Self-repairing finish paint with high impact resistance

Abstract

The invention discloses self-repairing finishing paint with high impact resistance. The self-repairing finishing paint is prepared from acrylic modified polyester resin, elastic resin, partially etherified amino resin, pigment, filler, an organic solvent and auxiliaries. According to the self-repairing finishing paint, the impact resistance of a paint film is improved by adding the elastic resin, and meanwhile, the self-repairing finishing paint is promoted to have a self-repairing function under the reaction cross-linking action of the elastic resin, the acrylic modified polyester resin and the partially etherified amino resin, so that the reliability of a coating film is improved, and the service life of the coating film is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of coating preparation, and particularly relates to a highly impact-resistant self-repairing topcoat. Background Art

[0002] Self-healing coatings are intelligent materials with the ability to self-repair damage, similar to that of biological organisms. When damage such as cracks or scratches occurs, the coating can automatically or under external stimulation restore its original performance and integrity, effectively extending the coating's service life and reducing maintenance costs. Currently, the main technical approaches for self-healing coatings include microencapsulated self-healing, intrinsic self-healing, and externally assisted self-healing. Microencapsulated self-healing involves encapsulating a healing agent (such as a monomer or prepolymer) within microcapsules. When the coating is damaged, the capsules rupture, releasing the healing agent, which then repairs the damage through a curing reaction. However, their single-shot healing capability is limited, and their efficiency depends on the density of the capsules. Furthermore, the preparation process is complex, and large-scale production is costly. Intrinsic self-healing utilizes the reversible breaking and reforming of the material's own dynamic chemical bonds (such as Diels-Alder bonds, hydrogen bonds, and ionic bonds) to achieve repair. This allows for multiple repairs without the need for external healing agents. However, the introduction of dynamic bonds can reduce the coating's mechanical strength (such as hardness and impact resistance), and the design of these dynamic chemical bonds requires precise synthesis, making industrial application difficult. Externally assisted self-healing, which triggers a repair reaction through external stimuli (heat, light, humidity), is suitable for protective coatings on automobiles and electronic devices. However, this requires precise control of the stimulus conditions, limiting its environmental applicability. Furthermore, existing self-healing coatings struggle to balance repair performance with impact resistance, making them difficult to meet the demands of complex applications. Summary of the Invention

[0003] In view of the above-mentioned defects in the prior art, the present invention provides a highly impact-resistant self-repairing topcoat, the resulting paint film still has good self-repairing performance after being subjected to high-intensity impact.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A highly impact-resistant self-repairing topcoat, comprising the following raw material components in parts by weight: 28 parts of acrylic acid modified polyester resin; 12 parts of elastic resin; 8 parts of partially etherified amino resin; 29 parts of pigment; 8.1 parts of filler; 10 parts of organic solvent; 4.9 parts of auxiliary agent; The auxiliary agents include anti-settling agents, dispersants, leveling agents, drying agents, defoaming agents, cooling agents and polymerization inhibitors.

[0005] Furthermore, the pigment is titanium dioxide.

[0006] Furthermore, the filler is one or more of nano-silicon dioxide, fine talc powder, and ultrafine barium sulfate.

[0007] Furthermore, the organic solvent is one or more of butyl acetate, propylene glycol methyl ether acetate, and ethylene glycol butyl ether acetate.

[0008] Furthermore, the mass ratio of the anti-settling agent, dispersant, leveling agent, drying agent, defoaming agent, cooling agent and polymerization inhibitor in the auxiliary agent is 0.3:3:0.5:0.4:0.2:0.3:0.2.

[0009] Furthermore, the cooling agent is triethylamine, which can reduce the temperature required for resin cross-linking, improve the drying property of the paint film, reduce the baking temperature, and save energy consumption.

[0010] Furthermore, the polymerization inhibitor is methyl ethyl ketoxime, which can improve the storage properties of the paint.

[0011] Furthermore, the preparation method of the highly impact-resistant self-repairing topcoat comprises the following steps: (1) Premixing: Slowly add anti-settling agent, dispersant, defoamer, pigment and filler to the organic solvent in sequence, stir and mix at high speed, and then grind to a slurry fineness of ≤10μm; (2) Paint preparation: Add acrylic modified polyester resin, elastic resin, and partially etherified amino resin to the slurry obtained in step (1), and continue to add leveling agent, drying agent, cooling agent, and polymerization inhibitor under stirring conditions, stir and mix, and then filter to obtain the self-repairing topcoat.

[0012] Furthermore, the high-speed stirring in step (1) is performed at a speed of 800-1000 r / min and for a time of 20-30 min.

[0013] Furthermore, the stirring speed in step (2) is 600-800 r / min and the stirring time is 30-60 min.

[0014] The highly impact-resistant self-repairing topcoat prepared by the present invention can be used as a topcoat for metal products, fiberglass reinforced plastics and other products to achieve the effects of strong impact resistance and self-repair of micro-cracks. The specific coating operation is as follows: (1) Spraying: Spray the high impact resistant self-repairing topcoat onto the surface of the product, flash dry for 10-15 minutes, and then repeat the spraying operation, and control the film thickness obtained by each spraying to be between 25 μm and 30 μm; (2) Drying: Bake the sprayed product at 70-80℃ for 45-60min, then cool it to room temperature and leave it for 72 hours; the thickness of the resulting dry film is in the range of 80μm~120μm.

[0015] The beneficial effects of the present invention are: The highly impact-resistant self-repairing topcoat prepared by the present invention has excellent performance and meets the coating process requirements of automotive metal products: 1) Compared with ordinary PU topcoat, it has better impact resistance and less damage to the paint film at the same impact point after multiple impacts (impact times ≥ 3 times); 2) After the impact point is repaired, the paint film micro-texture can self-repair and no re-painting is required; 3) It does not contain harmful solvents such as benzene, VOC≤420, and is environmentally friendly; 4) It adopts blending modification instead of complex synthesis, which can be implemented based on existing equipment. Its preparation process is simple and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the infrared spectrum of the self-repairing topcoat prepared in the example. DETAILED DESCRIPTION

[0017] A highly impact-resistant self-repairing topcoat, the preparation of which comprises the following steps: (1) Slowly add 0.3 parts of anti-settling agent, 0.3 parts of dispersant, 0.2 parts of defoaming agent, 29 parts of pigment and 8.1 parts of filler to 10 parts of organic solvent in order by weight, stir at 800-1000 r / min for 20-30 minutes, and then grind to a slurry fineness of ≤10μm; (2) Paint preparation: add 28 parts of acrylic modified polyester resin, 12 parts of elastic resin, and 8 parts of partially etherified amino resin to the slurry obtained in step (1), and continue to add 0.5 parts of leveling agent, 0.4 parts of drying agent, 0.3 parts of cooling agent, and 0.2 parts of polymerization inhibitor under stirring conditions, stir and mix at 600-800 r / min for 30-60 minutes, and then filter to obtain the self-repairing topcoat.

[0018] Wherein, the pigment is titanium dioxide.

[0019] The filler is one or more of nano-scale silicon dioxide, fine talc powder (1250 mesh), and ultrafine barium sulfate (0.7 grade).

[0020] The organic solvent is one or more of butyl acetate, propylene glycol methyl ether acetate, and ethylene glycol butyl ether acetate.

[0021] The cooling agent is triethylamine.

[0022] The polymerization inhibitor is methyl ethyl ketone oxime.

[0023] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0024] In the following examples, the components of the composition are explained in parts by weight as a general standard. Unless otherwise specified, for the sake of simplicity, the "parts" in the examples of the present invention have the same meaning as parts by weight.

[0025] Specific raw material description: Acrylic modified polyester resin MR7361: purchased from Guangdong Keding Co., Ltd. Elastic resin modified polyol elastomer DC4011: purchased from Changxing Chemical; Partially etherified amino resin Luwipal® 012: purchased from BASF (China) Co., Ltd.; Pigment R706 titanium dioxide: purchased from The Chemours Company; Filler nano-silica HB-151: purchased from Fujian Yuanxiang New Materials Co., Ltd. 0.7 grade ultrafine barium sulfate: purchased from Henan Sanlian Micropowder Co., Ltd. 1250 mesh talc powder: purchased from Shanghai Junjiang Chemical Co., Ltd. Anti-settling agent R972: purchased from Degussa; Dispersant BYK-110: purchased from BYK Chemical Company, Germany; Leveling agent BYK-358N: purchased from BYK Chemical Company of Germany; Drier 10% T-12: purchased from Air Products and Chemicals, USA; Defoamer BYK-141: purchased from BYK Chemical Company, Germany; Cooling agent triethylamine: purchased from Shandong Weijin Chemical Technology Co., Ltd. Polymerization inhibitor methyl ethyl ketone oxime: purchased from Wuhan Hengjiu Chemical Co., Ltd. Example

[0026] Table 1 Formulation of self-repairing topcoat

[0027] The preparation of the self-healing topcoat includes the following steps: (1) Premixing: Add the organic solvent into the dispersion tank according to the formula in Table 1 and stir; then slowly add the anti-settling agent, dispersant, defoamer, pigment and filler in sequence, and stir at a high speed of 1000 r / min for 30 min; (2) Grinding: Grind the premixed slurry to a fineness of ≤10 μm using a sand mill; (3) Paint making: Add acrylic modified polyester resin, modified polyol elastomer, partially etherified amino resin, leveling agent, drying agent, cooling agent and polymerization inhibitor to the ground slurry, stir at 800 r / min for 30 min and filter to make the paint.

[0028] Comparative Example 1 No modified polyol elastomer was added, and the amounts of acrylic modified polyester and partially etherified amino resin were changed to 34 parts and 14 parts, respectively. Other operations were the same as those in the example.

[0029] Comparative Example 2 The amounts of acrylic modified polyester, modified polyol elastomer and partially etherified amino resin were changed to 30 parts, 8 parts and 10 parts respectively, and the other operations were the same as those in the example.

[0030] Comparative Example 3 The amounts of acrylic modified polyester, modified polyol elastomer and partially etherified amino resin were changed to 26 parts, 16 parts and 6 parts respectively, and the other operations were the same as those in the example.

[0031] Comparative Example 4 No cooling agent triethylamine was added, and other operations were the same as in the example.

[0032] Comparative Example 5 No polymerization inhibitor, methyl ethyl ketone oxime, was added, and other operations were the same as in the example.

[0033] Performance Testing The method and detection method of the obtained self-repairing topcoat for automobile painting are as follows: I. Prepare the matching curing agent according to the formula in Table 2. Then, mix the self-repairing topcoat and curing agent in a weight ratio of 4:1. Adjust the viscosity to 16-19S with a diluent. Spray the topcoat onto polished substrates such as automotive electrophoretic plates and aluminum sheets (spraying pressure 0.4 MPa, control the film thickness to 80-120 μm, and spray in two to three coats to avoid sagging). Allow the topcoat to level for 10-15 minutes. Ⅱ. Bake the sprayed metal plate at 70-80℃ for 40 minutes. After cooling, test the adhesion, flexibility, impact, self-repairing properties according to the methods in Table 3. After standing for 72 hours, test the water resistance, salt spray resistance, acid and alkali resistance, and gasoline resistance.

[0034] Table 2 Curing agent formula

[0035] Table 3 Performance testing methods

[0036] Table 4 Comparison of test results of various embodiments

[0037] From the results in Table 4, it can be seen that compared with the embodiment, when no elastomer is added (Comparative Example 1), the impact resistance of the paint film is significantly reduced, and the paint film has slight cracks after one impact, which does not meet the requirements.

[0038] When the amount of elastomer added was reduced (Comparative Example 2), the impact resistance of the paint film also decreased. The paint film had slight cracks after the second impact, which did not meet the requirements.

[0039] When the amount of elastomer added was increased (Comparative Example 3), the paint film had slight cracks after three impacts, and the self-repair rate of the flat surface was 85%, which met the requirements, but the hardness of the paint film decreased significantly, which did not meet the requirements.

[0040] Furthermore, uniform distribution of nanoparticles is crucial during the spraying process. The triethylamine added to the formula can adsorb onto the surface of nano-silica, altering its surface charge and reducing van der Waals-driven aggregation. This improves dispersion stability, enabling a more uniform distribution of resins and pigments, thereby enhancing the hardness and density of the paint film. A dense paint film structure transmits stress more evenly, inhibiting crack propagation and improving self-healing properties. Furthermore, when the paint film is impacted, it evenly distributes stress across the surface, preventing localized defects. Tests showed that when no triethylamine was added (Comparative Example 4), the paint film failed to meet the initial test hardness standard (pencil hardness of 2B) after baking at 70-80°C for 40 minutes, and even after standing for three days, the film's hardness remained low (pencil hardness of B). This is due to the film's insufficient density, which also affected its water and salt spray resistance, resulting in failures in both tests. Only by increasing the baking temperature (from 80°C to 120°C, as the ring-opening temperature of some etherified amino groups is typically 120°C) can the paint film reach its initial test hardness (pencil hardness H). Apparently, triethylamine can also act as a catalyst in a low-temperature baking environment to accelerate the reaction efficiency between various groups and between each group and isocyanate, lowering the glass transition temperature (Tg) of the paint film and allowing the paint film to crosslink rapidly in an environment no higher than 80°C, achieving a low-temperature baking and high hardness state.

[0041] In order to improve the impact resistance of self-repairing paint, this product introduces polyol elastomer resin and is prepared by a mixed modified multi-system resin method. Due to the presence of a large number of free groups in it, it is prone to adverse phenomena such as gelation and flocculation during long-term storage.

[0042] Table 5 Comparison of Stormer viscosity changes under constant temperature storage conditions

[0043] The data in Table 5 show that, compared to the examples, the product without the addition of the polymerization inhibitor methyl ethyl ketone oxime (Comparative Example 6) exhibited significant viscosity fluctuations and exhibited gelation and flocculation after 15 days of storage, making it unsuitable for long-term storage. This is because methyl ethyl ketone oxime forms a complex with the drier (T-12) through the oxime group (=C=NOH), temporarily inhibiting its activity and preventing premature oxidative polymerization and skinning during storage. During application, the rapid volatilization of methyl ethyl ketone oxime restores the drier's activity, promoting slow and uniform curing of the paint film and preventing localized over- or under-crosslinking during crosslinking. This uniform crosslinked network effectively disperses impact stress, improving the film's toughness and enhancing its high impact resistance.

[0044] As can be seen from the above, the present invention enhances the degree of cross-linking through acrylic modified polyester resin (rigidity), elastic resin (toughness), and partially etherified amino resin (cross-linking), so that the resulting paint film has self-healing properties and good impact resistance. The addition of triethylamine (cooling agent) and methyl ethyl ketone oxime (inhibitor) further improves the simplicity of coating preparation and its service life.

[0045] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. All variations or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention. All documents mentioned in this application are incorporated by reference in this application as if each document were individually incorporated by reference.

Claims

1. A highly impact-resistant self-repairing topcoat, characterized by: The topcoat comprises the following raw material components in parts by weight: 28 parts of acrylic acid modified polyester resin; 12 parts of elastic resin; 8 parts of partially etherified amino resin; 29 parts of pigment; 8.1 parts of filler; 10 parts of organic solvent; 4.9 parts of auxiliary agent; The auxiliary agents include anti-settling agents, dispersants, leveling agents, drying agents, defoaming agents, cooling agents and polymerization inhibitors.

2. The highly impact-resistant self-repairing topcoat according to claim 1, characterized in that: The pigment is titanium dioxide.

3. The highly impact-resistant self-repairing topcoat according to claim 1, characterized in that: The filler is one or more of nano-sized silicon dioxide, fine talc powder and ultrafine barium sulfate.

4. The highly impact-resistant self-repairing topcoat according to claim 1, characterized in that: The organic solvent is one or more of butyl acetate, propylene glycol methyl ether acetate, and ethylene glycol butyl ether acetate.

5. The highly impact-resistant self-repairing topcoat according to claim 1, characterized in that: The mass ratio of the anti-settling agent, dispersant, leveling agent, drying agent, defoaming agent, cooling agent and polymerization inhibitor in the auxiliary agent is 0.3:3:0.5:0.4:0.2:0.3:0.

2.

6. A highly impact-resistant self-repairing topcoat according to claim 1 or 5, characterized in that: The cooling agent is triethylamine.

7. A highly impact-resistant self-repairing topcoat according to claim 1 or 5, characterized in that: The polymerization inhibitor is methyl ethyl ketone oxime.

8. The highly impact-resistant self-repairing topcoat according to claim 1, characterized in that: The preparation method comprises the following steps: (1) Premixing: Slowly add anti-settling agent, dispersant, defoamer, pigment and filler to the organic solvent in sequence, stir and mix at high speed, and then grind to a slurry fineness of ≤10μm; (2) Paint preparation: Add acrylic modified polyester resin, elastic resin, and partially etherified amino resin to the slurry obtained in step (1), and continue to add leveling agent, drying agent, cooling agent, and polymerization inhibitor under stirring conditions, stir and mix, and then filter to obtain the self-repairing topcoat.

9. The highly impact-resistant self-repairing topcoat according to claim 8, characterized in that: The high-speed stirring in step (1) is performed at a speed of 800-1000 r / min and for 20-30 min.

10. The highly impact-resistant self-repairing topcoat according to claim 8, characterized in that: The stirring speed in step (2) is 600-800 r / min, and the stirring time is 30-60 min.

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