Preparation method and application of high anti-skid and anti-stick emulsion for water-based pre-printing varnish

Abstract

The present invention relates to the technical field of printing coatings, specifically to a preparation method and application of a highly anti-skid and anti-stick emulsion for water-based pre-printed varnish. The present invention pre-disperses silica powder in a synthetic resin solution through high-speed dispersion, and then coats the silica powder in the core layer of a core-shell emulsion through seed emulsion polymerization, so that the emulsion does not affect the overall high anti-skid performance while avoiding the hot viscosity of the system in a high-temperature environment. It has good heat resistance and anti-adhesion performance, and its storage stability and performance stability are better than those of traditional physical mixing of silica and emulsion. The outer layer of the emulsion contains ketone carbonyl groups, which self-crosslink with the hydrazide groups of oxalic acid dihydrazide added later during the coating and natural drying process, further improving the strength of the emulsion after film formation, and improving the temperature resistance and wear resistance of the emulsion while ensuring high anti-skid performance.

Description

Technical Field

[0001] The invention relates to the technical field of printing coatings, in particular to a preparation method and application of a high-anti-slip and anti-stick emulsion for water-based pre-printing varnish. Background Art

[0002] Water-based varnishes are widely used in the coating printing industry due to their water-based solvent, environmental friendliness, and ease of use. Pre-print water-based varnishes account for over half of all water-based varnishes used. Due to the process requirements of pre-printed cardboard lines, varnishes must possess excellent heat resistance and anti-stick properties. However, under normal conditions, these heat resistance and anti-stick properties conflict with their anti-slip properties. Therefore, achieving a balance of high heat resistance, anti-stick properties, and high anti-slip properties in pre-print water-based varnishes is difficult.

[0003] Chinese patent CN201811129167.2 discloses a monomer mixture, a water-based anti-slip pre-print emulsion using the same, and a preparation method thereof. The invention uses pentaerythritol tetraacrylate as a cross-linking monomer, which is polymerized with styrene, isooctyl acrylate, and butyl acrylate to form a spatial structure, greatly improving the heat resistance and wear resistance of the water-based anti-slip emulsion. However, the cost of the pentaerythritol tetraacrylate cross-linking monomer is relatively high, and its use significantly affects the stability of the emulsion performance, easily resulting in a high gel fraction of the synthesized emulsion, limiting its practical industrial application. Patent CN 201310182900.8 discloses a water-based pre-print emulsion and a preparation method thereof. Using a heat-resistant pure acrylic emulsion, styrene maleic anhydride resin liquid, styrene, methyl methacrylate, butyl acrylate, etc., a water-based pre-print emulsion with heat resistance and high gloss properties is synthesized. However, to ensure high heat resistance, the pre-print emulsion prepared in this invention uses a large amount of hard resin and monomers, resulting in a hard and brittle varnish film, making it difficult to achieve high anti-slip properties. Summary of the Invention

[0004] The present invention aims to solve the defects in the prior art and aims to provide a method for preparing and applying a highly anti-slip and anti-stick emulsion for water-based pre-printing varnish.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a highly anti-slip and anti-stick emulsion for water-based pre-printing varnish, the method comprising the following steps:

[0007] S1: uniformly disperse silica powder, aqueous acrylic acid dispersion resin solution, defoamer, and deionized water to obtain S1 powder dispersion;

[0008] S2: adding the entire S1 fine powder dispersion, a portion of the total amount of the mixed core layer reaction monomers (preferably 10% of the total amount of the mixed core layer reaction monomers), and a portion of the emulsifier (preferably one-third of the total amount of the emulsifier) ​​to a reactor, stirring at 30-50° C. for 10-40 minutes (preferably at 40° C. for 20 minutes), stirring and heating, and when the temperature in the reactor reaches 75-85° C., adding a portion of the initiator (preferably one-third of the total amount of the initiator), maintaining the reaction at 75-85° C. for 0.5-2 hours (preferably at 80° C. for 1 hour);

[0009] S3: simultaneously adding the remaining mixed core layer reaction monomers, a portion of the emulsifier (preferably one-third of the total amount of the emulsifier), and a portion of the initiator (preferably one-third of the total amount of the initiator) to the reactor (preferably, the addition is completed within 1.5 hours), controlling the system temperature at 75-85° C. during the addition. After the addition is completed, the reaction is kept at 75-85° C. for 0.5-2 hours (preferably at 80° C. for 1 hour);

[0010] S4: adding the mixed shell reaction monomers, the remaining emulsifier and the remaining initiator dropwise to the reaction kettle (preferably, the addition is completed within 1.5 hours), controlling the system temperature at 75-85° C. during the addition, and then reacting at 75-85° C. for 0.5-2 hours (preferably at 80° C. for 1 hour);

[0011] S5: cooling to 30-50° C., adding oxalic acid dihydrazide, stirring for 20-60 minutes (preferably: cooling to 40° C., adding oxalic acid dihydrazide, stirring at 40° C. for 30 minutes), and cooling to room temperature to obtain a highly anti-slip and anti-stick emulsion for water-based pre-printing varnish;

[0012] In S2, the mixed core layer reaction monomers are compound A and compound B: compound A is styrene and / or methyl methacrylate, and compound B is butyl acrylate and / or isooctyl acrylate;

[0013] In the above S4, the mixed shell reaction monomers include butyl acrylate and / or isooctyl acrylate, divinylbenzene, and diacetone acrylamide.

[0014] Preferably, the emulsifier comprises a mixed emulsifier of anionic emulsifier and nonionic emulsifier, the anionic emulsifier is sodium dodecyl sulfonate or sodium dodecyl diphenyl ether disulfonate, the nonionic emulsifier is fatty alcohol polyoxyethylene ether, and the amount of the emulsifier is 1%-2% (preferably 1.125%-1.95%) of the total raw material mass, wherein the mass ratio of the anionic emulsifier to the nonionic emulsifier is 1:(1.6-2);

[0015] The total raw material mass refers to the mass of all substances described in S1-S5.

[0016] Preferably, the initiator is an aqueous solution of ammonium persulfate, which accounts for (5.25-11.55)% of the total raw material mass;

[0017] Preferably, in S1, the raw materials used are as follows: 1%-2% by mass of silica powder (preferably hydrophilic silica with a particle size of less than 0.5 μm, such as Degussa Silica A200), 40%-60% of aqueous acrylate resin solution (preferably BASF Joncryl 678 aqueous resin with a solid content of 25%), and 0.1% of defoamer (preferably silicone defoamer, such as TEGO Airex901w).

[0018] Preferably, the total amount of compound A and compound B accounts for 10.5-16% of the total raw material mass; the mass ratio of compound A to compound B is (15-20):1;

[0019] Preferably, in said S4, the mixed shell reaction monomers include butyl acrylate and / or isooctyl acrylate accounting for 15-20% of the total raw material mass, divinylbenzene accounting for 0.15%-0.2% of the total raw material mass, and diacetone acrylamide accounting for 0.5%-1% of the total raw material mass;

[0020] Preferably, in S5, the amount of oxalic acid dihydrazide used accounts for 0.5%-1% of the total raw material mass.

[0021] The present invention also provides the use of the highly anti-skid and anti-stick emulsion of water-based pre-printing varnish obtained by the above-mentioned preparation method in the preparation of water-based pre-printing varnish.

[0022] Preferably, the water-based pre-printed varnish comprises, by weight, 78-82 parts of a water-based pre-printed varnish high anti-slip and anti-stick emulsion obtained by any of the preparation methods described above, 18-22 parts of an acrylic resin aqueous solution, 7-9 parts of an aqueous wax emulsion, 1-3 parts of a film-forming aid, 0.1-0.8 parts of a wetting agent, 0.05-0.2 parts of a defoaming agent, and 3-8 parts of water.

[0023] More preferably, the water-based pre-printed varnish comprises, by weight, 80 parts of a water-based pre-printed varnish high anti-slip and anti-stick emulsion obtained by any of the preparation methods described above, 20 parts of an acrylic resin aqueous solution, 8.5 parts of an aqueous wax emulsion, 2 parts of a film-forming aid, 0.5 parts of a wetting agent, 0.1 parts of a defoaming agent, and 5.4 parts of water.

[0024] Preferably, the solid content of the acrylic resin aqueous solution is 30±5%, and the film-forming aid is ethylene glycol ethyl ether. The aqueous wax emulsion is composed of 8 parts of Longhai Chemical 2541 aqueous wax emulsion and 0.5 parts of Longhai Chemical 255 aqueous wax emulsion.

[0025] Compared with the prior art, the technical solution of the present invention has the following advantages and beneficial effects:

[0026] 1. The water-based pre-print varnish emulsion prepared by the present invention adopts a core-shell structure. Silica powder is well pre-dispersed in a synthetic resin liquid through high-speed dispersion. The silica powder is then coated on the core layer of the core-shell emulsion through seed emulsion polymerization. This allows the emulsion to avoid hot stickiness in high-temperature environments without affecting the overall high anti-slip performance, and has good heat resistance and anti-blocking properties. Compared with traditional physical mixing of silica and emulsion, its storage stability and performance stability are better.

[0027] 2. The emulsion prepared by the technical solution of the present invention has a core-shell structure with a hard inner layer and a soft outer layer. The core layer is relatively hard, which ensures the temperature resistance of the emulsion; the outer layer cross-linked structure is relatively soft and has good strength, providing the emulsion with good film-forming properties and high anti-slip properties;

[0028] 3. The outer layer of the emulsion prepared by the technical solution of the present invention contains ketone carbonyl groups, which undergo self-crosslinking with the hydrazide groups of oxalic acid dihydrazide added later during the coating and natural drying process, further improving the strength of the emulsion after film formation, and improving the temperature resistance and wear resistance of the emulsion while ensuring high anti-slip performance.

[0029] Conventional water-based acrylic emulsion resins all have the drawbacks of being sticky when hot and brittle when cold. This makes it difficult to achieve a high anti-slip angle at relatively low temperatures for water-based varnishes prepared from them. To ensure heat resistance, the anti-slip performance of emulsions used in pre-printing processes is even more difficult to improve. The raw materials used in the present invention are commonly used industrial raw materials, which are relatively low in cost and readily available. The prepared emulsion is applied to water-based pre-print varnishes, ensuring high anti-slip performance (anti-slip angle on inclined surfaces >28 degrees) while also exhibiting good temperature resistance and anti-blocking properties, thus having high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a storage stability chart of the water-based pre-printing varnish prepared in Examples 1-4 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0031] The applicant will now explain in detail the technical solutions and effects of the present invention in conjunction with specific embodiments.

[0032] The aqueous pre-print varnish emulsion prepared by the present invention is prepared by the following scheme. It should be understood that the following examples are only examples and the present invention is not limited to these examples.

[0033] In the following examples, "parts" refer to "parts by weight", and each "part" refers to 100 g.

[0034] Example 1 A highly anti-slip and anti-stick emulsion for water-based pre-printing varnish is prepared according to the following steps:

[0035] S1: Add 60 parts of Joncryl 678 aqueous acrylic resin solution with a solid content of 25%, 2 parts of silica powder A200, 4.875 parts of deionized water, and 0.1 part of defoamer TEGO Airex901w to a high-speed stirring kettle. Start the high-speed stirrer and adjust the speed to 2000 rpm. After stirring and dispersing for 20 minutes, discharge the material to obtain S1 powder dispersion.

[0036] S2: Add all the fine powder dispersion obtained in S1, 1 part of styrene, 0.05 part of isooctyl acrylate, 0.125 part of sodium lauryl sulfonate, and 0.25 part of fatty alcohol polyoxyethylene ether to a reactor, heat to 40°C, mix and stir for 20 minutes, continue stirring and heat to 80°C, then add an aqueous solution of ammonium persulfate (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) to initiate the reaction, and then keep the reaction at 80°C for 1 hour;

[0037] S3: 9 parts of styrene and 0.45 parts of isooctyl acrylate were slowly added dropwise to the above-mentioned reaction kettle. At the same time, 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and an aqueous solution of ammonium persulfate (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) were added dropwise thereto. During the addition, the system temperature was maintained at about 80° C. and the addition rate was controlled. The addition was completed in about 1.5 hours. After the addition was completed, the reaction was kept at 80° C. for 1 hour.

[0038] S4: 15 parts of isooctyl acrylate, 0.15 parts of divinylbenzene, and 0.5 parts of diacetone acrylamide are slowly added dropwise to the above-mentioned reaction kettle, and 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and ammonium persulfate aqueous solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) are added dropwise thereto. During the addition, the system temperature is maintained at about 80° C. and the addition speed is controlled. The addition is completed in about 1.5 hours. After the addition is completed, the reaction is kept at 80° C. for 1 hour.

[0039] S5: Cool the reactor to 40° C., add 0.5 parts of oxalic acid dihydrazide thereto, disperse and stir at 40° C. for 30 minutes, cool to room temperature (25° C., the same below), discharge the material and take out the high anti-slip and anti-stick emulsion for water-based pre-printing varnish of Example 1 (abbreviated as: pre-printing emulsion).

[0040] Example 2 A highly anti-slip and anti-stick emulsion for water-based pre-printing varnish was prepared according to the following steps:

[0041] S1: In a high-speed stirring kettle, add 40 parts of Joncryl 678 aqueous acrylic resin solution with a solid content of 25%, 1 part of silica powder A200, 7.35 parts of deionized water, and 0.1 part of defoamer TEGO Airex901w. Start the high-speed stirrer and adjust the speed to 2000 rpm. After stirring and dispersing for 20 minutes, discharge the material to obtain S1 powder dispersion.

[0042] S2: Add all the fine powder dispersion obtained in S1, 1.5 parts of styrene, 0.1 parts of isooctyl acrylate, 0.25 parts of sodium lauryl sulfonate, and 0.4 parts of fatty alcohol polyoxyethylene ether to a reactor, heat to 40°C, mix and stir for 20 minutes, continue stirring and heat to 80°C, then add an aqueous solution of ammonium persulfate (prepared by dissolving 0.3 parts of ammonium persulfate in 3.5 parts of deionized water) to initiate the reaction, and then keep the reaction at 80°C for 1 hour;

[0043] S3: 13.5 parts of styrene and 0.9 parts of isooctyl acrylate were slowly added dropwise to the above-mentioned reaction kettle, and 0.25 parts of sodium lauryl sulfate, 0.4 parts of fatty alcohol polyoxyethylene ether, and ammonium persulfate aqueous solution (prepared by dissolving 0.3 parts of ammonium persulfate in 3.5 parts of deionized water) were added dropwise thereto. During the addition, the system temperature was maintained at about 80°C and the addition speed was controlled. The addition was completed in about 1.5 hours. After the addition was completed, the reaction was kept at 80°C for 1 hour.

[0044] S4: 20 parts of isooctyl acrylate, 0.2 parts of divinylbenzene, and 1 part of diacetone acrylamide are slowly added dropwise to the above-mentioned reaction kettle, and 0.25 parts of sodium lauryl sulfate, 0.4 parts of fatty alcohol polyoxyethylene ether, and ammonium persulfate aqueous solution (prepared by dissolving 0.3 parts of ammonium persulfate in 3.5 parts of deionized water) are added dropwise. During the addition, the system temperature is maintained at about 80° C. and the addition speed is controlled. The addition is completed in about 1.5 hours. After the addition is completed, the reaction is kept at 80° C. for 1 hour.

[0045] S5: Cool the reactor to 40° C., add 1 part of oxalic acid dihydrazide, disperse and stir at 40° C. for 30 minutes, cool to room temperature, discharge the material and obtain the highly anti-slip and anti-stick emulsion for water-based pre-printing varnish of Example 2 (abbreviated as: pre-printing emulsion).

[0046] Example 3 A highly anti-slip and anti-stick emulsion for water-based pre-printing varnish was prepared according to the following steps:

[0047] S1: Add 60 parts of Joncryl 678 aqueous acrylic resin solution with a solid content of 25%, 2 parts of silica powder A200, 4.875 parts of deionized water, and 0.1 part of defoamer TEGO Airex901w to a high-speed stirring kettle. Start the high-speed stirrer and adjust the speed to 2000 rpm. After stirring and dispersing for 20 minutes, discharge the material to obtain S1 powder dispersion.

[0048] S2: Add all the fine powder dispersion obtained by S1, 1 part of methyl methacrylate, 0.05 part of butyl acrylate, 0.125 part of sodium lauryl sulfate, and 0.25 part of fatty alcohol polyoxyethylene ether to the reactor, heat to 40°C and stir for 20 minutes, then continue stirring and heat to 80°C, then add ammonium persulfate aqueous solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) to initiate the reaction, and then keep the reaction at 80°C for 1 hour;

[0049] S3: 9 parts of methyl methacrylate and 0.45 parts of butyl acrylate were slowly added dropwise to the above-mentioned reaction kettle, and 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and ammonium persulfate aqueous solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) were added dropwise thereto. During the addition, the system temperature was maintained at about 80° C. and the addition rate was controlled. The addition was completed in about 1.5 hours. After the addition was completed, the reaction was kept at 80° C. for 1 hour.

[0050] S4: 15 parts of butyl acrylate, 0.15 parts of divinylbenzene, and 0.5 parts of diacetone acrylamide are slowly added dropwise to the above-mentioned reaction kettle, and 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and ammonium persulfate aqueous solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) are added dropwise thereto. During the addition, the system temperature is maintained at about 80° C. and the addition speed is controlled. The addition is completed in about 1.5 hours. After the addition is completed, the reaction is kept at 80° C. for 1 hour.

[0051] S5: Cool the reactor to 40° C., add 0.5 parts of oxalic acid dihydrazide, disperse and stir at 40° C. for 30 minutes, cool to room temperature, discharge the material and obtain the highly anti-skid and anti-stick emulsion for pre-printing varnish of Example 3 (abbreviated as: pre-printing emulsion).

[0052] Example 4 A highly anti-slip and anti-stick emulsion for water-based pre-printing varnish was prepared according to the following steps:

[0053] S1: Add 60 parts of Joncryl 678 aqueous acrylic resin solution with a solid content of 25%, 2 parts of silica powder A200, 4.875 parts of deionized water, and 0.1 part of defoamer TEGO Airex901w to a high-speed stirring kettle. Start the high-speed stirrer and adjust the speed to 2000 rpm. After stirring and dispersing for 20 minutes, discharge the material to obtain S1 powder dispersion.

[0054] S2: Add all the fine powder dispersion obtained in S1, 0.5 parts of styrene, 0.5 parts of methyl methacrylate, 0.025 parts of butyl acrylate, 0.025 parts of isooctyl acrylate, 0.125 parts of sodium lauryl sulfate, and 0.25 parts of fatty alcohol polyoxyethylene ether to a reactor, heat to 40°C, mix and stir for 20 minutes, continue stirring and heat to 80°C, then add an aqueous solution of ammonium persulfate (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) to initiate the reaction, and then keep the reaction at 80°C for 1 hour;

[0055] S3: 4.5 parts of styrene, 4.5 parts of methyl methacrylate, 0.22 parts of butyl acrylate, and 0.23 parts of isooctyl acrylate are slowly added dropwise to the above-mentioned reaction kettle, and 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and an aqueous ammonium persulfate solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) are added dropwise thereto. During the addition, the system temperature is maintained at about 80° C. and the addition speed is controlled. The addition is completed in about 1.5 hours. After the addition is completed, the reaction is kept at 80° C. for 1 hour.

[0056] S4: 7 parts of butyl acrylate, 8 parts of isooctyl acrylate, 0.15 parts of divinylbenzene, and 0.5 parts of diacetone acrylamide are slowly added dropwise to the above-mentioned reaction kettle. At the same time, 0.125 parts of sodium lauryl sulfate, 0.25 parts of fatty alcohol polyoxyethylene ether, and an aqueous ammonium persulfate solution (prepared by dissolving 0.25 parts of ammonium persulfate in 1.5 parts of deionized water) are added dropwise. During the addition, the system temperature is maintained at about 80° C. and the addition speed is controlled. The addition is completed in about 1.5 hours. After the addition is completed, the reaction is kept at 80° C. for 1 hour.

[0057] S5: Cool the reactor to 40° C., add 0.5 parts of oxalic acid dihydrazide, disperse and stir at 40° C. for 30 minutes, cool to room temperature, discharge the material and obtain the highly anti-slip and anti-stick emulsion for water-based pre-printing varnish of Example 4 (abbreviated as: pre-printing emulsion).

[0058] Conventional preprint anti-slip emulsion and the preprint emulsion prepared in Examples 1-4 were used to prepare water-based preprint varnishes according to Table 1, and the varnish properties were tested.

[0059] Table 1 Water-based pre-printing varnish formula

[0060] raw material Raw material model factory Parts by weight Pre-printed emulsion 80 Acrylic resin aqueous solution, solid content 30% HMS-389-9H Hemings 20 Water-based wax emulsion 2541 Longhai Chemical 8 Water-based wax emulsion 255 Longhai Chemical 0.5 Coal-forming aids Ethylene glycol ethyl ether alpha 2 Wetting agent OT75 0.5 defoaming agent TEGO Airex901w German TEGO 0.1 Deionized water 5.4

[0061] The preparation method of water-based pre-printing varnish is as follows: taking the pre-printing emulsion and adding it into the mixing kettle, and then sequentially adding the acrylic resin aqueous solution, water-based wax emulsion, film-forming aid, wetting agent, defoaming agent and deionized water into the mixing kettle. After adding each component, mechanical stirring is carried out for 5 minutes before adding the next raw material. After the addition is completed, stirring is continued for 10 minutes to obtain the water-based pre-printing varnish.

[0062] According to the water-based pre-print varnish formula in Table 1 and the above preparation method, the pre-print emulsions prepared using the high anti-slip and anti-stick emulsions of Examples 1-4 were used to prepare pre-print varnishes A1, A2, A3, and A4 in sequence.

[0063] According to the above water-based pre-print varnish formula and preparation method, the pre-print emulsion uses conventional pre-print anti-slip emulsion Joncryl1685 (Tg-20°C, solid content 43.5%) to prepare comparative example water-based pre-print varnish D1;

[0064] According to the above water-based preprint varnish formula and preparation method, 80 parts of preprint emulsion are used, including 78 parts of conventional preprint anti-slip emulsion Joncryl 1685 (Tg-20°C, solid content 43.5%) and 2 parts of silica powder A200, to prepare comparative water-based preprint varnish D2.

[0065] Effect evaluation:

[0066] Unless otherwise specified, the following sample preparation and testing were carried out at a temperature of 25°C and a humidity of 60%.

[0067] Test sample preparation:

[0068] 140g of pre-coated paper printed with water-based ink but not varnished was coated with the water-based pre-print varnish prepared in Examples 1-4 and Comparative Examples 1-2, respectively, using a 300-line color wheel. After standing for 2 hours, the varnished paper samples were tested for their properties.

[0069] Performance testing:

[0070] Temperature resistance: Tested using a heat sealer at a pressure of 31kPa, with hot pressing for 10 seconds. Lay the varnish side of the varnished paper against the varnished side, and gradually increase the hot pressing temperature. The temperature at which adhesion damage occurs on the coating surface is the temperature resistance value of the varnish.

[0071] Abrasion resistance test: HD-A507 printing ink decolorization abrasion resistance tester, test conditions: frequency 85 times / minute, A4 test paper, friction times 400 times, observe the discoloration of the varnish ink on the paper;

[0072] Anti-slip angle: tested by inclined plane friction coefficient meter, parameters: inclined plane lifting speed: 2° / s, three tests (error between data <3 degrees) and average value.

[0073] Anti-adhesion performance: Take the printed glossy paper, cut it into 10cm*20cm strips, fold it into 10cm*10cm strips with the glossy side facing the glossy side, evenly add 6 drops of deionized water on the glossy surface in the middle, press a 1kg weight on the surface, and place it in a constant temperature and humidity chamber at 65℃ and 95% humidity for 4 hours. Take it out and observe the changes in the coating surface of the printed paper.

[0074] Storage stability: Place the varnish at a temperature of 25°C and a humidity of 60% for three months and observe whether there is stratification or precipitation in the varnish liquid.

[0075] The glazing oils A1, A2, A3, and A4 obtained in Comparative Examples D1 and D2 and Examples 1 to 4 were subjected to the above-mentioned performance tests, and the performance test results of the ink-based paper after glazing are shown in Table 2:

[0076] Table 2

[0077] Serial number Heat resistance wear-resistant Anti-stick Anti-slip corner Solution state of varnish after three months of standing A1 170℃ No fading No adhesion 28° No change A2 160℃ No fading Slight adhesion 32° No change A3 165℃ No fading No adhesion 30° No change A4 168℃ No fading No adhesion 28° No change D1 120℃ Slight discoloration Severe adhesion 20° No change D2 130℃ Slight discoloration Partial adhesion 18° Layered, with a small amount of sediment at the bottom

[0078] Storage stability results, see Figure 1 As can be seen from the figure, compared with the water-based varnishes A1-A4 formulated using the emulsions prepared in Examples 1-4, the water-based varnish in Comparative Example D2, which was formulated using a physical mixture of a conventional preprinted emulsion and silica powder, exhibited significant stratification after storage for a period of time, with a small amount of sediment at the bottom of the bottle. The water-based varnishes A1-A4 formulated using the emulsions prepared in Examples 1-4 exhibited good storage stability.

[0079] The results show that the aqueous emulsions prepared in Examples 1-4 of the present invention have better wear resistance, anti-blocking and anti-slip properties than the conventional pre-printing emulsions in Comparative Examples 1 and 2; compared with the physical mixture of conventional emulsions and silica powder, the aqueous pre-printing varnish prepared with them as the main component has better storage stability and has good applicability in the field of aqueous pre-printing varnish.

Claims

1. A method for preparing a highly anti-slip and anti-stick emulsion for water-based pre-printing varnish, the method comprising the following steps: S1: Disperse silica powder, aqueous acrylic acid dispersion resin solution, defoamer, and deionized water uniformly to obtain S1 powder dispersion; S2: Add all the obtained S1 micropowder dispersion, part of the total amount of the mixed core layer reaction monomers, and part of the emulsifier into the reactor, stir at 30-50°C for 10-40 minutes, then stir and heat. When the temperature in the reactor reaches 75-85°C, add part of the initiator and maintain the reaction at 75-85°C for 0.5-2 hours; S3: Add the remaining mixed core layer reaction monomers, a portion of the emulsifier, and a portion of the initiator to the reactor simultaneously, controlling the system temperature at 75-85°C during the addition process. After the addition is complete, keep the temperature at 75-85°C for 0.5-2 hours; S4: adding the mixed shell reaction monomers, the remaining emulsifier, and the remaining initiator dropwise to the reactor, controlling the system temperature at 75-85° C. during the addition process, and maintaining the reaction at 75-85° C. for 0.5-2 hours after the addition is complete. The mixed shell reaction monomers include butyl acrylate and / or isooctyl acrylate accounting for 15%-20% of the total raw material mass, divinylbenzene accounting for 0.15%-0.2% of the total raw material mass, and diacetone acrylamide accounting for 0.5%-1% of the total raw material mass. S5: Cooling to 30-50°C, adding oxalic acid dihydrazide, stirring for 20-60 minutes, and cooling to room temperature to obtain a high anti-slip and anti-stick emulsion for water-based pre-printing varnish, wherein the amount of oxalic acid dihydrazide accounts for 0.5%-1% of the total raw material mass; In S2, the mixed core layer reaction monomers are compound A and compound B: compound A is styrene and / or methyl methacrylate, and compound B is butyl acrylate and / or isooctyl acrylate, and the total amount of compound A and compound B accounts for 10.5%-16% of the total raw material mass; the mass ratio of compound A to compound B is (15-20):1; The total raw material mass refers to the mass of all substances in S1-S5.

2. The preparation method according to claim 1, characterized in that The emulsifier includes a mixed emulsifier of anionic emulsifier and nonionic emulsifier, the anionic emulsifier is sodium dodecyl sulfonate or sodium dodecyl diphenyl ether disulfonate, the nonionic emulsifier is fatty alcohol polyoxyethylene ether, and the amount of the emulsifier is 1%-2% of the total raw material mass, wherein the mass ratio of the anionic emulsifier to the nonionic emulsifier is 1:(1.6~2).

3. The preparation method according to claim 2, characterized in that The initiator is an aqueous solution of ammonium persulfate, which accounts for 5.25%-11.55% of the total raw material mass.

4. The preparation method according to claim 2, characterized in that The raw materials used in S1 are as follows: 1%-2% silica powder, 40%-60% aqueous acrylate resin solution, and 0.1% defoaming agent in the total raw materials.

5. Use of the highly anti-slip and anti-stick emulsion of water-based pre-printing varnish obtained by the preparation method according to any one of claims 1 to 4 in the preparation of water-based pre-printing varnish.

6. The use according to claim 5, characterized in that The water-based pre-printing varnish comprises, by weight, 78-82 parts of a water-based pre-printing varnish high anti-slip and anti-stick emulsion obtained by the preparation method according to any one of claims 1 to 4, 18-22 parts of an acrylic resin aqueous solution, 7-9 parts of an aqueous wax emulsion, 1-3 parts of a film-forming aid, 0.1-0.8 parts of a wetting agent, 0.05-0.2 parts of a defoaming agent, and 3-8 parts of water.

7. The use according to claim 6, characterized in that The solid content of the acrylic resin aqueous solution is 30±5%, and the film-forming aid is ethylene glycol ethyl ether.

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