Low-brittleness and high-wear-resistant overprint varnish and preparation method thereof

Abstract

The present application relates to the technical field of photocurable coatings, and specifically discloses a low-brittleness, high-wear-resistant overprint varnish and its preparation method. A low-brittleness, high-wear-resistant overprint varnish comprises the following components in parts by weight: 5-10 parts of hexafunctional aliphatic polyurethane acrylate; 15-20 parts of decafunctional aliphatic polyurethane acrylate; 5-8 parts of trifunctional aliphatic polyurethane acrylate; 0.5-1 parts of organosilicon-modified acrylate; 13-22 parts of mixed monomer; 2.5-4 parts of photoinitiator; and 33-45 parts of solvent. The low-brittleness, high-wear-resistant overprint varnish of the present application is compounded with hexafunctional, decafunctional, and trifunctional polyurethane acrylates, and is not easy to be brittle. At the same time, it is compounded with organosilicon-modified acrylate, which gives the coating a long-lasting, stable and smooth property, thereby improving wear resistance. In the paper tape wear test under the condition of 175g force, the coating is still not worn out after 500 rounds of friction.

Description

Technical Field

[0001] The present application relates to the technical field of light-curing coatings, and more specifically, to a low-brittleness and high-wear-resistant overprint varnish and a preparation method thereof. Background Art

[0002] UV-curable coatings, also known as photosensitive coatings, use ultraviolet light as a curing energy source, rapidly curing to form a film on substrates such as paper, plastic, leather, and wood without heating. Clearcoat, commonly known as varnish, is frequently used in model making to enhance the gloss of finished products. However, clearcoat has a wide range of applications, including automotive and exterior wall coatings. It can also be used to protect cosmetic packaging.

[0003] Clear coating generally uses polyurethane acrylate as the main resin. By compounding polyurethane acrylates with different functionalities, coatings with different physical properties can be obtained. For example, when high-functionality polyurethane acrylate is used, the hardness of the coating will be improved, and it will be less likely to be scratched or worn when subjected to external friction, thereby also improving the wear resistance of the coating.

[0004] At present, when using decafunctional polyurethane acrylate, the coating hardness can reach 3H. Although it has excellent wear resistance, the coating is prone to cracking. Summary of the Invention

[0005] In order to reduce the hardness of the coating while improving the wear resistance, the present application provides a low-brittleness and high-wear-resistant topcoat varnish and a preparation method thereof.

[0006] In a first aspect, the present application provides a low-brittleness, high-wear-resistant overprint varnish, which adopts the following technical solution:

[0007] A low-brittleness and high-wear-resistant overprint varnish comprising the following components in parts by weight:

[0008] 5-10 parts of hexafunctional aliphatic polyurethane acrylate;

[0009] 15-20 parts of decafunctional aliphatic polyurethane acrylate;

[0010] 5-8 parts of trifunctional aliphatic polyurethane acrylate;

[0011] 0.5-1 part of silicone modified acrylate;

[0012] 13-22 parts of mixed monomers;

[0013] 2.5-4 parts of photoinitiator;

[0014] 33-45 parts of solvent.

[0015] By adopting the above technical solution: hexafunctional polyurethane provides leveling, fullness and glossiness; decafunctional polyurethane provides toughness and has the advantages of good wear resistance, high hardness and fast reaction speed, but it is easy to crack after film formation, so trifunctional polyurethane is compounded to improve the brittleness problem and reduce the cracking problem of the coating. It is further compounded with silicone modified acrylate, which can participate in the cross-linking and curing, so that the coating surface has a long-lasting, stable and smooth effect, and improves the wear resistance by reducing the friction coefficient. Through the compounding of the above substances, not only the problem of brittleness of the coating due to excessive hardness is improved, but also the wear resistance is good. When used as RCA paper tape wear resistance, it can reach the test standard of rubbing more than 500 times without being worn under a force of 175g.

[0016] Optionally, the photoinitiator is a mixture of photoinitiator 184 and photoinitiator TPO.

[0017] By adopting the above technical solution: using a photoinitiator combination of 184 and TPO, the coating can absorb light in different bands and achieve rapid curing.

[0018] Optionally, the solvent consists of ethyl ester, butyl ester and butyl ether.

[0019] By adopting the above technical solution: the above three compounded solvent combination fully dissolves each component, so that the coating components can be fully mixed.

[0020] Optionally, the mixed monomer includes dipentaerythritol hexaacrylate and trimethylolpropane triacrylate.

[0021] By adopting the above technical solution: dipentaerythritol hexaacrylate has a fast reaction speed and requires low curing energy, and the combination with decafunctional polyurethane ensures the hardness of the paint film, trimethylolpropane triacrylate provides basic curing conditions, and the viscosity can be adjusted to facilitate coating construction.

[0022] Optionally, the mixed monomer includes the following components in parts by weight:

[0023] 3-7 parts of dipentaerythritol hexaacrylate;

[0024] 10-15 parts of trimethylolpropane triacrylate.

[0025] By adopting the above technical solution: when the amounts of the two are within the above ranges, the curing speed is fast and the construction is convenient.

[0026] Optionally, the preparation method of the organosilicon-modified acrylate is:

[0027] adding an emulsifier to water and dispersing the water to obtain an aqueous phase;

[0028] The oily liquid, the acrylate monomer, the copolymerized silicone monomer, and the grafted silicone monomer are blended and dispersed to obtain an oil phase;

[0029] The aqueous phase and the oil phase are mixed and dispersed, the temperature is increased, an initiator is added, and the reaction is carried out at the temperature to obtain the product.

[0030] By adopting the above technical solution: Since the chain length of the silicone side chain is relatively short, once it is bonded to the acrylate main chain, it will be "covered" by other side chains, and it is also easily "buried" by the acrylate molecules and difficult to stretch and migrate to the surface of the paint film, thereby affecting the effect of silicone modification and the smoothness of the coating.

[0031] The organosilicon-modified acrylate of the present application is prepared by first copolymerizing an organosilicon monomer with an acrylate monomer to form siloxane active grafting points, and then grafting and cross-linking reactions are carried out with a grafted organosilicon monomer through these active grafting points. The organosilicon-modified acrylate molecules thus obtained have a comb-like structure. After film formation, the silicon-containing side chains can be extended, thereby better improving the performance of the film.

[0032] Compared with the 500 wear-resistant circles of the coating when using commercially available silicone acrylate, the silicone-modified acrylate of the present application can increase the wear-resistant circles of the coating to more than 600 circles, and the coating has better wear resistance.

[0033] Optionally, the weight ratio of the acrylate monomer, the copolymerized silicone monomer, and the grafted silicone monomer is 1:1.3-1.7:10-30.

[0034] Optionally, the initiator includes azobisisobutyronitrile and an organic peroxide; and the aqueous phase further includes methacrylated hyaluronic acid.

[0035] The above technical solution demonstrates that when using azobisisobutyl cyanide alone as the initiator, the system's cohesion rate can reach as high as 4.8%, which can lead to polymer chain entanglement and limited improvement in the coating's smoothness. Therefore, the addition of methacrylated hyaluronic acid and the use of a copolymerized organosilicon as a polymerizing unit to copolymerize with the methacrylated hyaluronic acid achieves a certain degree of deformation, creating sufficient internal space in the system, thereby reducing chain entanglement and further improving the coating's surface properties.

[0036] By adding methacrylated hyaluronic acid to silicone-modified acrylate, the number of wear-resistant circles of the coating increases by more than 150 circles compared with before the addition, and the wear resistance of the coating is significantly improved.

[0037] Optionally, the weight ratio of the added amount of the methacryloyl hyaluronic acid to the acrylate monomer is 0.05-0.07:1.

[0038] By adopting the above technical solution: when the added amount of methacryloyl hyaluronic acid is within the above range, the wear resistance of the prepared coating is optimal.

[0039] In a second aspect, the present application provides a method for preparing a low-brittleness, high-wear-resistant overprint varnish, which adopts the following technical solution:

[0040] A method for preparing a low-brittleness and high-wear-resistant overprint varnish comprises the following steps:

[0041] S1. Blending hexafunctional aliphatic polyurethane acrylate, decafunctional aliphatic polyurethane acrylate, trifunctional aliphatic polyurethane acrylate, and organosilicon-modified acrylate to obtain a mixture A;

[0042] S2, adding the mixed monomer and the photoinitiator to the solvent, blending, and obtaining a mixture B;

[0043] S3. Blend mixture A and mixture B to obtain.

[0044] By adopting the above technical solution: there are fewer steps, the process is simple and efficient, which is conducive to the industrial scale preparation of coatings, and the prepared coatings have excellent wear resistance and a hardness of 2H, which is relatively moderate, and there is no problem of brittle cracking due to excessive hardness.

[0045] In summary, this application has the following beneficial effects:

[0046] 1. This application uses hexafunctional, decafunctional, and trifunctional polyurethane acrylates for compounding. The trifunctional polyurethane acrylate is used to improve the brittleness problem. At the same time, silicone-modified acrylate is compounded to give the coating a long-lasting, stable and smooth finish, thereby improving wear resistance.

[0047] 2. The organosilicon-modified acrylate of the present application is first copolymerized with an acrylate monomer to form siloxane active grafting points, and then grafted with a grafted organosilicon monomer to undergo grafting and cross-linking reactions through these active grafting points. The organosilicon-modified acrylate molecules thus obtained have a comb-like structure. After film formation, the silicon-containing side chains can be extended, thereby effectively reducing the friction coefficient of the coating and improving wear resistance.

[0048] 3. Methacryloyl hyaluronic acid is also added during the preparation of the silicone-modified acrylate of the present application, and copolymerized silicone is used as a polymerization unit to copolymerize with methacryloyl hyaluronic acid, thereby achieving a certain degree of deformation, so that the system has sufficient internal space, thereby reducing chain entanglement and better improving the wear resistance of the coating. DETAILED DESCRIPTION

[0049] The present application is further described in detail below with reference to the examples. The sources of the components are as follows, except for the following special instructions, the components are commercially available:

[0050] Polyoxyethylene octylphenol ether, purchased from Shandong Jinli Chemical Co., Ltd., product name OP-10;

[0051] Methacryloyl hyaluronic acid was obtained from Xi'an Qiyue Biotechnology Co., Ltd.

[0052] Hexafunctional aliphatic polyurethane acrylate, purchased from Dongguan Jingshang New Materials Development Co., Ltd., model UV-6042;

[0053] Decafunctional aliphatic polyurethane acrylate, purchased from Allnex Resins (China) Co., Ltd., Ebecryl225;

[0054] Trifunctional aliphatic polyurethane acrylate, purchased from Jining Tangyi Chemical Co., Ltd., YC3165;

[0055] The organosilicon-modified acrylates of Examples 1-3 were purchased from Dongguan Huazhiyuan Chemical Co., Ltd., model 3550.

[0056] Preparation Example 1

[0057] A silicone-modified acrylate is prepared by the following steps:

[0058] Emulsifiers (1.5 kg sodium lauryl sulfate and 0.5 kg polyoxyethylene octylphenol ether) were added to 80 kg water, and the mixture was stirred at 500 rpm for 15 min to obtain an aqueous phase;

[0059] 20 kg of oily liquid (isohexadecane), 1 kg of acrylate monomer (methacrylic acid), 1.5 kg of copolymerized silicone monomer (methylphenyldimethoxysilane), and 10 kg of grafted silicone monomer (dimethyldimethoxysilane) were blended and stirred at 1000 rpm for 30 minutes to obtain an oil phase;

[0060] 8 kg of aqueous phase and 2 kg of oil phase were blended, stirred at 1000 rpm for 20 min, ultrasonically dispersed at 600 W for 10 min, stirred for 10 min under nitrogen, heated to 60°C, added with 0.03 kg of initiator (azobisisobutyronitrile), and kept warm for 200 min to obtain the product.

[0061] Preparation Example 2-3

[0062] A silicone-modified acrylate is different from Preparation Example 1 in that the amounts of copolymerized silicone monomer and grafted silicone monomer are different, as follows:

[0063] In Preparation Example 2, the weight ratio of the added amount of the copolymerized silicone monomer and the grafted silicone monomer to the acrylate monomer is 1.3:20:1.

[0064] In Preparation Example 3, the weight ratio of the added amount of the copolymerized silicone monomer and the grafted silicone monomer to the acrylate monomer is 1.7:30:1.

[0065] Preparation Example 4

[0066] A silicone-modified acrylate is prepared by the following steps:

[0067] To 80 kg of water, an emulsifier (1.5 kg of sodium lauryl sulfate, 0.5 kg of polyoxyethylene octylphenol ether) and 0.05 kg of methacryloyl hyaluronic acid were added, and the mixture was stirred at 500 rpm for 15 minutes to obtain an aqueous phase;

[0068] 20 kg of oily liquid (isohexadecane), 1 kg of acrylate monomer (methacrylic acid), 1.5 kg of copolymerized silicone monomer (methylphenyldimethoxysilane), and 10 kg of grafted silicone monomer (dimethyldimethoxysilane) were blended and stirred at 1000 rpm for 30 minutes to obtain an oil phase;

[0069] 8 kg of aqueous phase and 2 kg of oil phase were blended, stirred at 1000 rpm for 20 min, ultrasonically dispersed at 600 W for 10 min, stirred for 10 min under nitrogen, heated to 60 ° C and added with initiator (0.02 kg of azobisisobutyronitrile and 0.16 kg of 6 wt% aqueous ammonium persulfate solution), and kept warm for 200 min to obtain the product.

[0070] Preparation Example 5-6

[0071] A silicone-modified acrylate, which differs from Preparation Example 4 in that the amount of methacryloyl hyaluronic acid added is different, specifically as follows:

[0072] In Preparation Example 5, the weight ratio of the added amount of methacryloyl hyaluronic acid to the acrylate monomer is 0.06:1.

[0073] In Preparation Example 6, the weight ratio of the added amount of methacryloyl hyaluronic acid to the acrylate monomer is 0.07:1.

[0074] Examples 1-3, Comparative Examples 1-3

[0075] A low-brittle, high-wear-resistant overprint varnish, the components and their corresponding weights of which are shown in Table 1, is prepared by the following steps:

[0076] S1. Blending hexafunctional aliphatic polyurethane acrylate, decafunctional aliphatic polyurethane acrylate, trifunctional aliphatic polyurethane acrylate, and silicone-modified acrylate, and stirring at 1000 rpm for 30 min to obtain a mixture A.

[0077] S2. Adding mixed monomers (dipentaerythritol hexaacrylate, trimethylolpropane triacrylate) and photoinitiator (184, TPO) to the solvent (ethyl ester), blending, and stirring at 1000 rpm for 10 min to obtain mixture B;

[0078] S3. Blend mixture A, mixture B, butyl ester and butyl ether, and stir at 800 rpm for 15 min to obtain the product.

[0079] Table 1 Components and their weights (kg) in Examples 1-3 and Comparative Examples 1-3

[0080]

[0081]

[0082] Examples 4-9

[0083] A low-brittle, high-wear-resistant overprint varnish is prepared. The difference from Example 2 is that the organosilicon-modified acrylate is prepared according to the Preparation Example. The specific usage is shown in Table 2 below, but the amount remains unchanged.

[0084] Table 2 Usage of silicone modified acrylate in Examples 4-9

[0085] Example 4 5 6 7 8 9 Preparation Example of Silicone-Modified Acrylate 1 2 3 4 5 6

[0086] Performance testing

[0087] The varnish prepared in the examples and comparative examples was coated on a plate and cured to obtain a sample. The preparation method of the sample can refer to the following:

[0088] The varnish was sprayed on the PC board with a thickness of 15 μm, dried at 50 ° C for 3 min, and then irradiated with a high-pressure mercury lamp with a line power of 120 W / cm, a wavelength of 350 nm, and a radiation dose of 1000 mJ / cm 2 Dry and cure for 15 seconds.

[0089] The samples were subjected to the following performance tests, and the test results are recorded in Table 3.

[0090] Detection method

[0091] 1. Wear resistance test: The sprayed sample is fixed on a paper tape abrasion tester, and a 175g force vertical friction test is set. The test number of laps is set to 1000. It is required to pause and observe the appearance at 300 laps. After 300 laps, check every 50 laps. During the inspection, use a 60x luminous magnifying glass to observe whether the coating on the surface of the sample is worn. Record the maximum number of laps when it is worn. If the coating is observed to be worn at 450 laps, the number of laps is recorded as 400.

[0092] 2. Hardness test: Test according to GB / T 6739-1986.

[0093] 3. Adhesion test: Test according to GB / T 9286-1998.

[0094] Table 3 Performance test results

[0095] project Wear resistance (circle) hardness Adhesion grade (grade) Example 1 500 2H Level 1 Example 2 550 2H Level 1 Example 3 500 2H Level 1 Example 4 600 2H Level 1 Example 5 650 2H Level 1 Example 6 600 2H Level 1 Example 7 800 2H Level 1 Example 8 850 2H Level 1 Example 9 850 2H Level 1 Comparative Example 1 600 3H Level 2 Comparative Example 2 350 H Level 1 Comparative Example 3 400 H Level 1

[0096] Referring to Table 3, Example 1 employs hexafunctional, decafunctional, and trifunctional polyurethane acrylates in combination with a silicone-modified acrylate. The resulting coating has a hardness of 2H, is resistant to cracking, and exhibits wear resistance of 500 cycles without wear. Comparative Examples 1-3 differ from Example 2 in that they lack either the trifunctional or decafunctional polyurethane acrylate or the silicone-modified acrylate. Consequently, the resulting coatings exhibit problems such as excessive hardness, brittle cracking, low hardness, and poor wear resistance, or suitable hardness but requiring improved wear resistance.

[0097] The difference between Examples 4-6 and Example 2 is that the silicone-modified acrylate is prepared by the preparation example of the present application. In the preparation process of the present application, the silicone monomer is first copolymerized with the acrylate monomer to form a siloxane active grafting point, and then the grafted silicone monomer is grafted and cross-linked through these active grafting points. The silicone-modified acrylate molecules prepared in this way have a comb-like structure. After film formation, the silicon-containing side chains can be extended, which better improves the smoothness of the coating and increases the number of wear-resistant circles to more than 600 circles, but the improvement effect is not obvious, which may be due to the existence of chain entanglement.

[0098] The difference between Examples 7-9 and Example 5 is that methacrylated hyaluronic acid is added during the preparation of the silicone-modified acrylate. The resulting coatings can survive more than 800 cycles without being worn, further improving their abrasion resistance. The possible reasons for this are:

[0099] By using copolymerized silicone as a polymerization unit and copolymerizing with methacryloyl hyaluronic acid, a certain degree of deformation is achieved, so that the system has sufficient internal space, thereby reducing chain entanglement, and allowing the silicone-modified acrylate to better improve the smoothness of the coating and better wear resistance.

[0100] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low-brittleness, high-wear-resistant overprint varnish, characterized in that: The composition comprises the following components in parts by weight: 5-10 parts of hexafunctional aliphatic polyurethane acrylate; 15-20 parts of decafunctional aliphatic polyurethane acrylate; 5-8 parts of trifunctional aliphatic polyurethane acrylate; 0.5-1 part of silicone modified acrylate; 13-22 parts of mixed monomers; 2.5-4 parts of photoinitiator; 33-45 parts of solvent; The preparation method of the organosilicon-modified acrylate is as follows: adding an emulsifier and methacryloyl hyaluronic acid to water and dispersing the mixture to obtain an aqueous phase; The oily liquid, the acrylate monomer, the copolymerized silicone monomer, and the grafted silicone monomer are blended and dispersed to obtain an oil phase; The aqueous phase and the oil phase are mixed and dispersed, the temperature is increased, an initiator is added, and the temperature is kept to react to obtain the product; The initiator includes azobisisobutyronitrile and an organic peroxide; The weight ratio of the acrylate monomer, copolymerized silicone monomer, and grafted silicone monomer is 1:1.3-1.7:10-30; The weight ratio of the added amount of the methacryloyl hyaluronic acid to the acrylate monomer is 0.05-0.07:1; The copolymerized organic silicon monomer is methylphenyldimethoxysilane, and the grafted organic silicon monomer is dimethyldimethoxysilane.

2. The low-brittleness, high-wear-resistant overprint varnish according to claim 1, characterized in that: The photoinitiator is a mixture of photoinitiator 184 and photoinitiator TPO.

3. The low-brittleness and high-wear-resistant overprint varnish according to claim 1, characterized in that: The solvent consists of ethyl ester, butyl ester and butyl ether.

4. The low-brittleness and high-wear-resistant overprint varnish according to claim 1, characterized in that: The mixed monomers include dipentaerythritol hexaacrylate and trimethylolpropane triacrylate.

5. The low-brittleness and high-wear-resistant overprint varnish according to claim 4, characterized in that: The mixed monomers include the following components in parts by weight: 3-7 parts of dipentaerythritol hexaacrylate; 10-15 parts of trimethylolpropane triacrylate.

6. A method for preparing the low-brittleness and high-wear-resistant overprint varnish according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Blending hexafunctional aliphatic polyurethane acrylate, decafunctional aliphatic polyurethane acrylate, trifunctional aliphatic polyurethane acrylate, and organosilicon-modified acrylate to obtain a mixture A; S2, adding the mixed monomer and the photoinitiator to the solvent, blending, and obtaining a mixture B; S3. Blend mixture A and mixture B to obtain.

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