EB curing coating composition as well as preparation method and application thereof

Abstract

The invention discloses an EB curing coating composition as well as a preparation method and application thereof, and the EB curing coating composition comprises the following components in parts by weight: 30-90 parts of a vinyl-terminated polyurethane prepolymer, 10-40 parts of a reactive diluent and 0.5-15 parts of an auxiliary agent, wherein the vinyl-terminated polyurethane prepolymer is prepared from a prepolymer A and a prepolymer B, and the vinyl-terminated polyurethane prepolymer is prepared from a vinyl-terminated polyurethane prepolymer A and a vinyl-terminated polyurethane prepolymer B; the EB curing coating composition disclosed by the invention can ensure that a cured coating has excellent scratch resistance and stripping strength, can be particularly applied to a multi-layer plastic film, and expands the development space of an EB curing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer composite materials, in particular to an EB curing coating composition, a preparation method and application thereof. BACKGROUND

[0002] Electron beam curing (EB curing for short) is an advanced material curing technology. Its core principle is to use high-energy electron beams to irradiate liquid chemicals. Through the interaction between electron beams and material molecules, it can induce molecular ionization or excitation, thereby generating free radicals or ions, and further inducing polymerization, crosslinking or grafting chemical reactions, so as to make the material rapidly solidify. This technology has gradually become a solidification process that attracts much attention in the field of material science due to its unique performance advantages.

[0003] EB curing technology has many significant advantages. First, its curing speed is extremely fast, and it can complete the curing process in a very short time, for example, in some cases, the curing time can be shortened to within 5 milliseconds, which makes EB curing have significant application advantages on high-efficiency production lines. Second, EB curing does not require the use of photoinitiators, which not only reduces material costs but also avoids potential performance problems caused by photoinitiator residues. In addition, the strong penetration of electron beams ensures the uniformity of the curing effect, whether it is the surface of the coating or the deep layer, consistent curing quality can be achieved. More importantly, EB curing is an environmentally friendly process, which produces almost no volatile organic compounds (VOCs) during the curing process, has minimal impact on the environment, and meets the requirements of modern industry for green manufacturing.

[0004] However, despite the many advantages of EB curing technology, it still faces some challenges in practical application. For example, the types of compositions that can be cured using this process are relatively few. This is mainly because EB curing has high requirements for the chemical structure and reaction performance of materials, and many existing material compositions are difficult to achieve ideal curing effects under EB curing conditions. In addition, material compatibility issues also limit the widespread application of EB curing technology. Due to factors such as molecular structure, functionality, molecular weight distribution, etc., the performance of the cured coating is often difficult to meet the requirements of industrial production. For example, the scratch resistance of the coating is poor, and scratches easily appear in mechanical friction; the peel strength of the coating and the substrate is low, which causes the coating to easily fall off, and these problems seriously affect the large-scale application of EB curing technology in the industrial field.

[0005] Therefore, developing a new composition that can adapt to the EB curing process is the key to solving the above problems. Such a composition not only needs to have good curing efficiency, but also should significantly improve the scratch resistance and peel strength of the cured coating to meet the actual needs of industrial production. SUMMARY

[0006] In view of the defects in the prior art, the present application provides an EB curing coating composition, a preparation method and application thereof.

[0007] The present application provides an EB curing coating composition, comprising the following components by weight parts: a vinyl-terminated polyurethane prepolymer 30-90 parts, such as 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 parts; a reactive diluent 10-40 parts, such as 10, 15, 20, 25, 30, 35, 40 parts; an auxiliary agent 0.5-15 parts, such as 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 15 parts; wherein the vinyl-terminated polyurethane prepolymer comprises a prepolymer A and a prepolymer B. The structure of the prepolymer A is as follows:

[0008] ; The structure of the prepolymer B is as follows: .

[0009] In the EB radiation curing process of the coating composition prepared in the present application, the double bonds of the acrylic ester groups in the four-arm polyethylene glycol acrylate can be activated and polymerized to form high molecular polymers.

[0010] Further, the mass ratio of the prepolymer A and the prepolymer B is (0.11-9):1, such as 0.11:1, 0.18:1, 0.23:1, 0.5:1, 0.8:1, 1:1, 1.5:1, 1.8:1, 2.3:1, 3:1, 4:1, 5:1, 6:1, 7:1, 7.5:1, 8:1, 9:1.

[0011] Further, the mass ratio of the prepolymer A and the prepolymer B is (1-9):1, more preferably (1-2.5):1.

[0012] Further, the reactive diluent is an acrylic ester monomer containing a double bond, and the acrylic ester monomer is selected from any one or more of a monofunctional acrylic ester monomer, a difunctional acrylic ester monomer or a multifunctional acrylic ester monomer.

[0013] The monofunctional acrylate monomer includes, but is not limited to, any one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, isobornyl acrylate, isobornyl methacrylate; the difunctional acrylate monomer includes, but is not limited to, any one or more of neopentyl glycol diacrylate, hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, neopentyl glycol dipropoxy diacrylate, neopentyl glycol dipropoxy dimethacrylate, 2-methyl-1,3-propanediol diacrylate; the multifunctional acrylate monomer includes, but is not limited to, any one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, propoxylated trimethylolpropane trimethacrylate, propoxylated glyceryl triacrylate, propoxylated glyceryl trimethacrylate, triallyl triisocyanate, trimethylallyl triisocyanate.

[0014] Further, the auxiliary agent is any one or more of a dispersant, a leveling agent, a defoaming agent, an antioxidant, an adhesion promoter, a thermal stabilizer, a filler, or a pigment.

[0015] Further, the auxiliary agent is any one or more of a dispersant, a leveling agent, a defoaming agent, an antioxidant, an adhesion promoter, a thermal stabilizer, a filler, or a pigment.

[0016] Further, the method for preparing the prepolymer A includes the following steps: S1: preparing N,N-dihydroxyethyl-3-aminopropionic acid methyl ester monomer 1; S2: In a four-mouth flask with a water trap, a feeding funnel and mechanical stirring, 1 mol of four-armed polyethylene glycol, 4.1-4.4 mol of N,N-dihydroxyethyl-3-aminopropyl methyl ester monomer 1 and 0.8-1.5 mol of p-toluenesulfonic acid are added, and then the mixture is heated to 130-150°C for 3.5-5 hours to obtain compound 2 in the form of a light yellow oil; S3: In a three-mouth round-bottom flask with dry polytetrahydrofuran as a solvent, 1 mol of compound 2 is added, and after installation of a stirring paddle and a thermometer, N2 is introduced for gas protection, and stirring is performed at 45-60°C for 25-32 min, then the temperature is raised to 70-84°C, 4.1-4.4 mol of isophorone diisocyanate (IPDI) is added to the flask, the temperature is continuously raised to 85-90°C, 0.05-0.1 mol of catalyst dibutyl tin dilaurate (DBTDL) is added, and reaction is performed under mechanical stirring for 1.5-2 h to obtain polyurethane intermediate 3; S4: After adjusting the temperature to 50-60°C, 4.1-4.4 mol of hydroxyethyl methacrylate (HEMA) is reacted for 3.5-5 h to obtain prepolymer A, and the reaction formula is as follows: ; The single-arm molecular weight of the four-armed polyethylene glycol is 2000-20000, such as 2000, 5000, 10000 or 20000.

[0017] The preparation method of the N,N-dihydroxyethyl-3-aminopropyl methyl ester monomer 1 includes the following steps: In a four-mouth flask with helium protection, a condenser and mechanical stirring, 1.0-1.5 mol of methyl acrylate and 1.01-1.51 mol of diethanolamine are added as solvents, stirring is performed at room temperature and under nitrogen protection for 28-35 min, then the temperature is raised to 38-45°C for reaction for 4-4.5 h, and methyl alcohol is removed by distillation to obtain colorless and transparent N,N-dihydroxyethyl-3-aminopropyl methyl ester monomer 1, and the reaction formula is as follows: .

[0018] Further, the preparation method of the prepolymer B includes the following steps: In a four-mouth flask with a water trap, a feeding funnel and mechanical stirring, 1 mol of four-armed polyethylene glycol isocyanate and 4.1-4.4 mol of hydroxyethyl methacrylate (HEMA) are added, and then reaction is performed at 58-65°C for 3.5-5 h to obtain prepolymer B, and the reaction formula is as follows: ; The single-arm molecular weight of the four-arm polyethylene glycol isocyanate is 2000-20000, such as 2000, 5000, 10000, 2000.

[0019] Further, the peel strength of the coating composition is ≥20 N.

[0020] The application also provides a preparation method of the coating composition, comprising the following steps: The coating composition is prepared by weighing the vinyl-terminated polyurethane prepolymer, active diluent and auxiliary agent according to the weight parts, uniformly mixing, and dispersing in a high-speed dispersion machine at 2800-3500 rpm for 70-85 minutes.

[0021] The application also provides an application of the coating composition in EB coating, especially in a multilayer plastic film, which can expand the development space of the EB curing process.

[0022] Further, the preparation method of the EB coating comprises the following steps: The surface of the substrate is pretreated, and then the coating composition is coated on the surface of the substrate, and the EB coating composite material is obtained by EB radiation curing in a protective gas atmosphere. The coating is, for example, spraying, rolling, micro-concave rolling, slot coating, showering, etc.

[0023] Further, the pretreatment includes but is not limited to removing impurities, cleaning or removing moisture, etc., and can also be surface roughening treatment or coating of a transition layer, etc.

[0024] Compared with the prior art, the application achieves the following technical effects: (1) The coating composition provided by the application can be applied to EB curing, which provides important industrial value for the development of the EB curing process. (2) The coating composition provided by the application has excellent scratch resistance and peel strength after EB curing, and can form a coating with good performance. DETAILED DESCRIPTION

[0025] In order to enable personnel in the art to better understand the application scheme, the technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the application.

[0026] EMBODIMENTS The application will be further described in connection with specific examples and comparative examples. The following specific examples are preferred embodiments of the application, but the embodiments of the application are not limited to the following examples, especially not to the types of the raw materials used in the following specific examples.

[0027] The sources of the raw materials used in the examples and comparative examples are as follows: The raw materials used in the examples and comparative examples of the application are commercially available, unless otherwise specified.

[0028] The preparation method of the prepolymer A#1 used in the examples of the application is as follows: S1: In a four-necked flask connected with a water trap, a feeding funnel and a mechanical stirrer, 1 mol of a four-armed polyethylene glycol (the molecular weight of a single arm is 2000), 4.1 mol of N,N-dihydroxyethyl-3-aminopropionic acid methyl ester monomer 1 and 1 mol of p-toluenesulfonic acid were added, and then the mixture was heated to 140°C for 4 hours to obtain a yellowish oil compound 2; S2: 1 mol of the compound 2 was added to a three-necked round-bottom flask with dry polytetrahydrofuran as a solvent, N2 was introduced for gas protection after the installation of a stirring paddle and a thermometer, and stirring was performed at 55°C for 30 min, then the temperature was raised to 80°C, 4.2 mol of isophorone diisocyanate (IPDI) was added to the flask, the temperature was continuously raised to 85°C, 0.08 mol of dibutyl tin dilaurate (DBTDL) was added as a catalyst, and the reaction was performed under mechanical stirring for 1.5 h to obtain a polyurethane intermediate 3; S3: After the temperature was adjusted to 50°C, 4.4 mol of hydroxyethyl methacrylate (HEMA) was reacted for 4 h to obtain a vinyl-terminated polyurethane prepolymer A#1; The preparation method of the N,N-dihydroxyethyl-3-aminopropionic acid methyl ester monomer 1 is as follows: In a four-necked flask connected with a helium gas protection, a condenser and a mechanical stirrer, 1 mol of methyl acrylate and 1.01 mol of diethanolamine were added as a solvent in 200 mL of methanol, stirring was performed at room temperature and under nitrogen protection for 30 min, then the temperature was raised to 40°C for reaction for 4 h, and methanol was removed by distillation to obtain colorless transparent N,N-dihydroxyethyl-3-aminopropionic acid methyl ester monomer 1.

[0029] The preparation method of the prepolymer A#2 used in the comparative examples of the application is as follows: S1: In a four-necked flask with a water separator, a charging funnel and mechanical stirring, 1 mol of PEG (single-arm molecular weight 2000), 2.1 mol of N, N-dihydroxyethyl-3-aminopropyl acid methyl ester monomer 1 and 0.2 mol of p-toluenesulfonic acid were added, the mixture was heated to 140℃ and reacted for 4 hours to obtain compound 5 in the form of light yellow oil; S2: In a three-necked round-bottom flask, 1 mol of compound 5 was added as a dry polytetrahydrofuran solvent, N2 was introduced for gas protection after the installation of a stirring paddle and a thermometer, and stirring was performed at 55℃ for 30 min, then the temperature was raised to 80℃, 2.2 mol of isophorone diisocyanate (IPDI) was added to the flask, the temperature was continuously raised to 85℃, 0.08 mol of dibutyl tin dilaurate (DBTDL) was added as a catalyst, and the reaction was performed under mechanical stirring for 1.5 h to obtain a polyurethane intermediate 6; S3: After adjusting the temperature to 50℃, 2.4 mol of hydroxyethyl methacrylate (HEMA) was reacted for 4 h to obtain a vinyl-terminated polyurethane prepolymer A#2, and the reaction formula was as follows: .

[0030] The preparation method of the prepolymer B used in the examples and comparative examples of the present application was as follows: In a four-necked flask with a water separator, a charging funnel and mechanical stirring, 1 mol of four-arm polyethylene glycol isocyanate (single-arm molecular weight 5000) and 4.1 mol of hydroxyethyl methacrylate (HEMA) were added, and then the reaction was performed at 60℃ for 4 h to obtain a vinyl-terminated polyurethane prepolymer B.

[0031] The preparation method of the coating composition of the examples and comparative examples of the present application was as follows: The vinyl-terminated polyurethane prepolymer, the active diluent and the auxiliary agent were added by weight parts, mixed, and dispersed in a high-speed disperser at 3000 rpm for 80 min to obtain the coating composition; wherein the active diluent was obtained by mixing hydroxypropyl acrylate, hexanediol diacrylate and trimethylolpropane triacrylate at a mass ratio of 1:1:1; and the auxiliary agent was obtained by mixing N, N'-ethylene bis-stearamide, BYK331 and BYK-1790 at a mass ratio of 1:2:2.

[0032] II. Performance test methods The surface of the polypropylene substrate was treated and placed at room temperature for more than 48 hours to ensure that the surface was dry and free of impurities. The polypropylene substrate was placed on an EB radiation curing device, the EB radiation curing coating composition was coated, and the EB radiation curing process was completed to obtain a composite film material.

[0033] (1) EB radiation curing conditions: under the conditions of radiation voltage 200 KeV, curing speed 400 m / min, electron beam dose 40 KGy, nitrogen concentration 200 mg / L, and curing temperature 25 °C.

[0034] (2) Scratch resistance: the test standard is ISO 1518-2:1992, a steel needle with a steel ball diameter of 1 mm is used, a motorized scratch tester is used to perform a one-way scratch test on the coating surface at a speed of 20 mm / s, the scratch length is 50 mm, the test is repeated 3-5 times, and the average value is taken. The load is increased when the steel needle is continuously scratched, and the load at which the coating is first scratched by the steel needle is recorded as an index for evaluating the scratch resistance of the coating. The greater the load, the better the scratch resistance.

[0035] (3) Interlayer peeling strength test: the peeling strength between the EB layer and the substrate of each composite film material is detected according to the A method in 4.1 of GB / T 8808-1988 "Soft composite plastic material peeling test method".

[0036] Table 1: Technical solutions and effects of examples (unit: parts by weight)

[0037] Table 2: Technical solutions and effects of comparative examples (unit: parts by weight)

[0038] In examples 1-10, prepolymers A and B mixed in a specific mass ratio, active diluents and auxiliaries are introduced at the same time, and all the coating compositions prepared in examples 1-10 can be cured by EB, and the cured coating has excellent scratch resistance and peeling strength, wherein the scratch resistance reaches 2000 and above, and the peeling strength is all ≥20 N.

[0039] Comparative examples 1-3 are compared with example 7, prepolymers A#2 used in comparative example 1 are not prepolymers with a specific structure according to the present application, which makes the coating brittle, has a certain hardness and scratch resistance, but the coating is easy to crack and fall off during the processing of the composite film material; only prepolymers B are used in comparative example 2, and the scratch resistance and peeling strength depend on the structure and crosslinking density of the crosslinked prepolymers B, and the small molecular weight of the prepolymers B makes the crosslinking speed too fast, which causes the deterioration of the uniformity and performance of the product; only prepolymers A are used in comparative example 3, which cannot guarantee the scratch resistance and peeling strength of the coating while being cured by EB.

[0040] Based on the test data of coating hardness, scratch resistance and peeling strength in Tables 1 and 2, the EB curing coating compositions prepared by examples 1-10 have obvious advantages compared with comparative examples, and can effectively meet the high standard requirements of customers and the market.

[0041] The above descriptions are only the preferred embodiment of the application, not intended to limit the application and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An EB curing coating composition, characterized in that Calculated by weight, it includes the following components: 30-90 parts vinyl terminated polyurethane prepolymer 10-40 parts of active diluent 0.5-15 parts of additives; Wherein, the vinyl terminated polyurethane prepolymer comprises prepolymer A and prepolymer B; The structure of the prepolymer A is as follows: ； The structure of the prepolymer B is as follows: 。 2. The composition according to claim 1, characterized in that The mass ratio of the prepolymer A to the prepolymer B is (0.11-9):

1.

3. The composition according to claim 2, characterized in that The mass ratio of the prepolymer A to the prepolymer B is (1-9):

1.

4. The composition according to claim 1, characterized in that The reactive diluent is an acrylate monomer containing a double bond, and the acrylate monomer is selected from any one or more of a monofunctional acrylate monomer, a difunctional acrylate monomer, or a multifunctional acrylate monomer.

5. The composition according to claim 1, characterized in that The auxiliary agent is any one or more of a dispersant, a leveling agent, a defoaming agent, an antioxidant, an adhesion promoter, a heat stabilizer, a filler or a pigment.

6. The composition according to claim 1, characterized in that The preparation method of the prepolymer B comprises the following steps: 1 mol of four-arm polyethylene glycol isocyanate and 4.1-4.4 mol of hydroxyethyl methacrylate were added to a four-necked flask, and then reacted at 58-65°C for 3.5-5 hours to obtain prepolymer B.

7. The composition according to claim 1, wherein The peel strength of the coating composition is ≥20 N.

8. The method for preparing the composition according to any one of claims 1 to 7, characterized in that: The steps include: The vinyl-terminated polyurethane prepolymer, reactive diluent and auxiliary agent are weighed in parts by weight, mixed evenly, and dispersed in a high-speed disperser at 2800-3500 rpm for 70-85 minutes to obtain the coating composition.

9. Use of the composition according to any one of claims 1 to 7 in EB coating.

10. The use according to claim 9, characterized in that The preparation method of the EB coating comprises the following steps: The surface of the substrate is pretreated, and then the composition is coated on the surface of the substrate, and EB radiation curing is adopted in a protective gas atmosphere to obtain a composite material with an EB coating.

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