Environment-friendly high-performance low-temperature coating and preparation method thereof

Abstract

The application discloses an environment-friendly high-performance low-temperature paint and a preparation method thereof, and particularly relates to the technical field of low-temperature paint, which is composed of the following components in parts by weight: 30-45 parts of bio-based hyperbranched polyester acrylate resin, 15-25 parts of composite functional filler, 2-5 parts of low-temperature curing accelerator, 1-3 parts of water-based film-forming aid, 1-4 parts of environment-friendly aid and 20-35 parts of deionized water. The application solves the problem that the existing paint is difficult to balance between environmental protection and low-temperature film-forming performance from the core layer by taking bio-based hyperbranched polyester acrylate resin as a core film-forming component, and the paint has low-temperature curing and high performance, thereby breaking the limitation that a single filler is difficult to meet the multi-dimensional performance requirements of a coating film. Meanwhile, the pretreatment process effectively avoids the industry problem that nano-scale fillers are prone to agglomeration, further guarantees the stability of the performance of the paint, and effectively solves the problems of low curing efficiency, poor surface performance and easy deterioration during storage of the existing low-temperature paint.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low-temperature coating technology, and more particularly, relates to an environmentally-friendly high-performance low-temperature coating and a preparation method thereof. BACKGROUND

[0002] In the fields of industrial painting, building protection, outdoor facility maintenance, etc., low-temperature coatings become the focus of development in the coating industry due to their advantages such as adaptability to cold regions, reduced curing energy consumption, and protection of heat-sensitive substrates. However, the existing low-temperature coating technology still has many technical bottlenecks to be solved in terms of environmental friendliness, film-forming performance, comprehensive protection effect, and storage stability, etc.

[0003] Traditional low-temperature coatings mostly rely on petroleum-based resins, which not only consume fossil resources but also easily produce volatile organic compounds (VOCs), not meeting environmental protection requirements. Although some bio-based resins improve environmental friendliness, they have problems such as poor water dispersibility, insufficient component compatibility, and low film-forming density due to their linear or low-branched structure. It is difficult for them to form high-performance coatings at low temperatures, and the film-forming resins are difficult to balance environmental protection and low-temperature film-forming performance. The existing technology mostly uses single fillers to improve the performance of the coating, such as only using graphene or nano-silicon dioxide. However, single fillers cannot meet the requirements of mechanical strength and corrosion resistance at the same time, and nano-scale fillers are prone to agglomeration due to high surface energy, which is difficult to solve by existing dispersion processes, leading to uneven dispersion of fillers and reducing the density and corrosion resistance of the coating. In addition, single curing accelerators can reduce the curing temperature, but they are prone to insufficient curing, sticky coating surface, and poor adhesion. For high-activity systems designed to achieve rapid curing, they are prone to pre-crosslinking during storage at room temperature, resulting in increased viscosity and caking of the coating. Some water-based low-temperature coatings also have the defects of poor weather resistance and easy pulverization due to unreasonable system design. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides an environmentally-friendly high-performance low-temperature coating and a preparation method thereof to solve the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: an environmentally-friendly high-performance low-temperature coating, consisting of the following components by weight: 30-45 parts of bio-based hyperbranched polyester acrylate resin, 15-25 parts of composite functional filler, 2-5 parts of low-temperature curing accelerator, 1-3 parts of water-based film-forming additive, 1-4 parts of environmentally-friendly additive, and 20-35 parts of deionized water.

[0006] The bio-based hyperbranched polyester acrylate resin is formed by condensation polymerization of monomers containing bio-based polyols to form hyperbranched polyester, and then grafting modification with acrylic monomers.

[0007] The low-temperature curing accelerator is a compound of an organic bismuth compound and a erucic acid amide derivative with a mass ratio of 1:1.5-1:2.5;

[0008] The low-temperature curing accelerator of the present application needs to realize synergistic effect through compounding of organic bismuth and erucic acid amide derivative: organic bismuth reduces the curing activation energy, and erucic acid amide derivative improves the surface state. Single component cannot simultaneously meet the low-temperature curing efficiency and coating film performance. The compounding ratio range is verified to be effective through Examples 1-4.

[0009] The composite functional filler is a compound of graphene and amino-modified nanosilica with a mass ratio of 1:3 to 1:5.

[0010] Preferably, the bio-based polyol comprises isosorbide and bio-based propylene glycol, and the acid value of the bio-based hyperbranched polyester acrylate resin is 60 mgKOH / g-75 mgKOH / g, and the viscosity is 3000 mPa·s-5000 mPa·s.

[0011] Preferably, the carbon oxygen ratio of the graphene is 25:1 to 40:1, and the sheet size is not greater than 50 nm, and the particle size of the amino-modified nanosilica is 20 nm to 40 nm.

[0012] Preferably, the environmental protection aid includes 0.3 parts-1 part of water-based wetting agent, 0.2 parts-1 part of leveling agent, and 0.5 parts-2 parts of antioxidant.

[0013] A method for preparing the above-mentioned environmentally friendly high-performance low-temperature coating is also provided, comprising the following steps:

[0014] S1: composite functional filler pretreatment, dispersing the graphene and amino-modified nanosilica in part of deionized water, adding silane coupling agent, and obtaining a uniform and stable composite filler suspension through ultrasonic treatment and mechanical stirring;

[0015] S2: resin premixing, heating the bio-based hyperbranched polyester acrylate resin to 40-50°C, adding the water-based film-forming aid, and stirring at medium speed until mixed uniformly to obtain a resin mixture;

[0016] S3: composite dispersion, slowly adding the composite filler suspension obtained in S1 to the resin mixture obtained in S2, heating to 50-60°C, and dispersing under high-speed shearing for 40-60 minutes;

[0017] S4: aid preparation, cooling the system to 30-40°C, adding the low-temperature curing accelerator and the environmental protection aid, and stirring at medium speed until uniform;

[0018] S5: post-processing, grinding the obtained mixture to a fineness of no more than 15 mu m, adjusting the pH value to 7.5 to 8.5, standing to defoam, to obtain the paint.

[0019] Preferably, the frequency of the ultrasonic treatment in S1 is 20 kHz-30 kHz, and the time is 20 minutes-30 minutes; the rotating speed of the mechanical stirring is 800 r / min-1000 r / min, and the time is 15 minutes.

[0020] Preferably, the rotating speed of the high-speed shearing in S3 is 1800 r / min-2200 r / min, and the temperature is controlled to be no more than 65 DEG C during the process.

[0021] Preferably, the silane coupling agent in S1 is gamma-aminopropyl triethoxysilane, and the addition amount is 0.5%-1.5% of the total mass of the composite functional filler.

[0022] Technical effects and advantages of the present application:

[0023] 1. By taking a bio-based hyperbranched polyester acrylate resin as a core film-forming component, the resin is prepared by grafting modification of bio-based polyol polycondensation and acrylic monomer, which has significant bio-based characteristics, can reduce the dependence on petroleum-based raw materials, greatly improves the environmental protection properties of the paint, relies on the unique advantages of hyperbranched structure, has good water dispersibility, component compatibility and film-forming compactness, compared with traditional petroleum-based resin or non-hyperbranched resin, the bio-based hyperbranched resin can lay a good film-forming foundation for the paint without high temperature, which solves the problem of balancing the environmental protection and low-temperature film-forming performance of the existing paint from the core level, and provides key support for low-temperature curing and high performance of the paint.

[0024] 2. By the composite functional filler, graphene and amino-modified nanosilica are compounded according to a specific proportion, and the pretreatment process of silane coupling agent modification combined with ultrasonic and mechanical stirring is used to realize the uniform and stable dispersion of the filler in the paint system. The composite filler is not simply mixed, but utilizes the synergistic effect of the two-dimensional sheet structure of graphene and the surface activity of the amino-modified nanosilica to simultaneously enhance the mechanical strength and corrosion resistance of the coating film, breaking through the limitation that a single filler cannot meet the multi-dimensional performance requirements of the coating film. At the same time, the pretreatment process effectively avoids the industry problem of easy agglomeration of nanoscale fillers, further ensures the stability of the performance of the paint, and provides important protection for the comprehensive advantages of high hardness, impact resistance, corrosion resistance and other comprehensive advantages of the coating film.

[0025] 3. By compounding organic bismuth compounds with erucamide derivatives to construct a low-temperature curing accelerator, and combining it with environmentally friendly water-based additives to form a complete low-temperature curing system, it can not only significantly reduce the activation energy of the coating curing reaction, ensuring that the coating cures quickly and fully at lower temperatures, but also improve the surface condition of the coating film with the help of erucamide derivatives, enhancing adhesion and smoothness, and avoiding problems such as poor curing and surface stickiness that are easily caused by single curing accelerators. In addition, the coating adopts a water-based system as a whole, combined with the selection of environmentally friendly additives, so as to achieve low-temperature curing and high performance while ensuring the environmental friendliness of the production, construction and use processes. After post-processing adjustment, the coating also has good storage stability, effectively solving the problems of low curing efficiency, poor surface performance and easy deterioration during storage of existing low-temperature coatings. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides an environmentally friendly, high-performance low-temperature coating and its preparation method. The key components and processes involved in this invention will be described below.

[0028] Component definitions and descriptions:

[0029] Bio-based hyperbranched polyester acrylate resin: This resin is the film-forming material and key component of this invention. Its bio-based characteristics are derived from synthetic monomers, especially bio-based polyols such as isosorbide and bio-based propylene glycol. First, a hyperbranched polyester structure is formed through a polycondensation reaction. This structure contains a large number of terminal functional groups, which helps to reduce viscosity and provide more crosslinking points. Subsequently, through graft modification with acrylic monomers such as acrylic acid and methacrylic acid, acrylate groups that can be cured by ultraviolet light or low-temperature heat are introduced. The acid value of the resin is 60-75 mg KOH / g and the viscosity range is 3000-5000 mPa·s, which are key to ensuring its water dispersibility, film-forming properties and compatibility with other components.

[0030] Composite functional filler: It is a blend of graphene and amino-modified nano-silica of specific specifications. The high carbon-to-oxygen ratio of graphene (25:1 to 40:1) ensures its good electrical conductivity, thermal conductivity and mechanical strength. The small-sized sheets (≤50nm) are conducive to dispersion, while the amino-modified nano-silica (20-40nm) provides good surface activity and compatibility with resin. The blend of the two can produce a synergistic effect. The two-dimensional sheet structure of graphene and the spherical particles of nano-silica form an effective physical barrier, which together enhances the density, hardness, wear resistance and corrosion resistance of the coating.

[0031] Low-temperature curing accelerator: compounded by organic bismuth compound and erucamide derivative, organic bismuth as an environmentally friendly metal catalyst can significantly reduce the reaction activation energy of active groups in the resin, and erucamide derivative can migrate to the surface of the coating at low temperature, playing a role in lubrication and promoting leveling, and may have auxiliary catalytic effect on the curing process. The compounding of the two realizes the balance of catalytic efficiency and surface flatness.

[0032] Environmentally friendly additives: including water-based wetting agents to promote the spreading of coatings on substrates, leveling agents to eliminate defects such as brush marks and orange peel, and antioxidants to prevent oxidative degradation of resins during storage and curing.

[0033] Preparation method:

[0034] The essence of the preparation method is stepwise feeding, precise temperature control, and efficient dispersion.

[0035] S1 Composite functional filler pretreatment: first, use ultrasonic and mechanical stirring to fully depolymerize and pre-disperse the nanofiller in part of deionized water, and modify the surface of the nanofiller with silane coupling agent to improve the compatibility with the subsequent resin phase and prevent agglomeration.

[0036] S2 Resin premixing: slightly heat the resin and mix it with film-forming aids in advance to reduce the viscosity of the resin and prepare for subsequent reception of the filler suspension.

[0037] S3 Composite dispersion: under temperature control, high-speed shearing is performed to uniformly disperse the pretreated filler into the resin continuous phase to form a stable composite system.

[0038] S4 Additive adjustment: add temperature-sensitive curing accelerators and other additives at a lower temperature to avoid premature reaction or failure.

[0039] S5 Post-treatment: control product fineness by grinding to ensure coating appearance; adjust pH value to ensure system storage stability; and defoam by standing to achieve good construction effect.

[0040] The technical effects of the present application are further illustrated by a series of examples and comparative examples. Unless otherwise specified, the parts in the following examples are by weight.

[0041] The bio-based hyperbranched polyester acrylate resin in the following examples and comparative examples is prepared by the following method:

[0042] 1. Core raw material: the bio-based polyol is compounded by isosorbide and bio-based propylene glycol at a mass ratio of 1:1.2, and the acrylic monomer is compounded by acrylic acid and methacrylic acid at a mass ratio of 2:1.

[0043] 2. Synthesis process:

[0044] First step of polycondensation reaction: the bio-based polyol is put into a reactor, heated to 130°C, and 0.3% of tetrabutyl titanate based on the total mass of the bio-based polyol is added as a catalyst, and reacted for 3.5 hours to form a hyperbranched polyester intermediate.

[0045] Second step of graft modification reaction: the acrylic monomer is added to the above hyperbranched polyester intermediate, and 1% of azobisisobutyronitrile AIBN based on the total mass of the acrylic monomer is added as an initiator, and reacted at 80°C for 3 hours to obtain the target resin.

[0046] 3. Key performance parameters: the acid value of the obtained resin is 72 mgKOH / g, and the viscosity at 25°C is 4800 mPa·s, which is measured by a rotary viscometer. The above parameters together ensure excellent environmental friendliness, water dispersibility and low temperature film forming property of the resin.

[0047] The amino-modified nano-silica in the following examples and comparative examples is prepared by the following method:

[0048] 1. Modification process: γ-aminopropyl triethoxysilane KH-550 is used as a modifier, and the amount of KH-550 is 4% of the mass of the original nano-silica powder. During modification, the nano-silica is first dispersed in a mixed solvent of ethanol and water with a volume ratio of 3:1, then KH-550 is added, and stirred at 65°C for 3 hours. After the reaction is completed, the amino-modified nano-silica is obtained by centrifugation and drying.

[0049] 2. Key physical and chemical parameters: the particle size of the modified product is 30 nm, which is measured by dynamic light scattering method DLS, the surface amino content is 1.1 mmol / g, which is measured by acid-base titration method, and the specific surface area is 180 m² / g, which is measured by BET nitrogen adsorption method. The amino-modified nano-silica with the specific parameters can produce a synergistic effect with graphene, effectively improving the mechanical strength and corrosion resistance of the coating film, and can be uniformly dispersed through the pretreatment process of the present application, avoiding agglomeration.

[0050] Example 1:

[0051] Formulation: bio-based hyperbranched polyester acrylate resin 38 parts;

[0052] Composite functional filler: 20 parts;

[0053] Graphene (carbon-oxygen ratio 32:1, sheet size 30 nm): 4 parts;

[0054] Amino-modified nano-silica (particle size 30 nm): 16 parts;

[0055] Low temperature curing accelerator: 3.5 parts;

[0056] Organic bismuth (Borchikat0245): 1.4 parts;

[0057] Erdamide derivative (Smooth agent G-60): 2.1 parts;

[0058] Aqueous coalescent (dipropylene glycol butyl ether): 2 parts;

[0059] Environmental assistant: 1.5 parts;

[0060] Aqueous wetting agent (BYK-346): 0.5 parts;

[0061] Leveling agent (BYK-333): 0.4 parts;

[0062] Antioxidant (1010): 0.6 parts;

[0063] Deionized water: 30 parts;

[0064] Silane coupling agent 0.2 parts, KH-550, the addition amount is 1% of the total mass of the composite functional filler.

[0065] Preparation method:

[0066] Composite functional filler pretreatment: disperse 4 parts of graphene and 16 parts of amino-modified nanosilica in 10 parts of deionized water, add 0.2 parts of KH-550, ultrasonic treatment for 25 minutes at a frequency of 25 kHz, and mechanical stirring for 15 minutes at a speed of 900 r / min, to obtain a uniform and stable composite filler suspension.

[0067] Resin premixing: heat 38 parts of bio-based hyperbranched polyester acrylate resin in a 45℃ water bath, add 2 parts of aqueous coalescent, and stir at a speed of 500 r / min for 20 minutes to mix uniformly.

[0068] Composite dispersion: slowly add the suspension obtained in step 1 to the resin mixture of step 2. Raise the system to 55℃, and disperse at a high speed of 2000 r / min for 50 minutes, and control the temperature not to exceed 62℃ by water bath during the process.

[0069] Additive formulation: cool the system to 35℃, and sequentially add 1.4 parts of organic bismuth, 2.1 parts of erdamide derivative, 0.5 parts of wetting agent, 0.4 parts of leveling agent, and 0.6 parts of antioxidant, and stir at a speed of 600 r / min for 30 minutes to mix uniformly.

[0070] Post-treatment: grind the obtained mixture with a sand mill to a fineness of ≤15μm, adjust the pH value to 8.0 with ammonia water, and stand for defoaming for 24 hours to obtain the finished paint.

[0071] Example 2:

[0072] Compared with Example 1, the formulation dosage is shown in Table 1. In the preparation method, the high-speed shear dispersion time in step S3 is specified as 55 minutes, and the remaining process parameters and steps are exactly the same as in Example 1.

[0073] Example 3:

[0074] Compared with Example 1, the formulation dosage is shown in Table 1. In the preparation method, the high-speed shear dispersion time in step S3 is specified as 60 minutes, and the remaining process parameters and steps are exactly the same as in Example 1.

[0075] Example 4:

[0076] Compared with Example 1, the formulation dosage is shown in Table 1. In the preparation method, the ultrasonic treatment time in step S1 is specified as 30 minutes, and the mechanical stirring time is specified as 20 minutes.

[0077] The high-speed shear dispersion time in step S3 is specified as 55 minutes, and the remaining process parameters and steps are exactly the same as in Example 1.

[0078] The weight parts of the formulations for Examples 1-4 are shown in Table 1:

[0079]

[0080] Comparative Example 1:

[0081] Compared with Example 1, the composite functional filler was replaced with an equal amount of unrecombined amino-modified nano-silica, i.e., 20 parts, while the remaining components and preparation methods were exactly the same.

[0082] Comparative Example 2:

[0083] Compared with Example 1, the low-temperature curing accelerator was replaced with an equal amount of 3.5 parts of a single organic bismuth compound, without erucamide derivatives, while the remaining components and preparation methods were exactly the same.

[0084] Comparative Example 3:

[0085] Compared with Example 1, an equal amount of ordinary petroleum-based waterborne acrylic resin was used to replace the bio-based hyperbranched polyester acrylate resin of the present invention, while the remaining components and preparation methods were exactly the same.

[0086] The coatings obtained in Examples 1-4 and Comparative Examples 1-3 were sprayed or brushed onto sanded and cleaned tinplate or aluminum plates according to standard methods. They were then cured in an oven at 80°C for 20 minutes to simulate low-temperature curing conditions, and their performance was tested after 24 hours of curing.

[0087] The results are shown in Table 2:

[0088]

[0089] In summary, the embodiments 1-4 of the present application can be quickly cured at low temperature of 80℃ to form dense and hard coating film, and the mechanical properties, hardness, adhesion, impact resistance, flexibility and corrosion resistance are all very excellent;

[0090] The coating hardness and salt fog resistance of Comparative Example 1 significantly decrease due to the lack of graphene, which proves that the combination of graphene and nano-silica produces a synergistic reinforcing effect, and a single filler cannot achieve the same effect;

[0091] The coating of Comparative Example 2 has poor adhesion and sticky surface using a single curing accelerator, which proves that the combination of erucic acid amide derivative and organic bismuth can promote the overall curing, and improve the surface state and adhesion of the coating film;

[0092] Comparative Example 3 uses ordinary resin, which not only has overall inferior performance to the present application, but also requires higher curing temperature and time, which proves that the bio-based hyperbranched resin of the present application is the core to achieve low-temperature curing and high performance;

[0093] In summary, the present application successfully prepares an environmentally friendly high-performance low-temperature coating through the selection and dosage of specific components, especially the synergistic effect of bio-based resin, composite functional filler and combined accelerator.

[0094] Finally: The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An environmentally friendly high performance low temperature coating characterized in that: consists of 30-45 parts of a bio-based hyperbranched polyester acrylate resin, 15-25 parts of a composite functional filler, 2-5 parts of a low-temperature curing accelerator, 1-3 parts of a water-based film-forming aid, 1-4 parts of an environmentally friendly aid, and 20 to 35 parts of deionized water by weight; The bio-based hyperbranched polyester acrylate resin is formed by a condensation reaction of monomers containing bio-based polyols to form a hyperbranched polyester, and then grafted and modified with acrylic monomers; The low-temperature curing accelerator is a compound of an organic bismuth compound and a erucic acid amide derivative in a mass ratio of 1:1.5-1:2.

5. The composite functional filler is a compound of graphene and amino-modified nano-silica in a mass ratio of 1:3 to 1:

5.

2. The environment-friendly high-performance low-temperature coating according to claim 1, characterized in that: The bio-based polyol contains isosorbide and bio-based propylene glycol, and the acid value of the bio-based hyperbranched polyester acrylate resin is 60 mgKOH / g-75 mgKOH / g, and the viscosity is 3000 mPa·s-5000 mPa·s.

3. The environment-friendly high-performance low-temperature coating according to claim 1, characterized in that: The carbon oxygen ratio of the graphene is 25:1 to 40:1, and the sheet size is not greater than 50 nm, and the particle size of the amino-modified nano-silica is 20 nm to 40 nm.

4. The environment-friendly high-performance low-temperature coating according to claim 1, characterized in that: The environmentally friendly aid includes 0.3 parts-1 part of a water-based wetting agent, 0.2 parts-1 part of a leveling agent, and 0.5 parts-2 parts of an antioxidant by weight.

5. A method of preparing the environmentally friendly high performance low temperature coating as claimed in any one of claims 1 to 4, characterized in that: The steps include: S1: composite functional filler pretreatment, dispersing the graphene and amino-modified nano-silica in part of the deionized water, adding a silane coupling agent, and then ultrasonic treatment and mechanical stirring to obtain a uniform and stable composite filler suspension; S2: resin premixing, heating the bio-based hyperbranched polyester acrylate resin to 40℃ to 50℃, adding the water-based film-forming aid, and stirring at medium speed until mixed evenly to obtain a resin mixture; S3: composite dispersion, slowly adding the composite filler suspension obtained in S1 to the resin mixture obtained in S2, heating to 50℃ to 60℃, and dispersing under high-speed shearing for 40 minutes to 60 minutes; S4: aid preparation, cooling the system to 30℃ to 40℃, adding the low-temperature curing accelerator and the environmentally friendly aid, and stirring at medium speed until uniform; S5: post-treatment, grinding the obtained mixture to a fineness of not greater than 15μm, adjusting the pH value to 7.5 to 8.5, and standing to defoam to obtain the paint.

6. The method of claim 5, wherein: The frequency of ultrasonic treatment in S1 is 20kHz-30kHz, and the time is 20 minutes-30 minutes; the mechanical stirring speed is 800r / min-1000r / min, and the time is 15 minutes.

7. The method of claim 5, wherein: The high-speed shearing speed in S3 is 1800r / min-2200r / min, and the temperature is controlled not to exceed 65℃ during the process.

8. The method of claim 5, wherein: The silane coupling agent in S1 is γ-aminopropyl triethoxysilane, and the addition amount is 0.5%-1.5% of the total mass of the composite functional filler.

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