Preparation method of modified fumed silica for improving glossiness of printing ink

Abstract

The invention provides a preparation method of modified fumed silica for improving glossiness of printing ink, which comprises the following steps: 1) modifying fumed silica by an amino silane coupling agent to obtain amino modified silica; 2) dissolving thioether diamine and dianhydride in a solvent to obtain a mixed solution, adding amino modified silicon dioxide and a dispersing agent, uniformly dispersing, stirring, carrying out temperature control reaction, and carrying out ultrasonic spray drying to obtain polyamide acid modified fumed silica powder; and 3) performing thermal imidization on the polyamide acid modified fumed silica powder in an inert atmosphere to obtain the modified fumed silica. A polyimide thin layer is arranged on the surface of the modified fumed silica, the refractive index of the modified fumed silica is between that of the resin and that of the fumed silica, light scattering at a phase interface is reduced, and the glossiness of the ink is improved; the thin layer can inhibit the agglomeration of the fumed silica and reduce shielding and scattering; through modification, the fumed silica can be uniformly dispersed in the resin ink, and the transparency and glossiness of the ink are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fumed silica, and in particular relates to a method for preparing modified fumed silica for improving the glossiness of ink. Background Art

[0002] In the field of ink technology, glossiness, as a core indicator for evaluating printing quality, directly affects the visual expression and commercial value of the product. High-gloss ink can give printed products excellent mirror effects and color vividness, enhance the visual appeal and market competitiveness of products, and has irreplaceable advantages in fields with strict requirements on visual effects. For example, patent CN101818008B discloses a silver paste ink for scratch-off bills and its preparation method, which is composed of the following components by mass percentage: aluminum powder is 48.72%-51.22%, solvent is 24.65%-27.75%, surface modifier is 0.49%-1.02%, dibutyl phthalate is 0.5%-0.6%, acrylic resin is 19.51%-25.64%, and the total mass is 100%. Scratch-off bills are a common form of ink application in daily life. They use 48.72%-51.22% aluminum powder for printing with a glossiness of up to 74.6, which meets the color rendering requirements and anti-counterfeiting functions. However, they have poor thixotropy and are not anti-settling. They need to be stirred before each use, increasing the workload.

[0003] As an important functional additive in the ink system, fumed silica has shown obvious advantages in improving the rheological properties and anti-settling of inks due to its unique nanostructure and surface characteristics. For example, the preparation method of an environmentally friendly silver scratch-off ink disclosed in patent CN104419251A is composed of the following components by mass percentage: 3% to 15% acrylic resin, 4% to 10% chloroacetic resin, 25% to 40% aluminum silver paste, 6% to 15% fumed silica, 2% to 8% additives, and 25% to 40% solvent. This technology uses fumed silica to improve the rheological properties of the ink, enhance the anti-settling performance of the ink, and reduce the amount of pigments and fillers used.

[0004] However, fumed silica has an adverse effect on the glossiness of inks: first, in order to achieve an ideal anti-settling effect for high-gloss inks that use a large amount of high-density pigments (such as aluminum silver paste and spherical silver powder), a high amount of fumed silica is often required, resulting in a relatively high proportion of inorganic phases in the system and severe light scattering; second, the abundant silanol groups on the surface of fumed silica easily cause particle agglomeration, and the micron-scale aggregates formed block and scatter light; most importantly, the refractive index of fumed silica is significantly different from that of the commonly used resin matrix of inks, resulting in a light scattering effect at the interface. These factors not only limit the optimization of ink glossiness, but also cause a certain degree of waste of pigments and fillers. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a preparation method and application of modified fumed silica for improving the glossiness of ink. The present invention uses thioether diamine and dianhydride as raw materials, forms polyamic acid in situ on the surface of amino-modified silica, and obtains modified fumed silica with a polyimide thin layer on the surface through ultrasonic spray drying and thermal imidization. First, the refractive index of the polyimide thin layer is adjusted between the resin and the fumed silica by adjusting the relative amount of the polyimide raw material and each component, that is, a polyimide refractive index transition layer is formed between the two materials, so that the scattering of light at the interface is reduced, thereby improving the glossiness of the ink. Secondly, the steric hindrance effect of the polyimide thin layer will inhibit the formation of micron-level agglomerates of fumed silica, reduce the blocking and scattering of light, and improve the glossiness of the ink. Finally, the polyimide layer reduces the polarity of the fumed silica, so that it can be more evenly dispersed in the ink, improving the transparency and glossiness of the ink.

[0006] In order to achieve the above purpose, the following technical solutions are adopted:

[0007] A method for preparing modified fumed silica for improving the glossiness of ink comprises the following steps:

[0008] 1) Aminosilane coupling agent modifies fumed silica to obtain amino-modified silica;

[0009] 2) dissolving thioether diamine and dianhydride in a solvent to obtain a mixed solution, adding amino-modified silica and a dispersant to disperse uniformly, stirring, controlling the temperature to react, and ultrasonically spray drying to obtain polyamic acid-modified fumed silica powder;

[0010] 3) Under an inert atmosphere, the polyamic acid-modified fumed silica powder is thermally imidized to obtain modified fumed silica.

[0011] In step 1), the specific surface area of ​​the fumed silica is 200-400m 2 / g. The aminosilane coupling agent is selected from p-aminophenyltrimethoxysilane, p-aminophenyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, or a combination of two or more thereof.

[0012] The modification process of fumed silica is as follows: dispersing fumed silica in an aminosilane coupling agent solution, heating it to a reflux state for reaction, and obtaining amino-modified silica. The concentration of the aminosilane coupling agent solution is 3-5wt%, and the solvent of the aminosilane coupling agent solution is selected from one or a combination of toluene or benzene. The dispersion is ultrasonic dispersion for 30-40 minutes under the conditions of an ultrasonic power of 200-400W and a frequency of 30-50kHz. The reaction time is 12-24h. The mass volume ratio of the fumed silica and the aminosilane coupling agent solution is 5-10g / 100mL. After the reaction is completed, washing and drying steps are also included. The washing is washing with alcohol and water alternately for 1-3 times. The drying is drying at 60-80°C to constant weight.

[0013] In step 2), the mass ratio of the dianhydride to the sulfide diamine is 28-33:25. The mass of the dianhydride and the sulfide diamine accounts for 1-2wt% in the mixed solution. The mass ratio of the amino-modified silica, the dispersant, and the mixed solution is 5-8:1-1.5:100. The sulfide diamine is selected from one or a combination of two or more of 4,4'-diaminodiphenyl sulfide, 4,4'-dithiodiphenylamine, 2,2'-diaminodiphenyl sulfide, and 2,2'-diaminodiphenyl disulfide. The dianhydride is selected from one or a combination of two or more of 3,3'4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, and ethylenediaminetetraacetic dianhydride, preferably ethylenediaminetetraacetic dianhydride. The solvent is selected from one or a combination of two or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide. The dispersion is ultrasonic dispersion for 1-2 hours at a power of 200-500W and a frequency of 20-40kHz. The stirring speed is 500-800r / min. The temperature control reaction is to control the temperature at 40-60°C and react for 5-8h. The ultrasonic spray drying conditions are: inlet temperature 180-200°C, outlet temperature 80-90°C, fan frequency 80-100Hz, feed rate 150-200mL / h, and ultrasonic dispersion frequency 30-40kHz. The dispersant is selected from one or a combination of two or more of polyvinyl pyrrolidone, oleic acid, stearic acid, sodium stearate, and zinc stearate.

[0014] In step 3), the thermal imidization reaction is carried out by heating from room temperature to 300-350° C. and maintaining for 1-3 hours, with a heating rate of 3-5° C. / min.

[0015] A scratch-off ink with improved glossiness comprises the following raw materials in parts by weight: 15-25 parts of thermoplastic acrylic resin, 0.3-0.5 parts of etherified melamine formaldehyde resin, 15-30 parts of aluminum silver powder, 10-15 parts of modified fumed silica for improving the glossiness of the ink, 0.1-0.3 parts of a dispersant, and 20-40 parts of a solvent.

[0016] The etherified melamine formaldehyde resin is selected from one or a combination of methyl etherified melamine formaldehyde resin and butyl etherified melamine formaldehyde resin. The inventors found that an appropriate amount of etherified melamine formaldehyde resin can cooperate with the modified fumed silica for improving the glossiness of the ink to improve the storage stability of the ink. It is speculated that the hydroxymethyl in the etherified melamine formaldehyde resin molecule can form hydrogen bonds with the remaining silanol groups on the surface of the fumed silica, and can also form hydrogen bonds with the imide bonds on the polyimide, thereby improving the stability and complexity of the three-dimensional network structure formed between the particles, limiting the thermal motion of the inorganic particles in the ink, reducing the risk of aggregation, and inhibiting precipitation.

[0017] The aluminum silver powder is a flaky non-leafing aluminum silver powder with a D50 particle size of 8-20 μm.

[0018] The solvent is selected from one or a combination of two or more of methyl acetate, ethyl acetate, diethyl carbonate, propyl acetate and butyl acetate.

[0019] The weight average molecular weight of the thermoplastic acrylic resin is 80,000-150,000.

[0020] The dispersant is selected from one or a combination of two or more of sodium stearate, aluminum stearate, calcium stearate, sodium oleate and sodium laurate.

[0021] The present invention also provides a method for preparing the above-mentioned scratch-off ink with improved gloss, comprising the following steps:

[0022] The etherified melamine formaldehyde resin and the thermoplastic acrylic resin are dissolved in a solvent, and aluminum silver powder, the modified fumed silica for improving the glossiness of the ink and a dispersant are added, mixed evenly, ground and discharged to obtain the scratch-off ink with improved glossiness.

[0023] The grinding is performed to a fineness of 10-30 μm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The invention uses thioether diamine and dianhydride as raw materials, forms polyamic acid in situ on the surface of amino-modified silica, and obtains modified fumed silica with a polyimide thin layer on the surface through ultrasonic spray drying and thermal imidization; the refractive index of the thin layer is between that of the resin and the fumed silica, that is, a polyimide refractive index transition layer is formed between the two materials, so that the scattering of light at the interface is reduced, thereby improving the glossiness of the ink; in addition, the steric hindrance effect of the polyimide thin layer inhibits the formation of micron-level agglomerates of the fumed silica, reduces the shielding and scattering of light, and improves the glossiness of the ink; finally, the polyimide layer reduces the polarity of the fumed silica, so that it can be more evenly dispersed in the resin ink, further improving the transparency and glossiness of the ink.

[0026] The scraped-off ink with improved glossiness of the present invention has high glossiness, can completely block light penetration, and effectively prevent underlying information from being viewed through perspective or by side light. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, the "parts" described in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0028] The acrylic resin is DSM B838 with a weight average molecular weight of 85,000.

[0029] The specific surface area of ​​fumed silica is 260m 2 / g, from Shandong Hongruitong New Material Technology Co., Ltd.

[0030] Non-leafing flake aluminum silver powder CYH-10, with a D50 particle size of 15-17 μm, was purchased from Hunan Jinhao New Materials Technology Co., Ltd.

[0031] Non-leafing flake aluminum silver powder CYH-15, with a D50 particle size of 9-11 μm, was purchased from Hunan Jinhao New Materials Technology Co., Ltd.

[0032] Methylated melamine formaldehyde resin was purchased from Huibaixin (Shandong) New Materials Co., Ltd., brand HBX-9303.

[0033] Example 1

[0034] 1) Adding fumed silica at a mass volume ratio of 10 g / 100 mL to a 5 wt% p-aminophenyltrimethoxysilane solution (solvent: benzene), dispersing by ultrasonication for 40 min at an ultrasonic power of 200 W and a frequency of 30 kHz, heating to reflux for reaction for 12 h, washing with ethanol and water alternately for 3 times, and drying at 60° C. to constant weight to obtain amino-modified silica;

[0035] 2) 2 parts by mass of a raw material consisting of ethylenediaminetetraacetic acid dianhydride and 4,4'-dithiodiphenylamine in a mass ratio of 33:25 were dissolved in 98 parts by mass of dimethylformamide to obtain a mixed solution, 8 parts by mass of amino-modified silica and 1.5 parts by mass of polyvinyl pyrrolidone were added to 100 parts by mass of the mixed solution, and the mixture was uniformly dispersed by ultrasonication for 1.5 hours at a power of 300 W and a frequency of 20 kHz, and then stirred at a speed of 800 r / min and a temperature of 60° C. for 8 hours, and ultrasonically spray-dried at an inlet temperature of 200° C., an outlet temperature of 90° C., a fan frequency of 100 Hz, a feed rate of 150 mL / h, and an ultrasonic dispersion frequency of 40 kHz to obtain a polyamic acid-modified fumed silica powder;

[0036] 3) In a nitrogen atmosphere, the polyamic acid-modified fumed silica powder was heated from room temperature to 350° C. at a heating rate of 5° C. / min and maintained for 3 h for thermal imidization to obtain modified fumed silica.

[0037] 4) 0.5 parts by mass of methylated melamine formaldehyde resin HBX-9303 and 15 parts by mass of thermoplastic acrylic resin are dissolved in 40 parts by mass of ethyl acetate, 30 parts by mass of aluminum silver powder CYH-10, 15 parts by mass of modified fumed silica obtained in step 3) and 0.3 parts by mass of aluminum stearate are added, mixed evenly, ground to a fineness of 20 μm, and discharged to obtain a scratch-off ink with improved glossiness.

[0038] Example 2

[0039] The rest is the same as Example 1, except that in step 2), the mass ratio of ethylenediaminetetraacetic dianhydride to 4,4'-dithiodiphenylamine is 28:25.

[0040] Example 3

[0041] The rest is the same as Example 1, except that in step 2), 4,4'-diaminodiphenyl sulfide is used instead of 4,4'-dithiodiphenylamine with an equal mass.

[0042] Example 4

[0043] The rest is the same as Example 1, except that in step 2), ethylenediaminetetraacetic acid dianhydride is replaced by an equal mass of pyromellitic acid dianhydride.

[0044] Example 5

[0045] The rest is the same as Example 1, except that in step 2), the amount of amino-modified silica used is 5 parts by mass.

[0046] Example 6

[0047] The rest is the same as Example 1, except that in step 4), the amount of the modified fumed silica prepared in step 3) is 10 parts by mass.

[0048] Example 7

[0049] The rest is the same as Example 1, except that in step 4), the amount of etherified melamine formaldehyde resin HBX-9303 used is 0.3 parts by mass.

[0050] Example 8

[0051] 1) Dispersing the fumed silica in a 3 wt % p-aminophenyltrimethoxysilane solution (solvent: benzene) at a mass volume ratio of 10 g / 100 mL under ultrasonic conditions of 200 W of ultrasonic power and 30 kHz of frequency for 40 min, heating to reflux state for reaction for 12 h, washing with ethanol and water alternately for 3 times, and drying at 60° C. to constant weight to obtain amino-modified silica;

[0052] 2) 1 part by mass of a raw material consisting of ethylenediaminetetraacetic acid dianhydride and 4,4'-dithiodiphenylamine in a mass ratio of 33:25 was dissolved in 99 parts by mass of dimethylformamide to obtain a mixed solution, 8 parts by mass of amino-modified silica and 1 part by mass of polyvinyl pyrrolidone were added to 100 parts by mass of the mixed solution, and the mixture was uniformly dispersed by ultrasonication for 1.5 hours at a power of 300 W and a frequency of 20 kHz, and then stirred at a speed of 800 r / min and a temperature of 60° C. for 8 hours, and ultrasonically spray-dried at an inlet temperature of 200° C., an outlet temperature of 90° C., a fan frequency of 80 Hz, a feed rate of 200 mL / h, and an ultrasonic dispersion frequency of 40 kHz to obtain a polyamic acid modified powder;

[0053] 3) In a nitrogen atmosphere, the polyamic acid modified powder is thermally imidized by heating from room temperature to 350° C. at a heating rate of 5° C. / min and maintaining the temperature for 3 h to obtain modified fumed silica.

[0054] 4) 0.5 parts by mass of methylated melamine formaldehyde resin HBX-9303 and 25 parts by mass of thermoplastic acrylic resin are dissolved in 40 parts by mass of ethyl acetate, 30 parts by mass of aluminum silver powder CYH-10, 15 parts by mass of modified fumed silica for improving the glossiness of the ink, and 0.3 parts by mass of aluminum stearate are added, mixed evenly, ground to a fineness of 20 μm, and discharged to obtain a scratch-off ink with improved glossiness.

[0055] Comparative Example 1

[0056] The rest is the same as Example 1, except that in step 2), an equal mass of p-phenylenediamine is used to replace 4,4'-dithiodiphenylamine.

[0057] Comparative Example 2

[0058] The rest is the same as Example 1, except that in step 4), methyl etherified melamine formaldehyde resin HBX-9303 is not added.

[0059] Comparative Example 3

[0060] The rest is the same as Example 1, except that steps 1) to 3) are omitted, and in step 4), the fumed silica is not modified;

[0061] 0.5 parts by mass of methylated melamine formaldehyde resin HBX-9303 and 15 parts by mass of thermoplastic acrylic resin are dissolved in 40 parts by mass of ethyl acetate, 30 parts by mass of aluminum silver powder CYH-10, 15 parts by mass of fumed silica and 0.3 parts by mass of aluminum stearate are added, mixed evenly, ground to a fineness of 20 μm, and discharged to obtain a scratch-off ink with improved glossiness.

[0062] The inks prepared in the above examples and comparative examples were subjected to the following performance tests:

[0063] Thixotropic index (TI value): TI value refers to the ratio of the viscosity value when the BH type rotational viscometer is rotated 2 times to the viscosity value when it is rotated 20 times at 25°C, that is, the value indicating the viscosity value when the BH type rotational viscometer is rotated 2 times / the viscosity value when the BH type rotational viscometer is rotated 20 times.

[0064] Glossiness: On a glass with a format of 20×20cm, the prepared ink was used for proofing, using an IGT-F1 printability tester, with a pressure of 150N, a screen number of 200dpi, a printing speed of 0.3m / s, printing twice, and then baking at 80℃ for 2.5h to form a film. A 60° mirror gloss meter (3nh multi-angle precision gloss meter NHG268, Sannh Company) was used to test the glossiness of the high-gloss ink.

[0065] Storage stability: Place the ink in a constant temperature box at 40°C, re-test the gloss after 30 days, and calculate the gloss decay rate before and after storage.

[0066] Table 1 Performance test results

[0067]

[0068]

[0069] It can be seen from Table 1 that the modified fumed silica prepared by the present invention has the function of improving the glossiness of the ink, and the etherified melamine formaldehyde resin has the effect of synergizing with the modified fumed silica of the present invention to improve the storage stability of the ink. After being stored for a period of time, the aluminum silver powder does not precipitate and is still evenly distributed in the ink. The glossiness of the printed product is slightly attenuated, and the light reflection is almost unaffected.

[0070] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing modified fumed silica for improving the glossiness of ink, characterized in that: The steps include: 1) Aminosilane coupling agent modifies fumed silica to obtain amino-modified silica; 2) dissolving thioether diamine and dianhydride in a solvent to obtain a mixed solution, adding amino-modified silica and a dispersant to disperse uniformly, stirring, controlling the temperature to react, and ultrasonically spray drying to obtain polyamic acid-modified fumed silica powder; 3) Under an inert atmosphere, the polyamic acid-modified fumed silica powder is thermally imidized to obtain modified fumed silica.

2. The method for preparing modified fumed silica for improving the glossiness of ink according to claim 1, characterized in that: In step 1), the specific surface area of ​​the fumed silica is 200-400m 2 / g; the aminosilane coupling agent is selected from p-aminophenyltrimethoxysilane, p-aminophenyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, or a combination of two or more thereof.

3. The method for preparing modified fumed silica for improving the glossiness of ink according to claim 1, characterized in that: In step 2), the mass ratio of the dianhydride to the sulfide diamine is 28-33:25; the total mass of the dianhydride and the sulfide diamine accounts for 1-2wt% of the mixed solution; the mass ratio of the amino-modified silica, the dispersant, and the mixed solution is 5-8:1-1.5:

100.

4. The method for preparing modified fumed silica for improving the glossiness of ink according to claim 1, characterized in that: In step 2), the sulfide diamine is selected from one or a combination of two or more of 4,4'-diaminodiphenyl sulfide, 4,4'-dithiodiphenylamine, 2,2'-diaminodiphenyl sulfide, and 2,2'-diaminodiphenyl disulfide; the dianhydride is selected from one or a combination of two or more of 3,3'4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, and ethylenediaminetetraacetic dianhydride.

5. The method for preparing modified fumed silica for improving the glossiness of ink according to claim 1, characterized in that: In step 2), the dispersion is carried out by ultrasonic dispersion at a power of 200-500 W and a frequency of 20-40 kHz for 1-2 h; the stirring speed is 500-800 r / min; the temperature-controlled reaction is carried out by controlling the temperature at 40-60° C. and reacting for 5-8 h; and / or In step 2), the ultrasonic spray drying conditions are: inlet temperature 180-200°C, outlet temperature 80-90°C, fan frequency 80-100Hz, feed rate 150-200mL / h, and ultrasonic dispersion frequency 30-40kHz.

6. The method for preparing modified fumed silica for improving ink glossiness according to claim 1, characterized in that: In step 3), the thermal imidization reaction is carried out by heating from room temperature to 300-350° C. and maintaining for 1-3 hours.

7. The method for preparing modified fumed silica for improving the glossiness of ink according to claim 6, characterized in that: The heating rate is 3-5℃ / min.

8. A scratch-off ink with improved gloss, characterized in that: The invention comprises the following raw materials in parts by weight: 15-25 parts of thermoplastic acrylic resin, 0.3-0.5 parts of etherified melamine formaldehyde resin, 15-30 parts of aluminum silver powder, 10-15 parts of modified gas-phase silica for improving the glossiness of ink according to any one of claims 1-7, 0.1-0.3 parts of dispersant, and 20-40 parts of solvent.

9. The scratch-off ink with improved glossiness according to claim 8, characterized in that: The etherified melamine formaldehyde resin is selected from one or a combination of methyl etherified melamine formaldehyde resin and butyl etherified melamine formaldehyde resin; the aluminum silver powder is flaky non-leafing aluminum silver powder with a D50 particle size of 8-20 μm; and the weight average molecular weight of the thermoplastic acrylic resin is 80,000-150,000.

10. The method for preparing the scratch-off ink with improved glossiness according to claim 8 or 9, characterized in that: The steps include: Etherified melamine formaldehyde resin and thermoplastic acrylic resin are dissolved in a solvent, and aluminum silver powder, modified fumed silica for improving the glossiness of the ink and a dispersant are added, mixed evenly, ground and discharged to obtain a scratch-off ink with improved glossiness.

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