Coating composition, coating agent, and coating layer

Abstract

The objective is to provide a coating composition, coating agent, and coating layer that can be applied to plastic surfaces, metal surfaces, ceramics, or painted surfaces such as those of automobiles, and that can improve gloss, self-cleaning properties, and stain resistance. [Solution] The coating agent of the present invention mainly consists of an alkoxysilane having a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, and contains a diluent solvent and an additive including a metal-based catalyst. When applied to plastic surfaces, metal surfaces, ceramics, or painted surfaces of automobiles, it suppresses the generation of bubbles, provides abrasion resistance, and allows the coating effect, including gloss, to be maintained for a long period of time.

Description

Technical Field

[0001] The present invention relates to a coating composition, a coating agent, and a coating layer. Specifically, it relates to a coating composition, a coating agent, and a coating layer that can be applied to the surface of plastics, metals, ceramics, or painted surfaces such as cars, and can improve glossiness, self-cleaning properties, and antifouling properties.

Background Art

[0002] For example, as a coating agent for the exterior of vehicles, glossiness, self-cleaning properties, and antifouling properties over a long period are required to maintain and improve the aesthetics of the exterior. Conventionally, as these methods, generally, protective agents such as wax and urethane clear coat resins have been used. Although these protective agents can provide effects such as glossiness and water repellency once applied, due to their thin film and low hardness, the abrasion resistance, weather resistance, chemical resistance, etc. of the coating film are insufficient, and it has been difficult to maintain the effects over a long period.

[0003] In addition, since the above-mentioned protective agents are weak in acid resistance and alkali resistance, etc., when removing various stains adhering to the exterior of the vehicle, it is necessary to use an acid-based or alkali-based cleaning agent, but these cleaning agents may damage the protective agent. Therefore, these protective agents need to be maintained regularly.

[0004] On the other hand, in recent years, instead of wax and urethane clear coat resins, glass-based coating agents and polysilazane-based coating agents have come to be used (Patent Document 1, Patent Document 2). These coating agents are excellent in chemical resistance such as acid resistance and alkali resistance, and are high-hardness materials, so they are also excellent in abrasion resistance, weather resistance, and antifouling properties, and are expected to compensate for the drawbacks of the above-mentioned protective agents, and are attracting attention as new protective agents to replace general wax and urethane clear coat resins.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-106972 [Patent Document 2] Japanese Patent Publication No. 2006-77071 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the aforementioned coating agents have the drawbacks of being difficult to apply uniformly, and if the coating becomes too thick or uneven, there is a risk of cracking or peeling. Furthermore, glass-based and polysilazane-based coating agents have very low viscosity, making them prone to air bubbles, streaks, and interference fringes (rainbow-like phenomena), and correcting them after application is also difficult.

[0007] Therefore, to solve these problems, it is common practice to apply the coating agent to the substrate surface and then wipe it off. By using a wipe-off method, the occurrence of air bubbles, streaks, and interference fringes is suppressed, and furthermore, the coating film can be applied in an ultrathin film, which can improve the occurrence of cracks, etc. On the other hand, because the thickness of the coating film is ultrathin, about 0.02 μm to 0.1 μm, it becomes difficult to maintain the coating effect over a long period of time.

[0008] In reality, most commercially available coating agents and those offered in the industry are designed for wipe-on application. As a result, the effects of these coatings typically last only about 6 months to 1 year, making it difficult to maintain the quality of the coating, including its gloss, over a long period. Therefore, regular maintenance is currently required.

[0009] The present invention was conceived in view of the above points, and relates to a coating composition, coating agent, and coating layer that can be applied to plastic surfaces, metal surfaces, ceramics, or painted surfaces of automobiles, and can improve gloss, self-cleaning properties, and stain resistance. [Means for solving the problem]

[0010] To achieve the above objective, the coating composition of the present invention mainly comprises an alkoxysilane having a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, or a silicon oligomer containing at least one such alkoxysilane.

[0011] Here, by using an alkoxysilane having 3 to 4 functional properties, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, or a silicon oligomer containing at least one alkoxysilane, as the main component of the coating composition, it is possible to suppress the generation of bubbles, obtain a certain level of hardness and wear resistance, and realize a coating agent that provides long-lasting coating effects, including gloss.

[0012] To achieve the above objective, the coating agent of the present invention comprises a main component containing an alkoxysilane having a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, or a silicon oligomer containing at least one such alkoxysilane, and a kinematic viscosity of 0.5 mm at 25°C. 2 / s~5mm 2 The solution comprises a diluent solvent consisting of a silicone oil with a flash point of 102°C or lower, and an additive containing a metal catalyst selected from an aluminum catalyst, a titanium catalyst, and a tin catalyst.

[0013] Here, by having a main component of the coating agent with a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, it is possible to suppress the generation of bubbles, obtain a certain level of hardness and wear resistance, and realize a coating agent that provides long-lasting coating effects, including gloss.

[0014] Furthermore, the diluent solvent has a kinematic viscosity of 0.5 mm at 25°C. 2 / s~5mm 2When it is silicone oil with a flash point of 102°C or lower, the generation of bubbles, streaks, or interference fringes can be suppressed.

[0015] In addition, when the metal-based catalyst is selected from an aluminum catalyst, a titanium catalyst, and a tin catalyst, the finish of the coating agent, the curability after a predetermined time, and the abrasion resistance become more stable.

[0016] In addition, when the main component is 5 wt% to 70 wt% and the diluent solvent is 28 wt% to 94 wt% with respect to the total amount of 100 wt% of the main component, diluent solvent, and additive, the finish of the coating agent becomes better.

[0017] In addition, when the coating layer obtained by applying and curing the coating agent on the substrate has an average thickness of 0.1 μm to 5.0 μm, a surface resistivity of 1×10 11 or less, and a contact angle of 90 degrees or more, it has excellent abrasion resistance, suppresses the generation of cracks, and can maintain the gloss for a long period of time.

[0018] By coating the above coating agent on the surface of the substrate by spray coating, dipping, or manual coating, a good finish with suppressed generation of bubbles, streaks, or interference fringes is obtained.

Advantages of the Invention

[0019] The coating composition, coating agent, and coating layer according to the present invention can be applied to the surface of plastics, metals, ceramics, or painted surfaces such as cars, and can improve gloss, self-cleaning properties, and antifouling properties.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the coating composition, coating agent, and coating layer according to the present invention will be described based on examples for the purpose of understanding the present invention. <​In order to sustain the long-term effect of a coating agent applied to a plastic surface, a metal surface, pottery, or a painted surface such as a car, it is necessary to use, as the main component, something with a bond energy greater than that of a siloxane bond (—Si—O—Si—), rather than the C—C bond of a general organic resin. Therefore, alkoxysilanes, silicon oligomers, resin oligomers, silane coupling agents, etc., which are components having such bonds, are considered as candidates. The characteristics of each composition are shown in Table 1.

[0022] [Table 1]

[0023] From the results in Table 1, since alkoxysilanes and silicon oligomers are superior to other components in terms of hardness and curability, attention was focused on alkoxysilanes and silicon oligomers as the main components (coating compositions) of the coating agent of the present invention.

[0024] Here, specific alkoxysilanes include dimethyldimethoxysilane (bifunctional), dimethoxydiphenylsilane (bifunctional), dimethyldiethoxysilane (bifunctional), methyltrimethoxysilane (trifunctional), N-propyltrimethoxysilane (trifunctional), N-propyltriethoxysilane (trifunctional), methyltriethoxysilane (trifunctional), hexyltrimethoxysilane (trifunctional), tetraethoxysilane (tetrafunctional), tetramethoxysilane (tetrafunctional), etc. Table 2 shows the components of the alkoxysilane samples (Alkoxysilane A to Alkoxysilane H) examined in the present invention.

[0025] [Table 2]

[0026] [Example 1] Coating agents were prepared using samples 1 to 8 shown in Table 2 as coating compositions. When the total proportion of the coating agent was 100 wt%, the ratio of alkoxysilane to diluent was fixed at 40 wt%:57 wt%, with the remainder consisting of various additives and catalysts. IPA was used as the diluent. The prepared coating agent was then applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. The formed coating layer was evaluated for bubble generation and abrasion resistance. The evaluation results are shown in Table 3.

[0027] In all the following examples, pencil hardness was measured in accordance with JIS K5600. Specifically, the sample was fixed on a horizontal table with the coated surface facing upwards, and the pencil was held at an angle of approximately 45 degrees. While pressing the pencil as hard as possible against the coated surface without breaking the lead, it was pushed forward at a uniform speed for about 1 cm to scratch the coated surface, and the hardness symbol of the hardest pencil that did not cause any tearing of the coated surface was indicated. Abrasion resistance was judged by the percentage decrease in gloss (percentage decrease in gloss (%) = (gloss before test - gloss after test) / gloss before test × 100) after passing steel wool (#0000) with a load of approximately 250 g back and forth 50 times.

[0028] [Table 3]

[0029] The results in Table 3 show that for alkoxysilanes, a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210 are desirable.

[0030] In this case, if the alkoxysilane has a functional number of 2, it will not have sufficient hardness to provide wear resistance, and long-term gloss retention cannot be expected. Also, if the flash point exceeds 60°C or the molecular weight exceeds 210, bubbles and other defects are likely to occur, making it difficult to obtain a satisfactory finish. On the other hand, if the flash point is below 5°C or the molecular weight is below 130, drying will be faster, the coatability will be poor, and streaks and interference patterns are likely to occur.

[0031] [Example 2] Next, as Example 2, we present the results of using a silicon oligomer as the coating composition. As silicon oligomers, we used silicon oligomer A (Sample 9) containing alkoxysilane A and alkoxysilane B, silicon oligomer B (Sample 10) containing alkoxysilane A and alkoxysilane C, silicon oligomer C (Sample 11) containing alkoxysilane A, alkoxysilane D, and alkoxysilane E, and silicon oligomer D (Sample 12) containing alkoxysilane E and alkoxysilane F, from among the alkoxysilanes shown in Table 2.

[0032] Then, coating agents were prepared using samples 9 to 12 as coating compositions. When the total proportion of the coating agent was 100 wt%, the ratio of silicon oligomer to diluent was fixed at 40 wt%:57 wt%, with the remainder consisting of various additives and catalysts. IPA was used as the diluent. The prepared coating agent was then applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. The formed coating layer was evaluated for bubble generation and abrasion resistance. The evaluation results are shown in Table 4.

[0033] [Table 4]

[0034] From Examples 1 and 2 described above, by selecting a silicon oligomer consisting of an alkoxysilane or a mixture thereof, having a functional number of 3 to 4, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, as the coating composition constituting the coating agent, it is possible to realize a coating agent that suppresses the generation of bubbles, provides a certain level of hardness and wear resistance, and maintains coating effects such as gloss for a long period of time.

[0035] [Example 3] In Example 3, the coating agent was prepared by adjusting the amount of the diluent solvent as a parameter, assuming the total coating agent content was 100 wt%. The total amount of coating composition α (alkoxysilane) and diluent solvent β was 97 wt%, with the remainder consisting of various additives and catalysts. The alkoxysilane used in Example 3 was sample 3 (alkoxysilane C), which showed good results in Example 1. The evaluation criteria included visual assessment of bubble generation, coating streaks, and cracks. The results are shown in Table 5.

[0036] [Table 5]

[0037] The results in Table 5 show that when coating composition α is 100 wt% (Sample 13), the wettability and applicability are poor, making it difficult to achieve a uniform coating, and therefore dilution with a specific solvent is necessary.

[0038] [Example 4] In Example 4, the effect of the diluent used on the finish of the coating layer was confirmed. For the preparation of the coating agent, samples 3 (alkoxysilane C) and 11 (silicone oligomer C), which showed good results in Examples 1 and 2, were used as coating composition α, and IPA, isoper G, methyl ethyl ketone, and silicone oil A were used as the diluent solvent β, respectively. The samples used in Example 4 are shown in Table 6. When the total proportion of the coating agent was set to 100 wt%, the ratio of coating composition α to diluent solvent β was fixed at 40 wt%:57 wt%, with the remainder being various additives.

[0039] [Table 6]

[0040] Then, each of the coating agents from samples 17 to 28 was applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. After drying and curing, the formed coating layers were visually inspected for the occurrence of bubbles, streaks, and interference fringes (rainbow phenomenon). The results are shown in Table 7.

[0041] [Table 7]

[0042] The results in Table 7 show that selecting silicone oil as the diluent β yields good results in all aspects affecting the finish, such as streaks, interference patterns, and bubble formation.

[0043] [Example 5] In Example 5, evaluation tests were conducted using the kinematic viscosity, flash point, and blending amount of the silicone oil that yielded good results as a diluent in Example 4 as parameters. The coating composition α used was alkoxysilane C. The samples used in Example 5 are shown in Table 8. The blending amounts in Table 8 are the respective amounts of coating composition α and diluent solvent β when the total coating agent is considered to be 100 wt%, with the remainder being various additives and catalysts.

[0044] [Table 8]

[0045] Then, each of the coating agents from samples 29 to 58 was applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. After drying and curing, the finish (bubble formation, streaks, interference fringes) and abrasion resistance of the formed coating layer were evaluated. The evaluation results are shown in Table 9.

[0046] [Table 9]

[0047] From the results in Table 9, the kinematic viscosity of the diluent β was 0.5 mm². 2 / s~5.0mm 2 It was found that using a silicone oil with a temperature of 25°C and a flash point of 102°C or lower, and with a coating composition α in the range of 5% to 70% and diluent solvent β in the range of 28% to 94%, yielded good results.

[0048] [Example 6] In Example 6, the effect on the coating layer was investigated when using a dilution solvent β, which was prepared by adding predetermined amounts of IPA, propylene glycol monomethyl ether, and isoper G to the main solvent, with silicone oil as the main solvent. Alkoxysilane C was used as the coating composition α. ​​Table 10 shows the components of the coating composition α and dilution solvent β used in the test of Example 6.

[0049] [Table 10]

[0050] Then, each of the coating agents from samples 59 to 70 was applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. After drying and curing, the formed coating layers were visually inspected for streaks, interference fringes (rainbow phenomenon), and the occurrence of air bubbles. The results are shown in Table 11.

[0051] [Table 11]

[0052] The results in Table 11 show that when silicone oil is used as the main solvent and the proportion of other solvents in the dilution solvent β is 20% or less, a good finish is achieved without the occurrence of streaks, interference fringes, or bubbles. However, as shown in samples 68 to 70, when isophar G was included as the other solvent, streaks and bubbles occurred. This is thought to be because isophar G is incompatible with silicone oil.

[0053] [Example 7] In Example 7, the type and amount of each catalyst added were used as parameters to confirm their effect on the coating layer. Alkoxysilane C was used for coating composition α, and silicone oil D was used for the diluent solvent β. Table 12 shows the components of coating composition α, diluent solvent β, and catalyst used in the test of Example 7.

[0054] [Table 12]

[0055] Then, each of the coating agents from samples 71 to 90 was applied to a glass plate using a bar coater to form a coating layer with a film thickness of approximately 3 μm. The formed coating layers were evaluated for finish and abrasion resistance. The evaluation results are shown in Table 13.

[0056] [Table 13]

[0057] The results in Table 13 show that using a metal catalyst, and specifically using a metal catalyst concentration of 0.5% to 5%, resulted in stable finish, next-day curing, and wear resistance. Phosphate catalysts, due to their high reactivity, caused unstable finishes such as whitening, and the final hardness achieved was lower compared to metal catalysts (aluminum, titanium, and tin), resulting in inferior wear resistance.

[0058] Furthermore, if the amount of metal catalyst is less than 0.5%, the initial curing ability may be insufficient, resulting in inadequate hardening of the coating film and potentially failing to achieve abrasion resistance. On the other hand, if the amount of metal catalyst exceeds 5%, whitening or cracking may occur.

[0059] Next, in Example 7, the electrostatic resistance and contact angle of the coating layer of sample 72, which showed good overall results, were measured. The contact angle was measured in accordance with JIS R 3257. Specifically, 3 μL of distilled water was dropped onto a sample prepared by coating a glass plate, and the radius of the surface of the water droplet in contact with the sample and the height from the sample surface to the top of the water droplet were measured to calculate the contact angle. Furthermore, the electrostatic properties (surface resistance) were measured five times each using a surface resistance measuring instrument (YC-103), and the average value was used (X represents an exponent that should be base 10. Therefore, the surface resistance is 10X Ω).

[0060] The measurement results are shown in Table 14. Antistatic agents include polyether-based and quaternary ammonium salts. Superhydrophobic agents include fluorine-based and silicone-based additives.

[0061] [Table 14]

[0062] The results in Table 14 show that by adding an antistatic agent and a superhydrophobic agent, the result is 1 × 10⁻⁶. 11 It can be seen that the coating exhibits properties of less than Ω and a contact angle of 90° or greater.

[0063] [Example 8] In Example 8, the effect of coating layer thickness was examined. Generally, if the film thickness is not appropriate, durability will be insufficient, and the risk of defects in the finish will increase. In Example 8, using sample 94 shown in Table 14, the thickness of the coating film was used as a parameter to evaluate the finish (bubble formation, streaks, interference fringes), abrasion resistance, and cracking. The evaluation results are shown in Table 15.

[0064] [Table 15]

[0065] As shown in Table 15, film thicknesses of less than 0.1 μm exhibit poor abrasion resistance, making it impossible to maintain gloss through general car washing or cleaning. On the other hand, when the coating film is thicker than 5 μm, cracks are more likely to occur. Therefore, to suppress crack formation and improve abrasion resistance, thereby maintaining the effectiveness of the coating agent over a long period, a coating layer thickness of 0.1 μm to 5.0 μm is preferable.

[0066] [Example 9] In Example 9, the effect of each application method on the coating layer was investigated, assuming the application of the coating agent to the substrate surface. Table 16 shows the coating agent and application method used in the test of Example 9. Note that the diluent β for samples 113 to 115 was a mixture of silicone oil D and IPA in a 9:1 ratio.

[0067] [Table 16]

[0068] Then, each of the coating agents from samples 110 to 115 was applied to a glass plate using its respective application method to form a coating layer. After drying and curing, the finished state (streaks, interference fringes, bubbles) and abrasion resistance of the formed coating layers were evaluated. The evaluation results are shown in Table 17.

[0069] [Table 17]

[0070] As shown in Table 17, for wipe-on application (samples 112 and 115), the film thickness was less than 0.1 μm, resulting in insufficient abrasion resistance and the inability to maintain the effect of the coating agent over a long period. On the other hand, spray application and sponge pad application (samples 110 and 111) For samples 113 and 114), the film thickness ranged from 0.1 μm to 5.0 μm, providing sufficient abrasion resistance and a good finish with suppressed occurrence of bubbles, streaks, or interference fringes.

[0071] As described above, the coating composition, coating agent, and coating layer according to the present invention can be applied to plastic surfaces, metal surfaces, ceramics, or painted surfaces such as those of automobiles, and can improve gloss, self-cleaning properties, and stain resistance.

Claims

1. The main component is an alkoxysilane having 3 to 4 functional properties, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, or a silicon oligomer containing at least one of the alkoxysilanes. Coating composition.

2. A main component comprising an alkoxysilane having 3 to 4 functional properties, a flash point of 5°C to 60°C, and a molecular weight of 130 to 210, or a silicon oligomer containing at least one such alkoxysilane, The kinematic viscosity at 25°C is 0.5 mm². ２ / s ~ 5mm ２ / s, a dilution solvent consisting of silicone oil with a flash point of 102°C or lower, The additive comprises a metal catalyst selected from an aluminum catalyst, a titanium catalyst, and a tin catalyst. Coating agent.

3. With respect to a total amount of 100 wt% of the main component, the diluent solvent, and the additive, The main component is 5 wt% to 70 wt%, and the diluting solvent is 28 wt% to 94 wt%. The coating agent according to claim 2.

4. The coating agent described in claim 2 or claim 3 is cured, Average thickness 0.1 μm to 5.0 μm, electrostatic resistance value 1 × 10⁻⁶ １１ The following applies when the contact angle is 90 degrees or more. Coating layer.

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