LED (light-emitting diode) curing type ink as well as preparation method and use method thereof

Abstract

The invention provides LED (light-emitting diode) curing ink as well as a preparation method and a use method thereof, and belongs to the technical field of ink. The LED curing type ink provided by the invention is prepared from the following raw materials in percentage by mass: 3 to 6 percent of photoinitiator, 8 to 12 percent of active amine, 10 to 25 percent of monomer, 45 to 60 percent of prepolymer, 8 to 15 percent of color paste, 1 to 3 percent of polymethylsiloxane, 1 to 5 percent of fumed silica and 0.5 to 1 percent of wax powder. According to the invention, polymethylsiloxane can form liquid beads with extremely small particle sizes in the ink, and the liquid beads become a phase separation center; the surface tension is very small, a surface tension gradient is generated on a water / oil interface of the liquid beads, ink on the surface is driven to flow, and orange stripes are formed; the fumed silica forms a hydrogen bond network in the ink, the quantity of hydrogen bonds is adjusted by controlling the dosage of the fumed silica, and meanwhile, imbibition of pores on the surface of the paper to the ink is reduced, so that orange patterns with a good visual effect are obtained on the surface of the paper.

Description

Technical Field

[0001] The invention belongs to the technical field of inks, and in particular relates to an LED curable ink and a preparation method and a use method thereof. Background Art

[0002] LED curing technology has the advantages of high energy conversion efficiency, low cost, and environmental friendliness. Compared with traditional UV curing technology, it has lower energy consumption and lower ozone emissions. In addition, due to the low temperature generated by the light source during the curing process, the temperature damage to materials such as paper and plastic is low. These advantages make LED curing inks widely used in label printing, packaging, electronic products, and automotive decoration.

[0003] Orange texture is one of the special effects on the surface of packaging and printing materials, similar to ice flowers, frosting, texture, etc., with a novel and unique visual effect. The formation of orange texture is mainly due to the Bénard vortex effect and surface tension. The Bénard vortex effect is the temperature and surface tension gradient caused by the different evaporation rates of the mixed solvent during the ink drying process, which prompts the flow and vortex inside the ink. This flow makes the ink surface uneven, similar to the natural orange peel texture, which is a surface defect in the paint and coating industry. However, if artificial control is used to produce uniform and beautiful texture, it is a novel surface decoration effect. The technology for preparing orange texture on metal surfaces is relatively mature, but due to the strong ink absorption of paper, the orange texture effect on the paper surface is poor, and orange texture is not common in the decoration of paper box packaging surfaces. Therefore, how to improve the ink so that it can produce a good orange texture effect on the paper surface has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] The purpose of the present invention is to provide an LED curable ink and a preparation method and a use method thereof. The LED curable ink provided by the present invention can form a good orange-strip effect on the surface of paper.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides an LED curable ink, which is prepared from raw materials including the following mass percentages: 3-6% of photoinitiator, 8-12% of active amine, 10-25% of monomer, 45-60% of prepolymer, 8-15% of color paste, 1-3% of polymethylsiloxane, 1-5% of fumed silica and 0.5-1% of wax powder.

[0007] Preferably, it is prepared from raw materials including the following mass percentages: 4-5% photoinitiator, 9-11% active amine, 15-20% monomer, 46-58% prepolymer, 10-12% color paste, 1.5-2.5% polymethylsiloxane, 2-4% fumed silica and 0.6-0.9% wax powder.

[0008] Preferably, the photoinitiator includes at least one of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, di-p-methylphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone and 2,4-diethylthioxanthone.

[0009] Preferably, the monomer includes at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, acryloyl morpholine and trimethylolpropane triacrylate.

[0010] Preferably, the prepolymer comprises at least one of polyurethane acrylate, epoxy acrylate and hyperbranched acrylate.

[0011] The present invention also provides a method for preparing the LED curable ink according to the above technical solution, comprising the following steps:

[0012] (1) mixing a photoinitiator and a monomer to obtain a monomer solution;

[0013] (2) mixing the monomer solution, prepolymer and active amine obtained in step (1) to obtain a mixed solution;

[0014] (3) mixing the mixed solution obtained in step (2), polymethylsiloxane and color paste to obtain an emulsion;

[0015] (4) The emulsion obtained in step (3), fumed silica and wax powder are mixed to obtain an LED curable ink.

[0016] Preferably, the mixing in step (3) is carried out under stirring conditions; the stirring rate is 2500-3500 r / min, and the stirring time is 30-60 min.

[0017] Preferably, the particle size of the droplets in the emulsion in step (3) is 0.1 to 10 μm.

[0018] Preferably, the particle size of the LED curable ink in step (4) is less than 15 μm.

[0019] The present invention also provides a method for using the LED-curable ink described in the above technical solution or the LED-curable ink prepared by the preparation method described in the above technical solution, comprising:

[0020] The LED curable ink is screen printed and cured in sequence.

[0021] The present invention provides an LED curable ink, which is prepared from the following raw materials in mass percentage: 3-6% photoinitiator, 8-12% active amine, 10-25% monomer, 45-60% prepolymer, 8-15% color paste, 1-3% polymethylsiloxane, 1-5% fumed silica and 0.5-1% wax powder. The present invention uses polymethylsiloxane as an orange grain agent, which can form liquid droplets with extremely small particle size in the ink, evenly distributed in the ink, and will form microphase separation after the ink is screen printed, becoming a water / oil phase separation center; at the same time, it has very small surface tension, and the surface tension of other raw materials of the ink is relatively high, so that a large surface tension gradient is generated at the water / oil interface of the liquid droplets, driving the ink flow on the surface to form orange grains; adding fumed silica will form a hydrogen bond network in the ink, and the number of hydrogen bonds is adjusted by controlling the amount of fumed silica, thereby controlling the fluidity of the ink, greatly reducing the absorption of the ink by the pores on the surface of the paper, and then obtaining orange grains with good visual effects on the surface of the paper, which is used for the surface decoration of various packaging paper boxes. Experimental results show that the LED curable ink provided by the present invention can bring unique visual effects and tactile sensations when applied on the surface of paper packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the surface effect of the LED curable ink prepared in Comparative Example 2 after curing;

[0023] Figure 2 This is the surface effect of the LED curable ink prepared in Comparative Example 3 after curing;

[0024] Figure 3 This is the surface effect of the LED curable ink prepared in Comparative Example 4 after curing;

[0025] Figure 4 This is the surface effect of the LED curable ink prepared in Comparative Example 1 after curing;

[0026] Figure 5 This is the surface effect of the LED curable ink prepared in Comparative Example 5 after curing;

[0027] Figure 6 This is the surface effect of the LED curable ink prepared in Comparative Example 6 after curing;

[0028] Figure 7 This is the surface effect of the LED curable ink prepared in Comparative Example 7 after curing;

[0029] Figure 8 is the contact angle of the LED curable ink prepared in Example 1;

[0030] Fig. 9 The contact angle of the LED curable ink prepared in Comparative Example 8;

[0031] Fig.10 This is a photo of the LED curable ink prepared in Example 7, which was cured after being screen printed for 5 minutes;

[0032] Fig.11 This is a photo of the LED curable ink prepared in Example 7 being directly cured by screen printing;

[0033] Fig.12 This is a photo of the LED curable ink prepared in Example 1, which was cured after being screen printed for 5 minutes;

[0034] Fig.13 This is a photo of the LED curable ink prepared in Example 8, which was cured after being screen printed for 5 minutes;

[0035] Fig.14 The LED curable ink prepared in Example 1 is heated to 1 to 200 seconds. -1 Curve of shear viscosity changing with shear rate within the frequency range;

[0036] Fig.15 This is a relationship curve between shear stress and shear rate of the LED curable ink prepared in Example 1;

[0037] Fig.16 This is a relationship curve between the frequency, storage modulus and loss modulus of the LED curable ink prepared in Example 1. DETAILED DESCRIPTION

[0038] The invention provides an LED curable ink, which is prepared from raw materials including the following mass percentages: 3-6% of photoinitiator, 8-12% of active amine, 10-25% of monomer, 45-60% of prepolymer, 8-15% of color paste, 1-3% of polymethylsiloxane, 1-5% of fumed silica and 0.5-1% of wax powder.

[0039] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0040] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 3-6% of photoinitiator, preferably 4-5%; the photoinitiator preferably includes at least one of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, di-p-methylphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone and 2,4-diethylthioxanthone, more preferably bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. In the present invention, the photoinitiator can have strong absorption at a wavelength of 385-405nm and generate sufficient free radicals, and other photoinitiators cannot meet the requirements.

[0041] In the present invention, the mass ratio of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide to 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is preferably 1:4 or 4:1. In the present invention, the mass ratio of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide to 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is controlled within the above range to shorten the curing time.

[0042] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 8-12% active amine, preferably 9-11%, and more preferably 10%. The present invention does not specifically limit the type of the active amine, and active amines well known to those skilled in the art can be used. In the present invention, the active amine can effectively avoid oxygen inhibition, further improve the curing speed and degree of the ink, and solve the problem of poor surface drying of the ink; by controlling the amount of the active amine within the above range, it is possible to avoid excessive yellowing and discoloration after curing and increased brittleness.

[0043] In the present invention, the active amine is preferably RYOJI active amine 008 (RJ10). In the present invention, the active amine is a special bifunctional tertiary amine co-initiator, which can provide a large amount of active hydrogen, effectively avoid oxygen inhibition, and increase UV curing speed.

[0044] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 10-25% of monomers, preferably 15-20%, and more preferably 16-18%; the monomers preferably include at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, acryloyl morpholine and trimethylolpropane triacrylate, preferably acryloyl morpholine (ACMO). In the present invention, the monomers are used for cross-linking and curing; the monofunctional monomer acryloyl morpholine has low viscosity, high solubility in photoinitiators, fast curing rate, low skin irritation, low odor, good compatibility and dispersibility, heat resistance, acid and alkali resistance, low curing shrinkage, and good flexibility; its molecular structure contains hydrophilic morpholine groups and hydrophobic carbon chain structures, and the presence of nitrogen atoms in the molecule can reduce oxygen inhibition, so acryloyl morpholine is preferably used as a monomer.

[0045] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 45-60% prepolymer, preferably 46-58%, and more preferably 47-54.5% prepolymer; the prepolymer preferably includes at least one of polyurethane acrylate, epoxy acrylate, and hyperbranched acrylate. In the present invention, the prepolymer is one of the main components of the ink, and undergoes a cross-linking reaction with other components during the ink curing process, so that the cured ink layer has good paper adhesion, flexibility, and wear resistance.

[0046] As an embodiment, the mass content of the prepolymer may be 48%, 49%, 50%, 51%, 52%, 53% or 54%.

[0047] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 8-15% of the color paste, preferably 10-12%, and more preferably 11%. The present invention has no special limitation on the type of the color paste, and the color paste can be adjusted according to actual needs.

[0048] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 1-3% polymethylsiloxane, preferably 1.5-2.5%. The present invention uses polymethylsiloxane as an orange grain agent, which can form liquid droplets with extremely small particle sizes in the ink, evenly distributed in the ink, and will form microphase separation after the ink is screen printed, becoming a phase separation center; at the same time, it has very small surface tension, and the surface tension of other raw materials of the ink is relatively high, so that a large surface tension gradient is generated at the water / oil interface of the liquid droplets, driving the ink flow on the surface to form orange grains.

[0049] As an implementation manner, the mass content of the polymethylsiloxane may be 2%.

[0050] In the present invention, the active content of the polymethylsiloxane is preferably 60%. As an embodiment, the type of the polymethylsiloxane can be MEM-0349.

[0051] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 1-5% of fumed silica, preferably 1.5-4.5%; the particle size of the fumed silica is preferably 10-14 nm, more preferably 12 nm. In the present invention, the surface of the fumed silica contains a large amount of hydroxyl groups, so that it forms a hydrogen bond network in the ink. By controlling the amount of the fumed silica, the number of hydrogen bonds is adjusted, thereby controlling the fluidity of the ink, and then obtaining orange stripes with good visual effects on the surface of the paper, which is used for the surface decoration of various packaging cartons; at the same time, it can also improve the wear resistance of the ink layer surface and reduce the ink absorption of the paper.

[0052] As an embodiment, the mass content of the fumed silica may be 2%, 2.5%, 3%, 3.5% or 4%.

[0053] In terms of mass percentage, the raw materials for preparing the LED curable ink provided by the present invention include 0.5-1%, preferably 0.6-0.9% wax powder. In the present invention, the wax powder floats to the surface of the ink after the LED curable ink is dried to become a friction contact point, disperse the pressure, further reduce the friction force, and enhance the wear resistance of the ink layer surface.

[0054] In the present invention, the particle size of the wax powder is preferably 5 to 15 μm.

[0055] The present invention uses polymethylsiloxane as an orange grain agent, which can form liquid droplets with extremely small particle sizes in the ink and is evenly distributed in the ink. After the ink is screen-printed, microphase separation is formed to become a phase separation center. At the same time, the polymethylsiloxane has very small surface tension. The surface tension of other raw materials of the ink is relatively high, so a large surface tension gradient is generated at the water / oil interface of the liquid droplets, driving the ink on the surface to flow and forming orange grains. Adding fumed silica will form a hydrogen bond network in the ink. By controlling the amount of the fumed silica, the number of hydrogen bonds is adjusted, thereby controlling the fluidity of the ink, and then obtaining orange grains with good visual effects on the surface of paper, which is used for surface decoration of various packaging cartons.

[0056] The polymethylsiloxane of the present invention has a very low surface tension of about 21 mN / m, while the surface tension of the remaining components in the ink, mainly monomers and prepolymers, is about 40 mN / m. After screen printing, a large surface tension gradient will be generated at the interface in the ink layer. Under the action of the surface tension gradient, the ink flows rapidly to produce orange stripes, and after the orange stripes are produced, it is not easy to level. This innovates the application of polymethylsiloxane, whose original function is a defoaming agent.

[0057] In the present invention, the surface of the fumed silica contains a large amount of hydroxyl groups, which are easy to form a hydrogen bond network in the ink. The number of hydrogen bonds in the ink is controlled according to the amount of fumed silica added. The more hydrogen bonds there are, the more crosslinking points of the hydrogen bond network are formed, the greater the strength is, the greater the yield stress of the ink under the action of external force is, and the ink is not easy to flow. On the contrary, the less the amount of fumed silica added, the easier the ink flows. The formation of orange stripes requires that the fluidity of the ink is within a suitable range. On the one hand, the surface of the ink layer after screen printing is easy to flow and form orange stripes under the drive of the surface tension gradient, and on the other hand, the surface of the ink layer will not level quickly. The present invention utilizes fumed silica to form a hydrogen bond network in the ink. By controlling its dosage, the number of hydrogen bonds in the system and the number of crosslinking points in the hydrogen bond network are controlled, thereby controlling the fluidity of the ink surface within a suitable range. In addition, an appropriate amount of fumed silica can reduce the ink absorption of paper and improve the uniformity and visual effect of the prepared orange stripes.

[0058] The present invention also provides a method for preparing the LED curable ink according to the above technical solution, comprising the following steps:

[0059] (1) mixing a photoinitiator and a monomer to obtain a monomer solution;

[0060] (2) mixing the monomer solution, prepolymer and active amine obtained in step (1) to obtain a mixed solution;

[0061] (3) mixing the mixed solution obtained in step (2), polymethylsiloxane and color paste to obtain an emulsion;

[0062] (4) The emulsion obtained in step (3), fumed silica and wax powder are mixed to obtain an LED curable ink.

[0063] The present invention adopts the above-mentioned adding sequence to improve the uniformity of mixing; in addition, the photoinitiator is solid, and if the wax powder is added first, it is impossible to visually determine whether the photoinitiator is completely dissolved.

[0064] The present invention mixes a photoinitiator and a monomer to obtain a monomer solution.

[0065] The present invention has no special limitation on the operation of mixing the photoinitiator and the monomer, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0066] After obtaining the monomer solution, the present invention mixes the monomer solution, prepolymer and active amine to obtain a mixed solution.

[0067] In the present invention, the mixing of the monomer solution, prepolymer and active amine is preferably carried out under stirring; the stirring rate is preferably 300-500 r / min; and the stirring time is preferably 30-60 min. As an embodiment, the stirring rate may be 400 r / min; and the stirring time may be 40 min or 50 min.

[0068] After obtaining the mixed solution, the present invention mixes the mixed solution, polymethylsiloxane and color paste to obtain an emulsion.

[0069] In the present invention, the mixing of the mixed solution, polymethylsiloxane and color paste is preferably high-speed dispersion; the rate of the high-speed dispersion is 2500-3500 r / min; the time of the high-speed dispersion is preferably 30-60 min. The present invention limits the rate and time of the high-speed dispersion to the above ranges to make the raw materials mixed more uniformly.

[0070] As an embodiment, the high-speed dispersion rate may be 2600 r / min, 2700 r / min, 2800 r / min, 2900 r / min, 3000 r / min, 3100 r / min, 3200 r / min, 3300 r / min or 3400 r / min; the high-speed dispersion time may be 40 min or 50 min.

[0071] In the present invention, the particle size of the droplets in the emulsion is preferably 0.1 to 10 μm.

[0072] After obtaining the emulsion, the present invention mixes the emulsion, fumed silica and wax powder to obtain LED curable ink.

[0073] In the present invention, the mixing of the emulsion, fumed silica and wax powder is preferably carried out under stirring conditions; the stirring rate is preferably 200 to 500 r / min; and the stirring time is preferably 30 to 60 min. As an embodiment, the stirring rate may be 250 r / min; and the stirring time may be 40 min or 50 min.

[0074] After the emulsion, fumed silica and wax powder are mixed, the present invention preferably grinds and vacuum degasses the mixed product in sequence to obtain LED curable ink.

[0075] The present invention has no special limitation on the grinding operation, as long as the particle size of the LED curable ink is less than 15 μm.

[0076] In the present invention, the vacuum degree of the vacuum degassing is preferably 0.1-10Pa; the vacuum degassing is preferably carried out under stirring conditions; the stirring rate is preferably 30-80r / min; and the stirring time is preferably 30-60min. As an embodiment, the vacuum degree of the vacuum degassing can be 0.1-0.5Pa; the stirring rate can be 40-60r / min; and the stirring time can be 40-50min.

[0077] In the present invention, the particle size of the LED curable ink is preferably less than 15 μm.

[0078] The preparation method provided by the invention has simple process and is suitable for industrial production.

[0079] The present invention also provides a method for using the LED-curable ink described in the above technical solution or the LED-curable ink prepared by the preparation method described in the above technical solution, comprising:

[0080] The LED curable ink is screen printed and cured in sequence.

[0081] In the present invention, the screen printing is preferably performed on paper.

[0082] The present invention has no special limitation on the operation of screen printing, and the operation can be performed according to actual needs.

[0083] In the present invention, the curing is preferably carried out under LED lighting conditions; the wavelength of the LED lighting is preferably 385nm; the power of the LED lighting is preferably 1-3kW, more preferably 2kW; the distance between the light source used for the LED lighting and the paper surface is preferably 40-60mm, more preferably 50mm; the paper feed rate during the curing is preferably 40-60m / min, more preferably 50m / min.

[0084] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] The experimental equipment used in the embodiments and comparative examples is shown in Table 1, and the raw materials used are shown in Table 2.

[0086] Table 1 Experimental equipment used in the embodiments and comparative examples

[0087]

[0088] Table 2 Raw materials used in the examples and comparative examples

[0089]

[0090] Example 1

[0091] The LED curable ink is prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 54.5% prepolymer, 10% color paste, 1.5% polymethylsiloxane, 3.5% fumed silica and 0.5% wax powder;

[0092] The photoinitiator is bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 1:4;

[0093] The active amine is RYOJI active amine 008 (RJ10);

[0094] The monomer is acryloylmorpholine;

[0095] The prepolymer is polyurethane acrylate;

[0096] The color paste is original yellow paste;

[0097] The active content of the polymethylsiloxane is 60%, and the model is MEM-0349;

[0098] The particle size of the fumed silica is 12 nm;

[0099] The particle size of the wax powder is 5 to 15 μm;

[0100] The preparation method of the LED curable ink is:

[0101] (1) dissolving a photoinitiator in a monomer to obtain a monomer solution;

[0102] (2) adding the prepolymer and the active amine to the monomer solution obtained in step (1), stirring for 40 minutes using an overhead stirrer at 300 r / min to obtain a mixed solution;

[0103] (3) high-speed dispersing the mixed solution obtained in step (2), polymethylsiloxane and color paste to obtain an emulsion; wherein the high-speed dispersing rate is 2600 r / min and the high-speed dispersing time is 40 min;

[0104] (4) Adding fumed silica and wax powder to the emulsion obtained in step (3) and stirring at 250 r / min for 50 min, and then grinding with a sand mill and a ceramic three-roll grinder until the fineness of the scraper fineness meter is ＜15μm, and finally placed in a vacuum degassing machine for vacuum degassing to obtain LED curing ink; wherein, the vacuum degree of vacuum degassing is 0.1Pa, and the vacuum degassing is carried out under stirring conditions, the stirring rate is 30r / min, and the stirring time is 30min.

[0105] Example 2

[0106] On the basis of Example 1, the type of prepolymer was changed to epoxy acrylate, and other conditions remained unchanged.

[0107] Example 3

[0108] On the basis of Example 1, the type of prepolymer was changed to hyperbranched acrylate, and other conditions remained unchanged.

[0109] The LED curable ink prepared in Examples 1 to 3 was coated on a glass slide, and the ink was cured using an LED curing device. The curing conditions were: LED light source power of 2 kW, wavelength of 385 nm, light outlet distance of 50 mm from the paper, paper feed rate of 50 m / min, and adhesion was tested by the hundred-grid method after curing. The relative result of the flexibility test was to evaluate the cured film after curing on the glass slide by bending it by hand.

[0110] The results show that the ink layer prepared by epoxy acrylate is very brittle, the ink layer prepared by hyperbranched polyester acrylate is less flexible, and the poor cross-linking uniformity leads to inferior paper adhesion than polyurethane acrylate. The ink layer prepared by polyurethane acrylate also has the best flexibility, so polyurethane acrylate is the preferred prepolymer for LED-curable inks.

[0111] Using a DC2T touch screen viscometer, the spring torque was adjusted to 718.7 N·m at room temperature 25°C, and the viscosity of the LED-curable ink prepared in Example 1 was tested at a rotation speed of 200 r / min. The result was 2 Pa·s, which meets the viscosity range of 2 to 3.5 Pa·s required for screen printing ink.

[0112] Example 4

[0113] On the basis of Example 1, the photoinitiator was changed to bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and other conditions remained unchanged.

[0114] Example 5

[0115] On the basis of Example 1, the photoinitiator was changed to 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and other conditions remained unchanged.

[0116] Example 6

[0117] On the basis of Example 1, the mass ratio of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide was modified to 4:1, and other conditions remained unchanged.

[0118] The LED curable ink prepared in Example 1 and Examples 4 to 6 was screen printed and cured in an LED curing machine with a light source power of 2kW. The curing conditions were: LED light source power of 2kW, wavelength of 385nm, light outlet distance of 50mm from paper, paper feed rate of 50m / min, and the ink was well cured. The degree of complete curing was tested by finger pressure method to test the degree of surface dryness. The curing time of the LED curable ink prepared in Example 4 was about 1.5s, the curing time of the LED curable ink prepared in Example 5 was about 1.0s, and the curing time of the LED curable ink prepared in Example 6 was 1.0s; the curing time of the LED curable ink prepared in Example 1 was 0.2s.

[0119] Comparative Example 1

[0120] The LED curable ink is prepared from the following raw materials in percentage by weight: 5% photoinitiator, 10% active amine, 15% monomer, 59% prepolymer, 10% color paste and 1% polymethylsiloxane;

[0121] The photoinitiator is bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 1:4;

[0122] The active amine is RYOJI active amine 008 (RJ10);

[0123] The monomer is acryloylmorpholine;

[0124] The prepolymer is polyurethane acrylate;

[0125] The color paste is original yellow paste;

[0126] The active content of the polymethylsiloxane is 60%, and the model is MEM-0349;

[0127] The preparation method of the LED curable ink is:

[0128] (1) dissolving a photoinitiator in a monomer to obtain a monomer solution;

[0129] (2) adding the prepolymer and the active amine to the monomer solution obtained in step (1), stirring for 40 minutes using an overhead stirrer at 300 r / min to obtain a mixed solution;

[0130] (3) The mixed solution, polymethylsiloxane and color paste obtained in step (2) are dispersed at high speed, and then ground with a sand mill and a ceramic three-roll grinder until the fineness of the scraper fineness meter is ＜ 15μm, and finally placed in a vacuum degassing machine for vacuum degassing to obtain LED curing ink; wherein, the high-speed dispersion rate is 2600r / min, and the high-speed dispersion time is 40min; the vacuum degree of vacuum degassing is 0.1Pa, and the vacuum degassing is carried out under stirring conditions, the stirring rate is 30r / min, and the stirring time is 30min.

[0131] Comparative Example 2

[0132] Based on Comparative Example 1, polymethylsiloxane was omitted, and other conditions remained unchanged, that is, the LED curable ink was prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 60% prepolymer and 10% color paste.

[0133] Comparative Example 3

[0134] On the basis of Comparative Example 1, polymethylsiloxane was replaced by orange grain agent A, and other conditions remained unchanged.

[0135] Comparative Example 4

[0136] On the basis of Comparative Example 1, polymethylsiloxane was replaced by orange grain agent B, and other conditions remained unchanged.

[0137] The LED curable ink prepared in Comparative Examples 1 to 4 was screen printed on silver card paper and cured with an LED curing machine; wherein the screen mesh number was 150 meshes, the screen tension was 15N, and the angle was 90°; the curing conditions were: LED 385nm light source, 2kW, the light source was 50mm from the paper surface, and the paper feed rate was 50m / min.

[0138] The surface effect of the LED curable ink prepared in Comparative Example 2 after curing is as follows: Figure 1 As shown; the surface effect of the LED curable ink prepared in Comparative Example 3 after curing is as follows Figure 2 As shown; the surface effect of the LED curable ink prepared in Comparative Example 4 after curing is as follows Figure 3 As shown; the surface effect of the LED curable ink prepared in Comparative Example 1 after curing is as follows Figure 4 shown.

[0139] from Figures 1 to 4 It can be seen that the orange peel texture produced by the two orange peel agents purchased on the market is not clear and the three-dimensional effect is not good; the best orange peel effect is obtained when polymethylsiloxane is used as the orange peel agent.

[0140] The sample obtained by curing the LED-curable ink prepared in Comparative Example 1 was left for a week and it was found that the orange peel effect remained basically unchanged.

[0141] Comparative Example 5

[0142] The LED curable ink is prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 59.5% prepolymer, 10% color paste and 0.5% polymethylsiloxane, and other conditions are the same as those in Comparative Example 1.

[0143] Comparative Example 6

[0144] The LED curable ink is prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 58.5% prepolymer, 10% color paste and 1.5% polymethylsiloxane, and other conditions are the same as those in Comparative Example 1.

[0145] Comparative Example 7

[0146] The LED curable ink is prepared from the following raw materials in mass percentage: 5% photoinitiator, 10% active amine, 15% monomer, 58% prepolymer, 10% color paste and 2% polymethylsiloxane. Other conditions are the same as those in Comparative Example 1.

[0147] The LED curable ink prepared in Comparative Example 1 and Comparative Examples 5 to 7 was screen printed on silver card paper and cured with an LED curing machine; wherein the screen mesh number was 150 meshes, the screen tension was 15N, and the angle was 90°; the curing conditions were: LED 385nm light source, 2kW, the light source was 50mm away from the paper surface, and the paper feed rate was 50m / min.

[0148] The surface effect of the LED curable ink prepared in Comparative Example 5 after curing is as follows: Figure 5 As shown; the surface effect of the LED curable ink prepared in Comparative Example 6 after curing is as follows Figure 6 As shown; the surface effect of the LED curable ink prepared in Comparative Example 7 after curing is as follows Figure 7 shown.

[0149] from Figures 4 to 7It can be seen that when 0.5% polymethylsiloxane is used, the three-dimensional effect is not obvious and the glossiness is not good; when 1.0% polymethylsiloxane is used, the orange-texture visual effect is poor; when 1.5% polymethylsiloxane is used, the three-dimensional effect, orange-texture effect and glossiness are appropriate; when 2.0% polymethylsiloxane is used, the three-dimensional effect of orange-texture is weakened, indicating that different polymethylsiloxane contents have different effects on the texture. As the polymethylsiloxane content increases, the surface tension gradient gradually increases, and the texture gradually becomes three-dimensional and clear; but when the polymethylsiloxane content reaches a certain level, the three-dimensional effect begins to weaken. Therefore, the orange-texture effect is good when the polymethylsiloxane content is about 1.5%.

[0150] Comparative Example 8

[0151] The LED curable ink is prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 58% prepolymer, 10% color paste, 1.5% polymethylsiloxane and 0.5% wax powder. Other conditions are the same as in Example 1, i.e., fumed silica is omitted.

[0152] The water contact angle of the LED-curable ink prepared in Example 1 and Comparative Example 8 was tested using a video contact angle meter of model DSA100. The test steps were as follows: the video contact angle meter was powered on, a syringe filled with distilled water was mounted on a fixed frame, printed samples cut to the same size were placed on a workbench, a drop of liquid was flowed out of the rotating micrometer head onto the sample surface, and after standing for 1 second, an image of the water drop on the sample surface was collected.

[0153] Figure 8 is the contact angle of the LED curable ink prepared in Example 1; Fig. 9 This is the contact angle of the LED-curable ink prepared in Comparative Example 8.

[0154] from Figures 8-9 It can be seen that the contact angle of Comparative Example 8 is 57.2°, and the contact angle of Example 1 is 79.5°, indicating that the addition of fumed silica can reduce the ink absorption of paper.

[0155] Example 7

[0156] The LED curable ink is prepared from the following raw materials in percentage by weight: 5% photoinitiator, 10% active amine, 15% monomer, 55.5% prepolymer, 10% color paste, 1.5% polymethylsiloxane, 2.5% fumed silica and 0.5% wax powder. Other conditions are the same as in Example 1.

[0157] Example 8

[0158] The LED curable ink is prepared from the following raw materials in percentage by mass: 5% photoinitiator, 10% active amine, 15% monomer, 53.5% prepolymer, 10% color paste, 1.5% polymethylsiloxane, 4.5% fumed silica and 0.5% wax powder. Other conditions are the same as in Example 1.

[0159] The LED curable ink prepared in Examples 1 and 7 to 8 was screen printed (screen mesh number was 150 mesh, screen tension was 15N, angle was 90°), and then LED cured (curing conditions were: LED light source power was 2kW, wavelength was 385nm, light outlet was 50mm away from paper, paper feed rate was 50m / min). The cured photos are shown in FIG. Figures 10 to 13 , Fig.10 This is a photo of the LED curable ink prepared in Example 7, which was cured after being screen printed for 5 minutes; Fig.11 This is a photo of the LED curable ink prepared in Example 7 being directly cured by screen printing; Fig.12 This is a photo of the LED curable ink prepared in Example 1, which was cured after being screen printed for 5 minutes; Fig.13 This is a photograph of the LED-curable ink prepared in Example 8, which was cured after being screen-printed for 5 minutes.

[0160] from Figures 10 to 13 It can be seen that a small amount of fumed silica can greatly change the viscosity and fluidity of LED curing ink; when the content of fumed silica is low, the ink viscosity is low and the orange peel is easy to level; when the content of fumed silica is 2.5%, the height of the orange peel is significantly reduced after standing for 5 minutes after screen printing; when the amount of fumed silica added is 3.5%, the LED curing ink has suitable fluidity and is easy to screen print. After printing, uniform texture appears on the surface, and it will not level and disappear after being placed for a period of time. After LED curing, the orange peel effect is good; when the content of fumed silica is high (4.5%), the viscosity is too high, and the LED curing ink does not have obvious concave and convex textures under the surface tension of polymethylsiloxane. Therefore, it is more appropriate to add about 3.5% of fumed silica to LED curing ink.

[0161] The shear viscosity, yield stress and viscoelasticity of the LED curable ink prepared in Example 1 were tested using a HR-10-TA rheometer.

[0162] Fig.14 The LED curable ink prepared in Example 1 is heated to 1 to 200 seconds. -1 Shear viscosity versus shear rate over the frequency range.

[0163] from Fig.14It can be seen that the static viscosity of the LED curable ink prepared in Example 1 is 5.882 Pa·s. -1 In the region of , the viscosity rapidly thins; when the shear rate is greater than 100s -1 , the highest viscosity is 2Pa·s, with typical shear-thinning characteristics, showing non-Newtonian fluid; oil LED curing ink becomes thinner under the action of screen printing scraper, which is conducive to passing through the mesh; in a static state, it recovers to a higher viscosity, is not easy to level, and is conducive to forming orange peels with good three-dimensional effects. Therefore, the viscosity of LED curing ink is 2Pa·s, and shear thinning performance is one of the rheological characteristics for obtaining good orange peel effects.

[0164] Use the shear rate and the corresponding shear stress to draw the rheological curve and perform the linear fitting of the Bingham fluid model. The Bingham model is suitable for fluids with a certain yield stress:

[0165] τ=τ B +η B ·γFormula I;

[0166] Where τ is the shear stress, τ B is the yield stress, η B is the flow coefficient of the model, and γ is the shear rate.

[0167] The yield stress value obtained after fitting is used to measure the flow velocity. Fig.15 This is the relationship curve between shear stress and shear rate of the LED curable ink prepared in Example 1.

[0168] from Fig.15 It can be seen that there is no excessive residual stress in the wet film of the LED-curable ink of Example 1 after screen printing, which reduces defects such as silver streaks and spots caused by the flow of the LED-curable ink under the action of residual stress. This linear relationship of the LED-curable ink is conducive to obtaining a uniform orange-striped effect.

[0169] Fig.16 This is a relationship curve between the frequency, storage modulus (G') and loss modulus (G") of the LED-curable ink prepared in Example 1, and the setting parameters are: constant strain, variable frequency (1-200 Hz), and temperature 25°C; the storage modulus represents the energy stored due to elastic reversible deformation during the deformation of the ink, and characterizes the elastic characteristics of the ink; the loss modulus represents the energy lost due to irreversible viscous deformation during the deformation of the ink, and characterizes the viscous characteristics of the ink.

[0170] from Fig.16It can be seen that the intersection of the two lines is the flow point of the ink (813.9Pa); in the low-frequency region with a frequency less than 140.9Hz, G'>G", that is, within a very short stress time, the ink will not flow and appear in a solid state, indicating that the ink has good stability; as the frequency gradually increases, G' and G" have an intersection, when the shear rate is higher than 140.9Hz, G'<G", the LED-curable ink flows and appears as a fluid and can flow; the larger the intersection value, the less likely the LED-curable ink is to flow; to obtain a good orange-peel effect, the ink needs to have appropriate fluidity, therefore, the intersection value of the storage modulus and loss modulus of the LED-curable ink, 813.9Pa, can be used as a reference value for the viscoelasticity of the ink to obtain a good orange-peel effect.

[0171] The performance of the LED curable ink prepared in Example 1 was tested, as shown in Table 3.

[0172] Table 3 Performance data of LED curable ink prepared in Example 1

[0173] project index Test results Detection Methods Status in the container After stirring, there is no lumps qualified GB / T13217 Fineness / μm ≤15 12.5 GB / T13217.3 Viscosity (25℃) / Pa·s Agreed 2 GB / T13217.4 Adhesion fastness / % ≥85 ≥90 GB / T13217.7 Tinting strength / % 90～110 90 GB / T13217.6

[0174] In summary, the application of LED curing ink on the surface of paper packaging can bring unique visual effects and tactile sensations. The present invention obtains LED curing orange-textured ink with good adhesion, fast drying speed and high curing degree by rationally compounding the raw materials. The preferred formula is: 1% of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (819), 4% of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 10% of RYOJI active amine 008 (RJ10) %, 15% acrylamide morpholine, 54.5% polyurethane acrylate, 10% color paste, 1.5% polymethylsiloxane, 3.5% fumed silica and 0.5% wax powder; rheological test shows that the viscosity of LED curing ink is 2Pa·s, and it has shear thinning characteristics; the flow point of LED curing ink is: modulus 813.9Pa, corresponding frequency is 140.9Hz; LED curing ink is environmentally friendly and energy-saving, with a simple preparation process, adding an orange-texture visual element to the innovative paper box packaging.

[0175] It can be seen from the above embodiments and comparative examples that the LED curable ink provided by the present invention can form a good orange-strip effect on the surface of paper.

[0176] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An LED curable ink is prepared from the following raw materials in percentage by mass: 3-6% photoinitiator, 8-12% active amine, 10-25% monomer, 45-60% prepolymer, 8-15% color paste, 1-3% polymethylsiloxane, 1-5% fumed silica and 0.5-1% wax powder.

2. The LED curable ink according to claim 1, characterized in that: The invention is prepared from the following raw materials in percentage by weight: 4-5% of photoinitiator, 9-11% of active amine, 15-20% of monomer, 46-58% of prepolymer, 10-12% of color paste, 1.5-2.5% of polymethylsiloxane, 2-4% of fumed silica and 0.6-0.9% of wax powder.

3. The LED curable ink according to claim 1 or 2, characterized in that: The photoinitiator includes at least one of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, di-p-methylphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone and 2,4-diethylthioxanthone.

4. The LED curable ink according to claim 1 or 2, characterized in that: The monomer includes at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, acryloyl morpholine and trimethylolpropane triacrylate.

5. The LED curable ink according to claim 1 or 2, characterized in that: The prepolymer includes at least one of polyurethane acrylate, epoxy acrylate and hyperbranched acrylate.

6. The method for preparing the LED curable ink according to any one of claims 1 to 5, comprising the following steps: (1) mixing a photoinitiator and a monomer to obtain a monomer solution; (2) mixing the monomer solution, prepolymer and active amine obtained in step (1) to obtain a mixed solution; (3) mixing the mixed solution obtained in step (2), polymethylsiloxane and color paste to obtain an emulsion; (4) The emulsion obtained in step (3), fumed silica and wax powder are mixed to obtain an LED curable ink.

7. The preparation method according to claim 6, characterized in that: The mixing in step (3) is carried out under stirring conditions; the stirring rate is 2500-3500 r / min, and the stirring time is 30-60 min.

8. The preparation method according to claim 6, characterized in that: The particle size of the droplets in the emulsion in step (3) is 0.1 to 10 μm.

9. The preparation method according to claim 6, characterized in that: The particle size of the LED curable ink in step (4) is less than 15 μm.

10. A method for using the LED-curable ink according to any one of claims 1 to 5 or the LED-curable ink prepared by the preparation method according to any one of claims 6 to 9, comprising: The LED curable ink is screen printed and cured in sequence.

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