Advertisement inkjet UV ink for PVC soft film and preparation method thereof

Abstract

The invention provides advertisement inkjet UV ink for a PVC soft film and a preparation method thereof.The advertisement inkjet UV ink for the PVC soft film comprises an active diluting monomer, color paste and photoinitiators, the photoinitiators comprise the first photoinitiator and the second photoinitiator, the first photoinitiator is diphenyl-(2, 4, 6-trimethylbenzoyl) phosphorus oxide, the second photoinitiator is 2, 4, 6-trimethylbenzoyl) phosphorus oxide, and the active diluting monomer is an acrylic monomer. The content of the photoinitiator is 7%-10% in percentage by mass, and the content of the 2, 4-diethyl thioxanthone is 10%-20% in percentage by mass; the color paste is different in color, the content ratio of the first photoinitiator to the content ratio of the second photoinitiator are different, and when the color paste is black, the content ratio of the first photoinitiator to the content ratio of the second photoinitiator is (8-9): 2; when the color paste is cyan or magenta, the content ratio of the first photoinitiator to the second photoinitiator is (7-8): (0.1-1); when the color paste is yellow, the content ratio of the first photoinitiator to the second photoinitiator is 8: (1-2). The problems that existing UV ink cannot be completely cured under low light curing energy, and slag falling and white point exposing are prone to occurring are solved.

Description

Technical Field

[0001] The invention relates to the field of UV ink preparation, and in particular to an advertising inkjet UV ink for PVC soft film and a preparation method thereof. Background Art

[0002] PVC soft film is widely used in the advertising industry. With its advantages of high light transmittance, elasticity, non-toxicity and weather resistance, it has become one of the indispensable materials in advertising production. For example, it is used in soft film light boxes, outdoor billboards, brand logos, exhibition displays and other fields.

[0003] Currently in the field of digital inkjet, the inks used on PVC soft films include water-based dyes, water-based pigments, solvent inks, and UV inks. Solvent-based inks are commonly used in the outdoor advertising industry. They can provide excellent color brightness and good weather resistance, and are suitable for outdoor environments. However, solvent-based inks contain volatile organic compounds (VOCs), which are released into the environment during the production of outdoor advertisements, posing a potential threat to human health and the environment. Water-based inks are considered a more environmentally friendly option because they usually contain no or only a small amount of VOCs. However, due to their poor water resistance and durability, the application of water-based inks on outdoor advertising materials is limited, especially in the face of adverse weather conditions such as rain and sunshine, the image may fade, flow or be damaged. Water-based dyes have relatively poor light resistance. UV inks have shown the potential to solve the above problems.

[0004] The photocuring energy used by UV ink is generally 200mJ / cm 2～ 400mJ / cm 2 However, at weaker photocuring energies such as 100 mJ / cm 2～ 200mJ / cm 2 Under these circumstances, due to factors such as low sensitivity of ink, weak light penetration and certain absorption of light by pigments, only the ink on the surface of the printed coating solidifies into a film, while the ink inside is in a liquid or semi-dry state. As a result, in the actual application process, the PVC film is easy to fall off or show white spots when rubbed.

[0005] Therefore, we need to prepare UV ink that can completely cure the inner layer of the layer under low light curing energy, while improving the adhesion on the PCV soft film. Summary of the invention

[0006] The first object of the present invention is to provide a UV ink for advertising inkjet printing on PVC soft film, which is used to solve the problem that the existing UV ink cannot be completely cured under low light curing energy and is prone to slag falling and white spots.

[0007] The second object of the present invention is to provide a method for preparing an advertising inkjet UV ink for PVC soft film, which is used to prepare the above-mentioned advertising inkjet UV ink for PVC soft film.

[0008] To achieve the first purpose of the present invention, the present invention provides an advertising inkjet UV ink for PVC soft film, comprising an active diluent monomer, a color paste and a photoinitiator, wherein the photoinitiator comprises a first photoinitiator and a second photoinitiator, wherein the first photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, and the second photoinitiator is 2,4-diethylthioxanthone, and the content of the photoinitiator is 7% to 10% by mass; the content ratio of the first photoinitiator to the second photoinitiator is determined according to the color of the color paste, when the color paste is black, the content ratio of the first photoinitiator to the second photoinitiator is (8 to 9):2; when the color paste is cyan or magenta, the content ratio of the first photoinitiator to the second photoinitiator is (7 to 8):(0.1 to 1); when the color paste is yellow, the content ratio of the first photoinitiator to the second photoinitiator is 8:(1 to 2).

[0009] As can be seen from the above scheme, the UV ink of the present invention includes two photoinitiators, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and 2,4-diethylthioxanthone. Diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide is a cleavage-type photoinitiator with a low bond cleavage enthalpy. It can decompose to generate styrene free radicals and acyloxy free radicals at a low energy, and quickly react with active monomers / oligomers. At the same time, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide has an electron-donating group, which enhances the absorption performance of light. Therefore, even if the light intensity weakens after the light is absorbed by the pigment and other components, the diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide inside the ink layer can still excite free radicals. 2,4-Diethylthioxanthone is a hydrogen abstraction photoinitiator, which can enhance the efficiency of diphenyl-(2,4,6-trimethylbenzoyl)oxyphosphorescence initiation, especially in the case of thicker coatings or deep curing. 2,4-Diethylthioxanthone is a hydrogen abstraction photoinitiator, which can activate diphenyl-(2,4,6-trimethylbenzoyl) to produce more free radicals, thereby increasing the curing speed and improving the curing depth, and promoting the drying speed of the surface. The ratio of the two is different in different color inks. In black ink, because black pigment fully absorbs light, only the surface of black ink can be completely cured, and light cannot penetrate into the interior. Under the above ratio, 2,4-diethylthioxanthone can activate diphenyl-(2,4,6-trimethylbenzoyl) to produce more free radicals, thereby increasing the curing speed and improving the curing depth, and promoting the drying speed of the surface; in cyan and magenta inks, the light transmission windows of these two colors are in the range of 300nm to 350nm, respectively, and diphenyl-(2,4,6-trimethylbenzoyl) oxyphosphine The absorption wavelength range of is 320nm~400nm, which overlaps with its light transmission window, indicating that this part of the ultraviolet light will not be absorbed by the pigment and enter the interior of the ink layer. Increasing the content of diphenyl-(2,4,6-trimethylbenzoyl) phosphine can promote the curing of the internal ink; in yellow ink, the yellow light transmission window is in the range of 280-350nm, and the absorption wavelength range of 2,4-diethylthioxanthone is in the range of 260-400nm, which overlaps with the yellow light transmission window. Therefore, increasing the content of 2,4-diethylthioxanthone can promote the curing of the deep layer. However, if the proportion of 2,4-diethylthioxanthone is too high, yellowing will occur, which will affect the final image effect. Limiting the photoinitiator to the above ratio takes into account that the concentration of the photoinitiator affects both the curing efficiency and the curing depth. When the concentration of the initiator increases, the light curing rate tends to increase, but if the concentration is too high, it will also affect the stability of the ink. More importantly, the increase in the concentration of the photoinitiator does not mean that the curing depth will also increase. In fact, as the photoinitiator concentration increases, the depth of cure tends to decrease.This is because as the concentration increases, monomers and oligomers will form a polymer gel layer, which will block the light and make it difficult for the light to penetrate to a deeper level for curing. Within the above range, the light curing rate and curing depth can be balanced.

[0010] A further solution is that the active diluent monomer includes a monofunctional monomer and a difunctional monomer, the monofunctional monomer includes a first monofunctional monomer and a second monofunctional monomer, the first monofunctional monomer is selected from at least one of isobornyl acrylate and ethylene-methyl methacrylate copolymer; the second monofunctional monomer includes at least one of cyclotrimethylolpropane methyl acrylate and poly-2-hydroxyethyl acrylate; the difunctional monomer includes neopentyl glycol polymethyl ethylene oxide diacrylate.

[0011] It can be seen from the above scheme that isobornyl acrylate and ethylene-methyl methacrylate copolymer are monomers with low curing thresholds and can be quickly cured under low-intensity ultraviolet rays. Therefore, even when the light intensity inside the ink layer is weak, the two monomers can undergo a curing reaction with free radicals. At the same time, the ester group in isobornyl acrylate interacts with the chlorine atoms or oxidized groups on the surface of PVC through van der Waals forces and other interactions for physical adsorption. Based on the above factors, the adhesion to PVC is enhanced. The methyl methacrylate unit in the ethylene-methyl methacrylate copolymer has a strong polarity, especially the carbonyl group (C=O) and the ester group (COOCH3). These polar groups can form a certain polar interaction with the chlorine atoms in PVC, thereby enhancing the adhesion of the ink to the PVC soft film. Under the action of ultraviolet light, the chlorine atoms of PVC may detach from its surface to form active sites, which interact with the carbonyl group and the ester group, further enhancing the adhesion of the ink. However, due to the bridged ring structure, isobornyl acrylate has certain rigidity and steric hindrance characteristics, which can enhance the friction resistance, but the adaptability to the PVC film with higher flexibility will be reduced; the carbonyl and ester groups of methyl methacrylate have strong adsorption to electrons, so the molecular chain is rigid and can improve the mechanical strength of the film, but the flexibility is relatively poor. By adding a second monofunctional monomer with obvious flexibility, the flexibility of the ink is improved. Cyclotrimethylolpropane methyl acrylate contains a cyclotrimethylolpropane structure, and these groups can interact through hydrogen bonds, so that the crosslinker structure does not become too tight and has poor impact resistance. In addition, hydrogen bonding can reduce the glass transition temperature (Tg) of the material. A lower Tg means that the material can maintain flexibility at a lower temperature, so the ink is not easy to crack under low temperature conditions. Poly-2-hydroxyethyl acrylate also contains hydroxyl groups, which gives the polymer a certain degree of softness. However, adding only monofunctional monomers will result in a slow curing speed. Neopentyl glycol polymethyl oxirane diacrylate is a bifunctional monomer, which enables it to form a cross-linked network with other monomers under ultraviolet light. The cross-linking reaction can be carried out quickly under ultraviolet light, thereby promoting the rapid curing of the ink. At the same time, it synergizes with the photoinitiator. When the photoinitiator generates free radicals, neopentyl glycol polymethyl oxirane diacrylate quickly reacts with the free radicals, thereby increasing the photocuring speed. Furthermore, neopentyl glycol polymethyl oxirane diacrylate is cross-linked with other monomers to form a three-dimensional network. The formation of a three-dimensional network will hinder the oxygen in the air from entering the ink, thereby solving the problem of easy oxidation of isobornyl acrylate and oxygen inhibition reaction during the photocuring process. Ultimately, the photocuring rate is improved, avoiding the stickiness of the printed surface.

[0012] A further solution is that the content ratio between the monofunctional monomer and the difunctional monomer is (2:1) to (3:1).

[0013] It can be seen from the above scheme that if the content of neopentyl glycol polymethyl oxirane diacrylate is too high, neopentyl glycol polymethyl oxirane diacrylate and other monomers will cross-link each other during the photocuring process, thereby forming a large number of three-dimensional networks. The formation of the three-dimensional network will hinder the light from entering the interior of the ink layer, thereby inhibiting the rate at which the initiator produces free radicals, and ultimately reducing the photocuring rate of the internal ink layer, resulting in the printed surface being dry but the interior being sticky. If the content of neopentyl glycol polymethyl oxirane diacrylate is too low, it will not be able to form a sufficient three-dimensional network, resulting in low adhesion of the ink to PVC and a slower curing speed.

[0014] A further solution is that the UV ink also includes a photopolymerizable oligomer, and the photopolymerizable oligomer is an amine-modified resin.

[0015] As can be seen from the above scheme, the amine-modified resin is a transparent substance. The transparent resin can improve the transmittance of light, so that more light can reach the inside of the ink, thereby facilitating the internal curing. A further effect is that the amine-modified resin can react quickly with the ultraviolet light initiator to generate free radicals, which promotes the rapid curing of the ink into a film under ultraviolet light. In addition, it will undergo a cross-linking reaction with the monomers described above, further accelerating the curing speed. In addition, the amine-modified resin has a strong polarity, and interacts with the PVC soft film with a strong polarity, further enhancing the adhesion.

[0016] A further solution is that the content ratio between the active diluent monomer and the photopolymerizable oligomer is (25:1) to (35:1).

[0017] As can be seen from the above scheme, active diluent monomers and photopolymerizable oligomers are the basic materials for UV ink, and their ratio has an important influence on the sensitivity of the ink. Generally speaking, increasing the ratio of active diluent monomers can improve the fluidity of the ink and the penetration of ultraviolet light, thereby accelerating the internal curing speed. However, too much active diluent monomer may affect the hardness and wear resistance of the ink. Under the premise of ensuring the performance of the ink, the ratio of active diluent monomers and oligomers is appropriately adjusted to achieve the best sensitivity.

[0018] A further solution is that the UV ink also includes a leveling agent, and the leveling agent is a polyether siloxane copolymer leveling agent.

[0019] As can be seen from the above scheme, the leveling agent can effectively reduce the surface tension of the ink, improve its fluidity, and enable the ink to be more evenly distributed on the surface of the substrate during the printing process. This helps to avoid defects such as spots and scars on the printed product and makes the ink film surface smoother. The polyether chain of the polyether siloxane copolymer will interact with PVC, further improving the adhesion of the ink.

[0020] A further solution is that, by mass percentage, the color paste includes 50% to 80% of monomers, 0.1% to 5% of dispersants and 15% to 45% of pigments.

[0021] In a further embodiment, the monomer is selected from at least one of isobornyl acrylate, ethylene-methyl methacrylate copolymer, cyclotrimethylolpropane formal acrylate, poly-2-hydroxyethyl acrylate neopentyl glycol polymethylethylene oxide diacrylate.

[0022] In a further embodiment, the dispersant is at least one selected from TEGO 760W, TEGO 740, BYK 163 and BYK 190.

[0023] In a further embodiment, the pigment is selected from at least one of carbon black, CI Pigment Yellow 12, CI Pigment Red 5 and CI Pigment Blue 15:3.

[0024] It can be seen from the above scheme that after grinding the monomer, pigment and dispersant, a color paste with suitable particle size and stable dispersibility can be obtained, which is beneficial to the next step of ink configuration. Among them, the dispersant is selected from one of TEGO 760W, TEGO 740, BYK 163 and BYK 190, which can effectively improve the dispersibility of the pigment, prevent the aggregation of pigments and improve the grinding efficiency.

[0025] A further solution is that, by mass percentage, the UV ink includes 70% to 80% of active diluent monomers, 7% to 20% of color paste, 7% to 10% of photoinitiator, 1% to 3% of photopolymerizable oligomers and 0.05% to 0.2% of leveling agent.

[0026] It can be seen from the above scheme that the UV ink under the above ratio can be in the ultraviolet wavelength range of 200nm~400nm, 100mJ / cm 2 ~200mJ / cm 2 It can be completely cured under high light curing energy, with low curing energy required, better curing efficiency and more energy saving.

[0027] To achieve the second purpose of the present invention, the present invention provides a method for preparing UV ink for advertising inkjet printing of PVC soft film, which is used for preparing UV ink for advertising inkjet printing of PVC soft film described in any of the above schemes, and the preparation method comprises the following steps: S1, according to mass percentage, 50% to 80% of monomer, 0.1% to 5% of dispersant and 15% to 45% of pigment are mixed and stirred, and then added into a grinding machine, and the color paste is obtained after grinding for 3h to 5h; S2, according to mass percentage, active diluent monomer, photoinitiator and leveling agent are mixed, and stirred at 500rpm to 800rpm for 20min to 30min; S3, the color paste obtained in step S1 is added to the solution prepared in the above step S2, and the stirring is continued for 15min to 30min at the speed described in S2; S4, finally, the amine-modified resin is added to the solution prepared in the above step S3, and the stirring is carried out at 800rpm to 1000rpm for 30min to 60min to obtain UV ink. DETAILED DESCRIPTION

[0028] The invention discloses an advertising inkjet printing UV ink for PVC soft film, wherein the UV ink can be used in the ultraviolet light wavelength range of 200nm to 400nm and 100mJ / cm 2～ 200mJ / cm 2 The light curing energy is sufficient to cure the product completely.

[0029] Calculated by mass percentage, the advertising inkjet UV ink for PVC soft film comprises 70% to 80% of active diluent monomer, 7% to 20% of color paste, 7% to 10% of photoinitiator, 1% to 3% of photopolymerizable oligomer and 0.05% to 0.2% of leveling agent.

[0030] The active diluent monomers include monofunctional monomers and difunctional monomers, and the content ratio between the monofunctional monomers and the difunctional monomers is (2:1) to (3:1). The monofunctional monomer includes a first monofunctional monomer and a second monofunctional monomer, and the first monofunctional monomer is selected from at least one of isobornyl acrylate (IBOA) and ethylene-methyl methacrylate copolymer (EMMA); the second monofunctional monomer includes at least one of cyclotrimethylolpropane methyl acrylate (CTFA) and poly-2-hydroxyethyl acrylate (PHEA); the difunctional monomer includes neopentyl glycol polymethyl ethylene oxide diacrylate (NPG2PODA).

[0031] The color paste includes 50% to 80% of monomer, 0.1% to 5% of dispersant and 15% to 45% of pigment, wherein the monomer is; the dispersant is selected from at least one of TEGO 760W, TEGO 740, BYK 163 and BYK 190; and the pigment is selected from at least one of carbon black, CI pigment yellow 12, CI pigment red 5 and CI pigment blue 15:3.

[0032] The photoinitiator includes a first photoinitiator and a second photoinitiator, the first photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), the second photoinitiator is 2,4-diethylthioxanthone (DETX), and the content of the photoinitiator is 7% to 10% by mass; the content ratio of the first photoinitiator to the second photoinitiator is different for different color pastes, when the color paste is black, the content ratio of the first photoinitiator to the second photoinitiator is (8 to 9):2; when the color paste is cyan or magenta, the content ratio of the first photoinitiator to the second photoinitiator is (7 to 8):(0.1 to 1); when the color paste is yellow, the content ratio of the first photoinitiator to the second photoinitiator is 8:(1 to 2).

[0033] The photopolymerizable oligomer is an amine-modified resin, and specifically, the amine-modified resin can be selected from CN371 NS of Sartomer. The content ratio between the active diluent monomer and the photopolymerizable oligomer is (25:1) to (35:1).

[0034] The leveling agent is a polyether siloxane copolymer leveling agent, and specifically, can be selected from at least one of TEGO 432 and TEGO 450.

[0035] The above-mentioned advertising inkjet printing UV ink for PVC soft film can be prepared by the following preparation method, which comprises the following steps:

[0036] S1. According to the mass percentage, 50% to 80% of monomer, 0.1% to 5% of dispersant and 15% to 45% of pigment are mixed and stirred, and then added into a grinding machine, and the color paste is obtained after grinding for 3h to 5h;

[0037] S2. Mix the active diluent monomer, photoinitiator and leveling agent according to mass percentage, and stir at 500 rpm to 800 rpm for 20 min to 30 min;

[0038] S3, adding the color paste obtained in step S1 to the solution prepared in step S2, and continuing to stir at the speed described in S2 for 15 minutes to 30 minutes;

[0039] S4. Finally, the amine-modified resin is added to the solution prepared in the above step S3, and stirred at 800 rpm to 1000 rpm for 30 min to 60 min to obtain UV ink.

[0040] The following is a description with reference to specific embodiments.

[0041] The color paste was prepared according to the proportions shown in Table 1 below.

[0042] Table 1

[0043]

[0044] The advertising inkjet UV ink for PVC soft film was prepared according to the proportions shown in Tables 2 to 4 below.

[0045] Table 2

[0046]

[0047]

[0048] Table 3

[0049]

[0050]

[0051] Table 4

[0052]

[0053]

[0054] The performance of the PVC soft film advertising inkjet UV ink prepared in Table 2, Table 3 and Table 4 was tested. The specific test method is as follows:

[0055] 1. Adhesion

[0056] Mark the color block on the PVC soft film, then use a paint film grid marker to draw 10×10 1mm×1mm small grids on the surface of the test color block, use 3M600 tape (width 25mm, adhesion (10±1)N / 25mm) to firmly stick to the small grid to be tested, and use an eraser to rub the tape hard to increase the contact area and strength between the tape and the tested area, grab one end of the tape by hand, and quickly tear off the tape in a direction close to 60°; determine the adhesion level according to the surface shedding situation: Level 0 - No shedding There are traces of print shedding; Level 1: small pieces of print shedding at the intersection of the lines, and the shedding area is less than 5%; Level 2: small pieces of print shedding at the edges and intersections of the lines, and the total shedding area is between 5% and 15%; Level 3: large pieces of print shedding at the edges and intersections of the lines, and the total shedding area is between 15% and 35%; Level 4: large pieces of print shedding at the edges and intersections of the lines, and the total shedding area is between 35% and 65%; Level 5: the degree of shedding exceeds Level 4.

[0057] 2. Adhesion

[0058] Print color blocks on the PVC soft film according to the test requirements. After confirming that the ink layer is cured, stick the pictures to each other, stick the pictures to the material, and fold them. Apply a flat weight greater than 1kg to the sample, and place the sample and the weight in a 40℃ oven for 24 hours. After opening, check whether the ink layer has faded, fallen off or transferred. Among them, level 1: the picture is not sticky when unfolded, the ink layer does not fall off after unfolding, and the color has not transferred at all; level 2: the picture feels sticky when separated and unfolded, and needs to be torn to separate. There is no color transfer after unfolding, and the picture is intact; level 3: the picture is obviously sticky when unfolded, but the color is slightly transferred to the corresponding bonding surface after unfolding, or a small amount of it falls off, and the total falling area is less than 5% of the test area; level 4: the picture is obviously sticky when unfolded, and after tearing it apart, the color transfers to the corresponding bonding surface or falls off over a large area, and the total falling area is greater than 5% of the test area;

[0059] 3. Stretchability

[0060] Cut the color block into 2cm*10cm strips, fix one end of the strip, fix both ends of the strip along the short side, and stretch it evenly with a stretching instrument at a stretching speed of 50mm / min until the ink cracks or the film breaks; record the stretching rate (stretching rate % = (length after stretching / original length × 100%)).

[0061] 4. Low temperature resistance

[0062] Place the samples in an environmental test box (12 / 15℃) for 30 minutes, keep the temperature constant, and then fold the samples in half in the environmental test box. If there is no cracking or splitting, it is qualified; if there is cracking or splitting, it is unqualified.

[0063] 5. Internal curing performance test

[0064] The ink is printed on the PVC soft film using a multi-pass printer, which means that the nozzle moves back and forth multiple times along the direction of the printing medium during the printing process, and each movement covers a part of the printing medium. The entire image is printed through multiple coverage. After each nozzle prints the ink, the curing energy is 100mJ / cm 2 ~200mJ / cm 2 The test results can be observed from the sample printing effect. If the surface of the sample is smooth and flat, it means that the internal curing effect of the ink is good; if there are wrinkles on the surface, it means that the surface of the ink layer has been completely dried, but the internal curing performance of the ink is poor.

[0065] 6. Rub resistance test

[0066] The specific rubbing resistance test method is: use the same printing conditions in 5 to print the ink on the PVC soft film, rub the printed soft film 3 to 5 times, and observe whether the ink layer has whitening and slag. If not, the rubbing resistance performance is qualified. The specific test results are shown in Tables 5, 6 and 7 below.

[0067] Table 5

[0068]

[0069] Table 6

[0070]

[0071]

[0072] Table 7

[0073]

[0074] It can be seen from Tables 5 to 7 above that in Comparative Example 1, TPO:DETX is 10:2, which exceeds the ratio of (8-9):2; Comparative Example 2 does not contain the first monofunctional monomer; Comparative Example 3 does not contain the second monofunctional monomer, and Comparative Example 4 does not contain the difunctional monomer; the ratio of the monofunctional monomer to the difunctional monomer in Comparative Example 5 is 13:3, which is higher than 3:1; in Comparative Example 6, TPO:DETX is 6:1, which is lower than the ratio of (7-8):(0.1-1); in Comparative Example 7, TPO:DE TX is 9:1, which is higher than the ratio of (7-8): (0.1-1); the content ratio between the active diluent monomer and the photopolymerizable oligomer in Comparative Example 8 is 40.5:1, which is higher than the ratio of (25:1)-(35:1); Comparative Example 9 does not contain photopolymerizable oligomers; Comparative Example 10 TPO:DETX is 8:3, which is lower than the ratio of 8:(1-2). The inks in the above comparative examples are not as good as those in the embodiments in terms of re-adhesion performance, adhesion, low temperature resistance, stretchability, internal curing performance and rubbing resistance.

[0075] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the embodiments of the present disclosure. It should be understood that the above description is only the specific implementation method of the embodiments of the present disclosure and is not intended to limit the protection scope of the embodiments of the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the protection scope of the embodiments of the present disclosure.

Claims

1. A UV ink for advertising printing on PVC soft film, comprising a reactive diluent monomer, a color paste and a photoinitiator, characterized in that: The photoinitiator comprises a first photoinitiator and a second photoinitiator, the first photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, the second photoinitiator is 2,4-diethylthioxanthone, and the content of the photoinitiator is 7% to 10% by mass percentage; The content ratio of the first photoinitiator to the second photoinitiator is determined according to the color of the color paste. When the color paste is black, the content ratio of the first photoinitiator to the second photoinitiator is (8-9):2; when the color paste is cyan or magenta, the content ratio of the first photoinitiator to the second photoinitiator is (7-8):(0.1-1); when the color paste is yellow, the content ratio of the first photoinitiator to the second photoinitiator is 8:(1-2).

2. The advertising inkjet printing UV ink for PVC soft film according to claim 1, characterized in that: The active diluent monomer includes a monofunctional monomer and a difunctional monomer, the monofunctional monomer includes a first monofunctional monomer and a second monofunctional monomer, the first monofunctional monomer is selected from at least one of isobornyl acrylate and ethylene-methyl methacrylate copolymer; the second monofunctional monomer includes at least one of cyclotrimethylolpropane formal acrylate and poly-2-hydroxyethyl acrylate; the difunctional monomer includes neopentyl glycol polymethyl ethylene oxide diacrylate.

3. The advertising inkjet printing UV ink for PVC soft film according to claim 2, characterized in that: The content ratio between the monofunctional monomer and the difunctional monomer is (2:1) to (3:1).

4. The advertising inkjet printing UV ink for PVC soft film according to claim 1, characterized in that: The UV ink further includes a photopolymerizable oligomer, and the photopolymerizable oligomer is an amine-modified resin.

5. The advertising inkjet printing UV ink for PVC soft film as claimed in claim 4, characterized in that: The content ratio between the active diluent monomer and the photopolymerizable oligomer is (25:1) to (35:1).

6. The advertising inkjet printing UV ink for PVC soft film according to claim 1, characterized in that: The UV ink also includes a leveling agent, and the leveling agent is a polyether siloxane copolymer leveling agent.

7. The advertising inkjet UV ink for PVC soft film according to any one of claims 1 to 6, characterized in that: Calculated by mass percentage, the color paste consists of 50% to 80% of monomers, 0.1% to 5% of dispersants and 15% to 45% of pigments.

8. The advertising inkjet printing UV ink for PVC soft film according to claim 7, characterized in that: The pigment is selected from at least one of carbon black, CI Pigment Yellow 12, CI Pigment Red 5 and CI Pigment Blue 15:

3.

9. The advertising inkjet printing UV ink for PVC soft film according to any one of claims 1 to 6, characterized in that: Calculated by mass percentage, the UV ink comprises 70% to 80% of active diluent monomers, 7% to 20% of color paste, 7% to 10% of photoinitiator, 1% to 3% of photopolymerizable oligomers and 0.05% to 0.2% of leveling agent.

10. A method for preparing advertising inkjet UV ink for PVC soft film, characterized in that: Used to prepare the PVC soft film advertising inkjet UV ink as claimed in any one of claims 1 to 9, the preparation method comprises the following steps: S1. According to the mass percentage, 50% to 80% of monomer, 0.1% to 5% of dispersant and 15% to 45% of pigment are mixed and stirred, and then added into a grinding machine, and the color paste is obtained after grinding for 3h to 5h; S2. Mix the active diluent monomer, photoinitiator and leveling agent according to mass percentage, and stir at 500 rpm to 800 rpm for 20 min to 30 min; S3, adding the color paste obtained in step S1 to the solution prepared in step S2, and continuing to stir at the speed described in S2 for 15 minutes to 30 minutes; S4. Finally, the amine-modified resin is added to the solution prepared in the above step S3, and stirred at 800 rpm to 1000 rpm for 30 min to 60 min to obtain the UV ink.

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