Hydrophobic ultraviolet curing coating composition and application thereof

Abstract

The invention provides a hydrophobic ultraviolet curing coating composition and application thereof. The hydrophobic ultraviolet curing coating composition comprises the following components in parts by mass: 50-70 parts of an epoxy acrylic resin compound, 10-25 parts of modified silicon dioxide, 2-8 parts of a photoinitiator, 5-15 parts of an acrylic monomer, 1-7 parts of an auxiliary agent and 20-60 parts of a solvent, the epoxy acrylic resin compound is a mixture of modified epoxy acrylic resin and epoxy acrylic resin. The hydrophobic ultraviolet curing coating composition provided by the invention is short in curing time and easy to cure, and a paint film formed after curing is better in adhesive force and higher in hardness and water contact angle under the condition of keeping good artificial aging resistance, so that the prepared paint film has better hydrophobicity and scratch resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a hydrophobic ultraviolet (UV) curable coating composition and its application. Background Art

[0002] Ultraviolet (UV) curable coatings use ultraviolet light as the energy source for coating curing, and have the advantages of fast curing, low curing temperature, less pollution, energy saving and high efficiency. They are a new generation of green chemical products. UV curable coatings can be divided into free radical type and cationic type according to the UV curing mechanism. Among them, cationic UV curing generates positive ion active centers after UV irradiation and undergoes ring-opening polymerization. During curing, it has the advantages of small volume shrinkage rate, good adhesion, and no inhibition effect of oxygen on cationic curing. However, it also has the problems of slow curing speed, not being suitable for products requiring rapid curing, and the problem that products with relatively large thickness requirements cannot be formed in one step. Free radical UV curing undergoes free radical copolymerization of carbon-carbon double bonds under UV irradiation, and has the advantages of high gloss and good weather resistance, and is widely used in fields such as printing.

[0003] However, free radical UV curing also has defects such as poor adhesion, hardness, abrasion resistance, scratch resistance and hydrophobicity during curing. In order to avoid the defects existing in free radical UV curing, the patent with the patent number "CN104910757B" provides a heat-resistant UV curable coating. The use of nano-silica, nano-titanium dioxide and nano-aluminum oxide in the coating can improve the hydrophobicity, heat resistance and mechanical properties of the coating, but the improvement of the hydrophobicity of the UV curable coating is relatively small, and the hardness is poor.

[0004] Aiming at the problems existing in the existing UV curable coatings, how to provide a hydrophobic UV curable coating composition with short curing time, good resistance to artificial aging, good hydrophobicity and high hardness is an urgent problem to be solved by the present invention. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydrophobic UV curable coating composition and its application, so as to solve the problem of how to provide a hydrophobic UV curable coating composition with short curing time, good resistance to artificial aging, good hydrophobicity and high hardness proposed in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: On the one hand, the present invention provides a hydrophobic UV curable coating composition, and the hydrophobic UV curable coating composition includes the following components in parts by mass: 50 - 70 parts by mass of an epoxy acrylate resin composite, 10 - 25 parts by mass of modified silica, 2 - 8 parts by mass of a photoinitiator, 5 - 15 parts by mass of an acrylic monomer, 1 - 7 parts by mass of an auxiliary agent, and 20 - 60 parts by mass of a solvent;

[0007] The epoxy acrylate resin complex is a mixture of modified epoxy acrylate resin and epoxy acrylate resin.

[0008] In some embodiments of the present invention, in order to improve the hardness of the film formed by the hydrophobic ultraviolet-curable coating composition, preferably, the epoxy acrylate resin complex contains epoxy acrylate resin.

[0009] In some embodiments of the present invention, in order to improve the hydrophobicity of the film formed by the hydrophobic ultraviolet-curable coating composition, preferably, the epoxy acrylate resin complex contains modified epoxy acrylate resin.

[0010] In some embodiments of the present invention, in order to ensure that the film formed by the hydrophobic ultraviolet-curable coating composition has good hardness and hydrophobicity, preferably, the epoxy acrylate resin complex contains modified epoxy acrylate resin and epoxy acrylate resin.

[0011] In some embodiments of the present invention, in order to ensure that the film formed by the hydrophobic ultraviolet-curable coating composition has better hardness and hydrophobicity, the mass ratio of the modified epoxy acrylate resin to the epoxy acrylate resin is 1:(1 - 5); preferably, the mass ratio of the modified epoxy acrylate resin to the epoxy acrylate resin is 1:(2 - 4).

[0012] In some embodiments of the present invention, in order to shorten the curing time of the hydrophobic ultraviolet-curable coating composition, preferably, the modified silica is obtained by the following preparation method:

[0013] (2.1) Dissolve cetyltrimethylammonium bromide in a mixed solution containing ammonia water, then add tetraethyl orthosilicate while stirring, and then carry out a heating reaction. After the reaction is completed, centrifuge to obtain an intermediate product;

[0014] (2.2) Place the intermediate product obtained in step (2.1) in deionized water for ultrasonic stirring. After cooling, filtering, and washing, continue to treat it with a hydrochloric acid ethanol solution. After the treatment is completed, dry it to obtain modified silica.

[0015] In some embodiments of the present invention, in the preparation method of the modified silica, preferably, when carrying out the heating reaction in step (2.1), the temperature includes but is not limited to one of 38°C, 40°C, 42°C, 45°C, 47°C.

[0016] In some embodiments of the present invention, when preparing the modified silica, mesoporous silica is first prepared, and then the mesoporous silica is treated. The obtained modified silica not only has mesopores but also has a hollow structure, enabling substances such as epoxy acrylate resin and modified epoxy acrylate resin to easily enter the hollow structure of the silica. During long-term storage, substances such as epoxy acrylate resin and modified epoxy acrylate resin and the modified silica will not cause the modified silica to settle or aggregate due to poor compatibility, thereby making the substances such as epoxy acrylate resin and modified epoxy acrylate resin and the modified silica more uniformly distributed in the system. Moreover, the obtained modified silica has good high-temperature resistance, enabling the paint film formed after curing the hydrophobic UV-curable coating composition to still have excellent properties such as artificial aging resistance, adhesion, and hardness even after long-term storage, and at the same time can shorten the curing time during UV curing.

[0017] In some embodiments of the present invention, preferably, the preparation method of the modified epoxy acrylate resin includes the following steps:

[0018] (1.1) Add hydroxy silicone oil to the reaction vessel. After evacuating, under the condition of nitrogen gas introduction, dropwise add hexamethylene diisocyanate for reaction. After the reaction ends, an intermediate is obtained.

[0019] (1.2) Dilute the epoxy acrylate resin, heat it to 30 - 50 °C, and then dropwise add the intermediate obtained in step (1.1) for sufficient reaction. After the reaction ends, the modified epoxy acrylate resin is obtained.

[0020] In some embodiments of the present invention, during the preparation of the modified epoxy acrylate resin, an intermediate containing -NCO groups is produced by the reaction of hydroxy silicone oil and hexamethylene diisocyanate, and then the -NCO groups in the intermediate react with the -OH in the epoxy acrylate resin to graft the silicone long chain onto the epoxy acrylate resin, reducing the surface energy of the epoxy acrylate resin, thereby reducing the wettability of water droplets to the epoxy acrylate resin, increasing the surface water contact angle of the modified epoxy acrylate resin, and enabling the paint film formed after curing the hydrophobic UV-curable coating composition to have better hydrophobicity.

[0021] In some embodiments of the present invention, the particle size of the modified silica prepared in the present invention is nanoscale. When the nanoscale modified silica and the modified epoxy acrylate resin are used in combination, the surface of the obtained hydrophobic UV-curable coating composition is not flat, containing many protrusions and pits, so that water droplets cannot fill the grooves on the rough surface, and there is trapped air under the water droplets, reducing the contact area between the water droplets and the coating and expanding the interface between the water droplets and the air, making the surface of the paint film formed after curing the hydrophobic UV-curable coating composition not wetted by water, and further improving the hydrophobic performance of the paint film formed after curing the hydrophobic UV-curable coating composition.

[0022] In some embodiments of the present invention, preferably, in step (1.1), the mass ratio of the hydroxyl-terminated silicone oil to hexamethylene diisocyanate is 1:(0.9 - 1.1).

[0023] In some embodiments of the present invention, preferably, in step (1.2), the intermediate is 20 - 80% of the mass of the epoxy acrylate resin.

[0024] In some embodiments of the present invention, preferably, the photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl phenyl ketone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0025] In some embodiments of the present invention, preferably, the acrylic monomer is at least one of hydroxyethyl acrylate, isooctyl acrylate, propyl methacrylate, caprolactone acrylate, 1,6-hexanediol diacrylate, and dipropylene glycol diacrylate.

[0026] In some embodiments of the present invention, preferably, the auxiliary agent is at least one of a dispersant, an antifoaming agent, and an emulsifier.

[0027] In some embodiments of the present invention, preferably, the dispersant is at least one of polydimethylsiloxane, sodium dodecyl diphenyl ether disulfonate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, and lignosulfonate.

[0028] In some embodiments of the present invention, preferably, the antifoaming agent is at least one of polysiloxane polymers, polyether-modified dimethylpolysiloxane copolymers, and mixtures of polysiloxanes and polymers.

[0029] In some embodiments of the present invention, preferably, the emulsifier is at least one of an anionic emulsifier and a nonionic emulsifier.

[0030] In some embodiments of the present invention, preferably, the solvent is at least one of water, methanol, absolute ethanol, isopropanol, butanol, propylene glycol methyl ether, and ethylene glycol monobutyl ether.

[0031] On the other hand, the present invention also provides an application of the hydrophobic ultraviolet-curable coating composition in a brightening film and a matte film.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: The hydrophobic ultraviolet-curable coating composition provided by the present invention has a short curing time and is easy to cure. Moreover, the cured paint film has better adhesion, higher hardness and water contact angle while maintaining good resistance to artificial aging, making the obtained paint film have better hydrophobicity and scratch resistance. Detailed Embodiments

[0033] The present invention will be described below in conjunction with specific implementation embodiments. It should be noted that the following embodiments are examples of the present invention, which are only used to illustrate the present invention and not to limit the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0034] In the following embodiments, except for epoxy acrylate resin, modified epoxy acrylate resin, and modified silica, the compound monomers and related reagents used can all be purchased from the market. Among them, hydroxy silicone oil is purchased from Jinan Zhongao Chemical Co., Ltd., with the product number ZA-205; epoxy resin is purchased from Heyi New Materials (Guangzhou) Co., Ltd., with the product number HYSZ-BLSH-E51; polydimethylsiloxane is purchased from Guangzhou Xingxing Biotechnology Co., Ltd., with the model PMX-200 350cSt; nano-silica is purchased from Nanjing Baokete New Materials Co., Ltd., with the product number PST.

[0035] The preparation method of epoxy acrylate resin includes the following steps:

[0036] Add 100 parts by mass of epoxy resin and 0.1 part by mass of catalyst (the catalyst is purchased from Henan Wanyu Chemical Raw Materials Co., Ltd., with the product number 20186-6) to the reaction kettle. After heating to 90 °C, add dropwise 45 parts by mass of methacrylic acid, and then slowly heat to 105 °C and carry out heat preservation reaction. After reacting for 3 h, the reaction ends, and after purification and drying, epoxy acrylate resin is obtained.

[0037] The preparation method of modified epoxy acrylate resin includes the following steps:

[0038] (1.1) Add 50 parts by mass of hydroxy silicone oil to the reaction vessel. After evacuating for 3 h at 90 °C, cool to 60 °C, and under the condition of passing nitrogen, add dropwise 52 parts by mass of hexamethylene diisocyanate for reaction. After the reaction ends, an intermediate is obtained;

[0039] (1.2) Dilute 70 parts by mass of epoxy acrylate resin with 40 parts by mass of glycidyl methacrylate, heat to 40 °C, and then add dropwise 30 parts by mass of the intermediate obtained in step (1.1) and carry out sufficient reaction. After reacting for 8 h, modified epoxy acrylate resin is obtained.

[0040] The preparation method of modified silica includes the following steps:

[0041] (2.1) Dissolve 35 parts by mass of cetyltrimethylammonium bromide in a mixed solution of ethanol and water containing 1 mL of ammonia water (the concentration of ammonia water is 28%) (the volume of ethanol is 600 mL and the volume of water is 135 mL), and then while stirring, add 208 parts by mass of tetraethyl orthosilicate and carry out a heating reaction (the reaction temperature is 45 °C and the reaction time is 24 h). After the reaction ends, centrifuge to obtain an intermediate product;

[0042] (2.2) The intermediate product obtained in step (2.1) was placed in 150 mL of deionized water and ultrasonically stirred for 6 h. After cooling to room temperature, the product was filtered out, washed 6 times with deionized water and anhydrous ethanol respectively, and then further treated with a hydrochloric acid ethanol solution (10 mL of hydrochloric acid and 40 mL of anhydrous ethanol) (treatment temperature: 60 °C). After 3 treatments, it was dried (drying temperature: 60 °C, drying time: 4 h) to obtain modified silica.

[0043] The hydrophobic ultraviolet curable coating compositions prepared in Examples 1-5 included the following steps:

[0044] The epoxy acrylate resin complex, modified silica, photoinitiator, acrylic monomer, additive, and solvent were added to a mixer and mixed evenly to obtain a hydrophobic ultraviolet curable coating composition. Among them, the stirring speed of the mixer was 80 r / min and the stirring time was 20 min.

[0045] The hydrophobic ultraviolet curable coating composition prepared in Comparative Example 1 included the following steps:

[0046] The epoxy acrylate resin, modified silica, photoinitiator, acrylic monomer, additive, and solvent were added to a mixer and mixed evenly to obtain a hydrophobic ultraviolet curable coating composition. Among them, the stirring speed of the mixer was 80 r / min and the stirring time was 20 min.

[0047] The hydrophobic ultraviolet curable coating composition prepared in Comparative Example 2 included the following steps:

[0048] The epoxy acrylate resin complex, nano-silica, photoinitiator, acrylic monomer, additive, and solvent were added to a mixer and mixed evenly to obtain a hydrophobic ultraviolet curable coating composition. Among them, the stirring speed of the mixer was 80 r / min and the stirring time was 20 min.

[0049] The components and their contents used in Examples 1-5 and Comparative Examples 1-2 are shown in Tables 1-3:

[0050] Table 1

[0051]

[0052]

[0053] Table 2

[0054]

[0055] Table 3

[0056]

[0057]

[0058] The hydrophobic UV-curable coating compositions prepared in Examples 1-5 and Comparative Examples 1-2 were respectively printed on a polycarbonate (PC) plastic shell coated with a UV topcoat, with a printing thickness of 10 μm, left to stand at room temperature for 3 min, and then cured by ultraviolet light under a UV machine with a conveyor belt linear speed of 3.5 m / min and an energy of 1200 mJ / cm 2 to obtain printed products with a paint film on the surface. At the same time, the curing time, adhesion, hardness, water contact angle, and resistance to artificial aging of each paint film were tested, and the test methods were as follows:

[0059] Adhesion: Tested according to GB / T 9286 "Cross-Cut Test for Paints and Varnishes - Film".

[0060] Hardness: Tested according to ASTM D3363-05(2011) standard.

[0061] Water contact angle: Tested according to ASTM D5946-2017 standard.

[0062] Resistance to artificial aging: According to GB / T 1865-1997 "Artificial Weathering and Artificial Radiation Exposure of Paints and Varnishes".

[0063] The above test results are shown in Table 4, as follows:

[0064] Table 4

[0065]

[0066] From the comparison between Example 1 and Comparative Example 1, it can be seen that the use of an epoxy acrylate resin complex with a modified epoxy acrylate resin can improve the water contact angle of the prepared paint film and make the prepared paint film more hydrophobic while maintaining the adhesion, resistance to artificial aging, curing time, and hardness at appropriate levels;

[0067] From the comparison between Example 1 and Comparative Example 2, it can be seen that compared with commercially available nano-silica, the use of modified silica can shorten the curing time of the hydrophobic UV-curable coating composition, and the formed paint film after curing can improve the adhesion, hardness, and water contact angle of the prepared paint film while having better resistance to artificial aging. On the other hand, when nano-scale modified silica and modified epoxy acrylate resin are used in combination, the prepared paint film has better hydrophobicity;

[0068] From the comparison between Example 1 and Examples 4-5, it can be seen that when the mass ratio of the modified epoxy acrylate resin to the modified silica is within an appropriate range, the water contact angle of the paint film can be further improved;

[0069] It can be seen from the comparison of Examples 1-3 that the hydrophobic UV-curable coating composition prepared using the components and contents provided by the present invention has a short curing time, is easy to cure, and the film formed after curing has better adhesion, higher hardness and water contact angle while maintaining good resistance to artificial aging.

[0070] In summary, the hydrophobic UV-curable coating composition provided by the present invention has a short curing time, is easy to cure, and the film formed after curing has better adhesion, higher hardness and water contact angle while maintaining good resistance to artificial aging, making the prepared film have better hydrophobicity and scratch resistance.

[0071] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A hydrophobic ultraviolet curable coating composition, characterized in that: The hydrophobic ultraviolet-curable coating composition comprises the following components in parts by mass: 50-70 parts by mass of an epoxy acrylate resin complex, 10-25 parts by mass of modified silica, 2-8 parts by mass of a photoinitiator, 5-15 parts by mass of an acrylic monomer, 1-7 parts by mass of an auxiliary agent, and 20-60 parts by mass of a solvent; The epoxy acrylate resin complex is a mixture of a modified epoxy acrylate resin and an epoxy acrylate resin.

2. The hydrophobic ultraviolet curable coating composition according to claim 1, wherein: The mass ratio of the modified epoxy acrylate resin to the epoxy acrylate resin is 1:(1-5); preferably, the mass ratio of the modified epoxy acrylate resin to the epoxy acrylate resin is 1:(2-4).

3. The hydrophobic ultraviolet curable coating composition according to claim 1, wherein: The preparation method of the modified epoxy acrylate resin comprises the following steps: (1.1) Add hydroxy silicone oil into a reaction vessel, evacuate, and then dropwise add hexamethylene diisocyanate under a nitrogen atmosphere for reaction. After the reaction is completed, an intermediate product is obtained; (1.2) Dilute the epoxy acrylate resin, heat it to 30-50 °C, and then dropwise add the intermediate product prepared in step (1.1) for sufficient reaction. After the reaction is completed, a modified epoxy acrylate resin is obtained.

4. The hydrophobic ultraviolet curable coating composition according to claim 3, wherein: In step (1.1), the mass ratio of the hydroxy silicone oil to the hexamethylene diisocyanate is 1:(0.9-1.1).

5. The hydrophobic ultraviolet curable coating composition according to claim 3, characterized in that: In step (1.2), the intermediate product is 20-80% of the mass of the epoxy acrylate resin.

6. The hydrophobic ultraviolet curable coating composition according to claim 1, characterized in that: The preparation method of the modified silica comprises the following steps: (2.1) Dissolve cetyltrimethylammonium bromide in a mixed solution containing ammonia water, then add tetraethyl orthosilicate dropwise with stirring, and then carry out a heating reaction. After the reaction is completed, centrifuge to obtain an intermediate product; (2.2) Place the intermediate product prepared in step (2.1) in deionized water for ultrasonic stirring. After cooling, filtering, and washing, continue to treat it with a hydrochloric acid ethanol solution. After the treatment is completed, dry it to obtain modified silica.

7. The hydrophobic ultraviolet curable coating composition according to claim 1, wherein: The photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl phenyl ketone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

8. The hydrophobic ultraviolet curable coating composition according to claim 1, wherein: The acrylic monomer is at least one of hydroxyethyl acrylate, isooctyl acrylate, propyl methacrylate, caprolactone acrylate, 1,6-hexanediol diacrylate, and dipropylene glycol diacrylate.

9. The hydrophobic ultraviolet curable coating composition according to claim 1, wherein: The auxiliary agent is at least one of a dispersant, an antifoaming agent, and an emulsifier; Preferably, the dispersant is at least one of polydimethylsiloxane, sodium dodecyl diphenyl ether disulfonate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, and lignosulfonate.

10. Application of the hydrophobic ultraviolet-curable coating composition according to any one of claims 1-9 in a bright film and a matte film.

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