Coating composition and in-film injection molding hardened film containing coating composition

Abstract

The invention belongs to the technical field of in-film decoration, and relates to a coating composition and an in-film injection molding hardened film containing the coating composition. The coating composition comprises the following components: an aliphatic polyurethane acrylate oligomer with the functionality of 4-6, an acrylate monomer with the functionality of 1-4, a photoinitiator, a surface additive, a polyurethane acrylic resin prepolymer containing a polycarbonate structure, a curing agent and an organic solvent, the polyurethane acrylic resin prepolymer containing the polycarbonate structure is obtained by carrying out polymerization reaction on raw materials including polycarbonate polyol, diisocyanate, a chain extender and a catalyst. An aliphatic polyurethane acrylate oligomer with a special structure, an acrylic monomer and a polyurethane acrylic resin prepolymer containing a polycarbonate structure are introduced into the coating composition, so that the hardened film prepared from the coating composition has excellent hot stretch rate, and the hot stretch rate can reach more than 200%.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-mold decoration, and relates to a coating composition and an in-mold injection molding and hardening film comprising the coating composition. Background Art

[0002] Automotive in-mold decoration (IML) technology is an advanced surface decoration process. Its core process includes pre-preparing a thin film with a decorative pattern, then subjecting the thin film to high-pressure molding to form a predetermined shape, cutting the thin film and then placing it inside an injection molding die, and finally injecting molten polymer to fuse the thin film with the polymer, thereby directly forming a decorative pattern and button markings on the product surface. Compared with traditional spray painting technology, IML technology has significant advantages: it gives the product a stronger sense of solidity and improves the appearance texture of the product; it performs outstandingly in terms of environmental protection, reducing problems such as volatile organic compound (VOC) emissions during the spray painting process; moreover, the decorative patterns formed by IML technology have better durability, effectively avoiding problems such as fading and peeling, and greatly improving the quality and service life of the product. Currently, IML technology is widely used in the manufacture of exterior parts such as automotive center control air-conditioning control panels, instrument panels, and logos, and is one of the most cutting-edge technologies in the field of automotive interior decoration.

[0003] Automotive interiors are often contacted and rubbed by various objects during daily use, such as passengers' fingers, keys, clothing accessories, etc. To avoid scratching the product surface and maintain a good appearance, the thin film must have high surface hardness and excellent wear resistance. The automotive interior environment is complex, and the thin film needs to withstand the influence of natural factors such as temperature changes, ultraviolet radiation (sunlight enters the vehicle through the window), and humidity changes, and may also come into contact with various chemicals, such as cleaning agents, perfumes, beverages, etc. Therefore, good weather resistance can ensure that the thin film does not undergo phenomena such as discoloration, aging, and embrittlement during long-term use, maintaining the stability of its performance and appearance. Chemical resistance can prevent the thin film from being damaged by chemical substances, ensuring the integrity and safety of the interior. To achieve diverse designs of automotive interior products, especially the need for 3D modeling, the thin film must have good thermoforming properties. This enables the thin film to deform uniformly during heating, smoothly conform to the mold shape, and form complex three-dimensional structures, such as the curved surface of an automotive instrument panel and the three-dimensional contour of a center control panel. Good thermoforming properties can ensure that the product does not have defects such as cracking and wrinkling during the molding process, improving the molding quality and production efficiency of the product.

[0004] PC, PET, and PMMA films have good optical transparency and forming and stretching properties, and are very suitable for surface decoration. Their disadvantages are that the surface hardness is low and they are not wear-resistant, and they cannot meet the requirements of chemical resistance and weather resistance for automotive interiors. The in-mold injection hardening films commonly used in the fields of home appliances, 3C, etc. are transparent hard coatings coated on the surfaces of films such as PC, PET, and PMMA by thermal curing or ultraviolet curing to improve the hardness and surface wear resistance. However, currently, the hard coatings are difficult to soften during the heating process and have poor thermoforming properties. Compared with the relatively simple shapes of home appliances and 3C products, the in-mold injection hardening films for automotive interior products need to have higher thermo-stretching properties, so that they can be stretched to a greater extent without breaking during the thermoforming process to perfectly fit the mold shape and ensure the integrity and consistency of the decoration effect. If the thermo-stretching performance is insufficient, defects such as cracking and wrinkling may occur in the film during the forming process, resulting in product scrapping and affecting production efficiency and cost. Therefore, there is an urgent need to develop hardening films with higher performance such as thermo-stretching performance, wear resistance, weather resistance, and chemical resistance, and apply them to automotive interior parts to improve the quality and appearance of interior parts. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a coating composition and an in-mold injection hardening film containing the coating composition, and the in-mold injection hardening film has excellent thermo-stretching performance.

[0006] One aspect of the present invention provides a coating composition, comprising the following components:

[0007] Aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface assistant, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, organic solvent;

[0008] The functionality of the aliphatic polyurethane acrylate oligomer is 4 to 6;

[0009] The functionality of the acrylate monomer is 1 to 4;

[0010] The polyurethane acrylate resin prepolymer containing a polycarbonate structure is obtained by a polymerization reaction of raw materials including polycarbonate polyol, diisocyanate, chain extender, and catalyst.

[0011] Preferably, the chemical structural formula of the aliphatic polyurethane acrylate oligomer is:

[0012]

[0013] Among them, R 2 is one of an aliphatic chain segment with a carbon chain length of C4 to C8 and an alicyclic carbon ring of C4 to C8;

[0014] R 1 and R3 selected from linear, branched or cyclic C 4 ~C 8 alkyl;

[0015] n is selected from 4, 5 or 6.

[0016] More preferably, R 2 is one of an aliphatic chain segment with a carbon chain length of C5 to C8 and an alicyclic carbon ring of C5 to C8;

[0017] R 1 and R 3 are selected from linear, branched or cyclic C 5 ~C 8 alkyl.

[0018] Preferably, the weight-average molecular weight (Mw) of the aliphatic polyurethane acrylate oligomer is 1000 to 5000, and more preferably 2000 to 4000.

[0019] Examples of the aliphatic polyurethane acrylate oligomer include Allnex EBECRYL 8606, Allnex EBECRYL 8307, Allnex EBECRYL 8894, Allnex EBECRYL 8896, Changxing Chemical 6147, etc.

[0020] Preferably, the aliphatic polyurethane acrylate oligomer accounts for 40 to 75 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0021] Preferably, the acrylate monomer is one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate.

[0022] Examples of the preferred acrylate monomers include Changxing Chemical EM2260, EM2261, EM2265, EM223, EM224, EM226, and Korea Miwon M222, M2100, M280.

[0023] More preferably, the acrylate monomer is one or more of polyethylene glycol diacrylate and ethoxylated bisphenol A diacrylate.

[0024] More preferably, the weight-average molecular weight (Mw) of the polyethylene glycol diacrylate is 200 to 1000.

[0025] As further preferred acrylate monomers, examples include Changxing Chemical EM2260, EM2261, EM2265, EM224, EM226, and Korea Miwon M2100, M280.

[0026] Preferably, the acrylate monomer is 7-25 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer, and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0027] Preferably, the polyurethane acrylate resin prepolymer containing a polycarbonate structure is 28-45 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer, and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0028] The raw materials for preparing the polyurethane acrylate resin prepolymer containing a polycarbonate structure include: polycarbonate polyol, diisocyanate, chain extender, and catalyst.

[0029] Preferably, the polycarbonate polyol is a polycarbonate diol; considering the hot tensile properties of the finally prepared coating under high-temperature conditions for the target application, a polycarbonate polyol structure with a larger molecular weight needs to be matched. Therefore, the weight-average molecular weight of the polycarbonate polyol is preferably ≥800. Examples include commercially available DURANOL T5652, T5651 from Asahi Kasei, and PH100, PH200, PH300, etc. from Ube.

[0030] Considering the photoaging yellowing problem of the finally prepared coating, the diisocyanate is preferably an aliphatic diisocyanate, and examples include isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), etc.

[0031] Preferably, the chain extender is one or more of 1,4-butanediol, ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane. The prepolymer is chain-extended by the chain extender to increase the polymer molecular weight, which is beneficial to obtaining better hot tensile properties.

[0032] Preferably, the catalyst is an organometallic compound, and examples include zinc isooctanoate, zinc neodecanoate, dibutyltin dilaurate (DBTDL), stannous octoate T-9, potassium isooctanoate, bismuth isooctanoate, and bismuth neodecanoate.

[0033] In order to prevent the polymerization of C=C double bonds in the finally synthesized resin product, a polymerization inhibitor needs to be added during the polymerization process. The polymerization inhibitor is preferably 2,6-di-tert-butyl-p-cresol, p-methoxyphenol, triphenylphosphine, and hydroquinone. It is preferably better to use p-methoxyphenol as the polymerization inhibitor, and the color of the product is the lightest.

[0034] Preferably, the dosage of the polymerization inhibitor is 0.05-0.09% of the total amount of the polycarbonate polyol, diisocyanate, chain extender, catalyst and polymerization inhibitor, and more preferably 0.06%.

[0035] Preferably, the method for preparing the polyurethane acrylate resin prepolymer containing a polycarbonate structure comprises the following steps:

[0036] S1. Add the polycarbonate polyol, catalyst and solvent into a reaction kettle, keep the temperature at 50-70 °C for 10-40 min; then add the diisocyanate and react at 60-80 °C for 1-5 h to obtain prepolymer A;

[0037] S2. Dropwise add a solution containing a chain extender and a catalyst into prepolymer A, and keep the temperature at 60-80 °C for 1-5 h to obtain prepolymer B;

[0038] S3. Add a solution containing pentaerythritol triacrylate and a catalyst into prepolymer B, and react at 60-80 °C until the -NCO mass fraction ≤ 0.1% to obtain the polyurethane acrylate resin prepolymer containing a polycarbonate structure. When the raw materials include a polymerization inhibitor, further, step S3 is: add a solution containing pentaerythritol triacrylate and a catalyst into prepolymer B, then dropwise add the polymerization inhibitor, and react at 60-80 °C until the -NCO mass fraction ≤ 0.1% to obtain the polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0039] Preferably, in step S1, the -NCO / -OH molar ratio of the diisocyanate to the polycarbonate polyol is 1-1.5:1.

[0040] Preferably, in step S1, the mass of the catalyst is 0.05-0.08% of the total mass of the polycarbonate polyol, catalyst and diisocyanate.

[0041] Preferably, in step S2, the -NCO / -OH molar ratio of prepolymer A to the chain extender is 1.1-1.2:1.

[0042] Preferably, in step S2, the mass of the catalyst is 0.01-0.05% of the total mass of prepolymer A, catalyst and chain extender.

[0043] Preferably, in step S3, the molar ratio of pentaerythritol triacrylate to prepolymer B is 2-2.5:1.

[0044] Preferably, in step S3, the mass of the catalyst is 0.01-0.05% of the total mass of prepolymer B, catalyst and pentaerythritol triacrylate.

[0045] Preferably, in step S2, the solution containing the chain extender and the catalyst is formed by dissolving or dispersing the chain extender and the catalyst in a solvent, wherein the concentration range of the chain extender is 0.1-100 mg / ml. In step S3, the solution containing pentaerythritol triacrylate and the catalyst is formed by dissolving or dispersing pentaerythritol triacrylate and the catalyst in a solvent, wherein the concentration range of pentaerythritol triacrylate is 0.1-100 mg / ml.

[0046] The solvents for steps S1-S3 can include one or more of ethyl acetate, propyl acetate, and butyl acetate.

[0047] In the present invention, the polyurethane acrylate resin prepolymer containing a polycarbonate structure is obtained by neutralizing polycarbonate polyol with diisocyanate through stepwise addition polymerization, and the reaction mechanism is as follows:

[0048]

[0049] In the present invention, polycarbonate diol is selected to react with diisocyanate to generate urethane groups and a flexible chain segment structure composed of multiple polycarbonate chains. At the same time, by controlling the -NCO / -OH ratio, a high molecular weight prepolymer is obtained, so that the synthesized polymer has both good hardness and wear resistance, and good tensile properties under heating conditions. In addition, pentaerythritol is selected for grafting and capping. Pentaerythritol has a star structure, and its good molecular shielding effect can make the molecule very stable against small molecule chemicals, etc. At the same time, it has good photocuring speed and coating hardness, improving wear resistance and other properties.

[0050] Preferably, the photoinitiator is one or more of benzil and its derivatives, acylphosphine oxides, α-hydroxy ketones and their derivatives.

[0051] The photoinitiators can include one or more of 2-hydroxy-2-methyl-1-phenylpropanone (commercial model 1173), 1-hydroxycyclohexyl phenyl ketone (commercial model 184), 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphonate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0052] Preferably, the photoinitiator is 2-4.5 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer and the polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0053] Preferably, the surface assistant is an organosilicon leveling agent.

[0054] The surface additives may include one or more of commercially available BYK-333, BYK-330, BYK-UV3500, BYK-UV3505, BYK-UV3510, BYK-UV3535, Tego450, Tego410, and one or more of those in FL 3777.

[0055] Preferably, the surface additive is 0.01-0.06 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0056] Preferably, the curing agent is an isocyanate curing agent.

[0057] More preferably, the curing agent is an HDI, TDI, or MDI isocyanate curing agent.

[0058] Preferably, the curing agent is 0.2-0.5 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0059] Preferably, the organic solvent is one or more of dimethyl carbonate, ethyl acetate, isopropyl alcohol, and butanediol.

[0060] More preferably, the organic solvent is a mixture formed by dimethyl carbonate, ethyl acetate, and isopropyl alcohol in a mass ratio of (2-7):3:(2-5), or a mixture formed by dimethyl carbonate, ethyl acetate, and butanediol in a mass ratio of (2-7):3:(2-5). By setting the solvent components and ratio, the corrosiveness of the coating to the substrate surface is reduced.

[0061] Preferably, the organic solvent is 1.5-5 times the total mass of the aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylate resin prepolymer containing a polycarbonate structure.

[0062] Preferably, the viscosity of the coating composition at 23°C is 40-100 cps.

[0063] Another aspect of the present invention provides a method for preparing a coating composition, comprising the following steps:

[0064] Mix the aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface additive, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, and organic solvent, and stir evenly to obtain the coating composition.

[0065] A third aspect of the present invention provides an in-mold injection hardened film, comprising a substrate and a hardened film provided on the surface of the substrate, wherein the hardened film is prepared from the above coating composition.

[0066] Preferably, the substrate is one of PC, PMMA, or a composite substrate of PC and PMMA.

[0067] Preferably, the hardened film is obtained by coating the coating composition on a substrate, followed by drying and curing.

[0068] In order to achieve coating uniformity and appearance requirements, the lip gasket material of the coating die is an optical polyester film with a thickness fluctuation of no more than 0.2μm, a liquid cavity flow surface roughness of less than 5Ra, an inlet and manifold surface roughness of 6-10Ra, and a lip surface flatness of no more than 3μm. The glue supply system is controlled by a constant temperature at 23℃±1℃, and a pulse-free liquid supply pump is used to ensure a flow accuracy of ±0.5%, a repeatability accuracy of less than ±0.1%, and a pulsation rate of less than ±1%.

[0069] Furthermore, the vertical vibration fluctuation of the coating back stick is less than 2 μm, the water surface fluctuation is less than 1 μm, the height difference of the stick surface is less than 1 μm, and the coating head is closed and thermostatically controlled at 23°C ± 2°C.

[0070] Preferably, the coating thickness is 5 to 15 μm.

[0071] Preferably, the curing conditions include: light wavelength of 300-400nm, curing energy of 150-650mj / cm 2 , curing power ≥ 100 kW. The curing power is more preferably 100 to 800 kW.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] 1. The hardened film prepared by the coating composition provided by the present invention has excellent thermal stretching rate, and more preferably, the thermal stretching rate can reach more than 200%, and the hardened film has excellent transparency, chemical corrosion resistance (can meet various sunscreens and organic solvent tests in the automotive industry) and surface mechanical resistance.

[0074] 2. The present invention adopts coating technology to prepare in-mold injection molding hardening film, which significantly improves production efficiency compared with the traditional part spray painting process; the precise control of the composition and coating process makes the hardening film product have better surface quality, thereby greatly improving the appearance level of the surface of automotive interior parts.

[0075] 3. In the coating composition of the present invention, an aliphatic polyurethane acrylate oligomer with a special structure, an acrylic monomer, and a polyurethane acrylate resin prepolymer with a large molecular weight and a polycarbonate structure are introduced. The selection of these components is beneficial to improving the thermal stretching effect of the material at high temperatures. At the same time, the polyurethane acrylate resin prepolymer with a polycarbonate structure enables the coating to have better surface hardening and resistance (aging resistance and chemical resistance) at room temperature, and can meet the manufacturing requirements of various automotive 3D forming curved surfaces. Detailed Embodiments

[0076] The technical solutions of the present invention will be further described and illustrated through specific embodiments below. It should be understood that the specific embodiments described herein are only used to help understand the present invention and are not used for specific limitations of the present invention. If there is no special description, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0077] In the following examples and comparative examples, the polyurethane acrylate resin prepolymer with a polycarbonate structure is prepared by the following method:

[0078] S1. Accurately weigh the dehydrated polycarbonate diol (Duranol T5652), the catalyst DBTDL, and butyl acetate and add them to a reaction kettle equipped with a thermometer, a stirring paddle, and an air condenser. Heat up to 60 ± 2 °C and keep warm for 20 minutes. Then, use a constant pressure dropping funnel to dropwise add hexamethylene diisocyanate; after stirring, heat up to the set temperature of 70 ± 2 °C and keep the reaction constant for 2.5 hours to obtain a polyurethane prepolymer A capped with -NCO groups. Among them, the -NCO / -OH molar ratio of hexamethylene diisocyanate to polycarbonate diol is 1.3, and the mass of the catalyst is 0.07% of the total mass of polycarbonate diol, catalyst, and diisocyanate.

[0079] S2. Cool the polyurethane prepolymer A to 60 °C, and gradually dropwise add a solution containing 1,4-butanediol chain extender and catalyst DBTDL (formed by dissolving in butyl acetate, where the concentration range of the chain extender is 10 mg / ml), and then heat up to 70 °C and keep warm for 3 hours to obtain prepolymer B. Among them, the -NCO / -OH molar ratio of prepolymer A to 1,4-butanediol is 1.15, and the mass of the catalyst is 0.03% of the total mass of prepolymer A, catalyst, and chain extender.

[0080] S3. Cool prepolymer B to 60 ± 2 °C, slowly dropwise add a solution of pentaerythritol triacrylate and catalyst DBTDL (formed by dissolving in butyl acetate, where the concentration range of pentaerythritol triacrylate is 5 mg / ml), slowly dropwise add an inhibitor. After all the feeding is completed, keep the temperature constant at 70 ± 2 °C and react until the -NCO mass fraction ≤ 0.1%, and monitor in real-time by infrared at 2270 cm -1The -NCO characteristic peak disappears. A polyurethane acrylate resin prepolymer containing a polycarbonate structure with a large molecular weight is obtained. Among them, the molar ratio of pentaerythritol triacrylate to prepolymer B is 2.2:1. The mass of the catalyst is 0.03% of the total mass of prepolymer B, the catalyst, and pentaerythritol triacrylate.

[0081] Example 1

[0082] The coating composition of Example 1 is shown in Table 1:

[0083] Table 1

[0084]

[0085] Mix the aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface assistant, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, and organic solvent in Table 1, and stir evenly to obtain a coating composition. The viscosity of this coating composition at 23°C is 63 cps.

[0086] Example 2

[0087] The coating composition of Example 2 is shown in Table 2:

[0088] Table 2

[0089]

[0090]

[0091] Mix the aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface assistant, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, and organic solvent in Table 2, and stir evenly to obtain a coating composition. The viscosity of this coating composition at 23°C is 59 cps.

[0092] Example 3

[0093] The coating composition of Example 3 is shown in Table 3:

[0094] Table 3

[0095]

[0096] Mix the aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface assistant, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, and organic solvent in Table 3, and stir evenly to obtain a coating composition. The viscosity of this coating composition at 23°C is 50 cps.

[0097] Example 4

[0098] The coating composition of Example 4 is shown in Table 4:

[0099] Table 4

[0100]

[0101]

[0102] The aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface additive, polyurethane acrylate resin prepolymer containing a polycarbonate structure, curing agent, and organic solvent in Table 4 were mixed and stirred evenly to obtain a coating composition. The viscosity of this coating composition at 23 °C was 52 cps.

[0103] Example 5

[0104] The difference between Example 5 and Example 1 is only that the acrylate monomer in Example 5 is 10.5 parts of EM223 from Changxing Chemical Industry, and the others are the same as in Example 1.

[0105] Example 6

[0106] The difference between Example 6 and Example 3 is only that the acrylate monomer in Example 6 is 9 parts of Miwon M222 from Miwon, and the others are the same as in Example 3.

[0107] Comparative Example 1

[0108] The difference between Comparative Example 1 and Example 1 is that the aliphatic polyurethane acrylate oligomer in Comparative Example 1 is the 2-functional aliphatic polyurethane acrylate oligomer Changxing Chemical Industry 6118, and the others are the same as in Example 1.

[0109] Comparative Example 2

[0110] The difference between Comparative Example 2 and Example 1 is that the aliphatic polyurethane acrylate oligomer in Comparative Example 2 is the 10-functional aliphatic polyurethane acrylate oligomer Changxing Chemical Industry ETERCURE 61992, and the others are the same as in Example 1.

[0111] Comparative Example 3

[0112] The difference between Comparative Example 3 and Example 3 is that the acrylic monomer in Comparative Example 3 is the 5-functional dipentaerythritol pentaacrylate (DPPA), and the others are the same as in Example 3.

[0113] Comparative Example 4

[0114] The difference between Comparative Example 4 and Example 3 is that the acrylic monomer in Comparative Example 4 is Miwon M150 from Miwon, and the others are the same as in Example 3.

[0115] Comparative Example 5

[0116] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not include a polyurethane acrylic resin prepolymer containing a polycarbonate structure, and the rest is the same as Example 1.

[0117] Comparative Example 6

[0118] The difference between Comparative Example 6 and Example 1 is that Comparative Example 6 contains 30 parts of polyurethane prepolymer with polycarbonate structure, and the rest is the same as Example 1. The preparation method of polyurethane prepolymer with polycarbonate structure is as follows:

[0119] S1. Accurately weigh the dehydrated polycarbonate diol (Donaile T5652), catalyst DBTDL and butyl acetate, add them into a reactor equipped with a thermometer, a stirring paddle and an air condenser, heat it to 60±2°C and keep it warm for 20 minutes. Then add hexamethylene diisocyanate dropwise with a constant pressure dropping funnel; after stirring, heat it to a set temperature of 70±2°C, and react at a constant temperature for 2.5 hours to obtain a polyurethane prepolymer A (i.e., a polyurethane prepolymer with a polycarbonate structure) end-capped with an -NCO group. Among them, the -NCO / -OH molar ratio of hexamethylene diisocyanate to polycarbonate diol is 1.3, and the mass of the catalyst is 0.07% of the total mass of polycarbonate diol, catalyst and diisocyanate.

[0120] The coating compositions of Examples 1-6 and Comparative Examples 1-6 were coated on the surface of the PC substrate by slit coating, with a coating thickness of 10 μm; dried in an oven, and then cured: the wavelength of light was 365 nm, and the curing energy was 200 mj / cm 2 , the curing power is 200kw, and a hardened film is obtained.

[0121] During the coating process, the coating die lip gasket material is an optical polyester film, the thickness fluctuation is no more than 0.2μm, the liquid cavity flow surface roughness is less than 5Ra, the inlet and manifold surface roughness is 6-10Ra, and the lip surface flatness does not exceed 3μm; the glue supply system is controlled by constant temperature at 23℃±1℃, and a pulse-free liquid supply pump is used to ensure the flow accuracy of ±0.5%, the repeatability accuracy is less than ±0.1%, and the pulsation rate is less than ±1%. Furthermore, the vertical jump fluctuation of the coating back roll is less than 2μm, the water surface fluctuation is less than 1μm, the height difference of the roll surface is less than 1μm, and the coating head is closed and thermostatically controlled at 23℃±2℃.

[0122] The thermal elongation of the hardened films prepared from the coating compositions of Examples 1-6 and Comparative Examples 1-6 was measured (using a high temperature tensile machine, the stretching temperature was 150° C.), and the results are shown in Table 5; and the performance test was performed according to the Volkswagen TL226 automobile interior standard, and the results are shown in Table 5:

[0123] Table 5

[0124]

[0125] As can be seen from Table 1, the hardened films prepared from the coating compositions of Examples 1-4 have a relatively high thermal elongation rate, and this characteristic enables these hardened films to well meet the stretching requirements during the thermoforming process of automotive interior parts. In Example 5, a methacrylic monomer of Changxing Chemical EM223 was used compared with Example 1, and in Example 6, a methacrylic monomer of Miwon M222 was used compared with Example 3. Both Changxing Chemical EM223 and Miwon M222 are a kind of propylene glycol diacrylate. Compared with acrylate monomers such as polyethylene glycol diacrylate and ethoxylated bisphenol A diacrylate, the thermal elongation rate of the hardened films prepared using these two propylene glycol diacrylates is reduced.

[0126] In Comparative Example 1, a low-functional aliphatic polyurethane acrylate oligomer was used, and in Comparative Example 2, a high-functional aliphatic polyurethane acrylate oligomer was used. The thermal elongation rate of the hardened film prepared from this coating composition is greatly reduced compared with Example 1, and some of the other performance tests of Comparative Example 1 also failed. In Comparative Example 3, a methacrylic monomer with a functionality of 5 was used, and the methacrylic monomer used in Comparative Example 4 was Miwon M150. The inappropriate methacrylic monomer polymerized with the oligomer, and the obtained hardened film had poor thermal stretching performance. In Comparative Example 5, the polyurethane acrylate resin prepolymer containing a polycarbonate structure was not added, and the thermal elongation rate of the hardened film was only 5%, and some of the other performance tests did not pass; in Comparative Example 6, a polycarbonate structure-containing polyurethane prepolymer was added, and the thermal elongation rate was lower than that of the polyurethane acrylate resin prepolymer containing a polycarbonate structure in Example 1.

[0127] The above results show that the selection of the functionality of the aliphatic polyurethane acrylate oligomer, the selection of the methacrylic monomer, and the application of the polyurethane acrylate resin prepolymer containing a polycarbonate structure play a key role in the thermal elongation rate of the hardened film. Whether the functionality of the aliphatic polyurethane acrylate oligomer is too low or too high is not conducive to obtaining a hardened film with good thermal stretching performance. If the functionality and specific monomer type of the methacrylic monomer are not properly selected, it will directly lead to the thermal stretching performance of the hardened film not reaching the ideal level. The presence or absence of the polyurethane acrylate resin prepolymer containing a polycarbonate structure and whether it contains hydroxyl groups have obvious effects on the thermal elongation rate and other properties of the hardened film.

[0128] All aspects, embodiments, and features of the present invention should be considered illustrative in all respects and do not limit the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed invention, those skilled in the art will be aware of other embodiments, modifications, and uses.

[0129] In the preparation method of the present invention, the order of each step is not limited to the listed order. For those of ordinary skill in the art, without creative efforts, the changes in the sequence of each step are also within the protection scope of the present invention. In addition, two or more steps or actions can be carried out simultaneously.

[0130] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and do not limit the implementation manners of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. It is not necessary and impossible to list all the implementation manners here. And these obvious changes or variations derived from the essence of the present invention still fall within the protection scope of the present invention. Interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A coating composition, characterized in that The coating composition Includes the following components: Aliphatic polyurethane acrylate oligomer, acrylate monomer, photoinitiator, surface additive, polyurethane acrylic resin prepolymer containing polycarbonate structure, curing agent, organic solvent; Among them, the functionality of the aliphatic polyurethane acrylate oligomer is 4 to 6; The functionality of acrylate monomers is 1 to 4; The polyurethane acrylic resin prepolymer containing a polycarbonate structure is obtained by polymerization reaction of raw materials including polycarbonate polyol, diisocyanate, a chain extender and a catalyst.

2. A coating composition according to claim 1, characterized in that: The chemical structural formula of the aliphatic polyurethane acrylate oligomer is: wherein R2 is one of an aliphatic segment with a carbon chain length of C4 to C8, an alicyclic carbon ring with a carbon chain length of C4 to C8, R1 and R3 are selected from a linear, branched or cyclic C4 to C8 alkyl group, and n is selected from 4, 5 or 6; The weight average molecular weight of the aliphatic polyurethane acrylate oligomer is 1000 to 5000; The acrylic ester monomer is one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate.

3. A coating composition according to claim 1 or 2, characterized in that: The acrylic ester monomer is one or more of polyethylene glycol diacrylate and ethoxylated bisphenol A diacrylate; The weight average molecular weight of the polyethylene glycol diacrylate is 200-1000.

4. A coating composition according to claim 1, characterized in that: The method for preparing the polyurethane acrylic resin prepolymer containing a polycarbonate structure comprises the following steps: S1. Add polycarbonate polyol, catalyst and solvent into a reaction kettle, keep the temperature at 50-70°C for 10-40 minutes; then add diisocyanate at 60-80°C and react for 1-5 hours to obtain prepolymer A; S2, adding a solution containing a chain extender and a catalyst dropwise to prepolymer A, and reacting at 60-80° C. for 1-5 hours to obtain prepolymer B; S3, adding a solution containing pentaerythritol triacrylate and a catalyst to the prepolymer B, reacting at 60-80° C. until the mass fraction of -NCO is ≤0.1%, to obtain a polyurethane acrylic resin prepolymer containing a polycarbonate structure.

5. A coating composition according to claim 1 or 4, characterized in that: The polycarbonate polyol is a polycarbonate diol; The diisocyanate is an aliphatic diisocyanate; The chain extender is one or more of 1,4-butanediol, ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane; The catalyst is one or more of zinc isooctanoate, zinc neodecanoate, dibutyltin dilaurate, stannous octoate T-9, potassium isooctanoate, bismuth isooctanoate, and bismuth neodecanoate.

6. A coating composition according to claim 4, characterized in that: In step S1, the -NCO / -OH molar ratio of diisocyanate to polycarbonate polyol is 1 to 1.5:1; In step S1, the mass of the catalyst is 0.05-0.08% of the total mass of the polycarbonate polyol, the catalyst and the diisocyanate; In step S2, the -NCO / -OH molar ratio of prepolymer A to chain extender is 1.1 to 1.2:1; In step S2, the mass of the catalyst is 0.01-0.05% of the total mass of the prepolymer A, the catalyst, and the chain extender; In step S3, the molar ratio of pentaerythritol triacrylate to prepolymer B is 2 to 2.5:1; In step S3, the mass of the catalyst is 0.01-0.05% of the total mass of the prepolymer B, the catalyst and pentaerythritol triacrylate.

7. A coating composition according to claim 1, characterized in that: The photoinitiator is one or more of benzil and its derivatives, acylphosphine oxides, α-hydroxyketone and its derivatives; And / or, the surface additive is a silicone leveling agent; And / or, the curing agent is an isocyanate curing agent; And / or, the organic solvent is one or more of dimethyl carbonate, ethyl acetate, isopropanol, and butanediol.

8. A coating composition according to claim 1, characterized in that: The aliphatic polyurethane acrylate oligomer is 40-75wt% of the total mass of the aliphatic polyurethane acrylate oligomer, the acrylate monomer and the polyurethane acrylic resin prepolymer containing a polycarbonate structure; And / or, the acrylate monomer is 7 to 25 wt% of the total mass of the aliphatic polyurethane acrylate oligomer, the acrylate monomer and the polyurethane acrylic resin prepolymer containing a polycarbonate structure; And / or, the polyurethane acrylic resin prepolymer containing a polycarbonate structure is 28 to 45 wt% of the total mass of the aliphatic polyurethane acrylic ester oligomer, the acrylate monomer and the polyurethane acrylic resin prepolymer containing a polycarbonate structure; And / or, the photoinitiator is 2 to 4.5 wt% of the total mass of aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylic resin prepolymer containing polycarbonate structure; And / or, the surface additive is 0.01-0.06wt% of the total mass of aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylic resin prepolymer containing polycarbonate structure; And / or, the curing agent is 0.2-0.5wt% of the total mass of aliphatic polyurethane acrylate oligomer, acrylate monomer and polyurethane acrylic resin prepolymer containing polycarbonate structure; And / or, the organic solvent is 1.5 to 5 times the total mass of the aliphatic polyurethane acrylate oligomer, the acrylate monomer and the polyurethane acrylic resin prepolymer containing a polycarbonate structure.

9. An in-film injection molding hardening film, characterized in that: The invention comprises a substrate and a hardened film arranged on the surface of the substrate, wherein the hardened film is prepared from the coating composition according to any one of claims 1 to 8.

10. The in-film injection molding hardening film according to claim 9, characterized in that: The hardened film is obtained by coating the coating composition on a substrate, followed by drying and curing; Curing conditions include: light wavelength of 300-400nm, curing energy of 150-650mj / cm 2 , curing power ≥100kw.

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