improves the overall strength of the ink after curing. At the same time, the silane coupling agent can also form a chemical bond with the metal surface, which is beneficial to improve the adhesion. DETAILED DESCRIPTION

[0028] Example 1

[0029] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and 3-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent) was used to graft and modify polyisobutylene liquid rubber (HRDF350 of Shandong Hongrui). The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 0.5kg of silane coupling agent, and 0.05kg of Luperox TAEC, a peroxide product of Arkema, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: 3-(methacryloyloxy)propyltriethoxysilane (silane coupling agent) modified bifunctional acrylate monomer diethylene glycol dimethacrylate: bifunctional acrylate monomer 1.2mol; silane coupling agent 3-(methacryloyloxy)propyltriethoxysilane 1mol, thermal initiator azobisisobutyronitrile accounts for 1‰ of the total mass of the reaction raw materials; (1) Add difunctional acrylate monomer (diethylene glycol dimethacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel; (2) dissolving the thermal initiator, azobisisobutyronitrile, in the vinyl silane coupling agent 3-(methacryloyloxy)propyltriethoxysilane and placing the mixture in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 20 kg of rutile titanium dioxide pigment, 1 kg of dispersant (DISPERBYK-111 of BYK Chemical), and 40 kg of ethoxylated trimethylolpropane triacrylate monomer of acrylic acid ester are put into a sand mill, sealed and ground for 30 minutes, and when the pigment fineness reaches the required particle size of 1-6 μm, the pigment paste is filtered to obtain the pigment paste. The ground paste, 10 kg of liquid rubber modified by silane coupling agent, 10 kg of acrylate monomer modified by silane coupling agent, 8 kg of photoinitiator 2-isopropylthioxanthone, 0.5 kg of leveling agent (BYK361N), and 0.1 kg of defoamer (BYK1797) are put into a sealed and stirred planetary mixer, and after being evenly stirred, the material is filtered out and sealed and stored to obtain the LED iron printing ink.

[0030] Example 2

[0031] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and vinyl triethoxysilane (silane coupling agent) was used to graft-modify styrene butadiene copolymer liquid rubber (LSBR-4 type of Lufei Technology). The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 3kg of silane coupling agent, and 0.15kg of peroxide TAEC, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: vinyl trimethoxysilane (silane coupling agent) modified dipropylene glycol diacrylate: difunctional acrylate monomer 1.5 mol; silane coupling agent 1 mol, thermal initiator benzoyl peroxide accounts for 3‰ of the total mass; (1) Add difunctional acrylate monomer (dipropylene glycol diacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel; (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 40 kg of rutile titanium dioxide pigment, 2 kg of dispersant (DISPERBYK-2013 of BYK Chemical), and 80 kg of propoxylated glycerol triacrylate monomer of acrylic acid ester are put into a sand mill, sealed and ground for 40 minutes, and when the pigment fineness reaches the required particle size of 1-6 μm, the pigment paste is filtered to obtain the pigment paste. The ground paste, 30 kg of liquid rubber modified by silane coupling agent, 30 kg of acrylate monomer modified by silane coupling agent, 10 kg of photoinitiator diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, 2 kg of leveling agent (BYK361N), and 0.5 kg of defoamer (BYK055) are put into a sealed and stirred planetary mixer, and after being evenly stirred, the material is filtered and sealed to obtain the LED iron printing ink.

[0032] Example 3

[0033] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and 3-methacryloxypropyl triethoxysilane (silane coupling agent) was used to graft-modify polybutadiene liquid rubber Evonik's POLYVEST110. The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 2kg of silane coupling agent, and 0.1kg of peroxide TAEC, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: vinyl triethoxysilane (silane coupling agent) modified acrylate monomer 2-methyl-1,3-propanediol diacrylate: bifunctional acrylate monomer 1.3 mol, silane coupling agent 1 mol, thermal initiator azobisisobutyronitrile accounts for 2‰ of the total mass; (1) Adding a difunctional acrylate monomer (2-methyl-1,3-propanediol diacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel; (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 30 kg of rutile titanium dioxide pigment, 1.5 kg of dispersant (DISPERBYK-2030 of BYK Chemical), and 60 kg of acrylate monomer pentaerythritol triacrylate are put into a sand mill, sealed and ground for 35 minutes, and when the pigment fineness reaches the required particle size of 1-6 μm, the pigment paste is filtered to obtain the pigment paste. The ground paste, 20 kg of liquid rubber modified by silane coupling agent, 20 kg of acrylate monomer modified by silane coupling agent, 9 kg of photoinitiator 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone, 1 kg of leveling agent (BYK361N), and 0.3 kg of defoamer (BYK1797) are put into a sealed and stirred planetary mixer, and after being evenly stirred, the material is filtered and sealed to obtain the LED iron printing ink.

[0034] Example 4

[0035] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and vinyl trimethoxysilane (silane coupling agent) was used to graft and modify polyisoprene liquid rubber ROCEOIL LIR50 of Rock Oil. The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 1.5kg of silane coupling agent, and 0.08kg of peroxide TAEC, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: vinyl triethoxysilane (silane coupling agent) modified acrylate monomer 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate: bifunctional acrylate monomer 1.4 mol, silane coupling agent 1 mol, thermal initiator benzoyl peroxide accounts for 1.7‰ of the total mass; (1) Adding a difunctional acrylate monomer (1,3-butanediol diacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel; (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 35 kg of rutile titanium dioxide pigment, 1.6 kg of dispersant (DISPERBYK-2030 of BYK Chemical), and 50 kg of acrylate monomer polyethylene glycol diacrylate were put into a sand mill and sealed for grinding for 38 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, the pigment paste was filtered to obtain the pigment paste. The ground paste, 25 kg of liquid rubber modified by silane coupling agent, 15 kg of acrylate monomer modified by silane coupling agent, 10 kg of photoinitiator 2,4-diethylthioxanthone, 1.4 kg of leveling agent (BYK361N), and 0.2 kg of defoamer (BYK055) were put into a sealed planetary mixer, and after stirring evenly, the material was filtered and sealed to obtain the LED iron printing ink.

[0036] Example 5

[0037] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and vinyl triethoxysilane (silane coupling agent) was used to graft and modify polybutadiene liquid rubber (POLYVEST130 of Evonik). The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 2.5kg of silane coupling agent, and 0.07kg of peroxide TAEC, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: vinyl trimethoxysilane (silane coupling agent) modified acrylate monomer 1,3-butanediol dimethacrylate: bifunctional acrylate monomer 1.5 mol, silane coupling agent 1 mol, thermal initiator azobisisobutyronitrile accounts for 1.6‰ of the total mass; (1) Adding a difunctional acrylate monomer (1,3-butanediol dimethacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel; (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 40 kg of rutile titanium dioxide pigment, 1.2 kg of dispersant (DISPERBYK-2013 of BYK Chemical), and 75 kg of acrylate monomer polyethylene glycol dimethacrylate are put into a sand mill, sealed and ground for 40 minutes, and when the pigment fineness reaches the required particle size of 1-6 μm, the pigment paste is filtered to obtain the pigment paste. The ground paste, 26 kg of liquid rubber modified by silane coupling agent, 18 kg of acrylate monomer modified by silane coupling agent, 9 kg of photoinitiator 2-isopropylthioxanthone, 1.2 kg of leveling agent (BYK361N), and 0.2 kg of defoamer (BYK1797) are put into a sealed and stirred planetary mixer, and after being evenly stirred, the material is filtered out and sealed and stored to obtain the LED iron printing ink.

[0038] Example 6

[0039] Silane coupling agent modified liquid rubber: twin-screw extrusion reaction technology was used for grafting reaction, and 3-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent) was used to graft and modify polybutadiene liquid rubber. The screw temperature was set as follows: 1-3 zone temperature 30°C, 4 zone 60°C, 5 zone 80°C, 6 zone 100°C, 7 zone 140°C, 8 zone 180°C, 9-12 zone 190°C, 13 zone 150°C, die head temperature 120°C, according to 100kg of liquid rubber, 0.8kg of silane coupling agent, and 0.11kg of peroxide TAEC, to obtain silane coupling agent grafted modified liquid rubber; Silane coupling agent modified acrylate monomer: 3-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent) modified acrylate monomer neopentyl glycol diacrylate and 1,6 hexanediol dimethacrylate in equal proportion: bifunctional acrylate monomer 1.5 mol; silane coupling agent 1 mol, thermal initiator azobisisobutyronitrile accounts for 2‰ of the total mass; (1) Adding difunctional acrylate monomer neopentyl glycol diacrylate into a reaction kettle equipped with a thermometer and a dropping funnel; (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; (3) Start stirring and heat to 70-80° C., and uniformly add the solution of step (2) dropwise to the bifunctional acrylate monomer to react for 1-3 hours to obtain a silane coupling agent-modified acrylate monomer; Ink preparation: First, 40 kg of rutile titanium dioxide pigment, 1.3 kg of dispersant (DISPERBYK-111 of BYK Chemical), and 40 kg of ethoxylated trimethylolpropane triacrylate and 40 kg of pentaerythritol triacrylate of acrylic ester monomers were put into a sand mill and sealed for grinding for 40 minutes. When the pigment fineness reached the required particle size of 1-6 μm, the pigment paste was filtered to obtain the pigment paste. The ground paste, 20 kg of liquid rubber modified by silane coupling agent, 10 kg of acrylate monomer modified by silane coupling agent, 10 kg of photoinitiator 2,4-diethylthioxanthone, 1.7 kg of leveling agent (BYK361N), and 0.2 kg of defoamer (BYK055) were put into a sealed planetary mixer, and after stirring evenly, the material was filtered out and sealed for storage to obtain the LED iron printing ink.

[0040] Comparative Example 1 First, 40 kg of rutile titanium dioxide pigment; Dispersant 1.5 kg (DISPERBYK-2013 from BYK Chemical); Acrylate monomer ethoxylated trimethylolpropane triacrylate 40kg; Pentaerythritol triacrylate 110kg; Photoinitiator 2,4-diethylthioxanthone 10kg; Leveling agent (BYK361N) 1.7kg; Defoaming agent (BYK1797) 0.3 kg; The mixture is put into a sand mill and ground in a sealed state for 40 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, the mixture is filtered out and sealed for storage to obtain the LED tinplate ink.

[0041] Comparative Example 2 First, 40 kg of rutile titanium dioxide pigment; Dispersant (DISPERBYK-2013 from BYK) 1.2 kg; Acrylate monomer polyethylene glycol dimethacrylate 119kg; Photoinitiator 2-isopropylthioxanthone 9kg; Leveling agent (BYK361N) 1.2kg; Defoaming agent (BYK1797) 0.2 kg; The mixture is put into a sand mill and ground in a sealed state for 40 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, the mixture is filtered out and sealed for storage to obtain the LED tinplate ink.

[0042] Comparative Example 3 70 kg of polyurethane acrylate modified with alicyclic side chains; Epoxidized soybean oil modified acrylate 10kg; 1,6-Hexanediol diacrylate 10kg; Ethoxylated pentaerythritol tetraacrylate 10kg (Guojing Chemical); Rutile titanium dioxide 30kg; 10kg talcum powder; Diphenyl-(2,4,6-trimethylbenzoyl)phosphine 9kg; Leveling agent (BYK361N) 0.5kg; Defoaming agent (BYK1797) 0.3 kg; Dispersant (DISPERBYK-2030 from BYK) 0.7 kg; The mixture is put into a sand mill and ground in a sealed state for 40 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, the mixture is filtered out and sealed for storage to obtain the LED tinplate ink.

[0043] Comparative Example 4 80 kg of polyurethane acrylate modified with alicyclic side chains; Epoxidized soybean oil modified acrylate 10kg; 1,6-Hexanediol diacrylate (Changxing Chemical) 10kg; Ethoxylated pentaerythritol tetraacrylate (Guojing Chemical) 10kg; Rutile titanium dioxide 30kg; 10kg talcum powder; Photoinitiator 2-isopropylthioxanthone 9kg; Leveling agent (BYK361N) 0.5kg; Defoaming agent (BYK1797) 0.4 kg; Dispersant (DISPERBYK-111 from BYK) 0.5 kg; The mixture is put into a sand mill and ground in a sealed state for 40 minutes. When the pigment fineness reaches the required particle size of 1-6 μm, the mixture is filtered out and sealed for storage to obtain the LED tinplate ink.

[0044] The performance of the tinplate inks provided in the above embodiments and comparative examples was compared, and the test method was as follows: Under the same conditions, the ink is printed on tinplate of the same specifications; Yellowing resistance: The printed test samples were subjected to UV aging for 100 hours under the same conditions, and the increment of the yellow index (YI) before and after aging was compared. The larger the increment, the poorer the yellowing resistance. Flexibility: Fold in half at 180° to observe the bursting condition; The adhesion of the coating film is measured according to GB / T9286-1998, ISO2409:1992 method; Impact resistance: Drop hammer impact tester; The test data of each embodiment and comparative example are shown in Table 1:

[0045] By comparing the yellowing performance of the inks in the examples under the same conditions, the yellowing index of the inks in the examples after UV aging is significantly lower, indicating good yellowing resistance. By the folding test, the examples did not crack. The impact resistance was above 70. Comprehensively evaluated, the examples were excellent in terms of yellowing resistance, adhesion and impact resistance.

[0046] The reasons for the difference in composition are analyzed as follows: (1) Introducing liquid rubber modified with silane coupling agent and acrylate monomer modified with silane coupling agent. Since these two materials do not contain nitrogen atoms in their molecular structure, they are mainly carbon-carbon bonds, carbon-hydrogen bonds, silicon-oxygen bonds, etc., and are not easy to form chromophores, and have good yellowing resistance; (2) Introducing a liquid rubber component modified by a silane coupling agent. Since there are many flexible molecular segments in the rubber molecular structure that can undergo a certain displacement, the molecular chain can be allowed to have a certain displacement during the deep drawing process. The conformational change of the molecular chain can also eliminate part of the internal stress of the processing process. The introduction of the rubber structure improves the flexibility and plasticity of the material. (3) The introduction of silane coupling agent grafting structure can form a cross-linked structure through hydrolysis and condensation. On the one hand, it can improve the bonding strength between rubber phases and between rubber phase and acrylate phase, thereby improving the overall cohesive strength of the ink film, making it less likely to be damaged during deep drawing. On the other hand, the silane coupling agent at the metal interface can also form a chemical bond with the metal surface, enhancing the adhesion between the ink film and the metal, thereby enhancing the adhesion of the ink film to the substrate; In Examples 1-6, the yellowing resistance, flexibility, plasticity, material cohesive strength, adhesion and other properties of the ink film are improved because of the use of liquid rubber modified by silane coupling agent and acrylate monomer modified by silane coupling agent.

[0047] Comparative Examples 1 and 2 do not add toughening components. Although the yellowing resistance is good, due to poor toughness and adhesion, the ink film bursts during the bending comparison test.

[0048] Comparative Examples 3 and 4 add a polyurethane component to improve the flexibility of the ink film, making the ink film have better impact resistance and better deep drawing processing performance. However, due to the molecular structure of carbamate, the nitrogen atoms therein are easy to form chromophores, which significantly deteriorates the yellowing resistance of the overall ink film.

Claims

1. A yellowing-resistant offset LED tinplate ink, characterized in that It is prepared from the following raw materials in parts by weight: 40-80 parts of acrylic acid ester active monomer; 10-30 parts of liquid rubber modified by silane coupling agent; 10-30 parts of silane coupling agent modified acrylate monomer; 8-10 parts of photoinitiator; Pigment 20-40 parts; 1-2 parts of dispersant; Leveling agent 0.5-2 parts; Defoaming agent 0.1-0.5 parts.

2. The yellowing-resistant offset LED tin printing ink according to claim 1, characterized in that: The acrylic ester active monomer is any one of ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, or a mixture of two or more thereof.

3. The yellowing-resistant offset LED tin printing ink according to claim 1, characterized in that: The silane coupling agent modified liquid rubber has a molecular weight in the range of 1000-50000 and contains more than two silane coupling agent grafted structures at both ends of the molecular chain or at the middle branch. The rubber body is any one of polyisobutylene liquid rubber, styrene butadiene copolymer liquid rubber, polyisoprene liquid rubber, and polybutadiene liquid rubber, or a mixture of two or more thereof. The silane coupling agent is any one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane, or a mixture of two or more thereof.

4. The yellowing-resistant offset LED tin printing ink according to claim 3, characterized in that: The silane coupling agent modified liquid rubber is prepared by the following method: 100 parts by weight of liquid rubber, 0.5-3 parts by weight of silane coupling agent, and 0.05-0.15 parts by weight of peroxide are weighed, and a twin-screw extrusion reaction technology is used for grafting reaction. The screw temperature is set as follows: 30°C in zones 1-3, 60°C in zone 4, 80°C in zone 5, 100°C in zone 6, 140°C in zone 7, 180°C in zone 8, 190°C in zones 9-12, and 150°C in zone 13. The die temperature is 120°C. The peroxide is tert-amyl peroxy (2-ethylhexyl) carbonate.

5. The yellowing-resistant offset LED tin printing ink according to claim 1, characterized in that: The silane coupling agent modified acrylate monomer has an acrylate structure at one end and a silane coupling agent grafted structure at the other end.

6. The yellowing-resistant offset LED tin printing ink according to claim 5, characterized in that: The preparation method of the silane coupling agent-modified acrylate monomer comprises the following steps: 1) Add the difunctional acrylate monomer into a reaction kettle equipped with a thermometer and a dropping funnel; 2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in a dropping funnel; 3) Start stirring and heat to 70-80°C at the same time, and evenly add the solution in step 2) to the bifunctional acrylate monomer and react for 1-3 hours to obtain a silane coupling agent modified acrylate monomer.

7. The yellowing-resistant offset LED tin printing ink according to claim 6, characterized in that: The molar ratio of the bifunctional acrylate monomer to the silane coupling agent is 1.2-1.5:1, the thermal initiator accounts for 1‰-3‰ of the total mass of the reaction raw materials, the silane coupling agent is one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane, or a mixture of two or more thereof, and the thermal initiator is one of azobisisobutyronitrile or benzoyl peroxide.

8. The yellowing-resistant offset LED tin printing ink according to claim 6, characterized in that: The bifunctional acrylate monomer is one of diethylene glycol dimethacrylate, dipropylene glycol diacrylate, 2-methyl-1,3-propanediol diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, and polyethylene glycol (400) dimethacrylate, or a mixture of any of the above.

9. The yellowing-resistant offset LED tin printing ink according to claim 2, characterized in that: The photoinitiator is any one of 2-isopropylthioxanthone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone and 2,4-diethylthioxanthone, or a mixture of two or more thereof; the pigment is rutile titanium dioxide; the leveling agent is any one of BYK333 and BYK361N, or a mixture of two or more thereof; and the defoamer is any one of BYK051 and BYK055, or a mixture of two or more thereof.

10. The method for preparing the yellowing-resistant offset LED tinplate ink according to claim 1, characterized in that The steps include: 1) Weigh each reaction raw material according to weight; 2) First, put the pigment, dispersant and acrylic ester active monomer into the sand mill, seal and grind for 30-40 minutes, and filter to obtain the pigment paste after the pigment fineness reaches the required particle size of 1-6μm; 3) Put the liquid rubber modified by silane coupling agent, the silane coupling agent modified acrylate monomer, the photoinitiator, the leveling agent, the defoaming agent and the ground color paste into a sealed planetary mixer for dispersion and stirring. After stirring evenly, filter the material, seal and store it to obtain the yellowing-resistant offset LED tinplate ink.

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