A photocured polyurethane acrylate coating

Abstract

The present application relates to a kind of photocuring polyurethane acrylate coating, raw material component is according to 100% mass, including: polyurethane acrylate prepolymer 30~36%, active diluent 5~12%, polyethylene glycol 0.1~0.5%, photoinitiator 1~2%, leveling agent 0.1~1%, the rest is solvent;The active diluent is composed of six functional degree acrylate monomer and double functional degree acrylate monomer.The present application uses six functional degree and double functional degree acrylate compound as active diluent, improves coating crosslinking degree;While introducing polyethylene glycol reduces the friction coefficient of coating surface, through the synergistic effect of body crosslinking enhancement and interface lubrication friction reduction, effectively improves the friction resistance of coating.It is tested that the coating of the present application has no obvious scratch after 0000# steel wire reciprocating friction 3000 times under the condition of 1000g load.

Description

Technical Field

[0001] This invention relates to the field of photocurable coating technology, and more particularly to a photocurable polyurethane acrylate coating. Background Technology

[0002] Polyurethane acrylate photocurable coatings are widely used in photovoltaic module front panels, automotive displays, AR / VR optical components, and touch screens due to their fast curing speed and good optical transparency.

[0003] However, the limited crosslinking density of pure polyurethane acrylate systems after curing results in insufficient abrasion resistance, making it difficult to meet the abrasion resistance requirements of high-end optical applications for long-term service. Currently, the mainstream method to improve the abrasion resistance of polyurethane acrylate coatings is to introduce inorganic nanoparticles (such as nano-silica, nano-alumina, etc.) as reinforcing fillers. However, the large polarity difference between inorganic nanoparticles and organic resin matrices leads to poor interfacial compatibility, making them prone to aggregation and phase separation, which in turn induces light scattering, resulting in increased coating haze and decreased light transmittance.

[0004] Therefore, it is necessary to further improve the existing polyurethane acrylate photocurable coatings. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a photocurable polyurethane acrylate coating.

[0006] The technical solution adopted in this invention is as follows: This invention provides a photocurable polyurethane acrylate coating, wherein the raw material components, by weight (100%), include: The composition includes 30-36% polyurethane acrylate prepolymer, 5-12% reactive diluent, 0.1-0.5% polyethylene glycol, 1-2% photoinitiator, 0.1-1% leveling agent, and the balance being solvent. The reactive diluent is composed of hexafunctional acrylate monomers and difunctional acrylate monomers.

[0007] Preferably, the molecular weight of the polyurethane acrylate prepolymer is 1000~6000.

[0008] Preferably, the mass ratio of the hexafunctional acrylate monomer to the difunctional acrylate monomer is 1:1 to 2:1.

[0009] Preferably, the hexafunctional acrylate monomer is dipentaerythritol hexaacrylate.

[0010] Preferably, the bifunctional acrylate monomer is 1,6-hexanediol diacrylate.

[0011] Preferably, the molecular weight of the polyethylene glycol is 400-600.

[0012] Preferably, the solvent is selected from at least one of alcohol ether solvents, ester solvents, and alcohol solvents.

[0013] Another aspect of the present invention provides a method for preparing a photocurable polyurethane acrylate coating as described in any of the above technical solutions, comprising the following steps: mixing each raw material component under light-protected conditions and stirring evenly to obtain a coating; applying the coating to the surface of a substrate and sequentially pre-drying and curing with ultraviolet light to obtain the photocurable polyurethane acrylate coating.

[0014] The beneficial effects of this invention are: (1) This invention uses a combination of hexafunctional and difunctional acrylates as an active diluent to improve the crosslinking degree of the coating; at the same time, polyethylene glycol is introduced to reduce the surface friction coefficient of the coating. Through the synergistic effect of bulk crosslinking enhancement and interfacial lubrication and friction reduction, the wear resistance of the coating is effectively improved. According to the test, the coating of this invention showed no obvious scratches after being rubbed 3000 times with 0000# steel wool under a 1000g load.

[0015] (2) The raw material components of the present invention have good compatibility, avoiding the problems of agglomeration and phase separation that are easy to occur in conventional inorganic nanoparticle modification. The coating has good transparency and the light transmittance can reach more than 93%.

[0016] (3) The preparation method of the present invention is simple and easy to scale up for industrial production. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a photocurable polyurethane acrylate coating, wherein the raw material components, by weight (100%), include: The composition includes 30-36% polyurethane acrylate prepolymer, 5-12% reactive diluent, 0.1-0.5% polyethylene glycol, 1-2% photoinitiator, 0.1-1% leveling agent, and the balance being solvent. The reactive diluent is composed of hexafunctional acrylate monomers and difunctional acrylate monomers.

[0019] This invention introduces, on the one hand, an active diluent composed of hexafunctional and difunctional acrylate monomers. During photocuring, this diluent undergoes free radical copolymerization with the polyurethane acrylate prepolymer, constructing a three-dimensional network structure with high cross-linking density. The hexafunctional acrylate monomers provide high-density cross-linking points, increasing coating hardness, while the difunctional acrylate monomers act as chain extenders, increasing the spacing between cross-linking points and providing sufficient space for chain segment movement within the cross-linked network, thus dispersing and buffering frictional shear stress. On the other hand, polyethylene glycol is introduced as a friction-reducing agent. In the cured coating, it reduces the surface friction coefficient, minimizing scratch damage to the coating surface caused by frictional resistance. Through the synergistic effect of bulk structural enhancement and interfacial lubrication and friction reduction, both agents jointly improve the coating's friction resistance.

[0020] In a preferred embodiment, the molecular weight of the polyurethane acrylate prepolymer is 1000-6000. For example, the molecular weight of the polyurethane acrylate prepolymer can be 1000, 2000, 3000, 4000, 5000, 6000, etc.

[0021] In a preferred embodiment, the mass ratio of hexafunctional acrylate monomer to difunctional acrylate monomer is 1:1 to 2:1. The present invention selects the above-mentioned mass ratio of hexafunctional and difunctional acrylate monomers for compounding, which ensures that the coating has sufficient crosslinking density and hardness to improve abrasion resistance, while avoiding problems such as coating embrittlement caused by excessive crosslinking.

[0022] In a preferred embodiment, the hexafunctional acrylate monomer is dipentaerythritol hexaacrylate. The present invention selects dipentaerythritol hexaacrylate as the hexafunctional acrylate monomer because it has high crosslinking efficiency, which is beneficial for improving the density of the crosslinked network and the hardness of the coating, thereby enhancing the abrasion resistance of the coating.

[0023] In a preferred embodiment, the difunctional acrylate monomer is 1,6-hexanediol diacrylate. This invention selects 1,6-hexanediol diacrylate as the difunctional acrylate monomer, which introduces flexible segments between crosslinking points, effectively buffering frictional shear stress while maintaining coating toughness.

[0024] In a preferred embodiment, the molecular weight of the polyethylene glycol is 400-600. This invention uses low molecular weight polyethylene glycol, which effectively reduces the surface friction coefficient of the coating and has good compatibility with other raw material components such as polyurethane acrylate prepolymers, without adversely affecting the optical properties of the coating. For example, the molecular weight of the polyethylene glycol can be 400, 450, 500, 550, 600, etc.

[0025] In a preferred embodiment, the solvent is selected from at least one of alcohol ether solvents, ester solvents, and alcohol solvents. For example, the solvent may be propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl acetate isopropanol, etc. Furthermore, the present invention does not particularly limit the photoinitiator and leveling agent; for example, the photoinitiator may be photoinitiator 1173, photoinitiator 184, etc.; and the leveling agent may be BYK-333, BYK-354, etc.

[0026] Another aspect of the present invention provides a method for preparing a photocurable polyurethane acrylate coating as described in any of the above technical solutions, comprising the following steps: mixing the raw material components under light-protected conditions and stirring until homogeneous to obtain a coating; applying the coating to the surface of a substrate, and sequentially subjecting it to pre-drying and ultraviolet curing to obtain a photocurable polyurethane acrylate coating. In an embodiment of the present invention, for example, the pre-drying temperature can be 70-80°C, and the pre-drying time can be 3-5 minutes; the ultraviolet curing energy can be 300-1000 mJ / cm². 2 .

[0027] The technical solutions of the present invention will be further described and explained below with reference to various embodiments, wherein the molecular weights mentioned in each embodiment are number-average molecular weights.

[0028] Example 1 A photocurable polyurethane acrylate coating, comprising the following raw material components by weight (100%): 33% polyurethane acrylate prepolymer (molecular weight 2500), 5% dipentaerythritol hexaacrylate, 5% 1,6-hexanediol diacrylate, 0.2% polyethylene glycol (molecular weight 600), 1.5% photoinitiator 1173, 0.5% leveling agent BYK-333, balance propylene glycol methyl ether.

[0029] It is prepared by the following steps: mixing the raw material components under light-protected conditions and stirring evenly to obtain a coating; applying the coating to the surface of a PC / PMMA substrate, pre-drying at 75°C for 5 minutes, and then applying 800mJ / cm 2 UV curing at high energy levels yields a UV-cured polyurethane acrylate coating.

[0030] Example 2 The difference between this embodiment and Embodiment 1 is that the raw material components are different.

[0031] A photocurable polyurethane acrylate coating, comprising the following raw material components by weight (100%): 35% polyurethane acrylate prepolymer (molecular weight 3500), 6.5% dipentaerythritol hexaacrylate, 3.5% 1,6-hexanediol diacrylate, 0.4% polyethylene glycol (molecular weight 400), 1.5% photoinitiator 1173, 0.5% leveling agent BYK-333, balance propylene glycol methyl ether.

[0032] The preparation method is the same as in Example 1.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is that only dipentaerythritol hexaacrylate is used as the reactive diluent (i.e., dipentaerythritol hexaacrylate is used to replace 1,6-hexanediol diacrylate in an equal amount), while the other steps remain unchanged.

[0034] Comparative Example 2 The difference between this comparative example and Example 1 is that only 1,6-hexanediol diacrylate is used as the reactive diluent (i.e., 1,6-hexanediol diacrylate is used to replace dipentaerythritol hexaacrylate in an equal amount), while the other steps remain unchanged.

[0035] Comparative Example 3 The difference between this comparative example and Example 1 is that tripropylene glycol diacrylate is used in an equal amount to replace 1,6-hexanediol diacrylate, while the other steps remain unchanged.

[0036] Comparative Example 4 The difference between this comparative example and Example 1 is that glycerol is used in an equal amount instead of polyethylene glycol. The remaining steps remain unchanged.

[0037] Comparative Example 5 The difference between this comparative example and Example 1 is that the molecular weight of polyethylene glycol was adjusted from 600 to 1000. The remaining steps remain unchanged.

[0038] The coatings obtained in Examples 1-2 and Comparative Examples 1-5 were subjected to performance tests.

[0039] Test method: (1) Abrasion resistance test: The cured coating sample was placed on a horizontal platform and rubbed against the sample surface with 0000# steel wool under a load of 1000g (stroke of about 50mm). After 2000 and 3000 times respectively, the number of scratches on the sample surface was counted. The abrasion resistance was evaluated according to the following scratch number standard: <5 scratches is excellent, 5~10 scratches is good, and >10 scratches is poor.

[0040] (2) Transmittance test: The transmittance was measured using a UV-Vis spectrophotometer, with the transmittance at 550 nm as the standard.

[0041] Table 1

[0042] Table 1 shows that the polyurethane acrylate photocurable coating prepared in the embodiments of the present invention has excellent abrasion resistance and light transmittance. Comparative Examples 1-3 show that using acrylates with a single functionality, or blends of other high- and low-functionality acrylates as reactive diluents, all result in varying degrees of decrease in the abrasion resistance of the coating. Comparative Examples 4-5 show that using polyethylene glycol with a specific molecular weight can better synergize with the crosslinking network to exert a friction-reducing effect.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photocurable polyurethane acrylate coating, characterized in that, The raw material components, by 100% mass, include: The composition includes 30-36% polyurethane acrylate prepolymer, 5-12% reactive diluent, 0.1-0.5% polyethylene glycol, 1-2% photoinitiator, 0.1-1% leveling agent, and the balance being solvent. The reactive diluent is composed of hexafunctional acrylate monomers and difunctional acrylate monomers.

2. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The molecular weight of the polyurethane acrylate prepolymer is 1000~6000.

3. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The mass ratio of the hexafunctional acrylate monomer to the difunctional acrylate monomer is 1:1 to 2:

1.

4. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The hexafunctional acrylate monomer is dipentaerythritol hexaacrylate.

5. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The bifunctional acrylate monomer is 1,6-hexanediol diacrylate.

6. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The molecular weight of the polyethylene glycol is 400-600.

7. The photocurable polyurethane acrylate coating as described in claim 1, characterized in that, The solvent is selected from at least one of alcohol ether solvents, ester solvents, and alcohol solvents.

8. A method for preparing a photocurable polyurethane acrylate coating as described in any one of claims 1-7, characterized in that, Includes the following steps: The raw material components are mixed and stirred evenly under light-protected conditions to obtain a coating; the coating is applied to the surface of a substrate and then pre-dried and cured under ultraviolet light to obtain the light-cured polyurethane acrylate coating.

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