An environmentally friendly UV-cured coating for thin film aluminum plating process and a preparation method thereof

Abstract

The present application relates to the technical fields of UV coating, and discloses an environment-friendly UV curing coating for thin film aluminum plating process and a preparation method thereof, the present application uses polyethylene glycol diglycidyl ether, N-(4-carboxyl phenyl) phthalimide and acryloyl chloride as raw materials to prepare acrylate phthalimide polyethylene glycol containing two alkenyl groups, which is used as an active diluent to carry out a photocuring reaction with epoxy acrylate, contains a flexible polyether molecular chain, is crosslinked and solidified into an epoxy resin, has a good toughening effect, and improves the flexibility, impact resistance and bending strength of the coating. Moreover, the phthalimide structure has thermal stability, so that the coating has a good thermal decomposition temperature and heat resistance. The aluminum sheet is used as a base material, the coating has good adhesion and bonding properties, and has good practical application in the thin film aluminum plating process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of UV coating, in particular to an environment-friendly UV curing coating for thin film aluminum plating process and a preparation method thereof. BACKGROUND

[0002] Thin film aluminum plating process is to coat a very thin layer of metal aluminum on the surface of PET, polypropylene and other plastic films, thereby forming high-grade packaging materials with metallic luster, which have excellent wear resistance, folding resistance, gas barrier and other properties, and are widely used in food and drug packaging materials. However, aluminum has very active chemical properties, and the aluminum-plated film is prone to oxidation and corrosion, so it is usually necessary to coat varnish coatings such as acrylic resin and epoxy resin on the surface of the aluminum-plated film.

[0003] Epoxy acrylate is usually obtained by reacting acrylic acid and epoxy resin, and is a resin material with UV light curing, which is widely used in coatings, inks and other aspects. The traditional epoxy acrylate has poor toughness and poor impact resistance, so it needs to be toughened and modified. Patent No. CN101928508B discloses a polyethylene glycol modified epoxy acrylate coating and a preparation method thereof. Polyethylene glycol, epoxy resin and acrylic acid are reacted to obtain an epoxy acrylate with excellent adhesion, flexibility, pencil hardness and other properties. However, the thermal decomposition temperature of polyethylene glycol is relatively low, and its addition to the epoxy acrylate will affect the heat resistance of the coating. SUMMARY

[0004] The present application solves the problem of poor toughness of the epoxy acrylate UV curing coating, and improves the heat resistance of the coating, which is applied to the thin film aluminum plating process.

[0005] Technical scheme: A preparation method of an environment-friendly UV curing coating:

[0006] (1) reacting polyethylene glycol diglycidyl ether and N-(4-carboxylphenyl) phthalimide to obtain phthalimide-based polyethylene glycol; and then reacting with acryloyl chloride to obtain acrylate phthalimide polyethylene glycol.

[0007] (2) adding 68-70 parts by weight of epoxy acrylate, 5-15 parts by weight of acrylate phthalimide polyethylene glycol, 0.5-0.8 parts by weight of defoaming agent and 0.2-0.4 parts by weight of leveling agent to 18-26 parts by weight of active diluent, stirring, then adding 2.4-3.2 parts by weight of photoinitiator to obtain an environment-friendly UV curing coating; finally, spraying the coating on the surface of the substrate and performing light curing in a UV curing machine to obtain an environment-friendly UV curing coating.

[0008] Further, the active diluent is tripropyleneglycol diacrylate, dipropyleneglycol diacrylate or 1,6-hexanediol diacrylate.

[0009] Further, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0010] Further, the power of the UV curing machine is 1-1.5 kW, and the light curing time is 60-120 s.

[0011] Further, the preparation method of the acrylate phthalimide polyethylene glycol comprises:

[0012] (1) 100 parts by weight of polyethylene glycol diglycidyl ether, 96-132 parts by weight of N-(4-carboxylphenyl) phthalimide, and 7.2-8.8 parts by weight of benzyltriethylammonium chloride are added to toluene, heated to 100-110 DEG C, stirred for 6-9 h, and condensed backflow during the reaction, rotary evaporation, petroleum ether washing, product dissolution in ethanol, heating volatilization, cooling crystallization, to obtain phthalimide polyethylene glycol. The reaction formula is:

[0013]

[0014] (2) 100 parts by weight of phthalimide polyethylene glycol, 310-420 parts by weight of triethylamine are added to the solvent in an ice bath, 360-480 acryloyl chloride is added dropwise, heated to 30-40 DEG C, stirred for 12-18 h, filtered, the filtrate is rotary evaporated, petroleum ether washed, the product is dissolved in ethanol, heated to volatilize, cooled to crystallize, to obtain acrylate phthalimide polyethylene glycol. The reaction formula is:

[0015]

[0016] Further, the solvent in (2) is dichloromethane, chloroform or toluene.

[0017] Further, the environmentally friendly UV curing coating is applied to the thin film aluminizing process.

[0018] The present application has the beneficial technical effects: the present application uses polyethylene glycol diglycidyl ether, N-(4-carboxylphenyl) phthalimide, and acryloyl chloride as raw materials to prepare acrylate phthalimide polyethylene glycol containing two alkenyl groups, which is used as an active diluent to carry out a light curing reaction with epoxy acrylate. The acrylate phthalimide polyethylene glycol contains a flexible polyether molecular chain, which is crosslinked and cured into an epoxy resin, thereby achieving a good toughening effect and significantly improving the flexibility, impact resistance and bending strength of the coating.

[0019] The acrylic phthalimide polyethylene glycol contains a phthalimide structure with thermal stability, high structural stability and low thermal decomposition, so that the coating maintains good thermal decomposition temperature and heat resistance, the aluminum sheet is used as a base material, the coating has good adhesion and bonding performance, and has good practical application in the aluminum film plating process. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0021] The following epoxy acrylate, model EBECRYL 6040, is purchased from Shenzhen Longdi Chemical Co., Ltd.

[0022] Polyethylene glycol diglycidyl ether, molecular weight about 560, structural formula is Purchased from Shandong Lian Chemical Co., Ltd.

[0023] Polyethylene glycol diacrylate, molecular weight about 600, structural formula is Purchased from Guangdong Fangxin Biological Technology Co., Ltd.

[0024] N-(4-carboxyphenyl) phthalimide, CAS No. 5383-82-4, purchased from Anhui Zesheng Technology Anningji Chemical.

[0025] Example 1:

[0026] (1) 5g of polyethylene glycol diglycidyl ether, 6g of N-(4-carboxyphenyl) phthalimide and 0.44g of catalyst benzyl triethyl ammonium chloride were added to 80mL of toluene, heated to 110℃, stirred for 6h, and condensed backflow during reaction. After rotary evaporation, petroleum ether was washed, the product was dissolved in ethanol, heated and volatilized, and cooled and crystallized to obtain phthalimide polyethylene glycol.

[0027] (2) 3g of phthalimide polyethylene glycol and 12.6g of triethylamine were added to 100mL of toluene in an ice bath, 12.2g of acryloyl chloride was added dropwise, heated to 35℃, stirred for 18h, filtered, and the filtrate was rotary evaporated, petroleum ether was washed, the product was dissolved in ethanol, heated and volatilized, and cooled and crystallized to obtain acrylate phthalimide polyethylene glycol.

[0028] (3) To 26 g of tripropyleneglycol diacrylate, 70 g of epoxy acrylate, 5 g of acrylic phthalimidopolyglycol, 0.7 g of defoamer DOWSIL 102F, 0.2 g of leveling agent TEGO 2200N were added, after stirring, 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) was added to obtain an environmentally friendly UV-curable coating; finally, the coating was sprayed on the surface of the aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1.5 kW for 60 s to obtain an environmentally friendly UV-cured coating.

[0029] Comparative Example 1, the main difference between this comparative example and Example 1 is that tripropyleneglycol diacrylate is used instead of acrylic phthalimidopolyglycol.

[0030] (1) To 31 g of tripropyleneglycol diacrylate, 70 g of epoxy acrylate, 0.7 g of defoamer DOWSIL 102F, 0.2 g of leveling agent TEGO 2200N were added, after stirring, 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) was added to obtain an environmentally friendly UV-curable coating; finally, the coating was sprayed on the surface of the aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1.5 kW for 60 s to obtain an environmentally friendly UV-cured coating.

[0031] Comparative Example 2, the difference between this comparative example and Example 1 is that phthalimidopolyglycol is used instead of acrylic phthalimidopolyglycol.

[0032] (1) To 26 g of tripropyleneglycol diacrylate, 70 g of epoxy acrylate, 5 g of phthalimidopolyglycol, 0.7 g of defoamer DOWSIL 102F, 0.2 g of leveling agent TEGO 2200N were added, after stirring, 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) was added to obtain an environmentally friendly UV-curable coating; finally, the coating was sprayed on the surface of the aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1.5 kW for 60 s to obtain an environmentally friendly UV-cured coating.

[0033] Comparative Example 3, the main difference between this comparative example and Example 1 is that polyglycol diacrylate is used instead of acrylic phthalimidopolyglycol.

[0034] (1) To 26 g of tripropyleneglycol diacrylate, add 70 g of epoxy acrylate, 5 g of polyethylene glycol diacrylate, 0.7 g of defoaming agent DOWSIL 102F, 0.2 g of leveling agent TEGO 2200N, after stirring, add 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), to obtain an environmentally friendly UV-curable coating; finally, the coating is sprayed on the surface of an aluminum sheet substrate, and light curing is carried out in a UV curing machine with a power of 1.5 kW for 60 s to obtain an environmentally friendly UV-cured coating.

[0035] The main difference between Comparative Example 4 and Comparative Example 1 and Example 1 is that N,N'-bis(acrylate ethyl)-symphthaloylimide is used instead of acrylate phthaloylimide polyethylene glycol.

[0036] (1) N,N'-bis(hydroxyethyl)-symphthaloylimide is prepared according to the method of the journal “Chemistry and Adhesion”, 2021, 43(04), document “One-step preparation of N,N'-bis(hydroxyethyl)-symphthaloylimide”, the structural formula is

[0037] (2) In an ice bath, add 3 g of N,N'-bis(hydroxyethyl)-symphthaloylimide, 3.3 g of triethylamine to 40 mL of toluene, drop 3.7 g of acryloyl chloride, heat to 30°C, stir for 8 h, filter, the filtrate is rotary evaporated, then washed with petroleum ether, the product is dissolved in dichloromethane, and purified by recrystallization to obtain N,N'-bis(acrylate ethyl)-symphthaloylimide. The structural formula is

[0038]

[0039] (3) To 26 g of tripropyleneglycol diacrylate, add 70 g of epoxy acrylate, 5 g of N,N'-bis(acrylate ethyl)-symphthaloylimide, 0.7 g of defoaming agent DOWSIL 102F, 0.2 g of leveling agent TEGO 2200N, after stirring, add 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), to obtain an environmentally friendly UV-curable coating; finally, the coating is sprayed on the surface of an aluminum sheet substrate, and light curing is carried out in a UV curing machine with a power of 1.5 kW for 60 s to obtain an environmentally friendly UV-cured coating.

[0040] Example 2:

[0041] (1) To 80 mL of toluene, 5 g of polyethylene glycol diglycidyl ether, 6.6 g of N-(4-carboxyphenyl) phthalimide, 0.36 g of catalyst benzyl triethyl ammonium chloride were added, heated to 110°C, stirred for 8h, condensed reflux during reaction, washed with petroleum ether after rotary evaporation, the product was dissolved in ethanol, heated and evaporated, cooled and crystallized to obtain phthalimide polyethylene glycol.

[0042] (2) To 80 mL of dichloromethane, 3 g of phthalimide polyethylene glycol, 9.3 g of triethylamine were added in an ice bath, 10.8 g of acryloyl chloride was added dropwise, heated to 40°C, stirred for 18h, filtered, the filtrate was rotary evaporated, washed with petroleum ether, the product was dissolved in ethanol, heated and evaporated, cooled and crystallized to obtain acrylate phthalimide polyethylene glycol.

[0043] (3) To 24 g of 1,6-hexanediol diacrylate, 70 g of epoxy acrylate, 7 g of acrylate phthalimide polyethylene glycol, 0.5 g of defoaming agent DOWSIL 102F, 0.4 g of leveling agent TEGO 2200N were added, after stirring, 2.4 g of photoinitiator 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide (TPO) was added to obtain an environmentally friendly UV curing coating; finally the coating was sprayed on the surface of aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1 kW for 120 s to obtain an environmentally friendly UV curing coating.

[0044] Example 3:

[0045] (1) To 80 mL of toluene, 5 g of polyethylene glycol diglycidyl ether, 6.6 g of N-(4-carboxyphenyl) phthalimide, 0.36 g of catalyst benzyl triethyl ammonium chloride were added, heated to 110°C, stirred for 8h, condensed reflux during reaction, washed with petroleum ether after rotary evaporation, the product was dissolved in ethanol, heated and evaporated, cooled and crystallized to obtain phthalimide polyethylene glycol.

[0046] (2) To 100 mL of dichloromethane, 3 g of phthalimide polyethylene glycol, 11.3 g of triethylamine were added in an ice bath, 14.4 g of acryloyl chloride was added dropwise, heated to 30°C, stirred for 12h, filtered, the filtrate was rotary evaporated, washed with petroleum ether, the product was dissolved in ethanol, heated and evaporated, cooled and crystallized to obtain acrylate phthalimide polyethylene glycol.

[0047] (3) To 22 g of dipropylene glycol diacrylate, 70 g of epoxy acrylate, 10 g of acrylate phthalimidine polyglycol, 0.8 g of defoamer DOWSIL 102F, 0.4 g of leveling agent TEGO 2200N were added, and after stirring, 3 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) was added to obtain an environmentally friendly UV-curable coating. Finally, the coating was sprayed on the surface of an aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1.5 kW for 90 s to obtain an environmentally friendly UV-cured coating.

[0048] Example 4:

[0049] (1) To 20 g of tripropylene glycol diacrylate, 68 g of epoxy acrylate, 12 g of acrylate phthalimidine polyglycol (prepared in Example 1), 0.5 g of defoamer DOWSIL 102F, 0.3 g of leveling agent TEGO 2200N were added, and after stirring, 2.4 g of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) was added to obtain an environmentally friendly UV-curable coating. Finally, the coating was sprayed on the surface of an aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1 kW for 120 s to obtain an environmentally friendly UV-cured coating.

[0050] Example 5:

[0051] (1) To 18 g of tripropylene glycol diacrylate, 68 g of epoxy acrylate, 15 g of acrylate phthalimidine polyglycol (prepared in Example 1), 0.5 g of defoamer DOWSIL 102F, 0.3 g of leveling agent TEGO 2200N were added, and after stirring, 3.2 g of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) was added to obtain an environmentally friendly UV-curable coating. Finally, the coating was sprayed on the surface of an aluminum sheet substrate, and light curing was carried out in a UV curing machine with a power of 1 kW for 120 s to obtain an environmentally friendly UV-cured coating.

[0052] The flexibility of the coating was tested according to the method of GB / T 1731-2020 standard. The impact resistance was tested according to the method of GB / T 1732-2020 standard. The adhesion was tested according to the method of GB / T 9286-2021 standard.

[0053] The coating was poured into a mold, and light curing was carried out in a UV curing machine with a power of 1.5 kW for 240 s to make a cast body sample, and the bending strength was tested according to the method of GB / T 2567-2021.

[0054] 8 mg of the cured coating was weighed and placed in a thermal gravimetric analyzer for thermal gravimetric analysis in a nitrogen atmosphere at a heating rate of 10°C / min. The test results are shown in Table 1.

[0055] Table 1 Coating performance test

[0056]

[0057]

[0058] Compared with Comparative Example 1, Example 1 uses an acrylic ester phthalimide polyethylene glycol containing two alkenyl groups, a tripropylene glycol diacrylate as an active diluent, and an epoxy acrylate to perform a photocuring reaction, and the coating prepared thereby has better flexibility, impact resistance, and bending strength while maintaining good adhesion and initial (5% mass loss) thermal decomposition temperature and good heat resistance. This is mainly because the acrylic ester phthalimide polyethylene glycol contains a flexible polyether molecular chain, and the crosslinking and curing bond to the epoxy resin has a good toughening effect, significantly improving the flexibility, impact resistance, and bending strength of the coating. Moreover, the acrylic ester phthalimide polyethylene glycol contains a phthalimide structure with high structural stability and heat stability, and is not prone to thermal decomposition, avoiding the problem of poor heat resistance of the epoxy resin caused by the addition of polyethylene glycol, thereby making the coating exhibit good thermal decomposition temperature. Examples 2-5 add a small amount of acrylic ester phthalimide polyethylene glycol, and the epoxy coating still has good flexibility, impact resistance, bending strength, and thermal decomposition temperature.

[0059] Comparative Example 2 adds a phthalimide-based polyethylene glycol that does not contain an alkenyl group, which cannot undergo a photocuring reaction with the epoxy acrylate, resulting in poor curing effect of the epoxy acrylate and poor performance of the coating. Moreover, the polyether molecular chain is not chemically bonded to the epoxy acrylate, the toughening effect is poor, and the flexibility, impact resistance, and bending strength of the coating are poor.

[0060] Comparative Example 3 uses a conventional polyethylene glycol diacrylate as an active diluent to crosslink and cure the flexible polyether molecular chain into the epoxy resin, which has a good toughening effect, significantly improving the flexibility, impact resistance, and bending strength of the coating. However, the heat resistance and thermal decomposition temperature of the epoxy acrylate bonded with the polyether molecular chain are significantly reduced.

[0061] Comparative Example 4 uses N,N'-bis(acrylate ethyl)-sym-tetraformic acid diimide as an active diluent, which does not contain a flexible polyether molecular chain and does not have a toughening effect, and the flexibility, impact resistance, and bending strength of the coating are poor.

[0062] ​The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing an environmentally friendly UV-cured coating, characterized in that, The preparation method comprises: (1) reacting polyethylene glycol diglycidyl ether and N-(4-carboxyl phenyl) phthalimide to obtain phthalimide polyethylene glycol; and then reacting with acryloyl chloride to obtain acrylate phthalimide polyethylene glycol; (2) adding 68-70 parts by weight of epoxy acrylate, 5-15 parts by weight of acrylate phthalimide polyethylene glycol, 0.5-0.8 parts by weight of defoaming agent, and 0.2-0.4 parts by weight of leveling agent into 18-26 parts by weight of active diluent, stirring, then adding 2.4-3.2 parts by weight of photoinitiator to obtain an environmentally friendly UV curing coating; and finally spraying the coating on the surface of a substrate and performing light curing in a UV curing machine to obtain an environmentally friendly UV curing coating.

2. The method for preparing an environmentally friendly UV-cured coating according to claim 1, characterized in that, The active diluent is tripropylene glycol diacrylate, dipropylene glycol diacrylate, or 1,6-hexanediol diacrylate.

3. The method for preparing an environmentally friendly UV-cured coating according to claim 1, characterized in that, The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone or 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide.

4. The method for preparing an environmentally friendly UV-cured coating according to claim 1, characterized in that, The power of the UV curing machine is 1-1.5 kW, and the light curing time is 60-120 s.

5. The method for preparing the environment-friendly UV-cured coating according to claim 1, characterized in that, The preparation method of the acrylate phthalimide polyethylene glycol comprises: (1) adding 100 parts by weight of polyethylene glycol diglycidyl ether, 96-132 parts by weight of N-(4-carboxyl phenyl) phthalimide, and 7.2-8.8 parts by weight of benzyl triethyl ammonium chloride into toluene, stirring and reacting, then rotary evaporation, washing, dissolving the product in ethanol, heating and volatilizing, cooling and crystallizing to obtain phthalimide polyethylene glycol; (2) adding 100 parts by weight of phthalimide polyethylene glycol and 310-420 parts by weight of triethylamine into a solvent in an ice bath, and then adding 360-480 parts of acryloyl chloride dropwise, stirring and reacting, filtering, rotary evaporation of the filtrate, washing, dissolving the product in ethanol, heating and volatilizing, cooling and crystallizing to obtain acrylate phthalimide polyethylene glycol.

6. The method for preparing an environmentally friendly UV-cured coating according to claim 5, characterized in that, The temperature of the reaction in (1) is 100-110℃, and the reaction time is 6-9 h.

7. The method for preparing the environmentally friendly UV-curable coating according to claim 5, characterized in that, The temperature of the reaction in (2) is 30-40℃, and the reaction time is 12-18 h.

8. The method for preparing the environmentally friendly UV-curable coating according to claim 5, characterized in that, The solvent in (2) is dichloromethane, trichloromethane, or toluene.

9. An environmentally friendly UV curing coating obtained by the preparation method of any one of claims 1-8.

10. Use of the environmentally friendly UV curing coating of claim 9 in a thin film aluminizing process.

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