UV white ink for specialty paper as well as preparation method and application of UV white ink

Abstract

The invention provides UV white ink for specialty paper as well as a preparation method and application of the UV white ink. The UV white ink is prepared from the following raw materials in percentage by mass: 20 to 24 weight percent of polyurethane acrylic resin, 8 to 12 weight percent of epoxy acrylic resin, 8 to 12 weight percent of acrylic ester, 45 to 65 weight percent of titanium dioxide, 0.5 to 1.5 weight percent of wax powder, 5 to 7 weight percent of photosensitizer and 0.5 to 1.5 weight percent of heat stabilizer, wherein the molecular weight of the polyurethane acrylic resin is 20,000-100,000; the particle size of the titanium dioxide is less than 0.36 mu m, the particle size distribution is 0.25-0.36 mu m, and the density is 0.38-0.42 g / cm < 2 >. The UV white ink has the advantages that by adding the ultra-high molecular weight UV resin for improving the flexibility and dispersity and the auxiliaries into the formula, the folding resistance and the friction resistance of the white ink can be improved, the adhesive force of the UV white ink is improved, and meanwhile, the titanium dioxide with excellent performance is added, so that the covering rate and the whiteness of the UV white ink are very good.

Description

Technical Field

[0001] The present application relates to the field of ink technology, and in particular to a UV white ink for special paper and a preparation method thereof, special paper using the UV white ink, and special paper. Background Art

[0002] Due to its natural dark tone and long fiber structure, the printed pattern of specialty paper is relatively dark, and it is difficult to achieve the brightness of ordinary pink paper. Especially those specialty papers with colors, such as red, yellow, black, and brown, are often affected by the background color and paper fibers during printing, making the color effect unsatisfactory. In order to solve this problem and achieve the same brightness as white cardboard printing, it is usually necessary to apply a layer of white background (i.e. white ink) on the specialty paper before printing text or patterns. This layer of white background can effectively reduce the influence of the background color and paper fibers on the printing effect, ensuring that the final color effect meets expectations.

[0003] Existing white ink often performs well in hiding power and can effectively cover the base color to achieve a good hiding effect. However, in terms of adhesion, the performance of white ink is not satisfactory. Adhesion is a key factor affecting the quality and durability of printed products. In order to improve the adhesion of white ink, some ink manufacturers will add additives such as slip agents and dimethyl silicone oil to it in order to enhance the adhesion between the ink and the printing material. However, these additives often have a negative impact on the fluidity and hiding power of the ink and color overprinting, so that white ink sacrifices some hiding and interlayer adhesion effects while improving adhesion. Therefore, under the existing technical conditions, it is difficult to meet the hiding power and adhesion of white ink at the same time, and it is necessary to make trade-offs and adjustments according to actual needs during the production process.

[0004] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Summary of the invention

[0005] In view of at least one problem of the above-mentioned prior art, a first object of the present invention is to provide a UV white ink for special paper, which comprises the following raw materials in mass percentage:

[0006] 20-24wt% polyurethane acrylic resin, 8-12wt% epoxy acrylic resin, 8-12wt% acrylate, 45-65wt% titanium dioxide, 0.5-1.5wt% wax powder, 5-7wt% photosensitizer and 0.5-1.5wt% heat stabilizer;

[0007] Wherein, the molecular weight of the polyurethane acrylic resin is 20,000 to 100,000;

[0008] The particle size of the titanium dioxide is less than 0.36 μm, the particle size distribution is 0.25 to 0.36 μm, and the density is 0.38 to 0.42 g / cm 2 .

[0009] In some embodiments of the present application, when the substrate is kraft paper, the color values ​​of the UV white ink after printing are L: 77.66, a: 3.09, b: 1.4, C: 3.39, H: 24.36°; color difference range: color difference value △E<1.

[0010] In some embodiments of the present application, the fineness of the UV white ink is less than 5 μm.

[0011] In some embodiments of the present application, the purity of the titanium dioxide is greater than 99.9%.

[0012] The second object of the present application is to provide a method for preparing any of the above-mentioned UV white inks, which comprises the following steps:

[0013] S1: Mixing polyurethane acrylic resin, epoxy acrylic resin, acrylate, titanium dioxide, wax powder, photosensitizer and heat stabilizer, stirring evenly and leaving for a predetermined time to allow the mixed pigment to be fully wetted; and

[0014] S2: Grinding the mixed pigment after being placed for the predetermined time, so that the mixed pigment reaches a predetermined fineness.

[0015] In some embodiments of the present application, the predetermined time is greater than 4 hours, and the predetermined fineness is less than 5 μm.

[0016] The third object of the present application is to provide a special paper, the surface of which is printed with the UV white ink described in any one of claims 1 to 4.

[0017] In some embodiments of the present application, printing is performed by offset printing.

[0018] In some embodiments of the present application, the substrate of the specialty paper is kraft paper.

[0019] The fourth object of the present application is to provide a printed product, which is made by printing text and / or patterns on any of the special papers described above.

[0020] The invention can improve the folding resistance and friction resistance of white ink and the adhesion of UV white ink by adding ultra-high molecular weight UV resin and additives that increase flexibility and dispersibility into the formula, and at the same time, titanium dioxide with excellent performance is added to make the covering rate and whiteness of UV white ink very good.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings:

[0023] Figure 1 The figure is a schematic diagram of a process flow for preparing UV white ink according to an embodiment of the present invention.

[0024] Figure 2 This is the pattern printed in Example 1 of the present invention.

[0025] Figures 3 to 5 These are the patterns printed in Comparative Examples 1 to 3 of the present invention. DETAILED DESCRIPTION

[0026] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0027] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0028] As used herein, "about" or "approximately" includes the stated value and means within an acceptable range of deviation from the particular value as determined by one skilled in the art, taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0029] The following is a more detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings and examples, so that the scheme of the present invention and its advantages in various aspects can be better understood. However, the specific embodiments and examples described below are only for the purpose of illustration, rather than for limiting the present invention.

[0030] The UV white ink for special paper provided in the present application includes the following raw materials: polyurethane acrylic resin, epoxy acrylic resin, acrylate, titanium dioxide, wax powder, photosensitizer and heat stabilizer.

[0031] Among them, in the UV white ink, the mass percentage of the polyurethane acrylic resin is 20 to 24wt%. The polyurethane acrylic resin used in this application is an ultra-high molecular weight polyurethane acrylic resin with a molecular weight of 20,000 to 100,000. Due to the very large molecular weight, the flexibility and dispersibility of the polyurethane acrylic resin are very good, which makes the prepared UV white ink have good folding and friction resistance. In some specific embodiments, the mass percentage of the polyurethane acrylic resin may be 20wt%, 20.5wt%, 21wt%, 21.5wt%, 22wt%, 22.5wt%, 23wt%, 23.5wt% or 24wt%. In some specific embodiments, the molecular weight of the polyurethane acrylic resin may be 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000 or 100,000. Optionally, the polyurethane acrylate resin includes at least one of a polyurethane acrylate oligomer with an average functionality of 2 to 6 and a modified polyurethane acrylate oligomer with an average functionality of 2 to 6.

[0032] The mass percentage of epoxy acrylic resin is 8-12wt%. Epoxy acrylic resin mainly plays the role of light curing in the present invention. In some specific embodiments, the mass percentage of epoxy acrylic resin can be 8wt%, 9wt%, 10wt%, 11wt% or 12wt%. Optionally, epoxy acrylic resin includes at least one of bisphenol A epoxy acrylate with an average functionality greater than 2, rosin-modified epoxy acrylic resin, long-chain fatty acid-modified epoxy acrylic resin, anhydride-modified epoxy acrylate oligomer, amine-modified epoxy acrylate oligomer, etc. The mass percentage of acrylate is 8-12wt%. Acrylate mainly plays the role of diluent in the present invention. In some specific embodiments, the mass percentage of acrylate can be 8wt%, 9wt%, 10wt%, 11wt% or 12wt%. Optionally, the acrylate includes at least one of trimethylolpropane triacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, propoxylated neopentyl glycol diacrylate, trimethylolpropane trimethacrylate, ethoxylated acrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, diacrylate and dipentaerythritol hexaacrylate.

[0033] The mass percentage of titanium dioxide is 45-65wt%. The particle size of the titanium dioxide used in the present invention is less than 0.36μm, the particle size distribution is between 0.25 and 0.36μm, and the density is 0.38-0.42g / cm 2 . The titanium dioxide used in the present invention has a small particle size, a narrow particle size distribution, and a high density, which is beneficial to improving the coverage and whiteness of UV white ink. Optionally, the titanium dioxide used in the present invention is a surface-treated titanium dioxide, and the surface is coated with silicon dioxide, so that the glossiness, dispersibility, and chemical resistance are greatly improved. Optionally, the titanium dioxide can also use rutile titanium dioxide produced by the chloride process. Optionally, the purity of the titanium dioxide used is higher than 99.9wt%, for example, 99.99wt%, and the higher the purity, the more beneficial it is to improve the whiteness of UV white ink. In some specific embodiments, the mass percentage of titanium dioxide may be 45wt%, 47wt%, 49wt%, 51wt%, 53wt%, 55wt%, 57wt%, 59wt%, 61wt%, 63wt% or 65wt%.

[0034] The mass percentage of the wax powder is 0.5-1.5wt%. The wax powder in the present invention mainly plays a role of wear resistance, as an anti-scratch auxiliary agent. In some specific embodiments, the mass percentage of the wax powder can be 0.5wt%, 0.7wt%, 0.9wt%, 1.1wt%, 1.3wt% or 1.5wt%. Optionally, the wax powder includes at least one of polyethylene wax, fluorine-modified wax powder, polytetrafluoroethylene wax, etc.

[0035] The mass percentage of the photosensitizer is 5-7wt%. In the present application, the photosensitizer is used as a UV desiccant. In some specific embodiments, the mass percentage of the photosensitizer may be 5wt%, 5.5wt%, 6wt%, 6.5wt% or 7wt%. Optionally, the photosensitizer includes at least one of benzophenone, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 2,4,6(trimethylbenzoyl)diphenylphosphine oxide, isopropylthioxanthine (mixture of 2,4 isomers), 2,4-diethylthioxanthine and 1-hydroxy-cyclohexyl-phenyl ketone.

[0036] The mass percentage of the heat stabilizer is 0.5 to 1.5 wt%. The heat stabilizer in the present invention mainly plays the role of improving the adhesion of the ink as a storage stabilizer. In some specific embodiments, the mass percentage of the heat stabilizer may be 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.1 wt%, 1.3 wt% or 1.5 wt%. Optionally, the heat stabilizer includes at least one of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt, 2-phenol ethoxy acrylate, ethoxy mono-oil triacrylate and hydroquinone.

[0037] The invention can improve the folding resistance and friction resistance of white ink by adding ultra-high molecular weight UV resin and additives that increase flexibility and dispersibility into the formula, thereby improving the adhesion of UV white ink. At the same time, titanium dioxide with excellent performance is added to make the covering rate and whiteness of UV white ink very good.

[0038] Optionally, when the substrate is kraft paper, the color values ​​of the UV white ink after printing are L: 77.66, a: 3.09, b: 1.4, C: 3.39, H: 24.36°; color difference range: color difference value △E < 1. It can be seen that the UV white ink provided by the present invention has high whiteness, which is beneficial to the subsequent printing of special paper, and can make the subsequently printed text and patterns, especially colored text and patterns, more exquisite.

[0039] Optionally, the fineness of the UV white ink is less than 5 μm. The smaller the fineness, the more favorable it is for coverage and whiteness.

[0040] Optionally, the solid content of the UV white ink provided in the present application is 100%.

[0041] Figure 1 A method for preparing the above-mentioned UV white ink provided in an embodiment of the present application is shown, comprising the following steps S1 and S2.

[0042] S1: Mix polyurethane acrylic resin, epoxy acrylic resin, acrylate, titanium dioxide, wax powder, photosensitizer and heat stabilizer, stir evenly and place for a predetermined time to make the mixed pigment fully wet.

[0043] Optionally, a planetary mixer is used for stirring. Further optionally, the stirring time is 30 to 50 minutes. In some specific embodiments, the stirring time can be 30 minutes, 35 minutes, 40 minutes, 45 minutes or 50 minutes.

[0044] Optionally, the predetermined time is greater than 4 hours. The pigment is allowed to stand for more than 4 hours until it is fully moistened before grinding.

[0045] S2: Grinding the mixed pigment after being placed for a predetermined time to make the mixed pigment reach a predetermined fineness.

[0046] Optionally, a three-roll mill is used to grind at least 2 times so that the mixed pigment reaches a predetermined fineness. The pressure of the three-roll mill can be set according to the fineness requirement, and the fineness can be detected using a fineness meter. Optionally, the predetermined fineness is <5 μm.

[0047] Optionally, the prepared UV white ink is subjected to a three-roll mill to remove air bubbles and then can be packaged.

[0048] The present application further provides a special paper, the surface of which is printed with any of the above-mentioned UV white inks.

[0049] For example, the specialty paper may be kraft paper or any specialty paper with color. UV white ink may be printed onto the paper surface by offset printing.

[0050] The special paper provided by the present invention has very good flexibility. When the special paper is folded in half, the UV white ink at the fold has no cracks. The "no cracks" mentioned in the present invention means that after the special paper is folded in half once, the UV white ink at the fold is visually observed, and the UV white ink is still a continuous film layer without disconnection.

[0051] The special paper provided by the present invention does not drop ink. The 3M610 tape is used to compact the surface of the special paper where the UV white ink is printed, and then it is quickly pulled up vertically at 90 degrees without ink falling off. It can be seen that the UV white ink provided by the present invention has strong adhesion on the fiber.

[0052] The present invention also provides a printed product, which is formed by printing text and / or patterns on the above-mentioned special paper. Optionally, the text and / or pattern is printed using color ink. Since a layer of UV white ink is printed on the surface of the special paper used, the whiteness is high, so the printed product provided by the present invention is bright in color.

[0053] The present invention is described below with reference to specific embodiments. The process condition values ​​taken in the following embodiments are all exemplary, and the possible numerical ranges are as shown in the above invention content. For process parameters not specifically noted, conventional techniques can be used. Unless otherwise specified, the detection methods used in the following embodiments are conventional detection methods in the industry. Unless otherwise specified, the reagents and instruments used in the technical solutions provided by the present invention can be purchased from conventional channels or the market.

[0054] Example

[0055] This embodiment prepares a printed product, the substrate of which is kraft paper, and the specific steps are as follows:

[0056] First, polyurethane acrylic resin, epoxy acrylic resin, acrylate, titanium dioxide, wax powder, photosensitizer and thermal stabilizer were mixed and stirred evenly according to the mass percentage in Table 1 using a planetary mixer to obtain a mixed pigment. The mixed pigment was then placed for 6 hours to allow the mixed pigment to be fully wetted. The mixed pigment was then ground in a three-roll mill to obtain a fineness of less than 5 μm to obtain the desired UV white ink.

[0057] Use IGT quantitative instrument to measure 0.2CC of UV white ink that is stirred evenly, add it to the ink roller of Caibang CB225A color display instrument, start the ink distribution for 70 to 90 seconds, use kraft paper as the substrate, roll the ink evenly and then display the sample, test the display sample, set the ink target value to L: 77.66, a: 3.09, b: 1.4, C: 3.39, H: 24.36°, and the color difference value is △E<1 qualified. Measurement settings: measurement mode M1, light source / viewing angle D50 / 2°, △E mode CIE△2000. The results are shown in Table 2. At the same time, the fineness plate, viscosity meter and fluidity meter were used to measure the fineness, viscosity and fluidity of the UV white ink. Finally, the drying experiment was performed to determine its dryness. The measurement results are shown in Table 2.

[0058] Then fold the sample in half and check if there are any cracks. The result shows no cracks.

[0059] Use 3M610 tape to compact the UV white ink printed surface of the sample, pull it up vertically 90 degrees quickly, and observe whether there is white ink. The result shows that there is no ink falling off.

[0060] Finally, UV white ink is printed on the surface of kraft paper by offset printing, and then the predetermined pattern is printed, such as Figure 2 shown.

[0061] Table 1 Raw materials used in the examples

[0062]

[0063] Table 2 UV white ink performance parameters of the embodiment

[0064]

[0065] As can be seen from Table 2, the UV white ink provided by the present invention has excellent printing performance.

[0066] Comparative Example 1

[0067] The titanium dioxide used in Comparative Example 1 is different from that in Example 1, and the rest is the same as that in Example 1. The specific parameters of the titanium dioxide are shown in Table 3, and the properties of the UV white ink are shown in Table 4. There are cracks after folding. The ink falls off when tested with 3M610 tape. Printing a predetermined pattern, such as Figure 3 shown.

[0068] Table 3 Titanium dioxide used in Comparative Example 1

[0069]

[0070] Table 4 UV white ink performance parameters of comparative example 1

[0071]

[0072] Comparative Example 2

[0073] The polyurethane acrylic resin used in Comparative Example 2 is different from that in Example 1, and the rest is the same as that in Example 1. The specific parameters of the polyurethane acrylic resin are shown in Table 5, and the properties of the UV white ink are shown in Table 6. There are cracks after folding. The ink falls off when tested with 3M610 tape. Printing a predetermined pattern, such as Figure 4 shown.

[0074] Table 5 Polyurethane acrylic resin used in Comparative Example 2

[0075] factory model Performance Indicators Lan Ke Road, Dongguan L-6298 Molecular weight: 8000

[0076] Table 6 UV white ink performance parameters of comparative example 2

[0077]

[0078] Comparative Example 3

[0079] Comparative Example 3 uses other resins to replace the polyurethane acrylic resin in the embodiment, and the rest is the same as the embodiment. The specific parameters of the resin are shown in Table 7, and the properties of the prepared UV white ink are shown in Table 8. There are cracks after folding. The ink falls off when tested with 3M610 tape. Printing a predetermined pattern, such as Figure 5 shown.

[0080] Table 7 Resins used in Comparative Example 3

[0081]

[0082]

[0083] Table 8 UV white ink performance parameters of comparative example 3

[0084]

[0085] As can be seen from the above, the UV white ink provided by the present invention has very good hiding power and adhesion, and good printability, while the inks provided by Comparative Examples 1 to 3 have poor performance. Figures 2 to 5 It can be seen that the pattern printed by the UV white ink provided by the present invention is brighter and more exquisite.

[0086] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A UV white ink for special paper, characterized in that: The following raw materials are included in mass percentage: 20-24wt% polyurethane acrylic resin, 8-12wt% epoxy acrylic resin, 8-12wt% acrylate, 45-65wt% titanium dioxide, 0.5-1.5wt% wax powder, 5-7wt% photosensitizer and 0.5-1.5wt% heat stabilizer; Wherein, the molecular weight of the polyurethane acrylic resin is 20,000 to 100,000; The particle size of the titanium dioxide is less than 0.36 μm, the particle size distribution is 0.25 to 0.36 μm, and the density is 0.38 to 0.42 g / cm 2 .

2. The UV white ink according to claim 1, characterized in that: When the substrate is kraft paper, the color value of the UV white ink after printing is L: 77.66, a: 3.09, b: 1.4, C: 3.39, H: 24.36°; Color difference range: color difference value △E<1.

3. The UV white ink according to claim 1, characterized in that: The fineness of the UV white ink is less than 5 μm.

4. The UV white ink according to claim 1, characterized in that: The purity of the titanium dioxide is greater than 99.9%.

5. A method for preparing UV white ink as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Mixing polyurethane acrylic resin, epoxy acrylic resin, acrylate, titanium dioxide, wax powder, photosensitizer and heat stabilizer, stirring evenly and leaving for a predetermined time to allow the mixed pigment to be fully wetted; and S2: Grinding the mixed pigment after being placed for the predetermined time, so that the mixed pigment reaches a predetermined fineness.

6. The preparation method according to claim 5, characterized in that: The predetermined time is greater than 4 hours, and the predetermined fineness is less than 5 μm.

7. A special paper, characterized in that: The surface of the special paper is printed with the UV white ink described in any one of claims 1 to 4.

8. The specialty paper according to claim 7, characterized in that: Printing is done by offset printing.

9. The specialty paper according to claim 7, characterized in that: The substrate of the special paper is kraft paper.

10. A printed product, characterized in that: The special paper according to any one of claims 7 to 9 is printed with text and / or patterns.

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