An acrylic hardening coating, its preparation method and an acrylic product

Abstract

The present invention discloses an acrylic hardening coating, a preparation method thereof and an acrylic product. The acrylic hardening coating comprises the following components in parts by mass: 20-30 parts of aliphatic polyurethane acrylate, 1-3 parts of photoinitiator, 50-70 parts of organic solvent, 0.1-0.3 parts of leveling agent, and 1-3 parts of modified titanium dioxide. The present invention uses aliphatic polyurethane acrylate containing benzene ring and urea group as the base material and modified titanium dioxide as the enhancer. The photoinitiator can form an acrylic hardening coating under photocuring. The introduction of benzene ring and urea group increases the rigidity of the polyurethane acrylate molecular chain, thereby improving the strength of the coating. In addition, methyl 5-allyl-3-methoxysalicylate adsorbed by modified titanium dioxide can react with aliphatic polyurethane acrylate through carbon-carbon double bonds during photocuring, which can significantly improve the hardness of the coating while improving the dispersibility of titanium dioxide in the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of organic coatings, and particularly relates to an acrylic hardening coating, a preparation method thereof, and an acrylic product. Background Art

[0002] Acrylic, namely plexiglass, is polymerized from methyl methacrylate monomer (MMA), and has high light transmittance, excellent weather resistance, relatively high surface hardness and surface gloss, good high-temperature resistance, and good processing plasticity, and is known as the "plastic queen".

[0003] Hardness is one of the parameters that can best reflect the production process and technology of cast acrylic sheets, and directly affects whether the sheets will shrink, bend and deform, and whether cracks will appear on the surface during processing. Coating a hardening coating on the surface of an acrylic sheet is an effective method to improve the hardness of the acrylic sheet. For example, CN119144035A discloses a 6H scratch-resistant acrylic sheet, a preparation method thereof and an application. A hardening coating is prepared on the acrylic sheet. The hardening coating includes, by mass percentage: 20-60% of polyurethane acrylate resin, 5-30% of reactive monomer, 0.5-2% of metal oxide nanoparticles, <10% of photoinitiator, and the balance is auxiliary agent. This method can quickly form a hardening coating under photocuring conditions, improving the wear resistance and toughness of the acrylic sheet. However, the light transmittance of the acrylic sheet containing the hardening coating is not evaluated. CN103540256A discloses an ultraviolet-curable high-hardness anti-fingerprint coating for acrylic and its composite substrates. The coating includes the following components in parts by weight: 5-10 parts of fluorine-modified acrylate oligomer, 10-20 parts of silicon-modified acrylate oligomer, 50-65 parts of high-functional acrylate oligomer, 5-7 parts of photoinitiator, and 0.05-3 parts of auxiliary agent. This coating can reach a high hardness of 8H when coated on an acrylic substrate, and at the same time has the advantages of high light transmittance and anti-fingerprint. However, the components of this coating contain a variety of organic reagents, and the price of fluorocarbon resin is relatively high, which limits its application.

[0004] Currently, there is little research on acrylic hardening coatings, and there are few selections for coating components. It is necessary to provide high-performance acrylic hardening coatings. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides an acrylic hardening coating, which includes the following components in parts by mass:

[0006] 20-30 parts of aliphatic polyurethane acrylate, 1-3 parts of photoinitiator, 50-70 parts of organic solvent, 0.1-0.3 parts of leveling agent, and 1-3 parts of modified titanium dioxide.

[0007] In the present invention, at low temperature, the amino group of diethylene glycol amine preferentially reacts with terephthalic diisocyanate, so that the hydroxyl groups of diethylene glycol amine are located at both ends of the structure and the benzene rings of terephthalic diisocyanate are located in the middle of the structure, obtaining a chain extender. After L-lysine triisocyanate polymerizes with polyethylene glycol under the action of a catalyst, a chain extender is added for further reaction to obtain an intermediate, and finally it reacts with hydroxyethyl acrylate to obtain an aliphatic polyurethane acrylate. The molecular chain of the aliphatic polyurethane acrylate has a urea group formed by the reaction of a benzene ring, isocyanate and amino group. The introduction of the benzene ring and the urea group increases the rigidity of the molecular chain of the polyurethane acrylate, thereby enhancing the strength of the coating.

[0008] Furthermore, the preparation method of the aliphatic polyurethane acrylate includes, by mass parts,

[0009] Mix 10 - 20 parts of terephthalic diisocyanate with 40 - 60 parts of N,N-dimethylformamide, then add 10 - 15 parts of diethylene glycol amine and stir and react at 0 - 5 °C to obtain a chain extender;

[0010] Mix 15 - 20 parts of L-lysine triisocyanate, 0.01 - 0.03 parts of a catalyst, 20 - 50 parts of ethyl acetate, and 15 - 20 parts of polyethylene glycol, then add 5 - 10 parts of the chain extender and stir and react, and finally add 4 - 8 parts of hydroxyethyl acrylate and continue to stir and react to obtain an aliphatic polyurethane acrylate.

[0011] Furthermore, the catalyst includes at least one of dibutyltin dilaurate, dimethyltin diolate, and stannous octoate;

[0012] The molecular weight of the polyethylene glycol is 400 - 6000.

[0013] Titanium dioxide has stable chemical properties. Adding an appropriate amount of titanium dioxide filler can significantly improve the strength and hardness of polymer matrix composites. However, as an inorganic material, titanium dioxide has poor compatibility with aliphatic polyurethane acrylate. Based on the fact that it can effectively improve the hardness of the coating only when added to a certain proportion, it is necessary to modify titanium dioxide to improve compatibility. In the present invention, methyl 5-allyl-3-methoxysalicylate is adsorbed on titanium dioxide to obtain modified titanium dioxide. When the coating is cured under light, the carbon-carbon double bond of the modified titanium dioxide can react with the aliphatic polyurethane acrylate, which can significantly improve the hardness of the coating while enhancing the dispersibility of titanium dioxide in the coating.

[0014] Furthermore, the preparation method of the modified titanium dioxide includes, by mass parts,

[0015] Mix 5 - 10 parts of titanate, 0.5 - 1 part of hexamethylenetetramine with 80 - 120 parts of a first solvent, then carry out a solvothermal reaction, collect the insoluble matter and calcine it to obtain titanium dioxide;

[0016] Mix 5 - 10 parts of titanium dioxide, 1 - 3 parts of methyl 5 - allyl - 3 - methoxysalicylate and 50 - 60 parts of a second solvent by stirring to obtain modified titanium dioxide.

[0017] For titanium dioxide, its specific surface area and particle size distribution have a significant impact on its performance. In the present invention, β - cyanoalanine is also added during the solvothermal reaction to regulate the structure of titanium dioxide.

[0018] Further, after mixing the titanate, hexamethylenetetramine and the first solvent, add β - cyanoalanine in an amount of 0.05 - 0.1 times the mass of the titanate;

[0019] The solvothermal reaction is maintained at 160 - 180 °C for 5 - 8 h;

[0020] The first solvent includes at least one of water, ethanol, and acetone;

[0021] The second solvent includes at least one of ethanol, acetone, chloroform, and ether.

[0022] It should be noted that in the present invention, the type of titanate does not need to be strictly limited. Exemplarily, it can be at least one of tetrabutyl titanate and tetraisopropyl titanate.

[0023] Further, the photoinitiator is at least one of methyl phenylglyoxylate and 1 - hydroxycyclohexyl phenyl ketone.

[0024] Further, the solvent includes at least one of propylene glycol monomethyl ether and ethyl acetate.

[0025] The present invention also provides a method for preparing the above - mentioned acrylic hardening coating, including,

[0026] Add aliphatic polyurethane acrylate and modified titanium dioxide to a solvent and stir - mix to obtain component A,

[0027] Stir - mix the photoinitiator and the leveling agent to obtain component B;

[0028] Mix component A and component B evenly to obtain the acrylic hardening coating.

[0029] The present invention also provides an acrylic product, including an acrylic material and a coating formed by coating the above - mentioned acrylic hardening coating on the surface of the acrylic material.

[0030] The present invention also provides a method for preparing an acrylic product, including,

[0031] Coat the above - mentioned acrylic hardening coating on the surface of the acrylic material, and then cure it under light to form a hardening coating on the surface of the acrylic material to obtain the acrylic product.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention uses an aliphatic polyurethane acrylate containing a benzene ring and a urea group as the base material, and modified titanium dioxide as the reinforcing agent. Combined with a photoinitiator, an acrylic hardening coating can be formed under photocuring. The introduction of the benzene ring and the urea group increases the rigidity of the polyurethane acrylate molecular chain, thereby improving the strength of the coating. In addition, methyl 5-allyl-3-methoxysalicylate adsorbed by the modified titanium dioxide can react with the aliphatic polyurethane acrylate through a carbon-carbon double bond during photocuring, which can significantly improve the hardness of the coating while enhancing the dispersibility of titanium dioxide in the coating. Detailed implementation manners

[0034] Some raw materials used in the examples and comparative examples of the present invention are introduced as follows:

[0035] Polyethylene glycol, with a molecular weight of 600, model PEG600, purchased from Shandong Longhui Chemical Co., Ltd.;

[0036] Leveling agent, model BYK333, purchased from BYK-Chemie GmbH.

[0037] Other raw materials not mentioned are common raw materials. The above content is only for helping to explain the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase from the market or prepare the same / similar raw materials by themselves. These contents will not be elaborated in the examples anymore.

[0038] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] Example 1

[0041] A preparation method of an acrylic hardening coating is as follows:

[0042] S1. Weigh 2.5 kg of aliphatic polyurethane acrylate, 0.1 kg of methyl phenylglyoxylate, 0.1 kg of 1-hydroxycyclohexyl phenyl ketone, 6 kg of propylene glycol methyl ether, 1 kg of ethyl acetate, 0.015 kg of leveling agent, and 0.2 kg of modified titanium dioxide.

[0043] S2. Mix aliphatic polyurethane acrylate, modified titanium dioxide, propylene glycol methyl ether, and ethyl acetate, and then stir at a speed of 350 rpm for 15 minutes to obtain Component A.

[0044] S3. Mix methyl phenylglyoxylate, 1-hydroxycyclohexyl phenyl ketone, and leveling agent, and then stir at a speed of 300 rpm for 10 minutes to obtain Component B.

[0045] S4. Mix Component A and Component B, and then stir at a speed of 500 rpm for 10 minutes to obtain an acrylic hardening coating.

[0046] Among them, the preparation method of aliphatic polyurethane acrylate is as follows.

[0047] T1. Mix 1.5 kg of p-phenylene diisocyanate with 5 kg of N,N-dimethylformamide, then add 1.25 kg of diethylene glycol amine, stir at 2 °C at a speed of 350 rpm for 2 hours, transfer the product to ethyl acetate to collect the precipitated solid, wash it three times with ethyl acetate, and dry it under vacuum to obtain a chain extender.

[0048] T2. Mix 1.8 kg of L-lysine triisocyanate, 0.002 kg of dibutyltin dilaurate, 3.5 kg of ethyl acetate, and 1.6 kg of polyethylene glycol 600, stir and mix at a speed of 350 rpm for 1 hour, then add 0.8 kg of chain extender and continue to stir and react for 3 hours. Finally, add 0.5 kg of hydroxyethyl acrylate and continue to stir and react for 2 hours, and then rotary evaporate the excess solvent ethyl acetate to obtain aliphatic polyurethane acrylate.

[0049] The preparation method of modified titanium dioxide is as follows.

[0050] V1. Mix 0.8 kg of tetrabutyl titanate, 0.08 kg of hexamethylenetetramine, and 10 kg of 75% ethanol aqueous solution, stir at a speed of 350 rpm for 15 minutes, then transfer to a solvent thermal reaction at 175 °C for 6 hours. After completion, naturally cool, collect the insoluble matter, wash it three times with water and ethanol respectively, dry it at 120 °C, and then transfer it to a muffle furnace at 500 °C in an air atmosphere and calcine it for 2 hours to obtain titanium dioxide.

[0051] V2. Mix 0.75 kg of titanium dioxide, 0.2 kg of 5-allyl-3-methoxysalicylate methyl ester, and 5 kg of chloroform, stir at a speed of 350 rpm for 2 hours, then filter and dry it at 120 °C to obtain modified titanium dioxide.

[0052] Example 2

[0053] Compared with Example 1, the difference lies in that the preparation method of the modified titanium dioxide is as follows

[0054] V1. Mix 0.8 kg of tetrabutyl titanate, 0.08 kg of hexamethylenetetramine, 0.04 kg of β-cyanoalanine, and 10 kg of an ethanol aqueous solution with a mass fraction of 75%, stir at a rotation speed of 350 rpm for 15 min, then transfer to a solvent thermal reaction at 175 °C for 6 h. After completion, naturally cool, collect the insoluble matter, wash it three times with water and ethanol respectively, dry it at 120 °C, and then transfer it to a muffle furnace in an air atmosphere at 500 °C for calcination for 2 h to obtain titanium dioxide;

[0055] V2. Mix 0.75 kg of titanium dioxide, 0.2 kg of methyl 5-allyl-3-methoxysalicylate, and 5 kg of chloroform, stir at a rotation speed of 350 rpm for 2 h, filter, and dry at 120 °C to obtain the modified titanium dioxide.

[0056] Examples 3 and 4

[0057] Compared with Example 2, the difference lies in that the mass of β-cyanoalanine in step V1 of the preparation method of the modified titanium dioxide is 0.06 kg and 0.08 kg respectively.

[0058] Comparative Example 1

[0059] Compared with Example 1, the difference lies in that the preparation method of the aliphatic polyurethane acrylate is as follows

[0060] Mix 1.8 kg of L-lysine triisocyanate, 0.002 kg of dibutyltin dilaurate, 3.5 kg of ethyl acetate, and 2.4 kg of polyethylene glycol 600, stir and mix at a rotation speed of 350 rpm for 4 h, finally add 0.5 kg of hydroxyethyl acrylate, continue to stir and react for 2 h, and then rotary evaporate the excess solvent ethyl acetate to obtain the aliphatic polyurethane acrylate.

[0061] Comparative Example 2

[0062] Compared with Example 3, the difference lies in that the preparation method of the aliphatic polyurethane acrylate is as follows

[0063] Mix 1.8 kg of L-lysine triisocyanate, 0.002 kg of dibutyltin dilaurate, 3.5 kg of ethyl acetate, and 2.4 kg of polyethylene glycol 600, stir and mix at a rotation speed of 350 rpm for 4 h, finally add 0.5 kg of hydroxyethyl acrylate, continue to stir and react for 2 h, and then rotary evaporate the excess solvent ethyl acetate to obtain the aliphatic polyurethane acrylate.

[0064] Comparative Example 3

[0065] Compared with Example 3, the difference is that titanium dioxide is used to replace the modified titanium dioxide. The preparation method of titanium dioxide is as follows:

[0066] 0.8 kg of tetrabutyl titanate, 0.08 kg of hexamethylenetetramine, and 10 kg of an ethanol aqueous solution with a mass fraction of 75% were mixed and stirred at a speed of 350 rpm for 15 min, then transferred to a solvothermal reaction at 175 °C for 6 h. After completion, it was naturally cooled, and the insoluble matter was collected and washed three times with water and ethanol respectively. After being dried at 120 °C, it was transferred to a muffle furnace at 500 °C in an air atmosphere and calcined for 2 h to obtain titanium dioxide.

[0067] Comparative Example 4

[0068] Compared with Example 3, the difference is that titanium dioxide is used to replace the modified titanium dioxide. The preparation method of titanium dioxide is as follows:

[0069] 0.8 kg of tetrabutyl titanate, 0.08 kg of hexamethylenetetramine, 0.04 kg of β-cyanoalanine, and 10 kg of an ethanol aqueous solution with a mass fraction of 75% were mixed and stirred at a speed of 350 rpm for 15 min, then transferred to a solvothermal reaction at 175 °C for 6 h. After completion, it was naturally cooled, and the insoluble matter was collected and washed three times with water and ethanol respectively. After being dried at 120 °C, it was transferred to a muffle furnace at 500 °C in an air atmosphere and calcined for 2 h to obtain titanium dioxide.

[0070] Application Examples 1-8

[0071] The preparation method of acrylic products is as follows:

[0072] The acrylic hardening coatings prepared in Examples 1-4 and Comparative Examples 1-4 were uniformly coated onto the acrylic board surface through a coating roller. The linear speed of the acrylic board was 3 m / min, and the linear speed of the coating roller was 6 m / min. After coating, it was sent into an oven at 85 °C for leveling, and then irradiated with a mercury lamp of 350 mJ / cm 2 to prepare a hardening coating with a thickness of 50 μm on the acrylic board surface.

[0073] Test Example

[0074] The specific surface area and average particle size of the titanium dioxide prepared in the examples and comparative examples were tested using a nitrogen adsorption-desorption instrument and a laser particle size analyzer, and the results are shown in Table 1.

[0075] Table 1 Results of the specific surface area and average particle size of titanium dioxide

[0076] <![CDATA[Specific surface area (m 2 / g)]]> Average particle size (nm) Example 1 35.6 128 Example 2 48.2 89 Example 3 55.7 83 Example 4 46.1 92

[0077] It can be seen that compared with Example 1, the specific surface area of the titanium dioxide prepared in Examples 2-4 increases and the average particle size decreases. This is because the introduction of β-cyanoalanine effectively regulates the structure of titanium species in the initial stage of the solvothermal reaction, making it have more abundant pores while having a smaller particle size, a larger specific surface area and a lower particle size. Such titanium dioxide has more binding sites and can better interact with aliphatic polyurethane acrylate.

[0078] Referring to the standards GB / T 6739-2022 "Paints and varnishes - Determination of film hardness by pencil test", GB / T 9286-2021 "Paints and varnishes - Cross-cut test" and GB / T 20624.1-2006 "Paints and varnishes - Rapid deformation (impact resistance) test - Part 1: Falling weight test (large area punch)", the hardness, adhesion and impact resistance of the hardening coatings of the acrylic products in the application examples were tested respectively, and the results are shown in Table 2.

[0079] Table 2 Test results of hardness, adhesion and impact resistance of the hardening coating

[0080]

[0081]

[0082] It can be seen from the test results in Table 2 that the hardness, adhesion and impact resistance of Application Examples 1-4 of the present invention are significantly better than those of Application Examples 5-8. Comparing Application Example 1 and Application Example 5 and Application Example 2 and Application Example 6, because the introduction of benzene rings and urea groups increases the rigidity of the polyurethane acrylate molecular chain, thereby improving the strength of the coating; comparing Application Example 3 and Application Example 7 and Application Example 8, it shows that directly adding titanium dioxide cannot significantly improve the hardness of the coating, which is due to the poor dispersibility of titanium dioxide. The methyl 5-allyl-3-methoxysalicylate adsorbed by the modified titanium dioxide can react with aliphatic polyurethane acrylate through carbon-carbon double bonds during photocuring, which can significantly improve the hardness of the coating while improving the dispersibility of titanium dioxide in the coating. Due to the large specific surface area and small particle size of titanium dioxide, the titanium dioxide modified with methyl 5-allyl-3-methoxysalicylate can be well dispersed in the aliphatic polyurethane acrylate structure under photocuring. The presence of benzene rings and urea groups increases the rigidity of the polyurethane acrylate molecular chain, and Application Example 3 has the highest hardness, adhesion and impact resistance.

[0083] Referring to the standard GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics", the transmittance of the acrylic products in the application examples was measured, and the results are shown in Table 3.

[0084] Table 3 Transmittance results of the acrylic products in the application examples

[0085] Light transmittance (%) Application Example 1 92.2 Application Example 2 92.8 Application Example 3 93.3 Application Example 4 92.6 Application Example 5 91.2 Application Example 6 91.5 Application Example 7 90.3 Application Example 8 90.5 Acrylic sheet 93.5

[0086] As can be seen from the results in Table 3, the light transmittance of the acrylic product with a hardening coating constructed in the embodiment of the present invention is very close to that of the acrylic sheet substrate.

[0087] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An acrylic hardening coating, characterized in that, It comprises the following components by mass parts: 20 - 30 parts of aliphatic polyurethane acrylate, 1 - 3 parts of photoinitiator, 50 - 70 parts of organic solvent, 0.1 - 0.3 parts of leveling agent, 1 - 3 parts of modified titanium dioxide; The preparation method of the aliphatic polyurethane acrylate comprises, by mass parts, Mix 10 - 20 parts of p-phenylene diisocyanate with 40 - 60 parts of N,N-dimethylformamide, then add 10 - 15 parts of diethanolamine and stir and react at 0 - 5 °C to obtain a chain extender; Stir and mix 15 - 20 parts of L-lysine triisocyanate, 0.01 - 0.03 parts of catalyst, 20 - 50 parts of ethyl acetate, 15 - 20 parts of polyethylene glycol, then add 5 - 10 parts of chain extender and stir and react, and finally add 4 - 8 parts of hydroxyethyl acrylate and continue to stir and react to obtain aliphatic polyurethane acrylate; The preparation method of the modified titanium dioxide comprises, by mass parts, Mix 5 - 10 parts of titanate, 0.5 - 1 part of hexamethylenetetramine with 80 - 120 parts of the first solvent, then carry out a solvothermal reaction, collect the insoluble matter and calcine to obtain titanium dioxide; Stir and mix 5 - 10 parts of titanium dioxide, 1 - 3 parts of 5-allyl-3-methoxysalicylate methyl ester and 50 - 60 parts of the second solvent to obtain modified titanium dioxide.

2. The acrylic hardening coating according to claim 1, wherein The catalyst includes at least one of dibutyltin dilaurate, dimethyltin diolate, stannous octoate; The molecular weight of the polyethylene glycol is 400 - 6000.

3. The acrylic hardening coating according to claim 1, characterized in that, After mixing the titanate, hexamethylenetetramine and the first solvent, add 0.05 - 0.1 times the mass of the titanate of β-cyanoalanine; The solvothermal reaction is carried out at 160 - 180 °C for 5 - 8 h; The first solvent includes at least one of water, ethanol, acetone; The second solvent includes at least one of ethanol, acetone, chloroform and ether.

4. The acrylic hardening coating according to claim 1, wherein The photoinitiator is at least one of methyl phenyloxoacetate, 1-hydroxycyclohexyl phenyl ketone.

5. The acrylic hardening coating according to claim 1, characterized in that, The organic solvent includes at least one of propylene glycol monomethyl ether, ethyl acetate.

6. A preparation method of the acrylic hardening coating according to any one of claims 1 to 5, characterized in that, It comprises Add the aliphatic polyurethane acrylate and the modified titanium dioxide into the organic solvent and stir and mix to obtain component A, Stir and mix the photoinitiator and the leveling agent to obtain component B; Mix component A and component B evenly to obtain the acrylic hardening coating.

7. An acrylic product, characterized in that, It comprises an acrylic material and a coating formed by the acrylic hardening coating according to any one of claims 1 - 5 coated on the surface of the acrylic material.

8. A preparation method of an acrylic product, characterized in that, It comprises Coat the acrylic material with the acrylic hardening coating according to any one of claims 1 - 7 on the surface of the acrylic material, and then cure it under light to form a hardening coating on the surface of the acrylic material to obtain an acrylic product.

Images