A yellowing-resistant offset printing LED iron printing ink and its preparation method

Abstract

The present invention provides a yellowing-resistant offset printing LED tinplate ink, which is prepared from acrylate active monomers, liquid rubber modified by a silane coupling agent, acrylate monomers modified by a silane coupling agent, a photoinitiator, pigments, a dispersant, a leveling agent, and an antifoaming agent. The present invention also provides a preparation method for the yellowing-resistant offset printing LED tinplate ink. The yellowing-resistant offset printing LED tinplate ink provided by the present invention can achieve deep curing through the way of alkoxy hydrolysis condensation curing of LED and the silane coupling agent. By introducing liquid rubber modified by a silane coupling agent and acrylate monomers modified by a silane coupling agent, the yellowing resistance, flexibility, plasticity, cohesive strength, and adhesion of the ink film are improved, so that the tinplate ink of the present invention has the characteristics of good yellowing resistance and deep drawing processing performance.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, relates to the fields of coatings and inks, and specifically relates to a yellowing-resistant offset printing LED iron printing ink and a preparation method thereof. Background Art

[0002] At present, with the booming development of the packaging industry, iron packaging or metal packaging is used more and more due to its unique properties. Correspondingly, the demand and application of iron printing inks are also very extensive. As people's requirements for packaging quality continue to improve, the performance requirements for iron printing inks are also getting higher and higher.

[0003] With the increasing attention to iron printing inks, there are more and more related majors. The invention patent with the application number 201811553003.2 discloses an LED light-curing iron printing ink and a preparation method thereof. The composition of the ink is in parts by weight: 30-60 parts of prepolymer, 6-30 parts of reactive monomer diluent, 10-12 parts of photoinitiator, 20-40 parts of pigment, and 2-4 parts of auxiliary agent. Through the component design of the ink, a mixture of highly functional polyurethane acrylate, special modified acrylate, modified polyester acrylate, and amine-modified polyether acrylate is selected as the main resin to provide the framework component on the surface of the ink layer. It has a fast drying speed under the LED light source, a high hardness on the surface of the ink layer, good scratch resistance, and good adhesion. Another example is the invention patent with the application number 202210538127.3, which provides a lithographic printing LED iron printing ink capable of deep drawing processing and a preparation method thereof. By weight, the lithographic printing LED iron printing ink comprises 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 reactive monomer, 20-30 parts of pigment, 10-30 parts of filler, 3-8 parts of photoinitiator, 0.5-5 parts of leveling agent, 0.1-0.5 parts of defoaming agent, and 0.5-1 part of dispersant.

[0004] After the iron printing ink is dried, it generally involves stamping or reshaping, which puts higher requirements on the toughness and adhesion of the iron printing ink. In order to improve the toughness, adhesion, and deep drawing processability, the above patents all use polyurethane-based modified components. Due to the molecular structure characteristics of polyurethane-based substances, they have certain flexibility and good adhesion. However, due to the core molecular structure of polyurethane, the urethane structure, its yellowing resistance, heat resistance, hydrolysis resistance, etc. are relatively poor, which will bring other negative impacts to the ink during actual use. For example, during the LED curing process or the thermal oxygen aging process, the coating containing the urethane 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 printing LED iron printing ink and a preparation method thereof, and the yellowing-resistant offset printing LED iron printing ink and the preparation method thereof are to solve the technical problem that the offset printing LED iron printing ink in the prior art is prone to yellowing during processing.

[0006] The present invention provides a yellowing-resistant offset printing LED iron printing ink, which is prepared from the following raw materials in parts by weight:

[0007] 40-80 parts of acrylate active monomer;

[0008] 10-30 parts of liquid rubber modified with silane coupling agent;

[0009] 10-30 parts of acrylate monomer modified with silane coupling agent;

[0010] 8-10 parts of photoinitiator;

[0011] 20-40 parts of pigment;

[0012] 1-2 parts of dispersant;

[0013] 0.5-2 parts of leveling agent;

[0014] 0.1-0.5 part of defoamer.

[0015] Further, the acrylate active monomer is any one or a mixture of two or more of ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, and polyethylene glycol dimethacrylate.

[0016] Further, the liquid rubber modified with silane coupling agent has a molecular weight in the range of 1000-50000, and contains more than 2 silane coupling agent grafting structures at both ends or middle branched chains of the molecular chain, and the rubber main body is any one or a mixture of two or more of polyisobutylene liquid rubber, styrene-butadiene copolymer liquid rubber, polyisoprene liquid rubber, and polybutadiene liquid rubber.

[0017] Further, the silane coupling agent is any one or a mixture of two or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0018] Specifically, the polybutadiene liquid rubber is selected from any one of POLYVEST110 and POLYVEST130 of Evonik; the polyisoprene liquid rubber is selected from ROCEOIL LIR50 of Rock Oil; the polyisobutylene liquid rubber is selected from HRDF350 of Shandong Hongrui; the styrene-butadiene copolymer liquid rubber is selected from LSBR-4 type of Yilufei Technology.

[0019] Further, the silane-grafted liquid rubber is prepared by the following method: Weigh 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. Use a twin-screw extrusion reaction technology for grafting reaction. The screw temperature is set as follows: the temperature of zones 1 - 3 is 30°C, zone 4 is 60°C, zone 5 is 80°C, zone 6 is 100°C, zone 7 is 140°C, zone 8 is 180°C, zones 9 - 12 are 190°C, zone 13 is 150°C, and the head temperature is 120°C. After the material comes out, it is packed in a sealable stainless steel barrel for standby; the peroxide is tert-amyl peroxy (2-ethylhexyl) carbonate (the peroxide product Luperox TAEC of Arkema).

[0020] Further, the grafting rate of the silane coupling agent-modified liquid rubber is evaluated by infrared absorption. When the grafting rate reaches more than 50%, it can be considered to meet the expected index, and the remaining part of the silane coupling agent is mixed as a free additive component in the next step.

[0021] Further, for the silane coupling agent-modified acrylate monomer, one end contains an acrylate structure and the other end contains a silane coupling agent graft structure.

[0022] Specifically, the preparation method of the silane coupling agent-modified acrylate monomer comprises the following steps:

[0023] 1) Add the bifunctional acrylate monomer to a reaction kettle equipped with a thermometer and a dropping funnel;

[0024] 2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0025] 3) Start stirring and heat to 70 - 80°C at the same time. Drop the solution in step 2) evenly into the bifunctional acrylate monomer and react for 1 - 3 h to obtain the silane coupling agent-modified acrylate.

[0026] Further, the molar ratio of the bifunctional acrylate monomer to the silane coupling agent is 1.2 to 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 or a mixture of two or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane; the thermal initiator is any one of azobisisobutyronitrile or benzoyl peroxide.

[0027] Further, the bifunctional acrylate monomer is one or a mixture of any several 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.

[0028] Further, the photoinitiator is any one or a mixture of two or more of 2-isopropylthioxanthone, diphenyl-(2,4,6-trimethylbenzoyl)oxophosphine, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholin-1-one, and 2,4-diethylthioxanthone.

[0029] Further, the pigment is rutile titanium dioxide.

[0030] Further, the dispersant is selected from any one or a mixture of two or more of DISPERBYK-111 of BYK Chemie, DISPERBYK-2013 of BYK Chemie, and DISPERBYK-2030 of BYK Chemie.

[0031] Further, the leveling agent is BYK361N.

[0032] Further, the defoaming agent is selected from any one or a mixture of two or more of BYK1797 and BYK055.

[0033] The present invention also provides a preparation method of a yellowing-resistant offset printing LED iron printing ink, comprising the following steps;

[0034] Weigh each reaction raw material according to parts by weight;

[0035] First, put the pigment, dispersant, and acrylate active monomer into a sand mill, seal and grind for 30 - 40 min. Wait until the fineness of the pigment reaches the required particle size of 1 - 6 μm, and filter to obtain a pigment paste;

[0036] The liquid rubber modified with a silane coupling agent, the acrylate monomer modified with a silane coupling agent, a photoinitiator, a leveling agent, an antifoaming agent, and the milled color paste are put into a sealed and stirred planetary mixer for dispersion and stirring. After stirring evenly, it is filtered and discharged, and stored in a sealed manner to obtain the yellowing-resistant offset printing LED iron printing ink described above.

[0037] In order to improve the processing performance of iron printing ink in deep drawing or shaping, etc., improve the flexibility and adhesion of LED iron printing ink, and at the same time enhance the yellowing resistance of iron printing ink, the present invention provides an iron printing ink with good adhesion on the metal surface, good flexibility, good yellowing resistance, good heat resistance, good water resistance and other physical properties, and can be deep drawn.

[0038] The liquid rubber modified with a silane coupling agent adopted in the present invention has flexibility. The glass transition temperature of the liquid rubber is generally below zero, and it can act as a toughening agent in the system during the deep drawing process. At the same time, the grafted structure of the silane coupling agent can, after printing and contacting a small amount of moisture, cause the hydrolysis and polycondensation reaction of the siloxane structure to form a crosslinked structure. At the same time, the silane coupling agent can also form a covalent bond with the metal surface to enhance the adhesion of the ink to the metal surface.

[0039] The acrylate monomer modified with a silane coupling agent adopted in the present invention can react with the liquid rubber modified with a silane coupling agent to form a linking bridge between the liquid rubber and the acrylate crosslinked resin to link the liquid rubber and the acrylate resin, enhancing the overall strength of the ink binder resin. At the same time, the modified silane coupling agent structure also has the effect of enhancing the adhesion to the metal.

[0040] Since the present invention does not contain the urethane structure of polyurethane, the yellowing resistance after ink printing is good, and the water resistance is also better than that of products containing urethane.

[0041] Compared with the existing technology, the technical effect of the present invention is positive and obvious. The offset printing LED iron printing ink provided by the present invention that can be deep drawn can achieve deep curing through the way of hydrolysis and condensation curing of the alkoxy groups of LED and the silane coupling agent. By introducing the liquid rubber component, since the glass transition temperature of the rubber is dozens of degrees below zero, it allows a certain displacement of the molecular chain during the deep drawing process, and eliminates the internal stress during the processing through the conformational change of the molecular chain. At the same time, the liquid rubber modified with a silane coupling agent and the acrylate monomer modified with a silane coupling agent are used in combination, and the hydrolysis and condensation of the alkoxy groups effectively improve the overall strength after the ink is cured. At the same time, the silane coupling agent can also form a chemical bond with the metal surface, which is beneficial to improving the adhesion. Specific Embodiments

[0042] Example 1

[0043] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out by using a twin-screw extrusion reaction technology. Polyisobutylene liquid rubber (HRDF350 from Shandong Hongrui) is graft-modified with 3-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent). The screw temperatures are set as follows: the temperatures of zones 1-3 are 30°C, zone 4 is 60°C, zone 5 is 80°C, zone 6 is 100°C, zone 7 is 140°C, zone 8 is 180°C, zones 9-12 are 190°C, zone 13 is 150°C, and the head temperature is 120°C. According to 100 kg of liquid rubber, 0.5 kg of silane coupling agent, and 0.05 kg of the peroxide product Luperox TAEC from Arkema, the silane coupling agent graft-modified liquid rubber is obtained;

[0044] Silane Coupling Agent Modified Acrylate Monomer: 3-(Methacryloyloxy)propyltriethoxysilane (silane coupling agent) modifies the bifunctional acrylate monomer diethylene glycol dimethacrylate: 1.2 mol of bifunctional acrylate monomer; 1 mol of silane coupling agent 3-(methacryloyloxy)propyltriethoxysilane, and the thermal initiator azobisisobutyronitrile accounts for 1‰ of the total mass of the reaction raw materials;

[0045] (1) Add the bifunctional acrylate monomer (diethylene glycol dimethacrylate) to a reaction kettle equipped with a thermometer and a dropping funnel;

[0046] (2) Dissolve the thermal initiator azobisisobutyronitrile in the vinyl silane coupling agent 3-(methacryloyloxy)propyltriethoxysilane and place it in the dropping funnel;

[0047] (3) Start stirring and heat to 70-80°C at the same time. Drop the solution in step (2) evenly into the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0048] Ink Preparation:

[0049] First, put 20 kg of rutile titanium dioxide pigment, 1 kg of dispersant (DISPERBYK-111 from BYK Chemie), and 40 kg of acrylate monomer ethoxylated trimethylolpropane triacrylate into a sand mill, seal and grind for 30 min. Wait until the pigment fineness reaches the required particle size of 1-6 μm, and filter to obtain the pigment paste. Put the ground paste, 10 kg of silane coupling agent modified liquid rubber, 10 kg of silane coupling agent modified acrylate monomer, 8 kg of photoinitiator 2-isopropylthioxanthone, 0.5 kg of leveling agent (BYK361N), and 0.1 kg of defoaming agent (BYK1797) into a planetary mixer for sealed stirring. After stirring evenly, filter and discharge, and store in a sealed manner to obtain the LED printing ink for iron;

[0050] Example 2

[0051] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out by using a twin-screw extrusion reaction technology. Styrene-butadiene copolymer liquid rubber (LSBR-4 type of Yilufei Technology) is graft-modified with vinyltriethoxysilane (silane coupling agent). The screw temperatures are set as follows: the temperatures of zones 1-3 are 30 °C, zone 4 is 60 °C, zone 5 is 80 °C, zone 6 is 100 °C, zone 7 is 140 °C, zone 8 is 180 °C, zones 9-12 are 190 °C, zone 13 is 150 °C, and the head temperature is 120 °C. According to 100 kg of liquid rubber, 3 kg of silane coupling agent, and 0.15 kg of peroxide TAEC, the silane coupling agent graft-modified liquid rubber is obtained;

[0052] Silane Coupling Agent Modified Acrylate Monomer: Vinyltrimethoxysilane (silane coupling agent) modifies the bifunctional acrylate monomer dipropylene glycol diacrylate: 1.5 mol of bifunctional acrylate monomer; 1 mol of silane coupling agent, and the thermal initiator benzoyl peroxide accounts for 3‰ of the total mass;

[0053] (1) Add the bifunctional acrylate monomer (dipropylene glycol diacrylate) into a reaction kettle equipped with a thermometer and a dropping funnel;

[0054] (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0055] (3) Start stirring and heat to 70-80 °C at the same time. Slowly add the solution in step (2) dropwise into the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0056] Ink Preparation:

[0057] First, put 40 kg of rutile titanium dioxide pigment, 2 kg of dispersant (DISPERBYK-2013 of BYK Chemie), and 80 kg of acrylate monomer propoxylated glycerol triacrylate into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1-6 μm, and then filter to obtain the pigment paste. Put the ground paste, 30 kg of silane coupling agent modified liquid rubber, 30 kg of silane coupling agent modified acrylate monomer, 10 kg of photoinitiator diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, 2 kg of leveling agent (BYK361N), and 0.5 kg of defoaming agent (BYK055) into a planetary mixer with sealed stirring. After stirring evenly, filter and discharge, and store it in a sealed manner to obtain the described LED printing ink for iron.

[0058] Example 3

[0059] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out by using a twin-screw extrusion reaction technology. POLYVEST 110 of polybutadiene liquid rubber produced by Evonik is graft-modified with 3-methacryloxypropyltriethoxysilane (silane coupling agent). The screw temperatures are set as follows: the temperatures of zones 1-3 are 30°C, zone 4 is 60°C, zone 5 is 80°C, zone 6 is 100°C, zone 7 is 140°C, zone 8 is 180°C, zones 9-12 are 190°C, zone 13 is 150°C, and the head temperature is 120°C. According to 100 kg of liquid rubber, 2 kg of silane coupling agent, and 0.1 kg of peroxide TAEC, the silane coupling agent graft-modified liquid rubber is obtained;

[0060] Silane Coupling Agent Modified Acrylate Monomer: Vinyltriethoxysilane (silane coupling agent) modified acrylate monomer 2-methyl-1,3-propanediol diacrylate: 1.3 mol of bifunctional acrylate monomer, 1 mol of silane coupling agent, and the thermal initiator azobisisobutyronitrile accounts for 2‰ of the total mass;

[0061] (1) Add the bifunctional acrylate monomer (2-methyl-1,3-propanediol diacrylate) to a reaction kettle equipped with a thermometer and a dropping funnel;

[0062] (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0063] (3) Start stirring and heat to 70-80°C at the same time. Slowly add the solution in step (2) dropwise to the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0064] Ink Preparation:

[0065] First, put 30 kg of rutile titanium dioxide pigment, 1.5 kg of dispersant (DISPERBYK-2030 from BYK Chemie), and 60 kg of acrylate monomer pentaerythritol triacrylate into a sand mill, seal and grind for 35 min. Wait until the pigment fineness reaches the required particle size of 1-6 μm, and filter to obtain the pigment paste. Put the ground paste, 20 kg of silane coupling agent modified liquid rubber, 20 kg of silane coupling agent modified acrylate monomer, 9 kg of photoinitiator 2-methyl-1-[4-(methylthio)phenyl]-2-morpholin-1-propanone, 1 kg of leveling agent (BYK361N), and 0.3 kg of defoaming agent (BYK1797) into a planetary mixer with sealed stirring. After stirring evenly, filter and discharge, and store it in a sealed manner to obtain the described LED printing ink for iron.

[0066] Example 4

[0067] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out by using a twin-screw extrusion reaction technology. Vinyltrimethoxysilane (silane coupling agent) is used to graft-modify polyisoprene liquid rubber ROCEOIL LIR50 of Rock Petroleum. The screw temperatures are set as follows: the temperatures of zones 1-3 are 30°C, zone 4 is 60°C, zone 5 is 80°C, zone 6 is 100°C, zone 7 is 140°C, zone 8 is 180°C, zones 9-12 are 190°C, zone 13 is 150°C, and the head temperature is 120°C. According to 100 kg of liquid rubber, 1.5 kg of silane coupling agent, and 0.08 kg of peroxide TAEC, the silane coupling agent graft-modified liquid rubber is obtained;

[0068] Silane Coupling Agent Modified Acrylate Monomer: Vinyltriethoxysilane (silane coupling agent) modifies acrylate monomers 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate: 1.4 mol of bifunctional acrylate monomer, 1 mol of silane coupling agent, and benzoyl peroxide as the thermal initiator accounts for 1.7‰ of the total mass;

[0069] (1) Add the bifunctional acrylate monomer (1,3-butanediol diacrylate) to a reaction kettle equipped with a thermometer and a dropping funnel;

[0070] (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0071] (3) Start stirring and heat to 70-80°C at the same time. Slowly add the solution in step (2) dropwise to the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0072] Ink Preparation:

[0073] First, put 35 kg of rutile titanium dioxide pigment, 1.6 kg of dispersant (DISPERBYK-2030 of BYK Chemie), and 50 kg of acrylate monomer polyethylene glycol diacrylate into a sand mill, seal and grind for 38 min. Wait until the particle size of the pigment reaches the required 1-6 μm, and filter to obtain the pigment paste. Put the ground paste, 25 kg of silane coupling agent modified liquid rubber, 15 kg of silane coupling agent modified acrylate monomer, 10 kg of photoinitiator 2,4-diethylthioxanthone, 1.4 kg of leveling agent (BYK361N), and 0.2 kg of defoaming agent (BYK055) into a planetary mixer with sealed stirring. After stirring evenly, filter and discharge, and store it sealed to obtain the described LED printing ink for tinplate.

[0074] Example 5

[0075] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out by using a twin-screw extrusion reaction technology. Polybutadiene liquid rubber (POLYVEST 130 of Evonik) is graft-modified with vinyltriethoxysilane (silane coupling agent). The screw temperatures are set as follows: the temperatures of zones 1-3 are 30 °C, zone 4 is 60 °C, zone 5 is 80 °C, zone 6 is 100 °C, zone 7 is 140 °C, zone 8 is 180 °C, zones 9-12 are 190 °C, zone 13 is 150 °C, and the head temperature is 120 °C. According to 100 kg of liquid rubber, 2.5 kg of silane coupling agent, and 0.07 kg of peroxide TAEC, the silane coupling agent graft-modified liquid rubber is obtained;

[0076] Silane Coupling Agent Modified Acrylate Monomer: Vinyltrimethoxysilane (silane coupling agent) modified acrylate monomer 1,3-butanediol dimethacrylate: 1.5 mol of bifunctional acrylate monomer, 1 mol of silane coupling agent, and the thermal initiator azobisisobutyronitrile accounts for 1.6‰ of the total mass;

[0077] (1) Add the bifunctional acrylate monomer (1,3-butanediol dimethacrylate) to a reaction kettle equipped with a thermometer and a dropping funnel;

[0078] (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0079] (3) Start stirring and heat to 70-80 °C at the same time. Drop the solution in step (2) evenly into the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0080] Ink Preparation:

[0081] First, put 40 kg of rutile titanium dioxide pigment, 1.2 kg of dispersant (DISPERBYK-2013 of BYK Chemie), and 75 kg of acrylate monomer polyethylene glycol dimethacrylate into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1-6 μm, and filter to obtain the pigment paste. Put the ground paste, 26 kg of silane coupling agent modified liquid rubber, 18 kg of silane coupling agent modified acrylate monomer, 9 kg of photoinitiator 2-isopropylthioxanthone, 1.2 kg of leveling agent (BYK361N), and 0.2 kg of defoaming agent (BYK1797) into a planetary mixer with sealed stirring. After stirring evenly, filter and discharge, and store it in a sealed manner to obtain the described LED printing ink for iron sheets.

[0082] Example 6

[0083] Silane Coupling Agent Modified Liquid Rubber: The grafting reaction is carried out using a twin-screw extrusion reaction technique. Polybutadiene liquid rubber is graft-modified with 3-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent). The screw temperatures are set as follows: the temperatures of zones 1-3 are 30 °C, zone 4 is 60 °C, zone 5 is 80 °C, zone 6 is 100 °C, zone 7 is 140 °C, zone 8 is 180 °C, zones 9-12 are 190 °C, zone 13 is 150 °C, and the head temperature is 120 °C. According to 100 kg of liquid rubber, 0.8 kg of silane coupling agent, and 0.11 kg of peroxide TAEC, the silane coupling agent graft-modified liquid rubber is obtained;

[0084] Silane Coupling Agent Modified Acrylate Monomer: 3-(Methacryloyloxy)propyltrimethoxysilane (silane coupling agent) modifies the acrylate monomer neopentyl glycol diacrylate and an equal proportion of 1,6-hexanediol dimethacrylate: 1.5 mol of bifunctional acrylate monomer; 1 mol of silane coupling agent, and the thermal initiator azobisisobutyronitrile accounts for 2‰ of the total mass;

[0085] (1) Add the bifunctional acrylate monomer neopentyl glycol diacrylate to a reaction kettle equipped with a thermometer and a dropping funnel;

[0086] (2) Dissolve the thermal initiator in the vinyl silane coupling agent and place it in the dropping funnel;

[0087] (3) Start stirring and heat to 70-80 °C at the same time. Slowly add the solution in step (2) dropwise to the bifunctional acrylate monomer and react for 1-3 h to obtain the silane coupling agent modified acrylate monomer;

[0088] Ink Preparation:

[0089] First, put 40 kg of rutile titanium dioxide pigment, 1.3 kg of dispersant (DISPERBYK-111 from BYK Chemie), 40 kg of acrylate monomer ethoxylated trimethylolpropane triacrylate, and 40 kg of pentaerythritol triacrylate into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1-6 μm, and filter to obtain the pigment paste. Put the ground paste, 20 kg of silane coupling agent modified liquid rubber, 10 kg of silane coupling agent modified acrylate monomer, 10 kg of photoinitiator 2,4-diethylthioxanthone, 1.7 kg of leveling agent (BYK361N), and 0.2 kg of defoaming agent (BYK055) into a planetary mixer with sealed stirring. After stirring evenly, filter and discharge, and store in a sealed manner to obtain the described LED printing ink for iron.

[0090] Comparative Example 1

[0091] First, put 40 kg of rutile titanium dioxide pigment;

[0092] Dispersant 1.5 kg (DISPERBYK-2013 from BYK Chemie);

[0093] Acrylate monomer ethoxylated trimethylolpropane triacrylate 40 kg;

[0094] Pentaerythritol triacrylate 110 kg;

[0095] Photoinitiator 2,4 - diethylthioxanthone 10 kg;

[0096] Leveling agent (BYK361N) 1.7 kg;

[0097] Defoamer (BYK1797) 0.3 kg;

[0098] Put into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1 - 6 μm, filter and discharge, and store in a sealed manner to obtain the described LED tinplate printing ink.

[0099] Comparative Example 2

[0100] First, 40 kg of rutile titanium dioxide pigment;

[0101] Dispersant (DISPERBYK-2013 from BYK Chemie) 1.2 kg;

[0102] Acrylate monomer polyethylene glycol dimethacrylate 119 kg;

[0103] Photoinitiator 2 - isopropylthioxanthone 9 kg;

[0104] Leveling agent (BYK361N) 1.2 kg;

[0105] Defoamer (BYK1797) 0.2 kg;

[0106] Put into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1 - 6 μm, filter and discharge, and store in a sealed manner to obtain the described LED tinplate printing ink.

[0107] Comparative Example 3

[0108] 70 kg of alicyclic side chain modified polyurethane acrylate;

[0109] Epoxidized soybean oil modified acrylate 10 kg;

[0110] 1,6 - hexanediol diacrylate 10 kg;

[0111] Ethoxylated pentaerythritol tetraacrylate 10 kg (Guojing Chemistry);

[0112] 30 kg of rutile titanium dioxide;

[0113] 10 kg of talcum powder;

[0114] 9 kg of diphenyl-(2,4,6-trimethylbenzoyl) oxyphosphine;

[0115] 0.5 kg of leveling agent (BYK361N);

[0116] 0.3 kg of defoaming agent (BYK1797);

[0117] 0.7 kg of dispersant (DISPERBYK-2030 of BYK Chemie);

[0118] Put into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1 - 6 μm, filter and discharge the material, and store it in a sealed manner to obtain the described LED tinplate printing ink.

[0119] Comparative Example 4

[0120] 80 kg of alicyclic side chain modified polyurethane acrylate;

[0121] 10 kg of epoxy soybean oil modified acrylate;

[0122] 10 kg of 1,6-hexanediol diacrylate (Changxing Chemical);

[0123] 10 kg of ethoxylated pentaerythritol tetraacrylate (Guojing Chemical);

[0124] 30 kg of rutile titanium dioxide;

[0125] 10 kg of talcum powder;

[0126] 9 kg of photoinitiator 2-isopropylthioxanthone;

[0127] 0.5 kg of leveling agent (BYK361N);

[0128] 0.4 kg of defoaming agent (BYK1797);

[0129] 0.5 kg of dispersant (DISPERBYK-111 of BYK Chemie);

[0130] Put into a sand mill, seal and grind for 40 min. Wait until the pigment fineness reaches the required particle size of 1 - 6 μm, filter and discharge the material, and store it in a sealed manner to obtain the described LED tinplate printing ink.

[0131] Perform performance comparison on the tinplate printing inks provided in the above examples and comparative examples. The test methods are as follows:

[0132] Print the ink on tinplate of the same specification under the same conditions;

[0133] Yellowing resistance: The printed test samples are subjected to UV aging for 100 hours under the same conditions, and the yellowing index (YI) increment before and after aging is compared. The greater the increment, the poorer the yellowing resistance performance.

[0134] Flexibility: Fold at 180° and observe for cracking.

[0135] The adhesion of the coating film is measured according to the methods of GB / T9286 - 1998 and ISO2409:1992.

[0136] Impact resistance: Falling weight impact tester.

[0137] The test data of each example and the comparative example are shown in Table 1:

[0138]

[0139] Through the comparison of yellowing after UV aging under the same conditions, the yellowing index of the ink in the examples is significantly lower after UV aging, indicating good yellowing resistance performance. Through the folding experiment, no cracking occurred in the examples. The impact resistance performance is all above 70. Through comprehensive evaluation, the comprehensive performance of the examples in terms of yellowing resistance, adhesion and impact resistance is excellent.

[0140] The reason analysis in combination with the compositional differences is as follows:

[0141] (1) Introduce liquid rubber modified by silane coupling agent and acrylate monomer modified by silane coupling agent. Since these two materials do not contain nitrogen atoms in their molecular structures, mainly carbon - carbon bonds, carbon - hydrogen bonds, silicon - oxygen bonds, etc., it is not easy to form chromophores and has good yellowing resistance performance.

[0142] (2) Introduce the component of liquid rubber modified by silane coupling agent. Since there are many flexible molecular chain segments in the rubber molecular structure that can undergo a certain displacement, it allows the molecular chains to have a certain displacement during the deep - drawing process. Through the conformational change of the molecular chains, part of the internal stress during the processing can also be eliminated. The introduction of the rubber structure improves the flexibility and plasticity of the material.

[0143] (3) Introduce the silane coupling agent grafting structure, which can form a cross - linked structure through hydrolysis and condensation. On the one hand, it improves the bonding strength between rubber phases and between rubber phase and acrylate phase, thereby enhancing the overall cohesive strength of the ink film and making it less likely to be damaged during the deep - drawing process. On the other hand, the silane coupling agent at the metal interface can also form chemical bonds with the metal surface, enhancing the adhesion between the ink film and the metal, and thus enhancing the adhesion of the ink film to the substrate.

[0144] In Examples 1-6, the use of liquid rubber modified with silane coupling agent and acrylate monomer modified with silane coupling agent improved the properties of the ink film in terms of yellowing resistance, flexibility, plasticity, cohesive strength of the material, adhesion, etc.

[0145] In Comparative Examples 1 and 2, no toughening component was added. Although the yellowing resistance was good, due to poor toughness and adhesion, the ink film burst during the bending comparison test.

[0146] In Comparative Examples 3 and 4, a polyurethane component was added, which improved the flexibility of the ink film, resulting in good impact resistance and deep drawing processability of the ink film. However, due to the molecular structure containing urethane, the nitrogen atom in it is prone to form chromophores, making the yellowing resistance of the overall ink film significantly worse.

Claims

1. A yellowing-resistant offset printing LED iron printing ink, characterized in that It is prepared from the following raw materials in parts by weight: 40 - 80 parts of acrylate active monomer; 10 - 30 parts of liquid rubber modified with silane coupling agent; 10 - 30 parts of acrylate monomer modified with silane coupling agent; 8 - 10 parts of photoinitiator; 20 - 40 parts of pigment; 1 - 2 parts of dispersant; 0.5 - 2 parts of leveling agent; 0.1 - 0.5 parts of defoamer; The liquid rubber modified with silane coupling agent contains more than 2 silane coupling agent grafting structures at both ends or middle side chains of the molecular chain, and its rubber main body is any one or a mixture of two or more of polyisobutylene liquid rubber, styrene - butadiene copolymer liquid rubber, polyisoprene liquid rubber, and polybutadiene liquid rubber. The silane coupling agent is any one or a mixture of two or more of 3 - (methacryloyloxy)propyltrimethoxysilane, 3 - methacryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane; The liquid rubber modified with silane coupling agent is prepared by the following method: Weigh 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. Use a twin - screw extrusion reaction technology for grafting reaction. The screw temperatures are set as follows: the temperatures of zones 1 - 3 are 30°C, zone 4 is 60°C, zone 5 is 80°C, zone 6 is 100°C, zone 7 is 140°C, zone 8 is 180°C, zones 9 - 12 are 190°C, zone 13 is 150°C, and the head temperature is 120°C. The peroxide is tert - amyl peroxy (2 - ethylhexyl) carbonate; The acrylate monomer modified with silane coupling agent has an acrylate structure at one end and a silane coupling agent grafting structure at the other end; The preparation method of the acrylate monomer modified with silane coupling agent includes the following steps: 1) Add a bifunctional acrylate monomer to a reaction kettle equipped with a thermometer and a dropping funnel; 2) Dissolve a thermal initiator in a vinyl silane coupling agent and place it in the dropping funnel; 3) Start stirring and heat to 70 - 80°C at the same time. Drop the solution in step 2) evenly into the bifunctional acrylate monomer and react for 1 - 3 h to obtain the acrylate monomer modified with silane coupling agent.

2. The yellowing-resistant offset printing LED iron printing ink according to claim 1, wherein The acrylate active monomer is any one or a mixture of two or more of ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, and polyethylene glycol dimethacrylate.

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

4. A yellowing-resistant offset printing LED iron printing ink according to claim 1, characterized in that, The bifunctional acrylate monomer is one or any mixture 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, polyethylene glycol (400) dimethacrylate.

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

6. The preparation method of a yellowing-resistant offset printing LED iron printing ink according to claim 1, characterized in that It includes the following steps: 1) Weigh each reaction raw material according to parts by weight; 2) First, put the pigment, dispersant, and acrylate active monomer into a sand mill, seal and grind for 30 - 40 min. Wait until the fineness of the pigment reaches the required particle size of 1 - 6 μm, and filter to obtain the pigment paste; 3) Put the liquid rubber modified by silane coupling agent, the acrylate monomer modified by silane coupling agent, photoinitiator, leveling agent, defoaming agent, and the ground paste into a planetary mixer for sealed stirring and dispersion. After stirring evenly, filter and discharge, and store it in a sealed manner to obtain the yellowing-resistant offset printing LED iron printing ink.

Images