Preparation method of special silicon dioxide delustering agent for UV paint

Abstract

The invention relates to the technical field of delustering agents, in particular to a preparation method of a special silicon dioxide delustering agent for UV paint. The preparation method comprises the following steps: S1, dissolving carboxymethyl cellulose and zinc salt into water, then sequentially adding concentrated sulfuric acid and water glass, then adjusting the pH value to 6.0-6.5, and standing to obtain gel; s2, the gel is smashed and aged, then acidification and secondary aging are conducted in sequence, and slurry is obtained; and S3, purifying the slurry, and sequentially performing pulping, spray drying and jet milling to obtain the special silicon dioxide delustering agent for the UV paint. According to the preparation method, the CMC and the zinc salt are simultaneously added in the preparation process, and the matting agent can be more uniformly dispersed on the surface of a paint film under the synergistic effect of the CMC and the zinc salt, so that the flatness, the hand feeling consistency and the matting property of the surface of the paint film are effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of matt agents, in particular to a preparation method of a silica matt agent special for UV paint. BACKGROUND

[0002] The UV paint system is difficult to matt, and generally needs to add a matt powder into the UV paint, such as the matt paint in Chinese patent application No. 201110165698.9, which has the following weight percentage composition: 10-20% of UV resin, 3-8% of a photo initiator, 15-25% of a UV monomer, 5-20% of a matt powder or matt paste, 30-55% of a solvent, 0.3-1% of a dispersing agent and 0.4-1% of a silicone leveling agent. However, in the actual use process, the UV curing time is short, and the matt powder and other various additives in the wet film have not reached a stable state when being instantaneously cured, so that the UV paint film surface has poor uniformity and is uneven, the roughness of different points of the paint film is quite different, and the surface flatness and the hand feeling consistency are poor. SUMMARY

[0003] The application aims to provide a preparation method of a silica matt agent special for UV paint, which can improve the flatness and the hand feeling when the matt agent is used in the UV paint.

[0004] In order to solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of a silica matt agent special for UV paint, comprising the following steps: S1: dissolving carboxymethyl cellulose and a zinc salt into water, then adding concentrated sulfuric acid and water glass in sequence, adjusting the pH to 6.0-6.5, and obtaining a gel after standing; S2: crushing the gel, then aging, acidifying and secondarily aging in sequence, and obtaining a paste; S3: purifying the paste, then spraying, drying and airflow crushing in sequence, and obtaining the silica matt agent special for UV paint.

[0005] The application has the advantages that: in the preparation method, the CMC and the zinc salt are added at the same time, and the synergistic effect of the two can make the matt agent more uniformly dispersed on the paint film surface, effectively improving the flatness, the hand feeling consistency and the matt property of the paint film surface. DETAILED DESCRIPTION

[0006] In order to describe the technical content, the purposes and the effects of the application in detail, the following describes the application in combination with the embodiments.

[0007] A preparation method of a silica matt agent special for UV paint, comprising the following steps: S1: carboxymethyl cellulose (CMC) and zinc salt are dissolved into water, then concentrated sulfuric acid and water glass are added in sequence, the pH is adjusted to 6.0-6.5, and a gel is obtained after standing; S2: the gel is broken and aged, then acidification and secondary aging are carried out in sequence, and a slurry is obtained; S3: the slurry is purified, then beating, spray drying and air flow crushing are carried out in sequence, and a UV paint special silica matting agent is obtained.

[0008] From the above description, the beneficial effects of the present application are that: the preparation method of the present application, CMC and zinc salt are added at the same time in the preparation process, zinc salt will dissolve under neutral or acidic conditions, existing in the form of zinc ions. It can be used as an inorganic dispersant; CMC produces significant thickening effect after dissolving in water, forming a three-dimensional network of interwoven polymer chains, which can be used as a preferential nucleation soft film plate for subsequent reactions, forming a double three-dimensional network composite gel with silica gel, increasing the stability and consistency of the silica gel. The synergistic effect of CMC and zinc salt makes the matting agent more uniformly dispersed on the paint film surface, effectively improving the flatness, hand consistency and matting property of the paint film surface.

[0009] Further, in the process of dissolving carboxymethyl cellulose and zinc salt into water, then adding acid and water glass in sequence, the reaction temperature is maintained at 40-60℃.

[0010] From the above description, the temperature is lower, which is beneficial to the slow reaction of silica particles, and the produced particles are more uniform. If the temperature is too high, the reaction will be violent, and the silica particles will be severely agglomerated.

[0011] Under weak alkaline conditions, zinc salt will first dissolve and then form zinc hydroxide precipitate; if the alkalinity is further increased, it will dissolve again to form soluble zincate. Therefore, the present application limits the pH of the whole reaction process to be acidic to prevent the generation of zinc precipitate.

[0012] Further, the addition amount of carboxymethyl cellulose is 0.5-1.5wt% of the mass of water.

[0013] Further, the addition amount of zinc salt is 0.5-1.5wt% of the mass of water.

[0014] Further, the zinc salt is a soluble zinc salt, which can be one of zinc chloride, zinc chloride, zinc nitrate and zinc acetate.

[0015] Further, when carboxymethyl cellulose and zinc salt are dissolved into water, the stirring rate is 100-300r / min.

[0016] Further, the volume ratio of concentrated sulfuric acid to water in S1 is 0.8-1:26.

[0017] Further, the volume ratio of concentrated sulfuric acid to water glass in S1 is 0.8-1:8.

[0018] As can be seen from the above description, the acid-base neutralization reaction of water glass and sulfuric acid produces silica precipitate.

[0019] Further, the addition rate of water glass is 7.6-8.6 L / h.

[0020] Further, the modulus of water glass is 3.3-3.5, and the SiO2 content is 10-20%.

[0021] As can be seen from the above description, the modulus of water glass affects the physicochemical properties of silica, thereby affecting the application. The present application selects high modulus water glass, which has the advantage of lower cost.

[0022] If the silica concentration in water glass is too high, it will not only precipitate easily, but also cause the reaction to be too violent, and the primary particles generated by the reaction will easily agglomerate; if the concentration is too low, it will affect the production efficiency and cost. Therefore, the SiO2 content is controlled to be 10-20%.

[0023] Further, sodium carbonate is used in S1 to adjust the pH to 6.0-6.5.

[0024] As can be seen from the above description, the formation of silica gel is strongly related to pH, and it is easier to gel when the pH value is close to neutral. The present application uses weakly basic sodium carbonate instead of directly using water glass with stronger basicity to adjust the pH, which can reduce the reaction rate and make the gel more uniform and stable. In addition, water glass is one of the raw materials for synthesizing silica, and if it is used to adjust the pH at the same time, it will also cause the generation of new silica particles, which will also weaken the uniformity of the gel.

[0025] Further, the standing time of S1 is 10-60 min.

[0026] Further, the temperature is raised to 60-95℃ during aging.

[0027] As can be seen from the above description, the reaction temperature before aging is low, and after the gel is allowed to stand, the reaction is still not complete. Therefore, aging is needed to make the unreacted reactants in the gel completely react, making the system stable and providing conditions for the next step of reaction. In addition, high temperature aging can also make unstable silica particles in the system redissolve and then deposit into a stable state, further improving the stability of the system.

[0028] Further, the acidification in S2 is to pH 4.0-4.5.

[0029] From the above description, if the aging pH value is alkaline, it indicates that the water glass is not completely reacted, which will reduce the yield. If the pH value of acidification is too low, not only the equipment will be lost, but also the water washing time will be prolonged, which will affect the energy consumption and production capacity.

[0030] Further, the specific steps of S2 are: after the gel is broken, the temperature is raised to 60-95 DEG C, and aged for 0.5-3h, then acidified to pH 4.0-4.5, aged for 5-60min, to obtain the slurry.

[0031] The concentration of concentrated sulfuric acid in the following examples is 98wt%.

[0032] Embodiment 1 of the present application is a preparation method of a special silica matting agent for UV paint, the steps are as follows: S1: 26L of water is added to the reaction kettle, heated to 58 DEG C, then 0.5wt% of carboxymethyl cellulose and 0.5wt% of zinc chloride are added, and stirred uniformly, the stirring rate is 300r / min; S2: 0.8L of concentrated sulfuric acid is added to the reaction kettle, and the reaction temperature is kept at 60 DEG C; S3: 8L of water glass is added to the reaction kettle at a rate of 8.4L / h, and the reaction temperature is 60 DEG C; the modulus of the water glass is 3.42, and the SiO2 content is 12%; S4: 20wt% of sodium carbonate is added to the reaction kettle to adjust the pH to 6.5, and the gel is obtained after standing for 30min; S5: start stirring, break the gel, and raise the temperature to 85 DEG C, and age for 1h, S6: add concentrated sulfuric acid to the reaction kettle to acidify to pH 4.2, and age for 10min to obtain the slurry; S7: after the slurry is purified, it is sequentially subjected to pressure filtration, washing, beating-up, spray drying and air flow crushing to obtain the special silica matting agent for UV paint.

[0033] Embodiment 2 of the present application is: The difference between embodiment 2 and embodiment 1 is only that 1.0wt% of carboxymethyl cellulose and 0.5wt% of zinc chloride are added in S1.

[0034] Embodiment 3 of the present application is: The difference between embodiment 3 and embodiment 1 is only that 1.5wt% of carboxymethyl cellulose and 0.5wt% of zinc chloride are added in S1.

[0035] Embodiment 4 of the present application is: The difference between embodiment 4 and embodiment 1 is only that 1.0wt% of carboxymethyl cellulose and 1.0wt% of zinc chloride are added in S1.

[0036] Embodiment 5 of the present application is: Example 5 differs from Example 1 only in that S1 adds 1.0 wt% carboxymethyl cellulose and 1.5 wt% zinc chloride.

[0037] Example 6 of the present application is a preparation method of a special silica matting agent for UV paint, the steps are as follows: S1: 26L water is added to the reaction kettle, heated to 40℃, then 1wt% carboxymethyl cellulose and 1wt% zinc chloride are added, stirred uniformly, the stirring rate is 100r / min; S2: 1L of concentrated sulfuric acid is added to the reaction kettle, and the reaction temperature is kept at 50℃; S3: 8L of water glass is added to the reaction kettle at a rate of 7.6L / h, the reaction temperature is 50℃; the modulus of the water glass is 3.3, and the SiO2 content is 10%; S4: 20wt% of sodium carbonate is added to the reaction kettle to adjust the pH to 6.2, and the gel is obtained after standing for 10min; S5: start stirring, break the gel, and heat to 60℃, aging for 3h, S6: add concentrated sulfuric acid to the reaction kettle to acidify to pH 4.0, and age for 5min to obtain the slurry; S7: after the slurry is purified, it is sequentially subjected to pressure filtration, washing, beating, spray drying and air flow crushing to obtain the special silica matting agent for UV paint.

[0038] Example 7 of the present application is a preparation method of a special silica matting agent for UV paint, the steps are as follows: S1: 26L water is added to the reaction kettle, heated to 60℃, then 1.5wt% carboxymethyl cellulose and 1.5wt% zinc chloride are added, stirred uniformly, the stirring rate is 200r / min; S2: 0.9L of concentrated sulfuric acid is added to the reaction kettle, and the reaction temperature is kept at 60℃; S3: 8L of water glass is added to the reaction kettle at a rate of 8.6L / h, the reaction temperature is 60℃; the modulus of the water glass is 3.5, and the SiO2 content is 20%; S4: 20wt% of sodium carbonate is added to the reaction kettle to adjust the pH to 6.5, and the gel is obtained after standing for 60min; S5: start stirring, break the gel, and heat to 5℃, aging for 0.5h, S6: add concentrated sulfuric acid to the reaction kettle to acidify to pH 4.5, and age for 60min to obtain the slurry; S7: after the slurry is purified, it is sequentially subjected to pressure filtration, washing, beating, spray drying and air flow crushing to obtain the special silica matting agent for UV paint.

[0039] Comparative Example 1 of the present application is: The difference between Comparative Example 1 and Example 1 is only that 1.0wt% carboxymethyl cellulose is added in S1, and no zinc chloride is added.

[0040] Comparative Example 2 of the present application is: The difference between Comparative Example 2 and Example 1 is only that 1.0wt% zinc chloride is added in S1, and no carboxymethyl cellulose is added.

[0041] Comparative Example 3 of the present application is: The difference between Comparative Example 3 and Example 1 is only that no zinc chloride and carboxymethyl cellulose is added in S1.

[0042] Application performance test: The silica matting powder prepared in Examples 1-7 and Comparative Examples 1-3 is crushed to D50=5.0μm, and then added to a UV epoxy acrylate resin paint, and a paint film is prepared by roll coating and curing.

[0043] 1) UV paint formula: consisting of epoxy acrylate resin (UV-2215) 100 parts, acrylate monomer (EAD-100) 80 parts, photoinitiator (Irgacure 784) 2 parts and silica matting agent 9 parts by weight. 2) Paint film preparation method: the substances in the formula are added to the paint mixing tank in order, dispersed at a speed of 800r / min for 20min, then stand for 10min, finally coated with UV roll coater, and photocured to obtain the required paint film.

[0044] 3) Test method: Gloss (60° angle gloss meter) according to GB 1743-1979; Maximum roughness difference ΔRz: first test the Rz value of 10 points of the paint film with a surface roughness meter, then subtract the minimum value from the maximum value to obtain ΔRz.

[0045] Table 1

[0046] Examples 1-3, the zinc chloride content is constant, the CMC content is increased, the pore volume and the matting performance first increase and then decrease, and the ΔRz decreases to 0.18 and remains unchanged, considering the matting efficiency and cost, the comprehensive performance is optimal when the CMC content is 1%; Examples 2 and 4-5, keeping the CMC content at 1%, the zinc oxide content is increased, the pore volume and the matting performance first increase and then decrease, and the ΔRz first decreases and then increases, in general, the performance of Example 4 is optimal, with the largest pore volume, the lowest gloss and ΔRz, and the best hand consistency.

[0047] Comparative Example 1 only adds CMC, Comparative Example 3, pore volume, gloss and delta Rz are basically the same, which shows that pure CMC cannot improve the extinction and the consistency of hand feeling; Comparative Example 2 only adds zinc chloride, Comparative Example 3, pore volume, gloss and delta Rz are also basically the same, which shows that pure zinc chloride cannot improve the extinction and the consistency of hand feeling; Comparative Example 4, Comparative Example 3 does not add CMC and zinc salt, the pore volume is obviously reduced, the gloss and delta Rz are increased, that is, the extinction performance and the consistency of hand feeling are poor.

[0048] In summary, the preparation method of the UV paint special silica extinction agent provided by the application has the following advantages: 1. CMC and zinc salt are added at the same time in the preparation process, and the synergistic effect of CMC and zinc salt effectively improves the flatness, hand feeling consistency and extinction of the paint film surface.

[0049] 2. A lower reaction temperature is used, and the produced silica particles are more uniform. If the temperature is too high, the reaction will be violent, and the silica particles will be seriously agglomerated.

[0050] 3. The pH of the reaction process is limited to be acidic to prevent the generation of zinc precipitates.

[0051] 4. Weakly basic sodium carbonate is used to replace the more strongly basic water glass to adjust the pH, which can reduce the reaction rate and make the gel more uniform and stable.

[0052] The above is only an embodiment of the application, and does not limit the patent range of the application, and any equivalent transformation made by using the specification of the application, or direct or indirect application in related technical fields, is also included in the patent protection range of the application.

Claims

1. A method for preparing a special silica matting agent for UV paint, characterized in that, The method comprises the following steps: S1: dissolving carboxymethyl cellulose and zinc salt into water, then adding concentrated sulfuric acid and water glass in sequence, adjusting pH to 6.0-6.5, and standing to obtain a gel; S2: crushing the gel, aging, acidifying, and secondarily aging to obtain a slurry; S3: purifying the slurry, then performing beating-up, spray drying, and airflow crushing to obtain a UV paint special-purpose silica matting agent.

2. The process for the preparation of a UV paint specific silica matting agent according to claim 1, characterized in that, In the process of dissolving carboxymethyl cellulose and zinc salt into water, then adding acid and water glass in sequence, the reaction temperature is kept at 40-60℃.

3. The preparation method of the UV paint-specific silica matting agent according to claim 1, characterized in that, The addition amount of carboxymethyl cellulose is 0.5-1.5wt% of the mass of water.

4. The preparation method of the UV paint-specific silica matting agent according to claim 1, characterized in that, The addition amount of zinc salt is 0.5-1.5wt% of the mass of water.

5. The preparation method of the UV paint-specific silica matting agent according to claim 1, characterized in that, When dissolving carboxymethyl cellulose and zinc salt into water, the stirring rate is 100-300r / min.

6. The method of claim 1, wherein the UV paint special-purpose silica matting agent is prepared by the steps of: In S1, the volume ratio of concentrated sulfuric acid to water is 0.8-1:

26.

7. The preparation method of the UV paint-specific silica matting agent according to claim 1, characterized in that, The addition rate of water glass is 7.6-8.6L / h.

8. The method of claim 1, wherein the UV paint special-purpose silica matting agent is prepared by the steps of: The modulus of water glass is 3.3-3.5, and the SiO2 content is 10-20%.

9. The preparation method of the UV paint-specific silica matting agent according to claim 1, characterized in that, When aging, the temperature is raised to 60-95℃.

10. The method of claim 1, wherein the UV paint special-purpose silica matting agent is prepared by the steps of: In S2, the pH is acidified to 4.0-4.5.

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