Protective varnish for airplane outer surface marking tape and preparation method of protective varnish

Abstract

The invention discloses protective varnish for an airplane outer surface marking tape and a preparation method of the protective varnish, and belongs to the technical field of functional protective varnish. The protective varnish comprises a base material and a curing agent, the base material comprises the following components in parts by weight: 60-70 parts of low molecular weight organosilicon modified epoxy resin, 1-10 parts of glass powder, 0.5-3 parts of a defoaming agent, 0.5-3 parts of a leveling agent and 10-30 parts of a mixed solvent, and the curing agent system comprises the following components in parts by weight: 1-5 parts of a catalyst and 1-5 parts of an amine curing agent. The protective varnish provided by the invention overcomes four core defects of conventional varnish, can play a role in protecting a marking tape on the outer surface of an airplane, and has the advantages of insolubility of printing content of the marking tape, high high temperature resistance, good edge sealing effect, high normal-temperature curing speed and the like.

Description

Technical Field

[0001] This application belongs to the field of functional protective varnish technology, specifically, it relates to a protective varnish for marking tapes on the outer surface of aircraft and its preparation method. Background Technology

[0002] Aircraft exterior markings are used for identification, safety warnings, etc. These markings are printed from resin-based carbon ribbons (containing resin, carbon black, or fade-resistant dyes). To prevent wear and fading, the industry typically protects the markings by applying a clear varnish to the outer surface. However, current mainstream clear varnishes (such as CO1-7 alkyd varnish) have significant drawbacks: first, they are incompatible with the printed content, and the solvent easily dissolves the printed layer, resulting in blurred text; second, they have poor edge sealing, failing to seal the marking edges and allowing rainwater to seep in and corrode the markings; third, they lack high-temperature resistance, causing the varnish film to yellow and crack at high temperatures, losing its protective function; and fourth, their slow curing speed at room temperature often leads to extended aircraft maintenance downtime, impacting operational efficiency. In summary, existing varnishes cannot meet the protection requirements of the aviation industry for marking tapes, and there is an urgent need to develop a new type of protective varnish that is compatible with the printed content, has strong edge sealing properties, is resistant to high temperatures, and can cure quickly. Summary of the Invention

[0003] The purpose of this application is to provide a protective varnish for aircraft outer surface marking tape and its preparation method. The protective varnish is well compatible with the printed content of the marking tape and has the advantages of excellent edge sealing effect, good high temperature resistance and rapid curing at room temperature, which can further improve the service life and maintenance efficiency of aircraft marking tape.

[0004] To achieve the above objectives, this application provides a protective clear coat for marking tape on the outer surface of an aircraft, comprising a base material and a curing agent system, wherein the base material comprises the following components in parts by weight: 60 to 70 parts of low molecular weight silicone-modified epoxy resin, 1 to 10 parts of glass powder, 0.5 to 3 parts of defoamer, 0.5 to 3 parts of leveling agent, and 10 to 30 parts of mixed solvent.

[0005] Furthermore, the molecular weight of the low molecular weight organosilicon modified epoxy resin is below 3000, and the organosilicon monomer of the low molecular weight organosilicon modified epoxy resin includes at least one of phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane.

[0006] Furthermore, the low molecular weight organosilicon-modified epoxy resin is prepared by the following method: The organosilicon monomer, water, and acetic acid are mixed and then subjected to a pre-hydrolysis reaction. The product is prepared by adding low molecular weight epoxy resin, heating and reacting, and then separating and purifying it.

[0007] Furthermore, the mass ratio of the organosilicon monomer, water, acetic acid, and low molecular weight epoxy resin is 5~15:5:2:100.

[0008] Furthermore, the reaction temperature of the pre-hydrolysis reaction is 45℃~55℃, and the reaction time is 100min~150min.

[0009] Furthermore, the reaction temperature of the heating reaction is 75℃~85℃, and the reaction time is 4.5h~5.5h.

[0010] Furthermore, the mixed solvent comprises propylene glycol methyl ether acetate, xylene, and n-butyl acetate in a mass ratio of 40~50:30~40:10~30.

[0011] Furthermore, the defoamer includes at least one of BYK-066N, BYK-077, and BYK-085.

[0012] Furthermore, the leveling agent includes at least one of BYK-306, BYK-310, and BYK-330.

[0013] Furthermore, the glass powder has a particle size of 600 mesh, 800 mesh, 1250 mesh, 3000 mesh, or 5000 mesh.

[0014] Furthermore, the curing agent system comprises the following components in parts by weight: 1 to 5 parts of catalyst and 1 to 5 parts of amine curing agent.

[0015] Furthermore, the catalyst is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex or a 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane platinum complex.

[0016] Furthermore, the amine curing agent includes at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, and hexamethylenediamine.

[0017] This application also provides a method for preparing a protective varnish for marking tapes on the outer surface of an aircraft, comprising the following steps: The low molecular weight organosilicon modified epoxy resin is mixed with a mixed solvent and then dispersed uniformly at a first rotation speed. The glass powder is added and dispersion is continued to obtain a premixed liquid. The defoamer and leveling agent are added to the premixed liquid and dispersed uniformly at the second rotation speed to obtain a dispersion. The dispersion was ball-milled at a third rotation speed and then sieved to obtain the base material; The catalyst and amine curing agent are mixed and dispersed evenly at the first rotation speed to obtain the curing agent; Before use, the base material and the curing agent are mixed to prepare the protective varnish for the aircraft outer surface marking tape.

[0018] Furthermore, the first rotational speed is 800 r / min to 1000 r / min, the second rotational speed is 500 r / min to 800 r / min, the third rotational speed is 300 r / min to 350 r / min, and the dispersion time for each dispersion is 10 min to 30 min.

[0019] In summary, this application has the following advantages: The protective varnish for aircraft outer surface marking tapes proposed in this application precisely addresses the four core defects of existing conventional varnishes. It boasts four outstanding advantages: excellent compatibility (does not dissolve the printed content of the marking tape), strong high-temperature resistance, excellent edge sealing effect, and rapid curing at room temperature. It fully meets the stringent requirements of the aviation industry for marking tape protection. Furthermore, the formulation's component dosages are precisely controllable, and the raw materials are readily available, balancing performance stability and economy. It is perfectly suited for aircraft outer surface marking tape protection scenarios, effectively extending marking tape life and improving aircraft maintenance efficiency.

[0020] Specifically, this application first uses low molecular weight silicone-modified epoxy resin as the core resin, combined with glass powder. The high-temperature stability of silicone and the dense adhesion of epoxy resin lay the foundation for high-temperature resistance (no yellowing or transparency at 150℃ for 100 hours). Second, a mixed solvent system is used to avoid single aromatic solvents. Combined with the precise dosage of defoamer and leveling agent, the problem of dissolving the printed content of the label tape is solved, and excellent edge sealing effect is achieved by balancing leveling and shrinkage. Furthermore, the platinum metal catalyst and highly active amine curing agent in the curing system work synergistically to significantly reduce the curing temperature and accelerate the reaction, achieving rapid curing at room temperature of 25℃ for 4 hours. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram showing the effect of the protective varnish after use according to Embodiment 1 of this application.

[0023] Figure 2 This is a schematic diagram illustrating the effect of the protective varnish proposed in Comparative Example 1 of this application after application.

[0024] Figure 3 This is a schematic diagram illustrating the effect of the protective varnish proposed in Comparative Example 2 of this application after application.

[0025] Figure 4 This is a schematic diagram illustrating the effect of the protective varnish proposed in Comparative Example 3 of this application after application. Detailed Implementation

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

[0027] The clarity, accuracy, and durability of markings on aircraft exteriors are crucial for flight safety, routine maintenance, brand recognition, and regulatory compliance. These markings are typically affixed to the aircraft exterior using adhesive tapes, with the content printed on the tapes usually using resin-based carbon ribbons. Resin-based carbon ribbons are widely used due to the excellent weather resistance, abrasion resistance, and adhesion of the printed markings. Their main component is typically resin, with the addition of carbon black or other fade-resistant dyes to give the markings the required color and stability.

[0028] However, during aircraft service, the outer surface markings are exposed to complex natural environments (such as ultraviolet radiation, temperature changes, humidity, rain, snow, and sandstorms) and specific flight environments (such as high-speed airflow, air pressure changes, and contamination from fuel and hydraulic fluid). This easily leads to wear, fading, blurring, and even detachment of the markings and printed information, severely affecting their identification function and lifespan. To effectively protect the markings and their printed content, a protective varnish is usually applied to the outer surface after the markings are pasted, forming a protective film to isolate them from external environmental factors. Currently, commercially available varnishes for protecting aircraft outer surface markings, such as C01-7 alkyd varnish, while providing basic protection to some extent, have gradually revealed many defects in practical applications. First, these alkyd varnishes have compatibility issues with the resin-based carbon ribbons used for printing the markings. The solvents or film-forming substances in the varnish can easily dissolve or swell the resin-based markings printed on the carbon ribbon, causing the marking lines to become blurred, deformed, or even disappear, severely damaging the integrity and readability of the markings. Secondly, existing clear varnishes have poor edge sealing properties, making it difficult to form a dense and robust protective layer on the edges of the label. Moisture, dust, and other harmful substances can easily penetrate from the edges, causing the label to peel and flake, thus shortening its overall lifespan. Furthermore, existing clear varnishes perform poorly in terms of high-temperature resistance. Aircraft may experience high temperatures while parked on the ground or in flight (e.g., summer sun exposure or aerodynamic heating during high-speed flight). After high-temperature testing, these clear varnishes are prone to yellowing, affecting not only the aircraft's appearance but also potentially reducing the varnish's transparency and protective performance, and even negatively impacting the visibility of the label markings. In addition, with increasing demands for aircraft maintenance efficiency, higher requirements are placed on the curing performance of protective clear varnishes, such as the ability to cure rapidly at room temperature to shorten aircraft downtime and improve operational efficiency.

[0029] Based on this, this application provides a protective varnish for aircraft outer surface marking tape, which can solve the problems of existing protective varnishes for aircraft outer surface marking tape, such as poor compatibility with the printed content of the marking tape (easy to dissolve), poor edge sealing effect, insufficient high temperature resistance (easy to yellow), and slow curing speed at room temperature.

[0030] Specifically, in the first aspect, this application provides a protective clear coat for marking tape on the outer surface of an aircraft, comprising a base material and a curing agent system; wherein, by weight, the base material comprises the following components: 60 to 70 parts of low molecular weight silicone-modified epoxy resin, 1 to 10 parts of glass powder, 0.5 to 3 parts of defoamer, 0.5 to 3 parts of leveling agent, and 10 to 30 parts of mixed solvent; and by weight, the curing agent system comprises the following components: 1 to 5 parts of catalyst and 1 to 5 parts of amine curing agent.

[0031] In this application, the base material is based on low molecular weight silicone-modified epoxy resin. The silicone component possesses excellent high-temperature stability, while the modified epoxy resin enhances the density and adhesion of the paint film. The combination of the two achieves a non-yellowing and transparent effect at 150℃ for 100 hours, perfectly suited to the high-temperature service environment of aircraft exterior surfaces. Simultaneously, glass powder is added to further enhance the high-temperature resistance and mechanical strength of the paint film, preventing cracking and peeling at high temperatures. Precise control of the amount of defoamer and leveling agent in the base material balances the leveling properties and shrinkage rate of the paint film, ensuring a continuous and dense sealing layer at the edges of the label. At the same time, the amine curing agent is a multifunctional type, capable of bidirectional reaction with epoxy and silicone resins, and its good flexibility further inhibits post-curing shrinkage, strengthening the edge sealing effect. The curing agent system uses a synergistic combination of catalyst and amine curing agent, achieving room temperature curing at 25℃ for 4 hours without high-temperature baking, significantly shortening aircraft downtime for maintenance and improving operational efficiency.

[0032] As some optional embodiments of this application, the molecular weight of the modified low molecular weight silicone-modified epoxy resin after modification is below 3000. The silicone monomer of the modified low molecular weight silicone-modified epoxy resin includes at least one of phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane. This application uses a high-performance film-forming resin, whose silicone resin has extremely high bond energy and thermal stability, and can play an excellent role in high temperature resistance and anti-yellowing. After being combined with epoxy resin, it retains the heat resistance of silicone while taking into account the excellent adhesion and mechanical strength of epoxy resin.

[0033] As some optional embodiments of this application, the low molecular weight organosilicon-modified epoxy resin is prepared by the following method: organosilicon monomers, water, and acetic acid are mixed and subjected to a pre-hydrolysis reaction; low molecular weight epoxy resin is added and subjected to a heated reaction; the mixture is then separated and purified to obtain the final product. Preferably, the pre-hydrolysis reaction temperature is 45℃~55℃, and the reaction time is 100min~150min. The heated reaction temperature is 75℃~85℃, and the reaction time is 4.5h~5.5h.

[0034] Preferably, the mass ratio of organosilicon monomer, water, acetic acid, and low molecular weight epoxy resin is 5~15:5:2:100. The low molecular weight epoxy resin is preferably at least one of E-42 epoxy resin, E-44 epoxy resin, and E-51 epoxy resin, which can be purchased from any commercially available company, such as Phoenix brand WSR6101, Baling Petrochemical epoxy resin, Nantong Changchen Chemical epoxy resin, etc.

[0035] As some optional embodiments of this application, the mixed solvent includes propylene glycol methyl ether acetate, xylene, and n-butyl acetate in a mass ratio of 40~50:30~40:10~30. In this application, the base material and the curing agent use the same solvent system; that is, the protective varnish is prepared and used immediately during preparation. Therefore, the mixed solvent for dissolving the base material is also the mixed solvent for dissolving the curing agent. This fundamentally solves the problem of traditional varnishes dissolving the printed content of resin-based carbon ribbons, ensuring the clarity and integrity of the markings. Specifically, the solvent system of this application has good solubility for the film-forming resin of the varnish itself (such as silicone epoxy resin), ensuring the application performance of the protective varnish. Furthermore, the solubility for specific resin-based carbon ribbons is significantly reduced, achieving an insoluble effect, thereby protecting the printed content.

[0036] As some optional embodiments of this application, the defoamer includes at least one of BYK-066N, BYK-077, and BYK-085.

[0037] As some optional embodiments of this application, the leveling agent includes at least one of BYK-306, BYK-310, and BYK-330.

[0038] As some optional embodiments of this application, the particle size of the glass powder is 600 mesh, 800 mesh, 1250 mesh, 3000 mesh or 5000 mesh. Preferably, the glass powder is a low melting point glass powder, that is, its initial melting temperature is around 200°C. While reinforcing the mechanical properties of the protective varnish, it can also give the protective varnish short-term high temperature resistance, such as being able to maintain at 200°C to 250°C for 30 minutes.

[0039] As some optional embodiments of this application, the catalyst is a platinum complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane or a platinum complex of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane. The amine curing agent includes at least one of ethylenediamine, diethylenetriamine, triethylenetetraamine, and hexamethylenediamine. This application employs a dual-curing system, adding a platinum metal catalyst to efficiently catalyze the addition reaction of the silicone resin, thereby significantly reducing the curing temperature and reaction time of this part; the addition of a highly reactive multifunctional amine curing agent ensures that the epoxy resin can also rapidly crosslink and cure at room temperature. The two curing reactions proceed simultaneously or sequentially at room temperature, working together to achieve rapid curing of the entire protective varnish system at room temperature, greatly shortening the aircraft maintenance cycle and improving operational efficiency.

[0040] Secondly, based on a general inventive concept, this application also provides a method for preparing a protective varnish for marking tapes on the outer surface of aircraft, comprising the following steps: S1. The low molecular weight organosilicon modified epoxy resin is mixed with a mixed solvent and then dispersed uniformly at a first rotation speed. The glass powder is added and dispersion is continued to obtain a premixed liquid.

[0041] S2. Add the defoamer and leveling agent to the premixed liquid and disperse them evenly at the second rotation speed to obtain a dispersion.

[0042] S3. The dispersion is ball-milled at a third rotation speed and sieved to obtain the base material.

[0043] S4. The catalyst and amine curing agent are mixed and dispersed evenly at the first rotation speed to obtain the curing agent; S5. Before use, mix the base material and the curing agent to prepare the protective varnish for the aircraft outer surface marking tape.

[0044] In a specific embodiment, the first rotation speed is 800 r / min to 1000 r / min, the second rotation speed is 500 r / min to 800 r / min, the third rotation speed is 300 r / min to 350 r / min, the dispersion time after each addition of a new component is 10 min to 30 min, the ball milling time is 2 h to 3 h, and the sieve size is 30 μm.

[0045] In summary, this application has at least the following advantages: (1) Printed content of undissolved label tape The printed content on the label tape is printed using a resin-based carbon ribbon. The appearance of uneven printing on the label tape is due to the solvent in the varnish dissolving the resin-based carbon ribbon. Both the varnish and the resin-based carbon ribbon are primarily composed of polymer materials. The solvent's ability to dissolve polymer materials mainly follows the principle of "like dissolves like." Common solvents used in protective varnishes are mainly aromatic hydrocarbons (such as benzene, toluene, xylene, etc.), while resin-based carbon ribbons often contain phenyl groups to improve their temperature resistance. According to the principle of "like dissolves like," aromatic hydrocarbon solvents and carbon ribbons have good solubility. This application screened a suitable mixed solvent system (40-50 parts propylene glycol methyl ether acetate, 30-40 parts xylene, and 30-10 parts n-butyl acetate) through mixing solvent experiments. Under this mixed solvent ratio, the resin-based carbon ribbon used will not dissolve, and the solvent can dissolve and disperse the components of the varnish.

[0046] (2) High temperature resistance The protective varnish of this application has excellent high-temperature resistance properties, which can meet the requirements of not yellowing at 150℃ for 100 hours and still maintaining transparency.

[0047] (3) Good edge sealing effect The protective varnish of this application achieves good edge sealing for label tapes by adjusting the composition of additives and the curing agent system, thereby regulating the surface tension and shrinkage rate of the protective varnish during curing. The additives used include defoamers and leveling agents. When the amount of additives added is lower than the ratio specified in this application, the protective varnish suffers from poor defoaming and leveling properties; when the amount of additives added is higher than the ratio specified in this application, it leads to excessively low surface tension and excessive shrinkage rate after curing, posing a risk of label edge flash. Simultaneously, the curing agent used in this application is a multifunctional amine curing agent. This type of curing agent can undergo ring-opening polymerization with the epoxy groups on epoxy resin and condensation reaction with the silanol groups on silicone resin, while also exhibiting high flexibility, avoiding the potential problem of excessive shrinkage rate after curing of the protective varnish.

[0048] (4) It can be cured quickly at room temperature. The curing agent in this application uses a catalyst and an amine curing agent, enabling rapid room temperature curing of the protective varnish (i.e., curing in 4 hours at 25°C). The catalyst used is a platinum metal catalyst, which utilizes the coordination activation characteristics of platinum with silicon-hydrogen bonds (Si-H) and silyl vinyl groups (Si-CH=CH2) to significantly reduce the curing temperature of the organosilicon resin portion, thus achieving low-temperature curing of the protective varnish. The curing agent used is a multifunctional and highly reactive amine-based curing agent, endowing the protective varnish with rapid curing capabilities. Through the synergistic effect of these two components, rapid room temperature curing of the protective varnish is achieved.

[0049] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0050] The low molecular weight organosilicon-modified epoxy resins in the embodiments of this application were all prepared by the following methods: (1) Mix 10 parts of organosilicon monomers (3 parts of phenyltrimethoxysilane, 3 parts of phenyltriethoxysilane, 4 parts of dimethyldiethoxysilane), 5 parts of deionized water and 2 parts of acetic acid, and perform a pre-hydrolysis reaction at 50°C for 2 hours.

[0051] (2) Add 100 parts of low molecular weight epoxy resin E-44 (molecular weight 1000-2000) and heat to 80℃ for 5 hours.

[0052] (3) The byproduct methanol was removed by vacuum distillation at a vacuum degree of 0.1 Pa and a temperature of 60 °C to obtain the modified low molecular weight organosilicon modified epoxy resin.

[0053] Example 1 This embodiment provides a protective varnish for marking tapes on the outer surface of aircraft, which is prepared by the following method: (1) Add 60 parts of low molecular weight organosilicon modified epoxy resin and 10 parts of mixed solvent to a dispersion tank and disperse at 800 r / min for 20 min until uniform to obtain the first dispersion. The mixed solvent includes 40 parts of propylene glycol methyl ether acetate, 30 parts of xylene and 30 parts of n-butyl acetate.

[0054] (2) Add 4 portions of 3000-mesh glass powder to the first dispersion and disperse at 800 r / min for 30 min until it is uniform to obtain the second dispersion.

[0055] (3) Add 0.5 parts of BYK-066N defoamer and 0.5 parts of BYK-306 leveling agent to the second dispersion, disperse at a speed of 600 r / min for 20 min, disperse until uniform, and obtain the third dispersion.

[0056] (4) Transfer the third dispersion to a ball mill jar and ball mill at 300 r / min for 2 h. After ball milling, sieve through a 30 μm sieve to obtain the base material.

[0057] (5) Add 1 part of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 0.5 part of ethylenediamine and 0.5 part of diethylenetriamine to a dispersion tank, disperse at a speed of 800 r / min for 10 min, and obtain the curing agent after dispersion to a uniform state.

[0058] (6) Before use, mix the obtained base material and hardener to prepare a protective varnish on the spot. The used label tape is as follows: Figure 1 As shown, the handwriting is clearly visible.

[0059] Example 2 This embodiment provides a protective varnish for marking tapes on the outer surface of aircraft, which is prepared by the following method: (1) Add 65 parts of low molecular weight organosilicon modified epoxy resin and 20 parts of mixed solvent to a dispersion tank and disperse at 800 r / min for 30 min until uniform dispersion is obtained to obtain the first dispersion. The mixed solvent includes 50 parts of propylene glycol methyl ether acetate, 40 parts of xylene and 10 parts of n-butyl acetate.

[0060] (2) Add 3 portions of 5000 mesh glass powder to the first dispersion and disperse at a speed of 800 r / min for 30 min until it is uniform to obtain the second dispersion.

[0061] (3) Add 1 part of BYK-066N defoamer and 2 parts of BYK-306 leveling agent to the second dispersion, disperse at a speed of 600 r / min for 20 min, disperse until uniform, and obtain the third dispersion.

[0062] (4) Transfer the third dispersion to a ball mill jar and ball mill at 300 r / min for 2 h. After ball milling, sieve through a 30 μm sieve to obtain the base material.

[0063] (5) Add 1 part of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex, 1 part of ethylenediamine and 1 part of diethylenetriamine to a dispersion tank, disperse at a speed of 800 r / min for 10 min, and obtain the curing agent after dispersion to a uniform state.

[0064] (6) Before use, mix the obtained base material and curing agent and prepare it for immediate use.

[0065] Example 3 This embodiment provides a protective varnish for marking tapes on the outer surface of aircraft, which is prepared by the following method: (1) Add 70 parts of low molecular weight organosilicon modified epoxy resin and 15 parts of mixed solvent to a dispersion tank and disperse at a speed of 800 r / min for 20 min until uniform dispersion is obtained to obtain the first dispersion. Among them, mixed solvent A includes 50 parts of propylene glycol methyl ether acetate, 40 parts of xylene and 10 parts of n-butyl acetate.

[0066] (2) Add 3 portions of 5000 mesh glass powder to the first dispersion and disperse at a speed of 800 r / min for 30 min until it is uniform to obtain the second dispersion.

[0067] (3) Add 3 parts of BYK-066N defoamer and 3 parts of BYK-306 leveling agent to the second dispersion, disperse at a speed of 600 r / min for 20 min, disperse until uniform, and obtain the third dispersion.

[0068] (4) Transfer the third dispersion to a ball mill jar and ball mill at 300 r / min for 2 h. After ball milling, sieve through a 30 μm sieve to obtain the base material.

[0069] (5) Add 1 part of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane platinum complex, 1 part of hexamethylenediamine, 0.5 part of triethylenetetramine and 1 part of isophoronediamine to a dispersion tank and disperse at a speed of 800 r / min for 10 min. After dispersion to a uniform state, the curing agent is obtained.

[0070] (6) Before use, mix the obtained base material and curing agent and prepare it for immediate use.

[0071] Comparative Example 1 The difference between this comparative example and Example 1 is that pure xylene is used as the solvent for both the base material and the curing agent. When using the protective varnish prepared in Comparative Example 1, it will dissolve the contents of the label tape, such as... Figure 2 As shown.

[0072] Comparative Example 2 The difference between this comparative example and Example 1 is that the base material uses unmodified low molecular weight epoxy resin E-44 instead of low molecular weight silicone-modified epoxy resin. When using the protective varnish prepared in Comparative Example 2, it turns yellow and brittle after being heated to 150°C for 3 hours. Figure 3 As shown.

[0073] Comparative Example 3 The difference between this comparative example and Example 1 is that the leveling agent in this example is 0.5 parts, and only ethylenediamine is added to the curing agent. When using the protective varnish prepared in Comparative Example 3, the varnish is prone to peeling after curing. Figure 4 As shown.

[0074] Comparative Example 4 The difference between this comparative example and Example 1 is that the curing agent does not contain 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex. During the preparation process, the protective varnish is difficult to cure at room temperature, and the surface is still soft one day after application.

[0075] As can be seen from Comparative Example 1, existing varnishes (such as CO1-7 alkyd varnish) commonly use aromatic solvents (such as pure xylene), while resin-based carbon tapes contain phenyl groups to improve temperature resistance. Due to the principle of like dissolves like, they easily dissolve, which can cause the printed content of the label tape to become smudged (e.g., ...). Figure 2 This application, through the formulation of mixed solvents, can not only meet the dissolution and dispersion requirements of the varnish base material, but also, due to the introduction of non-aromatic solvents (propylene glycol methyl ether acetate, n-butyl acetate), break the similar structure of aromatic solvents and carbon ribbon phenyl groups, thus avoiding the dissolution of resin-based carbon ribbons and ensuring that the printed content of the label tape is clear and free of blurring.

[0076] As can be seen from Comparative Example 2, the varnish of this application uses organosilicon epoxy resin as the key component. The organosilicon resin itself has excellent high-temperature stability (high silicon-oxygen bond energy, strong resistance to oxidation and decomposition), while the epoxy resin improves the density and adhesion of the paint film. The composite resin structure formed by the combination of the two can maintain chemical stability for a long time in a high-temperature environment of 150℃, avoiding yellowing, loss of gloss or cracking of the paint film, and meeting the usage requirements of aircraft external surface temperature fluctuations (especially high-temperature areas near the engine).

[0077] As can be seen from Comparative Example 3, this application strictly controls the amount of additives added to 1%~7% (additives include defoamers and leveling agents, the amount of which accounts for 1%~7% of the mass of the protective clear varnish for the aircraft outer surface marking tape). When it is below 1%, the paint film is prone to bubbles and poor leveling, making it impossible to form a continuous sealing layer; when it is above 7%, it will result in too low surface tension of the paint film, too large shrinkage rate after curing, and easy appearance of marking tape burrs. By precisely controlling the amount, good leveling properties and no bubbles in the paint film are ensured, laying the foundation for sealing the edge of the marking tape.

[0078] As shown in Comparative Example 4, platinum in the platinum metal catalyst can coordinate and activate the silicon-hydrogen bonds (Si-H) and silanyl vinyl groups (Si-CH=CH2) in the silicone resin, significantly reducing the curing temperature of the silicone resin and enabling it to cure at room temperature, breaking the limitation of traditional silicone resins requiring high-temperature curing. The multifunctional, highly reactive amine curing agent exhibits high reactivity and can rapidly react simultaneously with the epoxy groups of epoxy resin (ring-opening polymerization) and the silanol groups of silicone resin (condensation reaction), forming a paint film with high cross-linking density. Furthermore, its good flexibility can offset the shrinkage stress during the curing process, preventing the label tape edge sealing failure due to excessive shrinkage, ultimately achieving good edge sealing of the label tape. Simultaneously, in synergy with the platinum metal catalyst, it accelerates the room-temperature curing of both the silicone resin and epoxy resin components in the varnish, ultimately achieving a rapid curing effect of 4 hours at 25°C, significantly shortening aircraft maintenance downtime.

[0079] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0080] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0081] Finally, it should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0082] This application uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A protective varnish for marking tapes on the outer surface of aircraft, characterized in that, The system includes a base material and a curing agent, wherein the base material comprises the following components in parts by weight: 60 to 70 parts of low molecular weight silicone-modified epoxy resin, 1 to 10 parts of glass powder, 0.5 to 3 parts of defoamer, 0.5 to 3 parts of leveling agent, and 10 to 30 parts of mixed solvent.

2. The protective varnish for aircraft outer surface marking tape according to claim 1, characterized in that, The low molecular weight organosilicon-modified epoxy resin has a molecular weight of less than 3000, and the organosilicon monomer of the low molecular weight organosilicon-modified epoxy resin includes at least one of phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane.

3. The protective varnish for marking tapes on the outer surface of aircraft according to claim 1, characterized in that, The low molecular weight organosilicon-modified epoxy resin is prepared by the following method: The organosilicon monomer, water, and acetic acid are mixed and then subjected to a pre-hydrolysis reaction. The product is prepared by adding low molecular weight epoxy resin, heating and reacting, and then separating and purifying it.

4. The protective varnish for aircraft outer surface marking tape according to claim 3, characterized in that, The mass ratio of the organosilicon monomer, water, acetic acid, and low molecular weight epoxy resin is 5~15:5:2:

100.

5. The protective varnish for aircraft outer surface marking tape according to claim 3, characterized in that, The pre-hydrolysis reaction is carried out at a temperature of 45℃~55℃ for a time of 100min~150min.

6. The protective varnish for marking tapes on the outer surface of aircraft according to claim 3, characterized in that, The reaction temperature of the heating reaction is 75℃~85℃, and the reaction time is 4.5h~5.5h.

7. The protective varnish for marking tapes on the outer surface of aircraft according to claim 1, characterized in that, The mixed solvent comprises propylene glycol methyl ether acetate, xylene, and n-butyl acetate in a mass ratio of 40~50:30~40:10~30.

8. The protective varnish for marking tapes on the outer surface of aircraft according to claim 1, characterized in that, The defoamer includes at least one of BYK-066N, BYK-077, and BYK-085.

9. The protective varnish for marking tapes on the outer surface of aircraft according to claim 1, characterized in that, The leveling agent includes at least one of BYK-306, BYK-310, and BYK-330.

10. The protective varnish for marking tapes on the outer surface of an aircraft according to claim 1, characterized in that, The glass powder has a particle size of 600 mesh, 800 mesh, 1250 mesh, 3000 mesh, or 5000 mesh.

11. The protective varnish for marking tapes on the outer surface of an aircraft according to claim 1, characterized in that, The curing agent system comprises the following components by weight: 1 to 5 parts of catalyst and 1 to 5 parts of amine curing agent.

12. The protective varnish for marking tapes on the outer surface of an aircraft according to claim 11, characterized in that, The catalyst is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex or a 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane platinum complex.

13. The protective varnish for marking tapes on the outer surface of an aircraft according to claim 11, characterized in that, The amine curing agent includes at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, and hexamethylenediamine.

14. A method for preparing a protective varnish for marking tapes on the outer surface of an aircraft according to any one of claims 1-13, characterized in that, Includes the following steps: The low molecular weight organosilicon modified epoxy resin is mixed with a mixed solvent and then dispersed uniformly at a first rotation speed. The glass powder is added and dispersion is continued to obtain a premixed liquid. The defoamer and leveling agent are added to the premixed liquid and dispersed uniformly at the second rotation speed to obtain a dispersion. The dispersion was ball-milled at a third rotation speed and then sieved to obtain the base material; The catalyst is mixed with an amine curing agent and then dispersed evenly at the first rotation speed to obtain the curing agent. Before use, the base material and the curing agent are mixed to prepare the protective varnish for the aircraft outer surface marking tape.

15. The preparation method according to claim 14, characterized in that, The first rotational speed is 800 r / min to 1000 r / min, the second rotational speed is 500 r / min to 800 r / min, and the third rotational speed is 300 r / min to 350 r / min. The dispersion time for each dispersion is 10 min to 30 min.

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